(vii)

PREFACE

Fourth edition of the book has been thoroughly revised, updated, and published in an attractive

colour format. This endeavour has enhanced the lucidity of the figures and overall aesthetics of the

book.

The fast-developing advances in the field of medical sciences and technology has beset the present-

day medical students with voluminous university curriculae. Keeping in view the need of the students

for a ready-made material for their practical examinations and various postgraduate entrance tests,

the book has been expanded into two sections and is accompanied with ‘Review of Ophthalmology’

as a pocket companion, and converted into a comprehensive book.

Section 1: Anatomy, Physiology and Diseases of the Eye. This part of the book includes 20

chapters, 1 each on Anatomy and Physiology of Eye and rest 18 on diseases of the different structures

of the eye.

Section II: Practical Ophthalmology. This section includes chapter on ‘Clinical Methods in

Ophthalmology’ and different other aspects essential to the practical examinations viz. Clinical

Ophthalmic Cases, Darkroom Procedures, and Ophthalmic Instruments.

Review of Ophthalmology: Quick Text Review and Multiple-Choice Questions. This pocket

companion provides an indepth revision of the subject at a glance and an opportunity of self-assessment,

and thus makes it the book of choice for preparing for the various postgraduate entrance examinations.

Salient Features of the Book

Each chapter begins with a brief overview highlighting the topics covered followed by relevant

applied anatomy and physiology. The text is then organized in such a way that the students

can easily understand, retain and reproduce it. Various levels of headings, subheadings, bold

face and italics given in the text will be helpful in a quick revision of the subject.

Text is complete and up-to-date with recent advances such as refractive surgery, manual small

incision cataract surgery (SICS), phacoemulsification, newer diagnostic techniques as well as

newer therapeutics.

To be true, some part of the text is in more detail than the requirement of undergraduate

students. But this very feature of the book makes it a useful handbook for the postgraduate

students.

The text is illustrated with plenty of diagrams. The illustrations mostly include clinical

photographs and clear-line diagrams providing vivid and lucid details.

Operative steps of the important surgical techniques have been given in the relevant chapters.

Wherever possible important information has been given in the form of tables and flowcharts.

An attraction of this edition of the book is a very useful addition of the

‘Practical

Ophthalmology’ section to help the students to prepare for the practical examinations.

(viii)

It would have not been possible for this book to be in its present form without the generous help

of many well wishers and stalwarts in their fields. Surely, I owe sincere thanks to them all. Those

who need special mention are Prof. Inderbir Singh, Ex-HOD, Anatomy, PGIMS, Rohtak, Prof.

R.C. Nagpal, HIMS, Dehradun, Prof. S. Soodan from Jammu, Prof. B. Ghosh, Chief GNEC, New

Delhi, Prof. P.S. Sandhu, GGS Medical College, Faridkot, Prof. S.S. Shergil, GMC, Amritsar, Prof.

R.K. Grewal and Prof. G.S. Bajwa, DMC Ludhiana, Prof. R.N. Bhatnagar, GMC, Patiala, Prof.

V.P. Gupta, UCMS, New Delhi, Prof. K.P. Chaudhary, GMC, Shimla, Prof. S. Sood, GMC,

Chandigarh, Prof. S. Ghosh, Prof. R.V. Azad and Prof. R.B. Vajpayee from Dr. R.P. Centre for

Opthalmic Sciences, New Delhi, and Prof. Anil Chauhan, GMC, Tanda.

I am deeply indebted to Prof. S.P. Garg. Prof. Atul Kumar, Prof. J.S. Tityal, Dr. Mahipal S.

Sachdev, Dr. Ashish Bansal, Dr. T.P. Dass, Dr. A.K. Mandal, Dr. B. Rajeev and Dr. Neeraj

Sanduja for providing the colour photographs.

I am grateful to Prof. C.S. Dhull, Chief and all other faculty members of Regional Institute of

Opthalmology (RIO), PGIMS, Rohtak namely Prof. S.V. Singh, Dr. J.P. Chugh, Dr. R.S. Chauhan,

Dr. Manisha Rathi, Dr. Neebha Anand, Dr. Manisha Nada, Dr. Ashok Rathi, Dr. Urmil Chawla

and Dr. Sumit Sachdeva for their kind co-operation and suggestions rendered by them from time

to time. The help received from all the resident doctors including Dr. Shikha, Dr. Vivek Sharma

and Dr. Nidhi Gupta is duly acknowledged. Dr. Saurabh and Dr. Ashima deserve special thanks

for their artistic touch which I feel has considerably enhanced the presentation of the book. My

sincere thanks are also due to Prof. S.S. Sangwan, Director, PGIMS, Rohtak for providing a working

atmosphere. Of incalculable assistance to me has been my wife Dr. Indu Khurana, Assoc. Prof.

in Physiology, PGIMS, Rohtak. The enthusiastic co-operation received from Mr. Saumya Gupta,

and Mr. R.K. Gupta, Managing Directors, New Age International Publishers (P) Ltd., New Delhi

needs special acknowledgement.

Sincere efforts have been made to verify the correctness of the text. However, in spite of best

efforts, ventures of this kind are not likely to be free from human errors, some inaccuracies,

ambiguities and typographic mistakes. Therefore, all the users are requested to send their feedback

and suggestions. The importance of such views in improving the future editions of the book cannot

be overemphasized. Feedbacks received shall be highly appreciated and duly acknowledged.

Rohtak

A K Khurana

(ix)

C O NCOT

NTS

Preface

vii

SECTION I: ANATOMY, PHYSIOLOGY AND DISEASES OF THE EYE

Anatomy and Development of the Eye

Physiology of Eye and Vision

Optics and Refraction

Diseases of the Conjunctiva

Diseases of the Cornea

Diseases of the Sclera

127

Diseases of the Uveal Tract

133

Diseases of the Lens

167

Glaucoma

205

10.

Diseases of the Vitreous

243

11.

Diseases of the Retina

249

12.

Neuro-ophthalmology

287

13.

Strabismus and Nystagmus

313

14.

Diseases of the Eyelids

339

15.

Diseases of the Lacrimal Apparatus

363

16.

Diseases of the Orbit

377

17.

Ocular Injuries

401

18.

Ocular Therapeutics, Lasers and Cryotherapy in Ophthalmology

417

19.

Systemic Ophthalmology

433

20.

Community Ophthalmology

443

SECTION II: PRACTICAL OPHTHALMOLOGY

21. Clinical Methods in Ophthalmology

461

22. Clinical Ophthalmic Cases

499

23. Darkroom Procedures

543

24. Ophthalmic Instruments and Operative Ophthalmology

571

Index

593

Anatomy and

CHAPTER

of the Eye

1Development

ANATOMY OF THE EYE

z Formation of lens vesicle

z The eyeball

z Formation of optic cup

z Visual pathway

z Changes in the associated mesoderm

z Orbit, extraocular muscles and

z Development of various ocular

structures

appendages of the eye

z Structures derived from the embryonic

DEVELOPMENT OF THE EYE

layers

z Formation of optic vesicle and

z Important milestones in the development

optic stalk

of the eye

Coats of the eyeball

ANATOMY OF THE EYE

The eyeball comprises three coats: outer (fibrous

coat), middle (vascular coat) and inner (nervous coat).

This chapter gives only a brief account of the anatomy

of eyeball and its related structures. The detailed

1. Fibrous coat. It is a dense strong wall which

anatomy of different structures is described in the

protects the intraocular contents. Anterior 1/6th of

relevant chapters.

this fibrous coat is transparent and is called cornea.

Posterior 5/6th opaque part is called sclera. Cornea is

THE EYEBALL

set into sclera like a watch glass. Junction of the

Each eyeball (Fig. 1.1) is a cystic structure kept

cornea and sclera is called limbus. Conjunctiva is

distended by the pressure inside it. Although,

firmly attached at the limbus.

generally referred to as a globe, the eyeball is not a

2. Vascular coat (uveal tissue). It supplies nutrition

sphere but an ablate spheroid. The central point on

to the various structures of the eyeball. It consists of

the maximal convexities of the anterior and posterior

three parts which from anterior to posterior are : iris,

curvatures of the eyeball is called the anterior and

ciliary body and choroid.

posterior pole, respectively. The equator of the

3. Nervous coat (retina). It is concerned with visual

eyeball lies at the mid plane between the two poles

functions.

(Fig.1.2).

Segments and chambers of the eyeball

Dimensions of an adult eyeball

The eyeball can be divided into two segments:

Anteroposterior diameter

24 mm

anterior and posterior.

Horizontal diameter

23.5 mm

1. Anterior segment. It includes crystalline lens

Vertical diameter

23 mm

(which is suspended from the ciliary body by zonules),

Circumference

75 mm

and structures anterior to it, viz., iris, cornea and two

Volume

6.5 ml

aqueous humour-filled spaces : anterior and posterior

Weight

7 gm

chambers.

Comprehensive OPHTHALMOLOGY

Fig. 1.1. Gross anatomy of the eyeball.

z Anterior chamber. It is bounded anteriorly by

z Posterior chamber. It is a triangular space

the back of cornea, and posteriorly by the iris

containing

0.06 ml of aqueous humour. It is

and part of ciliary body. The anterior chamber is

bounded anteriorly by the posterior surface of

about 2.5 mm deep in the centre in normal adults.

iris and part of ciliary body, posteriorly by the

It is shallower in hypermetropes and deeper in

crystalline lens and its zonules, and laterally by

myopes, but is almost equal in the two eyes of

the ciliary body.

the same individual. It contains about 0.25 ml of

2. Posterior segment. It includes the structures

the aqueous humour.

posterior to lens, viz., vitreous humour (a gel like

material which fills the space behind the lens), retina,

choroid and optic disc.

VISUAL PATHWAY

Each eyeball acts as a camera; it perceives the images

and relays the sensations to the brain (occipital

cortex) via visual pathway which comprises optic

nerves, optic chiasma, optic tracts, geniculate bodies

and optic radiations (Fig. 1.3).

ORBIT, EXTRAOCULAR MUSCLES AND

APPENDAGES OF THE EYE (FIG. 1.4)

Each eyeball is suspended by extraocular muscles

Fig. 1.2. Poles and equators of the eyeball.

and fascial sheaths in a quadrilateral pyramid-shaped

ANATOMY AND DEVELOPMENT OF THE EYE

bony cavity called orbit (Fig. 1.4). Each eyeball is

z Visceral mesoderm of maxillary process.

located in the anterior orbit, nearer to the roof and

Before going into the development of individual

lateral wall than to the floor and medial wall. Each eye

structures, it will be helpful to understand the

is protected anteriorly by two shutters called the

formation of optic vesicle, lens placode, optic cup

eyelids. The anterior part of the sclera and posterior

and changes in the surrounding mesenchyme, which

surface of lids are lined by a thin membrane called

play a major role in the development of the eye and

conjunctiva. For smooth functioning, the cornea and

its related structures.

conjunctiva are to be kept moist by tears which are

produced by lacrimal gland and drained by the lacrimal

passages. These structures (eyelids, eyebrows,

conjunctiva and lacrimal apparatus) are collectively

called ‘the appendages of the eye’.

DEVELOPMENT OF THE EYE

The development of eyeball can be considered to

commence around day 22 when the embryo has eight

pairs of somites and is around 2 mm in length. The

eyeball and its related structures are derived from the

following primordia:

z Optic vesicle,an outgrowth from prosencephalon

(a neuroectodermal structure),

z Lens placode, a specialised area of surface

ectoderm, and the surrounding surface ectoderm,

Fig. 1.3. Gross anatomy of the visual pathway.

z Mesenchyme surrounding the optic vesicle, and

Fig. 1.4. Section of the orbital cavity to demonstrate eyeball and its accessory structures.

Comprehensive OPHTHALMOLOGY

FORMATION OF OPTIC VESICLE

AND OPTIC STALK

The area of neural plate (Fig. 1.5A) which forms the

prosencepholon develops a linear thickened area on

either side (Fig. 1.5B), which soon becomes depressed

to form the optic sulcus (Fig. 1.5C). Meanwhile the

neural plate gets converted into prosencephalic

vesicle. As the optic sulcus deepens, the walls of the

prosencepholon overlying the sulcus bulge out to

form the optic vesicle (Figs. 1.5D, E&F). The proximal

part of the optic vesicle becomes constricted and

elongated to form the optic stalk (Figs. 1.5G&H).

FORMATION OF LENS VESICLE

The optic vesicle grows laterally and comes in contact

with the surface ectoderm. The surface ectoderm,

overlying the optic vesicle becomes thickened to form

the lens placode (Fig. 1.6A) which sinks below the

surface and is converted into the lens vesicle (Figs.

1.6 B&C). It is soon separated from the surface

ectoderm at 33rd day of gestation (Fig. 1.6D).

FORMATION OF OPTIC CUP

The optic vesicle is converted into a double-layered

optic cup. It appears from Fig. 1.6 that this has

happened because the developing lens has

invaginated itself into the optic vesicle. In fact

conversion of the optic vesicle to the optic cup is

due to differential growth of the walls of the vesicle.

The margins of optic cup grow over the upper and

lateral sides of the lens to enclose it. However, such a

growth does not take place over the inferior part of

the lens, and therefore, the walls of the cup show

deficiency in this part. This deficiency extends to

Fig. 1.5. Formation of the optic vesicle and optic stalk.

Fig. 1.6. Formation of lens vesicle and optic cup.

ANATOMY AND DEVELOPMENT OF THE EYE

some distance along the inferior surface of the optic

In the posterior part of optic cup the surrounding

stalk and is called the choroidal or fetal fissure

fibrous mesenchyme forms sclera and extraocular

(Fig. 1.7).

muscles, while the vascular layer forms the choroid

and ciliary body.

DEVELOPMENT OF VARIOUS

OCULAR STRUCTURES

Retina

Retina is developed from the two walls of the optic

cup, namely: (a) nervous retina from the inner wall,

and (b) pigment epithelium from the outer wall

(Fig. 1.10).

(a) Nervous retina. The inner wall of the optic cup is

a single-layered epithelium. It divides into several

layers of cells which differentiate into the following

three layers (as also occurs in neural tube):

Fig. 1.7. Optic cup and stalk seen from below to show

CHANGES IN THE ASSOCIATED MESENCHYME

The developing neural tube (from which central

nervous system develops) is surrounded by

mesenchyme, which subsequently condenses to form

meninges. An extension of this mesenchyme also

covers the optic vesicle. Later, this mesenchyme

differentiates to form a superficial fibrous layer

Fig. 1.8. Developing optic cup surrounded by mesenchyme.

(corresponding to dura) and a deeper vascular layer

(corresponding to pia-arachnoid) (Fig. 1.8).

With the formation of optic cup, part of the inner

vascular layer of mesenchyme is carried into the cup

through the choroidal fissure. With the closure of

this fissure, the portion of mesenchyme which has

made its way into the eye is cut off from the

surrounding mesenchyme and gives rise to the hyaloid

system of the vessels (Fig. 1.9).

The fibrous layer of mesenchyme surrounding the

anterior part of optic cup forms the cornea. The

corresponding vascular layer of mesenchyme

becomes the iridopupillary membrane, which in the

peripheral region attaches to the anterior part of the

optic cup to form the iris. The central part of this

lamina is pupillary membrane which also forms the

tunica vasculosa lentis (Fig. 1.9).

Fig. 1.9. Derivation of various structures of the eyeball.

Comprehensive OPHTHALMOLOGY

Crystalline lens

The crystalline lens is developed from the surface

ectoderm as below :

Lens placode and lens vesicle formation (see page

5, 6 and Fig. 1.6 .

Primary lens fibres. The cells of posterior wall of

lens vesicle elongate rapidly to form the primary lens

fibres which obliterate the cavity of lens vesicle. The

primary lens fibres are formed upto 3rd month of

gestation and are preserved as the compact core of

lens, known as embryonic nucleus (Fig. 1.11).

Fig. 1.10. Development of the retina.

Secondary lens fibres are formed from equatorial cells

of anterior epithelium which remain active through

z Matrix cell layer. Cells of this layer form the rods

out life. Since the secondary lens fibres are laid down

and cones.

concentrically, the lens on section has a laminated

z Mantle layer. Cells of this layer form the

appearance. Depending upon the period of

bipolar cells, ganglion cells, other neurons of

development, the secondary lens fibres are named as

retina and the supporting tissue.

below :

z Marginal layer. This layer forms the ganglion

z Fetal nucleus (3rd to 8th month),

cells, axons of which form the nerve fibre

z Infantile nucleus

(last weeks of fetal life to

layer.

puberty),

(b) Outer pigment epithelial layer. Cells of the outer

z Adult nucleus (after puberty), and

wall of the optic cup become pigmented. Its posterior

z Cortex (superficial lens fibres of adult lens)

part forms the pigmented epithelium of retina and the

Lens capsule is a true basement membrane produced

anterior part continues forward in ciliary body and

by the lens epithelium on its external aspect.

iris as their anterior pigmented epithelium.

Cornea (Fig. 1.9)

Optic nerve

1. Epithelium is formed from the surface ectoderm.

It develops in the framework of optic stalk as

2. Other layers viz. endothelium, Descemet's

membrane, stroma and Bowman's layer are derived

below:

from the fibrous layer of mesenchyme lying anterior

z Fibres from the nerve fibre layer of retina grow

to the optic cup (Fig. 1.9).

into optic stalk by passing through the choroidal

fissure and form the optic nerve fibres.

Sclera

The neuroectodermal cells forming the walls of

Sclera is developed from the fibrous layer of

optic stalk develop into glial system of the nerve.

mesenchyme surrounding the optic cup (corres-

z The fibrous septa of the optic nerve are

ponding to dura of CNS) (Fig. 1.9).

developed from the vascular layer of mesenchyme

Choroid

which invades the nerve at 3rd fetal month.

It is derived from the inner vascular layer of

Sheaths of optic nerve are formed from the layers

mesenchyme that surrounds the optic cup (Fig. 1.9).

of mesenchyme like meninges of other parts of

central nervous system.

Ciliary body

Myelination of nerve fibres takes place from

z The two layers of epithelium of ciliary body

brain distally and reaches the lamina cribrosa just

develop from the anterior part of the two layers

before birth and stops there. In some cases, this

of optic cup (neuroectodermal).

extends up to around the optic disc and presents

z Stroma of ciliary body, ciliary muscle and blood

as congenital opaque nerve fibres. These develop

vessels are developed from the vascular layer of

after birth.

mesenchyme surrounding the optic cup (Fig. 1.9).

ANATOMY AND DEVELOPMENT OF THE EYE

Vitreous

1. Primary or primitive vitreous is mesenchymal in

origin and is a vascular structure having the

hyaloid system of vessels.

2. Secondary or definitive or vitreous proper is

secreted by neuroectoderm of optic cup. This is

an avascular structure. When this vitreous fills

the cavity, primitive vitreous with hyaloid vessels

is pushed anteriorly and ultimately disappears.

3. Tertiary vitreous is developed from neuro-

ectoderm in the ciliary region and is represented

by the ciliary zonules.

Eyelids

Eyelids are formed by reduplication of surface

ectoderm above and below the cornea (Fig. 1.12). The

folds enlarge and their margins meet and fuse with

each other. The lids cut off a space called the

conjunctival sac. The folds thus formed contain some

mesoderm which would form the muscles of the lid

and the tarsal plate. The lids separate after the seventh

month of intra-uterine life.

Fig. 1.11. Development of the crystalline lens.

Iris

z Both layers of epithelium are derived from

the marginal region of optic cup

(neuro-

ectodermal) (Fig. 1.9).

z Sphincter and dilator pupillae muscles are

derived from the anterior epithelium

(neuro-

ectodermal).

z Stroma and blood vessels of the iris develop

from the vascular mesenchyme present anterior

Fig. 1.12. Development of the eyelids, conjunctiva and

to the optic cup.

lacrimal gland.

Comprehensive OPHTHALMOLOGY

Tarsal glands are formed by ingrowth of a regular

Neural ectoderm

row of solid columns of ectodermal cells from the lid

z Retina with its pigment epithelium

margins.

z Epithelial layers of ciliary body

Cilia develop as epithelial buds from lid margins.

z Epithelial layers of iris

z Sphincter and dilator pupillae muscles

Conjunctiva

z Optic nerve (neuroglia and nervous elements

Conjunctiva develops from the ectoderm lining the

only)

lids and covering the globe (Fig.1.12).

z Melanocytes

Conjunctival glands develop as growth of the basal

z Secondary vitreous

cells of upper conjunctival fornix. Fewer glands

z Ciliary zonules (tertiary vitreous)

develop from the lower fornix.

Associated paraxial mesenchyme

The lacrimal apparatus

z Blood vessels of choroid, iris, ciliary vessels,

Lacrimal gland is formed from about 8 cuneiform

central retinal artery, other vessels.

epithelial buds which grow by the end of 2nd month

z Primary vitreous

of fetal life from the superolateral side of the

z Substantia propria, Descemet's membrane and

conjunctival sac (Fig. 1.12).

endothelium of cornea

Lacrimal sac, nasolacrimal duct and canaliculi.

z The sclera

These structures develop from the ectoderm of

z Stroma of iris

nasolacrimal furrow. It extends from the medial angle

z Ciliary muscle

of eye to the region of developing mouth. The

z Sheaths of optic nerve

ectoderm gets buried to form a solid cord. The cord is

z Extraocular muscles

later canalised. The upper part forms the lacrimal sac.

z Fat, ligaments and other connective tissue

The nasolacrimal duct is derived from the lower part

structures of the orbit

as it forms a secondary connection with the nasal

z Upper and medial walls of the orbit

cavity. Some ectodermal buds arise from the medial

z Connective tissue of the upper eyelid

margins of eyelids. These buds later canalise to form

the canaliculi.

Visceral mesoderm of maxillary process

below the eye

Extraocular muscles

z Lower and lateral walls of orbit

All the extraocular muscles develop in a closely

z Connective tissue of the lower eyelid

associated manner by mesodermally derived

mesenchymal condensation. This probably

IMPORTANT MILESTONES IN THE

corresponds to preotic myotomes, hence the triple

DEVELOPMENT OF THE EYE

nerve supply (III, IV and VI cranial nerves).

Embryonic and fetal period

STRUCTURES DERIVED FROM

Stage of growth

Development

THE EMBRYONIC LAYERS

Based on the above description, the various

2.6 mm (3 weeks)

Optic pits appear on either

structures derived from the embryonic layers are given

side of cephalic end of

below :

forebrain.

3.5 mm (4 weeks)

Primary optic vesiclein-

1. Surface ectoderm

vaginates.

z The crystalline lens

5.5 to 6 mm

Development of embr-

z Epithelium of the cornea

yonic fissure

z Epithelium of the conjunctiva

10 mm (6 weeks)

Retinal layers differ-

z Lacrimal gland

entiate, lens vesicle formed.

z Epithelium of eyelids and its derivatives viz., cilia,

20 mm (9 weeks)

Sclera, cornea and extra-

tarsal glands and conjunctival glands.

ocular muscles differen-tiate.

z Epithelium lining the lacrimal apparatus.

ANATOMY AND DEVELOPMENT OF THE EYE

z Corneal diameter is about 10 mm. Adult size

25 mm (10 weeks) Lumen of optic nerve obliter-

(11.7 mm) is attained by 2 years of age.

ated.

z Anterior chamber is shallow and angle is narrow.

50 mm (3 months) Optic tracts completed, pars

z Lens is spherical at birth. Infantile nucleus is

ciliaris

retina grows

present.

forwards, pars iridica retina

z Retina. Apart from macular area the retina is fully

grows forward.

differentiated. Macula differentiates 4-6 months

60 mm (4 months) Hyaloid vessels atrophy, iris

after birth.

sphincter is formed.

z Myelination of optic nerve fibres has reached

230-265 mm

Fetal nucleus of lens is

the lamina cribrosa.

complete,

z Newborn is usually hypermetropic by +2 to +3 D.

(8th month)

all layers of retina nearly

z Orbit is more divergent (50°) as compared to

developed, macula starts

adult (45°).

differentiation.

z Lacrimal gland is still underdeveloped and tears

265-300mm

Except macula, retina is fully

are not secreted.

(9th month)

developed, infantile nucleus

Postnatal period

of lens begins to appear,

z Fixation starts developing in first month and is

pupillary membr-ane and

completed in 6 months.

hyaloid vessels disappear.

z Macula is fully developed by 4-6 months.

z Fusional reflexes, stereopsis and accommodation

Eye at birth

is well developed by 4-6 months.

Anteroposterior diameter of the eyeball is about z Cornea attains normal adult diameter by 2 years

16.5 mm (70% of adult size which is attained by

of age.

7-8 years).

z Lens grows throughout life.

Physiology of Eye

CHAPTER

and Vision

MAINTENANCE OF CLEAR

PHYSIOLOGY OF VISION

INTRODUCTION OCULAR MEDIA

Phototransduction

Physiology of tears

Processing and transmission of visual impulse

Visual perceptions

Physiology of cornea

PHYSIOLOGY OF OCULAR MOTILITY AND

Physiology of crystalline lens

BINOCULAR VISION

Physiology of aqueous humour and

Ocular motility

maintenance of intraocular pressure

Binocular single vision

Crystalline lens, and

INTRODUCTION

Vitreous humour

Sense of vision, the choicest gift from the Almighty

PHYSIOLOGY OF TEARS

to the humans and other animals, is a complex function

Tear film plays a vital role in maintaining the

of the two eyes and their central connections. The

physiological activities involved in the normal

transparency of cornea. The physiological apsects

functioning of the eyes are :

of the tears and tear film are described in the chapter

Maintenance of clear ocular media,

on diseases of the lacrimal apparatus (see page 364).

Maintenance of normal intraocular pressure,

PHYSIOLOGY OF CORNEA

The image forming mechanism,

Physiology of vision,

The cornea forms the main refractive medium of the

Physiology of binocular vision,

eye. Physiological aspects in relation to cornea

Physiology of pupil, and

include:

Physiology of ocular motility.

Transparency of cornea,

Nutrition and metabolism of cornea,

Permeability of cornea, and

MAINTENANCE OF CLEAR

Corneal wound healing.

OCULAR MEDIA

For details see page 90

The main prerequiste for visual function is the

PHYSIOLOGY OF CRYSTALLINE LENS

maintenance of clear refractive media of the eye. The

The crystalline lens is a transparent structure playing

major factor responsible for transparency of the ocular

main role in the focussing mechanism for vision. Its

media is their avascularity. The structures forming

physiological aspects include :

refractive media of the eye from anterior to posterior

Lens transparency

are :

Metabolic activities of the lens

Tear film,

Accommodation.

Cornea,

Aqueous humour,

For details see page 39 and 168

COMPREHENSIVE OPHTHALMOLOGY

PHYSIOLOGY OF AQUEOUS HUMOUR AND

stages (Fig. 2.1). The all trans-retinal so formed is

MAINTENANCE OF INTRAOCULAR PRESSURE

soon separated from the opsin. This process of

The aqueous humour is a clear watery fluid filling the

separation is called photodecomposition and the

anterior chamber (0.25ml) and the posterior chamber

rhodopsin is said to be bleached by the action of

(0.06ml) of the eyeball. In addition to its role in

light.

maintaining a proper intraocular pressure it also plays

Rhodopsin regeneration. The 11-cis-retinal is

an important metabolic role by providing substrates

regenerated from the all-trans-retinal separated from

and removing metabolities from the avascular cornea

the opsin (as described above) and vitamin-A (retinal)

and the crystalline lens. For details see page 207.

supplied from the blood. The 11-cis-retinal then

reunits with opsin in the rod outer segment to form

the rhodopsin. This whole process is called

PHYSIOLOGY OF VISION

rhodopsin regeneration (Fig. 2.1). Thus, the bleaching

of the rhodopsin occurs under the influence of light,

Physiology of vision is a complex phenomenon which

whereas the regeneration process is independent of

is still poorly understood. The main mechanisms

involved in physiology of vision are :

light, proceeding equally well in light and darkness.

Initiation of vision

(Phototransduction), a

function of photoreceptors (rods and cones),

Processing and transmission of visual sensation,

a function of image processing cells of retina and

visual pathway, and

Visual perception, a function of visual cortex

and related areas of cerebral cortex.

PHOTOTRANSDUCTION

The rods and cones serve as sensory nerve endings

for visual sensation. Light falling upon the retina

causes photochemical changes which in turn trigger

a cascade of biochemical reactions that result in

generation of electrical changes. Photochemical

changes occuring in the rods and cones are

essentially similar but the changes in rod pigment

(rhodopsin or visual purple) have been studied in

more detail. This whole phenomenon of conversion

of light energy into nerve impulse is known as

phototransduction.

Photochemical changes

The photochemical changes include :

Fig. 2.1. Light induced changes in rhodopsin.

Rhodopsin bleaching. Rhodopsin refers to the visual

pigment present in the rods - the receptors for night

Visual cycle. In the retina of living animals, under

(scotopic) vision. Its maximum absorption spectrum

constant light stimulation, a steady state must exist

is around 500 nm. Rhodopsin consists of a colourless

under which the rate at which the photochemicals are

protein called opsin coupled with a carotenoid called

bleached is equal to the rate at which they are

retinine (Vitamin A aldehyde or II-cis-retinal). Light

regenerated. This equilibrium between the photo-

falling on the rods converts 11-cis-retinal component

decomposition and regeneration of visual pigments

of rhodopsin into all-trans-retinal through various

is referred to as visual cycle (Fig. 2.2).

PHYSIOLOGY OF EYE AND VISION

Table 2.1. Differences in the sensitivity of M and P

cells to stimulus features

Stimulus feature

Sensitivity

M cell

P cell

Colour contrast

Yes

Luminance contrast

Higher

Lower

Spatial frequency

Lower

Higher

Temporal frequency

Higher

Lower

The visual pathway is now being considered to be

made of two lanes: one made of the large cells is called

magnocellular pathway and the other of small cells

Fig. 2.2. Visual cycle.

is called parvocellular pathway. These can be

Electrical changes

compared to two-lanes of a road. The M pathway

and P pathway are involved in the parallel processing

The activated rhodopsin, following exposure to light,

of the image i.e., analysis of different features of the

triggers a cascade of complex biochemical reactions

image.

which ultimately result in the generation of receptor

potential in the photoreceptors. In this way, the light

VISUAL PERCEPTION

energy is converted into electrical energy which is

further processed and transmitted via visual pathway.

It is a complex integration of light sense, form sense,

sense of contrast and colour sense. The receptive

PROCESSING AND TRANSMISSION OF VISUAL

field organization of the retina and cortex are used to

IMPULSE

encode this information about a visual image.

The receptor potential generated in the

1. The light sense

photoreceptors is transmitted by electrotonic

It is awareness of the light. The minimum brightness

conduction (i.e., direct flow of electric current, and

required to evoke a sensation of light is called the

not as action potential) to other cells of the retina viz.

light minimum. It should be measured when the eye

horizontal cells, amacrine cells, and ganglion cells.

is dark adapted for at least 20-30 minutes.

However, the ganglion cells transmit the visual

The human eye in its ordinary use throughout the

signals by means of action potential to the neurons

day is capable of functioning normally over an

of lateral geniculate body and the later to the primary

exceedingly wide range of illumination by a highly

visual cortex.

complex phenomenon termed as the visual

The phenomenon of processing of visual impulse

adaptation. The process of visual adaptation

is very complicated. It is now clear that visual image

primarily involves :

is deciphered and analyzed in both serial and parallel

Dark adaptation (adjustment in dim illumination),

fashion.

and

Serial processing. The successive cells in the visual

Light adaptation

(adjustment to bright

pathway starting from the photoreceptors to the cells

illumination).

of lateral geniculate body are involved in increasingly

complex analysis of image. This is called sequential

Dark adaptation

or serial processing of visual information.

It is the ability of the eye to adapt itself to decreasing

Parallel processing. Two kinds of cells can be

illumination. When one goes from bright sunshine

distinguished in the visual pathway starting from the

into a dimly-lit room, one cannot perceive the objects

ganglion cells of retina including neurons of the lateral

in the room until some time has elapsed. During this

geniculate body, striate cortex, and extrastriate cortex.

period, eye is adapting to low illumination. The time

These are large cells (magno or M cells) and small

taken to see in dim illumination is called ‘dark

cells

(parvo or P cells). There are strikinging

adaptation time’.

differences between the sensitivity of M and P cells

The rods are much more sensitive to low

to stimulus features (Table 2.1).

illumination than the cones. Therefore, rods are used

COMPREHENSIVE OPHTHALMOLOGY

more in dim light (scotopic vision) and cones in bright

where there are maximum number of cones and

light (photopic vision).

decreases very rapidly towards the periphery (Fig.

Dark adaptation curve (Fig. 2.3) plotted with

2.4). Visual acuity recorded by Snellen's test chart is

illumination of test object in vertical axis and duration

a measure of the form sense.

of dark adaptation along the horizontal axis shows

that visual threshold falls progressively in the

darkened room for about half an hour until a relative

constant value is reached. Further, the dark adaptation

curve consists of two parts: the initial small curve

represents the adaptation of cones and the remainder

of the curve represents the adaptation of rods.

Fig. 2.4. Visual acuity (form sense) in relation to the

regions of the retina: N, nasal retina; B, blind spot; F, foveal

region; and T, temporal retina.

Components of visual acuity. In clinical practice,

measurement of the threshold of discrimination of

two spatially-separated targets (a function of the

fovea centralis) is termed visual acuity. However, in

Fig. 2.3. Dark adaptation curve plotted with illumination of

theory, visual acuity is a highly complex function that

test object in vertical axis and duration of dark adaptation

consists of the following components :

along the horizontal axis.

Minimum visible. It is the ability to determine whether

When fully dark adapted, the retina is about one

an object is present or not.

lakh times more sensitive to light than when bleached.

Resolution (ordinary visual acuity). Discrimination

Delayed dark adaptation occurs in diseases of rods

of two spatially separated targets is termed resolution.

e.g., retinitis pigmentosa and vitamin A deficiency.

The minimum separation between the two points,

which can be discriminated as two, is known as

Light adaptation

minimum resolvable. Measurement of the threshold

When one passes suddenly from a dim to a brightly

of discrimination is essentially an assessment of the

lighted environment, the light seems intensely and

function of the fovea centralis and is termed ordinary

even uncomfortably bright until the eyes adapt to

visual acuity. Histologically, the diameter of a cone

the increased illumination and the visual threshold

in the foveal region is 0.004 mm and this, therefore,

rises. The process by means of which retina adapts

represents the smallest distance between two cones.

itself to bright light is called light adaptation. Unlike

It is reported that in order to produce an image of

dark adaptation, the process of light adaptation is

minimum size of 0.004mm (resolving power of the eye)

very quick and occurs over a period of 5 minutes.

the object must subtend a visual angle of 1 minute at

Strictly speaking, light adaptation is merely the

the nodal point of the eye. It is called the minimum

disappearance of dark adaptation.

angle of resolution (MAR).

2. The form sense

The clinical tests determining visual acuity measure

It is the ability to discriminate between the shapes of

the form sense or reading ability of the eye. Thus,

the objects. Cones play a major role in this faculty.

broadly, resolution refers to the ability to identify the

Therefore, form sense is most acute at the fovea,

spatial characteristics of a test figure. The test targets

PHYSIOLOGY OF EYE AND VISION

in these tests may either consist of letters (Snellen’s

1. Trichromatic theory. The trichromacy of colour

chart) or broken circle (Landolt’s ring). More complex

vision was originally suggested by Young and

targets include gratings and checker board patterns.

subsequently modified by Helmholtz. Hence it is called

Recognition. It is that faculty by virtue of which an

Young-Helmholtz theory. It postulates the existence

individual not only discriminates the spatial

of three kinds of cones, each containing a different

characteristics of the test pattern but also identifies

photopigment which is maximally sensitive to one of

the patterns with which he has had some experience.

the three primary colours viz. red, green and blue.

Recognition is thus a task involving cognitive

The sensation of any given colour is determined by

the relative frequency of the impulse from each of the

components in addition to spatial resolution. For

three cone systems. In other words, a given colour

recognition, the individual should be familiar with the

consists of admixture of the three primary colours in

set of test figures employed in addition to being able

different proportion. The correctness of the Young-

to resolve them. The most common example of

Helmholtz’s trichromacy theory of colour vision has

recognition phenomenon is identification of faces.

now been demonstrated by the identification and

The average adult can recognize thousands of faces.

chemical characterization of each of the three

Thus, the form sense is not purely a retinal

pigments by recombinant DNA technique, each

function, as, the perception of its composite form (e.g.,

having different absorption spectrum as below (Fig.

letters) is largely psychological.

2.5):

Minimum discriminable refers to spatial distinction

Red sensitive cone pigment, also known as

by an observer when the threshold is much lower

erythrolabe or long wave length sensitive (LWS)

than the ordinary acuity. The best example of minimum

cone pigment, absorbs maximally in a yellow

discriminable is vernier acuity, which refers to the

portion with a peak at 565 mm. But its spectrum

ability to determine whether or not two parallel and

extends far enough into the long wavelength to

straight lines are aligned in the frontal plane.

sense red.

Green sensitive cone pigment, also known as

3. Sense of contrast

chlorolabe or medium wavelength sensitive

It is the ability of the eye to perceive slight changes

(MWS) cone pigment, absorbs maximally in the

in the luminance between regions which are not

green portion with a peak at 535 nm.

separated by definite borders. Loss of contrast

Blue sensitive cone pigment, also known as

sensitivity results in mild fogginess of the vision.

cyanolabe or short wavelength sensitive (SWS)

Contrast sensitivity is affected by various factors

cone pigment, absorbs maximally in the blue-violet

like age, refractive errors, glaucoma, amblyopia,

portion of the spectrum with a peak at 440 nm.

diabetes, optic nerve diseases and lenticular changes.

Further, contrast sensitivity may be impaired even in

the presence of normal visual acuity.

4. Colour sense

It is the ability of the eye to discriminate between

different colours excited by light of different

wavelengths. Colour vision is a function of the cones

and thus better appreciated in photopic vision. In

dim light (scotopic vision), all colours are seen grey

and this phenomenon is called Purkinje shift.

Theories of colour vision

The process of colour analysis begins in the retina

and is not entirely a function of brain. Many theories

have been put forward to explain the colour

Fig. 2.5. Absorption spectrum of three cone pigments.

perception, but two have been particularly influential:

COMPREHENSIVE OPHTHALMOLOGY

Thus, the Young-Helmholtz theory concludes that

Colour apponency occurs at ganglion cell onward.

blue, green and red are primary colours, but the cones

According to apponent colour theory, there are

with their maximal sensitivity in the yellow portion of

two main types of colour opponent ganglion cells:

the spectrum are light at a lower threshold than green.

Red-green opponent colour cells use signals

It has been studied that the gene for human

from red and green cones to detect red/green

rhodopsin is located on chromosome 3, and the gene

contrast within their receptive field.

for the blue-sensitive cone is located on chromosome

Blue-yellow opponent colour cells obtain a

7. The genes for the red and green sensitive cones

yellow signal from the summed output of red and

are arranged in tandem array on the q arm of the X

green cones, which is contrasted with the output

chromosomes.

from blue cones within the receptive field.

2. Opponent colour theory of Hering. The opponent

colour theory of Hering points out that some colours

PHYSIOLOGY OF OCULAR

appear to be ‘mutually exclusive’. There is no such

MOTILITY AND BINOCULAR VISION

colour as ‘reddish-green’, and such phenomenon can

be difficult to explain on the basis of trichromatic

PHYSIOLOGY OF OCULAL MOTILITY

theory alone. In fact, it seems that both theories are

See page 313.

useful in that:

The colour vision is trichromatic at the level of

PHYSIOLOGY OF BINOCULAR SINGLE VISION

photoreceptors, and

See page 318.

Optics and

CHAPTER

Refraction

OPTICS

Anomalies of accommodation

Light

Presbyopia

Geometrical optics

Insufficiency of accommodation

Optics of the eye (visual optics)

Paralysis of accommodation

ERRORS OF REFRACTION

Spasm of accommodation

Hypermetropia

Myopia

DETERMINATION OF ERRORS OF

Astigmatism

REFRACTION

Anisometropia

Objective refraction

Aniseikonia

Subjective refraction

ACCOMMODATION AND ITS

ANOMALIES

SPECTACLES AND CONTACT LENSES

Accommodation

Spectacles

Mechanism

Contact lenses

Far point and near point

Range and amplitude

REFRACTIVE SURGERY

in phakic eye; and those between 600 nm and 295

OPTICS

nm in aphakic eyes.

LIGHT

GEOMETRICAL OPTICS

Light is the visible portion of the electromagnetic

The behaviour of light rays is determined by ray-

radiation spectrum. It lies between ultraviolet and

optics. A ray of light is the straight line path followed

infrared portions, from 400 nm at the violet end of the

by light in going from one point to another. The ray-

spectrum to 700 nm at the red end. The white light

optics, therefore, uses the geometry of straight lines

consists of seven colours denoted by VIBGYOR

to account for the macroscopic phenomena like

(violet, indigo, blue, green, yellow, orange and red).

rectilinear propagation, reflection and refraction. That

Light ray is the term used to describe the radius of

is why the ray-optics is also called geometrical optics.

the concentric wave forms. A group of parallel rays of

The knowledge of geometrical optics is essential

light is called a beam of light.

to understand the optics of eye, errors of refraction

Important facts to remember about light rays are :

and their correction. Therefore, some of its important

The media of the eye are uniformally permeable aspects are described in the following text.

to the visible rays between 600 nm and 390 nm.

Reflection of light

Cornea absorbs rays shorter than

295 nm.

Therefore, rays between 600 nm and 295 nm only

Reflection of light is a phenomenon of change in the

can reach the lens.

path of light rays without any change in the medium

Lens absorbs rays shorter than 350 nm. Therefore,

(Fig. 3.1). The light rays falling on a reflecting surface

rays between 600 and 350 nm can reach the retina

are called incident rays and those reflected by it are

Comprehensive OPHTHALMOLOGY

reflected rays. A line drawn at right angle to the

2. Spherical mirror. A spherical mirror (Fig. 3.3) is a

surface is called the normal.

part of a hollow sphere whose one side is silvered

Laws of reflection are (Fig. 3.1):

and the other side is polished. The two types of

1. The incident ray, the reflected ray and the normal

spherical mirrors are : concave mirror (whose

at the point of incident, all lie in the same plane.

reflecting surface is towards the centre of the sphere)

2. The angle of incidence is equal to the angle of

and convex mirror (whose reflecting surface is away

reflection.

from the centre of the sphere.

Cardinal data of a mirror (Fig. 3.3)

The centre of curvature

curvature (R) of a spherical mirror are the centre

and radius, respectively, of the sphere of which

the mirror forms a part.

Normal to the spherical mirror at any point is the

line joining that point to the centre of curvature

Pole of the mirror (P) is the centre of the reflecting

surface.

Principal axis of the mirror is the straight line

joining the pole and centre of curvature of

spherical mirror and extended on both sides.

Fig. 3.1. Laws of reflection.

Mirrors

A smooth and well-polished surface which reflects

regularly most of the light falling on it is called a mirror.

Types of mirrors

Mirrors can be plane or spherical.

1. Plane mirror. The features of an image formed by

a plane mirror (Fig. 3.2) are: (i) it is of the same size as

the object; (ii) it lies at the same distance behind the

Fig. 3.3. Cardinal points of a concave mirror.

mirror as the object is in front; (iii) it is laterally

inverted; and (iv) virtual in nature.

Principal focus (F) of a spherical mirror is a point

on the principal axis of the mirror at which, ray

incident on the mirror in a direction parallel to the

principal axis actually meet (in concave mirror) or

appear to diverge (as in convex mirror) after

reflection from the mirror.

Focal length (f) of the mirror is the distance of

principal focus from the pole of the spherical

mirror.

Images formed by a concave mirror

As a summary, Table 3.1 gives the position, size and

nature of images formed by a concave mirror for

different positions of the object. Figures 3.4 a, b, c, d,

Fig. 3.2. Image formation with a plane mirror.

e and f illustrate various situations.

Comprehensive OPHTHALMOLOGY

Refraction of light

Critical angle refers to the angle of incidence in the

Refraction of light is the phenomenon of change in

denser medium, corresponding to which angle of

the path of light, when it goes from one medium to

refraction in the rare medium is 90°. It is represented

another. The basic cause of refraction is change in

by C and its value depends on the nature of media in

the velocity of light in going from one medium to the

contact.

other.

The principle of total internal reflection is utilized

in many optical equipments; such as fibroptic lights,

Laws of refraction are (Fig. 3.5):

applanation tonometer, and gonioscope.

The incident and refracted rays are on opposite

sides of the normal and all the three are in the

same plane.

The ratio of sine of angle of incidence to the sine

of angle of refraction is constant for the part of

media in contact. This constant is denoted by the

letter n and is called

‘refractive index’ of the

medium 2 in which the refracted ray lies with

respect to medium 1 (in which the incident ray

sin

lies), i.e.,

= ¹n₂. When the medium 1 is air

sin

(or vaccum), then n is called the refractive index

of the medium 2. This law is also called Snell’s

Fig. 3.6. Refraction of light (1-1'); path of refracted

law of refraction.

ray at critical angle, c (2-2'); and total internal reflection

(3-3').

Prism

A prism is a refracting medium, having two plane

surfaces, inclined at an angle. The greater the angle

formed by two surfaces at the apex, the stronger the

prismatic effect. The prism produces displacement of

the objects seen through it towards apex (away from

the base) (Fig. 3.7). The power of a prism is measured

in prism dioptres. One prism dioptre (∆) produces

displacement of an object by one cm when kept at a

distance of one metre. Two prism dioptres of

displacement is approximately equal to one degree of

arc.

Fig. 3.5. Laws of refraction. N₁ and N₂ (normals); I (incident

ray); i (angle of incidence); R (refracted ray, bent towards

normal); r (angle of refraction); E (emergent ray, bent away

from the normal).

Total internal reflection

When a ray of light travelling from an optically- denser

medium to an optically-rarer medium is incident at an

angle greater than the critical angle of the pair of media

in contact, the ray is totally reflected back into the

denser medium (Fig. 3.6). This phenomenon is called

total internal reflection.

Fig. 3.7. Refraction by a prism.

OPTICS AND REFRACTION

Uses. In ophthalmology, prisms are used for :

lens power is taken as negative. It is measured

1. Objective measurement of angle of deviation

as reciprocal of the focal length in metres i.e. P

(Prism bar cover test, Krimsky test).

= 1/f. The unit of power is dioptre (D). One

2. Measurement of fusional reserve and diagnosis

dioptre is the power of a lens of focal length one

of microtropia.

metre.

3. Prisms are also used in many ophthalmic

Types of lenses

equipments such as gonioscope, keratometer,

Lenses are of two types: the spherical and cylindrical

applanation tonometer.

(toric or astigmatic).

4. Therapeutically, prisms are prescribed in patients

with phorias and diplopia.

1. Spherical lenses. Spherical lenses are bounded by

two spherical surfaces and are mainly of two types :

Lenses

convex and concave.

A lens is a transparent refracting medium, bounded

(i) Convex lens or plus lens is a converging lens. It

by two surfaces which form a part of a sphere

may be of biconvex, plano-convex or concavo-convex

(spherical lens) or a cylinder (cylindrical or toric lens).

(meniscus) type (Fig. 3.9).

Cardinal data of a lens (Fig. 3.8)

1. Centre of curvature (C) of the spherical lens is

the centre of the sphere of which the refracting

lens surface is a part.

2. Radius of curvature of the spherical lens is the

radius of the sphere of which the refracting

surface is a part.

Fig. 3.9. Basic forms of a convex lens: (A) biconvex; (B)

plano-convex; (C) concavo-convex.

Identification of a convex lens. (i) The convex lens is

thick in the centre and thin at the periphery (ii) An

object held close to the lens, appears magnified. (iii)

Fig. 3.8. Cardinal points of a convex lens: optical centre

When a convex lens is moved, the object seen through

(O); principal focus (F); centre of curvature (C); and principal

it moves in the opposite direction to the lens.

axis (AB).

Uses of convex lens. It is used (i) for correction of

3. The principal axis (AB) of the lens is the line

hypermetropia, aphakia and presbyopia; (ii) in oblique

joining the centres of curvatures of its surfaces.

illumination (loupe and lens) examination, in indirect

4. Optical centre (O) of the lens corresponds to the

ophthalmoscopy, as a magnifying lens and in many

nodal point of a thick lens. It is a point on the

other equipments.

principal axis in the lens, the rays passing from

Image formation by a convex lens. Table 3.2 and Fig.

where do not undergo deviation. In meniscus

3.10 provide details about the position, size and the

lenses the optical centre lies outside the lens.

nature of the image formed by a convex lens.

5. The principal focus (F) of a lens is that point on

the principal axis where parallel rays of light, after

(ii) Concave lens or minus lens is a diverging lens. It

passing through the lens, converge (in convex

is of three types: biconcave, plano-concave and

lens) or appear to diverge (in concave lens).

convexo-concave (meniscus) (Fig. 3.11).

6. The focal length (f) of a lens is the distance

between the optical centre and the principal focus.

Identification of concave lens. (i) It is thin at the centre

7. Power of a lens (P) is defined as the ability of the

and thick at the periphery. (ii) An object seen through

lens to converge a beam of light falling on the

it appears minified. (iii) When the lens is moved, the

lens. For a converging (convex) lens the power is

object seen through it moves in the same direction as

taken as positive and for a diverging (concave)

the lens.

Comprehensive OPHTHALMOLOGY

Fig. 3.10. Images formed by a convex lens for different positions of the object, (a) at infinity ; (b) beyond 2F₁; (c) at 2F₁;

(d) between F₁ and 2F₁; (e) at F₁; (f) between F₁ and optical centre of lens

Table 3.2. Images formed by a convex lens for various positions of object

No.

Position of

Nature and size

Ray

the object

the image

of the image

diagram

At infinity

At focus (F₂)

Real, very small and inverted

Fig. 3.10 (a)

Beyond 2F₁

Between F₂ and 2F₂

Real, diminished and inverted

Fig. 3.10 (b)

At 2F₁

At 2F₂

Real, same size and inverted

Fig. 3.10 (c)

Between F₁ and 2F₁

Beyond 2F₂

Real, enlarged and inverted

Fig. 3.10 (d)

At focus F₁

At infinity

Real, very large and inverted

Fig. 3.10 (e)

Between F₁ and

On the same side of

Virtual, enlarged and erect

Fig. 3.10 (f)

the optical centre

lens

of the lens

Uses of concave lens. It is used (i) for correction of

myopia; (ii) as Hruby lens for fundus examination with

slit-lamp.

Image formation by a concave lens. A concave lens

always produces a virtual, erect image of an object

(Fig. 3.12).

Fig. 3.11. Basic forms of a concave lens: biconcave (A);

plano-concave (B); and convexo-concave (C).

OPTICS AND REFRACTION

Identification of a cylindrical lens. (i) When the

cylindrical lens is rotated around its optical axis, the

object seen through it becomes distorted. (ii) The

cylindrical lens acts in only one axis, so when it is

moved up and down or sideways, the objects will move

with the lens (in concave cylinder) or opposite to the

lens (in convex cylinder) only in one direction.

Uses of cylindrical lenses. (i) Prescribed to correct

Fig. 3.12. Image formation by a concave lens.

astigmatism (ii) As a cross cylinder used to check the

2. Cylindrical lens. A cylindrical lens acts only in one

refraction subjectively.

axis i.e., power is incorporated in one axis, the other

Images formed by cylindrical lenses. Cylindrical or

axis having zero power. A cylindrical lens may be

astigmatic lens may be simple (curved in one meridian

convex (plus) or concave (minus). A convex cylindrical

only, either convex or concave), compound (curved

lens is a segment of a cylinder of glass cut parallel to

unequally in both the meridians, either convex or

its axis (Fig. 3.13A). Whereas a lens cast in a convex

concave). The compound cylindrical lens is also

cylindrical mould is called concave cylindrical lens

called sphericylinder. In mixed cylinder one meridian

(Fig. 3.13B). The axis of a cylindrical lens is parallel to

is convex and the other is concave.

that of the cylinder of which it is a segment. The

Sturm's conoid

cylindrical lens has a power only in the direction at

The configuration of rays refracted through a toric

right angle to the axis. Therefore, the parallel rays of

surface is called the Sturm’s conoid. The shape of

light after passing through a cylindrical lens do not

bundle of the light rays at different levels in Sturm's

come to a point focus but form a focal line (Fig. 3.14).

conoid (Fig. 3.15) is as follows:

At point A, the vertical rays (V) are converging more

than the horizontal rays (H); so the section here is

a horizontal oval or an oblate ellipse.

At point B, (first focus) the vertical rays have come

to a focus while the horizontal rays are still

converging and so they form a horizontal line.

At point C, the vertical rays are diverging and their

divergence is less than the convergence of the

horizontal rays; so a horizontal oval is formed here.

Fig. 3.13. Cylindrical lenses: convex (A) and concave (B).

Fig. 3.14. Refraction through a convex cylindrical lens.

Fig. 3.15. Sturm's conoid.

Comprehensive OPHTHALMOLOGY

At point D, the divergence of vertical rays is

exactly equal to the convergence of the horizontal

rays from the axis. So here the section is a circle,

which is called the circle of least diffusion.

At point E, the divergence of vertical rays is more

than the convergence of horizontal rays; so the

section here is a vertical oval.

At point F, (second focus), the horizontal rays

have come to a focus while the vertical rays are

divergent and so a vertical line is formed here.

Beyond F, (as at point G) both horizontal and

vertical rays are diverging and so the section will

always be a vertical oval or prolate ellipse.

The distance between the two foc (B and F) is

called the focal interval of Sturm.

OPTICS OF THE EYE

As an optical instrument, the eye is well compared to

a camera with retina acting as a unique kind of 'film'.

The focusing system of eye is composed of several

refracting structures which (with their refractive

indices given in parentheses) include the cornea

(1.37), the aqueous humour (1.33), the crystalline lens

(1.42), and the vitreous humour (1.33). These

constitute a homocentric system of lenses, which

when combined in action form a very strong refracting

Fig. 3.16. Cardinal points

of schematic

eye (A); and

system of a short focal length. The total dioptric

reduced

eye (B).

power of the eye is about +60 D out of which about

+44 D is contributed by cornea and +16 D by the

The principal points P₁ and P₂ lie in the anterior

crystalline lens.

chamber, 1.35 mm and 1.60 mm behind the anterior

surface of cornea, respectively.

Cardinal points of the eye

The nodal points N₁ and N₂ lie in the posterior

Listing and Gauss, while studying refraction by lens

part of lens, 7.08 mm and 7.33 mm behind the

combinations, concluded that for a homocentric

anterior surface of cornea, respectively.

lenses system, there exist three pairs of cardinal

points, which are: two principal foci, two principal

The reduced eye

points and two nodal points all situated on the

Listing's reduced eye. The optics of eye otherwise is

principal axis of the system. Therefore, the eye,

very complex. However, for understanding, Listing

forming a homocentric complex lens system, when

has simplified the data by choosing single principal

analyzed optically according to Gauss' concept can

point and single nodal point lying midway between

be resolved into six cardinal points (schematic eye).

two principal points and two nodal points,

respectively. This is called Listing's reduced eye. The

Schematic eye

simplified data of this eye (Fig. 3.16b) are as follows :

The cardinal points in the schematic eye as described

by Gullstrand are as follows (Fig. 13.16A):

Total dioptric power +60 D.

Total dioptric power is +58 D, of which cornea

The principal point (P) lies 1.5 mm behind the

contributes +43 D and the lens +15 D.

anterior surface of cornea.

The principal foci F₁ and F₂ lie 15.7 mm in front

The nodal point (N) is situated 7.2 mm behind the

of and 24.4 mm behind the cornea, respectively.

anterior surface of cornea.

OPTICS AND REFRACTION

The anterior focal point is 15.7 mm in front of the

Optical aberrations of the normal eye

anterior surface of cornea.

The eye, in common with many optical systems in

The posterior focal point (on the retina) is 24.4

practical use, is by no means optically perfect; the

mm behind the anterior surface of cornea.

lapses from perfection are called aberrations.

The anterior focal length is 17.2 mm (15.7 + 1.5)

Fortunately, the eyes possess those defects to so

and the posterior focal length is 22.9 mm (24.4 -

small a degree that, for functional purposes, their

1.5).

presence is immaterial. It has been said that despite

imperfections the overall performance of the eye is

Axes and visual angles of the eye

little short of astonishing. Physiological optical

The eye has three principal axes and three visual

defects in a normal eye include the following :

angles (Fig. 3.17).

1. Diffraction of light. Diffraction is a bending of

Axes of the eye

light caused by the edge of an aperture or the rim of a

1. Optical axis is the line passing through the

lens. The actual pattern of a diffracted image point

centre of the cornea (P), centre of the lens (N)

produced by a lens with a circular aperture or pupil is

and meets the retina (R) on the nasal side of the

a series of concentric bright and dark rings (Fig. 3.18).

fovea.

At the centre of the pattern is a bright spot known as

2. Visual axis is the line joining the fixation point

the Airy disc.

(O), nodal point (N), and the fovea (F).

3. Fixation axis is the line joining the fixation point

(O) and the centre of rotation (C).

Fig. 3.17. Axis of the eye: optical axis (AR); visual axis

(OF); fixation axis (OC) and visual angles : angle alpha

Fig. 3.18. The diffraction of light. Light brought to a focus

(ONA, between optical axis and visual axis at nodal point

does not come to a point,but gives rise to a blurred disc

N); angle kappa (OPA, between optical axis and pupillary

of light surrounded by several dark and light bands (the

line - OP); angle gamma (OCA, between optical axis and

'Airy disc').

fixation axis).

2. Spherical aberrations. Spherical aberrations occur

Visual angles (Fig. 3.17)

owing to the fact that spherical lens refracts peripheral

1. Angle alpha. It is the angle

(ONA) formed

rays more strongly than paraxial rays which in the

between the optical axis (AR) and visual axis

case of a convex lens brings the more peripheral rays

(OF) at the nodal point (N).

to focus closer to the lens (Fig. 3.19).

2. Angle gamma. It is the angle (OCA) between the

The human eye, having a power of about

optical axis (AR) and fixation axis (OC) at the

+60 D, was long thought to suffer from various

centre of rotation of the eyeball (C).

amounts of spherical aberrations. However, results

3. Angle kappa. It is the angle

(OPA) formed

from aberroscopy have revealed the fact that the

between the visual axis (OF) and pupillary line

dominant aberration of human eye is not spherical

(AP). The point P on the centre of cornea is

aberration but rather a coma-like aberration.

considered equivalent to the centre of pupil.

3. Chromatic aberrations. Chromatic aberrations

Practically only the angle kappa can be measured

result owing to the fact that the index of refraction of

and is of clinical significance. A positive angle kappa

results in pseudo-exotropia and a negative angle

any transparent medium varies with the wavelength

kappa in pseudo-esotropia.

of incident light. In human eye, which optically acts

Comprehensive OPHTHALMOLOGY

6. Coma. Different areas of the lens will form foci in

planes other than the chief focus. This produces in

the image plane a 'coma effect' from a point source of

light.

ERRORS OF REFRACTION

Emmetropia (optically normal eye) can be defined as

a state of refraction, where in the parallel rays of light

coming from infinity are focused at the sensitive layer

of retina with the accommodation being at rest

Fig. 3.19. Spherical aberration. Because there is greater

refraction at periphery of spherical lens than near centre,

(Fig. 3.21).

incoming rays of light do not truly come to a point focus.

as a convex lens, blue light is focussed slightly in

front of the red (Fig. 3.20). In other words, the

emmetropic eye is in fact slightly hypermetropic for

red rays and myopic for blue and green rays. This in

fact forms the basis of bichrome test used in subjective

refraction.

Fig. 3.21. Refraction in an emmetropic eye.

At birth, the eyeball is relatively short, having +2

to +3 hypermetropia. This is gradually reduced until

by the age of 5-7 years the eye is emmetropic and

remains so till the age of about 50 years. After this,

there is tendency to develop hypermetropia again,

which gradually increases until at the extreme of life

the eye has the same +2 to +3 with which it started.

Fig. 3.20. Chromatic aberration. The dioptric system of the

This senile hypermetropia is due to changes in the

eye is represented by a simple lens. The yellow light is

focussed on the retina, and the eye is myopic for blue, and

crystalline lens.

hypermetropic for red.

Ametropia (a condition of refractive error), is

defined as a state of refraction, when the parallel rays

4. Decentring. The cornea and lens surfaces alter the

of light coming from infinity (with accommodation at

direction of incident light rays causing them to focus

rest), are focused either in front or behind the sensitive

on the retina. Actually these surfaces are not centred

layer of retina, in one or both the meridians. The

on a common axis. The crystalline lens is usually

ametropia includes myopia, hypermetropia and

slightly decentred and tipped with respect to the axis

astigmatism. The related conditions aphakia and

of the cornea and with respect to the visual axis of

pseudophakia are also discussed here.

the eye. It has been reported that the centre of

curvature of cornea is situated about 0.25 mm below

HYPERMETROPIA

the axis of the lens. However, the effects of deviation

Hypermetropia (hyperopia) or long-sightedness is the

are usually so small that they are functionally

neglected.

refractive state of the eye wherein parallel rays of

light coming from infinity are focused behind the

5. Oblique aberration. Objects in the peripheral field

are seen by virtue of obliquely incident narrow pencil

retina with accommodation being at rest (Fig. 3.22).

of rays which are limited by the pupil. Because of

Thus, the posterior focal point is behind the retina,

this, the refracted pencil shows oblique astigmatism.

which therefore receives a blurred image.

OPTICS AND REFRACTION

Aphakia (congenital or acquired absence of lens)

and

Consecutive hypermetropia

(due to surgically

over-corrected myopia).

3. Functional hypermetropia results from paralysis

of accommodation as seen in patients with third nerve

paralysis and internal ophthalmoplegia.

Fig. 3.22. Refraction in a hypermetropic eye.

Nomenclature (components of hypermetropia)

Nomenclature for various components of the

Etiology

hypermetropia is as follows:

Hypermetropia may be axial, curvatural, index,

Total hypermetropia is the total amount of refractive

positional and due to absence of lens.

error, which is estimated after complete cycloplegia

1. Axial hypermetropia is by far the commonest

with atropine. It consists of latent and manifest

form. In this condition the total refractive power

hypermetropia.

of eye is normal but there is an axial shortening

1. Latent hypermetropia implies the amount of

of eyeball. About 1-mm shortening of the antero-

hypermetropia

(about

1D) which is normally

posterior diameter of the eye results in 3 dioptres

corrected by the inherent tone of ciliary muscle.

of hypermetropia.

The degree of latent hypermetropia is high in

2. Curvatural hypermetropia is the condition in

children and gradually decreases with age. The

which the curvature of cornea, lens or both is

latent hypermetropia is disclosed when refraction

flatter than the normal resulting in a decrease in

is carried after abolishing the tone with atropine.

the refractive power of eye. About 1 mm increase

2. Manifest hypermetropia is the remaining portion

in radius of curvature results in 6 dioptres of

of total hypermetropia, which is not corrected by

hypermetropia.

the ciliary tone. It consists of two components,

3. Index hypermetropia occurs due to decrease in

the facultative and the absolute hypermetropia.

refractive index of the lens in old age. It may also

i. Facultative hypermetropia constitutes that

occur in diabetics under treatment.

part which can be corrected by the patient's

4. Positional hypermetropia results from posteriorly

placed crystalline lens.

accommodative effort.

5. Absence of crystalline lens either congenitally or

ii. Absolute hypermetropia is the residual part

acquired (following surgical removal or posterior

of manifest hypermetropia which cannot be

dislocation) leads to aphakia — a condition of

corrected by the patient's accommodative

high hypermetropia.

efforts.

Thus, briefly:

Clinical types

Total hypermetropia = latent + manifest (facultative +

There are three clinical types of hypermetropia:

absolute).

1. Simple or developmental hypermetropia is the

Clinical picture

commonest form. It results from normal biological

variations in the development of eyeball. It includes

Symptoms

axial and curvatural hypermetropia.

In patients with hypermetropia the symptoms vary

2. Pathological hypermetropia results due to either

depending upon the age of patient and the degree of

congenital or acquired conditions of the eyeball which

refractive error. These can be grouped as under:

are outside the normal biological variations of the

1. Asymptomatic. A small amount of refractive error

development. It includes :

in young patients is usually corrected by mild

Index hypermetropia (due to acquired cortical

accommodative effort without producing any

sclerosis),

symptom.

Positional hypermetropia

(due to posterior

2. Asthenopic symptoms. At times the hypermetropia

subluxation of lens),

is fully corrected (thus vision is normal) but due

Comprehensive OPHTHALMOLOGY

to sustained accommodative efforts patient

4. Predisposition to develop primary narrow angle

develops asthenopic sysmtoms. These include:

glaucoma. The eye in hypermetropes is small

tiredness of eyes, frontal or fronto-temporal

with a comparatively shallow anterior chamber.

headache, watering and mild photophobia. These

Due to regular increase in the size of the lens

asthenopic symptoms are especially associated

with increasing age, these eyes become prone to

an attack of narrow angle glaucoma. This point

with near work and increase towards evening.

should be kept in mind while instilling mydriatics

3. Defective vision with asthenopic symptoms.

in elderly hypermetropes.

When the amount of hypermetropia is such that

it is not fully corrected by the voluntary

Treatment

accommodative efforts, then the patients complain

A. Optical treatment. Basic principle of treatment is

of defective vision which is more for near than

to prescribe convex (plus) lenses, so that the light

distance and is associated with asthenopic

rays are brought to focus on the retina (Fig. 3.23).

symptoms due to sustained accommodative

Fundamental rules for prescribing glasses in

efforts.

hypermetropia include:

4. Defective vision only. When the amount of

hypermetropia is very high, the patients usually

do not accommodate (especially adults) and there

occurs marked defective vision for near and

distance.

Signs

1. Size of eyeball may appear small as a whole.

2. Cornea may be slightly smaller than the normal.

3. Anterior chamber is comparatively shallow.

4. Fundus examination reveals a small optic disc

Fig.

3.23. Refraction in a hypermetropic eye corrected

which may look more vascular with ill-defined

with convex lens

margins and even may simulate papillitis (though

1. Total amount of hypermetropia should always be

there is no swelling of the disc, and so it is called

discovered by performing refraction under

pseudopapillitis). The retina as a whole may shine

complete cycloplegia.

due to greater brilliance of light reflections (shot

2. The spherical correction given should be

silk appearance).

comfortably acceptable to the patient. However,

5. A-scan ultrasonography (biometry) may reveal a

the astigmatism should be fully corrected.

short antero-posterior length of the eyeball.

3. Gradually increase the spherical correction at 6

Complications

months interval till the patient accepts manifest

hypermetropia.

If hypermetropia is not corrected for a long time the

4. In the presence of accommodative convergent

following complications may occur:

squint, full correction should be given at the first

1. Recurrent styes, blepharitis or chalazia may

sitting.

occur, probably due to infection introduced by

5. If there is associated amblyopia, full correction

repeated rubbing of the eyes, which is often

with occlusion therapy should be started.

done to get relief from fatigue and tiredness.

2. Accommodative convergent squint may develop

Modes of prescription of convex lenses

in children (usually by the age of 2-3 years) due

1. Spectacles are most comfortable, safe and

to excessive use of accommodation.

easy method of correcting hypermetropia.

3. Amblyopia may develop in some cases. It may be

2. Contact lenses are indicated in unilateral

anisometropic

(in unilateral hypermetropia),

hypermetropia

(anisometropia). For cosmetic

strabismic (in children developing accommodative

reasons, contact lenses should be prescribed

squint) or ametropic

(seen in children with

once the prescription has stabilised, otherwise,

uncorrected bilateral high hypermetropia).

they may have to be changed many a times.

OPTICS AND REFRACTION

B. Surgical treatment of hypermetropia is described

3. Iridodonesis i.e., tremulousness of iris can be

on page 48.

demonstrated.

4. Pupil is jet black in colour.

APHAKIA

5. Purkinje's image test shows only two images

Aphakia literally means absence of crystalline lens

(normally four images are seen- Fig. 2.10).

from the eye. However, from the optical point of view,

6. Fundus examination shows hypermetropic small

it may be considered a condition in which the lens is

disc.

absent from the pupillary area. Aphakia produces a

7. Retinoscopy reveals high hypermetropia.

high degree of hypermetropia.

Treatment

Causes

Optical principle is to correct the error by convex

1. Congenital absence of lens. It is a rare condition.

lenses of appropriate power so that the image is

formed on the retina (Fig. 3.23).

2. Surgical aphakia occurring after removal of lens

is the commonest presentation.

Modalities for correcting aphakia include: (1)

3. Aphakia due to absorption of lens matter is

spectacles, (2) contact lens, (3) intraocular lens, and

noticed rarely after trauma in children.

(4) refractive corneal surgery.

4. Traumatic extrusion of lens from the eye also

1. Spectacles prescription has been the most

constitutes a rare cause of aphakia.

commonly employed method of correcting aphakia,

5. Posterior dislocation of lens in vitreous causes

especially in developing countries. Presently, use of

optical aphakia.

aphakic spectacles is decreasing. Roughly, about +10

D with cylindrical lenses for surgically induced

Optics of aphakic eye

astigmatism are required to correct aphakia in

Following optical changes occur after removal of

previously emmetropic patients. However, exact

crystalline lens:

number of glasses will differ in individual case and

1. Eye becomes highly hypermetropic.

should be estimated by refraction. An addition of +3

to +4 D is required for near vision to compensate for

2. Total power of eye is reduced to about +44 D

loss of accommodation.

from +60 D.

3. The anterior focal point becomes 23.2 mm in front

Advantages of spectacles. It is a cheap, easy and

of the cornea.

safe method of correcting aphakia.

4. The posterior focal point is about 31 mm behind

Disadvantages of spectacles. (i) Image is magnified

the cornea i.e., about 7 mm behind the eyeball.

by 30 percent, so not useful in unilateral aphakia

(The antero-posterior length of eyeball is about

(produce diplopia). (ii) Problem of spherical and

24 mm)

chromatic aberrations of thick lenses. (iii) Field of

5. There occurs total loss of accommodation.

vision is limited. (iv) Prismatic effect of thick glasses.

(v) 'Roving ring Scotoma'

(Jack in the box

Clinical features

phenomenon). (vi) Cosmetic blemish especially in

young aphakes.

Symptoms.

1. Defective vision. Main symptom in aphakia is

2. Contact lenses. Advantages of contact lenses over

marked defective vision for both far and near due to

spectacles include: (i) Less magnification of image.

high hypermetropia and absence of accommodation.

(ii) Elimination of aberrations and prismatic effect of

2. Erythropsia and cynopsia i.e., seeing red and blue

thick glasses. (iii) Wider and better field of vision.

images. This occurs due to excessive entry of

(iv) Cosmetically more acceptable. (v) Better suited

ultraviolet and infrared rays in the absence of

for uniocular aphakia.

crystalline lens.

Disadvantages of contact lenses are: (i) more cost;

Signs of aphakia include:

(ii) cumbersome to wear, especially in old age and in

1. Limbal scar may be seen in surgical aphakia.

childhood; and (iii) corneal complications may be

2. Anterior chamber is deeper than normal.

associated.

Comprehensive OPHTHALMOLOGY

6. Visual status and refraction will vary depending

3. Intraocular lens implantation is the best available

upon the power of IOL implanted as described

method of correcting aphakia. Therefore, it is the

above.

commonest modality being employed now a days.

For details see page 195.

MYOPIA

4. Refractive corneal surgery is under trial for

Myopia or short-sightedness is a type of refractive

correction of aphakia. It includes:

error in which parallel rays of light coming from infinity

i. Keratophakia. In this procedure a lenticule

are focused in front of the retina when

prepared from the donor cornea is placed between

accommodation is at rest (Fig. 3.24).

the lamellae of patient's cornea.

ii. Epikeratophakia. In this procedure, the lenticule

prepared from the donor cornea is stitched over

the surface of cornea after removing the

epithelium.

iii. Hyperopic Lasik (see page 48)

PSEUDOPHAKIA

The condition of aphakia when corrected with an

Fig. 3.24. Refraction in a myopic eye.

intraocular lens implant (IOL) is referred to as

pseudophakia or artephakia. For types of IOLs and

Etiological classification

details of implantation techniques and complications

1. Axial myopia results from increase in antero-

see page 195.

posterior length of the eyeball. It is the

Refractive status of a pseudophakic eye depends

commonest form.

upon the power of the IOL implanted as follows :

2. Curvatural myopia occurs due to increased

1. Emmetropia is produced when the power of the

curvature of the cornea, lens or both.

IOL implanted is exact. It is the most ideal situation.

3. Positional myopia is produced by anterior

Such patients need plus glasses for near vision only.

placement of crystalline lens in the eye.

2. Consecutive myopia occurs when the IOL

4. Index myopia results from increase in the refractive

implanted overcorrects the refraction of eye. Such

index of crystalline lens associated with nuclear

patients require glasses to correct the myopia for

sclerosis.

distance vision and may or may not need glasses for

5. Myopia due to excessive accommodation occurs

near vision depending upon the degree of myopia.

in patients with spasm of accommodation.

3. Consecutive hypermetropia develops when the

Clinical varieties of myopia

under-power IOL is implanted. Such patients require

plus glasses for distance vision and additional +2 to

1. Congenital myopia

2. Simple or developmental myopia

+3 D for near vision.

Note: Varying degree of surgically-induced

3. Pathological or degenerative myopia

astigmatism is also present in pseudophakia

4. Acquired myopia which may be: (i) post-traumatic;

(ii) post-keratitic;

(iii) drug-induced,

(iv)

Signs of pseudophakia (with posterior chamber IOL).

pseudomyopia;

(v) space myopia;

(vii) night

1. Surgical scar may be seen near the limbus.

myopia; and (viii) consecutive myopia.

2. Anterior chamber is slightly deeper than normal.

3. Mild iridodonesis (tremulousness) of iris may be

1. Congenital myopia

demonstrated.

Congenital myopia is present since birth, however, it

4. Purkinje image test shows four images.

is usually diagnosed by the age of 2-3 years. Most of

5. Pupil is blackish in colour but when light is

the time the error is unilateral and manifests as

thrown in pupillary area shining reflexes are

anisometropia. Rarely, it may be bilateral. Usually

observed. When examined under magnification

the error is of about 8 to 10 which mostly remains

after dilating the pupil, the presence of IOL is

constant. The child may develop convergent squint

confirmed (see Fig. 8.26).

in order to preferentially see clear at its far point

OPTICS AND REFRACTION

(which is about 10-12 cms). Congenital myopia may

Signs

sometimes be associated with other congenital

Prominent eyeballs. The myopic eyes typically

anomalies such as cataract, microphthalmos, aniridia,

are large and somewhat prominent.

megalocornea, and congenital separation of retina.

Anterior chamber is slightly deeper than normal.

Early correction of congenital myopia is desirable.

Pupils are somewhat large and a bit sluggishly

reacting.

2. Simple myopia

Fundus is normal; rarely temporal myopic crescent

Simple or developmental myopia is the commonest

may be seen.

variety. It is considered as a physiological error not

Magnitude of refractive errror. Simple myopia

associated with any disease of the eye. Its prevalence

usually occur between 5 and 10 year of age and

increases from 2% at 5 years to 14% at 15 years of

it keeps on increasing till about 18-20 years of

age. Since the sharpest rise occurs at school going

age at a rate of about -0.5 ± 0.30 every year. In

age i.e., between 8 year to 12 years so, it is also called

simple myopia, usually the error does not exceed

school myopia.

6 to 8.

Etiology. It results from normal biological variation

Diagnosis is confirmed by performing retinoscopy

in the development of eye which may or may not be

(page 547).

genetically determined. Some factors associated with

3. Pathological myopia

simple myopia are as follows:

Pathological/degenerative/progressive myopia, as the

Axial type of simple myopia may signify just a

name indicates, is a rapidly progressive error which

physiological variation in the length of the eyeball

starts in childhood at 5-10 years of age and results in

or it may be associated with precocious

high myopia during early adult life which is usually

neurological growth during childhood.

associated with degenerative changes in the eye.

Curvatural type of simple myopia is considered

Etiology. It is unequivocal that the pathological

to be due to underdevelopment of the eyeball.

myopia results from a rapid axial growth of the eyeball

Role of diet in early childhood has also been

which is outside the normal biological variations of

reported without any conclusive results.

development. To explain this spurt in axial growth

Role of genetics. Genetics plays some role in the

various theories have been put forward. So far no

biological variation of the development of eye, as

satisfactory hypothesis has emerged to explain the

prevelance of myopia is more in children with

etiology of pathological myopia. However, it is

both parents myopic (20%) than the children with

definitely linked with (i) heredity and (ii) general

one parent myopic (10%) and children with no

growth process.

1. Role of heredity. It is now confirmed that genetic

parent myopic (5%).

factors play a major role in the etiology, as the

Theory of excessive near work in childhood was

progressive myopia is (i) familial; (ii) more common in

also put forward, but did not gain much

certain races like Chinese, Japanese, Arabs and Jews,

importance. In fact, there is no truth in the folklore

and (iii) uncommon among Negroes, Nubians and

that myopia is aggravated by close work, watching

Sudanese. It is presumed that heredity-linked growth

television and by not using glasses.

of retina is the determinant in the development of

Clinical picture

myopia. The sclera due to its distensibility follows

Symptoms

the retinal growth but the choroid undergoes

degeneration due to stretching, which in turn causes

Poor vision for distance (short-sightedness) is

degeneration of retina.

the main symptom of myopia.

2. Role of general growth process, though minor,

Asthenopic symptoms may occur in patients with

cannot be denied on the progress of myopia.

small degree of myopia.

Lengthening of the posterior segment of the globe

Half shutting of the eyes may be complained by

commences only during the period of active growth

parents of the child. The child does so to achieve

and probably ends with the termination of the active

the greater clarity of stenopaeic vision.

growth. Therefore, the factors (such as nutritional

Comprehensive OPHTHALMOLOGY

deficiency, debilitating diseases, endocrinal

disturbances and indifferent general health) which

affect the general growth process will also influence

the progress of myopia.

The etiological hypothesis for pathological myopia

is summarised in Figure 3.25:

Genetic factors

General growth process

(play major role)

(plays minor role)

↓

More growth of retina

↓

Stretching of sclera

↓

Increased axial length



↓



Degeneration of choroid

Features of

Fig. 3.26. Elongation of the eyeball posterior to equator in



pathological myopia.

↓



pathological

Degeneration of retina



myopia

Fundus examination reveals following

↓



characteristic signs :



Degeneration of vitreous

(a)

Optic disc appears large and pale and at its

temporal edge a characteristic myopic crescent

Fig. 3.25. Etiological hypothesis for pathological myopia.

is present (Fig. 3.27). Sometimes peripapillary

Clinical picture

crescent encircling the disc may be present,

Symptoms

where the choroid and retina is distracted

away from the disc margin. A super-traction

1. Defective vision. There is considerable failure in

crescent (where the retina is pulled over the

visual function as the error is usually high.

disc margin) may be present on the nasal

Further, due to progressive degenerative changes,

side.

an uncorrectable loss of vision may occur.

(b)

Degenerative changes in retina and choroid

2. Muscae volitantes i.e., floating black opacities in

are common in progressive myopia (Fig. 3.28).

front of the eyes are also complained of by many

These are characterised by white atrophic

patients. These occur due to degenerated liquified

patches at the macula with a little heaping up

vitreous.

of pigment around them. Foster-Fuchs' spot

3. Night blindness may be complained by very high

(dark red circular patch due to sub-retinal

myopes having marked degenerative changes.

neovas-cularization

and choroidal

haemorrhage) may be present at the macula.

Signs

Cystoid degeneration may be seen at the

1. Prominent eye balls. The eyes are often

periphery. In an advanced case there occurs

prominent, appearing elongated and even

total retinal atrophy, particularly in the central

simulating an exophthalmos, especially in unilateral

area.

cases. The elongation of the eyeball mainly affects

(c)

Posterior staphyloma due to ectasia of sclera

the posterior pole and surrounding area; the part

at posterior pole may be apparent as an

of the eye anterior to the equator may be normal

excavation with the vessels bending backward

(Fig. 3.26).

over its margins.

2. Cornea is large.

(d)

Degenerative changes in vitreous include:

3. Anterior chamber is deep.

liquefaction, vitreous opacities, and posterior

4. Pupils are slightly large and react sluggishly to

vitreous detachment

(PVD) appearing as

light.

Weiss' reflex.

OPTICS AND REFRACTION

Fig. 3.27. Myopic crescent.

6. Visual fields show contraction and in some cases

that clear image is formed on the retina (Fig. 3.29).

ring scotoma may be seen.

The basic rule of correcting myopia is converse

7. ERG reveals subnormal electroretinogram due to

of that in hypermetropia, i.e., the minimum

chorioretinal atrophy.

acceptance providing maximum vision should be

prescribed. In very high myopia undercorrection

Complications

is always better to avoid the problem of near

(i) Retinal detachment; (ii) complicated cataract; (iii)

vision and that of minification of images.

vitreous haemorrhage; (iv) choroidal haemorrhage (v)

Strabismus fixus convergence.

Treatment of myopia

1. Optical treatment of myopia constitutes

prescription of appropriate concave lenses, so

Fig. 3.29. Refraction in a myopic eye

corrected with concave lens.

Modes of prescribing concave lenses are

spectacles and contact lenses. Their advantages

Foster-Fuchs' spot

and disadvantages over each other are the same

as described for hypermetropia. Contact lenses

Peripapillary and

macular

are particularly justified in cases of high myopia

degeneration

as they avoid peripheral distortion and minification

produced by strong concave spectacle lens.

2. Surgical treatment of myopia is becoming very

popular now-a-days. For details see page 46.

3. General measures empirically believed to effect

Fig. 3.28. Fundus changes in pathological myopia.

the progress of myopia (unproven usefulness)

Comprehensive OPHTHALMOLOGY

include balanced diet rich in vitamins and proteins

another but the vertical meridian is more curved than

and early management of associated debilitating

the horizontal. Thus, correction of this astigmatism

disease.

will require the concave cylinders at 180° ± 20° or

4. Low vision aids (LVA) are indicated in patients

convex cylindrical lens at 90° ± 20°. This is called

of progressive myopia with advanced

'with-the-rule' astigmatism, because similar astigmatic

degenerative changes, where useful vision cannot

condition exists normally (the vertical meridian is

be obtained with spectacles and contact lenses.

normally rendered 0.25 D more convex than the

5. Prophylaxis

(genetic counselling). As the

horizontal meridian by the pressure of eyelids).

pathological myopia has a strong genetic basis,

2. Against-the-rule astigmatism refers to an

the hereditary transfer of disease may be

astigmatic condition in which the horizontal meridian

decreased by advising against marriage between

is more curved than the vertical meridian. Therefore,

two individuals with progressive myopia.

correction of this astigmatism will require the

However, if they do marry, they should not

presciption of convex cylindrical lens at 180° ± 20° or

produce children.

concave cylindrical lens at 90° ± 20° axis.

ASTIGMATISM

3. Oblique astigmatism is a type of regular

astigmatism where the two principal meridia are not

Astigmatism is a type of refractive error wherein the

the horizontal and vertical though these are at right

refraction varies in the different meridia. Consequently,

angles to one another (e.g., 45° and 135°). Oblique

the rays of light entering in the eye cannot converge

astigmatism is often found to be symmetrical (e.g.,

to a point focus but form focal lines. Broadly, there

cylindrical lens required at 30° in both eyes) or

are two types of astigmatism: regular and irregular.

complementary (e.g., cylindrical lens required at 30°

in one eye and at 150° in the other eye).

REGULAR ASTIGMATISM

4. Bioblique astigmatism. In this type of regular

The astigmatism is regular when the refractive power

astigmatism the two principal meridia are not at right

changes uniformly from one meridian to another (i.e.,

angle to each other e.g., one may be at 30^o and other

there are two principal meridia).

at 100°.

Etiology

Optics of regular astigmatism

1. Corneal astigmatism is the result of abnormalities

As already mentioned, in regular astigmatism the

of curvature of cornea. It constitutes the most

parallel rays of light are not focused on a point but

common cause of astigmatism.

form two focal lines. The configuration of rays

2. Lenticular astigmatism is rare. It may be:

refracted through the astigmatic surface (toric

i. Curvatural due to abnormalities of curvature of

surface) is called Sturm’s conoid and the distance

lens as seen in lenticonus.

between the two focal lines is known as focal interval

ii. Positional due to tilting or oblique placement of

of Sturm. The shape of bundle of rays at different

lens as seen in subluxation.

levels (after refraction through astigmatic surface) is

iii. Index astigmatism may occur rarely due to

described on page 25.

variable refractve index of lens in different meridia.

3. Retinal astigmatism due to oblique placement

Refractive types of regular astigmatism

of macula may also be seen occasionally.

Depending upon the position of the two focal lines in

relation to retina, the regular astigmatism is further

Types of regular astigmatism

classified into three types:

Depending upon the axis and the angle between the

1. Simple astigmatism, wherein the rays are focused

two principal meridia, regular astigmatism can be

on the retina in one meridian and either in front

classified into the following types :

(simple myopic astigmatism - Fig. 3.30a) or behind

1. With-the-rule astigmatism. In this type the two

(simple hypermetropic astigmatism - Fig. 3.30b) the

principal meridia are placed at right angles to one

retina in the other meridian.

OPTICS AND REFRACTION

2. Compound astigmatism. In this type the rays of

light in both the meridia are focused either in front or

behind the retina and the condition is labelled as

compound myopic or compound hypermetropic

astigmatism, respectively (Figs. 3.30c and d).

3. Mixed astigmatism refers to a condition wherein

the light rays in one meridian are focused in front and

in other meridian behind the retina (Fig. 3.30e). Thus

in one meridian eye is myopic and in another

hypermetropic. Such patients have comparatively less

symptoms as 'circle of least diffusion' is formed on

the retina (see Fig. 3.15).

Symptoms

Symptoms of regular astigmatism include: (i) defective

vision; (ii) blurring of objects; (iii) depending upon

the type and degree of astigmatism, objects may

appear proportionately elongated; and (iv) asthenopic

symptoms, which are marked especially in small

amount of astigmatism, consist of a dull ache in the

eyes, headache, early tiredness of eyes and

sometimes nausea and even drowsiness.

Signs

1. Different power in two meridia is revealed on

retinoscopy or autorefractometry.

2. Oval or tilted optic disc may be seen on

ophthalmoscopy in patients with high degree of

astigmatism.

3. Head tilt. The astigmatic patients may

(very

exceptionally) develop a torticollis in an attempt

to bring their axes nearer to the horizontal or

vertical meridians.

4. Half closure of the lid. Like myopes, the astigmatic

patients may half shut the eyes to achieve the

greater clarity of stenopaeic vision.

Investigations

1. Retinoscopy reveals different power in two

different axis (see page 548)

2. Keratometry. Keratometry and computerized

corneal topotograpy reveal different corneal

curvature in two different meridia in corneal

astigmatism (see page 554)

3. Astigmatic fan test and (4) Jackson's cross cylinder

Fig. 3.30. Types of astigmatism : simple myopic (A); simple

test. These tests are useful in confirming the power

hypermetropic (B); compound myopic (C); compound

and axis of cylindrical lenses (see pages 555, 556).

hypermetropic (D); and mixed (E).

Comprehensive OPHTHALMOLOGY

Treatment

3. Surgical treatment is indicated in extensive

1. Optical treatment of regular astigmatism comprises

corneal scarring (when vision does not improve

the prescribing appropriate cylindrical lens,

with contact lenses) and consists of penetrating

discovered after accurate refraction.

keratoplasty.

i. Spectacles with full correction of cylindrical power

and appropriate axis should be used for distance

ANISOMETROPIA

and near vision.

The optical state with equal refraction in the two eyes

ii. Contact lenses. Rigid contact lenses may correct

is termed isometropia. When the total refraction of

upto 2-3 of regular astigmatism, while soft contact

the two eyes is unequal the condition is called

lenses can correct only little astigmatism. For

anisometropia. Small degree of anisometropia is of

higher degrees of astigmatism toric contact lenses

no concern. A difference of 1 D in two eyes causes a

are needed. In order to maintain the correct axis

2 percent difference in the size of the two retinal

of toric lenses, ballasting or truncation is required.

images. A difference up to 5 percent in retinal images

2. Surgical correction of astigmatism is quite

of two eyes is well tolerated. In other words, an

effective. For details see page 48.

anisometropia up to 2.5 is well tolerated and that

IRREGULAR ASTIGMATISM

between 2.5 and 4 D can be tolerated depending upon

the individual sensitivity. However, if it is more than

It is characterized by an irregular change of refractive

4 D, it is not tolerated and is a matter of concern.

power in different meridia. There are multiple meridia

which admit no geometrical analysis.

Etiology

Etiological types

1. Congenital and developmental anisometropia

1. Curvatural irregular astigmatism is found in

occurs due to differential growth of the two

patients with extensive corneal scars or

eyeballs.

keratoconus.

2. Acquired anisometropia may occur due to

2. Index irregular astigmatism due to variable

uniocular aphakia after removal of cataractous

refractive index in different parts of the crystalline

lens or due to implantation of IOL of wrong

lens may occur rarely during maturation of

power.

cataract.

Symptoms of irregular astigmatism include:

Clinical types

Defective vision,

1. Simple anisometropia. In this, one eye is normal

Distortion of objects and

(emmetropic) and the other either myopic (simple

Polyopia.

myopic anisometropia) or hypermetropic (simple

hypermetropic anisometropia).

Investigations

2. Compound anisometropia. wherein both eyes

1. Placido's disc test reveales distorted circles (see

are either hypermetropic

(compound hyper-

page. 471)

metropic anisometropia) or myopic (compound

2. Photokerotoscopy and computerized corneal

myopic anisometropia), but one eye is having

topography give photographic record of irregular

corneal curvature.

higher refractive error than the other.

3. Mixed anisometropia. In this, one eye is myopic

Treatment

and the other is hypermetropic. This is also

1. Optical treatment of irregular astigmatism consists

called antimetropia.

of contact lens which replaces the anterior surface

4. Simple astigmatic anisometropia. When one eye

of the cornea for refraction.

is normal and the other has either simple myopic

2. Phototherapeutic keratectomy (PTK) performed

or hypermetropic astigmatism.

with excimer laser may be helpful in patients with

5. Compound astigmatic anisometropia. When both

superficial corneal scar responsible for irregular

eyes are astigmatic but of unequal degree.

astigmatism.

OPTICS AND REFRACTION

Status of binocular vision in anisometropia

Clinical types

Three possibilities are there:

Clinically, aniseikonia may be of different types (Fig.

1. Binocular single vision is present in small degree

3.31) :

of anisometropia (less than 3).

1. Symmetrical aniseikonia

2. Uniocular vision. When refractive error in one

i. Spherical, image may be magnified or minified

eye is of high degree, that eye is suppressed and

equally in both meridia (Fig. 3.31A)

develops anisometropic amblyopia. Thus, the

ii. Cylindrical, image is magnified or minified

patient has only uniocular vision.

symmetrically in one meridian (Fig. 3.31 B).

3. Alternate vision occurs when one eye is

2. Asymetrical aniseikonia

hypermetropic and the other myopic. The

i. Prismatic In it image difference increases

hypermetropic eye is used for distant vision and

progressively in one direction (Fig. 3.31C).

myopic for near.

ii. Pincushion. In it image distortion increases

progressively in both directions, as seen with

Diagnosis

high plus correction in aphakia (Fig. 3.31D).

It is made after retinoscopic examination in patients

iii. Barrel distortion. In it image distortion

with defective vision.

decreases progressively in both directions, as

seen with high minus correction (Fig. 3.31 E).

Treatment

iv. Oblique distortion. In it the size of image is

1. Spectacles. The corrective spectacles can be

same, but there occurs an oblique distortion of

tolerated up to a maximum difference of 4 D. After

shape (Fig. 3.31F).

that there occurs diplopia.

2. Contact lenses are advised for higher degrees of

Symptoms

anisometropia.

1. Asthenopia, i.e., eyeache, browache and tiredness

3. Aniseikonic glasses are also available, but their

of eyes.

clinical results are often disappointing.

2. Diplopia due to difficult binocular vision when

4. Other modalities of treatment include:

the difference in images of two eyes is more than

Intraocular lens implantation for uniocular

5 percent

aphakia.

3. Difficulty in depth perception.

Refractive corneal surgery for unilateral high

myopia, astigmatism and hypermetropia.

Treatment

Removal of clear crystalline lens for unilateral

1. Optical aniseikonia may be corrected by

very high myopia (Fucala's operation).

aniseikonic glasses, contact lenses or intraocular

lenses depending upon the situation.

ANISEIKONIA

2. For retinal aniseikonia treat the cause.

Aniseikonia is defined as a condition wherein the

3. Cortical aniseikonia is very difficult to treat.

images projected to the visual cortex from the two

retinae are abnormally unequal in size and/or shape.

ACCOMMODATION AND

Up to 5 per cent aniseikonia is well tolerated.

ITS ANOMALIES

Etiological types

1. Optical aniseikonia may occur due to either

ACCOMMODATION

inherent or acquired anisometropia of high degree.

Definition. As we know that in an emmetropic eye,

2. Retinal aniseikonia may develop due to:

parallel rays of light coming from infinity are brought

displacement of retinal elements towards the nodal

to focus on the retina, with accommodation being at

point in one eye due to stretching or oedema of

rest. However, our eyes have been provided with a

the retina.

unique mechanism by which we can even focus the

3. Cortical aniseikonia implies asymmetrical

diverging rays coming from a near object on the retina

simultaneous perception inspite of equal size of

in a bid to see clearly (Fig. 3.32). This mechanism is

images formed on the two retinae.

called accommodation. In it there occurs increase in

OPTICS AND REFRACTION

When the eye is at rest (unaccomodated), the

ciliary ring is large and keeps the zonules tense.

Because of zonular tension the lens is kept

compressed (flat) by the capsule (Fig. 3.33A).

Contraction of the ciliary muscle causes the

ciliary ring to shorten and thus releases zonular

tension on the lens capsule. This allows the

elastic capsule to act unrestrained to deform the

lens substance. The lens then alters its shape to

become more convex or conoidal (to be more

precise) (Fig. 3.33B). The lens assumes conoidal

shape due to configuration of the anterior lens

capsule which is thinner at the center and thicker

at the periphery (Fig. 3.33).

Far point and near point

The nearest point at which small objects can be seen

clearly is called near point or punctum proximum

and the distant (farthest) point is called far point

or punctum remotum.

Far point and near point of the eye vary with the

static refraction of the eye (Fig. 3.34).

In an emmetropic eye far point is infinity (Fig.

3.34A) and near point varies with age.

Fig. 3.34. Far point in emmetropic eye (A); hypermetropic

In hypermetropic eye far point is virtual and lies

eye (B); and myopic eye (C).

behind the eye (Fig. 3.34B).

In myopic eye, it is real and lies in front of the

Pathophysiology. To understand the pathophy-

eye (Fig. 3.34C).

siology of presbyopia a working knowledge about

Range and amplitude of accommodation

accommodation (as described above) is mandatory.

Range of accommodation. The distance between the

As we know, in an emmetropic eye far point is infinity

near point and the far point is called the range of

and near point varies with age (being about 7 cm at

accommodation.

the age of 10 years, 25 cm at the age of 40 years and

Amplitude of accommodation. The difference

33 cm at the age of 45 years). Therefore, at the age of

between the dioptric power needed to focus at near

10 years, amplitude of accommodation (A) = ¹⁰⁰

point (P) and far point (R) is called amplitude of

accommodation (A). Thus A = P - R.

(dioptric power needed to see clearly at near point) -

1/a (dioptric power needed to see clearly at far point)

ANOMALIES OF ACCOMMODATION

i.e., A (at age 10) = 14 dioptres; similarly A (at age 40)

Anomalies of accommodation are not uncommon.

100

These include: (1) Presbyopia, (2) Insufficiency of

= 4 dioptres.

25⁻

accommodation, (3) Paralysis of accommodation, and

Since, we usually keep the book at about 25 cm, so

(4) Spasm of accommodation.

we can read comfortably up to the age of 40 years.

PRESBYOPIA

After the age of 40 years, the near point of

accommodation recedes beyond the normal reading

Pathophysiology and causes

or working range. This condition of failing near vision

Presbyopia (eye sight of old age) is not an error of

due to age-related decrease in the amplitude of

refraction but a condition of physiological

accommodation or increase in punctum proximum

insufficiency of accommodation leading to a

progressive fall in near vision.

is called presbyopia.

Comprehensive OPHTHALMOLOGY

Causes. Decrease in the accommodative power of

3. Near point should be fixed by taking due

crystalline lens with increasing age, leading to

consideration for profession of the patient.

presbyopia, occurs due to:

4. The weakest convex lens with which an individual

1. Age-related changes in the lens which include:

can see clearly at the near point should be

Decrease in the elasticity of lens capsule, and

prescribed, since overcorrection will also result in

Progressive, increase in size and hardness

asthenopic symptoms.

(sclerosis) of lens substance which is less easily

Presbyopic spectacles may be unifocal, bifocal or

moulded.

varifocal (see page 44)

2. Age related decline in ciliary muscle power may

Surgical Treatment of presbyopia is still in infancy

also contribute in causation of presbyopia.

(see page 49)

Causes of premature presbyopia are:

1. Uncorrected hypermetropia.

INSUFFICIENCY OF ACCOMMODATION

2. Premature sclerosis of the crystalline lens.

The term insufficiency of accommodation is used

3. General debility causing pre-senile weakness of

when the accommodative power is significantly less

ciliary muscle.

than the normal physiological limits for the patient's

4. Chronic simple glaucoma.

age. Therefore, it should not be confused with

Symptoms

presbyopia in which the physiological insufficiency

1. Difficulty in near vision. Patients usually

of accommodation is normal for the patient's age.

complaint of difficulty in reading small prints (to

Causes

start with in the evening and in dim light and later

1. Premature sclerosis of lens.

even in good light). Another important complaint

of the patient is difficulty in threading a needle

2. Weakness of ciliary muscle due to systemic

etc.

causes of muscle fatigue such as debilitating

2. Asthenopic symptoms due to fatigue of the ciliary

illness, anaemia, toxaemia, malnutrition, diabetes

muscle are also complained after reading or doing

mellitus, pregnancy, stress and so on.

any near work.

3. Weakness of ciliary muscle associated with

primary open-angle glaucoma.

Treatment

Optical treatment. The treatment of presbyopia is

Clinical features

the prescription of appropriate convex glasses for

All the symptoms of presbyopia are present, but

near work.

those of asthenopia are more prominent than those

A rough guide for providing presbyopic glasses

of blurring of vision.

in an emmetrope can be made from the age of the

Treatment

patient.

1. The treatment is essentially that of the systemic

About +1 DS is required at the age of 40-45

cause.

years,

2. Near vision spectacles in the form of weakest

+1.5 DS at 45-50 years, + 2 DS at 50-55 years, and

convex lens which allows adequate vision should

+2.5 DS at 55-60 years.

be given till the power of accommodation

However, the presbyopic add should be estimated

improves.

individually in each eye in order to determine how

3. Accommodation exercises help in recovery, if the

much is necessary to provide a comfortable range.

underlying debility has passed.

Basic principles for presbyopic correction are:

1. Always find out refractive error for distance and

PARALYSIS OF ACCOMMODATION

first correct it.

2. Find out the presbyopic correction needed in

Paralysis of accommodation also known as

each eye separately and add it to the distant

cycloplegia refers to complete absence of accom-

correction.

modation.

OPTICS AND REFRACTION

Causes

Clinical features

1. Drug induced cycloplegia results due to the

1. Defective vision due to induced myopia.

effect of atropine, homatropine or other

2. Asthenopic symptoms are more marked than the

parasympatholytic drugs.

visual symptoms.

2. Internal ophthalmoplegia

(paralysis of ciliary

Diagnosis

muscle and sphincter pupillae) may result from

It is made with refraction under atropine.

neuritis associated with diphtheria, syphilis,

diabetes, alcoholism, cerebral or meningeal

Treatment

diseases.

1. Relaxation of ciliary muscle by atropine for a few

3. Paralysis of accommodation as a component of

weeks and prohibition of near work allow prompt

complete third nerve paralysis may occur due to

recovery from spasm of accommodation.

intracranial or orbital causes. The lesions may be

2. Correction of associated causative factors prevent

traumatic, inflammatory or neoplastic in nature.

recurrence.

3. Assurance and if necessary psychotherapy.

Clinical features

1. Blurring of near vision. It is the main complaint

in previously emmetropic or hypermetropic

DETERMINATION AND

patients. Blurring of near vision may not be

CORRECTION OF REFRACTIVE

marked in myopic patients.

ERRORS

2. Photophobia

(glare) due to accompanying

dilatation of pupil (mydriasis) is usually associated

For details see page 547.

with blurring of near vision.

3. Examination reveals abnormal receding of near

point and markedly decreased range of

SPECTACLES AND CONTACT

accommodation.

LENSES

Treatment

1. Self-recovery occurs in drug-induced paralysis

SPECTACLES

and in diphtheric cases (once the systemic disease

The lenses fitted in a frame constitute the spectacles.

is treated).

It is a common, cheap and easy method of prescribing

2. Dark-glasses are effective in reducing the glare.

corrective lenses in patients with refractive errors and

3. Convex lenses for near vision may be prescribed

presbyopia. Some important aspects of the spectacles

if the paralysis is permanent.

are as follows:

SPASM OF ACCOMMODATION

Lens materials

Spasm of accommodation refers to exertion of

1. Crown glass of refractive index 1.5223 is very

abnormally excessive accommodation.

commonly used for spectacles. It is ground to the

Causes

appropriate curvature and then polished to await

1. Drug induced spasm of accommodation is known

the final cutting that will enable it to fit the

to occur after use of strong miotics such as

desired spectacle frame.

echothiophate and DFP.

2. Resin lenses made of allyl diglycol carbonate is

2. Spontaneous spasm of accommodation is

an alternative to crown glass. The resin lenses

occasionally found in children who attempt to

are light, unbreakable and scratch resistant.

compensate for a refractive anomaly that impairs

3. Plastic lenses are readily prepared by moulding.

their vision. It usually occurs when the eyes are

They are unbreakable and light weight but have

used for excessive near work in unfavourable

the disadvantages of being readily scratched and

circumstances such as bad illumination bad

warped.

reading position, lowered vitality, state of neurosis,

4. Triplex lenses are also light, they will shatter but

mental stress or anxiety.

not splinter.

Comprehensive OPHTHALMOLOGY

Lens shapes

transmit and provide comfort, safety and cosmetic

1. Meniscus lenses are used for making spectacles

effect. They are particularly prescribed in patients

in small or moderate degree of refractive errors.

with albinism, high myopia and glare prone patients.

The standard curved lenses are ground with a

Good tinted glasses should be dark enough to absorb

concave posterior surface

(-1.25 D in the

60-80 percent of the incident light in the visible part

periscopic type or -6.0 D in the deep meniscus

of the spectrum and almost all of the ultraviolet and

type) and the spherical correction is then added

infrared rays.

to the anterior surface.

Photochromatic lenses alter their colour according

2. Lenticular form lenses are used for high plus and

to the amount of ultraviolet exposure. These lenses

high minus lenses. In this type the central portion

do not function efficiently indoors and in

is corrective and the peripheral surfaces are parallel

automobiles.

to one another.

3. Aspheric lenses are also used to make high plus

Centring and decentring

aphakic lenses by modifying the lens curvature

The visual axis of the patient and the optical centre

peripherally to reduce aberrations and provide

of the spectacle lens should correspond, otherwise

better peripheral vision.

prismatic effect will be introduced. The distance

between the visual axes is measured as interpupillary

Single versus multiple power lenses

distance (IPD). Decentring of the lens is indicated

1. Single vision lens refers to a lens having the

where prismatic effect is required. One prism dioptre

same corrective power over the entire surface.

effect is produced by 1 cm decentring of a 1 D lens.

These are used to correct myopia, hypermetropia,

Reading glasses should be decentred by about 2.5

astigmatism or presbyopia.

mm medially and about 6.5 mm downward as the eyes

2. Bifocal lenses have different powers to upper

are directed down and in during reading.

(for distant vision) and lower (for near vision)

segments. Different styles of bifocal lenses are

Frames

shown in Fig. 3.35.

The spectacle frame selected should be comfortable

3. Trifocal lenses have three portions, upper (for

i.e. neither tight nor loose, light in weight and should

distant vision), middle

(for intermediate range

not put pressure on the nose or temples of the patient,

vision) and lower (for near vision).

and should be of optimum size. In children large

4. Multifocal (varifocal) or progressive lenses having

glasses are recommended to prevent viewing over

many portions of different powers are also

the spectacles. Ideally, the lenses should be worn

available.

15.3 mm from the cornea (the anterior focal plane of

Tinted lenses

eye), as at this distance the images formed on the

retina are of the same size as in emmetropia.

Tinted glasses reduce the amount of light they

CONTACT LENSES

Contact lens is an artificial device whose front surface

substitutes the anterior surface of the cornea.

Therefore, in addition to correction of refractive error,

the irregularities of the front surface of cornea can

also be corrected by the contact lenses.

Parts, curves, and nomenclature for contact lens

To understand the contact lens specifications

following standard nomenclature has been recom-

mended (Fig. 3.36).

1. Diameters of the lens are as follows :

Fig. 3.35. Bifocal lenses. (A) two-piece; (B) cemented sup-

i. Overall diameter (OD) of the lens is the linear

plementary wafer; (C) inserted wafer; (D) fused; (E) solid.

OPTICS AND REFRACTION

measurement of the greatest distance across the

5. Thickness of the lens. It is usually measured in the

physical boundaries of lens. It is expressed in

centre of the lens and varies depending upon the

millimetres. (It should not be confused as being

posterior vertex power of the lens.

twice the radius of curvature).

6. Tint. It is the colour of the lens.

Types of contact lenses

Depending upon the nature of the material used in

their manufacturing, the contact lenses can be divided

into following three types:

1. Hard lenses,

2. Rigid gas permeable lenses, and

3. Soft lenses.

1. Hard lenses are manufactured from PMMA

(polymethylmethacrylate). The PMMA has a high

optical quality, stability and is light in weight, non-

toxic, durable and cheap. The hard corneal lenses

have a diameter of 8.5-10 mm. Presently these are not

used commonly.

Fig. 3.36. A contact lens.

Disadvantages of PMMA hard contact lenses. (i)

PMMA is practically impermeable to O₂ thus

ii. Optic zone diameter (OZ) is the dimension of the

restricting the tolerance. (ii) Being hard, it can cause

central optic zone of lens which is meant to focus

corneal abrasions. (iii) Being hydrophobic in nature,

rays on retina.

resists wetting but a stable tear film can be formed

2. Curves of the lens are as follows :

over it.

i. Base curve (BC) or central posterior curve (CPC)

is a curve on the back surface of the lens to fit

Note : PMMA contact lenses are sparingly used in

the front surface of cornea.

clinical practice because of poor patient acceptance.

ii. Peripheral curves. These are concentric to base

2. Rigid gas permeable (RGP) lenses are made up of

curve and include intermediate posterior curve

materials which are permeable to oxygen. Basically

(IPC) and peripheral posterior curve (PPC).

these are also hard, but somehow due to their O₂

These are meant to serve as reservoir of tears

permeability they have become popular by the name

and to form a ski for lens movements.

of semisoft lenses. Gas permeable lenses are

iii. Central anterior curve (CAC) or front curve (FC)

commonly manufactured from copolymer of PMMA

is the curve on the anterior surface of the optical

and silicone containing vinyl monomer. Cellulose

zone of the lens. Its curvature determines the

acetate butyrate (CAB), a class of thermoplastic

power of contact lens.

material derived from special grade wood cellulose

iv. Peripheral anterior curve (PAC) is a slope on

has also been used, but is not popular.

the periphery of anterior surface which goes up

to the edge.

3. Soft lenses are made up of HEMA (hydroxyme-

v. Intermediate anterior curve (IAC) is fabricated

thymethacrylate). These are made about 1-2 mm larger

only in the high power minus and plus lenses. It

than the corneal diameter. Advantages: Being soft

lies between the CAC and PAC.

and oxygen permeable, they are most comfortable and

3. Edge of the lens. It is the polished and blended

so well tolerated. Disadvantages include problem of

union of the peripheral posterior and anterior curves

wettability, proteinaceous deposits, getting cracked,

of the lens.

limited life, inferior optical quality, more chances of

4. Power of the lens. It is measured in terms of

corneal infections and cannot correct astigmatism of

posterior vertex power in dioptres.

more than 2 dioptres.

Comprehensive OPHTHALMOLOGY

Note: In clinical practice soft lenses are most

scars (colour contact lenses); (ii) ptosis (haptic

frequently prescribed.

contact lens); and (iii) cosmetic scleral lenses in

phthisis bulbi.

Indications of contact lens use

7. Occupational indications include use by (i)

1. Optical indications include anisometropia,

sportsmen; (ii) pilots; and (iii) actors.

unilateral aphakia, high myopia, keratoconus and

irregular astigmatism. Optically they can be used by

Contraindications for contact lens use

every patient having refractive error for cosmetic

(i) Mental incompetence, and poor motivation; (ii)

purposes.

chronic dacryocystitis; (iii) chronic blepharitis and

Advantages of contact lenses over spectacles: (i)

recurrent styes; (iv) chronic conjunctivitis; (v) dry-

Irregular corneal astigmatism which is not possible

eye syndromes; (vi) corneal dystrophies and

to correct with glasses can be corrected with contact

degenerations; and (vii) recurrent diseases like

lenses. (ii) Contact lenses provide normal field of

episcleritis, scleritis and iridocyclitis.

vision. (iii) Aberrations associated with spectacles

Principles of fitting and care of lenses

(such as peripheral aberrations and prismatic

distortions) are eliminated. (iv) Binocular vision can

It is beyond the scope of this chapter. Interested

be retained in high anisometropia (e.g., unilateral

readers are advised to consult some textbook on

aphakia) owing to less magnification of the retinal

contact lenses.

image. (v) Rain and fog do not condense upon contact

lenses as they do on spectacles. (vi) Cosmetically

REFRACTIVE SURGERY

more acceptable especially by females and all patients

with thick glasses in high refractive errors.

Surgery to correct refractive errors has become very

2. Therapeutic indications are as follows :

popular. It should be performed after the error has

i. Corneal diseases e.g., non-healing corneal ulcers,

stabilized; preferably after 20 years of age. Various

bullous keratopathy, filamentary keratitis and

surgical techniques in vogue are described below:

recurrent corneal erosion syndrome.

ii. Diseases of iris such as aniridia, coloboma and

Refractive surgery of myopia

albinism to avoid glare.

1. Radial keratotomy (RK) refers to making deep

iii. In glaucoma as vehicle for drug delivery.

(90 percent of corneal thickness) radial incisions in

iv. In amblyopia, opaque contact lenses are used

the peripheral part of cornea leaving the central 4 mm

for occlusion.

optical zone (Fig 3.37). These incisions on healing;

v. Bandage soft contact lenses are used following

flatten the central cornea thereby reducing its

keratoplasty and in microcorneal perforation.

refractive power. This procedure gives very good

3. Preventive indications include (i) prevention of

correction in low to moderate myopia (2 to 6 D).

symblepharon and restoration of fornices in chemical

Disadvantages. Note: Because of its disadvantages

burns; (ii) exposure keratitis; and (iii) trichiasis.

RK is not recommended presently. (i) Cornea is

4. Diagnostic indications include use during (i)

weakened, so chances of globe rupture following

gonioscopy; (ii) electroretinography; (iii) examination

trauma are more after RK than after PRK. This point is

of fundus in the presence of irregular corneal

particularly important for patients who are at high

astigmatism; (iv) fundus photography; (v) Goldmann's

risk of blunt trauma, e.g., sports persons, athletes

3 mirror examination.

and military personnel. (ii) Rarely, uneven healing may

5. Operative indications. Contact lenses are used

lead to irregular astigmatism. (iii) Patients may feel

during (i) goniotomy operation for congenital

glare at night.

glaucoma; (ii) vitrectomy; and (iii) endocular

2. Photorefractive keratectomy (PRK). In this

photocoagulation.

technique, to correct myopia a central optical zone of

6. Cosmetic indications include (i) unsightly corneal

anterior corneal stroma is photoablated using

OPTICS AND REFRACTION

Fig. 3.37. Radial keratotomy. (A) configuration of radial

incisions; (B) depth of incision.

Fig.

3.39. Procedure of laser in-situ keratomileusis

(LASIK).

excimer laser (193-nm UV flash) to cause flattening

of the central cornea (Fig. 3.38). Like RK, the PRK

Patient selection criteria are:

also gives very good correction for -2 to -6 D of

Patients above 20 years of age,

myopia.

Stable refraction for at least 12 months.

Disadvantages. Note: Because of its disadvantages

Motivated patient.

PRK is not recommended presently: (i) Postoperative

Absence of corneal pathology. Presence of ectasia

recovery is slow. Healing of the epithelial defect may

or any other corneal pathology and a corneal

delay return of good vision and patient may

experience pain or discomfort for several weeks. (ii)

thickness less than

450 mm is an absolute

There may occur some residual corneal haze in the

contraindication for LASIK.

centre affecting vision. (iii) PRK is more expensive

Advances in LASIK. Recently many advances have

than RK.

been made in LASIK surgery. Some of the important

3. Laser in-situ keratomileusis (LASIK). In this

advances are:

technique first a flap of 130-160 micron thickness of

Customized (C) LASIK. C-LASIK is based on the

anterior corneal tissue is raised. After creating a

wave front technology. This technique, in addition

corneal flap midstromal tissue is ablated directly with

to spherical and cylindrical correction, also

an excimer laser beam, ultimately flattening the cornea

corrects the aberrations present in the eye and

(Fig. 3.39). Currently this procedure is being

considered the refractive surgery of choice for myopia

gives vision beyond 6/6 i.e., 6/5 or 6/4

of up to - 12 D.

Epi-(E) LASIK. In this technique instead of

corneal stromal flap only the epithelial sheet is

separated mechanically with the use of a

customized device (Epiedge Epikeratome). Being

an advanced surface ablation procedure, it is

devoid of complications related to corneal stromal

flap.

Advantages of LASIK. (i) Minimal or no postoperative

pain. (ii) Recovery of vision is very early as compared

to PRK. (iii) No risk of perforation during surgery and

later rupture of globe due to trauma unlike RK.

(iv) No residual haze unlike PRK where subepithelial

scarring may occur. (v) LASIK is effective in

Fig. 3.38. Photorefractive keratectomy (PRK) for myopia

as seen (A) from front; (B) in cross section.

correcting myopia of - 12 D.

Comprehensive OPHTHALMOLOGY

Disadvantages. 1. LASIK is much more expensive.

1. Holmium laser thermoplasty has been used for

2. It requires greater surgical skill than RK and PRK.

low degree of hyperopia. In this technique, laser spots

3. There is potential risk of flap related complications

are applied in a ring at the periphery to produce central

which include (i) intraoperative flap amputation,

steepening. Regression effect and induced

(ii) wrinkling of the flap on repositioning,

astigmatism are the main problems.

(iii) postoperative flap dislocation/subluxation,

2. Hyperopic PRK using excimer laser has also been

(iv) epithelization of flap-bed interface, and

tried. Regression effect and prolonged epithelial

(v) irregular astigmatism.

healing are the main problems encountered.

4. Extraction of clear crystalline lens (Fucala's

3. Hyperopic LASIK is effective in correcting

operation) has been advocated for myopia of -16 to

hypermetropia upto +4D.

-18 D, especially in unilateral cases. Recently, clear

4. Conductive keratoplasty (CK) is nonablative and

lens extraction with intraocular lens implantion of

nonincisional procedure in which cornea is steepened

appropriate power is being recommended as the

by collagen shrinkage through the radiofrequency

refractive surgery for myopia of more than 12 D.

energy applied through a fine tip inserted into the

5. Phakic intraocular lens or intraocular contact lens

peripheral corneal stroma in a ring pattern. This

(ICL) implantation is also being considered for

technique is effective for correcting hyperopia of upto

correction of myopia of >12D. In this technique, a

3D.

special type of intraocular lens is implanted in the

anterior chamber or posterior chamber anterior to the

Refractive surgery for astigmatism

natural crystalline lens.

Refractive surgical techniques employed for myopia

6. Intercorneal ring (ICR) implantation into the

can be adapted to correct astigmatism alone or

peripheral cornea at approximately 2/3 stromal depth

simultaneously with myopia as follows:

is being considered. It results in a vaulting effect that

1. Astigmatic keratotomy (AK) refers to making

flattens the central cornea, decreasing myopia. The

ICR procedure has the advantage of being reversible.

transverse cuts in the mid periphery of the steep

corneal meridian (Fig. 3.40). AK can be performed

7. Orthokeratology a non-surgical reversible method

of molding the cornea with overnight wear unique

alone (for astigmatism only) or along with RK (for

rigid gas permeable contact lenses, is also being

associated myopia).

considered for correction of myopia upto -5D. It can

2. Photo-astigmatic refractive keratotomy (PARK)

be used even in the patients below 18 year of age.

is performed using excimer laser.

3. LASIK procedure can also be adapted to correct

Refractive surgery for hyperopia

astigmatism upto 5D.

In general, refractive surgery for hyperopia is not as

effective or reliable as for myopia. However, following

Management of post-keratoplasty astigmatism

procedures are used:

1. Selective removal of sutures in steep meridians

Fig. 3.40. Astigmatic keratotomy. (A) showing flat and deep meridians of cornea; (B) paired transverse incisions to flattern

the steep meridian; (C) showing correction of astigmatism after astigmatic keratotomy.

OPTICS AND REFRACTION

may improve a varying degree of astigmatism and

presbyopia in one eye. Principle is same as for

should be tried first of all.

correction of hypermetropia (see page 48).

Scleral expansion procedures are being tried,

Note: Other procedures mentioned below should be

but results are controversial.

performed only after all the sutures are out and

LASIK-PARM i.e., LASIK by Presbyopia Avalos

refraction is stable.

Rozakis Method is a technique undertrial in which

2. Arcuate relaxing incisions in the donor cornea

the shape of the cornea is altered to have two

along the steep meridian may correct astigma-

concentric vision zones that help the presbyopic

tism up to 4-6 D.

patient to focus on near and distant objects.

3. Relaxing incisions combined with compression

Bifocal or multifocal or accommodating IOL

sutures may correct astigmatism up to 10 D.

implantation after lens extraction especially in

4. Corneal wedge resection with suture closure of

patients with cataract or high refractive errors

the wound may be performed in the flat meridian

correct far as well as near vision.

to correct astigmatism greater than 10 D.

Monovision with intraocular lenses, i.e.,

5. LASIK procedure can also be adopted to correct

correction of one eye for distant vision and other

post-keratoplasty astigmatism.

for near vision with IOL implantation after bilateral

Refractive surgery for presbyopia

cataract extraction also serves as a solution for

Refractive surgery for presbyopia, still under trial,

far and near correction.

includes :

Anterior ciliary sclerotomy (ACS), with tissue

Monovision LASIK, i.e., one eye is corrected for

barriers is currently under trial. With initial

distance and other is made slightly near sighted.

encouraging results, multi-site clinical studies are

Monovision conductive keratoplasty

(CK) is

planned for the US and Europe to evaluate this

being considered increasingly to correct

technique.

Diseases of the

CHAPTER

Conjunctiva

APPLIED ANATOMY

DEGENERATIVE CONDITIONS

Parts

Pinguecula

Pterygium

Structure

Concretions

Glands

SYMPTOMATIC CONDITIONS

INFLAMMATIONS OF CONJUNCTIVA

Hyperaemia

Infective conjunctivitis

Chemosis

Ecchymosis

- Bacterial

Xerosis

- Chlamydial

Discoloration

- Viral

CYSTS AND TUMOURS

Allergic conjunctivitis

Cysts of conjunctiva

Granulomatous conjunctivitis

Tumours of conjunctiva

ii. Tarsal conjunctiva is thin, transparent and highly

APPLIED ANATOMY

vascular. It is firmly adherent to the whole tarsal

plate in the upper lid. In the lower lid, it is

The conjunctiva is a translucent mucous membrane

adherent only to half width of the tarsus. The

which lines the posterior surface of the eyelids and

tarsal glands are seen through it as yellow streaks.

anterior aspect of eyeball. The name conjunctiva

iii.Orbital part of palpebral conjunctiva lies loose

(conjoin: to join) has been given to this mucous

between the tarsal plate and fornix.

membrane owing to the fact that it joins the eyeball

2. Bulbar conjunctiva. It is thin, transparent and lies

to the lids. It stretches from the lid margin to the

loose over the underlying structures and thus can be

limbus, and encloses a complex space called

moved easily. It is separated from the anterior sclera

conjunctival sac which is open in front at the

by episcleral tissue and Tenon's capsule. A 3-mm ridge

palpebral fissure.

of bulbar conjunctiva around the cornea is called

Parts of conjunctiva

limbal conjunctiva. In the area of limbus, the

Conjunctiva can be divided into three parts (Fig. 4.1):

conjunctiva, Tenon's capsule and the episcleral tissue

1. Palpebral conjunctiva. It lines the lids and can be

are fused into a dense tissue which is strongly

adherent to the underlying corneoscleral junction.

subdivided into marginal, tarsal and orbital

conjunctiva.

At the limbus, the epithelium of conjunctiva becomes

i. Marginal conjunctiva extends from the lid margin

continuous with that of cornea.

3. Conjunctival fornix. It is a continuous circular

to about 2 mm on the back of lid up to a shallow

cul-de-sac which is broken only on the medial side

groove, the sulcus subtarsalis. It is actually a

by caruncle and the plica semilunaris. Conjunctival

transitional zone between skin and the conjunctiva

fornix joins the bulbar conjunctiva with the palpebral

proper.

Comprehensive OPHTHALMOLOGY

Fig. 4.1. Parts of conjunctiva and conjunctival glands.

conjunctiva. It can be subdivided into superior,

Tarsal conjunctiva has

2-layered epithelium:

inferior, medial and lateral fornices.

superficial layer of cylindrical cells and a deep

layer of flat cells.

Structure of conjunctiva

Fornix and bulbar conjunctiva have 3-layered

Histologically, conjunctiva consists of three layers

epithelium: a superficial layer of cylindrical cells,

namely, (1) epithelium, (2) adenoid layer, and (3)

middle layer of polyhedral cells and a deep layer

fibrous layer (Fig. 4.2).

of cuboidal cells.

1. Epithelium. The layer of epithelial cells in

Limbal conjunctiva has again many layered (5 to

conjunctiva varies from region to region and in its

6) stratified squamous epithelium.

different parts as follows:

2. Adenoid layer. It is also called lymphoid layer

Marginal conjunctiva has

5-layered stratified

and consist s of fine connective tissue reticulum in

squamous type of epithelium.

the meshes of which lie lymphocytes. This layer is

DISEASES OF THE CONJUNCTIVA

1. Mucin secretory glands. These are goblet cells

(the unicellular glands located within the epithelium),

crypts of Henle (present in the tarsal conjunctiva)

and glands of Manz (found in limbal conjunctiva).

These glands secrete mucus which is essential for

wetting the cornea and conjunctiva.

2. Accessory lacrimal glands. These are:

Glands of Krause (present in subconjunctival

connective tissue of fornix, about 42 in upper

fornix and 8 in lower fornix) and

Glands of Wolfring

(present along the upper

border of superior tarsus and along the lower

border of inferior tarsus).

Plica semilunaris

It is a pinkish crescentric fold of conjunctiva, present

in the medial canthus. Its lateral free border is

concave. It is a vestigeal structure in human beings

and represents the nictitating membrane (or third

eyelid) of lower animals.

Caruncle

The caruncle is a small, ovoid, pinkish mass, situated

in the inner canthus, just medial to the plica

semilunaris. In reality, it is a piece of modified skin

and so is covered with stratified squamous epithelium

and contains sweat glands, sebaceous glands and

hair follicles.

Blood supply of conjunctiva

Arteries supplying the conjunctiva are derived from

Fig. 4.2. Microscopic structure of conjunctiva showing thr-

three sources (Fig. 4.3): (1) peripheral arterial arcade

ee layers (A) and arrangement of epithelial cells in different

of the eyelid; (2) marginal arcade of the eyelid; and

regions of conjunctiva (B).

(3) anterior ciliary arteries.

most developed in the fornices. It is not present since

Palpebral conjunctiva and fornices are supplied

birth but develops after 3-4 months of life. For this

by branches from the peripheral and marginal

reason, conjunctival inflammation in an infant does

arterial arcades of the eyelids.

not produce follicular reaction.

Bulbar conjunctiva is supplied by two sets of

3. Fibrous layer. It consists of a meshwork of

vessels: the posterior conjunctival arteries which

collagenous and elastic fibres. It is thicker than the

are branches from the arterial arcades of the

adenoid layer, except in the region of tarsal

eyelids; and the anterior conjunctival arteries

conjunctiva, where it is very thin. This layer contains

which are the branches of anterior ciliary arteries.

vessels and nerves of conjunctiva. It blends with the

Terminal branches of the posterior conjunctival

underlying Tenon's capsule in the region of bulbar

arteries anastomose with the anterior conjunctival

conjunctiva.

arteries to form the pericorneal plexus.

Veins from the conjunctiva drain into the venous

Glands of conjunctiva

plexus of eyelids and some around the cornea into

The conjunctiva contains two types of glands

the anterior ciliary veins.

(Fig. 4.1):

Lymphatics of the conjunctiva are arranged in two

Comprehensive OPHTHALMOLOGY

Fig. 4.3. Blood supply of conjunctiva.

layers: a superficial and a deep. Lymphatics from the

3. Irritative conjunctivitis.

lateral side drain into preauricular lymph nodes and

4. Keratoconjunctivitis associated with diseases of

those from the medial side into the submandibular

skin and mucous membrane.

lymph nodes.

5. Traumatic conjunctivitis.

6. Keratoconjunctivitis of unknown etiology.

Nerve supply of conjunctiva

Clinical classification

A circumcorneal zone of conjunctiva is supplied by

Depending upon clinical presentation, conjunctivitis

the branches from long ciliary nerves which supply

can be classified as follows:

the cornea. Rest of the conjunctiva is supplied by the

Acute catarrhal or mucopurulent conjunctivitis.

branches from lacrimal, infratrochlear, supratrochlear,

Acute purulent conjunctivitis

supraorbital and frontal nerves.

Serous conjunctivitis

Chronic simple conjunctivitis

Angular conjunctivitis

INFLAMMATIONS OF

Membranous conjunctivitis

CONJUNCTIVA

Pseudomembranous conjunctivitis

Papillary conjunctivitis

Inflammation of the conjunctiva (conjunctivitis) is

Follicular conjunctivitis

classically defined as conjunctival hyperaemia

10. Ophthalmia neonatorum

associated with a discharge which may be watery,

11. Granulomatous conjunctivitis

mucoid, mucopurulent or purulent.

12. Ulcerative conjunctivitis

13. Cicatrising conjunctivitis

Etiological classification

To describe different types of conjunctivitis, a mixed

1. Infective conjunctivitis: bacterial, chlamydial, viral,

approach has been adopted, i.e., some varieties of

fungal, rickettsial, spirochaetal, protozoal, parasitic

conjunctivitis are described by their etiological names

etc.

and others by their clinical names. Only common

2. Allergic conjunctivitis.

varieties of clinical interest are described here.

DISEASES OF THE CONJUNCTIVA

INFECTIVE CONJUNCTIVITIS

Moraxella lacunate (Moraxella Axenfeld bacillus)

is most common cause of angular conjunctivitis

Infective conjunctivitis, i.e., inflammation of the

and angular blepharoconjunctivitis.

conjunctiva caused by microorganisms is the

Pseudomonas pyocyanea is a virulent organism.

commonest variety. This is in spite of the fact that

the conjunctiva has been provided with natural

It readily invades the cornea.

protective mechanisms in the form of :

Neisseria gonorrhoeae typically produces acute

Low temperature due to exposure to air,

purulent conjunctivitis in adults and ophthalmia

Physical protection by lids,

neonatorum in new born. It is capable of invading

Flushing action of tears,

intact corneal epithelium.

Antibacterial activity of lysozymes and

Neisseria meningitidis

(meningococcus) may

Humoral protection by the tear immunoglobulins.

produce mucopurulent conjunctivitis.

Corynebacterium diphtheriae causes acute

BACTERIAL CONJUNCTIVITIS

membranous conjunctivitis. Such infections are

rare now-a-days.

There has occurred a relative decrease in the

incidence of bacterial conjunctivitis in general and

C. Mode of infection. Conjunctiva may get infected

those caused by gonococcus and corynebacterium

from three sources, viz, exogenous, local surrounding

diphtheriae in particular. However, in developing

structures and endogenous, by following modes :

countries it still continues to be the commonest type

1. Exogenous infections may spread: (i) directly

of conjunctivitis. It can occur as sporadic cases and

through close contact, as air-borne infections or

as epidemics. Outbreaks of bacterial conjunctivitis

as water-borne infections;

(ii) through vector

epidemics are quite frequent during monsoon season.

transmission (e.g., flies); or (iii) through material

transfer such as infected fingers of doctors,

Etiology

nurses, common towels, handkerchiefs, and

A. Predisposing factors for bacterial conjunctivitis,

infected tonometers.

especially epidemic forms, are flies, poor hygienic

2. Local spread may occur from neighbouring

conditions, hot dry climate, poor sanitation and dirty

structures such as infected lacrimal sac, lids, and

habits. These factors help the infection to establish,

nasopharynx. In addition to these, a change in

as the disease is highly contagious.

the character of relatively innocuous organisms

B. Causative organisms. It may be caused by a wide

present in the conjunctival sac itself may cause

range of organisms in the following approximate order

infections.

of frequency :

3. Endogenous infections may occur very rarely

Staphylococcus aureus is the most common cause

through blood e.g., gonococcal and meningoco-

of bacterial conjunctivitis and blepharo-

ccal infections.

conjunctivitis.

Pathology

Staphylococcus epidermidis is an innocuous flora

of lid and conjunctiva. It can also produce

Pathological changes of bacterial conjunctivitis

blepharoconjunctivitis.

consist of :

Streptococcus pneumoniae

(pneumococcus)

1. Vascular response. It is characterised by

produces acute conjunctivitis usually associated

congestion and increased permeability of the

with petechial subconjunctival haemorrhages. The

conjunctival vessels associated with proliferation

disease has a self-limiting course of 9-10 days.

of capillaries.

Streptococcus pyogenes (haemolyticus) is virulent

2. Cellular response. It is in the form of exudation

and usually produces pseudomembranous

of polymorphonuclear cells and other

conjunctivitis.

inflammatory cells into the substantia propria of

Haemophilus influenzae (aegyptius, Koch- Weeks

conjunctiva as well as in the conjunctival sac.

bacillus). It classically causes epidemics of

3. Conjunctival tissue repsonse. Conjunctiva

mucopurulent conjunctivitis, known as ‘red-eye’

becomes oedematous. The superficial epithelial

especially in semitropical countries.

cells degenerate, become loose and even

Comprehensive OPHTHALMOLOGY

desquamate. There occurs proliferation of basal

Signs (Fig. 4.4)

layers of conjunctival epithelium and increase in

Conjunctival congestion, which is more marked

the number of mucin secreting goblet cells.

in palpebral conjunctiva, fornices and peripheral

4. Conjunctival discharge. It consists of tears,

part of bulbar conjunctiva, giving the appearance

mucus, inflammatory cells, desquamated epithelial

of ‘fiery red eye’. The congestion is typically less

cells, fibrin and bacteria. If the inflammation is

marked in circumcorneal zone.

very severe, diapedesis of red blood cells may

Chemosis i.e., swelling of conjunctiva.

occur and discharge may become blood stained.

Petechial haemorrhages are seen when the

Severity of pathological changes varies depending

causative organism is pneumococcus.

upon the severity of inflammation and the causative

organism. The changes are thus more marked in

purulent conjunctivitis than mucopurulent

conjunctivitis.

CLINICAL TYPES OF BACTERIAL

CONJUNCTIVITIS

Depending upon the causative bacteria and the

severity of infection, bacterial conjunctivitis may

present in following clinical forms:

Acute catarrhal or mucopurulent conjunctivitis.

Acute purulent conjunctivitis

Acute membranous conjunctivitis

Acute pseudomembranous conjunctivitis

Chronic bacterial conjunctivitis

Chronic angular conjunctivitis

Fig. 4.4. Signs of acute mucopurulent conjunctivitis.

ACUTE MUCOPURULENT CONJUNCTIVITIS

Acute mucopurulent conjunctivitis is the most

Flakes of mucopus are seen in the fornices,

common type of acute bacterial conjunctivitis. It is

canthi and lid margins.

characterised by marked conjunctival hyperaemia and

Cilia are usually matted together with yellow

mucopurulent discharge from the eye.

crusts.

Common causative bacteria are: Staphylococcus

Clinical course. Mucopurulent conjunctivitis

aureus, Koch-Weeks bacillus, Pneumococcus and

reaches its height in three to four days. If untreated,

Streptococcus. Mucopurulent conjunctivitis

in mild cases the infection may be overcome and the

generally accompanies exanthemata such as measles

condition is cured in 10-15 days; or it may pass to

and scarlet fever.

less intense form, the

‘chronic catarrhal

conjunctivitis’.

Clinical picture

Complications. Occasionally the disease may be

Symptoms

complicated by marginal corneal ulcer, superficial

Discomfort and foreign body sensation due to

keratitis, blepharitis or dacryocystitis.

engorgement of vessels.

Mild photophobia, i.e., difficulty to tolerate light.

Differential diagnosis

Mucopurulent discharge from the eyes.

1. From other causes of acute red eye (see page

Sticking together of lid margins with discharge

147).

during sleep.

2. From other types of conjunctivitis. It is made out

Slight blurring of vision due to mucous flakes in

from the typical clinical picture of disease and is

front of cornea.

confirmed by conjunctival cytology and

Sometimes patient may complain of coloured

bacteriological examination of secretions and

halos due to prismatic effect of mucus present on

scrapings (Table 4.1).

cornea.

DISEASES OF THE CONJUNCTIVA

Table 4.1. Differentiating features of common types of conjunctivitis

Bacterial

Viral

Allergic

Chlamydial (TRIC)

[A]

CLINICAL SIGNS

1. Congestion

Marked

Moderate

Mild to moderate

Moderate

2. Chemosis

3. Subconjunctival

haemorrhages

4. Discharge

Purulent or

Watery

Ropy/

Mucopurulent

mucopurulent

watery

5. Papillae

6. Follicles

7. Pseudomembrane

8. Pannus

- (Except vernal)

9. Pre-auricular

lymph nodes

[B]

CYTOLOGICAL FEATURES

1. Neutrophils

(Early)

2. Eosinophils

3. Lymphocytes

4. Plasma cells

5. Multinuclear cells

6. Inclusion bodies :

Cytoplasmic

+ (Pox)

Nuclear

+ (Herpes)

7. Micro-organisms

Treatment

advocated earlier) is however contraindicated as

1. Topical antibiotics to control the infection

it will wash away the lysozyme and other

constitute the main treatment of acute

protective proteins present in tears.

mucopurulent conjunctivitis. Ideally, the antibiotic

3. Dark goggles may be used to prevent photo-

should be selected after culture and sensitivity

phobia.

tests but in practice, it is difficult. However, in

4. No bandage should be applied in patients with

routine, most of the patients respond well to

mucopurulent conjunctivitis. Exposure to air keeps

broad specturm antibiotics. Therefore, treatment

the temperature of conjunctival cul-de-sac low

may be started with chloramphenicol

(1%),

which inhibits the bacterial growth; while after

gentamycin (0.3%) or framycetin eye drops 3-4

bandaging, conjunctival sac is converted into an

hourly in day and ointment used at night will not

incubator, and thus infection flares to a severe

only provide antibiotic cover but also help to

degree within 24 hours. Further, bandaging of

reduce the early morning stickiness. If the patient

eye will also prevent the escape of discharge.

does not respond to these antibiotics, then the

5. No steroids should be applied, otherwise infection

newer antibiotic drops such as ciprofloxacin

will flare up and bacterial corneal ulcer may

(0.3%), ofloxacin (0.3%) or gatifloxacin (0.3%)

develop.

may be used.

6. Anti-inflammatory and analgesic drugs

(e.g.

2. Irrigation of conjunctival sac with sterile warm

ibuprofen and paracetamol) may be given orally

saline once or twice a day will help by removing

for 2-3 days to provide symptomatic relief from

the deleterious material. Frequent eyewash (as

mild pain especially in sensitive patients.

Comprehensive OPHTHALMOLOGY

ACUTE PURULENT CONJUNCTIVITIS

3. Stage of slow healing. During this stage, pain is

decreased and swelling of the lids subsides.

Acute purulent conjunctivitis also known as acute

Conjunctiva remains red, thickened and velvety.

blenorrhea or hyperacute conjunctivitis is

Discharge diminishes slowly and in the end

characterised by a violent inflammatory response. It

resolution is complete.

occurs in two forms: (1) Adult purulent conjunctivitis

Associations. Gonococcal conjunctivitis is usually

and (2) Ophthalmia neonatorum in newborn (see

associated with urethritis and arthritis.

page 71).

Complications

ACUTE PURULENT CONJUNCTIVITIS

1. Corneal involvement is quite frequent as the

OF ADULTS

gonococcus can invade the normal cornea through

Etiology

an intact epithelium. It may occur in the form of

diffuse haze and oedema, central necrosis, corneal

The disease affects adults, predominantly males.

ulceration or even perforation.

Commonest causative organism is Gonococcus; but

2. Iridocyclitis may also occur, but is not as

rarely it may be Staphylococcus aureus or

common as corneal involvement.

Pneumococcus. Gonococcal infection directly

3. Systemic complications, though rare, include

spreads from genitals to eye. Presently incidence of

gonorrhoea arthritis, endocarditis and septicaemia.

gonococcal conjunctivitis has markedly decreased.

Treatment

Clinical picture

Systemic therapy is far more critical than the

It can be divided into three stages:

topical therapy for the infections caused by N.

Stage of infiltraton. It lasts for 4-5 days and is

gonorrhoeae and N. meningitidis. Because of

characterised by:

the resistant strains penicillin and tetracyline are

Considerably painful and tender eyeball.

no longer adequate as first-line treatment. Any of

Bright red velvety chemosed conjunctiva.

the following regimes can be adopted :

Lids are tense and swollen.

Norfloxacin 1.2 gm orally qid for 5 days

Discharge is watery or sanguinous.

Cefoxitim 1.0 gm or cefotaxime 500 mg. IV qid

Pre-auricular lymph nodes are enlarged.

or ceftriaxone 1.0 gm IM qid, all for 5 days; or

Stage of blenorrhoea. It starts at about fifth day,

Spectinomycin 2.0 gm IM for 3 days.

lasts for several days and is characterised by:

All of the above regimes should then be followed

Frankly purulent, copious, thick discharge

by a one week course of either doxycycline 100

trickling down the cheeks (Fig. 4.5).

mg bid or erythromycin 250-500 mg orally qid.

Other symptoms are increased but tension in

Topical antibiotic therapy presently

the lids is decreased.

recommended includes ofloxacin, ciprofloxacin or

tobramycin eye drops or bacitracin or

erythromycin eye ointment every 2 hours for the

first 2-3 days and then 5 times daily for 7 days.

Because of the resistant strains, intensive therapy

with penicillin drops is not reliable.

Irrigation of the eyes frequently with sterile

saline is very therapeutic in washing away

infected debris.

Other general measures are similar to acute

mucopurulent conjunctivitis.

Topical atropine 1 per cent eye drops should be

instilled once or twice a day if cornea is involved.

Patient and the sexual partner should be referred

for evaluation of other sexually transmitted dis-

Fig. 4.5. Acute purulent conjunctivitis.

eases.

DISEASES OF THE CONJUNCTIVA

ACUTE MEMBRANOUS CONJUNCTIVITIS

It is an acute inflammation of the conjunctiva,

characterized by formation of a true membrane on the

conjunctiva. Now-a-days it is of very-very rare

occurrence, because of markedly decreased

incidence of diphtheria. It is because of the fact that

immunization against diptheria is very effective.

Etiology

The disease is typically caused by Corynebacterium

diphtheriae and occasionally by virulent type of

Streptococcus haemolyticus.

Pathology

Fig. 4.6. Acute membranous conjunctivitis.

Corynebacterium diphtheriae produces a violent

inflammation of the conjunctiva, associated with

Complications

deposition of fibrinous exudate on the surface as well

1. Corneal ulceration is a frequent complication in

as in the substance of the conjunctiva resulting in

acute stage. The bacteria may even involve the

formation of a membrane. Usually membrane is formed

intact corneal epithelium.

in the palpebral conjunctiva. There is associated

2. Delayed complications due to cicatrization include

coagulative necrosis, resulting in sloughing of

symblepharon, trichiasis, entropion and

membrane. Ultimately healing takes place by

conjunctival xerosis.

granulation tissue.

Diagnosis

Clinical features

Diagnosis is made from typical clinical features and

The disease usually affects children between 2-8

confirmed by bacteriological examination.

years of age who are not immunised against

diphtheria. The disease may have a mild or very severe

Treatment

course. The child is toxic and febrile. The clinical

A. Topical therapy

picture of the disease can be divided into three stages:

1. Penicillin eye drops (1:10000 units per ml) should

1. Stage of infiltration is characterised by:

be instilled every half hourly.

Scanty conjunctival discharge and severe pain

2. Antidiphtheric serum (ADS) should be instilled

in the eye.

every one hour.

Lids are swollen and hard.

3. Atropine sulfate 1 percent ointment should be

Conjunctiva is red, swollen and covered with

added if cornea is ulcerated.

a thick grey-yellow membrane (Fig. 4.6). The

membrane is tough and firmly adherent to the

4. Broad spectrum antibiotic ointment should be

conjunctiva, which on removing bleeds and

applied at bed time.

leaves behind a raw area.

B. Systemic therapy

Pre-auricular lymph nodes are enlarged.

1. Crystalline penicillin

5 lac units should be

2. Stage of suppuration. In this stage, pain

injected intramuscularly twice a day for 10 days.

decreases and the lids become soft. The

2. Antidiphtheric serum (ADS) (50 thousand units)

membrane is sloughed off leaving a raw surface.

should be given intramuscularly stat.

There is copious outpouring of purulent

C. Prevention of symblepharon

discharge.

3. Stage of cicatrisation. In this stage, the raw

Once the membrane is sloughed off, the healing of

surface covered with granulation tissue is

raw surfaces will result in symblepharon, which should

epithelised. Healing occurs by cicatrisation, which

be prevented by applying contact shell or sweeping

may cause trichiasis and conjunctival xerosis.

the fornices with a glass rod smeared with ointment.

Comprehensive OPHTHALMOLOGY

Prophylaxis

Clinical picture

1. Isolation of patient will prevent family members

Pseudomembranous conjunctivitis is characterized

from being infected.

by:

2. Proper immunization against diphtheria is very

Acute mucopurulent conjunctivitis, like features

effective and provides protection to the

(see page 56) associated with.

community.

Pseudomembrane formation which is thin

yellowish-white membrane seen in the fornices

PSEUDOMEMBRANOUS CONJUNCTIVITIS

and on the palpebral conjunctiva

(Fig.

4.7).

It is a type of acute conjunctivitis, characterised by

Pseudomembrane can be peeled off easily and

formation of a pseudomembrane (which can be easily

does not bleed.

peeled off leaving behind intact conjunctival

epithelium) on the conjunctiva.

Treatment

It is similar to that of mucopurulent conjunctivitis.

Etiology

It may be caused by following varied factors:

CHRONIC CATARRHAL CONJUNCTIVITIS

1. Bacterial infection. Common causative organisms

‘Chronic catarrhal conjunctivitis’ also known as

are Corynebacterium diphtheriae of low virulence,

‘simple chronic conjunctivitis’ is characterised by

staphylococci, streptococci, H. influenzae and N.

mild catarrhal inflammation of the conjunctiva.

gonorrhoea.

2. Viral infections such as herpes simplex and

Etiology

adenoviral epidemic keratoconjunctivitis may also

be sometimes associated with pseudomembrane

A. Predisposing factors

formation.

1. Chronic exposure to dust, smoke, and chemical

3. Chemical irritants such as acids, ammonia, lime,

irritants.

silver nitrate and copper sulfate are also known

2. Local cause of irritation such as trichiasis,

to cause formation of such membrane.

concretions, foreign body and seborrhoeic scales.

Pathology

3. Eye strain due to refractive errors, phorias or

convergence insufficiency.

The above agents produce inflammation of conju-

nctiva associated with pouring of fibrinous exudate

4. Abuse of alcohol, insomnia and metabolic

on its surface which coagulates and leads to formation

disorders.

of a pseudomembrane.

B. Causative organisms

Staphylococcus aureus is the commonest cause

of chronic bacterial conjunctivitis.

Gram negative rods such as Proteus mirabilis,

Klebsiella pneumoniae, Escherichia coli and

Moraxella lacunata are other rare causes.

C. Source and mode of infection. Chronic

conjunctivitis may occur:

1. As continuation of acute mucopurulent

conjunctivitis when untreated or partially treated.

2. As chronic infection from associated chronic

dacryocystitis, chronic rhinitis or chronic upper

respiratory catarrh.

3. As a mild exogenous infection which results from

direct contact, air-borne or material transfer of

Fig. 4.7. Pseudomembranous conjunctivitis.

infection.

DISEASES OF THE CONJUNCTIVA

Clinical picture

Pathology

Symptoms of simple chronic conjunctivitis include:

The causative organism, i.e., MA bacillus produces a

Burning and grittiness in the eyes, especially in

proteolytic enzyme which acts by macerating the

the evening.

epithelium. This proteolytic enzyme collects at the

Mild chronic redness in the eyes.

angles by the action of tears and thus macerates the

Feeling of heat and dryness on the lid margins.

epithelium of the conjunctiva, lid margin and the skin

the surrounding angles of eye. The maceration is

Difficulty in keeping the eyes open.

followed by vascular and cellular responses in the

Mild mucoid discharge especially in the canthi.

form of mild grade chronic inflammation. Skin may

Off and on lacrimation.

show eczematous changes.

Feeling of sleepiness and tiredness in the eyes.

Clinical picture

Signs. Grossly the eyes look normal but careful

examination may reveal following signs:

Symptoms

Congestion of posterior conjunctival vessels.

Irritation, smarting sensation and feeling of

Mild papillary hypertrophy of the palpebral

discomfort in the eyes.

conjunctiva.

History of collection of dirty-white foamy

Surface of the conjunctiva looks sticky.

discharge at the angles.

Lid margins may be congested.

Redness in the angles of eyes.

Signs (Fig. 4.8) include:

Treatment

Hyperaemia of bulbar conjunctiva near the canthi.

1. Predisposing factors when associated should be

Hyperaemia of lid margins near the angles.

treated and eliminated.

Excoriation of the skin around the angles.

2. Topical antibiotics such as chloramphenicol or

Presence of foamy mucopurulent discharge at the

gentamycin should be instilled 3-4 times a day for

angles.

about

2 weeks to eliminate the mild chronic

Complications include: blepharitis and shallow

infection.

marginal catarrhal corneal ulceration.

3. Astringent eye drops such as zinc-boric acid

drops provide symptomatic relief.

ANGULAR CONJUNCTIVITIS

It is a type of chronic conjunctivitis characterised by

mild grade inflammation confined to the conjunctiva

and lid margins near the angles (hence the name)

associated with maceration of the surrounding skin.

Etiology

1. Predisposing factors are same as for 'simple

chronic conjunctivitis'.

2. Causative organisms. Moraxella Axenfeld is the

commonest causative organism. MA bacilli are

placed end to end, so the disease is also called

'diplobacillary conjunctivitis'. Rarely, staphylo-

cocci may also cause angular conjunctivitis.

3. Source of infection is usually nasal cavity.

4. Mode of infection. Infection is transmitted from

nasal cavity to the eyes by contaminated fingers

Fig. 4.8. Signs of angular conjunctivitis.

or handkerchief.

Comprehensive OPHTHALMOLOGY

Treatment

Class 1 : Blinding trachoma. Blinding trachoma refers

A.Prophylaxis includes treatment of associated

to hyperendemic trachoma caused by serotypes A,

nasal infection and good personal hygiene.

B, Ba and C of Chlamydia trachomatis associated with

B. Curative treatment consists of :

secondary bacterial infection. It is transmitted from

1. Oxytetracycline (1%) eye ointment 2-3 times a

eye to eye by transfer of ocular discharge through

day for 9-14 days will eradicate the infection.

various modes.

2. Zinc lotion instilled in day time and zinc oxide

Class 2 : Non-blinding trachoma. It is also caused

ointment at bed time inhibits the proteolytic

by Chlamydia trachomatis serotypes A, B, Ba, and C;

ferment and thus helps in reducing the

but is usually not associated with secondary bacterial

maceration.

infections. It occurs in mesoendemic or hypoendemic

areas with better socioeconomic conditions. It is a

CHLAMYDIAL CONJUNCTIVITIS

mild form of disease with limited transmission owing

Chlamydia lie midway between bacteria and viruses,

to improved hygiene.

sharing some of the properties of both. Like viruses,

Class 3: Paratrachoma. It refers to oculogenital

they are obligate intracellular and filterable, whereas

chlamydial disease caused by serotypes D to K of

like bacteria they contain both DNA and RNA, divide

chlamydia trachomatis. It spreads from genitals to

by binary fission and are sensitive to antibiotics.

eye and mostly seen in urban population. It manifests

The chlamydia combinedly form the PLT group

as either adult inclusion conjunctivitis or chlamydial

(Psittacosis, Lymphogranuloma venereum and

ophthalmia neonatorum.

Trachomatis group).

Life cycle of the chlamydia. The infective particle

TRACHOMA

invades the cytoplasm of epithelial cells, where it

Trachoma

(previously known as Egyptian

swells up and forms the 'initial body'. The initial

ophthalmia) is a chronic keratoconjunctivitis,

bodies rapidly divide into 'elementary bodies'

primarily affecting the superficial epithelium of

embedded in glycogen matrix which are liberated when

conjunctiva and cornea simultaneously. It is

the cells burst. Then the 'elementary bodies' infect

characterised by a mixed follicular and papillary

other cells where the whole cycle is repeated.

response of conjunctival tissue. It is still one of the

Ocular infections produced by chlamydia in human

leading causes of preventable blindness in the world.

beings are summarised in Table 4.2.

The word 'trachoma' comes from the Greek word for

Jones' classification. Jones' has classified chlamydial

'rough' which describes the surface appearance of

infections of the eye into following three classes :

the conjunctiva in chronic trachoma.

Table 4.2. Summary of ocular infections caused by chlamydia

Genus

Chlamydia

Species

C. trachomatis

C. lymphogranulomatis

C. psittacosis

(TRIC agent) (Humans)

(Humans)

(Animals)

Serotype

A, B, Ba, C

D to K

L1, L2, L3

Ocular

Hyperendemic Paratrachoma

Lymphogranuloma

disease

trachoma

(- neonatal

venereum

and adult inclusion

conjunctivitis

conjunctivitis)

Transmission

Eye to eye

Genitals to eye

DISEASES OF THE CONJUNCTIVA

Etiology

D. Modes of infection. Infection may spread from

A. Causative organism. Trachoma is caused by a

eye to eye by any of the following modes:

Bedsonian organism, the Chlamydia trachomatis

1. Direct spread of infection may occur through

belonging to the Psittacosis-lymphogranuloma-

contact by air-borne or water-borne modes.

trachoma (PLT) group. The organism is epitheliotropic

2. Vector transmission of trachoma is common

and produces intracytoplasmic inclusion bodies

through flies.

called H.P. bodies (Halberstaedter Prowazeke

3. Material transfer plays an important role in the

bodies). Presently, 11 serotypes of chlamydia, (A, B,

spread of trachoma. Material transfer can occur

Ba, C, D, E, F, G, H, J and K) have been identified

through contaminated fingers of doctors, nurses

using microimmunofluorescence techniques.

and contaminated tonometers. Other sources of

Serotypes A, B, Ba and C are associated with

material transfer of infection are use of common

hyperendemic (blinding) trachoma, while serotypes

towel, handkerchief, bedding and surma-rods.

D-K are associated with paratrachoma (oculogenital

chlamydial disease).

Prevalence

B. Predisposing factors. These include age, sex, race,

Trachoma is a worldwide disease but it is highly

climate, socioeconomic status and environmental

prevalent in North Africa, Middle East and certain

factors.

regions of Sourth-East Asia. It is believed to affect

1. Age. The infection is usually contracted during

some 500 million people in the world. There are about

infancy and early childhood. Otherwise, there is

150 million cases with active trachoma and about 30

no age bar.

million having trichiasis, needing lid surgery.

2. Sex. As far as sex is concerned, there is general

Trachoma is responsible for 15-20 percent of the

agreement that preponderance exists in the

world's blindness, being second only to cataract.

females both in number and in severity of disease.

Clinical profile of trachoma

3. Race. No race is immune to trachoma, but the

disease is very common in Jews and comparatively

Incubation period of trachoma varies from 5-21 days.

less common among Negroes.

Onset of disease is usually insidious (subacute),

however, rarely it may present in acute form.

4. Climate. Trachoma is more common in areas with

dry and dusty weather.

Clinical course of trachoma is determined by the

5. Socioeconomic status. The disease is more

presence or absence of secondary infection. In the

common in poor classes owing to unhygienic

absence of such an infection, a pure trachoma is so

living conditions, overcrowding, unsanitary

mild and symptomless that the disease is usually

conditions, abundant fly population, paucity of

neglected. But, mostly the picture is complicated by

water, lack of materials like separate towels and

secondary infection and may start with typical

handkerchiefs, and lack of education and

symptoms of acute conjunctivitis. In the early

understanding about spread of contagious

stages it is clinically indistinguishable from the

diseases.

bacterial conjunctivitis and the term 'trachoma-

6. Environmental factors like exposure to dust,

dubium' (doubtful trachoma) is sometimes used for

smoke, irritants, sunlight etc. increase the risk of

this stage.

contracting disease. Therefore, outdoor workers

Natural history. In an endemic area natural history

are more affected in comparison to office workers.

of trachoma is characterized by the development of

C. Source of infection. In trachoma endemic zones

acute disease in the first decade of life which

the main source of infection is the conjunctival

continues with slow progression, until the disease

discharge of the affected person. Therefore,

becomes inactive in the second decade of life. The

superimposed bacterial infections help in

sequelae occur at least after 20 years of the disease.

transmission of the disease by increasing the

Thus, the peak incidence of blinding sequelae is seen

conjunctival secretions.

in the fourth and fifth decade of life.

Comprehensive OPHTHALMOLOGY

Symptoms

In the absence of secondary infection, symptoms

are minimal and include mild foreign body

sensation in the eyes, occasional lacrimation,

slight stickiness of the lids and scanty mucoid

discharge.

In the presence of secondary infection, typical

symptoms of acute mucopurulent conjunctivitis

develop.

Signs

A. Conjunctival signs

1. Congestion of upper tarsal and forniceal

Fig. 4.10. Trachomatous inflammation follicular (TF)

conjunctiva.

2. Conjunctival follicles. Follicles

(Fig.

4.9 and

follicular conjunctivitis.

Fig.4.10) look like boiled sagograins and are

3. Papillary hyperplasia. Papillae are reddish, flat

commonly seen on upper tarsal conjunctiva and

topped raised areas which give red and velvety

fornix; but may also be present in the lower

appearance to the tarsal conjunctiva (Fig. 4.11).

fornix, plica semilunaris and caruncle. Sometimes,

Each papilla consists of central core of numerous

(follicles may be seen on the bulbar conjunctiva

dilated blood vessels surrounded by lymphocytes

and covered by hypertrophic epithelium.

(pathognomic of trachoma).

Fig. 4.9. Signs of active traochoma (diagramatic).

Structure of follicle. Follicles are formed due to

scattered aggregation of lymphocytes and other

cells in the adenoid layer. Central part of each follicle

is made up of mononuclear histiocytes, few

Fig. 4.11. Trachomatous inflammation intense (TI)

lymphocytes and large multinucleated cells called

Leber cells. The cortical part is made up of a zone

4. Conjunctival scarring (Fig. 4.12), which may be

of lymphocytes showing active proliferation. Blood

irregular, star-shaped or linear. Linear scar present

vessels are present in the most peripheral part. In

in the sulcus subtarsalis is called Arlt's line.

later stages signs of necrosis are also seen. Presence

5. Concretions may be formed due to accumulation

of Leber cells and signs of necrosis differentiate

of dead epithelial cells and inspissated mucus in

trachoma follicles from follicles of other forms of

the depressions called glands of Henle.

DISEASES OF THE CONJUNCTIVA

3. Pannus i.e., infiltration of the cornea associated

with vascularization is seen in upper part (Fig.

4.13). The vessels are superficial and lie between

epithelium and Bowman's membrane. Later on

Bowman's membrane is also destroyed. Pannus

may be progressive or regressive.

In progressive pannus, infiltration of cornea is

ahead of vascularization.

In regressive pannus (pannus siccus) vessels

extend a short distance beyond the area of

infiltration.

4. Corneal ulcer may sometime develop at the

advancing edge of pannus. Such ulcers are usually

Fig. 4.12. Trachomatous scarring (TS)

shallow which may become chronic and indolent.

5. Herbert pits are the oval or circular pitted

scars, left after healing of Herbert follicles in the

limbal area (Fig. 4.14).

6. Corneal opacity may be present in the upper

part. It may even extend down and involve the

pupillary area. It is the end result of trachomatous

corneal lesions.

Fig. 4.14. Trachomatous Herbert's pits.

Grading of trachoma

McCallan's classification

Fig. 4.13. Trachomatous pannus : (A) progressive,

McCallan in 1908, divided the clinical course of the

(B) regressive (diagramatic) and (C) clinical photograph

trachoma into following four stages:

Stage I (Incipient trachoma or stage of infiltration).

B. Corneal signs

It is characterized by hyperaemia of palpebral

1. Superficial keratitis may be present in the upper

conjunctiva and immature follicles.

part.

Stage II (Established trachoma or stage of florid

2. Herbert follicles refer to typical follicles present

infiltration). It is characterized by appearance of

in the limbal area. These are histologically similar

mature follicles, papillae and progressive corneal

to conjunctival follicles.

pannus.

Comprehensive OPHTHALMOLOGY

Stage III

(Cicatrising trachoma or stage of

scarring). It includes obvious scarring of palpebral

conjunctiva.

Stage IV (Healed trachoma or stage of sequelae).

The disease is quite and cured but sequelae due

to cicatrisation give rise to symptoms.

WHO classification

Trachoma has always been an important blinding

disease under consideration of WHO and thus many

attempts have been made to streamline its clinical

profile. The latest classification suggested by WHO

in 1987 (to replace all the previous ones) is as follows

(FISTO):

Fig. 4.15. Trachomatous trichiasis (TT).

TF: Trachomatous inflammation-follicular. It is

the stage of active trachoma with predominantly

2. Conjunctival sequelae include concretions,

follicular inflammation. To diagnose this stage at

pseudocyst, xerosis and symblepharon.

least five or more follicles (each 0.5 mm or more

3. Corneal sequelae may be corneal opacity, ectasia,

in diameter) must be present on the upper tarsal

corneal xerosis and total corneal pannus (blinding

conjunctiva (Fig. 4.10). Further, the deep tarsal

sequelae).

vessels should be visible through the follicles

4. Other sequelae may be chronic dacryocystitis,

and papillae.

and chronic dacryoadenitis.

TI : Trachomatous inflammation intense. This

stage is diagnosed when pronounced

Complications

inflammatory thickening of the upper tarsal

The only complication of trachoma is corneal ulcer

conjunctiva obscures more than half of the normal

which may occur due to rubbing by concretions, or

deep tarsal vessels (Fig. 4.11).

trichiasis with superimposed bacterial infection.

TS: Trachomatous scarring. This stage is

diagnosed by the presence of scarring in the

Diagnosis

tarsal conjunctiva. These scars are easily visible

A. The clinical diagnosis of trachoma is made from

as white, bands or sheets (fibrosis) in the tarsal

its typical signs; at least two sets of signs should be

conjunctiva (Fig. 4.12).

present out of the following:

TT: Trachomatous trichiasis. TT is labelled when

1. Conjunctival follicles and papillae

at least one eyelash rubs the eyeball. Evidence of

2. Pannus progressive or regressive

recent removal of inturned eyelashes should also

3. Epithelial keratitis near superior limbus

be graded as trachomatous trichiasis (Fig. 4.15).

4. Signs of cicatrisation or its sequelae

CO: Corneal opacity. This stage is labelled when

easily visible corneal opacity is present over the

Clinical grading of each case should be done as

pupil. This sign refers to corneal scarring that is

per WHO classfication into TF, TI, TS, TT or CO.

so dense that at least part of pupil margin is

B. Laboratory diagnosis. Advanced laboratory tests

blurred when seen through the opacity. The

are employed for research purposes only. Laboratory

definition is intended to detect corneal opacities

diagnosis of trachoma includes :

that cause significant visual impairment (less than

1. Conjunctival cytology. Giemsa stained smears

6/18).

showing a predominantly polymorphonuclear

Sequelae of trachoma

reaction with presence of plasma cells and Leber

cells is suggestive of trachoma.

1. Sequelae in the lids may be trichiasis (Fig. 4.15),

2. Detection of inclusion bodies in conjunctival

entropion, tylosis (thickening of lid margin), ptosis,

smear may be possible by Giemsa stain, iodine

madarosis and ankyloblepharon.

DISEASES OF THE CONJUNCTIVA

stain or immunofluorescent staining, specially in

given locally or systemically, but topical treatment is

cases with active trachoma.

preferred because:

3. Enzyme-linked immunosorbent assay (ELISA) for

It is cheaper,

chlamydial antigens.

There is no risk of systemic side-effects, and

4. Polymerase chain reaction (PCR) is also useful.

Local antibiotics are also effective against

5. Isolation of chlamydia is possible by yolk-sac

bacterial conjunctivitis which may be associated

with trachoma.

inoculation method and tissue culture technique.

The following topical and systemic therapy

Standard single-passage McCoy cell culture

regimes have been recommended:

requires at least 3 days.

1. Topical therapy regimes. It is best for individual

6. Serotyping of TRIC agents is done by detecting

cases. It consists of 1 percent tetracycline or 1

specific antibodies using microimmuno-

percent erythromycin eye ointment 4 times a day

fluorescence

(micro-IF) method. Direct

for

6 weeks or 20 percent sulfacetamide eye

monoclonal fluorescent antibody microscopy of

drops three times a day along with 1 percent

conjunctival smear is rapid and inexpensive.

tetracycline eye ointment at bed time for 6 weeks.

Differential diagnosis

The continuous treatment for active trachoma

should be followed by an intermittent treatment

1. Trachoma with follicular hypertrophy must be

especially in endemic or hyperendemic area.

differentiated from acute adenoviral follicular

2. Systemic therapy regimes. Tetracycline or

conjunctivitis (epidemic keratoconjunctivitis) as

erythromycin 250 mg orally, four times a day for

follows :

3-4 weeks or doxycycline 100 mg orally twice

Distribution of follicles in trachoma is mainly on

daily for

3-4 weeks or single dose of

1 gm

upper palpebral conjunctiva and fornix, while in

azithromycin has also been reported to be equally

EKC lower palpebral conjunctiva and fornix is

effective in treating trachoma.

predominantly involved.

3. Combined topical and systemic therapy regime.

Associated signs such as papillae and pannus

It is preferred when the ocular infection is severe

are characteristic of trachoma.

(TI) or when there is associated genital infection.

In clinically indistinguishable cases, laboratory

It includes:

(i)

1 per cent tetracycline or

diagnosis of trachoma helps in differentiation.

erythromycin eye ointment 4 times a day for 6

2. Trachoma with predominant papillary

weeks; and (ii) tetracycline or erythromycin 250

hypertrophy needs to be differentiated from palpebral

mg orally 4 times a day for 2 weeks.

form of spring catarrh as follows:

B. Treatment of trachoma sequelae

Papillae are large in size and usually there is

typical cobble-stone arrangement in spring catarrh.

1. Concretions should be removed with a

pH of tears is usually alkaline in spring catarrh,

hypodermic needle.

while in trachoma it is acidic,

2. Trichiasis may be treated by epilation, electrolysis

Discharge is ropy in spring catarrh.

or cryolysis (see page 348).

In trachoma, there may be associated follicles

3. Entropion should be corrected surgically

(see

and pannus.

page 349).

In clinically indistinguishable cases, conjunctival

4. Xerosis should be treated by artificial tears.

cytology and other laboratory tests for trachoma

C. Prophylaxis

usually help in diagnosis.

Since, immunity is very poor and short lived, so

reinfections and recurrences are likely to occur.

Management

Following prophylactic measures may be helpful

Management of trachoma should involve curative as

against reinfection of trachoma.

well as control measures.

1. Hygienic measures. These help a great deal in

A. Treatment of active trachoma

decreasing the transmission of disease, as

Antibiotics for treatment of active trachoma may be

trachoma is closely associated with personal

Comprehensive OPHTHALMOLOGY

hygiene and environmental sanitation. Therefore,

health education on trachoma should be given to

public. The use of common towel, handkerchief,

surma rods etc. should be discouraged. A good

environmental sanitation will reduce the flies. A

good water supply would improve washing habits.

2. Early treatment of conjunctivitis. Every case of

conjunctivitis should be treated as early as

possible to reduce transmission of disease.

3. Blanket antibiotic therapy

(intermittent

treatment). WHO has recommended this regime

to be carried out in endemic areas to minimise the

Fig. 4.16. Signs of acute follicular conjunctivitis.

intensity and severity of disease. The regime is

to apply 1 percent tetracycline eye ointment twice

Clinical course. The disease runs a benign course

daily for 5 days in a month for 6 months.

and often evolves into the chronic follicular

conjunctivitis.

D. Prevention of trachoma blindness

Differential diagnosis must be made from other

See page 447.

causes of acute follicular conjunctivitis.

ADULT INCLUSION CONJUNCTIVITIS

Treatment

It is a type of acute follicular conjunctivitis associated

1. Topical therapy. It consists of tetracycline (1%)

with mucopurulent discharge. It usually affects the

eye ointment 4 times a day for 6 weeks.

sexually active young adults.

2. Systemic therapy is very important, since the

condition is often associated with an

Etiology

asymptomatic venereal infection. Commonly

Inclusion conjunctivitis is caused by serotypes D to

employed antibiotics are:

K of Chlamydia trachomatis. The primary source of

Tetracycline 250 mg four times a day for 3-4

infection is urethritis in males and cervicitis in females.

weeks.

The transmission of infection may occur to eyes

Erythromycin 250 mg four times a day for 3-4

either through contaminated fingers or more

weeks

(only when the tetracycline is

commonly through contaminated water of swimming

contraindicated e.g., in pregnant and lactating

pools

(hence the name swimming pool

females).

conjunctivitis).

Doxycycline 100 mg twice a day for 1-2 weeks

or 200 mg weekly for 3 weeks is an effective

Clinical features

alternative to tetracycline.

Incubation period of the disease is 4-12 days.

Azithromycin 1 gm as a single dose is also

Symptoms are similar to acute mucopurulent

effective.

conjunctivitis and include:

Ocular discomfort, foreign body sensation,

Prophylaxis

Mild photophobia, and

Improvement in personal hygiene and regular

Mucopurulent discharge from the eyes.

chlorination of swimming pool water will definitely

Signs of inclusion conjunctivitis are:

decrease the spread of disease. Patient's sexual

Conjunctival hyperaemia, more marked in fornices.

partner should be examined and treated.

Acute follicular hypertrophy predominantly of

VIRAL CONJUNCTIVITIS

lower palpebral conjunctiva (Fig. 4.16).

Superficial keratitis in upper half of cornea.

Most of the viral infections tend to affect the

Sometimes, superior micropannus may also occur.

epithelium, both of the conjunctiva and cornea, so,

Pre-auricular lymphadenopathy is a usual finding.

the typical viral lesion is a 'keratoconjunctivitis'. In

DISEASES OF THE CONJUNCTIVA

some viral infections, conjunctival involvement is

time when Apollo XI spacecraft was launched, hence

more prominent (e.g., pharyngo-conjunctival fever),

the name 'Apollo conjunctivitis'.

while in others cornea is more involved (e.g., herpes

Incubation period of EHC is very short (1-2

simplex).

days).

Symptoms include pain, redness, watering, mild

Viral infections of conjunctiva include:

photophobia, transient blurring of vision and lid

Adenovirus conjunctivitis

swelling.

Herpes simplex keratoconjunctivitis

Signs of EHC are conjunctival congestion,

Herpes zoster conjunctivitis

chemosis, multiple haemorrhages in bulbar conju-

Pox virus conjunctivitis

nctiva, mild follicular hyperplasia, lid oedema and

Myxovirus conjunctivitis

pre-auricular lymphadenopathy.

Paramyxovirus conjunctivitis

Corneal involvement may occur in the form of

ARBOR virus conjunctivitis

fine epithelial keratitis.

Clinical presentations. Acute viral conjunctivitis may

Treatment. EHC is very infectious and poses major

present in three clinical forms:

potential problems of cross-infection. Therefore,

1. Acute serous conjunctivitis

prophylactic measures are very important. No specific

2. Acute haemorrhagic conjunctivitis

effective curative treatment is known. However, broad

3. Acute follicular conjunctivitis

(see follicular

spectrum antibiotic eye drops may be used to prevent

conjunctivitis).

secondary bacterial infections. Usually the disease

has a self-limiting course of 5-7 days.

ACUTE SEROUS CONJUNCTIVITIS

Etiology. It is typically caused by a mild grade viral

FOLLICULAR CONJUNCTIVITIS

infection which does not give rise to follicular

It is the inflammation of conjunctiva, characterised

response.

by formation of follicles, conjunctival hyperaemia and

Clinical features. Acute serous conjunctivitis is

discharge from the eyes. Follicles are formed due to

characterised by a minimal degree of congestion, a

localised aggregation of lymphocytes in the adenoid

watery discharge and a boggy swelling of the

layer of conjunctiva. Follicles appear as tiny, greyish

conjunctival mucosa.

white translucent, rounded swellings, 1-2 mm in

diameter. Their appearance resembles boiled sago-

Treatment. Usually it is self-limiting and does not

grains.

need any treatment. But to avoid secondary bacterial

infection, broad spectrum antibiotic eye drops may

Types

be used three times a day for about 7 days.

1. Acute follicular conjunctivitis.

ACUTE HAEMORRHAGIC CONJUNCTIVITIS

2. Chronic follicular conjunctivitis.

3. Specific type of conjunctivitis with follicle

It is an acute inflammation of conjunctiva charac-

formation e.g., trachoma (page 62).

terised by multiple conjunctival haemorrhages,

conjunctival hyperaemia and mild follicular

ACUTE FOLLICULAR CONJUNCTIVITIS

hyperplasia.

It is an acute catarrhal conjunctivitis associated with

Etiology. The disease is caused by picornaviruses

marked follicular hyperplasia especially of the lower

(enterovirus type 70) which are RNA viruses of small

fornix and lower palpebral conjunctiva.

(pico) size. The disease is very contagious and is

transmitted by direct hand-to-eye contact.

General clinical features

Clinical picture. The disease has occurred in an

Symptoms are similar to acute catarrhal conjunctivitis

epidemic form in the Far East, Africa and England and

and include: redness, watering, mild mucoid

hence the name 'epidemic haemorrhagic conjunctivitis

discharge, mild photophobia and feeling of discomfort

(EHC)' has been suggested. An epidemic of the

and foreign body sensation.

disease was first recognized in Ghana in 1969 at the

Signs are conjunctival hyperaemia, associated with

Comprehensive OPHTHALMOLOGY

multiple follicles, more prominent in lower lid than

Corticosteroids should not be used during active

the upper lid (Fig. 4.16).

stage.

Etiological types

Pharyngoconjunctival fever (PCF)

Etiologically, acute follicular conjunctivitis is of the

Etiology. It is an adenoviral infection commonly

following types:

associated with subtypes 3 and 7.

Adult inclusion conjunctivitis (see page 68).

Clinical picture. Pharyngoconjunctival fever is

Epidemic keratoconjunctivitis

characterised by an acute follicular conjunctivitis,

Pharyngoconjunctival fever

associated with pharyngitis, fever and preauricular

Newcastle conjunctivitis

lymphadenopathy. The disease primarily affects

Acute herpetic conjunctivitis.

children and appears in epidemic form. Corneal

involvement in the form of superficial punctate

Epidemic Keratoconjunctivitis (EKC)

keratitis is seen only in 30 percent of cases.

It is a type of acute follicular conjunctivitis mostly

associated with superficial punctate keratitis and

Treatment is usually supportive.

usually occurs in epidemics, hence the name EKC.

Newcastle conjunctivitis

Etiology. EKC is mostly caused by adenoviruses

Etiology. It is a rare type of acute follicular

type 8 and 19. The condition is markedly contagious

conjunctivitis caused by Newcastle virus. The

and spreads through contact with contaminated

infection is derived from contact with diseased owls;

fingers, solutions and tonometers.

and thus the condition mainly affects poultry workers.

Clinical picture. Incubation period after infection is

Clinically the condition is similar to

about 8 days and virus is shed from the inflamed eye

pharyngoconjunctival fever.

for 2-3 weeks.

Acute herpetic conjunctivitis

Clinical stages. The condition mainly affects young

Acute herpetic follicular conjunctivitis is always an

adults. Clinical picture can be arbitrarily divided into

accompaniment of the 'primary herpetic infection',

three stages for the purpose of description only.

which mainly occurs in small children and in

The first phase is of acute serous conjunctivitis

adolescents.

which is characterised by non-specific

Etiology. The disease is commonly caused by herpes

conjunctival hyperaemia, mild chemosis and

simplex virus type 1 and spreads by kissing or other

lacrimation.

close personal contacts. HSV type 2 associated with

Soon it is followed by second phase of typical

genital infections, may also involve the eyes in adults

acute follicular conjunctivitis, characterised by

as well as children, though rarely.

formation of follicles which are more marked in

lower lid.

In severe cases, third phase of 'acute pseudo-

membranous conjunctivitis' is recognised due to

formation of a pseudomembrane on the

conjunctival surface (Fig. 4.17).

Corneal involvement in the form of 'superficial

punctate keratitis', which is a distinctive feature

of EKC, becomes apparent after 1 week of the

onset of disease.

Preauricular lymphadenopathy is associated in

almost all cases.

Treatment. It is usually supportive. Antiviral drugs

are ineffective. Recently, promising results are

Fig. 4.17. Pseudomembrane in acute epidemic keratoc-

reported with adenine arabinoside

(Ara-A).

onjunctivitis (EKC)

DISEASES OF THE CONJUNCTIVA

Clinical picture. Acute herpetic follicular

conjunctivitis is usually a unilateral affection with an

incubation period of 3-10 days. It may occur in two

clinical forms the typical and atypical.

In typical form, the follicular conjunctivitis is

usually associated with other lesions of primary

infection such as vesicular lesions of face and

lids.

In atypical form, the follicular conjunctivitis

occurs without lesions of the face, eyelid and the

condition then resembles epidemic keratoconjun-

ctivitis. The condition may evolve through phases

of non-specific hyperaemia, follicular hyperplasia

and pseudomembrane formation.

Fig. 4.18. Benign folliculosis.

Corneal involvement, though rare, is not unco-

mmon in primary herpes. It may be in the form of

contagiosum. This follicular conjunctivitis occurs as

fine or coarse epithelial keratitis or typical dendritic

a response to toxic cellular debris desquamated into

keratitis.

the conjunctival sac from the molluscum contagiosum

Preauricular lymphadenopathy occurs almost

nodules present on the lid margin (the primary lesion).

always.

3. Chemical chronic follicular conjunctivitis. It is

an irritative follicular conjunctival response which

Treatment. Primary herpetic infection is usually self-

occurs after prolonged administration of topical

limiting. The topical antiviral drugs control the

medication. The common topical preparations

infection effectively and prevent recurrences.

associated with chronic follicular conjunctivitis are:

idoxuridine (IDU), eserine, pilocarpine, DFP and

CHRONIC FOLLICULAR CONJUNCTIVITIS

adrenaline.

It is a mild type of chronic catarrhal conjunctivitis

4. Chronic allergic follicular conjunctivitis. A true

associated with follicular hyperplasia, predominantly

allergic response is usually papillary. However, a

involving the lower lid.

follicular response is also noted in patients with

'contact dermoconjunctivitis'.

Etiological types

1. Infective chronic follicular conjunctivitis is

OPHTHALMIA NEONATORUM

essentially a condition of 'benign folliculosis' with a

Ophthalmia neonatorum is the name given to bilateral

superadded mild infection.

inflammation of the conjunctiva occurring in an infant,

Benign folliculosis, also called 'School

less than 30 days old. It is a preventable disease

folliculosis', mainly affects school children. This

usually occurring as a result of carelessness at the

condition usually occurs as a part of generalized

time of birth. As a matter of fact any discharge or

lymphoid hyperplasia of the upper respiratory tract

even watering from the eyes in the first week of life

(enlargement of adenoids and tonsils) seen at this

should arouse suspicion of ophthalmia neonatorum,

age. It may be associated with malnutrition,

as tears are not formed till then.

constitutional disorders and unhygienic conditions.

Etiology

In this condition, follicles are typically arranged in

parallel rows in the lower palpebral conjunctiva

Source and mode of infection

without any associated conjunctival hyperaemia

Infection may occur in three ways: before birth, during

(Fig.4.18).

birth or after birth.

2. Toxic type of chronic follicular conjunctivitis is

1. Before birth infection is very rare through infected

seen in patients suffering from molluscum

liquor amnii in mothers with ruptured membrances.

Comprehensive OPHTHALMOLOGY

2. During birth. It is the most common mode of

infection from the infected birth canal especially

when the child is born with face presentation or

with forceps.

3. After birth. Infection may occur during first bath

of newborn or from soiled clothes or fingers with

infected lochia.

Causative agents

1. Chemical conjunctivitis It is caused by silver

nitrate or antibiotics used for prophylaxis.

2. Gonococcal infection was considered a serious

disease in the past, as it used to be responsible

Fig. 4.19. Ophthalmia neonatorum.

for

50 per cent of blindness in children. But,

recently the decline in the incidence of gonorrhoea

4. Conjunctiva may show hyperaemia and chemosis.

as well as effective methods of prophylaxis and

There might be mild papillary response in neonatal

treatment have almost eliminated it in developed

inclusion conjunctivitis and herpes simplex

countries. However, in many developing countries

ophthalmia neonatorum.

it still continues to be a problem.

5. Corneal involvement, though rare, may occur in

3. Other bacterial infections, responsible for

the form of superficial punctate keratitis especially

ophthalmia neonatorum are Staphylococcus

in herpes simplex ophthalmia neonatorum.

aureus, Streptococcus haemolyticus, and

Complications

Streptococcus pneumoniae.

Untreated cases, especially of gonococcal ophthalmia

4. Neonatal inclusion conjunctivitis caused by

neonatorum, may develop corneal ulceration, which

serotypes D to K of Chlamydia trachomatis is

may perforate rapidly resulting in corneal

the commonest cause of ophthalmia neonatorum

opacification or staphyloma formation.

in developed countries.

5. Herpes simplex ophthalmia neonatorum is a rare

Treatment

condition caused by herpes simplex-II virus.

Prophylactic treatment is always better than curative.

Clinical features

A. Prophylaxis needs antenatal, natal and postnatal

Incubation period

care.

1. Antenatal measures include thorough care of

It varies depending on the type of the causative agent

mother and treatment of genital infections when

as shown below:

suspected.

Causative agent

Incubation period

2. Natal measures are of utmost importance, as

1. Chemical

4-6 hours

mostly infection occurs during childbirth.

2. Gonococcal

2-4 days

Deliveries should be conducted under hygienic

3. Other bacterial

4-5 days

conditions taking all aseptic measures.

4. Neonatal inclusion

The newborn baby's closed lids should be

conjunctivitis

5-14 days

thoroughly cleansed and dried.

5. Herpes simplex

5-7 days

3. Postnatal measures include :

Symptoms and signs (Fig. 4.19)

Use of either 1 percent tetracycline ointment

1. Pain and tenderness in the eyeball.

0.5 percent erythromycin ointment or

2. Conjunctival discharge. It is purulent in

percent silver nitrate solution (Crede's method)

gonococcal ophthalmia neonatorum and mucoid

into the eyes of the babies immediately after

or mucopurulent in other bacterial cases and

birth.

neonatal inclusion conjunctivitis.

Single injection of ceftriaxone 50 mg/kg IM or

3. Lids are usually swollen.

IV (not to exceed 125 mg) should be given to

DISEASES OF THE CONJUNCTIVA

infants born to mothers with untreated

5. Herpes simplex conjunctivitis is usually a self-

gonococcal infection.

limiting disease. However, topical antiviral drugs

control the infection more effectively and may prevent

B. Curative treatment. As a rule, conjunctival

the recurrence.

cytology samples and culture sensitivity swabs

should be taken before starting the treatment.

ALLERGIC CONJUNCTIVITIS

1. Chemical ophthalmia neonatorum is a self-limiting

It is the inflammation of conjunctiva due to allergic or

condition, and does not require any treatment.

hypersensitivity reactions which may be immediate

2. Gonococcal ophthalmia neonatorum needs

(humoral) or delayed (cellular). The conjunctiva is

prompt treatment to prevent complications.

ten times more sensitive than the skin to allergens.

Topical therapy should include :

Saline lavage hourly till the discharge is

Types

eliminated.

1. Simple allergic conjunctivitis

Bacitracin eye ointment 4 times/day. Because

Hay fever conjunctivitis

of resistant strains topical penicillin therapy is

Seasonal allergic conjunctivitis (SAC)

not reliable. However in cases with proved

Perennial allergic conjunctivitis (PAC)

penicillin susceptibility, penicillin drops 5000

2. Vernal keratoconjunctivitis (VKC)

to 10000 units per ml should be instilled every

3. Atopic keratoconjunctivitis (AKC)

minute for half an hour, every five minutes for

4. Giant papillary conjunctivitis (GPC)

next half an hour and then half hourly till the

5. Phlyctenular keratoconjunctivitis (PKC)

infection is controlled.

6. Contact dermoconjunctivitis (CDC)

If cornea is involved then atropine sulphate

ointment should be applied.

SIMPLE ALLERGIC CONJUNCTIVITIS

ii.

Systemic therapy. Neonates with gonococcal

It is a mild, non-specific allergic conjunctivitis

ophthalmia should be treated for 7 days with one

characterized by itching, hyperaemia and mild

of the following regimes:

papillary response. Basically, it is an acute or subacute

Ceftriaxone 75-100 mg/kg/day IV or IM, QID.

urticarial reaction.

Cefotaxime 100-150 mg/kg/day IV or IM, 12

hourly.

Etiology

Ciprofloxacin 10-20 mg/kg/day or Norfloxacin

It is seen in following forms:

10 mg/kg/day.

1. Hay fever conjunctivitis. It is commonly asso-

If the gonococcal isolate is proved to be

ciated with hay fever

(allergic rhinitis). The

susceptible to penicillin, crystalline benzyl

common allergens are pollens, grass and animal

penicillin G 50,000 units to full term, normal

dandruff.

weight babies and 20,000 units to premature or

2. Seasonal allergic conjunctivitis (SAC). SAC is a

low weight babies should be given

response to seasonal allergens such as grass

intramuscularly twice daily for 3 days.

pollens. It is of very common occurrence.

3. Other bacterial ophthalmia neonatorum should

3. Perennial allergic conjunctivitis

(PAC) is a

be treated by broad spectrum antibiotic drops and

response to perennial allergens such as house

ointments for 2 weeks.

dust and mite. It is not so common.

4. Neonatal inclusion conjunctivitis responds well

Pathology

to topical tetracycline 1 per cent or erythromycin 0.5

per cent eye ointment QID for 3 weeks. However,

Pathological features of simple allergic conjunctivitis

systemic erythromycin (125 mg orally, QID for 3 weeks

comprise vascular, cellular and conjunctival

should also be given since the presence of chlamydia

responses.

agents in the conjunctiva implies colonization of

1. Vascular response is characterised by sudden

upper respiratory tract as well. Both parents should

and extreme vasodilation and increased

also be treated with systemic erythromycin.

permeability of vessels leading to exudation.

Comprehensive OPHTHALMOLOGY

2. Cellular response is in the form of conjunctival

thought to be an atopic allergic disorder in many

infiltration and exudation in the discharge of

cases, in which IgE-mediated mechanisms play an

eosinophils, plasma cells and mast cells producing

important role. Such patients may give personal or

histamine and histamine-like substances.

family history of other atopic diseases such as hay

3. Conjunctival response is in the form of boggy

fever, asthma, or eczema and their peripheral blood

swelling of conjunctiva followed by increased

shows eosinophilia and inceased serum IgE levels.

connective tissue formation and mild papillary

Predisposing factors

hyperplasia.

1. Age and sex. 4-20 years; more common in boys

Clinical picture

than girls.

Symptoms include intense itching and burning

2. Season. More common in summer; hence the

sensation in the eyes associated with watery

name spring catarrh looks a misnomer. Recently

discharge and mild photophobia.

it is being labelled as 'Warm weather

Signs.

(a) Hyperaemia and chemosis which give a

conjunctivitis'.

swollen juicy appearance to the conjunctiva. (b)

3. Climate. More prevalent in tropics, less in

Conjunctiva may also show mild papillary reaction.

temperate zones and almost non-existent in cold

climate.

Diagnosis

Pathology

Diagnosis is made from : (1) typical symptoms and

1. Conjunctival epithelium undergoes hyperplasia

signs; (2) normal conjunctival flora; and (3) presence

and sends downward projections into the

of abundant eosinophils in the discharge.

subepithelial tissue.

Treatment

2. Adenoid layer shows marked cellular infiltration

by eosinophils, plasma cells, lymphocytes and

1. Elimination of allergens if possible.

histiocytes.

2. Local palliative measures which provide

3. Fibrous layer shows proliferation which later on

immediate relief include:

undergoes hyaline changes.

i. Vasoconstrictors like adrenaline, ephedrine,

4. Conjunctival vessels also show proliferation,

and naphazoline.

increased permeability and vasodilation.

ii. Sodium cromoglycate drops are very effective

All these pathological changes lead to formation of

in preventing recurrent atopic cases.

multiple papillae in the upper tarsal conjunctiva.

iii. Steroid eye drops should be avoided. However,

these may be prescribed for short duration in

Clinical picture

severe and non-responsive patients.

Symptoms. Spring catarrh is characterised by marked

3. Systemic antihistaminic drugs are useful in acute

burning and itching sensation which is usually

cases with marked itching.

intolerable and accentuated when patient comes in a

4. Desensitization has been tried without much

warm humid atmosphere. Itching is more marked with

rewarding results. However, a trial may be given

palpebral form of disease.

in recurrent cases.

Other associated symptoms include: mild

photophobia, lacrimation, stringy (ropy) discharge

VERNAL KERATOCONJUNCTIVITIS (VKC) OR

and heaviness of lids.

SPRING CATARRH

It is a recurrent, bilateral, interstitial, self-limiting,

Signs of vernal keratoconjunctivitis can be described

allergic inflammation of the conjunctiva having a

in following three clinical forms:

periodic seasonal incidence.

1. Palpebral form. Usually upper tarsal conjunctiva

of both eyes is involved. The typical lesion is

Etiology

characterized by the presence of hard, flat topped,

It is considered a hypersensitivity reaction to some

papillae arranged in a 'cobble-stone' or 'pavement

exogenous allergen, such as grass pollens. VKC is

stone', fashion (Fig. 4.20). In severe cases, papillae

DISEASES OF THE CONJUNCTIVA

may hypertrophy to produce cauliflower like

excrescences of 'giant papillae'. Conjunctival

changes are associated with white ropy discharge.

Fig. 4.21. Bulbar form of vernal keratoconjunctivitis.

Fig. 4.20. Palpebral form of vernal keratoconjunctivitis.

2. Bulbar form. It is characterised by: (i) dusky red

triangular congestion of bulbar conjunctiva in

palpebral area;

(ii) gelatinous thickened

accumulation of tissue around the limbus; and

(iii) presence of discrete whitish raised dots along

the limbus (Tranta's spots) (Fig. 4.21).

3. Mixed form. It shows combined features of both

palpebral and bulbar forms (Fig. 4.22).

Vernal keratopathy. Corneal involvement in VKC may

Fig. 4.22. Artist's diagram of mixed form of vernal

be primary or secondary due to extension of limbal

keratoconjunctivitis.c

lesions. Vernal keratopathy includes following 5 types

of lesions:

1. Punctate epithelial keratitis involving upper

cornea is usually associated with palpebral form

of disease. The lesions always stain with rose

bengal and invariably with fluorescein dye.

2. Ulcerative vernal keratitis

(shield ulceration)

presents as a shallow transverse ulcer in upper

part of cornea. The ulceration results due to

epithelial macroerosions. It is a serious problem

which may be complicated by bacterial keratitis.

3. Vernal corneal plaques result due to coating of

bare areas of epithelial macroerosions with a

layer of altered exudates (Fig. 4.23).

4. Subepithelial scarring occurs in the form of a

ring scar.

5. Pseudogerontoxon is characterised by a classical

‘cupid’s bow’ outline.

Fig. 4.23. Vernal corneal plaque.

Comprehensive OPHTHALMOLOGY

Clinical course of disease is often self-limiting and

Cold compresses and ice packs have soothing

usually burns out spontaneously after 5-10 years.

effects.

Differential diagnosis. Palpebral form of VKC needs

Change of place from hot to cold area is recom-

to be differentiated from trachoma with pre-dominant

mended for recalcitrant cases.

papillary hypertrophy (see page 67).

E. Desensitization has also been tried without much

rewarding results.

Treatment

F. Treatment of vernal keratopathy

A. Local therapy

Punctate epithelial keratitis requires no extra

1. Topical steroids. These are effective in all forms

treatment except that instillation of steroids should

of spring catarrh. However, their use should be

be increased.

minimised, as they frequently cause steroid

A large vernal plaque requires surgical excision

induced glaucoma. Therefore, monitoring of

by superficial keratectomy.

intraocular pressure is very important during

Severe shield ulcer resistant to medical therapy

steroid therapy. Frequent instillation (4 hourly) to

may need surgical treatment in the form of

start with

(2 days) should be followed by

debridment, superficial keratectomy, excimer laser

maintenance therapy for 3-4 times a day for 2

therapeutic kerateotomy as well as amniotic

weeks.

membrane transplantation to enhance re-

Commonly used steroid solutions are of

epithelialization.

fluorometholone medrysone, betamethasone or

dexamethasone. Medrysone and fluorometholone

Atopic keratoconjunctivitis (AKC)

are safest of all these.

It can be thought of as an adult equivalent of vernal

2. Mast cell stabilizers such as sodium cromoglycate

keratoconjunctivitis and is often associated with

(2%) drops 4-5 times a day are quite effective in

atopic dermatitis. Most of the patients are young

controlling VKC, especially atopic cases. It is

atopic adults, with male predominance.

mast cell stabilizer. Azelastine eye drops are also

effective in controlling VKC.

Symptoms include:

3. Topical antihistaminics are also effective.

Itching, soreness, dry sensation.

4. Acetyl cysteine

(0.5%) used topically has

Mucoid discharge.

mucolytic properties and is useful in the treatment

Photophobia or blurred vision.

of early plaque formation.

Signs

5. Topical cyclosporine

(1%) drops have been

Lid margins are chronically inflamed with rounded

recently reported to be effective in severe

posterior borders.

unresponsive cases.

Tarsal conjunctiva has a milky appearance. There

B. Systemic therapy

are very fine papillae, hyperaemia and scarring

1. Oral antihistaminics may provide some relief

with shrinkage.

from itching in severe cases.

Cornea may show punctate epithelial keratitis,

2. Oral steroids for a short duration have been

often more severe in lower half. There may also

recommended for advanced, very severe, non-

occur corneal vascularization, thinning and

responsive cases.

plaques.

C. Treatment of large papillae. Very large (giant)

Clinical course. Like the dermatitis with which it is

papillae can be tackled either by :

associated, AKC has a protracted course with

Supratarsal injection of long acting steroid or

exacerbations and remissions. Like vernal

Cryo application

keratoconjunctivitis it tends to become inactive when

Surgical excision is recommended for extra-

the patient reaches the fifth decade.

ordinarily large papillae.

Associations may be keratoconus and atopic cataract.

D. General measures include :

Treatment is often frustrating.

Dark goggles to prevent photophobia.

Treat facial eczema and lid margin disease.

DISEASES OF THE CONJUNCTIVA

Sodium cromoglycate drops, steroids and tear

of the conjunctival and corneal epithelium to some

supplements may be helpful for conjunctival

endogenous allergens to which they have become

lesions.

sensitized. Phlyctenular conjunctivitis is of worldwide

distribution. However, its incidence is higher in

GIANT PAPILLARY CONJUNCTIVITIS (GPC)

developing countries.

It is the inflammation of conjunctiva with formation

Etiology

of very large sized papillae.

It is believed to be a delayed hypersensitivity (Type

Etiology. It is a localised allergic response to a

IV-cell mediated) response to endogenous microbial

physically rough or deposited surface (contact lens,

proteins.

prosthesis, left out nylon sutures). Probably it is a

sensitivity reaction to components of the plastic

I. Causative allergens

leached out by the action of tears.

1. Tuberculous proteins were considered,

previously, as the most common cause.

Symptoms. Itching, stringy discharge and reduced

2. Staphylococcus proteins are now thought to

wearing time of contact lens or prosthetic shell.

account for most of the cases.

Signs. Papillary hypertrophy (1 mm in diameter) of

3. Other allergens may be proteins of Moraxella

the upper tarsal conjunctiva, similar to that seen in

Axenfeld bacillius and certain parasites (worm

palpebral form of VKC with hyperaemia are the main

infestation).

signs (Fig. 4.24).

II. Predisposing factors

1. Age. Peak age group is 3-15 years.

2. Sex. Incidence is higher in girls than boys.

3. Undernourishment. Disease is more common in

undernourished children.

4. Living conditions. Overcrowded and unhygienic.

5. Season. It occurs in all climates but incidence is

high in spring and summer seasons.

Pathology

1. Stage of nodule formation. In this stage there

occurs exudation and infiltration of leucocytes

into the deeper layers of conjunctiva leading to

a nodule formation. The central cells are polymor-

phonuclear and peripheral cells are lymphocytes.

Fig. 4.24. Giant papillary conjunctivities (GPC).

The neighbouring blood vessels dilate and their

endothelium proliferates.

Treatment

2. Stage of ulceration. Later on necrosis occurs at

1. The offending cause should be removed. After

the apex of the nodule and an ulcer is formed.

discontinuation of contact lens or artificial eye or

Leucocytic infiltration increases with plasma cells

removal of nylon sutures, the papillae resolve

and mast cells.

over a period of one month.

3. Stage of granulation. Eventually floor of the

2. Disodium cromoglycate is known to relieve the

ulcer becomes covered by granulation tissue.

symptoms and enhance the rate of resolution.

4. Stage of healing. Healing occurs usually with

3. Steroids are not of much use in this condition.

minimal scarring.

PHLYCTENULAR KERATOCONJUNCTIVITIS

Clinical picture

Phlyctenular keratoconjunctivitis is a characteristic

Symptoms in simple phlyctenular conjunctivitis are

nodular affection occurring as an allergic response

few, like mild discomfort in the eye, irritation and reflex

Comprehensive OPHTHALMOLOGY

watering. However, usually there is associated

no clear space between the ulcer and the limbus

mucopurulent conjunctivitis due to secondary

and its long axis is frequently perpendicular to

bacterial infection.

limbus. Such an ulcer usually clears up without

Signs. The phlyctenular conjunctivitis can present in

leaving any opacity.

three forms: simple, necrotizing and miliary.

Fascicular ulcer has a prominent parallel leash

1. Simple phylctenular conjunctivitis. It is the most

of blood vessels (Fig. 4.26). This ulcer usually

commonly seen variety. It is characterised by the

remains superficial but leaves behind a band-

presence of a typical pinkish white nodule

shaped superficial opacity after healing.

surrounded by hyperaemia on the bulbar

conjunctiva, usually near the limbus. Most of the

times there is solitary nodule but at times there

may be two nodules (Fig. 4.25). In a few days the

nodule ulcerates at apex which later on gets

epithelised. Rest of the conjunctiva is normal.

2. Necrotizing phlyctenular conjunctivitis is

characterised by the presence of a very large

phlycten with necrosis and ulceration leading to

a severe pustular conjunctivitis.

3. Miliary phlyctenular conjunctivitis is charact-

erised by the presence of multiple phlyctens

which may be arranged haphazardly or in the

form of a ring around the limbus and may even

form a ring ulcer.

Phlyctenular keratitis. Corneal involvement may

occur secondarily from extension of conjunctival

phlycten; or rarely as a primary disease. It may present

Fig. 4.26. Fascicular corneal ulcer.

in two forms: the 'ulcerative phlyctenular keratitis' or

Miliary ulcer. In this form multiple small ulcers

'diffuse infiltrative keratitis'.

are scattered over a portion of or whole of the

A. Ulcerative phlyctenular keratitis may occur in

cornea.

the following three forms:

1. Sacrofulous ulcer is a shallow marginal ulcer

B. Diffuse infiltrative phlyctenular keratitis may

appear in the form of central infiltration of cornea

formed due to breakdown of small limbal phlycten.

It differs from the catarrhal ulcer in that there is

with characteristic rich vascularization from the

periphery, all around the limbus. It may be superficial

or deep.

Clinical course is usually self-limiting and phlycten

disappears in 8-10 days leaving no trace. However,

recurrences are very common.

Differential diagnosis

Phlyctenular conjunctivitis needs to be differentiated

from the episcleritis, scleritis, and conjunctival

foreign body granuloma.

Presence of one or more whitish raised nodules on

the bulbar conjunctiva near the limbus, with

hyperaemia usually of the surrounding conjunctiva,

Fig. 4.25. Phylctenular conjunctivitis.

in a child living in bad hygienic conditions (most of

DISEASES OF THE CONJUNCTIVA

the times) are the diagnostic features of the

known to produce contact dermoconjunctivitis are

phlyctenular conjunctivitis.

atropine, penicillin, neomycin, soframycin and

gentamycin.

Management

Clinical picture

It includes treatment of phlyctenular conjunctivitis

by local therapy, investigations and specific therapy

1. Cutaneous involvement is in the form of weeping

aimed at eliminating the causative allergen and general

eczematous reaction, involving all areas with which

measures to improve the health of the child.

medication comes in contact.

2. Conjunctival response is in the form of

1. Local therapy.

hyperaemia with a generalised papillary response

i. Topical steroids, in the form of eye drops or

affecting the lower fornix and lower palpebral

ointment

(dexamethasone or betamethasone)

conjunctiva more than the upper.

produce dramatic effect in phlyctenular

Diagnosis is made from:

keratoconjunctivitis.

Typical clinical picture.

ii. Antibiotic drops and ointment should be added

Conjunctival cytology shows a lymphocytic

to take care of the associated secondary infection

response with masses of eosinophils.

(mucopurulent conjunctivitis).

Skin test to the causative allergen is positive in

iii. Atropine (1%) eye ointment should be applied

most of the cases.

once daily when cornea is involved.

Treatment consists of:

2. Specific therapy. Attempts must be made to search

1. Discontinuation of the causative medication,

and eradicate the following causative conditions:

2. Topical steroid eye drops to relieve symptoms,

i. Tuberculous infection should be excluded by X-

and

rays chest, Mantoux test, TLC, DLC and ESR. In

3. Application of steroid ointment on the involved

case, a tubercular focus is discovered,

skin.

antitubercular treatment should be started to

GRANULOMATOUS CONJUNCTIVITIS

combat the infection.

Granulomatous conjunctivitis is the term used to

ii. Septic focus, in the form of tonsillitis, adenoiditis,

describe certain specific chronic inflammations of the

or caries teeth, when present should be

conjunctiva, characterised by proliferative lesions

adequately treated by systemic antibotics and

which usually tend to remain localized to one eye and

necessary surgical measures.

are mostly associated with regional lymphadenitis.

iii. Parasitic infestation should be ruled out by

Common granulomatous conjunctival inflamma-

repeated stool examination and when discovered

tions are:

should be adequately treated for complete

Tuberculosis of conjunctiva

eradication.

Sarcoidosis of conjunctiva

3. General measures aimed to improve the health of

Syphilitic conjunctivitis

child are equally important. Attempts should be made

Leprotic conjunctivitis

to provide high protein diet supplemented with

Conjunctivitis in tularaemia

vitamins A, C and D.

Ophthalmia nodosa

CONTACT DERMOCONJUNCTIVITIS

Parinaud's oculoglandular syndrome

It is the name given to a group of conditions

It is an allergic disorder, involving conjunctiva and

characterised by:

skin of lids along with surrounding area of face.

1. Unilateral granulomatous conjunctivitis (nodular

Etiology

elevations surrounded by follicles),

It is in fact a delayed hypersensitivity (type IV)

2. Preauricular lymphadenopathy, and

response to prolonged contact with chemicals and

3. Fever.

drugs. A few common topical ophthalmic medications

Its common causes are tularaemia, cat-scratch

Comprehensive OPHTHALMOLOGY

disease, tuberculosis, syphilis and lymphogranuloma

venereum.

This term (Parinaud's oculoglandular syndrome)

is largely obsolete, since the infecting agents can

now be usually determined.

Ophthalmia nodosa (Caterpillar hair conjunctivitis)

It is a granulomatous inflammation of the conjunctiva

characterized by formation of a nodule on the bulbar

conjunctiva in response to irritation caused by the

retained hair of caterpillar. The disease is, therefore,

common in summers. The condition may be often

mistaken for a tubercular nodule.

Fig. 4.27. Pinguecula.

Histopathological examination reveals hair

surrounded by giant cells and lymphocytes.

PTERYGIUM

Treatment consists of excision biopsy of the nodule.

Pterygium (L. Pterygion = a wing) is a wing-shaped

fold of conjunctiva encroaching upon the cornea from

either side within the interpalpebral fissure.

DEGENERATIVE CONDITIONS

Etiology. Etiology of pterygium is not definitely

known. But the disease is more common in people

PINGUECULA

living in hot climates. Therefore, the most accepted

Pinguecula is an extremely common degenerative

view is that it is a response to prolonged effect of

condition of the conjunctiva. It is characterized by

environmental factors such as exposure to sun

formation of a yellowish white patch on the bulbar

(ultraviolet rays), dry heat, high wind and abundance

conjunctiva near the limbus. This condition is termed

of dust.

pinguecula, because of its resemblance to fat, which

Pathology. Pathologically pterygium is a

means pinguis.

degenerative and hyperplastic condition of

Etiology of pinguecula is not known exactly. It has

conjunctiva. The subconjunctival tissue undergoes

been considered as an age-change, occurring more

elastotic degeneration and proliferates as

commonly in persons exposed to strong sunlight, dust

vascularised granulation tissue under the epithelium,

and wind. It is also considered a precursor of

which ultimately encroaches the cornea. The corneal

pterygium.

epithelium, Bowman's layer and superficial stroma are

Pathology. There is an elastotic degeneration of

destroyed.

collagen fibres of the substantia propria of

Clinical features. Pterygium is more common in

conjunctiva, coupled with deposition of amorphous

elderly males doing outdoor work. It may be unilateral

hyaline material in the substance of conjunctiva.

or bilateral. It presents as a triangular fold of

Clinical features. Pinguecula (Fig. 4.27) is a bilateral,

conjunctiva encroaching the cornea in the area of

usually stationary condition, presenting as yellowish-

palpebral aperture, usually on the nasal side (Fig.4.28),

white triangular patch near the limbus. Apex of the

but may also occur on the temporal side. Deposition of

triangle is away from the cornea. It affects the nasal

iron seen sometimes in corneal epithelium anterior to

side first and then the temporal side. When

advancing head of pterygium is called stocker's line.

conjunctiva is congested, it stands out as an

Parts. A fully developed pterygium consists of three

avascular prominence.

parts (Fig.4.28):

Complications of pinguecula include its

i. Head (apical part present on the cornea),

inflammation, intraepithelial abscess formation and

ii. Neck (limbal part), and

rarely conversion into pterygium.

Treatment. In routine no treatment is required for

iii. Body (scleral part) extending between limbus and

pinguecula. However, if so desired, it may be excised.

the canthus.

DISEASES OF THE CONJUNCTIVA

Table 4.3. Differences between pterygium and

pseudopterygium

Pterygium

Pseudopterygium

1. Etiology Degenerative

Inflammatory

process

2. Age

Usually occurs

Can occur at any

in elderly

age

persons

3. Site

Always situated

Can occur at any

in the palpebral

site

aperture

4. Stages

Either progressive, Always stationary

ssive,

regressive or

stationary

5. Probe

Probe cannot

A probe can be

test

be passed

passed under the

underneath

neck

Fig. 4.28. Pterygium

Treatment. Surgical excision is the only satisfactory

Types. Depending upon the progression it may be

treatment, which may be indicated for: (1) cosmetic

progressive or regressive pterygium.

reasons, (2) continued progression threatening to

Progressive pterygium is thick, fleshy and

encroach onto the pupillary area (once the pterygium

vascular with a few infiltrates in the cornea, in

has encroached pupillary area, wait till it crosses on

front of the head of the pterygium (called cap of

the other side), (3) diplopia due to interference in

pterygium).

ocular movements.

Regressive pterygium is thin, atrophic, attenuated

with very little vascularity. There is no cap.

Recurrence of the pterygium after surgical excision

Ultimately it becomes membranous but never

is the main problem (30-50%). However, it can be

disappears.

reduced by any of the following measures:

Symptoms. Pterygium is an asymptomatic condition

1. Transplantation of pterygium in the lower fornix

in the early stages, except for cosmetic intolerance.

(McReynold's operation) is not performed now.

Visual disturbances occur when it encroaches the

2. Postoperative beta irradiations (not used now).

pupillary area or due to corneal astigmatism induced

3. Postoperative use of antimitotic drugs such as

due to fibrosis in the regressive stage. Occasionally

mitomycin-C or thiotepa.

diplopia may occur due to limitation of ocular

4. Surgical excision with bare sclera.

movements.

5. Surgical excision with free conjunctival graft taken

Complications like cystic degeneration and infection

from the same eye or other eye is presently the

are infrequent. Rarely, neoplastic change to

preferred technique.

epithelioma, fibrosarcoma or malignant melanoma,

may occur.

6. In recurrent recalcitrant pterygium, surgical

Differential diagnosis. Pterygium must be

excision should be coupled with lamellar

differentiated from pseudopterygium. Pseudo-

keratectomy and lamellar keratoplasty.

pterygium is a fold of bulbar conjunctiva attached to

Surgical technique of pterygium excision

the cornea. It is formed due to adhesions of chemosed

1. After topical anaesthesia, eye is cleansed, draped

bulbar conjunctiva to the marginal corneal ulcer. It

and exposed using universal eye speculum.

usually occurs following chemical burns of the eye.

Differences between pterygium and pseudoptery-

2. Head of the pterygium is lifted and dissected off

gium are given in Table 4.3.

the cornea very meticulously (Fig. 4.29A).

Comprehensive OPHTHALMOLOGY

The main mass of pterygium is then separated

from the sclera underneath and the conjunctiva

superficially.

Pterygium tissue is then excised taking care not

to damage the underlying medial rectus muscle

(Fig. 4.29B).

Haemostasis is achieved and the episcleral tissue

exposed is cauterised thoroughly.

Next step differs depending upon the technique

adopted as follows:

i. In simple excision the conjunctiva is sutured

back to cover the sclera (Fig. 4.29C).

ii. In bare sclera technique, some part of

conjunctiva is excised and its edges are

sutured to the underlying episcleral tissue

leaving some bare part of sclera near the

limbus (Fig. 4.29D).

iii. Free conjunctival membrane graft may be

used to cover the bare sclera (Fig. 4.29E).

This procedure is more effective in reducing

recurrence. Free conjunctiva from the same

or opposite eye may be used as a graft.

iv. Limbal conjunctival autograft trans-

plantation (LLAT) to cover the defet after

pterygium excision is the latest and most

effective technique in the management of

pterygium.

CONCRETIONS

Etiology. Concretions are formed due to accumu-

lation of inspissated mucus and dead epithelial cell

debris into the conjunctival depressions called loops

of Henle. They are commonly seen in elderly people

as a degenerative condition and also in patients with

scarring stage of trachoma. The name concretion is a

misnomer, as they are not calcareous deposits.

Clinical features. Concretions are seen on palpebral

conjunctiva, more commonly on upper than the lower.

They may also be seen in lower fornix. These are

yellowish white, hard looking, raised areas, varying

in size from pin point to pin head. Being hard, they

Fig. 4.29. Surgical technique of pterygium excision : A, dis-

may produce foreign body sensations and lacrimation

section of head from the cornea; B, excision of pterygium

by rubbing the corneal surface. Occasionally they

tissue under the conjunctiva; C, direct closure of the con-

may even cause corneal abrasions.

junctiva after undermining; D, bare sclera technique-suturing

Treatment. It consists of their removal with the help

the conjunctiva to the episcleral tissue; E, free conjunctival

graft after excising the pterygium.

of a hypodermic needle under topical anaesthesia.

DISEASES OF THE CONJUNCTIVA

CHEMOSIS OF CONJUNCTIVA

SYMPTOMATIC CONDITIONS OF

Chemosis or oedema of the conjunctiva is of frequent

CONJUNCTIVA

occurrence owing to laxity of the tissue.

Causes. The common causes of chemosis can be

Hyperaemia of conjunctiva

grouped as under:

Chemosis of conjunctiva

1. Local inflammatory conditions. These include

Ecchymosis of conjunctiva

conjunctivitis, corneal ulcers, fulminating

Xerosis of conjunctiva

iridocyclitis, endophthalmitis, panophthalmitis,

Discoloration of conjunctiva

styes, acute meibomitis, orbital cellulitis, acute

dacryoadenitis, acute dacryocystitis, tenonitis and

SIMPLE HYPERAEMIA OF CONJUNCTIVA

so on.

Simple hyperaemia of conjunctiva means congestion

2. Local obstruction to flow of blood and/or lymph.

of the conjunctival vessels without being associated

It may occur in patients with orbital tumours,

with any of the established diseases.

cysts, endocrine exophthalmos, orbital

pseudotumours, cavernous sinus thrombosis,

Etiology. It may be acute and transient, or recurrent

carotico-cavernous fistula, blockage of orbital

and chronic.

lymphatics following orbital surgery, acute

1. Acute transient hyperaemia. It results due to

congestive glaucoma etc.

temporary irritation caused by: (i) Direct irritants

3. Systemic causes. These include severe anaemia

such as a foreign body, misdirected cilia,

and hypoproteinaemia, congestive heart failure,

concretions, dust, chemical fumes, smoke, stormy

nephrotic syndrome, urticaria, and angioneurotic

wind, bright light, extreme cold, extreme heat and

oedema.

simple rubbing of eyes with hands; (ii) Reflex

hyperaemia due to eye strain, from inflammations

Clinical features and management of chemosis

of nasal cavity, lacrimal passages and lids; (iii)

depends largely upon the causative factor.

Hyperaemia associated with systemic febrile

ECCHYMOSIS OF CONJUNCTIVA

conditions;

(iv) Non-specific inflammation of

conjunctiva.

Ecchymosis or subconjunctival haemorrhage is of

2. Recurrent or chronic hyperaemia. It is often

very common occurrence. It may vary in extent from

noticed in chronic smokers, chronic alcoholics,

small petechial haemorrhage to an extensive one

people residing in dusty, ill-ventilated rooms,

spreading under the whole of the bulbar conjunctiva

workers exposed to prolonged heat, in patients

and thus making the white sclera of the eye invisible.

with rosacea and in patients suffering from

The condition though draws the attention of the

insomnia or otherwise having less sleep.

patients immediately as an emergency but is most of

the time trivial.

Clinical features. Patients with simple hyperaemia

usually complain of a feeling of discomfort,

Etiology. Subconjunctival haemorrhage may be

heaviness, grittiness, tiredness and tightness in the

associated with following conditions:

eyes. There may be associated mild lacrimation and

1. Trauma. It is the most common cause of

minimal mucoid discharge. On cursory examination,

subconjunctival haemorrhage. It may be in the

the conjunctiva often looks normal. However,

form of (i) local trauma to the conjunctiva including

eversion of the lids may reveal mild to moderate

that due to surgery and subconjunctival

congestion being more marked in fornices.

injections,

(ii) retrobulbar haemorrhage which

Treatment. It consists of removal of the cause of

almost immediately spreads below the bulbar

hyperaemia. In acute transient hyperaemia the removal

conjunctiva. Mostly, it results from a retrobulbar

of irritants (e.g., misdirected cilia) gives prompt relief.

injection and from trauma involving various walls

Symptomatic relief may be achieved by use of topical

of the orbit.

decongestants (e.g., 1:10000 adrenaline drops) or

2. Inflammations of the conjunctiva. Petechial

astringent drops (e.g., zinc-boric acid drops).

subconjunctival haemorrhages are usually

Comprehensive OPHTHALMOLOGY

associated with acute haemorrhagic conjunctivitis

to local trauma to eyeball, and not visible when it is

caused by picornaviruses, pneumococcal

due to head injury or injury to the orbit. Most of the

conjunctivitis and leptospirosis, icterohaemorr-

time it is absorbed completely within 7 to 21 days.

hagica conjunctivitis.

During absorption colour changes are noted from

3. Sudden venous congestion of head. The

bright red to orange and then yellow. In severe cases,

subconjunctival haemorrhages may occur owing

some pigmentation may be left behind after

to rupture of conjunctival capillaries due to sudden

absorption.

rise in pressure. Common conditions are whooping

Treatment. (i) Treat the cause when discovered. (ii)

cough, epileptic fits, strangulation or compression

Placebo therapy with astringent eye drops. (iii)

of jugular veins and violent compression of thorax

Psychotherapy and assurance to the patient is most

and abdomen as seen in crush injuries.

important part of treatment. (iv) Cold compresses to

4. Spontaneous rupture of fragile capillaries may

check the bleeding in the initial stage and hot

occur in vascular diseases such as arterioscl-

compresses may help in absorption of blood in late

erosis, hypertension and diabetes mellitus.

stages.

5. Local vascular anomalies like telengiectasia,

Xerosis of conjunctiva

varicosities, aneurysm or angiomatous tumour.

Xerosis of the conjunctiva is a symptomatic condition

6. Blood dyscrasias like anaemias, leukaemias and

in which conjunctiva becomes dry and lustreless.

dysproteinaemias.

Normal conjunctiva is kept moist by its own

7. Bleeding disorders like purpura, haemophilia and

secretions, mucin from goblet cells and aqueous

scurvy.

solution from accessory lacrimal glands. Therefore,

8. Acute febrile systemic infections such as malaria,

even if the main lacrimal gland is removed, xerosis

typhoid, diphtheria, meningococcal septicaemia,

does not occur. Depending upon the etiology,

measles and scarlet fever.

conjunctival xerosis can be divided into two groups,

9. Vicarious bleeding associated with menstruation

parenchymatous and epithelial xerosis.

is an extremely rare cause of subconjunctival

haemorrhage.

1. Parenchymatous xerosis. It occurs following

cicatricial disorganization of the conjunctiva due to

Clinical features. Subconjunctival haemorrhage per

local causes which can be in the form of (i) widespread

se is symptomless. However, there may be symptoms

destructive interstitial conjunctivitis as seen in

of associated causative disease. On examination

trachoma, diptheric membranous conjunctivitis,

subconjunctival haemorrhage looks as a flat sheet of

Steven-Johnsons syndrome, pemphigus or

homogeneous bright red colour with well defined

pemphigoid conjunctivitis, thermal, chemical or

limits (Fig. 4.30). In traumatic subconjunctival

radiational burns of conjunctiva, (ii) exposure of

haemorrhage, posterior limit is visible when it is due

conjunctiva to air as seen in marked degree of

proptosis, facial palsy, ectropion, lack of blinking (as

in coma), and lagophthalmos due to symblepharon.

2. Epithelial xerosis. It occurs due to

hypovitaminosis -A. Epithelial xerosis may be seen

in association with night blindness or as a part and

parcel of the xerophthalmia (the term which is applied

to all ocular manifestations of vitamin A deficiency

which range from night blindness to keratomalacia

(see pages 433-436).

Epithelial xerosis typically occurs in children and

is characterized by varying degree of conjunctival

thickening, wrinkling and pigmentatiion.

Treatment. Treatment of conjunctival xerosis

Fig. 4.30. Subconjunctival haemorrhage.

consists of (i) treatment of the cause, and (ii)

DISEASES OF THE CONJUNCTIVA

symptomatic local treatment with artificial tear

blacks. The pigmented spot freely moves

preparations (0.7% methyl cellulose or 0.3%

with the movement of conjunctiva. It has got

hypromellose or polyvinyl alcohol), which should be

no malignant potential and hence no

instilled frequently.

treatment is required.

ii. Subepithelial melanosis. It may occur as an

Discoloration of conjunctiva

isolated anomaly of conjunctiva (congenital

Normal conjunctiva is a thin transparent structure. In

melanosis oculi Fig. 4.31) or in association

the bulbar region, underlying sclera and a fine

with the ipsilateral hyperpigmentation of the

network of episcleral and conjunctival vessels can

face (oculodermal melanosis or Naevus of

be easily visualized. In the palpebral region and

Ota).

fornices, it looks pinkish because of underlying

iii. Pigmented tumours. These can be benign

fibrovascular tissue.

naevi, precancerous melanosis or malignant

Causes. Conjunctiva may show discoloration in

melanoma.

various local and systemic diseases given below:

1. Red discoloration. A bright red homogeneous

discoloration suggests subconjunctival haemorr-

hage (Fig. 4.30).

2. Yellow discoloration. It may occur due to: (i) bile

pigments in jaundice, (ii) blood pigments in malaria

and yellow fever, (iii) conjunctival fat in elderly

and Negro patients.

3. Greyish discoloration. It may occur due to

application of Kajal (surma or soot) and mascara

in females.

4. Brownish grey discoloration. It is typically seen

in argyrosis, following prolonged application of

Fig. 4.31. Conjunctival melanosis.

silver nitrate for treatment of chronic conjunctival

inflammations. The discoloration is most marked

in lower fornix.

CYSTS AND TUMOURS

5. Blue discoloration. It is usually due to ink tattoo

from pens or effects of manganese dust. Blue

CYSTS OF CONJUNCTIVA

discoloration may also be due to pseudopigmen-

The common cystic lesions of the conjunctiva are:

tation as occurs in patients with blue sclera and

1. Congenital cystic lesions. These are of rare

scleromalacia perforans.

occurrence and include congenital corneoscleral

6. Brown pigmentation. Its common causes can be

cyst and cystic form of epibulbar dermoid.

grouped as under:

2. Lymphatic cysts of conjunctiva. These are

(a) Non-melanocytic pigmentation

common and usually occur due to dilatation of

i. Endogenous pigmentation. It is seen in

lymph spaces in the bulbar conjunctiva.

patients with Addison's disease and

Lymphangiectasis is characterized by a row of

ochronosis.

small cysts. Rarely, lymphangioma may occur as

ii. Exogenous pigmentation. It may follow long-

a single multilocular cyst.

term use of adrenaline for glaucoma.

3. Retention cysts. These occur occasionally due to

Argyrosis may also present as dark brown

blockage of ducts of accessory lacrimal glands of

pigmentation.

Krause in chronic inflammatory conditions, viz.,

(b) Melanocytic pigmentation

trachoma and pemphigus. Retention cysts are

i. Conjunctival epithelial melanosis. It

more common in upper fornix.

develops in early childhood, and then remains

4. Epithelial implantation cyst (traumatic cyst). It

stationary. It is found in 90 percent of the

may develop following implantation of

Comprehensive OPHTHALMOLOGY

conjunctival epithelium in the deeper layers, due

melanoma and lentigo maligna (Hutchinson's

to surgical or non-surgical injuries of conjunctiva.

freckle).

5. Epithelial cysts due to downgrowth of epithelium

III. Malignant: primary melanoma

(malignant

are rarely seen in chronic inflammatory or

melanoma).

degenerative conditions, e.g. cystic change in

A. Non-pigmented Tumours

pterygium.

6. Aqueous cyst. It may be due to healing by cystoid

I. Congenital tumours

cicatrix formation, following surgical or non-

1. Dermoids. These are common congenital tumours

surgical perforating limbal wounds.

which usually occur at the limbus. They appear as

7. Pigmented epithelial cyst. It may be formed

solid white masses, firmly fixed to the cornea (Fig.

sometimes following prolonged topical use of

4.33). Dermoid consists of collagenous connective

cocaine or epinephrine.

tissue, sebaceous glands and hair, lined by epidermoid

8. Parasitic cysts such as subconjunctival

epithelium. Treatment is simple excision.

cysticercus (Fig. 4.32), hydatid cyst and filarial

cyst are not infrequent in developing countries.

Fig. 4.32. Cysticercosis of conjunctiva.

Fig. 4.33. Limbal dermoid.

Treatment

2. Lipodermoid (Fig. 4.34). It is a congenital tumour,

Conjunctival cysts need a careful surgical excision.

usually found at the limbus or outer canthus. It

The excised cyst should always be subjected to

appears as soft, yellowish white, movable

histopathological examination.

subconjunctival mass. It consists of fatty tissue and

the surrounding dermis-like connective tissue, hence

TUMOURS OF THE CONJUNCTIVA

the name lipodermoid.

Classification

Sometimes the epibulbar dermoids or lipodermoids

Non-pigmented tumours

may be associated with accessory auricles and other

Congenital: dermoid and lipodermoid

congenital defects (Goldenhar's syndrome).

(choristomas).

II. Benign: simple granuloma, papilloma, adenoma,

II. Benign tumours

fibroma and angiomas.

1. Simple granuloma. It consists of an extensive

III. Premalignant: intraepithelial epithelioma

polypoid, cauliflower-like growth of granulation

(Bowen's disease).

tissue. Simple granulomas are common following

IV. Malignant: epithelioma or squamous cell

squint surgery, as foreign body granuloma and

carcinoma, basal cell carcinoma.

following inadequately scraped chalazion.

Pigmented tumours

Treatment consists of complete surgical removal.

Benign: naevi or congenital moles.

2. Papilloma. It is a benign polypoid tumour usually

II.

Precancerous melanosis: superficial spreading

occurring at inner canthus, fornices or limbus. It may

DISEASES OF THE CONJUNCTIVA

Fig. 4.34. Lipodermoid.

Fig. 4.35. Squamous cell carcinoma at the limbus.

resemble the cocks comb type of conjunctival

B. Pigmented tumours

tubercular lesion. It has a tendency to undergo

1. Naevi or congenital moles. These are common

malignant change and hence needs complete excision.

pigmented lesions, usually presenting as grey

3. Fibroma. It is a rare soft or hard polypoid growth

gelatinous, brown or black, flat or slightly raised

usually occurring in lower fornix.

nodules on the bulbar conjunctiva, mostly near the

limbus (Fig.4.36). They usually appear during early

III. Pre-malignant tumours

childhood and may increase in size at puberty or

Bowen's intraepithelial epithelioma (carcinoma in-

during pregnancy. Histologically, they resemble their

situ). It is a rare, precancerous condition, usually

cutaneous brethren. Malignant change is very rare

occurring at the limbus as a flat, reddish grey,

and when occurs is indicated by sudden increase in

vascularised plaque. Histologically, it is confined

size or increase in pigmentation or appearance of

within the epithelium. It should be treated by complete

signs of inflammation. Therefore, excision is usually

local excision.

indicated for cosmetic reasons and rarely for medical

reasons. Whatever may be the indication, excision

IV. Malignant tumours

should be complete.

1. Squamous cell carcinoma (epithelioma) (Fig. 4.35).

2. Precancerous melanosis. Precancerous melanosis

It usually occurs at the transitional zones i.e. at limbus

(intraepithelial melanoma) of conjunctiva occurs in

and the lid margin. The tumour invades the stroma

adults as 'superficial spreading melanoma'. It never

deeply and may be fixed to underlying tissues.

arises from a congenital naevus.

Histologically, it is similar to squamous cell

carcinomas occurring elsewhere (see page 361).

Treatment. Early cases may be treated by complete

local excision combined with extensive diathermy

cautery of the area. However, in advanced and

recurrent cases radical excision including enucleation

or even exenteration may be needed along with

postoperative radiotherapy.

2. Basal cell carcinoma. It may invade the

conjunctiva from the lids or may arise pari-passu from

the plica semilunaris or caruncle. Though it responds

very favourably to radiotherapy, the complete surgical

excision, if possible, should be preferred to avoid

complications of radio- therapy.

Fig. 4.36. conjunctival naevus.

Comprehensive OPHTHALMOLOGY

Clinically a small pigmented tumour develops at any

occur due to malignant change in pre-existing naevus.

site on the bulbar or palpebral conjunctiva, which

The condition usually occurs in elderly patients.

spreads as a diffuse, flat, asymptomatic pigmented

Clinically it may present as pigmented or non-

patch. As long as it maintains its superficial spread, it

pigmented mass near limbus or on any other part of

does not metastasize. However, ultimately in about

the conjunctiva. It spreads over the surface of the

20 percent cases it involves the subepithelial tissues

globe and rarely penetrates it. Distant metastasis

and proceeds to frank malignant change.

occurs elsewhere in the body, commonly in liver.

Treatment. In early stages local excision with

postoperative radiotherapy may be sufficient. But in

Histologically, the neoplasm may be alveolar, round-

case of recurrence, it should be treated as malignant

celled or spindle-celled.

melanoma.

Treatment. Once suspected, enucleation or

3. Malignant melanoma (primary melanoma).

Malignant melanoma of the conjunctiva mostly arises

exenteration is the treatment of choice, depending

de-novo, usually near the limbus, or rarely it may

upon the extent of growth.

Diseases of

CHAPTER

the Cornea

ANATOMY AND PHYSIOLOGY

CORNEAL DYSTROPHIES

Applied anatomy

Anterior dystrophies

Stromal dystrophies

Applied physiology

Posterior dystrophies

CONGENITAL ANOMALIES

Ectatic conditions of cornea

INFLAMMATIONS OF THE CORNEA

Keratoconus

Ulcerative keratitis

Keratoglobus

Keratoconus posterior

Non-ulcerative keratitis

- Superficial

ABNORMALITIES OF CORNEAL

TRANSPARENCY

- Deep

Corneal oedema

CORNEAL DEGENERATIONS

Corneal opacity

Age-related corneal degenrations

Corneal vascularisation

Pathological corneal degenerations

KERATOPLASTY

Refractive power of the cornea is about

ANATOMY AND PHYSIOLOGY

dioptres, which is roughly three-fourth of the

total refractive power of the eye (60 dioptres).

APPLIED ANATOMY

Histology

The cornea is a transparent, avascular, watch-glass

Histologically, the cornea consists of five distinct

like structure. It forms anterior one-sixth of the outer

layers. From anterior to posterior these are: epithelium,

fibrous coat of the eyeball.

Bowman’s membrane, substantia propria (corneal

stroma), Descemet’s membrane and endothelium

Dimensions

(Fig. 5.1).

The anterior surface of cornea is elliptical with

1. Epithelium. It is of stratified squamous type and

an average horizontal diameter of 11.7 mm and

becomes continuous with the epithelium of bulbar

vertical diameter of 11 mm.

conjunctiva at the limbus. It consists of 5-6 layers of

The posterior surface of cornea is circular with

cells. The deepest (basal) layer is made up of columnar

an average diameter of 11.5 mm.

cells, next 2-3 layers of wing or umbrella cells and the

Thickness of cornea in the centre is about 0.52

most superficial two layers are of flattened cells.

mm while at the periphery it is 0.7 mm.

2. Bowman's membrane. This layer consists of

Radius of curvature. The central 5 mm area of the

acellular mass of condensed collagen fibrils. It is

cornea forms the powerful refracting surface of

about 12µm in thickness and binds the corneal stroma

the eye. The anterior and posterior radii of

anteriorly with basement membrane of the epithelium.

curvature of this central part of cornea are 7.8 mm

It is not a true elastic membrane but simply a

and 6.5 mm, respectively.

condensed superficial part of the stroma. It shows

Comprehensive OPHTHALMOLOGY

biomicroscopy appear as a mosaic. The cell density

of endothelium is around 3000 cells/mm² in young

adults, which decreases with the advancing age.

There is a considerable functional reserve for the

endothelium. Therefore, corneal decompensation

occurs only after more than 75 percent of the cells are

lost. The endothelial cells contain 'active-pump'

mechanism.

Blood supply

Cornea is an avascular structure. Small loops derived

from the anterior ciliary vessels invade its periphery

for about 1 mm. Actually these loops are not in the

cornea but in the subconjunctival tissue which

overlaps the cornea.

Nerve supply

Cornea is supplied by anterior ciliary nerves which

Fig. 5.1. Microscopic structure of the cornea.

are branches of ophthalmic division of the 5th cranial

considerable resistance to infection. But once

nerve. After going about 2 mm in cornea the nerves

destroyed, it does not regenerate.

lose their myelin sheath and divide dichotomously

and form three plexuses — the stromal, subepithelial

3. Stroma (substantia propria). This layer is about

and intraepithelial.

0.5 mm in thickness and constitutes most of the

cornea (90% of total thickness). It consists of collagen

APPLIED PHYSIOLOGY

fibrils (lamellae) embedded in hydrated matrix of

The two primary physiological functions of the

proteoglycans. The lamellae are arranged in many

cornea are (i) to act as a major refracting medium; and

layers. In each layer they are not only parallel to each

(ii) to protect the intraocular contents. Cornea fulfills

other but also to the corneal plane and become

these duties by maintaining its transparency and

continuous with scleral lamellae at the limbus. The

replacement of its tissues.

alternating layers of lamellae are at right angle to each

other. Among the lamellae are present keratocytes,

Corneal transparency

wandering macrophages, histiocytes and a few

The transparency is the result of :

leucocytes.

Peculiar arrangement of corneal lamellae (lattice

theory of Maurice),

4. Descemet's membrane (posterior elastic lamina).

Avascularity, and

The Descemet's membrane is a strong homogenous

Relative state of dehydration, which is maintained

layer which bounds the stroma posteriorly. It is very

by barrier effects of epithelium and endothelium

resistant to chemical agents, trauma and pathological

and the active bicarbonate pump of the

processes. Therefore, 'Descemetocele' can maintain

endothelium.

the integrity of eyeball for long. Descemet's membrane

For these processes, cornea needs some energy.

consists of collagen and glycoproteins. Unlike

Source of nutrients

Bowman's membrane it can regenerate. Normally it

1. Solutes (glucose and others) enter the cornea by

remains in a state of tension and when torn it curls

either simple diffusion or active transport through

inwards on itself. In the periphery it appears to end at

aqueous humour and by diffusion from the

the anterior limit of trabecular meshwork as

perilimbal capillaries.

Schwalbe's line (ring).

2. Oxygen is derived directly from air through the

5. Endothelium. It consists of a single layer of flat

tear film. This is an active process undertaken by

polygonal (mainly hexagonal) cells which on slit lamp

the epithelium.

DISEASES OF THE CORNEA

Metabolism of cornea

common conditions to be included in differential

The most actively metabolising layers of the cornea

diagnosis of neonatal cloudy cornea. The conditions

are epithelium and endothelium, the former being 10

are as follows:

times thicker than the latter requires a proportionately

Sclerocornea

larger supply of metabolic substrates. Like other

Tears in Descemet's membrane

tissues, the epithelium can metabolize glucose both

Ulcer

aerobically and anaerobically into carbon dioxide and

Metabolic conditions

water and lactic acid, respectively. Thus, under

Posterior corneal defect

anaerobic conditions lactic acid accumulates in the

Endothelial dystrophy

cornea.

Dermoid

CONGENITAL ANOMALIES

INFLAMMATIONS OF THE CORNEA

Megalocornea

Inflammation of the cornea (keratitis) is characterised

Horizontal diameter of cornea at birth is about 10 mm

by corneal oedema, cellular infiltration and ciliary

and the adult size of about 11.7 mm is attained by the

congestion.

age of 2 years. Megalocornea is labelled when the

Classification

horizontal diameter of cornea is of adult size at birth

or 13 mm or greater after the age of 2 years. The cornea

It is difficult to classify and assign a group to each

is usually clear with normal thickness and vision. The

and every case of keratitis; as overlapping or

condition is not progressive. Systemic association

concurrent findings tend to obscure the picture.

include Marfan's, Apert, Ehlers Danlos and Down

However, the following simplified topographical and

syndromes.

etiological classifications provide a workable

knowledge.

Differential diagnosis

1. Buphthalmos. In this condition IOP is raised and

Topographical (morphological) classification

the eyeball is enlarged as a whole. The enlarged

(A) Ulcerative keratitis (corneal ulcer)

cornea is usually associated with central or

Corneal ulcer can be further classified variously.

peripheral clouding and Descemet's tears (Haab's

striae).

1. Depending on location

2. Keratoglobus. In this condition, there is thinning

(a) Central corneal ulcer

and excessive protrusion of cornea, which seems

(b) Peripheral corneal ulcer

enlarged; but its diameter is usually normal.

2. Depending on purulence

(a) Purulent corneal ulcer or suppurative corneal

Microcornea

ulcer (most bacterial and fungal corneal ulcers

In microcornea, the horizontal diameter is less than

are suppurative).

10 mm since birth. The condition may occur as an

(b) Non-purulent corneal ulcers (most of viral,

isolated anomaly (rarely) or in association with

chlamydial and allergic corneal ulcers are

nanophthalmos

(normal small eyeball) or

non-suppurative).

microphthalmos (abnormal small eyeball).

3. Depending upon association of hypopyon

(a) Simple corneal ulcer (without hypopyon)

Cornea plana

(b) Hypopyon corneal ulcer

This is a rare anomaly in which bilaterally cornea is

4. Depending upon depth of ulcer

comparatively flat since birth. It may be associated

(a) Superficial corneal ulcer

with microcornea. Cornea plana usually results in

(b) Deep corneal ulcer

marked astigmatic refractive error.

Congenital cloudy cornea

(d) Perforated corneal ulcer

The acronym 'STUMPED' helps to remember the

5. Depending upon slough formation

Comprehensive OPHTHALMOLOGY

(a) Non-sloughing corneal ulcer

necrosis of the surrounding corneal tissue.

(b) Sloughing corneal ulcer

Pathologically it is characterised by oedema and

cellular infiltration. Common types of corneal ulcers

(B) Non-ulcerative keratitis

are described below.

1. Superficial keratitis

(a) Diffuse superficial keratitis

INFECTIVE KERATITIS

(b) Superficial punctate keratitis (SPK)

BACTERIAL CORNEAL ULCER

2. Deep keratitis

Being the most anterior part of eyeball, the cornea is

(a) Non-suppurative

exposed to atmosphere and hence prone to get

(i) Interstitial keratitis

infected easily. At the same time cornea is protected

(ii) Disciform keratitis

from the day-to-day minor infections by the normal

(iii) Keratitis profunda

defence mechanisms present in tears in the form of

(iv) Sclerosing keratitis

lysozyme, betalysin, and other protective proteins.

(b) Suppurative deep keratitis

Therefore, infective corneal ulcer may develop when:

(i) Central corneal abscess

either the local ocular defence mechanism is

(ii) Posterior corneal abscess

jeopardised, or

there is some local ocular predisposing disease,

Etiological classification

or host's immunity is compromised, or

Infective keratitis

the causative organism is very virulent.

(a) Bacterial

(b) Viral

Etiology

There are two main factors in the production of

(d) Chlamydial

purulent corneal ulcer:

(e) Protozoal

Damage to corneal epithelium; and

(f) Spirochaetal

Infection of the eroded area.

Allergic keratitis

However, following three pathogens can invade

(a) Phlyctenular keratitis

the intact corneal epithelium and produce ulceration:

(b) Vernal keratitis

Neisseria gonorrhoeae, Corynebacterium

diphtheriae and Neisseria meningitidis.

Trophic keratitis

1. Corneal epithelial damage. It is a prerequisite for

(a) Exposure keratitis

most of the infecting organisms to produce corneal

(b) Neuroparalytic keratitis

ulceration. It may occur in following conditions:

Corneal abrasion due to small foreign body,

(d) Atheromatous ulcer

misdirected cilia, concretions and trivial trauma

Keratitis associated with diseases of skin and

in contact lens wearers or otherwise.

mucous membrane.

ii.

Epithelial drying as in xerosis and exposure

Keratitis associated with systemic collagen

keratitis.

vascular disorders.

iii. Necrosis of epithelium as in keratomalacia.

Traumatic keratitis, which may be due to

iv. Desquamation of epithelial cells as a result of

mechanical trauma, chemical trauma, thermal

corneal oedema as in bullous keratopathy.

burns, radiations

v. Epithelial damage due to trophic changes as

Idiopathic keratitis e.g.,

in neuroparalytic keratitis.

(a) Mooren's corneal ulcer

2. Source of infection include:

(b) Superior limbic keratoconjunctivitis

Exogenous infection. Most of the times corneal

infection arises from exogenous source like

conjunctival sac, lacrimal sac (dacryocystitis),

ULCERATIVE KERATITIS

infected foreign bodies, infected vegetative

Corneal ulcer may be defined as discontinuation in

material and water-borne or air-borne infections.

normal epithelial surface of cornea associated with

ii.

From the ocular tissue. Owing to direct

DISEASES OF THE CORNEA

anatomical continuity, diseases of the

swelling of the lamellae by the imbibition of fluid and

conjunctiva readily spread to corneal epithelium,

the packing of masses of leucocytes between them.

those of sclera to stroma, and of the uveal tract

This zone of infiltration may extend to a considerable

to the endothelium of cornea.

distance both around and beneath the ulcer. At this

iii. Endogenous infection. Owing to avascular

stage, sides and floor of the ulcer may show grey

nature of the cornea, endogenous infections

infiltration and sloughing.

are of rare occurrence.

During this stage of active ulceration, there occurs

hyperaemia of circumcorneal network of vessels which

3. Causative organisms. Common bacteria associated

results into accumulation of purulent exudates on the

with corneal ulceration are: Staphylococcus aureus,

cornea. There also occurs vascular congestion of the

Pseudomonas pyocyanea, Streptococcus

iris and ciliary body and some degree of iritis due to

pneumoniae, E. coli, Proteus, Klebsiella, N.

absorption of toxins from the ulcer. Exudation into

gonorrhoea, N. meningitidis and C. diphtheriae.

the anterior chamber from the vessels of iris and ciliary

Pathogenesis and pathology of corneal ulcer

body may lead to formation of hypopyon.

Once the damaged corneal epithelium is invaded by

the offending agents the sequence of pathological

changes which occur during development of corneal

ulcer can be described under four stages, viz.,

infiltration, active ulceration, regression and

cicatrization. The terminal course of corneal ulcer

depends upon the virulence of infecting agent, host

defence mechanism and the treatment received.

Depending upon the prevalent circumstances the

course of corneal ulcer may take one of the three

forms:

(A) Ulcer may become localised and heal;

(B) Penetrate deep leading to corneal perforation;

corneal ulcer.

The salient pathological features of these are as

under:

[A] Pathology of localised corneal ulcer

1. Stage of progressive infiltration (Fig. 5.2A). It is

characterised by the infiltration of polymor-

phonuclear and/or lymphocytes into the epithelium

from the peripheral circulation supplemented by

similar cells from the underlying stroma if this tissue

is also affected. Subsequently necrosis of the

involved tissue may occur, depending upon the

virulence of offending agent and the strength of host

defence mechanism.

2. Stage of active ulceration (Fig. 5.2B). Active

ulceration results from necrosis and sloughing of the

Fig. 5.2. Pathology of corneal ulcer : A, stage of progressive

epithelium, Bowman's membrane and the involved

infiltration; B, stage of active ulceration; C, stage of

stroma. The walls of the active ulcer project owing to

regression; D, stage of cicatrization.

Comprehensive OPHTHALMOLOGY

Ulceration may further progress by lateral extension

resulting in diffuse superficial ulceration or it may

progress by deeper penetration of the infection

leading to Descemetocele formation and possible

corneal perforation. When the offending organism is

highly virulent and/or host defence mechanism is

jeopardised there occurs deeper penetration during

stage of active ulceration.

3. Stage of regression (Fig. 5.2C). Regression is

induced by the natural host defence mechanisms

(humoral antibody production and cellular immune

defences) and the treatment which augments the

normal host response. A line of demarcation develops

around the ulcer, which consists of leucocytes that

neutralize and eventually phagocytose the offending

organisms and necrotic cellular debris. The digestion

of necrotic material may result in initial enlargement

of the ulcer. This process may be accompanied by

superficial vascularization that increases the humoral

and cellular immune response. The ulcer now begins

to heal and epithelium starts growing over the edges.

4. Stage of cicatrization (Fig. 5.2D). In this stage

healing continues by progressive epithelization which

forms a permanent covering. Beneath the epithelium,

fibrous tissue is laid down partly by the corneal

fibroblasts and partly by the endothelial cells of the

new vessels. The stroma thus thickens and fills in

under the epithelium, pushing the epithelial surface

anteriorly.

The degree of scarring from healing varies. If the

ulcer is very superficial and involves the epithelium

Fig.

5.3.

Descemetocele

: A,

Diagrammatic

depiction;

only, it heals without leaving any opacity behind.

B.Clinical photographs.

When ulcer involves Bowman's membrane and few

superficial stromal lamellae, the resultant scar is called

iris-lens diaphragm moves forward. The effects of

a 'nebula'. Macula and leucoma result after healing of

perforation depend upon the position and size of

ulcers involving up to one-third and more than that

perforation. When the perforation is small and

of corneal stroma, respectively.

opposite to iris tissue, it is usually plugged and healing

[B] Pathology of perforated corneal ulcer

by cicatrization proceeds rapidly (Fig. 5.4). Adherent

leucoma is the commonest end result after such a

Perforation of corneal ulcer occurs when the ulcerative

catastrophe.

process deepens and reaches up to Descemet's

membrane. This membrane is tough and bulges out

[C] Pathology of sloughing corneal ulcer and

as Descemetocele (Fig. 5.3). At this stage, any

formation of anterior staphyloma

exertion on the part of patient, such as coughing,

When the infecting agent is highly virulent and/or

sneezing, straining for stool etc. will perforate the

body resistance is very low, the whole cornea sloughs

corneal ulcer. Immediately after perforation, the

with the exception of a narrow rim at the margin and

aqueous escapes, intraocular pressure falls and the

total prolapse of iris occurs. The iris becomes inflamed

DISEASES OF THE CORNEA

Clinical picture

In bacterial infections the outcome depends upon

the virulence of organism, its toxins and enzymes,

and the response of host tissue.

Broadly bacterial corneal ulcers may manifest as:

i. Purulent corneal ulcer without hypopyon; or

ii. Hypopyon corneal ulcer.

In general, following symptoms and signs may be

present :

Symptoms

1. Pain and foreign body sensation occurs due to

mechanical effects of lids and chemical effects of

toxins on the exposed nerve endings.

2. Watering from the eye occurs due to reflex

hyperlacrimation.

3. Photophobia, i.e., intolerance to light results from

stimulation of nerve endings.

4. Blurred vision results from corneal haze.

5. Redness of eyes occurs due to congestion of

circumcorneal vessels.

Signs

1. Lids are swollen.

2. Marked blepharospasm may be there.

3. Conjunctiva is chemosed and shows conjunct-

ival hyperaemia and ciliary congestion.

4. Corneal ulcer usually starts as an epithelial defect

associated with greyish-white circumscribed

infiltrate (seen in early stage). Soon the epithelial

defect and infiltrate enlarges and stromal oedema

develops. A well established bacterial ulcer is

Fig. 5.4. Perforated

corneal ulcer

with prolapse

iris:

characterized by (Fig. 5.5):

A, diagrammatic depiction; B, clinical photograph.

Yellowish-white area of ulcer which may be oval

or irregular in shape.

and exudates block the pupil and cover the iris

surface; thus a false cornea is formed. Ultimately

these exudates organize and form a thin fibrous layer

over which the conjunctival or corneal epithelium

rapidly grows and thus a pseudocornea is formed.

Since the pseudocornea is thin and cannot withstand

the intraocular pressure, so it usually bulges forward

along with the plastered iris tissue. This ectatic cicatrix

is called anterior staphyloma which, depending upon

its extent, may be either partial or total. The bands of

scar tissue on the staphyloma vary in breadth and

thickness, producing a lobulated surface often

blackened with iris tissue which resembles a bunch

Fig. 5.5. Bacterial corneal ulcer without hypopyon.

of black grapes (hence the name staphyloma).

Comprehensive OPHTHALMOLOGY

Margins of the ulcer are swollen and over hanging.

hypopyon corneal ulcer caused by pneumococcus is

Floor of the ulcer is covered by necrotic material.

called ulcus serpens.

Source of infection for pneumococcal infection is

Stromal oedema is present surrounding the ulcer

usually the chronic dacryocystitis.

area.

Factors predisposing to development of hypopyon.

Characteristic features produced by some of the

Two main factors which predispose to development

causative bacteria are as follows:

of hypopyon in a paitent with corneal ulcer are, the

Staphylococal aureus and streptococcus

virulence of the infecting organism and the resistance

pneumoniae usually produce an oval, yellowish

of the tissues. Hence, hypopyon ulcers are much more

white densely opaque ulcer which is surrounded

common in old debilitated or alcoholic subjects.

by relatively clear cornea.

Mechanism of development of hypopyon. Corneal

Pseudomonas species usually produce an irregular

ulcer is often associated with some iritis owing to

sharp ulcer with thick greenish mucopurulent

diffusion of bacterial toxins. When the iritis is severe

exudate, diffuse liquefactive necrosis and

the outpouring of leucocytes from the vessels is so

semiopaque (ground glass) surrounding cornea.

great that these cells gravitate to the bottom of the

Such ulcers spread very rapidly and may even

anterior chamber to form a hypopyon. Thus, it is

perforate within 48 to 72 hours.

important to note that the hypopyon is sterile since

Enterobacteriae (E. coli, Proteus sp., and Kleb-

the outpouring of polymorphonuclear cells is due to

siella sp.) usually produce a shallow ulcer with

the toxins and not due to actual invasion by bacteria.

greyish white pleomorphic suppuration and

Once the ulcerative process is controlled, the

diffuse stromal opalescence. The endotoxins

hypopyon is absorbed.

produced by these Gram -ve bacilli may produce

ring-shaped corneal infilterate.

Clinical features

Anterior chamber may or may not show pus

Symptoms are the same as described above for

(hypopyon). In bacterial corneal ulcers the

bacterial corneal ulcer. However, it is important to note

hypopyon remains sterile so long as the

that during initial stage of ulcus serpens there is

Descemet's membrane is intact.

remarkably little pain. As a result the treatment is often

Iris may be slightly muddy in colour.

undully delayed.

Signs. In general the signs are same as described

Pupil may be small due to associated toxin-

above for the bacterial ulcer. Typical features of ulcus

induced iritis.

serpens are :

Intraocular pressure may some times be raised

Ulcus serpens is a greyish white or yellowish

(inflammatory glaucoma).

disc shaped ulcer occuring near the centre of

Hypopyon corneal ulcer

cornea (Fig. 5.6).

Etiopathogenesis

The ulcer has a tendency to creep over the

cornea in a serpiginous fashion. One edge of the

Causative organisms. Many pyogenic organisms

(staphylococci, streptococci, gonococci, Moraxella)

ulcer, along which the ulcer spreads, shows more

infiltration. The other side of the ulcer may be

may produce hypopyon, but by far the most

undergoing simultaneous cicatrization and the

dangerous are pseudomonas pyocyanea and

pneumococcus.

edges may be covered with fresh epithelium.

Thus, any corneal ulcer may be associated with

Violent iridocyclitis is commonly associated with

hypopyon, however, it is customary to reserve the

a definite hypopyon.

term 'hypopyon corneal ulcer' for the characteristic

Hypopyon increases in size very rapidly and

ulcer caused by pneumococcus and the term 'corneal

often results in secondary glaucoma.

ulcer with hypopyon' for the ulcers associated with

Ulcer spreads rapidly and has a great tendency

hypopyon due to other causes. The characteristic

for early perforation.

DISEASES OF THE CORNEA

3. Descemetocele. Some ulcers caused by virulent

organisms extend rapidly up to Descemet's membrane,

which gives a great resistance, but due to the effect

of intraocular pressure it herniates as a transparent

vesicle called the descemetocele or keratocele

(Fig.5.3). This is a sign of impending perforation and

is usually associated with severe pain.

4. Perforation of corneal ulcer. Sudden strain due

to cough, sneeze or spasm of orbicularis muscle may

convert impending perforation into actual perforation

(Fig. 5.4). Following perforation, immediately pain is

decreased and the patient feels some hot fluid

(aqueous) coming out of eyes.

Sequelae of corneal perforation include :

Prolapse of iris. It occurs immediately following

perforation in a bid to plug it.

ii.

Subluxation or anterior dislocation of lens

may occur due to sudden stretching and rupture

of zonules.

iii. Anterior capsular cataract. It is formed when

the lens comes in contact with the ulcer following

a perforation in the pupillary area.

iv. Corneal fistula. It is formed when the perforation

in the pupillary area is not plugged by iris and

is lined by epithelium which gives way

repeatedly. There occurs continuous leak of

aqueous through the fistula.

v. Purulent uveitis, endophthalmitis or even

panophthalmitis may develop due to spread of

Fig.

5.6. Hypopyon

corneal ulcer

: A, Diagrammatic

intraocular infection.

depiction; B, Clinical photograph.

vi. Intraocular haemorrhage in the form of either

vitreous haemorrhage or expulsive choroidal

Management

haemorrhage may occur in some patients due to

Management of hypopyon corneal ulcer is same as

sudden lowering of intraocular pressure.

for other bacterial corneal ulcer. Special points which

5. Corneal scarring. It is the usual end result of

need to be considered are :

healed corneal ulcer. Corneal scarring leads to

Secondary glaucoma should be anticipated and

permanent visual impairment ranging from slight

treated with 0.5% timolol maleate, B.I.D. eye drops

blurring to total blindness. Depending upon the

and oral acetazolamide.

clinical course of ulcer, corneal scar noted may be

Source of infection, i.e., chronic dacryocystitis if

nebula, macula, leucoma, ectatic cicatrix or kerectasia,

detected, should be treated by dacryocystectomy.

adherent leucoma or anterior staphyloma (for details

Complications of corneal ulcer

see pages 122).

1. Toxic iridocyclitis. It is usually associated with

Management of a case of corneal ulcer

cases of purulent corneal ulcer due to absorption of

toxins in the anterior chamber.

[A] Clinical evaluation

2. Secondary glaucoma. It occurs due to fibrinous

Each case with corneal ulcer should be subjected to:

exudates blocking the angle of anterior chamber

1. Thorough history taking to elicit mode of onset,

(inflammatory glaucoma).

duration of disease and severity of symptoms.

Comprehensive OPHTHALMOLOGY

2. General physical examination, especially for

[C] Treatment

built, nourishment, anaemia and any immuno-

I. Treatment of uncomplicated corneal ulcer

compromising disease.

Bacterial corneal ulcer is a vision threatening

3. Ocular examination should include:

condition and demands urgent treatment by

Diffuse light examination for gross lesions of

identification and eradication of causative bacteria.

the lids, conjunctiva and cornea including

Treatment of corneal ulcer can be discussed under

testing for sensations.

three headings:

ii.

Regurgitation test and syringing to rule out

1. Specific treatment for the cause.

lacrimal sac infection.

2. Non-specific supportive therapy.

iii. Biomicroscopic examination after staining of

3. Physical and general measures.

corneal ulcer with 2 per cent freshlyprepared

aqueous solution of fluorescein dye or sterilised

1. The specific treatment

fluorescein impregnated filter paper strip to note

(a) Topical antibiotics. Initial therapy

(before

site, size, shape, depth, margin, floor and

results of culture and sensitivity are available)

vascularization of corneal ulcer. On

should be with combination therapy to cover

biomicroscopy also note presence of keratic

both gram-negative and gram-positive

precipitates at the back of cornea, depth and

organisms.

contents of anterior chamber, colour and pattern

It is preferable to start fortified gentamycin (14

of iris and condition of crystalline lens.

mg/ml) or fortified tobramycin

(14mg/ml)

eyedrops along with fortified cephazoline (50mg/

[B] Laboratory investigations

ml), every ½ to one hour for first few days and

(a) Routine laboratory investigations such as

then reduced to 2 hourly. Once the favourable

haemoglobin, TLC, DLC, ESR, blood sugar, complete

response is obtained, the fortified drops can be

urine and stool examination should be carried out in

substituted by more diluted commercially

each case.

available eye-drops, e.g. :

(b) Microbiological investigations. These studies

Ciprofloxacin (0.3%) eye drops, or

are essential to identify causative organism, confirm

Ofloxacin (0.3%) eye drops, or

the diagnosis and guide the treatment to be instituted.

Gatifloxacin (0.3%) eye drops.

Material for such investigations is obtained by

(b) Systemic antibiotics are usually not required.

scraping the base and margins of the corneal ulcer

However, a cephalosporine and an aminoglyco-

(under local anaesthesia, using 2 percent xylocaine)

side or oral ciprofloxacin (750 mg twice daily)

with the help of a modified Kimura spatula or by

may be given in fulminating cases with

simply using the bent tip of a 20 gauge hypodermic

perforation and when sclera is also involved.

needle. The material obtained is used for the following

investigations:

2. Non-specific treatment

Gram and Giemsa stained smears for possible

(a) Cycloplegic drugs. Preferably 1 percent atropine

identification of infecting organisms.

eye ointment or drops should be used to reduce

ii.

10 per cent KOH wet preparation for

pain from ciliary spasm and to prevent the

identification of fungal hyphae.

formation of posterior synechiae from secondary

iii. Calcofluor white

(CFW) stain preparation is

iridocyclitis. Atropine also increases the blood

viewed under fluorescence microscope for

supply to anterior uvea by relieving pressure

fungal filaments, the walls of which appear

on the anterior ciliary arteries and so brings

bright apple green.

more antibodies in the aqueous humour. It also

iv. Culture on blood agar medium for aerobic

reduces exudation by decreasing hyperaemia

organisms.

and vascular permeability. Other cycloplegic

v. Culture on Sabouraud's dextrose agar medium

which can be used is 2 per cent homatropine

for fungi.

eye drops.

DISEASES OF THE CORNEA

(b) Systemic analgesics and anti-inflammatory

imminent, the following additional measures may help

drugs such as paracetamol and ibuprofen relieve

to prevent perforation and its complications:

the pain and decrease oedema.

1. No strain. The patient should be advised to

avoid sneezing, coughing and straining during

healing of ulcer.

stool etc. He should be advised strict bed rest.

2. Pressure bandage should be applied to give

3. Physical and general measures

some external support.

(a) Hot fomentation. Local application of heat

3. Lowering of intraocular pressure by

(preferably dry) gives comfort, reduces pain

simultaneous use of acetazolamide 250 mg QID

and causes vasodilatation.

orally, intravenous mannitol (20%) drip stat, oral

(b) Dark goggles may be used to prevent

glycerol twice a day, 0.5% timolol eyedrops twice

photophobia.

a day, and even paracentesis with slow evacuation

of aqueous from the anterior chamber may be

soothing effect.

performed if required.

II. Treatment of non-healing corneal ulcer

4. Tissue adhesive glue such as cynoacrylate is

helpful in preventing perforation.

If the ulcer progresses despite the above therapy the

5. Conjunctival flap. The cornea may be covered

following additional measures should be taken:

completely or partly by a conjunctival flap to

Removal of any known cause of non-healing

give support to the weak tissue.

ulcer. A thorough search for any already missed

6. Bandage soft contact lens may also be used.

cause not allowing healing should be made and

7. Penetrating therapeutic keratoplasty

(tectonic

when found, such factors should be eliminated.

graft) may be undertaken in suitable cases, when

Common causes of non-healing ulcers are as

available.

under:

i. Local causes. Associated raised intraocular

IV. Treatment of perforated corneal ulcer

pressure, concretions, misdirected cilia,

Best is to prevent perforation. However, if perforation

impacted foreign body, dacryocystitis,

has occurred, immediate measures should be taken

inadequate therapy, wrong diagnosis,

to restore the integrity of perforated cornea.

lagophthalmos and excessive vascularization

Depending upon the size of perforation and

of ulcer.

availability, measures like use of tissue adhesive glues,

ii. Systemic causes: Diabetes mellitus, severe

covering with conjunctival flap, use of bandage soft

anaemia, malnutrition, chronic debilitating

contact lens or therapeutic keratoplasty should be

diseases and patients on systemic steroids.

undertaken. Best is an urgent therapeutic

Mechanical debridement of ulcer to remove

keratoplasty.

necrosed material by scraping floor of the ulcer

with a spatula under local anaesthesia may hasten

Marginal catarrhal ulcer

the healing.

These superificial ulcers situated near the limbus are

Cauterisation of the ulcer may also be considered

frequently seen especially in old people.

in non-responding cases. Cauterisation may be

Etiology

performed with pure carbolic acid or 10-20 per

Marginal catarrhal ulcer is thought to be caused by a

cent trichloracetic acid.

hypersensitivity reaction to staphylococcal toxins. It

Bandage soft contact lens may also help in

occurs in association with chronic staphylococcal

healing.

blepharoconjunctivitis. Moraxella and Haemophilus

Peritomy, i.e., severing of perilimbal conjunctival

are also known to cause such ulcers.

vessels may be performed when excessive corneal

vascularization is hindering healing.

Clinical features

III. Treatment of impending perforation

1. Patient usually presents with mild ocular irritation,

When ulcer progresses and perforation seems

pain, photophobia and watering.

100

Comprehensive OPHTHALMOLOGY

2. The ulcer is shallow, slightly infiltrated and often

vegetable matter. Common sufferers are field

multiple, usually associated with staphylococcal

workers especially during harvesting season.

conjunctivitis (Fig. 5.7).

ii. Injury by animal tail is another mode of

infection.

iii. Secondary fungal ulcers are common in

patients who are immunosuppressed

systemically or locally such as patients

suffering from dry eye, herpetic keratitis,

bullous keratopathy or postoperative cases of

keratoplasty.

3. Role of antibiotics and steroids. Antibiotics

disturb the symbiosis between bacteria and fungi;

and the steroids make the fungi facultative pathogens

which are otherwise symbiotic saprophytes.

Therefore, excessive use of these drugs predisposes

the patients to fungal infections.

Clinical features

Fig. 5.7. Marginal corneal ulcer in a patient with acute

Symptoms are similar to the central bacterial corneal

conjunctivitis.

ulcer (see page 95), but in general they are less marked

than the equal-sized bacterial ulcer and the overall

3. Soon vascularization occurs followed by

course is slow and torpid.

resolution. Recurrences are very common.

Signs. A typical fungal corneal ulcer has following

Treatment

salient features (Fig. 5.8):

1. A short course of topical corticosteroid drops

Corneal ulcer is dry-looking, greyish white, with

along with adequate antibiotic therapy often heals

elevated rolled out margins.

the condition.

Delicate feathery finger-like extensions are present

2. Adequate treatment of associated blepharitis and

into the surrounding stroma under the intact

chronic conjunctivitis is important to prevent

epithelium.

recurrences.

A sterile immune ring (yellow line of demarcation)

may be present where fungal antigen and host

MYCOTIC CORNEAL ULCER

antibodies meet.

The incidence of suppurative corneal ulcers caused

Multiple, small satellite lesions may be present

by fungi has increased in the recent years due to

around the ulcer.

injudicious use of antibiotics and steroids.

Etiology

1. Causative fungi. The fungi which may cause

corneal infections are :

i. Filamentous fungi e.g., Aspergillus, Fusarium,

Alternaria, Cephalosporium, Curvularia and

Penicillium.

ii. Yeasts e.g., Candida and Cryptococcus.

(The fungi more commonly responsible for mycotic

corneal ulcers are Aspergillus (most common),

Candida and Fusarium).

2. Modes of infection

i. Injury by vegetative material such as crop

leaf, branch of a tree, straw, hay or decaying

Fig. 5.8. Fungal corneal ulcer.

DISEASES OF THE CORNEA

101

Usually a big hypopyon is present even if the

Common viral infections include herpes simplex

ulcer is very small. Unlike bacterial ulcer, the

keratitis, herpes zoster ophthalmicus and adenovirus

hypopyon may not be sterile as the fungi can

keratitis.

penetrate into the anterior chamber without

perforation.

HERPES SIMPLEX KERATITIS

Perforation in mycotic ulcer is rare but can occur.

Ocular infections with herpes simplex virus (HSV) are

Corneal vascularization is conspicuously absent.

extremely common and constitute herpetic

keratoconjunctivitis and iritis.

Diagnosis

Etiology

1. Typical clinical manifestations associated with

Herpes simplex virus (HSV). It is a DNA virus. Its

history of injury by vegetative material are

only natural host is man. Basically HSV is

diagnostic of a mycotic corneal ulcer.

epitheliotropic but may become neurotropic.

2. Chronic ulcer worsening in spite of most efficient

According to different clinical and immunological

treatment should arouse suspicion of mycotic

properties, HSV is of two types: HSV type I typically

involvement.

causes infection above the waist and HSV type II

3. Laboratory investigations required for

below the waist (herpes genitalis). HSV-II has also

confirmation, include examination of wet KOH,

been reported to cause ocular lesions.

Calcofluor white, Gram's and Giemsa- stained films

for fungal hyphae and culture on Sabouraud's

Mode of Infection

agar medium.

HSV-1 infection. It is acquired by kissing or

coming in close contact with a patient suffering

Treatment

from herpes labialis.

I. Specific treatment includes antifungal drugs:

HSV-II infection. It is transmitted to eyes of

1. Topical antifungal eye drops should be used

neonates through infected genitalia of the mother.

for a long period

(6 to

8 weeks). These

include :

Ocular lesions of herpes simplex

Natamycin (5%) eye drops

Ocular involvement by HSV occurs in two forms,

Fluconazol (0.2%) eye drops

primary and recurrent; with following lesions:

Nystatin (3.5%) eye ointment.

[A] Primary herpes

For details see page 422.

1. Skin lesions

2. Systemic antifungal drugs may be required for

2. Conjunctiva-acute follicular conjunctivitis

severe cases of fungal keratitis. Tablet

3. Cornea

fluconazole or ketoconazole may be given for

Fine epithelial punctate keratitis

2-3 weeks.

II. Non specific treatment. Non-specific treatment

ii. Coarse epithelial punctate keratitis

and general measures are similar to that of bacterial

iii. Dendritic ulcer

corneal ulcer (see page 98).

[B] Recurrent herpes

III. Therapeutic penetrating keratoplasty may be

1. Active epithelial keratitis

required for unresponsive cases.

Punctate epthelial keratitis

VIRAL CORNEAL ULCERS

ii.

Dendritic ulcer

iii. Geographical ulcer

Incidence of viral corneal ulcers has become much

2. Stromal keratitis

greater especially because of the role of antibiotics

in eliminating the pathogenic bacterial flora. Most of

Disciform keratitis

the viruses tend to affect the epithelium of both the

ii.

Diffuse stromal necrotic keratitis

conjunctiva and cornea, hence the typical viral

3. Trophic keratitis

(meta-herpetic)

lesions constitute the viral keratoconjunctivitis.

4. Herpetic iridocyclitis

102

Comprehensive OPHTHALMOLOGY

[A] Primary ocular herpes

of steroids in dendritic ulcer hastens the formation

Primary infection (first attack) involves a nonimmune

of geographical ulcer.

person. It typically occurs in children between 6

Symptoms of epithelial keratitis are: photophobia

months and 5 years of age and in teenagers.

lacrimation, pain.

Treatment of epithelial keratitis

Clinical features

1. Skin lesions. Vesicular lesions may occur

I. Specific treatment

involving skin of lids, periorbital region and the

1. Antiviral drugs are the first choice presently.

lid margin (vesicular blepharitis).

Always start with one drug first and see the response.

2. Acute follicular conjunctivitis with regional

Usually after 4 days the lesion starts healing which is

lymphadenitis is the usual and sometimes the

completed by 10 days. After healing, taper the drug

only manifestation of the primary infection.

and withdraw in 5 days. If after 7 days of initial therapy,

3. Keratitis. Cornea is involved in about 50 percent

there is no response, it means the virus is resistant to

of the cases. The keratitis can occur as a coarse

this drug. So change the drug and/or do mechanical

punctate or diffuse branching epithelial keratitis

debridement. Commonly used antiviral drugs with

that does not usually involve the stroma.

their dose regime is given below (for details see page

Primary infection is usually self-limiting but the

420).

Acycloguanosine (Aciclovir) 3 percent ointment:

virus travels up to the trigeminal ganglion and

5 times a day until ulcer heals and then 3 times

establishes the latent infection.

a day for

5 days. It is least toxic and most

[B] Recurrent ocular herpes

commonly used antiviral drug. It penetrates intact

The virus which lies dormant in the trigeminal

corneal epithelium and stroma, achieving

ganglion, periodically reactivates and causes

therapeutic levels in aqueous humour, and can

recurrent infection.

therefore be used to treat herpetic keratitis.

Predisposing stress stimuli which trigger an attack

of herpetic keratitis include: fever such as malaria,

flu, exposure to ultraviolet rays, general ill- health,

emotional or physical exhaustion, mild trauma,

menstrual stress, following administration of topical

or systemic steroids and immunosuppressive agents.

1. Epithelial keratitis

i. Punctate epithelial keratitis

(Fig.

5.9A). The

initial epithelial lesions of recurrent herpes resemble

those seen in primary herpes and may be either in

the form of fine or coarse superficial punctate

lesions.

ii. Dendritic ulcer (Figs. 5.9B and C). Dendritic ulcer

is a typical lesion of recurrent epithelial keratitis.

The ulcer is of an irregular, zigzag linear branching

shape. The branches are generally knobbed at the

ends. Floor of the ulcer stains with fluorescein and

the virus-laden cells at the margin take up rose

bengal. There is an associated marked diminution of

corneal sensations.

iii. Geographical ulcer (Fig. 5.9D). Sometimes, the

Fig. 5.9. Lesions of recurrent herpes simplex keratitis:

branches of dendritic ulcer enlarge and coalesce to

A, Punctate epithelial keratitis; B and C, Dendritic ulcer;

form a large epithelial ulcer with a 'geographical' or

Diagramatics depiction and Clinical photograph

'amoeboid' configuration, hence the name. The use

D, Geographical ulcer and E; and Disciform keratitis.

DISEASES OF THE CORNEA

103

ii. Ganciclovir (0.15% gel), 5 times a day until ulcer

Treatment consists of diluted steroid eye drops

heals and then 3 times a day for 5 days. It is more

instilled 4-5 times a day with an antiviral cover

toxic than aciclovir.

(aciclovir 3%) twice a day. Steroids should be tapered

iii. Triflurothymidine 1 percent drops : Two hourly

over a period of several weeks. When disciform

until ulcer heals and then 4 times a day for 5

keratitis is present with an infected epithelial ulcer,

days.

antiviral drugs should be started 5-7 days before the

iv. Adenine arabinoside

(Vidarabine)

3 percent

steroids.

ointment: 5 times a day until ulcer heals and then

(b) Diffuse stromal necrotic keratitis. It is a type of

3 times a day for 5 days.

interstitial keratitis caused by active viral invasion

2. Mechanical debridement of the involved area along

and tissue destruction.

with a rim of surrounding healthy epithelium with the

Symptoms : Pain, photophobia and redness are

help of sterile cotton applicator under magnification

common symptom.

helps by removing the virus-laden cells.

Signs. It presents as necrotic, blotchy, cheesy white

Before the advent of antiviral drugs, it used to be

infiltrates that may lie under the epithelial ulcer or

the treatment of choice. Now it is reserved for:

may present independently under the intact

resistant cases, cases with non-compliance and those

epithelium. It may be associated with mild iritis and

allergic to antiviral drugs.

keratic precipitates. After several weeks of

smouldering inflammation, stromal vascularization

II. Non-specific supportive therapy and physical and

may occur.

general measures are same as for bacterial corneal

Treatment is similar to disciform keratitis but

ulcer (see page 98).

frequently the results are unsatisfactory.

2. Stromal keratitis

Keratoplasty should be deferred until the eye has

(a) Disciform keratitis

been quiet with little or no steroidal treatment for

several months; because viral interstitial keratitis is

Pathogenesis. It is due to delayed hypersensitivity

the form of herpes which is most likely to recur in a

reaction to the HSV antigen. There occurs low grade

new graft.

stromal inflammation and damage to the underlying

endothelium. Endothelial damage results in corneal

3. Metaherpetic keratitis

oedema due to imbibation of aqueous humour.

Metaherpetic keratitis (Epithelial sterile trophic

Signs. Disciform keratitis is characterized by (Fig.

ulceration) is not an active viral disease, but is a

5.9E):

mechanical healing problem (similar to recurrent

Focal disc-shaped patch of stromal oedema

traumatic erosions) which occurs at the site of a

without necrosis,

previous herpetic ulcer.

Folds in Descemet's membrane,

Clinically it presents as an indolent linear or

Keratic precipitates,

ovoid epithelial defect.

Ring of stromal infilterate (Wessley immune ring)

Treatment is aimed at promoting healing by use

may be present surrounding the stromal oedema.

of lubricants (artificial tears), bandage soft contact

It signifies the junction between viral antigen and

lens and lid closure (tarsorrhaphy).

host antibody.

Corneal sensations are diminished.

HERPES ZOSTER OPHTHALMICUS

Intraocular pressure (IOP) may be raised despite

Herpes zoster ophthalmicus is an acute infection of

only mild anterior uveitis. In severe cases, anterior

Gasserian ganglion of the fifth cranial nerve by the

uveitis may be marked.

varicella-zoster virus

(VZV). It constitutes

Sometimes epithelial lesions may be associated

approximately 10 percent of all cases of herpes zoster.

with disciform keratitis.

Important note. During active stage diminished

Etiology

corneal sensations and keratic precipitates are the

Varicella -zoster virus. It is a DNA virus and produces

differentiating points from other causes of stromal

acidophilic intranuclear inclusion bodies. It is

oedema.

neurotropic in nature.

104

Comprehensive OPHTHALMOLOGY

Mode of infection. The infection is contracted in

childhood, which manifests as chickenpox and the

child develops immunity. The virus then remains

dormant in the sensory ganglion of trigeminal nerve.

It is thought that, usually in elderly people (can occur

at any age) with depressed cellular immunity, the virus

reactivates, replicates and travels down along one or

more of the branches of the ophthalmic division of

the fifth nerve.

Clinical features

z In herpes zoster ophthalmicus, frontal nerve is

more frequently affected than the lacrimal and

nasociliary nerves.

Fig. 5.10. Cutaneous lesions of herpes

z About

50 percent cases of herpes zoster

zoster ophthalmicus.

ophthalmicus get ocular complications.

z The Hutchinson's rule, which implies that ocular

diminishes with the subsidence of eruptive phase;

involvement is frequent if the side or tip of nose

but sometimes it may persist for years with little

presents vesicles

(cutaneous involvement of

diminution of intensity. There occurs some anaesthesia

nasociliary nerve), is useful but not infallible.

of the affected skin which when associated with

z Lesions of herpes zoster are strictly limited to

continued post-herpetic neuralgia is called

one side of the midline of head.

anaesthesia dolorosa.

Clinical phases of H. zoster ophthalmicus are :

C. Ocular lesions. Ocular complications usually

i. Acute, which may totally resolve.

appear at the subsidence of skin eruptions and may

ii. Chronic, which may persist for years.

present as a combination of two or more of the

iii. Relapsing, where the acute or chronic lesions

following lesions:

reappear sometimes years later.

1. Conjunctivitis is one of the most common

Clinical features of herpes zoster ophthalmicus

complication of herpes zoster. It may occur as

include general features, cutaneous lesions and

mucopurulent conjunctivitis with petechial

ocular lesions. In addition, there may be associated

haemorrhages or acute follicular conjunctivitis with

other neurological complications as described below:

regional lymphadenopathy. Sometimes, severe

A. General features. The onset of illness is sudden

necrotizing membranous inflammation may be seen.

with fever, malaise and severe neuralgic pain along

2. Zoster keratitis occurs in 40 percent of all patients

the course of the affected nerve. The distribution of

and sometimes may precede the neuralgia or skin

pain is so characteristic of zoster that it usually

lesions. It may occur in several forms, which in order

arouses suspicion of the nature of the disease before

of chronological clinical occurrence are (Fig. 5.11) :

appearance of vesicles.

z Fine or coarse punctate epithelial keratitis.

B. Cutaneous lesions. Cutaneous lesions (Fig. 5.10)

z Microdendritic epithelial ulcers. These unlike

in the area of distribution of the involved nerve appear

dendritic ulcers of herpes simplex are usually

usually after 3-4 days of onset of the disease. To

peripheral and stellate rather than exactly dendritic

begin with, the skin of lids and other affected areas

in shape. It contrast to Herpes simplex dendrites,

become red and oedematous (mimicking erysipelas),

they have tapered ends which lack bulbs.

followed by vesicle formation. In due course of time

z Nummular keratitis is seen in about one-third

vesicles are converted into pustules, which

number of total cases. It typically occurs as

subsequently burst to become crusting ulcers. When

multiple tiny granular deposits surrounded by a

crusts are shed, permanent pitted scars are left. The

halo of stromal haze.

active eruptive phase lasts for about 3 weeks. Main

z Disciform keratitis occurs in about 50 percent of

symptom is severe neuralgic pain which usually

cases and is always preceded by nummular keratitis.

DISEASES OF THE CORNEA

105

Neuroparalytic ulceration may occur as a

D. Associated neurological complications. Herpes

sequelae of acute infection and Gasserian ganglion

zoster ophthalmicus may also be associated with

destruction.

other neurological complications such as :

Exposure keratitis may supervene in some cases

1. Motor nerve palsies especially third, fourth, sixth

due to associated facial palsy.

and seventh.

Mucous plaque keratitis develops in 5% of cases

2. Optic neuritis occurs in about 1 percent of cases.

between 3rd and 5th months characterised by

3. Encephalitis occurs rarely with severe infection.

sudden development of elevated mucous plaque

with stain brilliantly with rose bengal.

Treatment

Therapeutic approach to herpes zoster ophthalmicus

should be vigorous and aimed at preventing severe

devastating ocular complications and promoting rapid

healing of the skin lesions without the formation of

massive crusts which result in scarring of the nerves

and postherpetic neuralgia. The following regime may

be followed:

I. Systemic therapy for herpes zoster

1. Oral antiviral drugs. These significantly decrease

pain, curtail vesiculation, stop viral progression

and reduce the incidence as well as severity of

keratitis and iritis. In order to be effective, the

treatment should be started immediately after the

onset of rash. It has no effect on post herpetic

neuralgia.

Acyclovir in a dose of 800 mg 5 times a day

for 10 days, or

Valaciclovir in a dose of 500mg TDS

Analgesics. Pain during the first 2 weeks of an

attack is very severe and should be treated by

Fig. 5.11. Types of zoster keratitis : A, Punctate epithelial

analgesics such as combination of mephenamic

keratitis; B, Microdendritic epithelial ulcer; C, Nummular

acid and paracetamol or pentazocin or even

keratitis; D, Disciform keratitis.

pethidine (when very severe).

Systemic steroids. They appear to inhibit

3. Episcleritis and scleritis occur in about one-half

development of post-herpetic neuralgia when

of the cases. These usually appear at the onset of the

given in high doses. However, the risk of high

rash but are frequently concealed by the overlying

doses of steroids in elderly should always be

conjunctivitis.

taken into consideration. Steroids are commonly

4. Iridocyclitis is of a frequent occurrence and may

recommended in cases developing neurological

or may not be associated with keratitis. There may be

complications such as third nerve palsy and

associated hypopyon and hyphaema

(acute

optic neuritis.

haemorrhagic uveitis).

Cimetidine in a dose of 300 mg QID for 2-3 weeks

5. Acute retinal necrosis may occurs in some cases.

starting within

48-72 hours of onset has also

6. Anterior segment necrosis and phthisis bulbi. It

been shown to reduce pain and pruritis in acute

may also result from zoster vasculitis and ischemia.

zoster - presumably by histamine blockade.

7. Secondary glaucoma. It may occur due to

trabeculitis in early stages and synechial angle

Amitriptyline should be used to relieve the

closure in late stages.

accompanying depression in acute phase.

106

Comprehensive OPHTHALMOLOGY

II. Local therapy for skin lesions

is the commonest situation recognised for

1. Antibiotic-corticosteroid skin ointment or lotions.

acanthamoeba infection in western countries.

These should be used three times a day till skin

2. Other situations include mild trauma associated

lesions heal.

with contaminated vegetable matter, salt water

2. No calamine lotion. Cool zinc calamine

diving, wind blown contaminant and hot tub use.

application, as advocated earlier, is better avoided,

Trauma with organic matter and exposure to

as it promotes crust formation.

muddy water are the major predisposing factors

in developing countries.

III. Local therapy for ocular lesions

3. Opportunistic infection. Acanthamoeba keratitis

1. For zoster keratitis, iridocyctitis and scleritis

can also occur as opportunistic infection in

i. Topical steroid eye drops 4 times a day.

patients with herpetic keratitis, bacterial keratitis,

ii. Cycloplegics such as cyclopentolate eyedrops

bullous keratopathy and neuroparalytic keratitis.

BD or atropine eye ointment OD.

iii. Topical acyclovir

3 percent eye ointment

Clinical features

should be instilled 5 times a day for about 2

Symptoms. These include very severe pain (out of

weeks.

proportion to the degree of inflammation), watering,

2. To prevent secondary infections topical antibiotics

photophobia, blepharospasm and blurred vision.

are used.

Signs. Acanthamoeba keratitis evolves over several

3. For secondary glaucoma

months as a gradual worsening keratitis with periods

0.5 percent timolol or 0.5% betaxolol drops BD.

of temporary remission. Presentation is markedly

ii. Acetazolamide 250 mg QID.

variable, making diagnosis difficult. Characterstic

4. For neuroparalytic corneal ulcer caused by

herpes zoster, lateral tarsorrhaphy should be

features are described below :

performed.

1. Initial lesions of acanthamoeba keratitis are in

5. For persistent epithelial defects use :

the form of limbitis, coarse, opaque streaks, fine

i. Lubricating artificial tear drops, and

epithelial and subepithelial opacities, and radial

ii. Bandage soft contact lens.

kerato-neuritis, in the form of infiltrates along

6. Keratoplasty. It may be required for visual

corneal nerves.

rehabilitation of zoster-patients with dense

2. Advanced cases show a central or paracentral

scarring. However, these are poor risk patients.

ring-shaped lesion with stromal infiltrates and an

overlying epithelial defect, ultimately presenting

PROTOZOAL KERATITIS

as ring abscess (Fig. 5.12). Hypopyon may also

ACANTHAMOEBA KERATITIS

be present.

Acanthamoeba keratitis has recently gained

Diagnosis

importance because of its increasing incidence,

1. Clinical diagnosis. It is difficult and usually made

difficulty in diagnosis and unsatisfactory treatment.

by exclusion with strong clinical suspicion out of the

Etiology

non-responsive patients being treated for herpetic,

Acanthamoeba is a free lying amoeba found in soil,

bacterial or fungal keratitis.

fresh water, well water, sea water, sewage and air. It

2. Laboratory diagnosis. Corneal scrapings may be

exists in trophozoite and encysted forms.

helpful in some cases as under:

Mode of infection. Corneal infection with

Potassium hydroxide(KOH) mount is reliable in

acanthamoeba results from direct corneal contact with

experienced hands for recognition of

any material or water contaminated with the organism.

acanthamoeba cysts.

Following situations of contamination have been

ii.

Calcofluor white stain is a fluorescent

described:

brightener which stains the cysts of

1. Contact lens wearers using home-made saline

acanthamoeba bright apple green under

(from contaminated tap water and saline tablets)

fluorescence microscope.

DISEASES OF THE CORNEA

107

miconazole. Duration of medical treatment is very

large (6 months to 1 year).

3. Penetrating keratoplasty is frequently required

in non-responsive cases.

ALLERGIC KERATITIS

1. Phlyctenular keratitis (page 78)

2. Vernal keratitis (page 75)

3. Atopic keratitis (page 76)

TROPHIC CORNEAL ULCERS

Trophic corneal ulcers develop due to disturbance in

metabolic activity of epithelial cells. This group

includes: (1) Neuroparalytic keratitis and (2) Exposure

keratitis.

NEUROPARALYTIC KERATITIS

Neuroparalytic keratitis occurs due to paralysis of

the sensory nerve supply of the cornea.

Causes

I. Congenital

1. Familial dysautonomia (Riley-Day syndrome)

2. Congenital insensitivity to Pain.

3. Anhidrotic ectodermal dysplasia.

II. Acquired

1. Following alcohol-block or electrocoagulation

of Gasserian ganglion or section of the sensory

Fig. 5.12. Ring infiltrate (A) and ring abscess (B) in a pa-

root of trigeminal nerve for trigeminal neuralgia.

tient with advanced acanthamoeba keratitis.

2. A neoplasm pressing on Gasserian ganglion.

3. Gasserian ganglion destruction due to acute

iii. Lactophenol cotton blue stained film is also

infection in herpes zoster ophthalmicus.

useful for demonstration of acanthamoeba cysts

4. Acute infection of Gasserian ganglion by

in the corneal scrapings.

herpes simplex virus.

iv. Culture on non-nutrient agar (E. coli enriched)

5. Syphilitic (luetic) neuropathy.

may show trophozoites within 48 hours, which

6. Involvement of corneal nerves in leprosy.

gradually turn into cysts.

7. Injury to Gasserian ganglion.

Treatment

Pathogenesis

It is usually unsatisfactory.

Exact pathogenesis is not clear; presumably, the

1. Non-specific treatment is on the general lines for

corneal ulcer (see page 98).

disturbances in the antidromic corneal reflex occur

2. Specific medical treatment includes:

(a)

0.1

due to fifth nerve paralysis. As a consequence

percent propamidine isethionate (Brolene) drops;

metabolic activity of corneal epithelium is disturbed,

(b) Neomycin drops;

leading to accumulation of metabolites; which in turn

biguanide

(0.01%-0.02% solution);

(d)

cause oedema and exfoliation of epithelial cells

chlorhexidine; (e) other drugs that may be useful

followed by ulceration. Corneal changes can occur in

are paromomycin and various topical and oral

the presence of a normal blink reflex and normal lacrimal

imidazoles such as fluconazole, itraconazole and

secretions.

108

Comprehensive OPHTHALMOLOGY

Clinical features

1. Characteristic features are no pain, no lacrimation,

Initial dessication occurs in the interpalpebral area

and complete loss of corneal sensations.

leading to fine punctate epithelial keratitis which is

2. Ciliary congestion is marked.

followed by necrosis, frank ulceration and

3. Corneal sheen is dull.

vascularization. Bacterial superinfection may cause

4. Initial corneal changes are in the form of punctate

deep suppurative ulceration which may even

perforate.

epithelial erosions in the inter-palpebral area

followed by ulceration due to exfoliation of corneal

Treatment

epithelium.

1. Prophylaxis. Once lagophthalmos is diagnosed

5. Relapses are very common, even the healed scar

following measures should be taken to prevent

quickly breaks down again.

exposure keratitis.

Frequent instillation of artificial tear

Treatment

eyedrops.

1. Initial treatment with antibiotic and atropine eye

Instillation of ointment and closure of lids by

ointment with patching is tried. Healing is usually

a tape or bandage during sleep.

very slow. Recently described treatment modality

Soft bandage contact lens with frequent

include topical nerve growth factor drops and

instillation of artificial tears is required in cases

amniotic membrane transplantation.

of moderate exposure.

2. If, however, relapses occur, it is best to perform

Treatment of cause of exposure: If possible

lateral tarsorrhaphy which should be kept for at

cause of exposure (proptosis, ectropion, etc)

least one year. Along with it prolonged use of

should be treated.

artificial tears is also recommended.

2. Treatment of corneal ulcer is on the general lines

(see page 98).

EXPOSURE KERATITIS

3. Tarsorrhaphy is invariably required when it is

Normally cornea is covered by eyelids during sleep

not possible to treat the cause or when recovery

and is constantly kept moist by blinking movements

of the cause (e.g., facial palsy) is not anticipated.

during awaking. When eyes are covered insufficiently

by the lids and there is loss of protective mechanism

KERATITIS ASSOCIATED WITH DISEASES

of blinking the condition of exposure keratopathy

OF SKIN AND MUCOUS MEMBRANE

(keratitis lagophthalmos) develops.

ROSACEA KERATITIS

Causes

Corneal ulceration is seen in about 10 percent cases

Following factors which produce lagophthalmos may

of acne rosacea, which is primarily a disease of the

lead to exposure keratitis:

sebaceous glands of the skin.

1. Extreme proptosis due to any cause will allow

Clinical features

inadequate closure of lids.

1. The condition typically occurs in elderly women

2. Bell's palsy or any other cause of facial palsy.

in the form of facial eruptions presenting as

3. Ectropion of severe degree .

butterfly configuration, predominantly involving

4. Symblepharon causing lagophthalmos.

the malar and nasal area of face.

5. Deep coma associated with inadequate closure

2. Ocular lesions include chronic blepharo-

of lids.

conjunctivitis and keratitis. Rosacea keratitis

6. Physiological lagophthalmos. Occasionally,

occurs as yellowish white marginal infiltrates,

lagophthalmos during sleep may occur in healthy

and small ulcers that progressively advance

individuals.

across the cornea and almost always become

heavily vascularised.

Pathogenesis

Due to exposure the corneal epithelium dries up

Treatment

followed by dessication. After the epithelium is cast

1. Local treatment. Rosacea keratitis responds to

off, invasion by infective organisms may occur.

topical steroids, but recurrences are very common.

DISEASES OF THE CORNEA

109

2. Systemic treatment. The essential and most

effective treatment of rosacea keratitis is a long

course of systemic tetracycline (250 mg QID × 3

weeks, TDS × 3 weeks, BID × 3 weeks, and once

a day for 3 months).

CORNEAL ULCER ASSOCIATED WITH

SYSTEMIC COLLAGEN VASCULAR DISEASES

Peripheral corneal ulceration and/or melting of corneal

tissue is not infrequent occurrence in patients

suffering from systemic diseases such as rheumatoid

arthritis, systemic lupus erythematosus, polyarteritis

nodosa and Wegener's granulomatosis.

Such corneal ulcers are usually indolent and

difficult to treat. Systemic treatment of the primary

disease may be beneficial.

IDIOPATHIC CORNEAL ULCERS

MOOREN'S ULCER

The Mooren's ulcer (chronic serpiginous or rodent

ulcer) is a severe inflammatory peripheral ulcerative

keratitis.

Etiology

Exact etiology is not known. Different views are :

1. It is an idiopathic degenerative conditon.

2. It may be due to an ischaemic necrosis resulting

from vasculitis of limbal vessels.

3. It may be due to the effects of enzyme collagenase

and proteoglyconase produced from conjunctiva.

4. Most probably it is an autoimmune disease

(antibodies against corneal epithelium have been

demonstrated in serum).

Fig. 5.13. Mooren's ulcer : A, diagrammatic depiction;

Clinical picture

B, clinical photograph.

Two clinical varieties of Mooren's ulcer have been

recognised.

It is a superficial ulcer which starts at the corneal

1. Benign form which is usually unilateral, affects

margin as patches of grey infiltrates which

the elderly people and is characterised by a

coalesce to form a shallow furrow over the whole

relative slow progress.

cornea.

2. Virulent type also called the progressive form is

The ulcer undermines the epithelium and

bilateral, more often occurs in younger patients.

superficial stromal lamellae at the advancing

The ulcer is rapidly progressive with a high

border, forming a characteristic whitish

incidence of scleral involvement.

overhanging edge. Base of the ulcer soon

Symptoms. These include severe pain, photophobia,

becomes vascularized. The spread may be self-

lacrimation and defective vision.

limiting or progressive.

Signs. Features of Mooren's ulcer are shown in

The ulcer rarely perforates and the sclera remains

Fig. 5.13.

uninvolved.

110

Comprehensive OPHTHALMOLOGY

Treatment

2. Chronic diffuse superficial keratitis

Since exact etiology is still unknown, its treatment is

It may be seen in rosacea, phlyctenulosis and is

highly unsatisfactory. Following measures may be

typically associated with pannus formation.

tried:

SUPERFICIAL PUNCTATE KERATITIS (SPK)

1. Topical corticosteroids instilled every 2-3 hours

are tried as initial therapy with limited success.

Superficial punctate keratitis is characterised by

2. Immunosuppressive therapy with systemic

occurrence of multiple, spotty lesions in the superficial

steroids may be of help. Immunosuppression

layers of cornea. It may result from a number of

with cyclosporin or other cytotoxic agents may

conditions, identification of which (causative

condition) might not be possible most of the times.

be quite useful in virulent type of disease.

3. Soft contact lenses have also been used with

Causes

some relief in pain.

Some important causes of superficial punctate

4. Lamellar or full thickness corneal grafts often

keratitis are listed here.

melt or vascularize.

Viral infections are the chief cause. Of these

more common are: herpes zoster, adenovirus

NON-ULCERATIVE KERATITIS

infections, epidemic keratoconjunctivitis,

Non-ulcerative keratitis can be divided into two

pharyngo-conjunctival fever and herpes simplex.

groups: (a) non-ulcerative superficial keratitis and

Chlamydial infections include trachoma and

(b) non-ulcerative deep keratitis.

inclusion conjunctivitis.

Toxic lesions e.g., due to staphylococcal toxin

NON-ULCERATIVE SUPERFICIAL KERATITIS

in association with blepharoconjunctivitis.

This group includes a number of conditions of varied

Trophic lesions e.g., exposure keratitis and

etiology. Here the inflammatory reaction is confined

neuroparalytic keratitis.

to epithelium, Bowman's membrane and superficial

Allergic lesions e.g., vernal keratoconjunctivitis.

Irritative lesions e.g., effect of some drugs

stromal lamellae. Non-ulcerative superficial keratitis

such as idoxuridine.

may present in two forms:

Disorders of skin and mucous membrane, such

Diffuse superficial keratitis and

as acne rosacea and pemphigoid.

Superficial punctate keratitis

Dry eye syndrome, i.e., keratoconjunctivitis sicca.

DIFFUSE SUPERFICIAL KERATITIS

Specific type of idiopathic SPK e.g., Thygeson's

superficial punctate keratitis and Theodore's

Diffuse inflammation of superficial layers of cornea

occurs in two forms, acute and chronic.

superior limbic keratoconjunctivitis.

10. Photo-ophthalmitis.

1. Acute diffuse superficial keratitis

Morphological types (Fig. 5.14)

Etiology. Mostly of infective origin, may be

1. Punctate epithelial erosions (multiple superficial

associated with staphylococcal or gonococcal

erosions).

infections.

2. Punctate epithelial keratitis.

Clinical features. It is characterised by faint diffuse

3. Punctate subepithelial keratitis.

epithelial oedema associated with grey farinaceous

4. Punctate combined epithelial and subepithelial

appearance being interspersed with relatively clear

keratitis.

area. Epithelial erosions may be formed at places. If

5. Filamentary keratitis.

uncontrolled, it usually converts into ulcerative

Clinical features

keratitis.

Superficial punctate keratitis may present as different

Treatment. It consists of frequent instillation of

morphological types as enumerated above. Punctate

antibiotic eyedrops such as tobramycin or gentamycin

epithelial lesions usually stain with fluorescein, rose

2-4 hourly.

bengal and other vital dyes. The condition mostly

DISEASES OF THE CORNEA

111

Clinical features

Typically, patient presents with severe burning

pain, lacrimation, photophobia, blepharospasm,

swelling of palpebral conjunctiva and retrotarsal

folds.

There is history of exposure to ultraviolet rays 4-

5 hours earlier.

On fluorescein staining multiple spots are

demonstrated on both corneas.

Prophylaxis

Crooker's glass which cuts off all infrared and

ultraviolet rays should be used by those who are

prone to exposure e.g., welding workers, cinema

operators etc.

Treatment

1. Cold compresses.

Fig.

5.14. Morphological types of superficial punctate

keratitis.

2. Pad and bandage with antibiotic ointment for 24

hours, heals most of the cases.

presents acutely with pain, photophobia and

3. Oral analgesics may be given if pain is intolerable.

lacrimation; and is usually associated with

4. Single dose of tranquilliser may be given to

conjunctivitis.

apprehensive patients.

Treatment

SUPERIOR LIMBIC KERATOCONJUNCTIVITIS

Treatment of most of these conditions is symptomatic.

Superior limbic keratoconjunctivitis of Theodore is

1. Topical steroids have a marked suppressive

the name given to inflammation of superior limbic,

effect.

bulbar and tarsal conjunctiva associated with

2. Artificial tears have soothing effect.

punctate keratitis of the superior part of cornea.

3. Specific treatment of cause should be instituted

whenever possible e.g., antiviral drugs in cases

Etiology

of herpes simplex.

Exact etiology is not known. It occurs with greater

frequency in patients with hyperthyroidism and is

PHOTO-OPHTHALMIA

more common in females.

Photo-ophthalmia refers to occurrence of multiple

Clinical features

epithelial erosions due to the effect of ultraviolet rays

Clinical course. It has a chronic course with

especially from 311 to 290µ.

remissions and exacerbations.

Causes

Symptoms include :

1. Exposure to bright light of a short circuit.

Bilateral ocular irritation.

2. Exposure to a naked arc light as in industrial

Mild photophobia, and redness in superior bulbar

welding and cinema operators.

conjunctiva.

3. Snow blindness due to reflected ultraviolet rays

Signs (Fig. 5.15) include

from snow surface.

Congestion of superior limbic, bulbar and tarsal

conjunctiva.

Pathogenesis

Punctate keratitis which stains with fluorescein

After an interval of 4-5 hours (latent period) of

and rose bengal stain is seen in superior part of

exposure to ultraviolet rays there occurs desqua-

cornea.

mation of corneal epithelium leading to formation of

Corneal filaments are also frequently seen in the

multiple epithelial erosions.

involved area.

112

Comprehensive OPHTHALMOLOGY

Etiology

Exact etiology is not known.

A viral origin has been suggested without any

conclusion.

An allergic or dyskeratotic nature also has been

suggested owing to its response to steroids.

Clinical features

Age and sex. It may involve all ages with no sex

predilection.

Laterality. Usually bilateral.

Course. It is a chronic disease characterised by

remissions and exacerbations.

Symptoms

It may be asymptomatic, but is usually associated

with foreign body sensation, photophobia and

lacrimation.

Signs

1. Conjunctiva is uninflamed (no conjunctivitis).

2. Corneal lesions. There are coarse punctate

epithelial lesions (snow flake) circular, oval or

stellate in shape, slightly elevated and situated in

the central part (pupillary area) of cornea. Each

lesion is a cluster of heterogeneous granular grey

dots.

Fig. 5.15. Superior limbic keratoconjunctivitis :

Treatment

diagramatic depiction; B, clinical photograph.

1. The disease is self-limiting with remissions and

may permanently disappear in a period of 5-6

Treatment

years.

1. Topical artificial tears.

2. During exacerbations the lesions and associated

2. Low doses of topical corticosteroids may reduce

symptoms usually respond quickly to topical

the symptoms temporarily.

steroids (so, should be tapered rapidly).

3. Faint diathermy of superior bulbar conjunctiva in

3. Therapeutic soft contact lenses may be required

a checker board pattern gives acceptable results.

4. Recession or resection of a 3-4 mm wide perilimbal

in steroid-resistant cases.

strip of conjunctiva from the superior limbus

FILAMENTARY KERATITIS

(from 10.30 to 1.30 O'clock position) may be

helpful if other measures fail.

It is a type of superficial punctate keratitis, associated

5. Therapeutic soft contact lenses for a longer period

with formation of corneal epithelial filaments.

may be helpful in healing the keratitis.

Pathogenesis

THYGESON'S SUPERFICIAL PUNCTATE

Corneal filaments which essentially consist of a tag

KERATITIS

of elongated epithelium are formed due to aberrant

epithelial healing. Therefore, any condition that leads

It is a type of chronic, recurrent bilateral superficial

punctate keratitis, which has got a specific clinical

to focal epithelial erosions may produce filamentary

identity.

keratopathy.

DISEASES OF THE CORNEA

113

Causes

INTERSTITIAL KERATITIS

The common conditions associated with filamentary

Interstitial keratitis denotes an inflammation of the

keratopathy are:

corneal stroma without primary involvement of the

1. Keratoconjunctivitis sicca (KCS).

epithelium or endothelium.

2. Superior limbic keratoconjunctivitis.

Causes. Its common causes are:

3. Epitheliopathy due to radiation keratitis.

Congenital syphilis

4. Following epithelial erosions as in herpes simplex

Tuberculosis

keratitis, Thygeson's superficial punctate keratitis,

Cogan's syndrome

recurrent corneal erosion syndrome and trachoma.

Acquired syphilis

5. Prolonged patching of the eye particularly

Trypanosomiasis

following ocular surgery like cataract.

Malaria

6. Systemic disorders like diabetes mellitus,

Leprosy

ectodermal dysplasia and psoriasis.

Sarcoidosis

7. Idiopathic.

Syphilitic (luetic) interstitial keratitis

Clinical features

Syphilitic interstitial keratitis is associated more

Symptoms. Patients usually experience moderate

frequently (90 percent) with congenital syphilis than

pain, ocular irritation, lacrimation and foreign body

the acquired syphilis. The disease is generally bilateral

sensation.

in inherited syphilis and unilateral in acquired

Signs. Corneal examination reveals.

syphilis. In congenital syphilis, manifestations

Filaments i.e., fine tags of elongated epithelium

develop between 5-15 years of age.

which are firmly attached at the base, intertwined

Pathogenesis

with mucus and degenerated cells. The filament

It is now generally accepted that the disease is a

is freely movable over the cornea.

manifestation of local antigen-antibody reaction. It

Superficial punctate keratitis of varying degree

is presumed that Treponema pallidum invades the

is usually associated with corneal filaments.

cornea and sensitizes it during the period of its general

diffusion throughout the body in the foetal stage.

Treatment

Later a small-scale fresh invasion by treponema or

1. Management of filaments include their mechanical

toxins excite the inflammation in the sensitized cornea.

debridement and patching for 24 hours followed

The inflammation is usually triggered by an injury or

by lubricating drops.

an operation on the eye.

2. Therapeutic soft contact lenses may be useful in

recurrent cases.

Clinical features

3. Treatment of the underlying cause to prevent

Interstitial keratitis characteristically forms one of the

recurrence.

late manifestations of congenital syphilis. Many a

time it may be a part of Hutchinson's triad, which

DEEP KERATITIS

includes: interstitial keratitis, Hutchinson's teeth and

vestibular deafness.

An inflammation of corneal stroma with or without

The clinical picture of interstitial keratitis can be

involvement of posterior corneal layers constitutes

divided into three stages: initial progressive stage,

deep keratitis, which may be non-suppurative or

florid stage and stage of regression.

suppurative.

Non-suppurative deep keratitis includes,

1. Initial progressive stage. The disease begins with

interstitial keratitis, disciform keratitis, keratitis

oedema of the endothelium and deeper stroma,

profunda and sclerosing keratitis.

secondary to anterior uveitis, as evidenced by the

Suppurative deep keratitis includes central

presence of keratic precipitates (KPs). There is

corneal abscess and posterior corneal abscess,

associated pain, lacrimation, photophobia,

which are usually metastatic in nature.

blepharospasm and circumcorneal injection followed

114

Comprehensive OPHTHALMOLOGY

by a diffuse corneal haze giving it a ground glass

is more frequently unilateral and sectorial (usually

appearance. This stage lasts for about 2 weeks.

involving a lower sector of cornea).

2. Florid stage. In this stage eye remains acutely

Treatment consists of systemic antitubercular drugs,

inflamed. Deep vascularization of cornea, consisting

topical steroids and cycloplegics.

of radial bundle of brush-like vessels develops. Since

Cogan's syndrome

these vessels are covered by hazy cornea, they look

dull reddish pink which is called 'Salmon patch

This syndrome comprises the interstitial keratitis of

unkown etiology, acute tinnitis, vertigo, and

appearance'. There is often a moderate degree of

deafness. It typically occurs in middle-aged adults

superficial vascularization. These vessels arising from

and is often bilateral.

the terminal arches of conjunctival vessels, run a short

distance over the cornea. These vessels and

Treatment consists of topical and systemic

conjunctiva heap at the limbus in the form of epulit.

corticosteroids. An early treatment usually prevents

This stage lasts for about 2 months.

permanent deafness and blindness.

3. Stage of regression. The acute inflammation

resolves with the progressive appearance of vascular

CORNEAL DEGENERATIONS

invasion. Clearing of cornea is slow and begins from

periphery and advances centrally. Resolution of the

Corneal degenerations refers to the conditions in

lesion leaves behind some opacities and ghost

which the normal cells undergo some degenerative

vessels. This stage may last for about 1 to 2 years.

changes under the influence of age or some

Diagnosis

pathological condition.

The diagnosis is usually evident from the clinical

CLASSIFICATION

profile. A positive VDRL or Treponema pallidum

[A] Depending upon location

immobilization test confirms the diagnosis.

I. Axial corneal degenerations

Treatment

1. Fatty degeneration

The treatment should include topical treatment for

2. Hyaline degeneration

keratitis and systemic treatment for syphilis.

3. Amyloidosis

1. Local treatment. Topical corticosteroid drops e.g.,

4. Calcific degeneration (Band keratopathy)

dexamethasone 0.1% drops every 2-3 hours. As the

5. Salzmann's nodular degeneration.

condition is allergic in origin, corneal clearing occurs

II. Peripheral degenerations

with steroids if started well in time and a useful vision

1. Arcus senilis

is obtained.

2. Vogt's white limbal girdle

Atropine eye ointment 1 percent 2-3 times a day.

3. Hassal-Henle bodies

Dark goggles to be used for photophobia.

4. Terrien's marginal degeneration

2. Keratoplasty is required in cases where dense

5. Mooren's ulcer

corneal opacities are left.

6. Pellucid marginal degeneration

7. Furrow degeneration

(senile marginal

2. Systemic treatment

degeneration).

Penicillin in high doses should be started to

[B] Depending upon etiology

prevent development of further syphilitic lesions.

I. Age related degenerations. Arcus senilis, Vogt's

However, an early treatment of congenital syphilis

white limbal girdle, Hassal-Henle bodies, Mosaic

usually does not prevent the onset of keratitis at

degeneration.

a later stage.

II. Pathological degenerations: Fatty degeneration,

Systemic steroids may be added in refractory

amyloidosis, calcific degeneration, Salzmann's

cases of keratitis.

nodular degeneration, Furrow degeneration,

Tuberculous interstitial keratitis

spheroidal degeneration, Pellucid marginal

The features of tubercular interstitial keratitis are

degeneration, Terrien's marginal degeneration,

similar to syphilitic interstitial keratitis except that it

Mooren's ulcer.

DISEASES OF THE CORNEA

115

I. AGE-RELATED DEGENERATIONS

II. PATHOLOGICAL DEGENERATIONS

Arcus senilis

Fatty degeneration (Lipoid keratopathy)

Arcus senilis refers to an annular lipid infiltration of

Fatty degeneration of cornea is characterised by

corneal periphery. This is an age-related change

whitish or yellowish deposits. The fat deposits mostly

occurring bilaterally in 60 percent of patients between

consist of cholesterol and fatty acids. Initially fat

40 and 60 years of age and in nearly all patients over

deposits are intracellular but some become

the age of 80. Sometimes, similar changes occur in

extracellular with necrosis of stromal cells. Lipid

young persons (arcus juvenilis) which may or may

keratopathy can be primary or secondary.

not be associated with hyperlipidemia.

1. Primary lipid keratopathy is a rare condition

which occurs in a cornea free of vascularization.

The arcus starts in the superior and inferior

Serum lipid levels are normal in such patients.

quadrants and then progresses circumferentially to

2. Secondary lipid keratopathy occurs in

form a ring which is about 1 mm wide. This ring of

vascularised corneas secondary to diseases such

opacity is separated from the limbus by a clear zone

as corneal infections, interstitial keratitis, ocular

(the lucid interval of Vogt) (Fig. 5.16). Sometimes

trauma, glaucoma, and chronic iridocyclitis.

there may be double ring of arcus.

Treatment is usually unsatisfactory. In some cases

slow resorption of lipid infiltrate can be induced by

argon laser photocoagulation of the new blood

vessels.

Hyaline degeneration

Hyaline degeneration of cornea is characterised by

deposition of hyaline spherules in the superficial

stroma and can be primary or secondary.

1. Primary hyaline degeneration is bilateral and

noted in association with granular dystrophy

(see page 118).

2. Secondary hyaline degeneration is unilateral and

associated with various types of corneal diseases

including old keratitis, long-standing glaucoma,

Fig. 5.16. Arcus senilis.

trachomatous pannus. It may be complicated by

recurrent corneal erosions.

Vogt's white limbal girdle

Treatment of the condition when it causes visual

It is also an age-related change seen frequently in

disturbance is keratoplasty.

elderly people. It appears as bilateral chalky white

opacities in the interpalpebral area both nasally and

Amyloid degeneration

temporally. There may or may not be a clear area

Amyloid degeneration of cornea is characterised by

between opacity and the limbus. The opacity is at the

deposition of amyloid material underneath its

level of Bowman's membrane.

epithelium. It is very rare condition and occurs in

Hassal-Henle bodies

primary (in a healthy cornea) and secondary forms

Hassal-Henle bodies are drop-like excrescences of

(in a diseased cornea).

hyaline material projecting into the anterior chamber

around the corneal periphery. These arise from

Calcific degeneration (Band Shape keratopathy)

Descemet's membrane. These form the commonest

Band shape keratopathy (BSK) is essentially a

senile change seen in the cornea. In pathological

degenerative change associated with deposition of

conditions they become larger and invade the central

calcium salts in Bowman's membrane, most superficial

area and the condition is called cornea guttata.

part of stroma and in deeper layers of epithelium.

116

Comprehensive OPHTHALMOLOGY

Etiology

2. Phototherapeutic keratectomy (PTK) with excimer

Ocular diseases. Band keratopathy is seen in

laser is very effective in clearing the cornea.

association with: chronic uveitis in adults, children

3. Keratoplasty may be performed when the band

with Still's disease, phthisis bulbi, chronic

keratopathy is obscuring useful vision.

glaucoma, chronic keratitis and ocular trauma.

Salzmann's nodular degeneration

Age related BSK is common and affects otherwise

healthy cornea.

Etiology. This condition occurs in eyes with recurrent

Metabolic conditions rarely associated with BSK

attacks of phlyctenular keratitis, rosacea keratitis and

include hypercalcaemia and chronic renal failure.

trachoma. The condition occurs more commonly in

Clinical features. It typically presents as a band-

women and is usually unilateral.

shaped opacity in the interpalpebral zone with a clear

Pathogenesis. In Salzmann's nodular degeneration,

interval between the ends of the band and the limbus

raised hyaline plaques are deposited between

(Fig. 5.17). The condition begins at the periphery and

epithelium and Bowman's membrane. There is

gradually progresses towards the centre. The opacity

associated destruction of Bowman's membrane and

is beneath the epithelium which usually remains intact.

the adjacent stroma.

Surface of this opaque band is stippled due to holes

Clinical features. Clinically, one to ten bluish white

in the calcium plaques in the area of nerve canals of

elevations (nodules), arranged in a circular fashion,

Bowman's membrane. In later stages, transparent

are seen within the cornea. Patient may experience

clefts due to cracks or tears in the calcium plaques

discomfort due to loss of epithelium from the surface

may also be seen.

of nodules. Visual loss occurs when nodules impinge

Treatment. It consists of :

on the central zone.

1. Chelation, i.e., chemical removal of deposited

Treatment is essentially by keratoplasty.

calcium salts is an effective treatment. First of all

corneal epithelium is scraped under local

Furrow degeneration (Senile marginal

anaesthesia. Then 0.01 molar solution of EDTA

degeneration)

(chelating agent) is applied to the denuded cornea

In this condition thinning occurs at the periphery of

with the help of a cotton swab for about 10

cornea leading to formation of a furrow. In the

minutes. This removes most of the deposited

presence of arcus senilis, the furrow occupies the

calcium. Pad and bandage is then applied for 2-

area of lucid interval of Vogt. Thinning occurs due to

3 days to allow the epithelium to regenerate.

fibrillar degeneration of the stroma.

Patient develops defective vision due to induced

astigmatism.

Treatment is usually not necessary.

Spheroid degeneration

(Climatic droplet keratopathy/Labrador keratopathy/

Bietti's nodular dystrophy)/corneal elastosis.

Etiology. It typically occurs in men who work out-

doors, especially in hostile climates. Its occurrence

has been related to exposure to ultraviolet rays and/

or ageing and /or corneal disease.

Clinical features. In this condition amber-coloured

spheroidal granules (small droplets) accumulate at

the level of Bowman's membrane and anterior stroma

Fig. 5.17. Band-shaped keratopathy in a patient with

in the interpalpebral zone. In marked degeneration,

chronic uveitis.

the vision is affected.

DISEASES OF THE CORNEA

117

Treatment in advanced cases is by corneal trans-

1. Epithelial basement membrane dystrophy

plantation.

2. Reis-Buckler's dystrophy.

3. Meesman's dystrophy.

Pellucid marginal degeneration

4. Recurrent corneal erosion syndrome.

It is characterised by corneal thinning involving the

5. Stocker-Holt dystrophy.

periphery of lower cornea. It induces marked

II. Stromal dystrophies

astigmatism which is corrected by scleral type contact

1. Granular (Groenouw's type I) dystrophy

lenses.

2. Lattice dystrophy

Terrien's marginal degeneration

3. Macular (Groenouw's type II) dystrophy

4. Crystalline (Schnyder's) dystrophy

Terrien's marginal degeneration is non-ulcerative

III. Posterior dystrophies, affecting primarily the

thinning of the marginal cornea.

corneal endothelium and Descemet's membrane.

Clinical features are as follows :

1. Cornea guttata

1. Predominantly affects males usually after 40 years

2. Fuchs' epithelial-endothelial dystrophy (late

of age.

hereditary endothelial dystrophy).

2. Mostly involves superior peripheral cornea.

3. Posterior polymorphous dystrophy

(of

3. Initial lesion is asymptomatic corneal opacifi-

Schlichting).

cation separated from limbus by a clear zone.

4. Congenital hereditary endothelial dystrophy

4. The lesion progresses very slowly over many

(CHED).

years with thinning and superficial vascularization.

Dense yellowish white deposits may be seen at

I. ANTERIOR DYSTROPHIES

the sharp leading edge. Patient experiences

irritation and defective vision (due to astigmatism).

Epithelial basement membrane dystrophy

Complications such as perforation (due to mild

Also known as Cogan's microcystic dystrophy and

trauma) and pseudopterygia may develop.

map-dot finger print dystrophy, is the most common

of all corneal dystrophies seen in working age adults.

Treatment is non-specific. In severe thinning, a patch

The typical lesions, involving corneal epithelium, are

of corneal graft may be required.

bilateral dot-like microcystic, or linear finger-print like

opacities. Most cases are asymptomatic. However,

about 10 percent patients develop recurrent corneal

CORNEAL DYSTROPHIES

erosions and experience severe disabling pain.

Corneal dystrophies are inherited disorders in which

Treatment consists of patching with plain ointment

for 1-2 days. The condition remits spontaneously,

the cells have some inborn defects due to which

pathological changes may occur with passage of time

but can recur.

leading to development of corneal haze in otherwise

Reis-Buckler dystrophy

normal eyes that are free from inflammation or

Also known as ring-shaped dystrophy (due to the

vascularization. There is no associated systemic

typical lesion) primarily involving the Bowman's layer

disease. Dystrophies occur bilaterally, manifesting

is a progressive corneal dystrophy occurring in

occasionally at birth, but more usually during first or

childhood. It has got autosomal dominant inheritance.

second decade and sometimes even later in life.

Most patients get frequent attacks of recurrent corneal

CLASSIFICATION

erosions that usually result in diffuse anterior

scarring.

Dystrophies are classified according to the anatomic

site most severely (primarily) involved, as follows:

Treatment. In early cases is same as that of recurrent

Anterior dystrophies (superficial dystrophies),

corneal erosions, i.e. by patching. However, most of

primarily affecting epithelium and Bowman's

the patients ultimately need lamellar or penetrating

layer.

keratoplasty.

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Comprehensive OPHTHALMOLOGY

Meesman's dystrophy

Lattice dystrophy

(Juvenile epithelial dystrophy)

Also known as 'Biber-Haab-Dimmer dystrophy. It is

It is characterised by the presence of tiny epithelial

an autosomal dominant disease characterised by

cysts.The disease occurs in early life and has

branching spider-like amyloid deposits forming an

autosomal dominant inheritance. In most cases,

irregular lattice work in the corneal stroma, sparing the

condition is asymptomatic and does not require

periphery. It appears at the age of 2 years, but the

treatment.

occurrence of recurrent erosions and progressive

clouding of central cornea is apparent by the age of 20

Recurrent corneal erosion syndrome

years. Soon, visual acuity is impaired. Usually

It is often described as a type of dystrophy that

penetrating keratoplasty is required by the age of 30-

typically follows trauma to cornea by finger nail or

40 years.

any other sharp edge. It has been shown that a lack

of basement membrane and hemidesmosomes in the

Schnyder's crystalline dystrophy

area of involvement, is the basic underlying cause.

It is an autosomal dominant dystrophy characterised

The condition is characterised by pain, photophobia,

by a round ring-shaped central corneal stromal opacity

lacrimation and blurring of vision on awakening in

due to deposition of fine needle-like cholesterol

the morning.

crystals, which may be white to yellow or

polychromatic in colour. The dystrophy appears in

Treatment. It consists of patching with plain ointment

early infancy or at birth or sometimes in the first

for 1-2 days. Hypertonic saline drops or ointment

decade of life. It is slowly progressive and usually

decrease attack of erosions by reducing epithelial

asymptomatic.

oedema. Severe cases may be treated by scraping the

whole epithelium followed by pressure patching.

III. POSTERIOR DYSTROPHIES

Cornea Guttata of vogt

Stocker-Holt dystrophy

This condition is characterised by drop-like

It is characterised by the presence of grey white dots

excrescences involving the entire posterior surface

and serpiginous lines between epithelium and

of Descemet's membrane. These are similar to Hassal-

Bowman's layer. The inheritance is autosomal

Henle bodies which represent the age change and

dominant. The condition may occur at any age from

are mainly found in the peripheral part. Cornea guttata

one to seventy years.

may occur independently or as a part of early stage

II. STROMAL DYSTROPHIES

of Fuch's dystrophy. The condition usually occurs in

old age and is more common in females than males. It

Granular dystrophy

rarely affects the vision and hence treatment is

Also known as 'Groenouw type I, is an autosomal

usually not required.

dominant dystrophy characterised by milky-granular

Fuch's epithelial-endothelial dystrophy

hyaline deposits in anterior stroma. Intervening

stroma is clear. The condition developing in first

Fuchs dystrophy is frequently seen as a slowly

progressive bilateral condition affecting females more

decade of life is slowly progressive and usually

than males, usually between fifth and seventh decade

asymptomatic. Occasionally visual acuity may be

of life. Primary open angle glaucoma is its common

severely impaired, requiring keratoplasty.

association.

Macular dystrophy (Groenouw type-II)

Clinical features can be divided into following four

It is an autosomal recessive dystrophy characterised

stages:

by appearance of dense grey opacity in the central

1. Stage of cornea guttata. It is characterised by the

cornea. The condition results due to accumulation of

presence of Hassal-Henle type of excrescenses in

mucopolysaccharides owing to a local enzyme

the central part of cornea. A gradual increase of

deficiency. It occurs in childhood (5 to 10 years) and

central guttae with peripheral spread and confluence

leads to marked defective vision in early life, which

gives rise to the so called 'beaten-metal'

usually requires penetrating keratoplasty.

appearance. This stage is asymptomatic.

DISEASES OF THE CORNEA

119

2. Oedematous stage or stage of endothelial

ECTATIC CONDITIONS OF CORNEA

decompensation is characterised by the

occurrence of early stromal oedema and epithelial

KERATOCONUS

dystrophy. Patients complains of blurring vision.

Keratoconus (conical cornea) (Fig. 5.18) is a non-

3. Stage of bullous keratopathy. This stage follows

inflammatory bilateral (85%) ectatic condition of

long-standing stromal oedema and is characterised

cornea in its axial part. It usually starts at puberty

by marked epithelial oedema with formation of

and progresses slowly.

bullae, which when rupture cause pain, discomfort

Etiopathogenesis. It is still not clear. Various theories

and irritation with associated decreased visual

proposed so far label it as developmental condition,

acuity.

degenerative condition, hereditary dystrophy and

endocrine anomaly. Essential pathological changes

4. Stage of scarring. In this stage epithelial bullae

are thinning and ectasia which occur as a result of

are replaced by scar tissue and cornea becomes

defective synthesis of mucopolysaccharide and

opaque and vascularized. The condition may

collagen tissue.

sometimes be complicated by occurrence of

Clinical features. Symptoms. Patient presents with a

secondary infection or glaucoma.

defective vision due to progressive myopia and

irregular astigmatism, which does not improve fully

Treatment is as follows :

despite full correction with glasses.

1. In early oedematous stage use of

5 percent

Signs. Following signs may be elicited:

sodium chloride (hypertonic saline) may be of

1. Window reflex is distorted.

some use.

2. Placido disc examination shows irregularity of

the circles (Fig. 5.18B).

2. Bandage soft contact lenses provide some relief

3. Keratometry depicts extreme malalignment of

from disturbing symptoms in bullous keratopathy

mires.

stage.

4. Photokeratoscopy reveals distortion of circles.

3. Penetrating keratoplasty is the treatment of

5. Slit lamp examination (Fig. 5.18C) may show

choice when the visual acuity is reduced markedly.

thinning and ectasia of central cornea, opacity at

the apex and Fleischer's ring at the base of cone,

folds in Descemet's and Bowman's membranes.

Posterior polymorphous dystrophy

Very fine, vertical, deep stromal striae (Vogt lines)

It is a dominantly inherited dystrophy of endothelium

which disappear with external pressure on the

and Descemet's membrane. It is characterised by

globe are peculiar feature.

lesions with variable appearance, such as vesicles,

6. On retinoscopy a yawning reflex (scissor reflex)

curvilinear lines or geographical opacities at the level

and high oblique or irregular astigmatism is

of Descemet's membrane. The condition is very slowly

obtained.

progressive and thus usually asymptomatic. Corneal

7. On distant direct ophthalmoscopy an annular

oedema sometimes may occur, requiring keratoplasty.

dark shadow (due to total internal reflection of

light) is seen which separates the central and

Rarely it may be complicated by secondary glaucoma.

peripheral areas of cornea (oil droplet reflex).

8. Munson's sign, i.e. localised bulging of lower lid

Congenital hereditary endothelial dystrophy

when patient looks down is positive in late stages.

(CHED)

Morphological classification. Depending upon the

This is a rare dystrophy associated with scanty or

size and shape of the cone. the keratoconus is of

absent endothelial cells and thickened Descemet's

three types:

membrane. The basic endothelial deficiency results

Nipple cone has a small size (<5mm) and steep

in diffuse milky or ground glass opacification and

curvature.

marked thickening of corneal stroma. It may be

Oval cone is larger (5-6 mm) and ellipsoid in

inherited both dominantly and recessively.

shape.

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Comprehensive OPHTHALMOLOGY

Systemic conditions e.g., Marfan's sysndrome,

atopy, Down's syndrome, Ehlers-Danlos

syndrome, osteogenesis imperfecta and mitral

valve prolapse.

Treatment. Falling vision may not be corrected by

glasses due to irregular astigmatism.

Contact lenses

(rigid gas permiable) usually

improve the vision in early cases.

In later stages penetrating keratoplasty may be

required.

Intacs, the intracorneal ring segments, are

reported to be useful in early cases.

KERATOGLOBUS

It is a familial and hereditary bilateral congenital

disorder characterised by thinning and hemispherical

protrusion of the entire cornea. It is non-progressive

and inherited as an autosomal recessive trait. It must

be differentiated from congenital buphthalmos, where

increased corneal size is associated with raised

intraocular pressure, angle anomaly, and/or cupping

of optic disc.

KERATOCONUS POSTERIOR

In this extremely rare condition there is slight cone-

like bulging of the posterior surface of the cornea. It

is non-progressive.

ABNORMALITIES OF CORNEAL

TRANSPARENCY

Normal cornea is a transparent structure. Any

Fig. 5.18. Keratoconus showing: A, configuration of

cone-shaped cornea; B, irregular circles on Placido disc

condition which upsets its anatomy or physiology

examination; C, clinical photograph.

causes loss of its transparency to some degree.

Common causes of loss of corneal transparency are:

Globus cone is very large (>6 mm) and globe like.

Corneal oedema

Complications. Keratoconus may be complicated by

Drying of cornea

development of acute hydrops due to rupture of

Depositions on cornea

Descemet's membrane. The condition is characterised

Inflammations of cornea

by sudden development of corneal oedema associated

Corneal degenerations

with marked defective vision, pain, photophobia and

Dystrophies of cornea

lacrimation.

Vascularization of cornea

Associations. Keratoconus may be associated with :

Scarring of cornea (corneal opacities)

Ocular conditions e.g. ectopia lentis, congenital

Most of the conditions responsible for decreased

cataract, aniridia, retinitis pigmentosa, and vernal

transparency of cornea have been described earlier.

keratoconjunctivitis (VKC).

However, some important symptomatic conditions of

DISEASES OF THE CORNEA

121

the cornea such as corneal oedema, corneal opacity

i. Hypertonic agents e.g.,

5 percent sodium

and vascularization of cornea are described here.

chloride drops or ointments or anhydrous

glycerine may provide sufficient dehydrating

CORNEAL OEDEMA

effect.

The water content of normal cornea is 78 percent. It

ii. Hot forced air from hair dryer may be useful.

is kept constant by a balance of factors which draw

3. Therapeutic soft contact lenses may be used to

water in the cornea (e.g., intraocular pressure and

get relief from discomfort of bullous keratopathy.

swelling pressure of the stromal matrix = 60 mm of

4. Penetrating keratoplasty is required for long-

Hg) and the factors which draw water out of cornea

standing cases of corneal oedema, non-respon-

(viz. the active pumping action of corneal

sive to conservative therapy.

endothelium, and the mechanical barrier action of

CORNEAL OPACITIES

epithelium and endothelium).

Disturbance of any of the above factors leads to

The word 'corneal opacification' literally means loss

corneal oedema, wherein its hydration becomes above

of normal transparency of cornea, which can occur in

78 percent, central thickness increases and

many conditions. Therefore, the term 'corneal

transparency reduces.

opacity' is used particularly for the loss of

transparency of cornea due to scarring.

Causes of corneal oedema

1. Raised intraocular pressure

Causes

2. Endothelial damage

1. Congenital opacities may occur as developmental

i. Due to injuries, such as birth trauma (forceps

anomalies or following birth trauma.

delivery), surgical trauma during intraocular

2. Healed corneal wounds.

operation, contusion injuries and penetrating

3. Healed corneal ulcers.

injuries.

Clinical features

ii. Endothelial damage associated with corneal

dystrophies such as, Fuchs dystrophy,

A corneal opacity may produce loss of vision (when

dense opacity covers the pupillary area) or blurred

congenital hereditary endothelial dystrophy

vision (due to astigmatic effect).

and posterior polymorphous dystrophy.

iii. Endothelial damage secondary to inflammations

Types of corneal opacity

such as uveitis, endophthalmitis and corneal

Depending on the density, corneal opacity is graded

graft infection.

as nebula, macula and leucoma.

3. Epithelial damage due to :

1. Nebular corneal opacity. It is a faint opacity

i. mechanical injuries

which results due to superficial scars involving

ii. chemical burns

Bowman's layer and superficial stroma (Figs. 5.19A

iii. radiational injuries

and 5.20A). A thin, diffuse nebula covering the

pupillary area interferes more with vision than the

Clinical features

localised leucoma away from pupillary area.

Initially there occurs stromal haze with reduced vision.

Further, the nebula produces more discomfort to

In long-standing cases with chronic endothelial

patient due to blurred image owing to irregular

failure (e.g., in Fuch's dystrophy) there occurs

astigmatism than the leucoma which completely

permanent oedema with epithelial vesicles and bullae

cuts off the light rays.

formation (bullous keratopathy). This is associated

2. Macular corneal opacity. It is a semi-dense

with marked loss of vision, pain, discomfort and

opacity produced when scarring involves about

photophobia, due to periodic rupture of bullae.

half the corneal stroma (Figs. 5.19B and 5.20B).

Treatment

3. Leucomatous corneal opacity (leucoma simplex).

1. Treat the cause wherever possible, e.g., raised

It is a dense white opacity which results due to

IOP and ocular inflammations.

scarring of more than half of the stroma (Figs.

2. Dehydration of cornea may be tried by use of:

5.19C and 5.20C).

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Comprehensive OPHTHALMOLOGY

4. Adherent leucoma: It results when healing occurs

4. Cosmetic coloured contact lens gives very good

after perforation of cornea with incarceration of

cosmetic appearance in an eye with ugly scar

iris (Figs. 5.19D and 5.20D).

having no potential for vision. Presently, this is

5. Corneal facet. Sometimes the corneal surface is

considered the best option, even over and above

depressed at the site of healing

(due to less

the tatooing for cosmetic purpose.

fibrous tissue); such a scar is called facet.

5. Tattooing of scar. It was performed for cosmetic

6. Kerectasia. In this condition corneal curvature is

purposes in the past. It is suitable only for firm scars

increased at the site of opacity

(bulge due to

in a quiet eye without useful vision. For tattooing

weak scar).

Indian black ink, gold or platinum may be used. To

7. Anterior staphyloma. An ectasia of psuedocornea

perform tattooing, first of all, the epithelium

(the scar formed from organised exudates and

covering the opacity is removed under topical

fibrous tissue covered with epithelium) which

anaesthesia (2 percent or 4 percent xylocaine). Then

results after total sloughing of cornea, with iris

a piece of blotting paper of the same size and shape,

plastered behind it is called anterior staphyloma

soaked in 4 percent gold chloride (for brown colour)

(Figs. 5.21 A and B).

or 2 percent platinum chloride (for dark colour) is

applied over it. After 2-3 minutes the piece of filter

Secondary changes in corneal opacity which may

paper is removed and a few drops of freshly

be seen in long-standing cases include: hyaline

prepared hydrazine hydrate (2 percent) solution are

degeneration, calcareous degeneration, pigmentation

poured over it. Lastly, eye is irrigated with normal

and atheromatous ulceration.

saline and patched after instilling antibiotic and

Treatment

atropine eye ointment. Epithelium grows over the

1. Optical iridectomy. It may be performed in cases

pigmented area.

with central macular or leucomatous corneal

VASCULARIZATION OF CORNEA

opacities, provided vision improves with pupillary

dilatation.

Normal cornea is avascular except for small capillary

2. Keratoplasty provides good visual results in

loops which are present in the periphery for about 1

uncomplicated cases with corneal opacities, where

mm. In pathological states, it can be invaded by

optical iridectomy is not of much use.

vessels as a defence mechanism against the disease

3. Phototherapeutic keratectomy (PTK) performed

or injury. However, vascularization interferes with

with excimer laser is useful in superficial (nebular)

corneal transparency and occasionally may be a

corneal opacities.

source of irritation.

Fig. 5.19. Diagramatic depiction of corneal opacity: A, nebular; B, macular; C, leucomatous; D, adherent leucoma.

124

Comprehensive OPHTHALMOLOGY

Pathogenesis

Pathogenesis of corneal vascularization is still not

clear. It is presumed that mechanical and chemical

factors play a role.

Vascularization is normally prevented by the

compactness of corneal tissue. Probably due to some

vasoformative stimulus (chemical factor) released

during pathological states, there occurs proliferation

of vessels which invade from the limbus; when

compactness of corneal tissue is loosened

(mechanical factor) due to oedema (which may be

traumatic, inflammatory, nutritional, allergic or

idiopathic in nature).

Clinico-etiological features

Clinically, corneal vascularization may be superficial

or deep.

1. Superficial corneal vascularization. In it vessels

are arranged usually in an arborising pattern, present

below the epithelial layer and their continuity can be

traced with the conjunctival vessels (Fig. 5.22A).

Fig. 5.22. Corneal vascularization : A, superficial

B, terminal loop type C, brush type D, umbel type

Common causes of superficial corneal vascularization

are: trachoma, phlyctenular kerato-conjunctivitis,

superficial corneal ulcers and rosacea keratitis.

capillaries. Application of irradiation is more useful

Pannus. When extensive superficial vascularization

in superficial than the deep vascularization. Surgical

is associated with white cuff of cellular infiltration, it

treatment in the form of peritomy may be employed

is termed as pannus. In progressive pannus, corneal

for superficial vascularization.

infiltration is ahead of vessels while in regressive

pannus it lags behind.

KERATOPLASTY

2. Deep vascularization. In it the vessels are generally

Keratoplasty, also called corneal grafting or corneal

derived from anterior ciliary arteries and lie in the

transplantation, is an operation in which the patient's

corneal stroma. These vessels are usually straight,

diseased cornea is replaced by the donor's healthy

not anastomosing and their continuity cannot be

clear cornea.

traced beyond the limbus. Deep vessels may be

arranged as terminal loops (Fig. 5.22B), brush (Fig.

Types

5.22C), parasol, umbel (Fig. 5.22 D), network or

1. Penetrating keratoplasty (full-thickness grafting)

interstitial arcade.

2. Lamellar keratoplasty (partial-thickness grafting).

Common causes of deep vascularization are:

interstitial keratitis, disciform keratitis, deep corneal

Indications

ulcer, chemical burns and sclerosing keratitis and

1. Optical, i.e., to improve vision. Important indications

grafts.

are: corneal opacity, bullous keratopathy, corneal

dystrophies, advanced keratoconus.

Treatment

2. Therapeutic, i.e., to replace inflamed cornea not

Treatment of corneal vascularization is usually

responding to conventional therapy.

unsatisfactory. Vascularization may be prevented by

timely and adequate treatment of the causative

3. Tectonic graft, i.e., to restore integrity of eyeball

conditions. Corticosteroids may have vasoconstri-

e.g. after corneal perforation and in marked corneal

ctive and suppressive effect on permeability of

thinning.

DISEASES OF THE CORNEA

125

4. Cosmetic, i.e., to improve the appearance of the eye.

Surgical technique

1. Excision of donor corneal button (Fig. 5.23A).

Donor tissue

The donor corneal button should be cut 0.25 mm

The donor eye should be removed as early as

larger than the recipient, taking care not to damage

possible (within 6 hours of death). It should be stored

the endothelium.

under sterile conditions.

2. Excision of recipient corneal button. With the

Evaluation of donor cornea. Biomicroscopic

help of a corneal trephine (7.5 mm to 8 mm in size)

examination of the whole globe, before processing

a partial thickness incision is made in the host

the tissue for media stroage, is very important. The

cornea (Fig. 5.23B). Then, anterior chamber is

donor corneal tissue is graded into excellent, very

entered with the help of a razor blade knife and

good, good, fair, and poor depending upon the

excision is completed using corneo-scleral scissors

condition of corneal epithelium, stroma, Descemet's

(Fig. 5.23C).

membrane and endothelium (Table 5.1).

3. Suturing of corneal graft into the host bed (Fig.

Methods of corneal preservation

5.23D) is done with either continuous (Fig. 5.23E)

or interrupted (Fig. 5.23F) 10-0 nylon sutures.

1. Short-term storage (up to 48 hours). The whole

globe is preserved at 4^oC in a moist chamber.

Complications

2. Intermediate storage (up to 2 weeks) of donor

1. Early complications. These include flat anterior

cornea can be done in McCarey-Kaufman (MK)

chamber, iris prolapse, infection, secondary

medium and various chondroitin sulfate enriched

glaucoma, epithelial defects and primary graft

media such as optisol medium.

failure.

3. Long-term storage up to 35 days is done by

2. Late complications. These include graft rejection,

organ culture method.

recurrence of disease and astigmatism.

Table 5.1 : Grading of donor cornea on slit-lamp biomicroscopic examination

Grade of donor corneal tissue

Parameter

Grade I

Grade II

Grade III

Grade IV

Grade V

(Excellent)

(Very good)

(Good)

(Fair)

(Poor)

Epithelial defects None

Slight epithelial

Obvious moderate

and haze

haze or defects

epithelial defects

Corneal stromal

Crystal clear

Clear

Slight

Moderate

Marked

clarity

cloudiness

Arcus senilis

None

Slight

Moderate

Heavy

Very heavy

(<2.5mm)

(>2.5mm-4mm)

(>4 mm)

Descemet's

Few shallow

Numerous shallow

Numerous deep Marked deep

membrane

folds

Endothelium

No defect

Few vacuolated

Moderate

Marked

cells

guttate

Diseases of

CHAPTER

the Sclera

APPLIED ANATOMY

BLUE SCLERA

INFLAMMATIONS OF THE SCLERA

STAPHYLOMAS

Episcleritis

Intercalary

Scleritis

Ciliary

- Anterior

Equatorial

- Posterior

Posterior

Microscopic structure. Histologically, sclera consists

APPLIED ANATOMY

of following three layers:

1. Episcleral tissue. It is a thin, dense vascularised

Sclera forms the posterior five-sixth opaque part of

layer of connective tissue which covers the sclera

the external fibrous tunic of the eyeball. Its whole

proper. Fine fibroblasts, macrophages and

outer surface is covered by Tenon's capsule. In the

lymphocytes are also present in this layer.

anterior part it is also covered by bulbar conjunctiva.

2. Sclera proper. It is an avascular structure which

Its inner surface lies in contact with choroid with a

consists of dense bundles of collagen fibres. The

potential suprachoroidal space in between. In its

bands of collagen tissue cross each other in all

anterior most part near the limbus there is a furrow

directions.

which encloses the canal of Schlemm.

Thickness of sclera varies considerably in different

individuals and with the age of the person. It is

generally thinner in children than the adults and in

females than the males. Sclera is thickest posteriorly

(1mm) and gradually becomes thin when traced

anteriorly. It is thinnest at the insertion of extraocular

muscles (0.3 mm). Lamina cribrosa is a sieve-like sclera

from which fibres of optic nerve pass.

Apertures. Sclera is pierced by three sets of apertures

(Fig. 6.1).

1. Posterior apertures are situated around the optic

nerve and transmit long and short ciliary nerves

and vessels.

2. Middle apertures (four in number) are situated

slightly posterior to the equator; through these

pass the four vortex veins (vena verticosae).

Fig. 6.1. Apertures in the sclera. (posterior view) for:

3. Anterior apertures are situated 3 to 4 mm away

SCN, short ciliary nerve; SPCA, short posterior ciliary

from the limbus. Anterior ciliary vessels pass

artery; LPCA, long posterior ciliary artery; VC, vena

through these apertures.

verticosa

128

Comprehensive OPHTHALMOLOGY

3. Lamina fusca. It is the innermost part of sclera

situated 2-3 mm away from the limbus (Fig. 6.2B).

which blends with suprachoroidal and supraciliary

The nodule is firm, tender and the overlying

laminae of the uveal tract. It is brownish in colour

conjunctiva moves freely.

owing to the presence of pigmented cells.

Clinical course. Episcleritis runs a limited course of

Nerve supply. Sclera is supplied by branches from

10 days to 3 weeks and resolves spontaneously.

the long ciliary nerves which pierce it 2-4 mm from

However, recurrences are common and tend to occur

the limbus to form a plexus.

in bouts. Rarely, a fleeting type of disease (episcleritis

periodica) may occur.

Differential diagnosis

INFLAMMATIONS OF THE SCLERA

Occasionally episcleritis may be confused with

inflamed pinguecula, swelling and congestion due to

EPISCLERITIS

foreign body lodged in bulbar conjunctiva and very

Episcleritis is benign recurrent inflammation of the

rarely with scleritis.

episclera, involving the overlying Tenon's capsule

but not the underlying sclera. It typically affects

young adults, being twice as common in women than

men.

Etiology

Exact etiology is not known.

It is found in association with gout, rosacea and

psoriasis.

It has also been considered a hypersensitivity

reaction to endogenous tubercular or

streptococcal toxins.

Pathology

Histologically, there occurs localised lymphocytic

infiltration of episcleral tissue associated with oedema

and congestion of overlying Tenon's capsule and

conjunctiva.

Clinical picture

Symptoms. Episcleritis is characterised by redness,

mild ocular discomfort described as gritty, burning or

foreign body sensation. Many a time it may not be

accompanied by any discomfort at all. Rarely, mild

photophobia and lacrimation may occur.

Signs. On examination two clinical types of

episcleritis, diffuse (simple) and nodular may be

recognised. Episclera is seen acutely inflamed in the

involved area.

In diffuse episcleritis, although whole eye may

be involved to some extent, the maximum

inflammation is confined to one or two quadrants

(Fig. 6.2A).

In nodular episcleritis, a pink or purple flat

nodule surrounded by injection is seen, usually

Fig. 6.2. Episcleritis: A, Diffuse; B, Nodular.

DISEASES OF THE SCLERA

129

Treatment

6. Surgically induced scleritis follows ocular

1. Topical corticosteroid eyedrops instilled

2-3

surgery. It occurs within 6 month postoperatively.

hourly, render the eye more comfortable and

Exact mechanism not known, may be precipitation

resolve the episcleritis within a few days.

of underlying systemic cause.

2. Cold compresses applied to the closed lids may

7. Idiopathic. In many cases cause of scleritis is

unknown.

offer symptomatic relief from ocular discomfort.

3. Systemic non-steroidal anti-inflammatory drugs

Pathology

(NSAIDs) such as flurbiprofen (300 mg OD),

Histopathological changes are that of a chronic

indomethacin

(25 mg three times a day), or

granulomatous disorder characterised by fibrinoid

oxyphenbutazone may be required in recurrent

necrosis, destruction of collagen together with

cases.

infiltration by polymorphonuclear cells, lymphocytes,

plasma cells and macrophages. The granuloma is

SCLERITIS

surrounded by multinucleated epitheloid giant cells

Scleritis refers to a chronic inflammation of the sclera

and old and new vessels, some of which may show

proper. It is a comparatively serious disease which

evidence of vasculitis.

may cause visual impairment and even loss of the

Classification

eye if treated inadequately. Fortunately, its incidence

is much less than that of episcleritis. It usually occurs

It can be classified as follows:

in elderly patients (40-70 years) involving females

I. Anterior scleritis (98%)

more than the males.

1. Non-necrotizing scleritis (85%)

(a) Diffuse

Etiology

(b) Nodular

It is found in association with multiple conditions

2. Necrotizing scleritis (13%)

which are as follows:

(a) with inflammation

1. Autoimmune collagen disorders, especially

(b) without inflammation

(scleromalacia

perforans)

rheumatoid arthritis, is the most common

II. Posterior scleritis (2%)

association. Overall about 5% cases of scleritis

are associated with some connective tissue

Clinical features

disease. About 0.5 percent of patients (1 in 200)

Symptoms. Patients complain of moderate to severe

suffering from seropositive rheumatoid arthritis

pain which is deep and boring in character and often

develop scleritis. Other associated collagen

wakes the patient early in the morning . Ocular pain

disorders are Wegener's granulomatosis,

radiates to the jaw and temple. It is associated with

polyarteritis nodosa

(PAN), systemic lupus

localised or diffuse redness, mild to severe

erythematosus (SLE) and ankylosing spondylitis.

photophobia and lacrimation. Occasionally there

2. Metabolic disorders like gout and thyrotoxicosis

occurs diminution of vision.

have also been reported to be associated with

scleritis.

Signs. The salient features of different clinical types

of scleritis are as follows:

3. Some infections, particularly herpes zoster

ophthalmicus, chronic staphylococcal and

1. Non-necrotizing anterior diffuse scleritis. It is the

streptococcal infection have also been known to

commonest variety, characterised by widespread

cause scleritis.

inflammation involving a quadrant or more of the

4. Granulomatous diseases like tuberculosis,

anterior sclera. The involved area is raised and salmon

syphilis, sarcoidosis, leprosy can also cause

pink to purple in colour (Fig. 6.3).

scleritis.

2. Non-necrotizing anterior nodular scleritis. It is

5. Miscellaneous conditions like irradiation, chemical

characterised by one or two hard, purplish elevated

burns, Vogt-Koyanagi-Harada syndrome, Behcet's

scleral nodules, usually situated near the limbus (Fig.

disease and rosacea are also implicated in the

6.4). Sometimes, the nodules are arranged in a ring

etiology.

around the limbus (annular scleritis).

130

Comprehensive OPHTHALMOLOGY

3. Anterior necrotizing scleritis with inflammation.

It is an acute severe form of scleritis characterised by

intense localised inflammation associated with areas

of infarction due to vasculitis (Fig. 6.5). The affected

necrosed area is thinned out and sclera becomes

transparent and ectatic with uveal tissue shining

through it. It is usually associated with anterior

uveitis.

4. Anterior necrotizing scleritis without

inflammation (scleromalacia perforans). This specific

entity typically occurs in elderly females usually

suffering from long-standing rheumatoid arthritis. It

is characterised by development of yellowish patch

Fig. 6.3. Non-necrotizing anterior diffuse scleritis.

of melting sclera (due to obliteration of arterial supply);

which often together with the overlying episclera and

conjunctiva completely separates from the

surrounding normal sclera. This sequestrum of sclera

becomes dead white in colour, which eventually

absorbs leaving behind it a large punched out area of

thin sclera through which the uveal tissue shines

(Fig. 6.6). Spontaneous perforation is extremely rare.

5. Posterior scleritis. It is an inflammation involving

the sclera behind the equator. The condition is

frequently misdiagnosed. It is characterised by

features of associated inflammation of adjacent

structures, which include: exudative retinal

detachment, macular oedema, proptosis and limitation

of ocular movements.

Fig. 6.4. Non-necrotizing anterior nodular scleritis.

Complications

These are quite common with necrotizing scleritis and

include sclerosing keratitis, keratolysis, complicated

cataract and secondary glaucoma.

Fig. 6.6. Anterior necrotizing scleritis without inflammation

Fig. 6.5. Anterior necrotizing scleritis with inflammation.

(Scleromalacia perforans).

DISEASES OF THE SCLERA

131

Investigations

to thinning (Fig. 6.7). It is a typical association of

Following laboratory studies may be helpful in

osteogenesis imperfecta. Its other causes are

identifying associated systemic diseases or in

Marfan's syndrome, Ehlers-Danlos syndrome,

establishing the nature of immunologic reaction:

pseudoxanthoma elasticum, buphthalmos, high

1. TLC, DLC and ESR

myopia and healed scleritis.

2. Serum levels of complement

(C3), immune

complexes, rheumatoid factor, antinuclear

STAPHYLOMAS

antibodies and L.E cells for an immunological

survey.

Staphyloma refers to a localised bulging of weak and

3. FTA - ABS, VDRL for syphilis.

thin outer tunic of the eyeball (cornea or sclera), lined

4. Serum uric acid for gout.

by uveal tissue which shines through the thinned

5. Urine analysis.

out fibrous coat.

6. Mantoux test.

Types

7. X-rays of chest, paranasal sinuses, sacroiliac

Anatomically it can be divided into anterior,

joint and orbit to rule out foreign body especially

intercalary, ciliary, equatorial and posterior

in patients with nodular scleritis.

staphyloma (Fig. 6.8).

Treatment

(A) Non-necrotising scleritis. It is treated by topical

steroid eyedrops and systemic indomethacin 100 mg

daily for a day and then 75 mg daily until inflammation

resolves.

(B) Necrotising scleritis. It is treated by topical

steroids and heavy doses of oral steroids tapered

slowly. In non-responsive cases, immuno-suppressive

agents like methotrexate or cyclophos-phamide may

be required. Subconjunctival steroids are

contraindicated because they may lead to scleral

thinning and perforation.

BLUE SCLERA

It is an asymptomatic condition characterised by

marked, generalised blue discolouration of sclera due

Fig. 6.8. Staphylomas (diagramatic depiction) :

A, intercalary; B, ciliary; C, equatorial; D, posterior.

1. Anterior staphyloma. (see page 122)

2. Intercalary staphyloma. It is the name given to

the localised bulge in limbal area lined by root of iris

(Figs. 6.8A and 6.9). It results due to ectasia of weak

scar tissue formed at the limbus, following healing of

a perforating injury or a peripheral corneal ulcer. There

Fig. 6.7. Blue sclera.

may be associated secondary angle closure glaucoma,

132

Comprehensive OPHTHALMOLOGY

which may cause progression of bulge if not treated.

Defective vision occurs due to marked corneal

astigmatism.

Fig. 6.9. Intercalary staphyloma.

Fig. 6.10. Ciliary staphyloma.

Treatment consists of localised staphylectomy under

excavated with retinal vessels dipping in it (just like

heavy doses of oral steroids.

marked cupping of optic disc in glaucoma) (Fig. 6.11).

3. Ciliary staphyloma. As the name implies, it is the

Its floor is focussed with minus number lenses in

bulge of weak sclera lined by ciliary body. It occurs

ophthalmo-scope as compared to its margin.

about 2-3 mm away from the limbus (Figs. 6.8B and

6.10). Its common causes are thinning of sclera

following perforating injury, scleritis and absolute

glaucoma.

4. Equatorial staphyloma. It results due to bulge of

sclera lined by the choroid in the equatorial region

(Fig. 6.8C). Its causes are scleritis and degeneration

of sclera in pathological myopia. It occurs more

commonly at the regions of sclera which are

perforated by vortex veins.

5. Posterior staphyloma. It refers to bulge of weak

sclera lined by the choroid behind the equator (Fig.

6.8D). Here again the common causes are pathological

myopia, posterior scleritis and perforating injuries. It

Fig. 6.11. Fundus photograph showing excavation of

is diagnosed on ophthalmoscopy. The area is

retinal tissue in posterior staphyloma.

Diseases of the

CHAPTER

Uveal Tract

APPLIED ANATOMY

Specific clinico-etiological types

Iris

of uveitis

Ciliary body

DEGENERATIVE CONDITIONS

Choroid

of iris

CONGENITAL ANOMALIES

of choroid

INFLAMMATIONS (UVEITIS)

General considerations

TUMOURS

Anterior uveitis

of choroid

Posterior uveitis

of ciliary body

Endophthalmitis and Panophthalmitis

of iris

iris is missing. Crypts are arranged in two rows

APPLIED ANATOMY

—the peripheral present near the iris root and the

central present near the collarette.

Uveal tissue constitutes the middle vascular coat of

2. Pupillary zone. This part of the iris lies between

the eyeball. From anterior to posterior it can be

the collarette and pigmented pupillary frill and is

divided into three parts, namely, iris, ciliary body

relatively smooth and flat.

and choroid. However, the entire uveal tract is

developmentally, structurally and functionally one

Microscopic structure (Fig. 7.2) . The iris consists of

indivisible structure.

four layers which from anterior to posterior are :

THE IRIS

Iris is the anterior most part of the uveal tract. It is a

thin circular disc corresponding to the diaphragm of

a camera. In its centre is an aperture of about 4-mm

diameter called pupil which regulates the amount of

light reaching the retina. At the periphery, the iris is

attached to the middle of anterior surface of the ciliary

body. It divides the space between the cornea and

lens into anterior and posterior chambers.

Macroscopic appearance. Anterior surface of the iris

can be divided into a ciliary zone and a pupillary zone

by a zigzag line called collarette (Fig. 7.1).

1. Ciliary zone. It presents series of radial streaks

due to underlying radial blood vessels and crypts

Fig. 7.1. Macroscopic appearance of anterior

which are depressions where superficial layer of

surface of iris.

134

Comprehensive OPHTHALMOLOGY

Anterior limiting layer. It is the anterior most

and ciliary body. This layer gives rise to the

condensed part of the stroma. It consists of

dilator pupillae muscle.

melanocytes and fibroblasts. Previously this layer

4. The posterior pigmented epithelial layer. It is

was called endothelial layer of iris which was a

anterior continuation of the non-pigmented

misnomer. This layer is deficient in the areas of

epithelium of ciliary body. At the pupillary margin

crypts. The definitive colour of the iris depends

it forms the pigmented frill and becomes

on this layer. In blue iris this layer is thin and

continuous with the anterior pigmented epithelial

contains few pigment cells. While in brown iris it

layer.

is thick and densely pigmented.

CILIARY BODY

Iris stroma. It consists of loosely arranged

Ciliary body is forward continuation of the choroid at

collagenous network in which are embedded the

ora serrata. In cut-section, it is triangular in shape.

sphincter pupillae muscle, dilator pupillae muscle,

The anterior side of the triangle forms the part of the

vessels, nerves, pigment cells and other cells

angle of anterior and posterior chambers. In its middle

which include lymphocytes, fibroblasts,

the iris is attached. The outer side of the triangle lies

macrophages and mast cells.

against the sclera with a suprachoroidal space in

The sphincter pupillae muscle forms one

between. The inner side of the triangle is divided into

millimetre broad circular band in the pupillary

two parts. The anterior part (about 2 mm) having

part of the iris. It is supplied by parasympathetic

finger-like ciliary processes is called pars plicata and

fibres through third nerve. It constricts the

the posterior smooth part (about 4 mm) is called pars

pupil.

plana (Fig. 7.2).

The dilator pupillae muscle lies in the

Microscopic structure (Fig. 7.2). From without

posterior part of stroma of the ciliary zone of

inwards ciliary body consists of following five layers:

iris. Its myofilaments are located in the outer

1. Supraciliary lamina. It is the outermost

part of the cells of anterior pigment epithelial

condensed part of the stroma and consists of

layer. It is supplied by cervical sympathetic

pigmented collagen fibres. Posteriorly, it is the

nerves and dilates the pupil.

continuation of suprachoroidal lamina and

Anterior epithelial layer. It is anterior

anteriorly it becomes continuous with the anterior

continuation of the pigment epithelium of retina

limiting membrane of iris.

Fig. 7.2. Microscopic structure of the iris and ciliary body.

DISEASES OF THE UVEAL TRACT

135

Stroma of the ciliary body. It consists of

connective tissue of collagen and fibroblasts.

Embedded in the stroma are ciliary muscle, vessels,

nerves, pigment and other cells.

Ciliary muscle occupies most of the outer part of

ciliary body. In cut section it is triangular in

shape. It is a non-striated muscle having three

parts:

(i) the longitudinal or meridional fibres

which help in aqueous outflow; (ii) the circular

fibres which help in accommodation; and (iii) the

Fig. 7.3. Microscopic structure of the choroid.

radial or oblique fibres act in the same way as the

longitudinal fibres. Ciliary muscle is supplied by

Suprachoroidal lamina. It is a thin membrane of

parasympathetic fibres through the short ciliary

condensed collagen fibres, melanocytes and

nerves.

fibroblasts. It is continuous anteriorly with the

Layer of pigmented epithelium. It is the forward

supraciliary lamina. The potential space between

continuation of the retinal pigment epithelium.

this membrane and sclera is called suprachoroidal

Anteriorly it is continuous with the anterior

space which contains long and short posterior

pigmented epithelium of the iris.

ciliary arteries and nerves.

Layer of non-pigmented epithelium. It consists

Stroma of the choroid. It consists of loose

mainly of low columnar or cuboidal cells, and is

collagenous tissue with some elastic and reticulum

the forward continuation of the sensory retina. It

fibres. It also contains pigment cells and plasma

cells. Its main bulk is formed by vessels which

continues anteriorly as the posterior

(internal)

are arranged in three layers. From without inwards

pigmented epithelium of the iris.

these are: (i) layer of large vessels (Haller’s layer),

Internal limiting membrane. It is the forward

(ii) layer of medium vessels (Sattler’s layer) and

continuation of the internal limiting membrane of

(iii) layer of choriocapillaris which nourishes the

the retina. It lines the non-pigmented epithelial

outer layers of the retina.

layers.

Basal lamina. It is also called Bruch’s membrane

Ciliary processes. These are finger-like projections

and lines the layer of choriocapillaris. It lies in

from the pars plicata part of the ciliary body. These

approximation with pigment epithelium of the

are about 70-80 in number. Each process is about

retina.

2-mm long and 0.5-mm in diameter. These are white in

colour.

Blood supply of the uveal tract

Structure. Each process is lined by two layers of

Arterial supply. The uveal tract is supplied by three

epithelial cells. The core of the ciliary process contains

sets of arteries (Fig. 7.4):

blood vessels and loose connective tissue. These

1. Short posterior ciliary arteries. These arise as

processes are the site of aqueous production.

two trunks from the ophthalmic artery; each trunk

Functions of ciliary body. (i) Formation of aqueous

divides into

10-20 branches which pierce the

humour. (ii) Ciliary muscles help in accommodation.

sclera around the optic nerve and supply the

choroid in a segmental manner.

CHOROID

2. Long posterior ciliary arteries. These are two in

Choroid is the posterior most part of the vascular

number, nasal and temporal. These pierce the

coat of the eyeball. It extends from the optic disc to

sclera obliquely on medial and lateral side of the

ora serrata. Its inner surface is smooth, brown and

optic nerve and run forward in the suprachoroidal

lies in contact with pigment epithelium of the retina.

space to reach the ciliary muscle, without giving

The outer surface is rough and lies in contact with

any branch. At the anterior end of ciliary muscle

the sclera.

these anastomose with each other and with the

Microscopic structure (Fig. 7.3). From without

anterior ciliary arteries; and gives branches which

inwards choroid consists of following three layers:

supply the ciliary body.

136

Comprehensive OPHTHALMOLOGY

Fig. 7.4. Blood supply of the uveal tract.

3. Anterior ciliary arteries. These are derived from

(one branch for each process). Similarly, many

the muscular branches of ophthalmic artery. These

branches from this major arterial circle run radially

are 7 in number; 2 each from arteries of superior

through the iris towards pupillary margin, where

rectus, inferior rectus, and medial rectus muscle

they anastomose with each other to form circulus

and one from that of lateral rectus muscle. These

arteriosus minor.

arteries pass anteriorly in the episclera, give

Venous drainage. A series of small veins which drain

branches to sclera, limbus and conjunctiva; and

blood from the iris, ciliary body and choroid join to

ultimately pierce the sclera near the limbus to

form the vortex veins. The vortex veins are four in

enter the ciliary muscle; where they anastomose

number-superior temporal, inferior temporal, superior

with the two long posterior ciliary arteries to form

nasal and inferior nasal. They pierce the sclera behind

the circulus arteriosus major, near the root of

the equator and drain into superior and inferior

iris. Several branches arise from the circulus

ophthalmic veins which in turn drain into the

arteriosus major and supply the ciliary processes

cavernous sinus.

DISEASES OF THE UVEAL TRACT

137

CONGENITAL COLOBOMA

CONGENITAL ANOMALIES OF

OF THE UVEAL TRACT

UVEAL TRACT

Congenital coloboma (absence of tissue) of iris (Fig.

7.6), ciliary body and choroid (Fig. 7.7) may be seen

HETEROCHROMIA OF IRIS

in association or independently. Coloboma may be

It refers to variations in the iris colour and is a common

typical or atypical.

congenital anomaly. In heterochromia iridium colour

of one iris differs from the other. Sometimes, one sector

of the iris may differ from the remainder of iris; such a

condition is called heterochromia iridis. Congenital

heterochromia must be differentiated from the

acquired heterochromia seen in heterochromic cyclitis,

siderosis and malignant melanoma of iris.

CORECTOPIA

It refers to abnormally eccentric placed pupil.

Normally pupil is placed slightly nasal to the centre.

POLYCORIA

In this condition, there are more than one pupil.

Fig. 7.6. Typical coloboma of the iris.

CONGENITAL ANIRIDIA (IRIDREMIA)

It refers to congenital absence of iris. True aniridia,

i.e., complete absence of the iris is extremely rare.

Usually, a peripheral rim of iris is present and this

condition is called ‘Clinical aniridia'. Zonules of

the lens and ciliary processes are often visible. The

condition is usually familial and may be associated

with glaucoma due to angle anomalies.

PERSISTENT PUPILLARY MEMBRANE

It represents the remnants of the vascular sheath of

the lens. It is characterised by stellate-shaped shreds

of the pigmented tissue coming from anterior surface

of the iris (attached at collarette) (Fig. 7.5). These

float freely in the anterior chamber or may be attached

to the anterior surface of the lens.

Fig. 7.7. Coloboma of the choroid.

Typical coloboma is seen in the inferonasal

quadrant and occurs due to defective closure of

the embryonic fissure.

Atypical coloboma is occasionally found in other

positions.

Complete coloboma extends from pupil to the optic

nerve, with a sector-shaped gap occupying about

one-eighth of the circumference of the retina, choroid,

ciliary body, iris, and causing a corresponding

indentation of the lens where the zonular fibres are

Fig. 7.5. Persistent pupillary membrane.

missing.

138

Comprehensive OPHTHALMOLOGY

IV. ETIOLOGICAL (DUKE ELDER'S)

UVEITIS

CLASSIFICATION

1. Infective uveitis

GENERAL CONSIDERATIONS

2. Allergic uveitis

The term uveitis strictly means inflammation of the

3. Toxic uveitis

uveal tissue only. However, practically there is always

4. Traumatic uveitis

some associated inflammation of the adjacent

5. Uveitis associated with non-infective systemic

structures such as retina, vitreous, sclera and cornea.

diseases

Due to close relationship of the anatomically distinct

6. Idiopathic uveitis

parts of the uveal tract, the inflammatory process

usually tends to involve the uvea as a whole.

ETIOLOGY OF UVEITIS

Despite a great deal of experimental research and

CLASSIFICATION

many sophisticated methods of investigations,

I. ANATOMICAL CLASSIFICATION

etiology and immunology of the uveitis is still largely

not understood. Even today, the cause of many

Anterior uveitis. It is inflammation of the uveal

clinical conditions is disputed (remains presumptive)

tissue from iris up to pars plicata of ciliary body.

and in many others etiology is unknown. The

It may be subdivided into :

etiological concepts of uveitis as proposed by Duke

Iritis, in which inflammation predominantly

Elder, in general, are discussed here.

affects the iris.

Iridocyctitis in which iris and pars plicata part

1. Infective uveitis. In this, inflammation of the uveal

of ciliary body are equally involved, and

tissue is induced by invasion of the organisms. Uveal

Cyclitis, in which pars plicata part of ciliary

infections may be exogenous, secondary or

body is predominantly affected.

endogenous.

Intermediate uveitis. It includes inflammation of

i Exogenous infection wherein the infecting

the pars plana and peripheral part of the retina

organisms directly gain entrance into the eye

and underlying ‘choroid’. It is also called ‘pars

from outside. It can occur following penetrating

planitis'.

injuries, perforation of corneal ulcer and post-

Posterior uveitis. It refers to inflammation of the

operatively (after intraocular operations). Such

choroid (choroiditis). Always there is associated

infections usually result in an acute iridocyclitis

inflammation of retina and hence the term

of suppurative

(purulent) nature, which soon

‘chorioretinitis’ is used.

turns into

endophthalmitis or even

Panuveitis. It is inflammation of the whole uvea.

panophthalmitis.

ii Secondary infection of the uvea occurs by spread

II.

CLINICAL CLASSIFICATION

of infection from neighbouring structures, e.g.,

Acute uveitis. It has got a sudden symptomatic

acute purulent conjunctivitis. (pneumo-coccal and

onset and the disease lasts for about six weeks

gonococcal), keratitis, scleritis, retinitis, orbital

to 3 months.

cellulitis and orbital thrombophlebitis.

Chronic uveitis. It frequently has an insiduous

iii Endogenous infections are caused by the entrance

and asymptomatic onset. It persists longer than

of organisms from some source situated elsewhere

3 months to even years and is usually diagnosed

in the body, by way of the bloodstream.

when it causes defective vision.

Endogenous infections play important role in the

inflammations of uvea.

III. PATHOLOGICAL CLASSIFICATION

Types of infectious uveitis. Depending upon the

1. Suppurative or purulent uveitis.

causative organisms, the infectious uveitis may be

2. Non-suppurative uveitis. It has been further

subdivided in two groups (Wood’s classification).

classified as follows:

(i) Non-granulomatous uveitis, and

i. Bacterial infections. These may be granulo-

(ii) Granulomatous uveitis

matous e.g., tubercular, leprotic, syphilitic,

DISEASES OF THE UVEAL TRACT

139

brucellosis or pyogenic such as streptococci,

In phacoanaphytic endophthalmitis, lens proteins

staphylococci, pneumococci and gonococcus.

play role of autoantigens. Similarly, sympathetic

ii. Viral infections associated with uveitis are herpes

ophthalmitis has been attributed to be an

simplex, herpes zoster and cytomegalo inclusion

autoimmune reaction to uveal pigments, by some

virus (CMV).

workers.

iii. Fungal uveitis is rare and may accompany

v. HLA-associated uveitis: Human leucocytic

systemic aspergillosis, candidiasis and

antigens

(HLA) is the old name for the

blastomycosis. It also includes presumed ocular

histocompatibility antigens. There are about 70 such

histoplasmosis syndrome.

antigens in human beings, on the basis of which an

iv. Parasitic uveitis is known in toxoplasmosis,

individual can be assigned to different HLA

toxocariasis, onchocerciasis and amoebiasis.

phenotypes. Recently, lot of stress is being laid on

v. Rickettsial uveitis may occur in scrub typhus

the role of HLA in uveitis, since a number of

and epidemic typhus.

diseases associated with uveitis occur much more

2. Allergic (hypersensitivity linked) uveitis. Allergic

frequently in persons with certain specific HLA-

uveitis is of the commonest occurrence in clinical

phenotype. A few examples of HLA-associated

practice. The complex subject of hypersensitivity

diseases with uveitis are as follows:

linked inflammation of uveal tissue is still not clearly

HLA-B27. Acute anterior uveitis associated with

understood. It may be caused by the following ways:

ankylosing spondylitis and also in Reiter’s

i. Microbial allergy. In this, primary source of

syndrome.

infection is somewhere else in the body and the

HLA-B5: Uveitis in Behcet’s disease.

escape of the organisms or their products into the

HLA-DR4 and DW15: Vogt Koyanagi Harada’s

bloodstream causes sensitisation of the uveal tissue

disease.

with formation of antibodies. At a later date a

3. Toxic uveitis. Toxins responsible for uveitis

renewal of infection in the original focus may again

can be endotoxins, endocular toxins or exogenous

cause dissemination of the organisms or their

toxins.

products (antigens); which on meeting the sensitised

Endotoxins, produced inside the body play a

uveal tissue excite an allergic inflammatory response.

Primary focus of infection can be a minute

major role. These may be autotoxins or microbial

tubercular lesion in the lymph nodes or lungs. Once

toxins (produced by organisms involving the body

it used to be the most common cause of uveitis

tissues). Toxic uveitis seen in patients with acute

worldwide, but now it is rare. However, in developing

pneumococcal or gonococcal conjunctivitis and in

countries like India tubercular infections still play an

patients with fungal corneal ulcer is thought to be

important role. Other sources of primary focus are

due to microbial toxins.

streptococcal and other infections in the teeth,

ii.

Endocular toxins are produced from the ocular

paranasal sinuses, tonsils, prostate, genitals and

tissues. Uveitis seen in patients with blind eyes,

urinary tract.

long-standing retinal detachment and intraocular

ii.

Anaphylactic uveitis. It is said to accompany

haemorrhages is said to be due to endocular toxins.

the systemic anaphylactic reactions like serum

Other examples are uveitis associated with intraocular

sickness and angioneurotic oedema.

tumours and phacotoxic uveitis.

iii. Atopic uveitis. It occurs due to airborne

iii. Exogenous toxins causing uveitis are irritant

allergens and inhalants, e.g., seasonal iritis due to

chemical substances of inorganic, animal or

pollens. A similar reaction to such materials as

vegetative origin. Certain drugs producing uveitis

danders of cats, chicken feather, house dust, egg

(such as miotics and cytotoxic drugs) are other

albumin and beef proteins has also been noted.

examples of exogenous toxins.

iv. Autoimmune uveitis. It is found in association

4. Traumatic uveitis. It is often seen in accidental or

with autoimmune disorders such as Still’s disease,

operative injuries to the uveal tissue. Different

rheumatoid arthritis, Wegener’s granulomatosis,

mechanisms which may produce uveitis following

systemic lupus erythematosus, Reiter’s disease and

so on.

trauma include:

140

Comprehensive OPHTHALMOLOGY

Direct mechanical effects of trauma.

sympathetic ophthalmia) showing pathological

Irritative effects of blood products after

features of granulomatous uveitis are caused by

intraocular haemorrhage (haemophthalmitis).

hypersensitivity reactions. While uveitis due to

Microbial invasion.

tissue invasion by leptospirae presents the

Chemical effects of retained intraocular foreign

manifestation of non-granulomatous uveitis.

bodies; and

Nonetheless, the classification is often useful in

Sympathetic ophthalmia in the other eye.

getting oriented towards the subject of uveitis, its

workup and therapy. Therefore, it is worthwhile to

5. Uveitis associated with non-infective

describe the pathological features of these

systemic diseases. Certain systemic diseases

overlapping (both clinically and pathologically)

frequently complicated by uveitis include:

conditions as distinct varieties.

sarocoidosis, collagen related diseases (polyarteritis

1. Pathology of suppurative uveitis. Purulent

nodosa (PAN), disseminated lupus erythematosus

inflammation of the uvea is usually a part of

(DLE), rheumatic and rheumatoid arthritis), metabolic

endophthalmitis or panophthalmitis occurring as a

diseases (diabetes mellitus and gout), disease of the

result, of exogenous infection by pyogenic organisms

central nervous system (e.g., disseminated sclerosis)

which include staphylococcus, streptococcus,

and diseases of skin (psoriasis, lichen planus,

psuedomonas, pneumococcus and gonococcus.

erythema nodosum, pemphigus and so on).

The pathological reaction is characterised by an

6. Idiopathic uveitis. It may be specific or non-

outpouring of purulent exudate and infiltration by

specific.

polymorphonuclear cells of uveal tissue, anterior

i. Idiopathic specific uveitis entities include the

chamber, posterior chamber and vitreous cavity. As a

conditions which have certain special characteristics

result, the whole uveal tissue is thickened and

of their own e.g., pars planitis, sympathetic

necrotic and the cavities of eye become filled with

ophthalmitis and Fuchs’ hetero-chromic iridocyclitis.

pus.

ii. Nonspecific idiopathic uveitis entities include

2. Pathology of non-granulomatous uveitis. Non-

the condition which do not belong to any of the

granulomatous uveitis may be an acute or chronic

known etiological groups. About more than

exudative inflammation of uveal tissue (predominantly

percent cases of uveitis fall in this group.

iris and ciliary body), usually occurring due either to

a physical and toxic insult to the tissue, or as a result

PATHOLOGY OF UVEITIS

of different hypersensitivity reactions.

Inflammation of the uvea fundamentally has the same

The pathological alterations of the nongranu-

characteristics as any other tissue of the body, i.e, a

lomatous reaction consists of marked dilatation and

vascular and a cellular response. However, due to

increased permeability of vessels, breakdown of blood

aqueous barrier with an outpouring of fibrinous

extreme vascularity and looseness of the uveal tissue,

exudate and infiltration by lymphocytes, plasma cells

the inflammatory responses are exaggerated and thus

and large macrophages of the uveal tissue, anterior

produce special results.

chamber, posterior chamber and vitreous cavity. The

Pathologically, inflammations of the uveal tract

inflammation is usually diffuse.

may be divided into suppurative (purulent) and non-

As a result of these pathological reactions iris

suppurative (non-purulent) varieties. Wood has

becomes waterlogged, oedematous, muddy with

further classified non-suppurative uveitis into a non-

blurring of crypts and furrows. As a consequence its

granulomatous and granulomatous types. Although

mobility is reduced, pupil becomes small in size due

morphologic description is still of some value, the

to sphincter irritation and engorgement of radial

rigid division of uveitis by Wood into these two

vessels of iris. Exudates and lymphocytes poured into

categories has been questioned on both clinical and

the anterior chamber result in aqueous flare and

pathological grounds. Certain transitional forms of

deposition of fine KPs at the back of cornea. Due to

uveitis have also been recognised. Some of these

exudates in the posterior chamber, the posterior

(e.g., phacoanaphylactic endophthalmitis and

surface of iris adheres to the anterior capsule of lens

DISEASES OF THE UVEAL TRACT

141

leading to posterior synechiae formation. In severe

white with minimal symptoms even in the presence of

inflammation, due to pouring of exudate from ciliary

signs of severe inflammation.

processes, behind the lens, an exudative membrane

Symptoms

called cyclitic membrane may be formed.

After healing, pin-point areas of necrosis or atrophy

1. Pain. It is dominating symptom of acute anterior

are evident. Subsequent attacks lead to structural

uveitis. Patients usually complain of a dull aching

changes like atrophy, gliosis and fibrosis which cause

throbbing sensation which is typically worse at night.

adhesions, scarring and eventually destruction of

The ocular pain is usually referred along the

eye.

distribution of branches of fifth nerve, especially

3. Pathology of granulomatous uveitis. Granulo-

towards forehead and scalp.

matous uveitis is a chronic inflammation of

2. Redness. It is due to circumcorneal congestion,

proliferative nature which typically occurs in

which occurs as a result of active hyperaemia of

response to anything which acts as an irritant foreign

anterior ciliary vessels due to the effect of toxins,

body, whether it be inorganic or organic material

histamine and histamine-like substances and axon

introduced from outside, a haemorrhage or necrotic

reflex.

tissue within the eye, or one of the certain specific

3. Photophobia and blepharospasm observed in

organisms of non-pyogenic and relatively non-

patients with acute anterior uveitis are due to a reflex

virulent character. The common organisms which

between sensory fibres of fifth nerve (which are

excite this type of inflammation are those responsible

irritated) and motor fibres of the seventh nerve,

for tuberculosis, leprosy, syphilis, brucellosis,

supplying the orbicularis oculi muscle.

leptospirosis, as well as most viral, mycotic, protozoal

and helminthic infections. A typical granulomatous

4. Lacrimation occurs as a result of lacrimatory reflex

inflammation is also seen in sarcoidosis, sympathetic

mediated by fifth nerve (afferent) and secretomotor

ophthalmitis and Vogt-Koyanagi-Harada’s disease.

fibres of the seventh nerve (efferent).

The pathological reaction in granulomatous uveitis

5. Defective vision in a patient with iridocyclitis may

is characterised by infiltration with lymphocytes,

vary from a slight blur in early phase to marked

plasma cells, with mobilization and proliferation of

deterioration in late phase. Factors responsible for

large mononuclear cells which eventually become

visual disturbance include induced myopia due to

epithelioid and giant cells and aggregate into nodules.

ciliary spasm, corneal haze (due to oedema and KPs),

Iris nodules are usually formed near pupillary border

aqueous turbidity, pupillary block due to exudates,

(Koeppe’s nodules). Similar nodular collection of the

complicated cataract, vitreous haze, cyclitic

cells is deposited at the back of cornea in the form of

membrane, associated macular oedema, papillitis or

mutton fat keratic precipitates and aqueous flare is

secondary glaucoma. One or more factors may

minimal. Necrosis in the adjacent structures leads to

contribute in different cases depending upon the

a repairative process resulting in fibrosis and gliosis

severity and duration of the disease.

of the involved area.

Signs

ANTERIOR UVEITIS (IRIDOCYCLITIS)

Slit lamp biomicroscopic examination is essential to

CLINICAL FEATURES

elicit most of the signs of uveitis (Fig. 7.8).

I. Lid oedema usually mild, may accompany a severe

Though anterior uveitis, almost always presents as a

attack of acute anterior uveitis.

combined inflammation of iris and ciliary body

II. Circumcorneal congestion is marked in acute

(iridocyclitis), the reaction may be more marked in iris

iridocyclitis and minimal in chronic iridocyclitis. It

(iritis) or ciliary body (cyclitis). Clinically it may

must be differentiated from superficial congestion

present as acute or chronic anterior uveitis. Main

occurring in acute conjunctivitis.

symptoms of acute anterior uveitis are pain,

photophobia, redness, lacrimation and decreased

III. Corneal signs include; corneal oedema, KPs

vision. In chronic uveitis, however the eye may be

and posterior corneal opacities.

142

Comprehensive OPHTHALMOLOGY

1. Corneal oedema is due to toxic endothelitis and

granulomatous iridocyclitis and are composed of

raised intraocular pressure when present.

epithelioid cells and macrophages. They are large,

thick, fluffy, lardaceous KPs, having a greasy or

2. Keratic precipitates (KPs) are proteinaceous-

waxy appearance. Mutton fat KPs are usually a

cellular deposits occurring at the back of cornea.

few (10 to 15) in number (Fig. 7.9B).

Mostly, these are arranged in a triangular fashion

ii. Small and medium KPs (granular KPs). These are

occupying the centre and inferior part of cornea due

pathognomic of non-granulomatous uveitis and

to convection currents in the aqueous humour (Fig.

are composed of lymphocytes. These small,

7.9). The composition and morphology of KPs varies

discrete, dirty white KPs are arranged irregularly

with the severity, duration and type of uveitis.

at the back of cornea. Small KPs may be hundreds

Following types of KPs may be seen:

in number and form the so called endothelial

i. Mutton fat KPs. These typically occur in

dusting.

Fig. 7.8. Signs of anterior uveitis : A, Diagramatic

Fig. 7.9. Keratic precipitates (KPs); A, Diagramatic

depiction; B, clinical photograph of a patient with acute

depiction; B, Clinical photograph of a patient with

anterior uveitis.

granulomatous anterior uveitis showing mutten fat KPs

and broad segmental synechiae.

Newp4\E:\job\Newage\book\Ophthalmology\Section-I\chp-06\chp-06 Disease of the Uveal Tract.pmd

DISEASES OF THE UVEAL TRACT

143

iii. Red KPs. These are formed when in addition to

inflammatory cells, RBCs also take part in

composition. They may be seen in haemorrhagic

uveitis.

iv. Old KPs. These are sign of healed uveitis. Either

of the above described KPs with healing process

shrink, fade, become pigmented and irregular in

shape (crenated margins). Old mutton fat KPs

usually have a ground glass appearance due to

hyalinization.

3. Posterior corneal opacity may be formed in long-

standing cases of iridocyclitis.

IV. Anterior chamber signs

1. Aqueous cells. It is an early feature of iridocyclitis.

The cells should be counted in an oblique slit-lamp

beam, 3-mm long and 1-mm wide, with maximal light

intensity and magnification, and graded as :

- = 0 cells,

± = 1-5 cells,

+1 = 6-10 cells,

+2 = 11-20 cells,

+3 = 21-50 cells, and

+4 = over 50 cells

2. Aqueous flare. It is due to leakage of protein

particles into the aqueous humour from damaged

blood vessels. It is demonstrated on the slit lamp

examination by a point beam of light passed obliquely

to the plane of iris (Fig. 7.10). In the beam of light,

protein particles are seen as suspended and moving

dust particles. This is based on the ‘Brownian

Fig. 7.10. Aqueous flare; A, Diagramatic depiction;

movements’ or ‘Tyndal phenomenon’. Aqueous flare

B, Clinical photograph of the patient.

is usually marked in nongranulomatous and minimal

in granulomatous uveitis. The flare is graded from ‘0’

to +4. Grade :

= no aqueous flare,

= just detectable;

= moderate flare with clear iris details;

= marked flare (iris details not clear);

= intense flare

(fixed coagulated aqueous

with considerable fibrin).

3. Hypopyon. When exudates are heavy and thick,

they settle down in lower part of the anterior chamber

as hypopyon (sterile pus in the anterior chamber)

(Fig. 7.11).

4. Hyphaema (blood in the anterior chamber): It may

be seen in haemorrhagic type of uveitis.

Fig. 7.11. Hypopyon in acute anterior uveitis.

144

Comprehensive OPHTHALMOLOGY

5. Changes in depth and shape of anterior chamber

Koeppe’s nodules are situated at the pupillary

may occur due to synechiae formation.

border and may initiate posterior synechia.

Busacca’s nodules situated near the collarette

6. Changes in the angle of anterior chamber are

are large but less common than the Koeppe’s

observed with gonioscopic examination. In active

nodules.

stage, cellular deposits and in chronic stage peripheral

4. Posterior synechiae. These are adhesions between

anterior synechiae may be seen.

the posterior surface of iris and anterior capsule of

V. Iris signs

crystalline lens (or any other structure which may be

artificial lens, after cataract, posterior capsule (left

1. Loss of normal pattern. It occurs due to oedema

after extracapsular cataract extraction) or anterior

and waterlogging of iris in active phase and due to

hyaloid face. These are formed due to organisation

atrophic changes in chronic phase. Iris atrophy is

of the fibrin-rich exudates. Morphologically, posterior

typically observed in Fuchs’ heterochromic

synechiae may be segmental, annular or total.

iridocyclitis.

i. Segmental posterior synechiae refers to adhesions

2. Changes in iris colour. Iris usually becomes muddy

of iris to the lens at some points (Fig. 7.8).

in colour during active phase and may show

ii. Annular posterior synechiae (ring synechiae are

hyperpigmented and depigmented areas in healed

360^o adhesions of pupillary margin to anterior

stage.

capsule of lens. These prevent the circulation of

3. Iris nodules (Fig. 7.12). These occur typically in

aqueous humour from posterior chamber to

granulomatous uveitis.

anterior chamber (seclusio pupillae). Thus, the

aqueous collects behind the iris and pushes it

anteriorly (leading to ‘iris-bombe’ formation) (Fig.

7.13). This is usually followed by a rise in

intraocular pressure.

iii. Total posterior synechiae due to plastering of

total posterior surface of iris with the anterior

capsule of lens are rarely formed in acute plastic

type of uveitis. These result in deepening of

anterior chamber (Fig. 7.14).

5. Neovascularsation of iris (rubeosis iridis)

develops in some eyes with chronic iridocyclitis.

Fig. 7.12. Iris nodules: A, Diagramatic depiction;

B, Clinical photograph showing Koeppe’s nodules at the

pupillary margins in a patient with sarcoidosis.

Fig. 7.13. Annular posterior synechia.

DISEASES OF THE UVEAL TRACT

145

4. Pupillary reaction becomes sluggish or may even

be absent due to oedema and hyperaemia of iris which

hamper its movements.

5. Occlusio pupillae results when the pupil is

completely occluded due to organisation of the

exudates across the entire pupillary area.

VII. Changes in the lens

1. Pigment dispersal on the anterior capsule of lens

is almost of universal occurrence in a case of anterior

uveitis.

2. Exudates may be deposited on the lens in cases

with acute plastic iridocyclitis.

3. Complicated cataract may develop as a

complication of persistent iridocyclitis. Typical

Fig. 7.14. Total posterior synechia causing deep

anterior chamber

features of a complicated cataract in early stage are

‘polychromatic luster’ and ‘bread-crumb’ appearance

VI. Pupillary signs

of the early posterior subcapsular opacities. In the

1. Narrow pupil. It occurs in acute attack of

presence of posterior synechiae, the complicated

iridocyclitis (Fig. 7.8B) due to irritation of sphincter

cataract progresses rapidly to maturity (Fig. 7.15).

pupillae by toxins. Iris oedema and engorged radial

VIII. Change in the vitreous

vessels of iris also contribute in making the pupil

Anterior vitreous may show exudates and

narrow.

inflammatory cells after an attack of acute iridocyclitis.

2. Irregular pupil shape. It results from segmental

posterior synechiae formation. Dilatation of pupil with

COMPLICATIONS AND SEQUELAE

atropine at this stage results in festooned pupil

1. Complicated cataract. It is a common

(Fig. 7.8A and Fig. 7.15).

complication of iridocyclitis as described above.

3. Ectropion pupillae (evertion of pupillary margin).

2. Secondary glaucoma. It may occur as an early or

It may develop due to contraction of fibrinous exudate

late complication of iridocyclitis.

on the anterior surface of the iris.

i. Early glaucoma. In active phase of the disease,

presence of exudates and inflammatory cells in

the anterior chamber may cause clogging of

trabecular meshwork resulting in the decreased

aqueous drainage and thus a rise in intraocular

pressure (hypertensive uveitis).

ii. Late glaucoma in iridocyclitis

(post-

inflammatory glaucoma) is the result of pupil

block (seclusio pupillae due to ring synechiae

formation, or occlusio pupillae due to organised

exudates) not allowing the aqueous to flow

from posterior to anterior chamber. There may

or may not be associated peripheral anterior

synechiae formation.

3. Cyclitic membrane. It results due to fibrosis of

exudates present behind the lens. It is a late

complication of acute plastic type of iridocyclitis.

Fig. 7.15. Iridocyctitis with posterior synechiae,

4. Choroiditis. It may develop in prolonged cases

festooned pupil and complicated cataract.

of iridocyclitis owing to their continuity.

146

Comprehensive OPHTHALMOLOGY

5. Retinal complications. These include cystoid

Blood sugar levels to rule out diabetes mellitus.

macular oedema, macular degeneration, exudative

Blood uric acid in patients suspected of having

retinal detachment and secondary periphlebitis

gout.

retinae.

Serological tests for syphilis, toxoplasmosis,

6. Papillitis (inflammation of the optic disc). It may

and histoplasmosis.

be associated in severe cases of iridocyclitis.

Tests for antinuclear antibodies, Rh factor,

7. Band-shaped keratopathy. It occurs as a

LE cells, C-reactive proteins and anti-

complication of long-standing chronic uveitis (Fig.

streptolysin-0.

5.17), especially in children having Still’s disease.

2. Urine examination for WBCs, pus cells, RBC

8. Phthisis bulbi. It is the final stage end result of

and culture to rule out urinary tract infections.

any form of chronic uveitis. In this condition,

3. Stool examination for cyst and ova to rule out

ciliary body is disorganised and so aqueous

parasitic infestations.

production is hampered. As a result of it the eye

4. Radiological investigations include X-rays of

becomes soft, shrinks and eventually becomes a

chest, paranasal sinuses, sacroiliac joints and

small atrophic globe (phthisis bulbi).

lumbar spine.

5. Skin tests. These include tuberculin test, Kveim’s

DIFFERENTIAL DIAGNOSIS

test and toxoplasmin test.

1. Acute red eye. Acute iridocyclitis must be

differentiated from other causes of acute red eye,

TREATMENT OF IRIDOCYCLITIS

especially acute congestive glaucoma and acute

I. Non-specific treatment

conjunctivitis. The differentiating features are

summarised in Table 7.1.

(a) Local therapy

2. Granulomatous versus non-granulomatous

1. Mydriatic-cycloplegic drugs. These are very

uveitis. Once diagnosis of iridocyclitis is established,

useful and most effective during acute phase of

an attempt should be made to know whether the

iridocyclitis. Commonly used drug is 1 percent

condition is of granulomatous or non-granulomatous

atropine sulfate eye ointment or drops instilled 2-3

type. The main clinical differences between the two

times a day. In case of atropine allergy, other

are summarised in Table 7.2.

cycloplegics like 2 percent homatropine or 1 percent

3. Etiological differential diagnosis. Efforts should

cyclopentolate eyedrops may be instilled 3-4 times a

also be made to distinguish between the different

day. Alternatively for more powerful cycloplegic effect

etiological varieties of iridocyclitis. This may be

a subconjunctival injection of 0.25 ml mydricain (a

possible in some cases after thorough investigations

mixture of atropine, adrenaline and procaine) should

and with a knowledge of special features of different

be given. The cycloplegics should be continued for

clinical entities, which are described under the subject

at least 2-3 weeks after the eye becomes quiet,

of ‘special types of iridocyclitis’ (see page 154).

otherwise relapse may occur.

INVESTIGATIONS

Mode of action. In iridocyclitis, atropine (i) gives

These include a battery of tests because of its varied

comfort and rest to the eye by relieving spasm of iris

etiology. However, an experienced ophthalmologist

sphincter and ciliary muscle, (ii) prevents the

soon learns to order a few investigations of

formation of synechiae and may break the already

considerable value, which will differ in individual case

formed synechiae, (iii) reduces exudation by

depending upon the information gained from

decreasing hyperaemia and vascular permeability and

thorough clinical work up. A few common

(iv) increases the blood supply to anterior uvea by

investigations required are listed here:

relieving pressure on the anterior ciliary arteries. As

1. Haematological investigations

a result more antibodies reach the target tissues and

TLC and DLC to have a general information

more toxins are absorbed.

about inflammatory response of body.

2. Corticosteroids, administered locally, are very

ESR to ascertain existence of any chronic

effective in cases of iridocyclitis. They reduce

inflammatory condition in the body.

inflammation by their anti-inflammatory effect; being

DISEASES OF THE UVEAL TRACT

147

Table 7.1: Distinguishing features between acute conjunctivitis, acute iridocyclitis and acute congestive glaucoma.

Feature

Acute

Acute congestive

conjunctivitis

iridocyclitis

glaucoma

Onset

Gradual

Usually gradual

Sudden

Pain

Mild discomfort

Moderate in eye

Severe in eye

and along the first

and the entire

division of trigemi-

trigeminal area

nal nerve

Discharge

Mucopurulent

Watery

Coloured halos

May be present

Absent

Present

Vision

Good

Slightly impaired

Markedly impaired

Congestion

Superficial

Deep ciliary

conjunctival

Tenderness

Absent

Marked

Pupil

Normal

Small and irregular

Large and

vertically oval

Media

Clear

Hazy due to KPs,

Hazy due to

aqueous flare and

edematous

pupillary exudates

cornea

10.

Anterior chamber

Normal

May be deep

Very shallow

11.

Iris

Normal

Muddy

Oedematous

12.

Intraocular pressure

Normal

Usually normal

Raised

13.

Constitutional

Absent

Little

Prostration and

symptoms

vomiting

Table 7.2: Differences between granulomatous and non-granulomatous uveitis.

Feature

Granulomatous

Non-granulomatous

Onset

Insidious

Acute

Pain

Minimal

Marked

Photophobia

Slight

Marked

Ciliary congestion

Minimal

Marked

Keratic precipitates (KPs)

Mutton fat

Small

Aqueous flare

Mild

Marked

Iris nodules

Usually present

Absent

Posterior synechiae

Thick and broad based

Thin and tenuous

Fundus

Nodular lesions

Diffuse involvement

anti-allergic, are of special use in allergic type of

(b) Systemic therapy

uveitis; and due to their antifibrotic activity, they

1. Corticosteroids. When administered systemically

reduce fibrosis and thus prevent disorganisation and

they have a definite role in non-granulomatous

destruction of the tissues. Commonly used steroidal

iridocyclitis, where inflammation, most of the times,

preparations contain dexamethasone, betamethasone,

is due to antigen antibody reaction. Even in other

hydrocortisone or prednisolone (see page 428).

types of uveitis, the systemic steroids are helpful due

Route of administration: Locally, steroids are used

to their potent non-specific anti-inflammatory and

as (i) eye drops 4-6 times a day, (ii) eye ointment at

antifibrotic effects. Systemic corticosteroids are

bed time, and (iii) Anterior sub-Tenon injection is

usually indicated in intractable anterior uveitis

given in severe cases.

resistant to topical therapy.

3. Broad spectrum antibiotic drops, though of no use

Dosage schedules. A wide variety of steroids are

in iridocyclitis, are usually prescribed with topical

available.Usually, treatment is started with high doses

steroid preparations to provide an umbrella cover for

them.

of prednisolone (60-100 mg) or equivalent quantities

148

Comprehensive OPHTHALMOLOGY

of other steroids (dexamethasone or betamethasone).

the underlying cause. Unfortunately, in spite of the

Daily therapy regime is preferred for marked

advanced diagnostic tests, still it is not possible to

inflammatory activity for at least 2 weeks. In the

ascertain the cause in a large number of cases.

absence of acute disease, alternate day therapy

So, a full course of antitubercular drugs for

regime should be chosen. The dose of steroids is

underlying Koch’s disease, adequate treatment for

decreased by a week’s interval and tapered completely

syphilis, toxoplasmosis etc., when detected should

in about 6-8 weeks in both the regimes.

be carried out. When no cause is ascertained, a full

course of broad spectrum antibiotics may be helpful

Note: Steroids (both topical and systemic) may cause

by eradicating some masked focus of infection in

many ocular (e.g., steroid-induced glaucoma and

patients with non-granulomatous uveitis.

cataract) and systemic side-effects. Hence, an eagle’s

eye watchfulness is required for it.

III. Treatment of complications

2. Non-steroidal anti-inflammatory drugs (NSAIDS)

1. Inflammatory glaucoma (hypertensive uveitis).

such as aspirin can be used where steroids are

In such cases, drugs to lower intraocular pressure

contraindicated. Phenylbutazone and oxyphenbuta-

such as 0.5 percent timolol maleate eyedrops twice a

zone are potent anti-inflammatory drugs of particular

day and tablet acetazolamide (250 mg thrice a day)

value in uveitis associated with rheumatoid disease.

3. Immunosuppressive drugs. These should be used

should be added, over and above the usual treatment

only in desperate and extremely serious cases of

of iridocyclitis. Pilocarpine and latanoprost eye drops

uveitis, in which vigorous use of steroids have failed

are contraindicated in inflammatory glaucoma.

to resolve the inflammation and there is an imminent

2. Post-inflammatory glaucoma due to ring

danger of blindness. These drugs are dangerous and

synechiae is treated by laser iridotomy. Surgical

should be used with great caution in the supervision

iridectomy may be done when laser is not available.

of a haematologist and an oncologist. These drugs

However, surgery should be performed in a quiet eye

are specially useful in severe cases of Behcet’s

under high doses of corticosteroids.

syndrome, sympathetic ophthalmia, pars planitis and

3. Complicated cataract requires lens extraction with

VKH syndrome. A few available cytotoxic

guarded prognosis in spite of all precautions. The

immunosuppressive drugs include cyclo-

presence of fresh KPs is considered a contraindication

phosphamide, chlorambucil, azathioprine and

for intraocular surgery.

methotrexate. Cyclosporin is a powerful anti-T-cell

immunosuppressive drug which is effective in cases

4. Retinal detachment of exudative type usually

resistant to cytotoxic immunosuppressive agents, but

settles itself if uveitis is treated aggressively. A

it is a highly renal toxic drug.

tractional detachment requires vitrectomy and

management of complicated retinal detachment, with

poor visual prognosis.

1. Hot fomentation. It is very soothing, diminishes

5. Phthisis bulbi especially when painful, requires

pain and increases circulation, and thus reduces the

removal by enucleation operation.

venous stasis. As a result more antibodies are brought

and toxins are drained. Hot fomentation can be done

POSTERIOR UVEITIS

by dry heat or wet heat.

2. Dark goggles. These give a feeling of comfort,

Posterior uveitis refers to inflammation of the choroid

especially when used in sunlight, by reducing

(choroiditis). Since the outer layers of retina are in

photophobia, lacrimation and blepharospasm.

close contact with the choroid and also depend on it

for the nourishment, the choroidal inflammation

II. Specific treatment of the cuase

almost always involves the adjoining retina, and the

The non-specific treatment described above is very

resultant lesion is called chorioretinitis.

effective and usually eats away the uveal

inflammation, in most of the cases, but it does not

Etiology and pathology

cure the disease, resulting in relapses. Therefore, all

These are same as described for uveitis in general

possible efforts should be made to find out and treat

considerations.

DISEASES OF THE UVEAL TRACT

149

Clinical types

i. Central choroiditis. As the name indicates it

involves the macular area and may occur either

I. Suppurative choroiditis (Purulent inflammation of

alone

(Fig.

7.17) or in combination with

the choroid). It usually does not occur alone and

disseminated choroiditis. A typical patch of central

almost always forms part of endophthalmitis

choroiditis may occur in toxoplasmosis,

(see page 150)

histoplasmosis, tuberculosis, syphilis and rarely

II. Non-suppurative choroiditis. It may be non-

due to visceral larva migrans.

granulomatous or granulomatous (more common).

ii. Juxtacaecal or juxtapapillary choroiditis. It is

Non-suppurative choroidal inflammation is

the name given to a patch of choroiditis involving

characterised by exudation and cellular infiltration,

an area adjoining the optic disc. One example is

resulting in a greyish white lesion hiding the normal

Jensen’s choroiditis which typically occurs in

reddish hue of choroidal vessels.

young persons.

Non-suppurative choroiditis is usually bilateral and

iii. Anterior peripheral choroiditis. It implies

morphologically (depending upon the number and

occurrence of multiple small patches of choroiditis

location of lesions) can be classified into diffuse,

(similar to disseminated choroiditis) only in the

disseminated and circumscribed

(localised)

peripheral part of choroid (anterior to equator).

choroiditis.

Such lesions are often syphilitic in origin.

1. Diffuse choroiditis. It refers to large spreading

iv. Equatorial choroiditis. It involves the choroid in

lesions involving most of the choroidal tissue. It is

the equatorial region only.

usually tubercular or syphilitic in origin.

2. Disseminated choroiditis. It is characterised by

Clinical picture

multiple but small areas of inflammation scattered over

Symptoms. Choroiditis is a painless condition,

the greater part of choroid (Fig. 7.16). Such a condition

usually characterised by visual symptoms due to

may be due to syphilis or tuberculosis, but in many

associated vitreous haze and involvement of the

cases the cause is obscure.

retina. Therefore, small patches situated in periphery

3. Circumscribed/localised/focal choroiditis. It is

may be symptomless and are usually discovered as

characterised by a single patch or a few small patches

healed patches on routine fundus examination. On

of inflammation localised in a particular area. Such

the contrary, a central patch produces marked

patches of choroiditis are described by a name

symptoms which draw immediate attention. Various

depending upon the location of the lesion which are

visual symptoms experienced by a patient of

as follows:

choroiditis are summarised below:

Fig. 7.16. Healed lesions of disseminated chorioretinitis.

Fig. 7.17. A healed patch of central chorioretinitis.

150

Comprehensive OPHTHALMOLOGY

1. Defective vision. It is usually mild due to vitreous

differentiated from the degenerative conditions

haze, but may be severe as in central choroiditis.

such as pathological myopia and retinitis

2. Photopsia. It is a subjective sensation of flashes

pigmentosa.

of light resulting due to irritation of rods and

Complications

cones.

These include extension of the inflammation to

3. Black spots floating in front of the eyes. It is a

anterior uvea, complicated cataract, vitreous

very common complaint of such patients. They

degeneration, macular oedema, secondary

occur due to large exudative clumps in the

periphlebitis retinae and retinal detachment.

vitreous.

4. Metamorphopsia. Herein, patients perceive

Treatment

distorted images of the object. This results due

It is broadly on the lines of anterior uveitis.

to alteration in the retinal contour caused by a

1. Non-specific therapy consists of topical and

raised patch of choroiditis.

systemic corticosteroids. Posterior sub-tenon

injections of depot corticosteroids are effective

5. Micropsia which results due to separation of

in checking the acute phase of posterior uveitis.

visual cells is a common complaint. In this the

Rarely, immunosuppresive agents may be required

objects appear smaller than they are.

to check the inflammation.

6. Macropsia, i.e., perception of the objects larger

2. Specific treatment is required for the causative

than they are, may occur due to crowding together

disease such as toxoplasmosis, toxocariasis,

of rods and cones.

tuberculosis, syphilis, etc.

7. Positive scotoma, i.e., perception of a fixed large

spot in the field of vision, corresponding to the

PURULENT UVEITIS

lesion may be noted by many patients.

Purulent uveitis is suppurative inflammation of the

Signs. Usually there are no external signs and the eye

uveal tract occurring as a result of direct invasion by

the pyogenic organisms. It may start as purulent

looks quiet. However, fine KPs may be seen on

anterior uveitis (iridocyclitis) or purulent posterior

biomicroscopy due to associated cyclitis. Fundus

uveitis (choroiditis) which soon progresses to involve

examination may reveal following signs:

the retina and vitreous, resulting in purulent

1. Vitreous opacities due to choroiditis are usually

endophthalmitis.

present in its middle or posterior part. These may

be fine, coarse, stringy or snowball opacities.

ENDOPHTHALMITIS

2. Features of a patch of choroiditis.

Endophthalmitis is defined as an inflammation of the

i. In active stage it looks as a pale-yellow or

inner structures of the eyeball i.e., uveal tissue and

dirty white raised area with ill-defined edges.

retina associated with pouring of exudates in the

This results due to exudation and cellular

vitreous cavity, anterior chamber and posterior

infiltration of the choroid which hide the

chamber.

choroidal vessels. The lesion is typically

Etiology

deeper to the retinal vessels. The overlying

Etiologically endophthalmitis may be infectious or

retina is often cloudy and oedematous.

non-infectious (sterile).

ii. In atrophic stage or healed stage, when active

inflammation subsides, the affected area

A. Infective endophthalmitis

becomes more sharply defined and delineated

Modes of Infection

from the rest of the normal area. The involved

1. Exogenous infections. Purulent inflammations are

area shows white sclera below the atrophic

generally caused by exogenous infections

choroid and black pigmented clumps at the

following perforating injuries, perforation of

periphery of the lesion (Figs. 7.16 and 7.17). A

infected corneal ulcers or as postoperative

healed patch of chorioretinitis must be

infections following intraocular operations.

DISEASES OF THE UVEAL TRACT

151

2. Endogenous or metastatic endophthalmitis. It

periocular bacterial flora of the eyelids, conjunctiva,

may occur rarely through blood stream from some

and lacrimal sac. Other potential sources of infection

infected focus in the body such as caries teeth,

include contaminated solutions and instruments, and

generalised septicaemia and puerperal sepsis.

environmental flora including that of surgeon and

3. Secondary infections from surrounding

operating room personnel.

structures. It is very rare. However, cases of

Symptoms. Acute bacterial endophthalmitis usually

purulent intraocular inflammation have been

occurs within 7 days of operation and is characterized

reported following extension of infection from

by severe ocular pain, redness, lacrimation,

orbital cellulitis, thrombophlebitis and infected

photophobia and marked loss of vision.

corneal ulcers.

Signs are as follows (Fig. 7.18):

Causative organisms

1. Lids become red and swollen.

1. Bacterial endophthalmitis. The most frequent

2. Conjunctiva shows chemosis and marked

pathogens causing acute bacterial endophthal-

circumcorneal congestion.

mitis are gram positive cocci i.e., staphylococcus

Note: Conjunctival congestion, corneal oedema,

epidermidis and staphylococcus aureus. Other

hypopyon and yellowish white exudates in the

causative bacteria include streptococci, pseudo-

vitreous seen in the pupillary area behind the IOL.

monas, pneumococci and corynebacterium.

Cornea is oedematous, cloudy and ring infiltration

Propionio bacterium acnes and actinomyces are

may be formed.

gram-positive organisms capable of producing

Edges of wound become yellow and necrotic and

slow grade endophthalmitis.

wound may gape (Fig. 7.19) in exogenous form.

2. Fungal endophthalmitis is comparatively rare. It

Anterior chamber shows hypopyon; soon it

is caused by aspergillus, fusarium, candida etc.

becomes full of pus.

Iris, when visible, is oedematous and muddy.

B. Non-infective (sterile) endophthalmitis

Pupil shows yellow reflex due to purulent

Sterile endophthalmitis refers to inflammation of inner

exudation in vitreous. When anterior chamber

structures of eyeball caused by certain toxins/toxic

becomes full of pus, iris and pupil details are not

substances. It occurs in following situations.

seen.

1. Postoperative sterile endophthalmitis may occur

Vitreous exudation. In metastatic forms and in

as toxic reaction to:

cases with deep infections, vitreous cavity is

Chemicals adherent to intraocular lens (IOL) or

filled with exudation and pus. Soon a yellowish

Chemicals adherent to instruments.

white mass is seen through fixed dilated pupil.

2. Post-traumatic sterile endophthalmitis may occur

This sign is called amaurotic cat’s-eye reflex.

as toxic reaction to retained intraocular foreign

Intraocular pressure is raised in early stages, but

body, e.g., pure copper.

in severe cases, the ciliary processes are

3. Intraocular tumour necrosis may present as

destroyed, and a fall in intraocular pressure may

sterile endophthalmitis (masquerade syndrome).

ultimately result in shrinkage of the globe.

4. Phacoanaphylactic endophthalmitis may be

induced by lens proteins in patients with

Morgagnian cataract.

Note: Since postoperative acute bacterial

endophthalmitis is most important, so clinical features

and treatment described below pertain to this

condition.

Clinical picture of acute bacterial endophthalmitis

Acute postoperative endophthalmitis is a

catastrophic complication of intraocular surgery with

an incidence of about 0.1%. Source of infection in

most of the cases is thought to be patient’s own

Fig. 7.18. Postoperative acute endophthalmitis.

152

Comprehensive OPHTHALMOLOGY

Gentamycin is 4 times more retinotoxic (causes

macular infarction) than amikacin. Preferably the

aminoglycosides should be avoided.

The aspirated fluid sample should be used for

bacterial culture and smear examination. If vitreous

aspirate is collected in an emergency when

immediate facilities for culture are not available, it

should be stored promptly in refrigerator at 4°C.

If there is no improvement, a repeat intravitreal

injection should be given after 48 hours taking

into consideration the reports of bacteriological

examination.

2. Subconjunctival injections of antibiotics should

Fig. 7.19. Severe postoperative endophthalmitis

be given daily for 5-7 days to maintain therapeutic

with wound gape.

intraocular concentration :

First choice : Vancomycin 25 mg in 0.5 ml plus.

Treatment

Ceftazidime 100 mg in 0.5 ml

An early diagnosis and vigorous therapy is the

Second choice : Vancomycin 25 mg in 0.5 ml plus

hallmark of the treatment of endophthalmitis.

Cefuroxime 125 mg in 0.5 ml

Following therapeutic regime is recommended for

3. Topical concentrated antibiotics should be

suspected bacterial endophthalmitis.

started immediately and used frequently (every 30

A. Antibiotic therapy

minute to 1 hourly). To begin with a combination of

1. Intravitreal antibiotics and diagnostic tap should

two drugs should be preferred, one having a

be made as early as possible. It is performed

predominant effect on the gram-positive organisms

transconjunctivally under topical anaesthesia from

and the other against gram-negative organisms as

the area of pars plana (4-5 mm from the limbus). The

below:

vitreous tap is made using 23-gauge needle followed

Vancomycin (50 mg/ml) or cefazoline (50mg/ml)

by the intravitreal injection using a disposable

plus.

tuberculin syringe and 30-gauge needle.

Amikacin (20 mg/ml) or tobramycin (15 mg%).

The main stay of treatment of acute bacterial

4. Systemic antibiotics have limited role in the

endophthalmitis is intravitreal injection of antibiotics

management of endophthalmitis, but most of the

at the earliest possible. Usually a combination of two

surgeons do use them.

antibiotics - one effective against gram positive

Ciprofloxacin intravenous infusion 200 mg BD

coagulase negative staphylococci and the other

for 3-4 days followed by orally 500 mg BD for

against gram-negative bacilli is used as below :

6-7 days, or

First choice: Vancomycin 1 mg in 0.1 ml plus

Vancomycin 1 gm IV BD and ceftazidime 2 g IV

ceftazidime 2.25 mg in 0.1 ml.

8 hourly, or

Second choice: Vancomycin 1 mg in 0.1 ml plus

Cefazoline 1.5 gm IV 6 hourly and amikacin 1 gm

Amikacin 0.4 mg in 0.1 ml.

IV three times a day.

Third choice: Vancomycin 1 mg in 0.1 ml plus

B. Steroid therapy

gentamycin 0.2 mg in 0.1 ml.

Steroids limit the tissue damage caused by

Note:

inflammatory process. Most surgeons recommend

Some surgeons prefer to add dexamethasone 0.4

their use after 24 to 48 hours of control of infection

mg in 0.1 ml to limit post-inflammatory conse-

by intensive antibiotic therapy. However, some

quences.

surgeons recommend their immediate use

DISEASES OF THE UVEAL TRACT

153

(controversial). Routes of administration and doses

Profuse watering,

are:

Purulent discharge,

Intravitreal injection of dexamethasone 0.4 mg in

Marked redness and swelling of the eyes, and

0.1ml.

Associated constitutional symptoms are malaise

Subconjunctival injection of dexamethasone

and fever.

mg (1ml) OD for 5-7 days.

Signs are as follows (Fig.7.20):

Topical dexamethasone

(0.1%) or predacetate

Lids show a marked oedema and hyperaemia.

(1%) used frequently.

Eyeball is slightly proptosed, ocular movements

Systemic steroids. Oral corticosteroids should

are limited and painful.

preferably be started after 24 hours of intensive

antibiotic therapy. A daily therapy regime with 60

mg prednisolone to be followed by 50, 40, 30, 20

and 10 mg for 2 days each may be adopted.

C. Supportive therapy

1. Cycloplegics. Preferably

1% atropine or

alternatively

2% homatropine eyedrops should

be instilled TDS or QID.

2. Antiglaucoma drugs.In patients with raised

intraocular pressure drugs such a oral

acetazolamide (250 mg TDS) and timolol (0.5%

BD) may be prescribed.

D. Vitrectomy operation should be performed if the

patient does not improve with the above intensive

therapy for 48 to 72 hours or when the patient presents

Fig. 7.20. Panophthalmitis.

with severe infection with visual acuity reduced to

light perception. Vitrectomy helps in removal of

Conjunctiva shows marked chemosis and ciliary

infecting organisms, toxins and enzymes present in

as well as conjunctival congestion.

the infected vitreous mass.

Cornea is cloudy and oedematous.

Anterior chamber is full of pus.

PANOPHTHALMITIS

Vision is completely lost and perception of light

is absent.

It is an intense purulent inflammation of the whole

Intraocular pressure is markedly raised.

eyeball including the Tenon’s capsule. The disease

Globe perforation may occur at limbus, pus comes

usually begins either as purulent anterior or purulent

out and intraocular pressure falls.

posterior uveitis; and soon a full-fledged picture of

Complications include:

panophthalmitis develops, following through a very

Orbital cellulitis

short stage of endophthalmitis.

Cavernous sinus thrombosis

Etiology

Meningitis or encephalitis

Panophthalmitis is an acute bacterial infection.

Treatment

Mode of infection and causative organisms are

There is little hope of saving such an eye and the

same as described for infective bacterial

pain and toxaemia lend an urgency to its removal.

endophthalmitis (page 150, 151).

1. Anti-inflammatory and analgesics should be

Clinical picture

started immediately to relieve pain.

Symptoms. These include:

2. Broad spectrum antibiotics should be

Severe ocular pain and headache,

administered to prevent further spread of infection

Complete loss of vision,

in the surrounding structures.

154

Comprehensive OPHTHALMOLOGY

3. Evisceration operation should be performed to

SPECIFIC CLINICO-ETIOLOGICAL TYPES OF

avoid the risk of intracranial dissemination of

NON-SUPPURATIVE UVEITIS

infection.

The manifold forms of uveitis have been classified

under various headings. Since the classical

EVISCERATION

description of non-suppurative uveitis by Wood

It is the removal of the contents of the eyeball leaving

(1947) into two main groups non-granulomatous and

behind the sclera. Frill evisceration is preferred over

granulomatous, most of the uveitis patients have

simple evisceration. In it, only about 3-mm frill of the

been categorized according to their gross objective

sclera is left around the optic nerve.

similarites. In spite of the many sophisticated methods

Indications. These include: panophthalmitis,

of investigations, even today, the cause in many

expulsive choroidal haemorrhage and bleeding

clinical conditions is disputed and in others it is

anterior staphyloma.

unknown. However, with the background of present

Surgical steps of frill evisceration (Fig. 7.21)

update knowledge, to some extent, it has been

Initial steps upto separation of the conjunctiva

possible to assign a patient with uveitis to a particular

and Tenon’s capsule are similar to enucleation.

group based either on the etiological or typical clinical

presentation of the disease. Detailed description of

Removal of cornea: A cut at the limbus is made

each such clinical entity is beyond the scope of this

with a razor blade fragment or with a No. 11

chapter. However, classification and salient features

scalpel blade and then the cornea is excised with

of the ‘specific clinico-etiological’ types of uveitis

corneoscleral scissors.

are described here:

Removal of intraocular contents: The uveal

tissue is separated from the sclera with the help

Classification

of an evisceration spatula and the contents are

UVEITIS ASSOCIATED WITH CHRONIC

scooped out using the evisceration curette.

SYSTEMIC BACTERIAL INFECTIONS:

Separation of extraocular muscles is done as for

1. Tubercular uveitis

enucleation.

2. Syphilitic uveitis

3. Leprotic uveitis

Removal of sclera: Using curved scissors the

II.

UVEITIS ASSOCIATED WITH NON-

sclera is excised leaving behind only a 3-mm frill

INFECTIOUS SYSTEMIC DISEASES

around the optic nerve.

1. Uveitis in sarcoidosis

Closure of Tenon’s capsule and conjunctiva and

2. Behcet’s disease.

other final steps are similar to enucleation.

III.

UVEITIS ASSOCIATED WITH ARTHRITIS

1. Uveitis with Ankylosing spondylitis

2. Reiter’s syndrome

3. Still’s disease

IV. PARASITIC UVEITIS

1. Toxoplasmosis

2. Toxocariasis

3. Onchocerciasis

4. Amoebiasis

V. FUNGAL UVEITIS

1. Presumed ocular histoplasmosis syndrome

2. Candidiasis

VI. VIRAL UVEITIS

1. Herpes simplex uveitis

2. Herpes zoster uveitis

3. Acquired cytomegalovirus uveitis

Fig. 7.21. Removal of intraocular contents in

4. Uveitis in acquired immune deficiency

evisceration.

syndrome (AIDS)

DISEASES OF THE UVEAL TRACT

155

VII. LENS INDUCED UVEITIS

intractable uveitis unresponsive to steroid therapy, a

1. Phacotoxic uveitis

positive response to isoniazid test (a dramatic

2. Phacoanaphylactic endophthalmitis

response of iritis to isoniazid 300 mg OD for 3 weeks).

VIII. TRAUMATIC UVEITIS

Treatment. In addition to usual treatment of uveitis,

IX. UVEITIS ASSOCIATED WITH MALIGNANT

chemotherapy with rifampicin and isoniazid should

INTRAOCULAR TUMOURS

be given for 12 months. Systemic corticosteroids

X. IDIOPATHIC SPECIFIC UVEITIS

should be deferred.

SYNDROMES

1. Fuchs’ uveitis syndrome

ACQUIRED SYPHILITIC UVEITIS

2. Intermediate uveitis (pars planitis)

Acquired syphilis is a chronic venereal infection

3. Sympathetic ophthalmitis (see page 413-

caused by Treponema pallidum (spirochaete). It

414)

affects both the anterior and posterior uvea.

4. Glaucomatocyclitic crisis.

5. Vogt-Koyanagi-Harada’s syndrome.

1. Syphilitic anterior uveitis. It may occur as acute

6. Bird shot retinochoroidopathy.

plastic iritis or granulomatous iritis. Acute plastic iritis

7. Acute multifocal placoid pigment epithelio-

typically occurs in the secondary stage of syphilis

pathy (AMPPE)

and also as a Herxheimer reaction 24-48 hours after

8. Serpiginous choroidopathy.

therapeutic dose of the penicillin.

Gummatous anterior uveitis occurs late in the

I. UVEITIS IN CHRONIC SYSTEMIC BACTERIAL

secondary or rarely during the tertiary stage of

INFECTIONS

syphilis. It is characterised by formation of yellowish

TUBERCULAR UVEITIS

red highly vascularised multiple nodules arranged

Tuberculosis is a chronic granulomatous infection

near the pupillary border or ciliary border of iris.

caused by bovine or human tubercle bacilli. It may

2. Syphilitic posterior uveitis. It may occur as

cause both anterior and posterior uveitis. At one time

disseminated, peripheral or diffuse choroiditis.

very common, it is now becoming a rare cause. It

Diagnosis. Once suspected clinically, diagnosis is

accounts for 1% of uveitis in developed countries.

However, in developing countries it still continues to

confirmed by FTA-ABS (fluorescent treponemal

be a common cause of uveitis.

antibody absorption) blood test, which is specific

and more sensitive than TPI (treponema pallidum

1. Tubercular anterior uveitis. It may occur as acute

immobilisation) test and VDRL tests.

non-granulomatous iridocyclitis or granulomatous

anterior uveitis which in turn may be in the form of

Treatment. In addition to local therapy of the uveitis,

miliary tubercular iritis or conglomerate granuloma

patient should be treated by systemic penicillin or

(solitary tuberculoma).

other antisyphilitic drugs.

2. Tubercular posterior uveitis. It may occur as:

LEPROTIC UVEITIS

i. Multiple miliary tubercles in the choroid which

appear as round yellow white nodules one-sixth

Leprosy

(Hansen’s disease) is caused by

to two and half disc diameter in size. These are

mycobacterium leprae which is an acid-fast bacillus.

usually associated with tubercular meningitis.

The disease occurs in two principal forms:

ii. Diffuse or disseminated choroiditis in chronic

lepromatous and tuberculoid. Leprosy involves

tuberculosis.

predominantly anterior uvea; more commonly in

iii. Rarely a large solitary choroidal granuloma.

lepromatous than in the tuberculoid form of disease.

3. Vasculitis. (Eales’ disease). see page 254.

Clinical types. Lepromatous uveitis may occur as

Diagnosis. There is no specific clinical finding in

acute iritis (non-granulomatous) or chronic iritis

tubercular uveitis. Diagnosis is made from positive

(granulomatous).

skin test, associated findings of systemic tuberculosis,

1. Acute iritis. It is caused by antigen-antibody

156

Comprehensive OPHTHALMOLOGY

deposition and is characterised by severe

percent cases) and raised levels of serum angiotensin

exudative reaction.

converting enzyme (ACE). Confirmation of the

2. Chronic granulomatous iritis. It occurs due to

disease is made by histological proof from biopsy of

direct organismal invasion and is characterised

the conjunctival nodule, skin lesions or enlarged

by presence of small glistening ‘iris pearls’ near

lymph node.

the pupillary margin in a necklace form; small

Treatment. Topical, periocular and systemic steroids

pearls enlarge and coalesce to form large pearls.

constitute the treatment of sarcoid uveitis, depending

Rarely, a nodular lepromata may be seen.

upon the severity.

Treatment. Besides usual local therapy of iridocyclitis

antileprotic treatment with Dapsone 50-100 mg daily

BEHCET’S DISEASE

or other drugs should also be instituted.

It is an idiopathic multisystem disease characterised

by recurrent, non-granulomatous uveitis, aphthous

II. UVEITIS IN NON-INFECTIOUS SYSTEMIC

ulceration, genital ulcerations and erythema

DISEASES

multiforme.

UVEITIS IN SARCOIDOSIS

Etiology. It is still unknown; the basic lesion is an

Sarcoidosis is a multi-system disease of unknown

obliterative vasculitis probably caused by circulating

etiology, characterised by formation of non-

immune complexes. The disease typically affects the

caseating epithelioid cell granuloma in the affected

young men who are positive for HLA-B51.

tissue. The disease typically affects young adults,

Clinical features. Uveitis seen in Behcet’s disease is

frequently presenting with bilateral hilar lympha-

typically bilateral, acute recurrent iridocyclitis

denopathy, pulmonary infiltration, skin and ocular

associated with hypopyon. It may also be associated

lesions.

with posterior uveitis, vitritis, periphlebitis retinae and

Ocular lesions occur in 20-50 percent patients and

include: uveitis, vitritis with snowball opacities in

retinitis in the form of white necrotic infiltrates.

inferior vitreous, choroidal and retinal granulomas,

Treatment. No satisfactory treatment is available, and

periphlebitis retinae with ‘candle wax droppings',

thus the disease has got comparatively poor visual

conjunctival sarcoid nodule and keratoconjunctivitis

prognosis. Corticosteroids may by helpful initially

sicca.

but ultimate response is poor. In some cases the

Clinical types. Sarcoid uveitis accounts for 2 percent

disease may be controlled by chlorambucil.

cases of uveitis. It may present as one of the following:

VOGT-KOYANAGI-HARADA (VKH) SYNDROME

1. Acute iridocyclitis

(non-granulomatous). It is

It is an idiopathic multisystem disorder which includes

frequently unilateral, associated with acute

cutaneous, neurological and ocular lesions. The

sarcoidosis characterised by hilar lymph-

adenopathy and erythema nodosum.

disease is comparatively more common in Japanese

2. Chronic iridocyclitis. It is more common than

who are usually positive for HLA-DR4 and DW15.

acute and presents with typical features of

Clinical features

bilateral granulomatous iridocyclitis. The disease

1. Cutaneous lesions include: alopecia, poliosis and

is often seen in association with chronic

vitiligo.

sarcoidosis characterised by pulmonary fibrosis.

3. Uveoparotid fever (Heerfordt’s syndrome). It is

2. Neurological lesions are in the form of meningism,

encephalopathy, tinnitus, vertigo and deafness.

characterised by bilateral granulomatous pan-

uveitis, painful enlargement of parotid glands,

3. Ocular features are bilateral chronic granulo-

cranial nerve palsies, skin rashes, fever and

matous anterior uveitis, posterior uveitis and

malaise.

exudative retinal detachment.

Diagnosis. Once suspected clinically, it is supported

Treatment. It comprises steroids administered

by positive Kveim test, abnormal X-ray chest (in 90

topically, periocularly and systemically.

DISEASES OF THE UVEAL TRACT

157

III. UVEITIS IN ARTHRITIS

female children more than the male (4:1). It usually

develops before the age of 6 years. Nearly half of the

UVEITIS WITH ANKYLOSING SPONDYLITIS

patients are positive for HLA-DW5 and 75 percent

Ankylosing spondylitis is an idiopathic chronic

are positive for antinuclear antibodies (ANA). The

inflammatory arthritis, usually involving the sac-

onset of uveitis is asymptomatic and the eye is white

roiliac and posterior inter-vertebral joints. The disease

even in the presence of severe uveitis. Therefore,

affects young males (20-40 years) who are positive

slit-lamp examination is mandatory in children

for HLA-B27. About 30 to 35 percent patients with

suffering from JCA.

ankylosing spondylitis develop uveitis.

Complications like posterior synechiae,

Uveitis associated with ankylosing spondylitis is

complicated cataract and band-shaped keratopathy

characteristically an acute, recurrent, non-

are fairly common.

granulomatous type of iridocyclitis. The disease

Treatment is on the usual lines.

usually affects one eye at a time.

Treatment. It is on the lines of usual treatment of

IV. PARASITIC UVEITIS

anterior uveitis. Long-term aspirin or indomethacin

may decrease the recurrences.

TOXOPLASMOSIS

It is a protozoan infestation caused by Toxoplasma

REITER’S SYNDROME

gondii, derived from cats (definitive host). Humans

It is characterised by a triad of urethritis, arthritis and

and other animals (cattle, sheep and pigs) are

conjunctivitis with or without iridocyclitis.

intermediate hosts. The disease primarily affects

Etiology. It is not known exactly. The syndrome

central nervous system (brain and retina). Systemic

typically involves young males who are positive for

toxoplasmosis occurs in humans in two forms:

HLA-B27. The disease occurs in three forms:

congenital and acquired.

postvenereal due to non-gonococcal arthritis,

1. Congenital toxoplasmosis. It is much more

postdysenteric and articular form.

common than the acquired form, and the infestation

Ocular features. These include:

(i) Acute

is acquired by the foetus through transplacental route

mucopurulent conjunctivitis which may be assoc-

from the mother contracting acute infestation during

iated with superifical punctate keratitis. (ii) Acute non-

pregnancy. When pregnant females catch disease,

granulomatous type of iridocyclitis occurs in 20-30

about 49 percent infants are born with the disease

percent cases of Reiter’s syndrome.

which may be active or inactive at birth.

The characteristic triad of congenital

Treatment. The iridocyclitis responds well to usual

toxoplasmosis includes: convulsions, chorio-retinitis

treatment. A course of systemic tetracycline 250 mg

and intracranial calcification. In active stage the

QID for 10 days may be useful in post-venereal form

typical lesion is necrotic granulomatous

suspected of being caused by Chlamydia infection.

retinochoroiditis involving the macular region. Most

JUVENILE CHRONIC ARTHRITIS

of the infants are born with inactive disease,

characterised by bilateral healed punched out heavily

Juvenile chronic arthritis (JCA) is an idiopathic

pigmented chorioretinal scars in the macular area

chronic inflammatory arthritis involving multiple

(Fig. 7.17), which is usually discovered when the child

joints (knee, elbow, ankle and interphalangeal joints)

is brought for defective vision or squint check up.

in children below the age of 16 years. The disease is

also referred as Juvenile rheumatoid arthritis, though

2. Acquired toxoplasmosis. It is very rare (of doubtful

the patients are sero-negative for rheumatoid factor.

existence). The infestation is acquired by eating the

In 30 percent cases, polyarthritis is associated with

under-cooked meat of intermediate host containing

hepatosplenomegaly and other systemic features, and

cyst form of the parasite. Most of the patients are

the condition is labelled as Still’s disease.

subclinical

(asymptomatic); and the typical

Anterior uveitis associated with JCA is a bilateral

chorioretinal lesion similar to congenital

(70%), chronic non-granulomatous disease, affecting

toxoplasmosis is discovered by chance.

158

Comprehensive OPHTHALMOLOGY

3. Recurrent toxoplasmic retinochoroiditis

is usually seen in children between 5 and 15

Pathogenesis. The parasites reaching the foetus

years of age, presenting with unilateral loss of

through placenta involve its brain and retina, and

vision.

also excite antibodies formation. After healing of the

3. Peripheral granuloma. It is situated anterior to

active retinal lesion (with which the infant is born),

the equator and may be associated with vitreous

the parasites remain encysted there in inactive form.

band formation. It may present from 6 to 40 years

After about 10-40 years (average 25 years), the retinal

of age.

cysts rupture and release hundreds of parasites, which

Diagnosis is made on the basis of clinical picture and

by direct invasion cause a fresh lesion of focal

ELISA blood test.

necrotizing retinochoroidits, adjacent to the edge of

Treatment. It consists of periocular (posterior sub-

the old inactive pigmented scar. In addition to this

Tenon) injection of steroid and systemic steroids. Pars

lesion, an inflammation in the iris, choroid and retinal

plana vitrectomy may be required in unresponsive

vessels is excited due to antigen-antibody reaction.

patients with endophthalmitis and in patients with

Clinical features. Recurrent toxoplasmic retino-

vitreous band formation.

choroiditis is a very common disease. It is

characterised by a whitish-yellow, slightly raised area

V. FUNGAL UVEITIS

of infiltration located near the margin of old punched

out scarred lesion in the macular region associated

PRESUMED OCULAR HISTOPLASMOSIS

SYNDROME (POHS)

with severe vitritis. There may be associated non-

granulomatous type of mild anterior uveitis.

Etiology. It is thought to be caused by the fungus

Histoplasma capsulatum (though the fungus has not

Diagnosis. The clinically suspected lesion is

confirmed by ‘Indirect fluorescein antibody test’,

been isolated from the affected eyes; as the disease

haemagglutination test or ELISA test. The old

is more common in areas where histoplamosis is

methylene blue dye test is obsolete.

endemic (e.g., Mississippi-Ohio-Missouri river valley)

and 90 percent of patients with POHS show positive

Treatment. The active lesion of toxoplasmosis is

histoplasmin skin test. POHS has also been reported

treated by topical and systemic steroids along with a

form United Kingdom, suggesting that perhaps some

course of a antitoxoplasmic drug either spiramycin,

other etiological agents are also capable of producing

clindamycin, sulfadiazine or pyremethamine.

the disease.

TOXOCARIASIS

Clinical features. POHS is characterised by following

It is an infestation caused by an intestinal round worm

features:

of dogs (Toxocara canis) and cats (Toxocara catis).

1. Histospots. These are atrophic spots scattered in

The young children who play with dogs and cats or

the mid-retinal periphery. They are roundish,

eat dirt are infested by ova of these worms. These

yellowish-white lesions measuring 0.2 to 0.7 disc

ova develop into larva in the human gut, and then

diameter in size. These begin to appear in early

produce the condition visceral larva migrans (VLM).

childhood and represent the scars of

Ocular toxocariasis. It is ocular infestation by these

disseminated histoplasma choroiditis.

larva and is almost always unilateral. Clinically it can

2. Macular lesion. It starts as atrophic macular scar

present as follows:

(macular histospot); followed by a hole in the

Bruch’s membrane, which then allows ingrowth

1. Toxocara chronic endophthalmitis. It usually

presents with leucocoria due to marked vitreous

of capillaries leading to sub-retinal choroidal

clouding. The condition is seen in children

neovascularisation. Leakage of fluid from the

between the age of

2-10 years and mimics

neovascular membrane causes serous detachment,

retinoblastoma.

which when complicated by repeated

haemorrhages constitutes haemorrhagic

2. Posterior pole granuloma. It presents as a

detachment. Ultimately, there develops fibrous

yellow-white, round, solitary, raised nodule, about

disciform scar, which is associated with a marked

1-2 disc diameter in size, located either at the

macula or in the centrocaecal area. The condition

permanent visual loss.

DISEASES OF THE UVEAL TRACT

159

Diagnosis. The clinical diagnosis is supported but

Anterior uveitis develops in 40-50 percent cases with

not confirmed by positive histoplasmin test, and

HZO within 2 weeks of onset of the skin rashes. A

complement fixation tests (negative in two thirds

typical HZO keratitis may be associated with mild

cases). Fluorescein angiography helps in early

iritis especially in patients with a vesicular eruption

diagnosis of subretinal neovascular membrane.

on the tip of nose. The iridocyclitis is non-

granulomatous characterised by presence of small

Treatment. Early argon laser photocoagulation of

KPs, mild aqueous flare and occasional haemorrhagic

subretinal neovascular membrane may prevent marked

hypopyon. Complications like iris atrophy and

permanent visual loss which occurs due to fibrous

secondary glaucoma are not uncommon. Complicated

disciform scars.

cataract may also develop in late stages.

CANDIDIASIS

Treatment. Topical steroids and cycloplegics to be

It is an opportunistic infection caused by Candida

continued for several months. Systemic acyclovir

albicans. It occurs in immuno-compromised patients

helps in early control of lesions of HZO.

which include: patients suffering from AIDS,

HERPES SIMPLEX UVEITIS

malignancies, those receiving long-term antibiotics,

steroids or cytotoxic drugs. Patients with long-term

It is associated with keratitis in most of the cases. It

indwelling intravenous catheter used for

may be seen in association with dendritic or

haemodialysis, and drug addicts are also prone to

geographical corneal ulceration or with disciform

such infection.

keratitis. Rarely, anterior uveitis may occur even

without keratitis. It is a mild grade non-granulomatous

Ocular candidiasis. It is not a common condition. It

iridocyclitis excited by hypersensitivity reaction.

may occur as anterior uveitis, multifocal

chorioretinitis, or endophthalmitis.

Treatment. Keratitis is treated with antiviral drugs

1. Anterior uveitis is associated with hypopyon.

and cycloplegics. Steroids for iritis are contraindicated

2. Multifocal chorioretinitis is a more common

in the presence of active viral ulcers. Nonsteroidal

lesion. It is characterised by occurrence of multiple

anti-inflammatory drugs may be added in such cases.

small, round, whitish areas, which may be

CYTOMEGALIC INCLUSION DISEASE

associated with areas of haemorrhages with pale

It is a multisystem disease caused by cytomegalo-

centre (Roth’s spots).

virus (CMV). It occurs in two forms: congenital and

3. Candida endophthalmitis is characterised by

acquired.

areas of severe retinal necrosis associated with

vitreoretinal abscesses. Vitreous exudates present

1. Congenital cytomegalic inclusion disease. It

as ‘puff ball’ or

‘cotton ball’ colonies, which

affects the neonates. The infection is acquired either

when joined by exudative strands form ‘string of

transplacentally in utero or during birth from the

pearls’.

infected cervix of mother. Its common systemic

features are sensory deafness, mental retardation and

Treatment. It consists of :

convulsions.

Topical cycloplegics, and antifungal drugs.

Ocular involvement occurs in the form of peripheral,

Systemic antifungal drugs like ketoconazole,

central or total necrotizing chorioretinitis with

flucytosine or amphotericin-B are also needed.

associated vitreous haze. Posterior pole is involved

Pars plana vitrectomy is required for candida

more commonly and the lesions may be similar to

endophthalmitis.

those found in congenital toxoplasmosis. Secondary

involvement of anterior uvea may occur rarely.

VI. VIRAL UVEITIS

2. Acquired cytomegalic inclusion disease. It occurs

UVEITIS IN HERPES ZOSTER OPHTHALMICUS

only in the immunosuppressed patients (due to any

Herpes zoster ophthalmicus (HZO) is the involvement

cause). The infection may be acquired by droplet

of ophthalmic division of fifth nerve by varicella zoster

infection or by transfusion of fresh blood containing

(described on page 103).

infected white cells.

160

Comprehensive OPHTHALMOLOGY

Ocular involvement is in the form of ‘CMV

The disease is characterised by: (i) heterochromia of

retinitis’ characterised by presence of yellow-white

iris, (ii) diffuse stromal iris atrophy, (iii) fine KPs at

exudates (areas of retinal necrosis) associated with

back of cornea, (iv) faint aqueous flare, (v) absence

areas of vasculitis and retinal haemorrhages. Some

of posterior synechiae, (vi) a fairly common rubeosis

eyes may develop exudative retinal detachment.

iridis, sometimes associated with neovascularisation

Ultimately, there occurs total retinal atrophy.

of the angle of anterior chamber, and

(vii)

comparatively early development of complicated

Treatment. There is no specific treatment of CID.

cataract and secondary glaucoma (usually open angle

Recently treatment with intravenous dihydroxy-

type).

propylmethyl guanine has been shown to cause

regression in some cases.

Treatment. Topical corticosteroids are all that is

required. Cycloplegics are not required as usually

VII. LENS-INDUCED UVEITIS

there are no posterior synechiae.

PHACOANAPHYLACTIC UVEITIS

GLAUCOMATOCYCLITIC CRISIS

It is an immunologic response to lens proteins in the

Posner Schlossman syndrome is characterised by :

sensitized eyes presenting as severe granulomatous

(i) recurrent attacks of acute rise of intraocular

anterior uveitis. The disease may occur following

pressure (40-50 mm of Hg) without shallowing of

extracapsular cataract extraction, trauma to lens or

anterior chamber associated with, (ii) fine KPs at the

leak of proteins in hypermature cataract.

back of cornea, without any posterior synechiae, (iii)

Clinical features. These include severe pain, loss of

epithelial oedema of cornea, (iv) a dilated pupil, and

vision, marked congestion and signs of

(v) a white eye (no congestion).

granulomatous iridocyclitis associated with presence

The disease typically affects young adults, 40

of lens matter in the anterior chamber.

percent of whom are positive for HLA-BW54.

Treatment. It consists of removal of causative lens

Treatment. It includes medical treatment to lower

matter, topical steroids and cycloplegics. Visual

intraocular pressure along with a short course of

prognosis is usually poor.

topical steroids.

PHACOTOXIC UVEITIS

SYMPATHETIC OPHTHALMITIS

It is an ill-understood entity. This term is used to

It is a rare bilateral granulomatous panuveitis which

describe mild iridocyclitis associated with the

is known to occur following penetrating ocular trauma

presence of lens matter in the anterior chamber either

usually associated with incarceration of uveal tissue

following trauma or extracapsular cataract extraction

in the wound. The injured eye is called ‘exciting eye’

or leak from hypermature cataracts. The uveal

and the fellow eye which also develops uveitis is

response due to direct toxic effect of lens matter or a

called ‘sympathising eye’. For details see page 413

mild form of allergic reaction is yet to be ascertained.

ACUTE POSTERIOR MULTIFOCAL PLACOID

Treatment. It consists of removal of lens matter,

PIGMENT EPITHELIOPATHY (APMPPE)

topical steroids and cycloplegics.

It is a rare idiopathic self-limiting disorder

characterised by bilateral, deep, placoid, cream

VIII. TRAUMATIC UVEITIS (See page 405)

coloured or grey white chorioretinal lesions involving

IX. UVEITIS ASSOCIATED WITH INTRAOCULAR

the posterior pole and post-equatorial part of the

TUMOURS (See page 281)

fundus. Visual loss, seen in early stage due to macular

lesions, usually recovers within 2 weeks.

X. IDIOPATHIC SPECIFIC UVEITIS SYNDROMES

Complications though rare include mild anterior

uveitis, vascular sheathing, exudative retinal

FUCHS’ UVEITIS SYNDROME (FUS)

detachment. After healing, multifocal areas of

Fuchs’ heterochromic iridocyclitis is a chronic non-

depigmentation and pigment clumping involving the

granulomatous type of low grade anterior uveitis. It

retinal pigment epithelium are left. No treatment is

typically occurs unilaterally in middle-aged persons.

effective.

DISEASES OF THE UVEAL TRACT

161

SERPIGINOUS GEOGRAPHICAL

Complications of long-standing pars planitis include:

CHOROIDOPATHY

cystoid macular oedema, complicated cataract and

It is a rare, idiopathic, recurrent, bilaterally

tractional retinal detachment.

assymetrical inflammation involving the

Treatment

choriocapillaris and pigment epithelium of the retina.

1. Corticosteroids administered systemically and as

The disease typically affects patients between 40 and

repeated periocular injections may be effective in

60 years of age and is characterised by cream coloured

some cases.

patches with hazy borders present around the optic

disc which spread in a tongue fashion. After few weeks

2. Immunosuppressive drugs may be helpful in

the lesions heal leaving behind punched out areas of

steroid resistant cases.

retinal pigment epithelium and choroidal atrophy. No

3. Peripheral cryotherapy is also reported to be

treatment is effective.

effective.

BIRD-SHOT RETINOCHOROIDOPATHY

DEGENERATIVE CONDITIONS OF

It is a rare, idiopathic, bilaterally symmetrical chronic

multifocal chorioretinitis characterised by numerous

THE UVEAL TRACT

flat creamy-yellow spots due to focal chorioretinal

hypopigmentation, resembling the pattern of ‘bird-

(A) DEGENERATIONS OF THE IRIS

shot scatter from a shotgun’. The disease, more

1. Simple iris atrophy. It is characterised by

common in females than males, typically affects

depigmentation with thinning of iris stroma. Small

middle-aged healthy persons who are positive for

patches of depigmentation are usually seen near the

HLA-A29. It runs a long chronic course of several

pupillary margin. A patch of simple iris atrophy may

years.

be senile, post-inflammatory, glaucomatous or

Treatment with corticosteroids is usually not

neurogenic due to lesions of the ciliary ganglion.

effective.

2. Essential iris atrophy. It is a rare idiopathic

INTERMEDIATE UVEITIS (PARS PLANITIS)

condition characterised by unilateral progressive

atrophy of the iris. The condition typically affects

It denotes inflammation of pars plana part of ciliary

young females 5 times more than the males. Initially

body and most peripheral part of the retina.

there occurs displacement of pupil away from the

Etiology. It is an idiopathic disease usually affecting

atrophic zone. Slowly the iris tissue melts away at

both eyes (80 percent) of children and young adults.

many places resulting in pseudopolycoria. In

Pars planitis is a rather common entity, constituting 8

advanced cases, intractable glaucoma supervenes

percent of uveitis patients.

due to formation of dense anterior peripheral

Clinical features. Symptoms. Most of the patients

synechiae.

present with history of floaters. Some patients may

3. Iridoschisis. It is a rare bilateral atrophy occurring

come with defective vision due to associated cystoid

as a senile degeneration in patients over 65 years of

macular oedema.

age. It may also occur as a later effect of iris trauma. It

Signs. The eye is usually quiet. Slit-lamp examination

is characterised by formation of a cleft between the

may show: mild aqueous flare, and fine KPs at the back

anterior and posterior stroma of the iris. As a

of cornea. Anterior vitreous may show cells. Fundus

consequence the strands of anterior stroma float into

examination with indirect ophthalmoscope reveals the

the anterior chamber.

whitish exudates present near the ora serrata in the

inferior quadrant. These typical exudates are referred

as snow ball opacities. These may coalesce to form a

grey white plaque called snow banking.

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Comprehensive OPHTHALMOLOGY

(B) DEGENERATIONS AND DYSTROPHIES

TUMOURS OF THE UVEAL TRACT

OF THE CHOROID

I. Primary choroidal degenerations

CLASSIFICATION

TUMOURS OF CHOROID

1. Senile central choroidal atrophy. It is

a) Benign

1. Naevus

characterised by formation of multiple drusens

2. Haemangioma

(colloid bodies) which look as yellowish spots. These

3. Melanocytoma

are scattered throughout the fundus, but more marked

4. Choroidal osteoma

in the macular area.

b) Malignant

1. Melanoma

2. Central areolar choroidal atrophy. It comprises

II. TUMOURS OF CILIARY BODY

bilateral punched out, circular atrophic lesion in the

a) Benign

1. Hyperplasia

2. Benign cyst

macular region. The lesion is characterised by white

3. Meduloepithelioma

shining sclera, traversed by large ribbon-shaped

b) Malignant

1. Melanoma

choroidal vessels. Thus, there occurs atrophy of the

III. TUMOURS OF IRIS

choriocapillaris, retinal pigment epithelium and

a) Benign

1. Naevus

photoreceptors.

2. Benign cyst

3. Essential gyrate atrophy. It is an inborn error of

3. Naevoxanthoend-

amino acid (ornithine) metabolism characterised by

othelioma

b) Malignant

1. Melanoma

progressive patches of atrophy of choroid and retinal

pigment epithelium (RPE). The disease begins in first

TUMOURS OF THE CHOROID

decade of life with symptoms of night blindness and

Naevus

progresses slowly to involve the whole fundus by

It is a commonly occurring asymptomatic lesion,

the age of 40-50 years with preservation of only

usually diagnosed on routine fundus examination. It

macula.

typically presents as a flat, dark grey lesion with

feathered margins, usually associated with overlying

4. Choroidremia. It is a hereditary choroidal

colloid bodies.

dystrophy involving the males. The disease begins

Once diagnosed, it should be followed regularly,

in first decade of life with symptoms of night

since it may undergo malignant change which is

blindness and fine whitish patches of choroidal and

evidenced by: (i) Increasing pigmentation or height

RPE atrophy. The lesions progress slowly and by the

of the naevus. (ii) Appearance of orange patches of

age of 40 years almost whole of the choroidal tissue

lipofuscin over the surface and (iii) Appearance of

and RPE disappear rendering the patient blind. At

serous detachment in the area of a naevus.

this age fundus picture is characterised by whitish

Choroidal haemangioma

sclera with overlying almost normal retinal vessels.

It occurs in two forms:

5. Myopic chorioretinal degeneration. (see page 34)

1. Localised choroidal haemangioma. It presents

as a raised, dome-shaped, salmon pink swelling

II. Secondary choroidal degeneration

usually situated at the posterior pole of the eye.

Overlying retina may show serous detachment,

It occurs following inflammatory lesions of the

cystoid degeneration and pigment epithelium

fundus. It is characterised by scattered area of

mottling. Fluorescein angiography is usually

chorioretinal atrophy and pigment clumping.

diagnostic.

Ophthalmoscopic picture resembles retinitis

2. Diffuse choroidal haemangioma. It is seen in

pigmentosa and hence also labelled sometimes as

association with Sturge-Weber syndrome and causes

‘pseudoretinitis pigmentosa’.

diffuse deep red discoloration of the fundus.

DISEASES OF THE UVEAL TRACT

163

Melanocytoma

4. Necrotic melanomas. These make up the remaining

It is a rare tumour which presents as a jet black lesion

5% of the all tumours. In these tumours the

around the optic disc.

predominant cell type is unrecognizable.

Choroidal osteoma

Clinical picture

It is a very rare benign tumour which presents as

For the purpose of discription only the clinical picture

elevated, yellowish-orange lesion in the posterior

can be divided into four stages.

pole. It typically affects the young women.

1. Quiescent stage. During this stage symptoms

depend upon the location and size of tumour. Small

Malignant melanoma of choroid

tumour located in the periphery may not produce any

It is the most common primary intraocular tumour of

symptom, while tumours arising from the posterior

adults, usually seen between 40-70 years of age. It is

pole present with early visual loss. A large tumour

rare in blacks and comparatively more common in

associated with exudative retinal detachment may

whites. It arises from the neural crest derived pigment

produce marked loss of vision.

cells of the uvea as a solitary tumour and is usually

Signs. Fundus examination during this stage may

unilateral.

reveal following signs:

Pathology

i. A small tumour limited to the choroid; appears as

Gross pathology. The tumour may arise from a pre-

an elevated pigmented oval mass (Fig. 7.22).

existing naevus or denovo from the mature

Rarely the tumour may be amelanotic. The earliest

melanocytes present in the stroma. It may occur in

pathognomic sign at this stage is appearance of

two forms:

orange patches in the pigment epithelium due to

1. Circumscribed (pedunculated) tumour. Initially

accumulation of the lipofuscin.

it appears as flat, slate-grey area, which becomes

raised and pigmented with growth and eventually

ruptures through the Bruch’s membrane (Collar-

Stud tumour). Further, growth of the tumour

produces exudative retinal detachment.

2. Diffuse

(flat) malignant melanoma: It spreads

slowly throughout the uvea, without forming a

tumour mass. It accounts for only

5 percent

cases. In it symptoms occur late.

Histopathology. Microscopically uveal melanomas

are following four types (Modified Callender’s classi-

fication):

1. Spindle cell melanomas. These are composed of

spindle-shaped cells and make up 45% of all

tumours. Such tumours have best prognosis (80

percent 10 year survival).

Fig. 7.22. Fundus photograph showing choroidal

2. Epithelioid cell melanomas. These consist of

melanoma as raised pigmented subretinal mass.

large, oval or round, pleomorphic cells with larger

nuclei and abundant acidophilic cytoplasm. This

ii. A large tumour which penetrates through the

type of tumours have the worst prognosis (35

Bruch’s membrane and grows in the subretinal

percent 10 year survival). These make up 5% of

space is characterised by a large exudative retinal

all tumours.

detachment (Fig. 7.23). At the central summit, the

3. Mixed cell melanomas. These are composed of

retina is in contact with the tumour. Ribbon-like

both spindle and epithelioid cells and thus carry

wide vessels are seen coursing over the tumour

an intermediate prognosis (45 percent 10 year

surface in the area. Other associated features

survival). These make up 45% of all tumours.

which can be seen occasionally include subretinal

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Comprehensive OPHTHALMOLOGY

or intraretinal haemorrhage, choroidal folds and

Signs. (i) Conjunctiva is chemosed and congested.

vitreous haemorrhage. As the tumour grows, the

(ii) Cornea may show oedema. (iii) Anterior chamber

exudative retinal detachment deepens and

is usually shallow. (iv) Pupil is fixed and dilated. (v)

gradually the tumour fills the whole eye.

Lens is usually opaque, obstructing the back view.

(vi) Intraocular pressure is raised, usually eye is stony

2. Glaucomatous stage. It develops when tumour is

hard. (vii) Sometimes features of iridocyclitis may be

left untreated during the quiescent stage. Glaucoma

seen due to tumour-induced uveitis.

may develop due to obstruction to the venous outflow

3. Stage of extraocular extension. Due to progressive

by pressure on the vortex veins, blockage of the angle

growth the tumour may burst through sclera, usually

of anterior chamber by forward displacement of the

at the limbus. The extraocular spread may occur even

lens iris diaphragm due to increasing growth of the

early along the perivascular spaces of the vortex veins

tumour.

or ciliary vessels. It is followed by rapid fungation

Symptoms. The patient complains of severe pain,

and involvement of extraocular tissues resulting in

redness and watering in an already blind eye.

marked proptosis (Fig. 7.24).

Fig. 7.24. Extensive malignant melanoma of the

choroid involving orbit.

4. Stage of distant metastasis. Lymphatic spread is

usually not known. Blood-borne metastasis usually

occurs in the liver and is the commonest cause of

death.

Differential diagnosis

1. During quiescent stage differential diagnosis may

be considered as below:

i. A small tumour without an overlying exudative

retinal detachment should be differentiated

from a naevus, melanocytoma and hyperplasia

of the pigment epithelium.

ii. A tumour with overlying exudative retinal

detachment should be differentiated from simple

retinal detachment and other causes of

exudative detachment especially choroidal

haemangioma and secondary deposits.

Fig. 7.23. Malignant melanoma of the choroid causing

exudative retinal detachment : A; Diagramatic depiction in

2. During glaucomatous stage differentiation is to

cut section ; B, Fundus photograph.

be made from other causes of acute glaucoma.

DISEASES OF THE UVEAL TRACT

165

Investigations

stereotactically localized volume of tissue with

1. Indirect ophthalmoscopic examination. It allows

the help of Gamma knife.

three-dimensional stereoscopic view of the lesion.

2. Enucleation. It is indicated for for very larger

It also depicts the presence of shifting fluid

tumours in which conservative methods to salvage

which is pathognomic of exudative retinal

the eyeball are not effective.

detachment.

3. Exenteration or debulking with chemotherapy

2. Transillumination test. It indicates a tumour mass

and radiotherapy is required in the stage of

and thus helps to differentiate from choroidal

extraocular spread.

detachment and simple retinal detachment.

4. Palliative treatment with chemotherapy and

3. Ultrasonography: Both A and B scan help to

immunotherapy may be of some use in prolonging

outline the tumour mass in the presence of hazy

life of the patients with distant metastasis.

media.

4. Fluorescein angiography is of limited diagnostic

TUMOURS OF CILIARY BODY

value because there is no pathognomic pattern.

5. Radioactive tracer: It is based on the fact that

Hyperplasia and benign cyst

the neoplastic tissue has an increased rate of

These are insignificant lesions of the ciliary body.

phosphate (32p) uptake.

Medulloepithelioma (diktyoma)

6. MRI. Choroidal melanomas are hyperintense in

T1-weighted and hypointense in T2-weighted

It is a rare congenital tumour arising from the non-

images.

pigmented epithelium of the ciliary body. It presents

in the first decade of life.

Treatment

1. Conservative treatment to salvage the eyeball

Malignant melanoma

should be tried unless the tumour is very large.

In the ciliary body it is usually diagnosed very late,

Methods used and their indications are:

due to its hidden location. It may extend anteriorly,

i. Brachytherapy is usually the treatment of choice

posteriorly or grow circumferentially.

in tumours less than 10mm in elevation and less

Clinical features

than

20 mm in basal diameter. Supplemental

transpupillary thermotherapy may be required to

1. Earliest features of a localised melonoma include

enhance the results.

slight hypotony, unaccountable defective vision

ii. External beam radiotherapy with protons or

and localised ‘sentinel’ dilated episcleral veins in

helium ions is indicated in tumours unsuiatable

the quadrant containing tumour.

for brachytherapy either because of size or

2. An anterior spreading tumour may present as

posterior location to within 4mm of disc or fovea.

follows:

iii. Transpupillary thermotherapy (TTT) with diode

i. It may cause pressure on the lens resulting in

laser is indicated in selected small tumours,

anterior displacement, subluxation and cataract

particularly if pigmented and located near the

formation.

fovea or optic disc. It can also be supplemented

ii. It may involve iris and is visible immediately.

over brachytherapy to enhence results.

Soon it may involve the angle of anterior

iv. Trans-scleral local resection is indicated in

chamber resulting in secondary glaucoma.

tumours that are too thick for radiotherapy and

iii. It may extend out through sclera along the

usually less than 16mm in diameter. It is a very

vessels, presenting as an epibulbar mass.

difficult procedure which is performed under

3. Posterior spreading tumour may involve choroid

systemic arterial hypotension.

v. Stereostatic radiosurgery is a new method

and present as exudative retinal detachment.

indicated in large tumours. It involves single-

4. The tumour may extend circumferentially

session delivery of ionizing radiation to a

involving whole of the ciliary body.

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Comprehensive OPHTHALMOLOGY

Pathological features

Naevoxanthoendothelioma

It is a rare fleshy vascular lesion seen in babies. It

These are similar to that of choroidal melanoma.

may cause recurrent hyphaema. It is treated with

Treatment

X-rays or steroids.

1. Enucleation. It is required for large ciliary body

Malignant melanoma

tumours extending anteriorly, posteriorly or

It presents as a single or multiple rapidly growing

circumferentially.

vascular nodules. It spreads in the angle producing

2. Local resection. Cyclectomy or irido-cyclectomy

secondary glaucoma. It may penetrate through limbus

may be enough, if fortunately tumour is detected

and present as epibulbar mass. Pathological features

in early stage.

are similar to that of melanoma of the choroid.

TUMOURS OF IRIS

Treatment

1. Wide iridectomy. It is performed for a tumour

Naevus

limited to the iris.

It is the most common lesion of the iris. It presents as

2. Iridocyclectomy. It is required for a tumour

a flat, pigmented, circumscribed lesion of variable size.

involving iris and ciliary body.

Rarely malignant change may occur in it, so it should

3. Enucleation. It should be performed when iris

be observed.

melanoma is associated with secondary glaucoma.

Diseases of

CHAPTER

the Lens

ANATOMY AND PHYSIOLOGY

Manual small incision cataract surgery

Applied anatomy

Phacoemulsification

Applied physiology and biochemistry

Surgical techniques of extracapsular

cataract extraction for childhood cataract

CATARACT

Congenital and developmental cataract

Intraocular lens implantation

Acquired cataract

Complications of cataract surgery and their

Management of cataract

management

SURGICAL TECHNIQUES FOR

DISPLACEMENTS OF THE LENS

CATARACT EXTRACTION

Subluxation

Intracapsular cataract extraction

Dislocation

Conventional extracapsular cataract

extraction

CONGENITAL ANOMALIES OF THE LENS

capsule is thickest at pre-equator regions (14 µ) and

ANATOMY AND PHYSIOLOGY

thinnest at the posterior pole (3 µ).

2. Anterior epithelium. It is a single layer of cuboidal

APPLIED ANATOMY

cells which lies deep to the anterior capsule. In the

The lens is a transparent, biconvex, crystalline

equatorial region these cells become columnar, are

structure placed between iris and the vitreous in

actively dividing and elongating to form new lens

a saucer shaped depression the patellar fossa.

fibres throughout the life. There is no posterior

Its diameter is 9-10 mm and thickness varies with

epithelium, as these cells are used up in filling the

age from 3.5 mm (at birth) to 5 mm (at extreme of

central cavity of lens vesicle during development of

age). Its weight varies from 135 mg (0-9 years) to

the lens.

255 mg (40-80 years of age).

3. Lens fibres. The epithelial cells elongate to form

It has got two surfaces: the anterior surface is

less convex (radius of curvature 10 mm) than the

lens fibres which have a complicated structural form.

posterior (radius of curvature 6 mm). These two

Mature lens fibres are cells which have lost their

surfaces meet at the equator.

nuclei. As the lens fibres are formed throughout the

Its refractive index is

1.39 and total power is

life, these are arranged compactly as nucleus and

15-16 D. The accommodative power of lens varies

cortex of the lens (Fig. 8.2).

with age, being 14-16 D (at birth); 7-8 D (at 25

i. Nucleus. It is the central part containing the

years of age) and 1-2 D (at 50 years of age).

oldest fibres. It consists of different zones, which

are laid down successively as the development

Structure (Fig. 8.1)

proceeds. In the beam of slit-lamp these are seen

1. Lens capsule. It is a thin, transparent, hyaline

as zones of discontinuity. Depending upon the

membrane surrounding the lens which is thicker over

period of development, the different zones of the

the anterior than the posterior surface. The lens

lens nucleus include:

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Comprehensive OPHTHALMOLOGY

Fig. 8.2. Y-shaped sutures of the fetal nuclear fibres.

arranged in three groups:

i. The fibres arising from pars plana and anterior

part of ora serrata pass anteriorly to get inserted

anterior to the equator.

Fig. 8.1. Structure of the crystalline lens.

ii. The fibres originating from comparatively

anteriorly placed ciliary processes pass posteriorly

to be inserted posterior to the equator.

Embryonic nucleus. It is the innermost part of

iii. The third group of fibres passes from the summits

nucleus which corresponds to the lens upto

of the ciliary processes almost directly inward to

the first 3 months of gestation. It consists of

be inserted at the equator.

the primary lens fibres which are formed by

elongation of the cells of posterior wall of lens

APPLIED PHYSIOLOGY AND BIOCHEMISTRY

vesicle.

The crystalline lens is a transparent structure playing

Fetal nucleus. It lies around the embryonic

main role in the focussing mechanism for vision. Its

nucleus and corresponds to the lens from 3

physiological aspects include :

months of gestation till birth. Its fibres meet

Lens transparency,

around sutures which are anteriorly Y-shaped

Metabolic activities of the lens, and

and posteriorly inverted Y-shaped (Fig.8.2).

Accommodation (see page 39)

Infantile nucleus corresponds to the lens from

birth to puberty, and

Lens transparency

Adult nucleus corresponds to the lens fibres

Factors that play significant role in maintaining

formed after puberty to rest of the life.

outstanding clarity and transparency of lens are:

ii. Cortex. It is the peripheral part which comprises

Avascularity,

the youngest lens fibres.

Tightly-packed nature of lens cells,

4. Suspensory ligaments of lens (Zonules of Zinn).

The arrangement of lens proteins,

Also called as ciliary zonules, these consist

Semipermeable character of lens capsule,

essentially of a series of fibres passing from ciliary

Pump mechanism of lens fibre membranes that

body to the lens. These hold the lens in position and

regulate the electrolyte and water balance in the

enable the ciliary muscle to act on it. These fibres are

lens, maintaining relative dehydration and

DISEASES OF THE LENS

169

Auto-oxidation and high concentration of reduced

on chemical exchanges with the aqueous humour. The

glutathione in the lens maintains the lens proteins

chemical composition of the lens vis a vis aqueous

in a reduced state and ensures the integrity of

humour and the chemical exchange between the two

the cell membrane pump.

is depicted in Fig. 8.3.

Pathways of glucose metabolism. Glucose is very

Metabolism

essential for the normal working of the lens. Metabolic

Lens requires a continuous supply of energy (ATP)

activity of the lens is largely limited to epithelium,

for active transport of ions and aminoacids,

and cortex, while the nucleus is relatively inert. In the

maintenance of lens dehydration, and for a

lens, 80% glucose is metabolised anaerobically by

continuous protein and GSH synthesis. Most of the

the glycolytic pathway, 15 percent by pentose hexose

energy produced is utilized in the epithelium which is

the major site of all active transport processes. Only

monophosphate (HMP) shunt and a small proportion

about 10-20% of the ATP generated is used for protein

via oxidative Kreb's citric acid cycle. Sorbitol pathway

synthesis.

is relatively inconsequential in the normal lens;

Source of nutrient supply. The crystalline lens, being

however, it is extremely important in the production

an avascular structure is dependent for its metabolism

of cataract in diabetic and galactosemic patients.

Fig. 8.3. Chemical composition of the lens vis-a-vis aqueous humour and the chemical exchange (pump-leak mechanism)

between them. Values are in m moles/kg of lens water unless otherwise stated.

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Comprehensive OPHTHALMOLOGY

6. Polar cataract. It involves the capsule and

CATARACT

superficial part of the cortex in the polar region

only and may be:

Definition

i. Anterior polar cataract

The crystalline lens is a transparent structure. Its

ii. Posterior polar cataract

transparency may be disturbed due to degenerative

process leading to opacification of lens fibres.

CONGENITAL AND DEVELOPMENTAL

Development of an opacity in the lens is known as

CATARACTS

cataract.

These occur due to some disturbance in the normal

Classification

growth of the lens. When the disturbance occurs

A. Etiological classification

before birth, the child is born with a congenital

cataract. Therefore, in congenital cataract the opacity

I. Congenital and developmental cataract

is limited to either embryonic or foetal nucleus.

II. Acquired cataract

1. Senile cataract

Developmental cataract may occur from infancy to

2. Traumatic cataract (see page 405)

adolescence. Therefore, such opacities may involve

3. Complicated cataract

infantile or adult nucleus, deeper parts of cortex or

4. Metabolic cataract

capsule. Developmental cataract typically affects the

5. Electric cataract

particular zone which is being formed when this

6. Radiational cataract

process is disturbed. The fibres laid down previously

7. Toxic cataract e.g.,

and subsequently are often normally formed and

Corticosteroid-induced cataract

remain clear. Congenital and developmental opacities

ii. Miotics-induced cataract

assume most variegated appearance and minute

iii. Copper (in chalcosis) and iron (in sidero-

opacities (without visual disturbance) are very

sis) induced cataract.

common in normal population. These are detected

8. Cataract associated with skin diseases

with the beam of slit lamp under full mydriasis.

(Dermatogenic cataract).

9. Cataract associated with osseous diseases.

10. Cataract with miscellaneous syndromes e.g.,

i. Dystrophica myotonica

ii. Down's syndrome.

iii. Lowe's syndrome

iv. Treacher - Collin's syndrome

B. Morphological classification (Fig. 8.4)

1. Capsular cataract. It involves the capsule and

may be:

i. Anterior capsular cataract

ii. Posterior capsular cataract

2. Subcapsular cataract. It involves the

superficial part of the cortex

(just below the

capsule) and includes:

i. Anterior subcapsular cataract

ii. Posterior subcapsular cataract

3. Cortical cataract. It involves the major part

of the cortex.

4. Supranuclear cataract. It involves only the

deeper parts of cortex (just outside the nucleus).

5. Nuclear cataract. It involves the nucleus of the

Fig. 8.4. Morphological shapes of cataract.

crystalline lens.

DISEASES OF THE LENS

171

Etiology

II. Polar cataracts

Exact etiology is not known. Some factors which have

1. Anterior polar cataract

been associated with certain types of cataracts are

2. Posterior polar cataract

described below:

III. Nuclear cataract

I. Heredity. Genetically-determined cataract is due to

IV. Lamellar cataract

an anomaly in the chromosomal pattern of the

V. Sutural and axial cataracts

individual. About one-third of all congenital cataracts

1. Floriform cataract

are hereditary. The mode of inheritance is usually

2. Coralliform cataract

dominant. Common familial cataracts include:

3. Spear-shaped cataract

cataracta pulverulenta, zonular cataract (also occurs

4. Anterior axial embryonic cataract

as non-familial), coronary cataract and total soft

VI. Generalized cataracts

cataract (may also occur due to rubella).

1. Coronary cataract

2. Blue dot cataract

II. Maternal factors

1. Malnutrition during pregnancy has been

3. Total congenital cataract

associated with non-familial zonular cataract.

4. Congenital membranous cataract

2. Infections. Maternal infections like rubella are

I. Congenital capsular cataracts

associated with cataract in 50 percent of cases.

1. Anterior capsular cataracts are nonaxial,

Other maternal infections associated with

stationary and visually insignificant.

congenital cataract include toxoplasmosis and

2. Posterior capsular cataracts are rare and can be

cytomegalo-inclusion disease.

3. Drugs ingestion. Congenital cataracts have also

associated with persistent hyaloid artery remnants.

been reported in the children of mothers who

II. Polar cataracts

have taken certain drugs during pregnancy (e.g.,

1. Anterior polar cataract. It involves the central

thalidomide, corticosteroids).

part of the anterior capsule and the adjoining

4. Radiation. Maternal exposure to radiation during

superficial-most cortex. It may arise in the following

pregnancy may cause congenital cataracts.

ways:

III. Foetal or infantile factors

i. Due to delayed development of anterior chamber.

1. Deficient oxygenation (anoxia) owing to placental

In this case the opacity is congenital usually

haemorrhage.

bilateral, stationary and visually insignificant.

2. Metabolic disorders of the foetus or infant

ii. Due to corneal perforation. Such cataracts may

such as galactosemia, galactokinase deficiency

also be acquired in infantile stage and follow

and neonatal hypoglycemia.

contact of the lens capsule with the back of

3. Cataracts associated with other congenital

cornea, usually after perforation due to ophthalmia

anomalies e.g., as seen in Lowe's syndrome,

neonatorum or any other cause.

myotonia dystrophica and congenital icthyosis.

Morphological types: Anterior polar cataracts may

4. Birth trauma.

occur as any of the following morphological patterns:

5. Malnutrition in early infancy may also

i. Thickened white plaque in the centre of capsule.

cause developmental cataract.

ii. Anterior pyramidal cataract. In it the thickened

IV. Idiopathic. About 50 percent cases are sporadic

capsular opacity is cone-shaped with its apex

and of unknown etiology.

towards cornea.

Clinical types

iii. Reduplicated cataract

(double cataract).

Sometimes along with thickening of central point

Congenital and developmental cataracts have been

of anterior capsule, lens fibres lying immediately

variously classified. A simple morphological

classification of congenital and developmental

beneath it also become opaque and are

cataract is as under :

subsequently separated from the capsule by

Congenital capsular cataracts

laying of transparent fibres in between. The

1. Anterior capsular cataract

burried opacity is called ‘imprint’ and the two

2. Posterior capsular cataract

together constitute reduplicated cataract.

172

Comprehensive OPHTHALMOLOGY

2. Posterior polar cataract. It is a very common lens

It is usually bilateral and frequently causes severe

anomaly and consists of a small circular circumscribed

visual defects.

opacity involving the posterior pole.

V. Sutural and axial cataracts

Associations. Posterior polar cataract may be

associated with :

Sutural cataracts are comparatively of common

Persistent hyaloid artery remnants (Mittendorf dot),

occurrence and consist of a series of punctate

Posterior lenticonus, and

opacities scattered around the anterior and posterior

Persistent hyperplastic primary vitreous (PHPV).

Y-sutures. Such cataracts are usually static, bilateral

Types. Posterior polar cataract occurs in two forms:

and do not have much effect on the vision. The

Stationary form and

individual opacities vary in size and shape and have

Progressive form which progresses after birth.

different patterns and thus are named accordingly as

under:

III. Nuclear cataracts

Floriform cataract. Here the opacities

are

i. Cataracta centralis pulverulenta (Embryonic

arranged like the petals of a flower.

nuclear cataract). It has dominant genetic trait and

Coralliform cataract. Here the

opacities

are

occurs due to inhibition of the lens development at a

arranged in the form of a coral.

very early stage and thus, involves the embryonic

nucleus. The condition is bilateral and is characterised

by a small rounded opacity lying exactly in the centre

of the lens. The opacity has a powdery appearance

(pulverulenta) and usually does not affect the vision.

ii. Total nuclear cataract. It usually involves the

embryonic and fetal nucleus and sometimes infantile

nucleus as well. It is characterized by a dense chalky

white central opacity seriously impairing vision. The

opacities are usually bilateral and non progressive.

IV. Lamellar cataract

Lamellar or Zonular cataract refer to the developmental

cataract in which the opacity occupies a discrete zone

in the lens. It is the most common type of congenital

cataract presenting with visual impairment. It

accounts for about 40 percent of the cases.

Etiology. It may be either genetic or environmental

in origin.

Genetic pattern is usually of dominant variety.

Environmental form is associated with deficiency

of vitamin D.

Sometimes maternal rubella infection contracted

between 7th and 8th week of gestation may also

cause lamellar cataract.

Characteristic features. Typically, this cataract occurs

in a zone of foetal nucleus surrounding the embryonic

nucleus (Fig. 8.5).

Occasionally two such rings of opacity are seen.

The main mass of the lens internal and external

Fig. 8.5. Lamellar cataract : A & B, Diagramatic depiction

to the zone of cataract is clear, except for small

as seen by oblique illumination and in optical section

linear opacities like spokes of a wheel (riders)

with the beam of the slit-lamp, respectively;

which may be seen towards the equator.

C, Clinical photograph.

DISEASES OF THE LENS

173

3. Spear-shaped cataract. The lenticular opacities

2. Blue dot cataract. It is also called cataracta-

are in the form of scattered heaps of shining

punctata-caerulea. It usually forms in the first two

crystalline needles.

decades of life. The characteristic punctate opacities

4. Anterior axial embryonic cataract occurs as fine

are in the form of rounded bluish dots situated in the

dots near the anterior Y-suture.

peripheral part of adolescent nucleus and deeper layer

of the cortex. Opacities are usually stationary and do

VI. Generalized cataracts

not affect vision. However, large punctate opacities

1. Coronary cataract (Fig. 8.6). It is an extremely

associated with coronary cataract may marginally

common form of developmental cataract occurring

reduce the vision.

about puberty; thus involving either the adolescent

3. Total congenital cataract. It is a common variety

nucleus or deeper layer of the cortex. The opacities

and may be unilateral or bilateral (Fig. 8.7). In many

are often many hundreds in number and have a regular

cases there may be hereditary character. Its other

radial distribution in the periphery of lens (corona of

important cause is maternal rubella, occurring during

club-shaped opacities) encircling the central axis.

the first trimester of pregnancy. Typically, the child is

Since the opacities are situated peripherally, vision is

born with a dense white nuclear cataract. It is a

usually unaffected. Sometimes the associated large

progressive type of cataract. The lens matter may

punctate opacities may marginally reduce the vision.

remain soft or may even liquefy (congenital

Morgagnian cataract).

Congenital rubella cataract may occur alone or as

part of the classical rubella syndrome which consists

of:

i. Ocular defects

(congenital cataract, salt and

pepper retinopathy and microphthalmos).

ii. Ear defects (deafness due to destruction of organ

of Corti).

iii. Heart defects (patent ductus arteriosus, pulmonary

stenosis and ventricular septal defects).

4. Congenital membranous cataract. Sometimes

there may occur total or partial absorption of

congenital cataract, leaving behind thin membranous

cataract. Rarely there is complete disappearance of

all the lens fibres and only a fine transparent lens

capsule remains behind. Such a patient may be

Fig. 8.6. Coronary cataract : A & B as seen by oblique

illumination and in optical section with the beam of the

slit-lamp, respectively, C, Clinical photograph.

Fig. 8.7. Total congenital cataract.

174

Comprehensive OPHTHALMOLOGY

misdiagnosed as having congenital aphakia. This is

B. Prognostic factors which need to be noted are:

associated with Hallermann-Streiff-Francois

Density of cataract,

Synodrome.

Unilateral or bilateral cataract,

Time of presentation,

Differential diagnosis

Associated ocular defects, and

Congenital cataracts presenting with leukocoria

Associated systemic defects

need to be differentiated from various other conditions

C. Indications and timing of paediatric cataract

presenting with leukocoria such as retinoblastoma,

surgery,

retinopathy of prematurity, persistent hyperplastic

1. Partial cataracts and small central cataracts

primary vitreous (PHPV), etc., (also see page 282)

which are visually insignificant can safely be

ignored and observed or may need non-surgical

Management of congenital and developmental

cataract

treatment with pupillary dilatation.

2. Bilateral dense cataracts should be removed

A. Clinico-investigative work up. A detailed clinico-

early (within 6 weeks of birth) to prevent stimulus

investigative work up is most essential in the

deprivation amblyopia.

management of paediatric cataract. It should aim at

3. Unilateral dense cataract should preferably be

knowing the prognostic factors and indications and

removed as early as possible (within days) after

timing of surgery.

birth. However, it must be born in mind that

1. Ocular examination should be carried out with

visual prognosis in most of the unilateral cases

special reference to:

is very poor even after timely operation because

Density and morphology of cataract

correction of aphakia and prevention of amblyopia

Assessment of visual function is difficult in infants

in infants is an uphill task.

and small children. An idea may be made from the

D. Surgical procedures. Childhood cataracts,

density and morphology of the cataract by

(congenital, developmental as well as acquired) can

oblique illumination examination and fundus

be dealt with anterior capsulotomy and irrigation

examination. Special tests like fixation reflex, forced

aspiration of the lens matter or lensectomy. Surgical

choice preferential looking test, visually evoked

technique of these procedures is described on page

potential (VEP), optic-kinetic nystagmus (OKN)

193.

etc. also provide useful information.

Note. The needling operation (which was performed

Associated ocular defects should be noted (which

in the past) is now obsolete.

include microphthalmos, glaucoma, PHPV, foveal

hypoplasia, optic nerve hypoplasia, and rubella

E. Correction of paediatric aphakia. It is still an

retinopathy etc.

unsolved query. Presently common views are as

2. Laboratory investigations should be carried out

follows:

to detect following systemic associations in non-

Children above the age of

2 years can be

hereditary cataracts:

corrected by implantation of posterior chamber

Intrauterine infections viz. toxoplasmosis, rubella,

intraocular lens during surgery.

cytomegalo virus and herpes virus by TORCH

Children below the age of

2 years should

test.

preferably be treated by extended wear contact

Galactosemia by urine test, for reducing

lens. Spectacles can be prescribed in bilateral

substances, red blood cell transferase and

cases. Later on secondary IOL implantation may

glactokinase levels.

be considered. Present trend is to do primary

Lowe's syndrome by urine chromatography for

implantation at the earliest possible (2-3 months)

amino acids.

specially in unilateral cataract.

Hyperglycemia by blood sugar.

Paediatric IOL: size, design and power. The main

Hypocalcemia by serum calcium and phosphate

concerns regarding the use of IOL in children are the

levels and X-ray skull.

growth of the eye, IOL power considerations,

DISEASES OF THE LENS

175

increased uveal reaction and long-term safety. Present

forms, the cortical (soft cataract) and the nuclear (hard

recommendation are :

cataract). The cortical senile cataract may start as

Size of IOL above the age of 2 years may be

cuneiform (more commonly) or cupuliform cataract.

standard 12 to 12.75-mm diameter for in the bag

It is very common to find nuclear and cortical senile

implantation.

cataracts co-existing in the same eye; and for this

Design of IOL recommended is one-piece PMMA

reason it is difficult to give an accurate assessment

with modified C-shaped haptics (preferably heparin

of their relative frequency. In general, the predominant

coated).

form can be given as cuneiform 70 percent, nuclear 25

Power of IOL. In children between 2-8 years of

percent and cupuliform 5 percent.

age

10% undercorrection from the calculated

Etiology

biometric power is recommended to counter the

Senile cataract is essentially an ageing process.

myopic shift. Below 2 years on undercorrection

Though its precise etiopathogenesis is not clear, the

by 20% is recomended.

various factors implicated are as follows:

F. Correction of amblyopia. It is the central theme

A. Factors affecting age of onset, type and

around which management of childhood cataract and

maturation of senile cataract.

aphakia revolves. In spite of best efforts, it continues

1. Heredity. It plays a considerable role in the

to be the main cause of ultimate low vision in these

incidence, age of onset and maturation of senile

children. For management see page 319.

cataract in different families.

2. Ultraviolet irradiations. More exposure to UV

ACQUIRED CATARACT

irradiation from sunlight have been implicated for

We have studied that congenital and developmental

early onset and maturation of senile cataract in

cataracts occur due to disturbance in the formation

many epidemiological studies.

of the lens fibres, i.e., instead of clear, opaque lens

3. Dietary factors. Diet deficient in certain proteins,

fibres are produced. While, in acquired cataract,

amino acids, vitamins

(riboflavin, vitamin E,

opacification occurs due to degeneration of the

vitamin C), and essential elements have also been

already formed normal fibres. The exact mechanism

blamed for early onset and maturation of senile

and reasons for the degeneration of lens fibres are

cataract.

yet not clear. However, in general any factor, physical,

4. Dehydrational crisis. An association with prior

chemical or biological, which disturbs the critical intra

episode of severe dehydrational crisis

(due to

and extracellular equilibrium of water and electrolytes

diarrhoea, cholera etc.) and age of onset and

or deranges the colloid system within the lens fibres,

maturation of cataract is also suggested.

tends to bring about opacification. The factors

5. Smoking has also been reported to have some

responsible for disturbing such an equilibrium of the

effect on the age of onset of senile cataract.

lens fibres vary in different types of acquired cataracts

Smoking causes accumulation of pigmented

and shall be discussed with the individual type. A

molecules—3 hydroxykynurinine and chrom-

few common varieties of acquired cataract are

ophores, which lead to yellowing. Cyanates in

described here.

smoke causes carbamylation and protein

SENILE CATARACT

denaturation.

Also called as ‘age-related cataract’, this is the

B. Causes of presenile cataract. The term presenile

commonest type of acquired cataract affecting equally

cataract is used when the cataractous changes similar

persons of either sex usually above the age of 50

to senile cataract occur before 50 years of age. Its

years. By the age of 70 years, over 90% of the

common causes are:

individuals develop senile cataract. The condition is

1. Heredity. As mentioned above because of

usually bilateral, but almost always one eye is affected

influence of heredity, the cataractous changes

earlier than the other.

may occur at an earlier age in successive

Morphologically, the senile cataract occurs in two

generations.

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Comprehensive OPHTHALMOLOGY

2. Diabetes mellitus. Age-related cataract occurs

Stages of maturation

earlier in diabetics. Nuclear cataract is more

[A] Maturation of the cortical type of senile

common and tends to progress rapidly.

cataract

3. Myotonic dystrophy is associated with posterior

1. Stage of lamellar separation. The earliest senile

subcapsular type of presenile cataract.

change is demarcation of cortical fibres owing to their

4. Atopic dermatitis may be associated with pre-

separation by fluid. This phenomenon of lamellar

senile cataract (atopic cataract) in 10% of the

separation can be demonstrated by slit-lamp

cases.

examination only. These changes are reversible.

C. Mechanism of loss of transparency. It is

2. Stage of incipient cataract. In this stage early

basically different in nuclear and cortical senile

detectable opacities with clear areas between them

cataracts.

are seen. Two distinct types of senile cortical

1. Cortical senile cataract. Its main biochemical

cataracts can be recognised at this stage:

features are decreased levels of total proteins, amino

(a) Cuneiform senile cortical cataract. It is

acids and potassium associated with increased

characterised by wedge-shaped opacities with clear

concentration of sodium and marked hydration of the

areas in between. These extend from equator towards

lens, followed by coagulation of proteins. The

centre and in early stages can only be demonstrated

probable course of events leading to senile

after dilatation of the pupil. They are first seen in the

opacification of cortex is as shown in the Figure 8.8.

lower nasal quadrant. These opacities are present

2. Nuclear senile cataract. In it the usual

both in anterior and posterior cortex and their apices

degenerative changes are intensification of the age-

slowly progress towards the pupil. On oblique

related nuclear sclerosis associated with dehydration

illumination these present a typical radial spoke-like

and compaction of the nucleus resulting in a hard

pattern of greyish white opacities (Fig. 8.9). On distant

cataract. It is accompanied by a significant increase

direct ophthalmoscopy, these opacities appear as dark

in water insoluble proteins. However, the total protein

lines against the red fundal glow.

content and distribution of cations remain normal.

There may or may not be associated deposition of

Since the cuneiform cataract starts at periphery

pigment urochrome and/or melanin derived from the

and extends centrally, the visual disturbances are

amino acids in the lens.

noted at a comparatively late stage.

(b) Cupuliform senile cortical cataract. Here a saucer-

shaped opacity develops just below the capsule

Fig. 8.9. Diagrammatic depiction of Immature senile cata-

Fig. 8.8. Flow chart depicting probable course of events

ract (cuneiform type): A, as seen by oblique illumination;

involved in occurence of cortical senile cataract.

B, in optical section with the beam of the slit-lamp.

DISEASES OF THE LENS

177

usually in the central part of posterior cortex (posterior

subcapsular cataract), which gradually extends

outwards. There is usually a definite demarcation

between the cataract and the surrounding clear cortex.

Cupuliform cataract lies right in the pathway of the

axial rays and thus causes an early loss of visual

acuity.

3. Immature senile cataract (ISC). In this stage,

opacification progresses further. The cuneiform (Fig.

8.9) or cupuliform patterns can be recognised till the

advanced stage of ISC when opacification becomes

more diffuse and irregular. The lens appears greyish

white (Fig. 8.10) but clear cortex is still present and so

iris shadow is visible.

In some patients, at this stage, lens may become

Fig. 8.11. Mature senile cortical cataract.

swollen due to continued hydration. This condition

is called ‘intumescent cataract'. Intumescence may

bottom, altering its position with change in the

persist even in the next stage of maturation. Due to

position of the head. Such a cataract is called

swollen lens anterior chamber becomes shallow.

Morgagnian cataract (Fig. 8.12). Sometimes in

this stage, calcium deposits may also be seen

4. Mature senile cataract (MSC). In this stage,

on the lens capsule.

opacification becomes complete, i.e., whole of the

cortex is involved. Lens becomes pearly white in

colour. Such a cataract is also labelled as ‘ripe

cataract’ (Fig. 8.11).

5. Hypermature senile cataract (HMSC). When the

mature cataract is left in situ, the stage of

hypermaturity sets in. The hypermature cataract may

occur in any of the two forms:

(a) Morgagnian hypermature cataract: In some

patients, after maturity the whole cortex liquefies

and the lens is converted into a bag of milky

fluid. The small brownish nucleus settles at the

Fig. 8.12. Morgagnian hypermature senile cataract :

Fig. 8.10. Immature senile cortical cataract.

A, diagrammatic depiction; B, Clinical photograph.

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Comprehensive OPHTHALMOLOGY

(b) Sclerotic type hypermature cataract:

Sometimes after the stage of maturity, the cortex

becomes disintegrated and the lens becomes

shrunken due to leakage of water. The anterior

capsule is wrinkled and thickened due to

proliferation of anterior cells and a dense white

capsular cataract may be formed in the pupillary

area. Due to shrinkage of lens, anterior chamber

becomes deep and iris becomes tremulous

(iridodonesis).

[B] Maturation of nuclear senile cataract

In it, the sclerotic process renders the lens inelastic

and hard, decreases its ability to accommodate and

obstructs the light rays. These changes begin

Fig.

8.13. Early nuclear senile cataract.

centrally (Fig. 8.13) and slowly spread peripherally

an oncoming motor vehicle. The amount of glare

almost up to the capsule when it becomes mature;

or dazzle will vary with the location and size of

however, a very thin layer of clear cortex may remain

the opacity.

unaffected.

Uniocular polyopia (i.e., doubling or trebling of

The nucleus may become diffusely cloudy

objects): It is also one of the early symptoms. It

(greyish) or tinted (yellow to black) due to deposition

occurs due to irregular refraction by the lens

of pigments. In practice, the commonly observed

owing to variable refractive index as a result of

pigmented nuclear cataracts are either amber, brown

cataractous process.

(cataracta brunescens) or black (cataracta nigra)

Coloured halos. These may be perceived by

and rarely reddish (cataracta rubra) in colour

some patients owing to breaking of white light

(Fig. 8.14).

into coloured spectrum due to presence of water

Clinical features

droplets in the lens.

Symptoms. An opacity of the lens may be present

Black spots in front of eyes. Stationary black

without causing any symptoms; and may be

spots may be perceived by some patients.

discovered on routine ocular examination. Common

Image blur, distortion of images and misty vision

symptoms of cataract are as follows:

may occur in early stages of cataract.

1. Glare. One of the earliest visual disturbances

Loss of vision. Visual deterioration due to senile

with the cataract is glare or intolerance of bright

cataract has some typical features. It is painless

light; such as direct sunlight or the headlights of

and gradually progressive in nature. Paitents with

Fig. 8.14. Nuclear cataract: A, cataracta brunescens; B, cataracta nigra; and C, Cataracta rubra.

DISEASES OF THE LENS

179

central opacities (e.g., cupuliform cataract) have

early loss of vision. These patients see better

when pupil is dilated due to dim light in the

evening

(day blindness). In patients with

peripheral opacities (e.g. cuneiform cataract) visual

loss is delayed and the vision is improved in

bright light when pupil is contracted. In patients

with nuclear sclerosis, distant vision deteriorates

due to progressive index myopia. Such patients

may be able to read without presbyopic glasses.

This improvement in near vision is referred to as

‘second sight'. As opacification progresses,

vision steadily diminishes, until only perception

of light and accurate projection of rays remains

Fig. 8.15. Diagrammatic depiction of iris

in stage of mature cataract.

shadow in : immature cataract (A) and no iris

shadow in mature cataract (B).

Signs. Following examination should be carried out

to look for different signs of cataract:

1. Visual acuity testing. Depending upon the

pupillary margin

(Fig.

8.15). When lens is

location and maturation of cataract, the visual

completely transparent or completely opaque, no

acuity may range from 6/9 to just PL + (Table 8.1).

iris shadow is formed. Hence, presence of iris

2. Oblique illumination examination. It reveals

shadow is a sign of immature cataract.

colour of the lens in pupillary area which varies

Distant direct ophthalmoscopic examination (for

in different types of cataracts (Table 8.1).

procedure see page 564). A reddish yellow fundal

3. Test for iris shadow. When an oblique beam of

glow is observed in the absence of any opacity

light is thrown on the pupil, a crescentric shadow

in the media. Partial cataractous lens shows black

of pupillary margin of the iris will be formed on

shadow against the red glow in the area of

the greyish opacity of the lens, as long as clear

cataract. Complete cataractous lens does not even

cortex is present between the opacity and the

reveal red glow (Table 8.1).

Table 8.1: Signs of senile cataract

Examination

Nuclear cataract

ISC

MSC

HMSC(M)

HMSC(S)

1. Visual acuity

6/9 to PL+

6/9 to FC+

HM+ to PL+

PL+

2. Colour of lens

Grey, amber,

Greyish white

Pearly white

Milky white

Dirty white with

brown, black

with sinking

hyper-white

or red

brownish

spots

nucleus

3. Iris shadow

Seen

Not seen

4. Distant direct

Central dark

Multiple dark

No red glow

ophthalmoscopy area against red

areas against

but white pupil

milky white

with dilated

fundal glow

red fundal glow

due to complete

pupil

cataract

5. Slit-lamp

Nuclear opacity

Areas of normal Complete cortex Milky white

Shrunken

examination

clear cortex

with cataractous is cataractous

sunken brown- cataractous lens

cortex

ish nucleus

with thickened

anterior capsule

ISC: Immature senile cataract, MSC: Mature senile cataract, HMSC (M) Hypermature senile cataract (Morgagnian),

HMSC (S): Hypermature senile cataract (Sclerotic), PL: Perception of light, HM: Hand movements, FC: Finger

counting.

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Comprehensive OPHTHALMOLOGY

5. Slit-lamp examination should be performed with

The signs observed on above examinations in

a fully-dilated pupil. The examination reveals

different stages of senile cataract are shown in

complete morphology of opacity (site, size, shape,

Table 8.1.

colour pattern and hardness of the nucleus).

Grading of nucleus hardness in a cataractous lens is

Differential diagnosis

important for setting the parameters of machine in

1. Immature senile cataract

(ISC) can be

phacoemulsification technique of cataract extraction.

differentiated from nuclear sclerosis without any

The hardness of the nucleus, depending upon its

cataract as shown in Table 8.3.

colour on slit-lamp examination, can be graded as

shown in Table 8.2 and (Fig. 8.16) :

Table 8.3 : Immature senile cataract versus

nuclear sclerosis

Table 8.2. Grading of nucleus hardness on

ISC

Nuclear sclerosis

slit-lamp biomicroscopy.

1. Painless progressive

Grade of

Description of

Colour of

loss of vision

hardness

nucleus

2. Greyish colour of lens

Grade I

Soft

White or

greenish yellow

3. Iris shadow is present

3. Iris shadow is absent

Grade II

Soft-medium

Yellowish

4. Black spots against red

4. No black spots are

Grade III

Medium-hard

Amber

glow are observed on

seen against red glow

Grade IV

Hard

Brownish

distant direct ophthal-

Grade V

Ultrahard

Blackish

moscopy

(rock-hard)

5. Slit-lamp examination

reveals area of

reveals clear lens

cataractous cortex

6. Visual acuity does not

6. Visual acuity usually

improve on pin-hole

improves on pin-hole

testing

II. Mature senile cataract can be differentiated from

other causes of white pupillary reflex (leukocoria) as

shown in Table 8.4.

Table 8.4 : Differences between mature senile

cataract and leukocoria

MSC

Leukocoria

1. White reflex in pupillary

White reflex in pupillary

area

2. Size of pupil usually

Pupil usually semidila-

normal

ted

3. Fourth Purkinje image is Fourth Purkinje image

absent

is present

4. Slit-lamp examination

Slit-lamp examination

shows cataractous

shows transparent

lens

lens with white reflex

behind the lens

5. Ultrasonography normal Ultrasonography

reveals opacity in the

Fig. 8.16. Slit-lamp biomicroscopic grading of nucleus

vitreous cavity

hardness in cataractous lens.

DISEASES OF THE LENS

181

Complications

Hypocalcaemic cataract

Cataractous changes may be associated with

1. Phacoanaphylactic uveitis. A hypermature cataract

parathyroid tetany, which may occur due to atrophy

may leak lens proteins into anterior chamber. These

or inadvertent removal (during thyroidectomy) of

proteins may act as antigens and induce antigen-

parathyroid glands. Multicoloured crystals or small

antibody reaction leading to uveitis.

discrete white flecks of opacities are formed in the

cortex which seldom mature.

2. Lens-induced glaucoma. It may occur by different

mechanisms e.g., due to intumescent lens

Cataract due to error of copper metabolism

(phacomorphic glaucoma) and leakage of proteins

Inborn error of copper metabolism results in Wilson’s

into the anterior chamber from a hypermature cataract

disease (hepatolenticular degeneration). The green

(phacolytic glaucoma).

‘sunflower cataract’ may be observed rarely in such

patients. The more commonly observed ocular feature

3. Subluxation or dislocation of lens. It may occur

of Wilson’s disease is ‘Kayser-Fleischer ring’ (KF

due to degeneration of zonules in hypermature

ring) in the cornea.

stage.

Cataract in Lowe's syndrome

METABOLIC CATARACTS

Lowe’s (Oculo-cerebral-renal) syndrome is a rare

These cataracts occur due to endocrine disorders and

inborn error of amino acid metabolism.

biochemical abnormalities. A few common varieties

Ocular features include congenital cataract and

of metabolic cataracts are described here.

glaucoma.

Systemic features of this syndrome are mental

Diabetic cataract

retardation, dwarfism, osteomalacia, muscular

Diabetes is associated with two types of cataracts:

hypotonia and frontal prominence.

1. Senile cataract in diabetics appears at an early

age and progresses rapidly.

COMPLICATED CATARACT

2. True diabetic cataract. It is also called ‘snow flake

It refers to opacification of the lens secondary to

cataract’ or ‘snow-storm cataract’. It is a rare

some other intraocular disease. Some authors use the

condition, usually occurring in young adults due to

term secondary cataract for the complicated cataract.

osmotic over-hydration of the lens. Initially a large

Many authors use the term secondary cataract to

number of fluid vacuoles appear underneath the

denote after cataract. Therefore, to avoid confusion

anterior and posterior capsules, which is soon

and controversy, preferably, the term secondary

followed by appearance of bilateral snowflake-like

cataract should be discarded.

white opacities in the cortex.

Etiology

Galactosaemic cataract

The lens depends for its nutrition on intraocular

fluids. Therefore, any condition in which the ocular

It is associated with inborn error of galactose

circulation is disturbed or in which inflammatory

metabolism. Galactosaemia occurs in two forms:

toxins are formed, will disturb nutrition of the

1. Classical galactosaemia occurs due to deficiency

crystalline lens, resulting in development of

of galactose-1 phosphate uridyl-transferase

complicated cataract. Some important ocular

(GPUT); and

conditions giving rise to complicated cataract are listed

2. A related disorder occurs due to deficiency of

here.

galactokinase

(GK).

1. Inflammatory conditions. These include uveal

Characterstic features. Galactosaemia is frequently

inflammations

(like iridocyclitis, parsplanitis,

associated with the development of bilateral cataract

choroiditis), hypopyon corneal ulcer and

(oil droplet central lens opacities). The lens changes

endophthalmitis.

may be reversible and occurrence of cataract may be

2. Degenerative conditions such as retinitis

prevented, if milk and milk products are eliminated

pigmentosa and other pigmentary retinal dystro-

from the diet when diagnosed at an early stage.

phies and myopic chorioretinal degeneration.

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Comprehensive OPHTHALMOLOGY

3. Retinal detachment. Complicated cataract may

fluorophosphate (DFP). Removal of the drug may stop

occur in long-standing cases.

progression and occasionally may cause reversal of

4. Glaucoma (primary or secondary) may sometimes

cataract.

result in complicated cataract. The underlying

Other toxic cataracts

cause here is probably the embarrassment to the

intraocular circulation, consequent to the raised

Other drugs associated with fine toxic cataracts are

pressure.

amiodarone, chlorpromazine, busulphan, gold and

5. Intraocular tumours such as retinoblastoma or

allopurinol.

melanoma may give rise to complicated cataract

RADIATIONAL CATARACT

in late stages.

Exposure to almost all types of radiant energy is

Clinical features

known to produce cataract by causing damage to the

Typically the complicated cataract starts as posterior

lens epithelium. Following types are known:

cortical cataract. Lens changes appear typically in

front of the posterior capsule. The opacity is irregular

1. Infrared (heat) cataract

in outline and variable in density. In the beam of slit-

Prolonged exposure (over several years) to infra-red

lamp the opacities have an appearance like ‘bread-

rays may cause discoid posterior subcapsular

crumb’. A very characteristic sign is the appearance

opacities and true exfoliation of the anterior capsule.

of iridescent coloured particles the so-called

It is typically seen in persons working in glass

‘polychromatic lustre’ of reds, greens and blues. A

industries, so also called as ‘glass-blower’s or glass-

diffuse yellow-haze is seen in the adjoining cortex.

worker’s cataract’.

Slowly the opacity spreads in the rest of the cortex,

2. Irradiation cataract

and finally the entire lens becomes opaque, giving

Exposure to X-rays, γ-rays or neutrons may be

chalky white appearance. Deposition of calcium is

associated with irradiation cataract. There is usually

common in the later stages.

a latent period ranging from 6 months to a few years

TOXIC CATARACTS

between exposure and development of the cataract.

People prone to get such cataracts are inadequately

Corticosteroid-induced cataract

protected technicians, patients treated for malignant

Posterior subcapsular opacities are associated with

tumours and workers of atomic energy plants.

the use of topical as well as systemic steroids. The

exact relationship between dose and duration of

3. Ultraviolet radiation cataract

corticosteroid therapy with the development of

Ultraviolet radiation has been linked with senile

cataract is still unclear. However, in general, prolonged

cataract in many studies.

use of steroids in high doses may result in cataract

formation. Children are more susceptible than adults.

ELECTRIC CATARACT

Therefore, it is recommended that all patients with

It is known to occur after passage of powerful electric

diseases requiring prolonged corticosteroids therapy

current through the body. The cataract usually starts

should be regularly examined on slit-lamp by an

as punctate subcapsular opacities which mature

ophthalmologist. Further, intermittent regimes should

rapidly. The source of current can be a live electricity

be preferred over regular therapy and whenever

wire or a flash of lightning.

possible steroids should be substituted by non-

steroidal anti-inflammatory drugs (NSAIDs).

SYNDERMATOTIC CATARACT

Lens opacities associated with cutaneous disease are

Miotics-induced cataract

termed syndermatotic cataracts. Such cataracts are

Anterior subcapsular granular type of cataract may

bilateral and occur at a young age. Atopic dermatitis is

be associated with long-term use of miotics,

the most common cutaneous disease associated with

particularly long acting cholinesterase inhibitors such

cataract (Atopic cataract). Other skin disorders

as echothiophate, demecarium bromide, disopropyl

associated with cataract include poikiloderma,

DISEASES OF THE LENS

183

vasculare atrophicus, scleroderma and keratotis

Use of dark goggles in patients with central

follicularis.

opacities is of great value and comfort when

worn outdoors.

MANAGEMENT OF CATARACT IN ADULTS

Mydriatics. The patients with a small axial cataract,

Treatment of cataract essentially consists of its

frequently may benefit from pupillary dilatation.

surgical removal. However, certain non-surgical

This allows the clear paraxial lens to participate

measures may be of help, in peculiar circumstances,

in light transmission, image formation and

till surgery is taken up.

focussing. Mydriatics such as

5 percent

phenylephrine or 1 percent tropicamide; 1 drop

A. Non-surgical measures

b.i.d. in the affected eye may clarify vision.

1. Treatment of cause of cataract. In acquired

B. Surgical management

cataracts, thorough search should be made to find

out the cause of cataract. Treatment of the causative

Indications

disease, many a time, may stop progression and

1. Visual improvement. This is by far the most

sometimes in early stages may cause even regression

common indication. When surgery should be advised

of cataractous changes and thus defer the surgical

for visual improvement varies from person to person

treatment. Some common examples include:

depending upon the individual visual needs. So, an

Adequate control of diabetes mellitus, when

individual should be operated for cataract, when the

discovered.

visual handicap becomes a significant deterrent to

Removal of cataractogenic drugs such as

the maintenance of his or her usual life-style.

corticosteroids, phenothiazenes and strong

2. Medical indications. Sometimes patients may be

miotics, may delay or prevent cataractogenesis.

comfortable from the visual point (due to useful vision

from the other eye or otherwise) but may be advised

Removal of irradiation (infrared or X-rays) may

cataract surgery due to medical grounds such as

also delay or prevent cataract formation.

Lens induced glaucoma,

Early and adequate treatment of ocular diseases

Phacoanaphylactic endophthalmitis and

like uveitis may prevent occurrence of complicated

Retinal diseases like diabetic retinopathy or retinal

cataract.

detachment, treatment of which is being hampered

2. Measures to delay progression. Many commercially

by the presence of lens opacities.

available preparations containing iodide salts of

3. Cosmetic indication. Sometimes patient with

calcium and potassium are being prescribed in

mature cataract may insist for cataract extraction (even

abundance in early stages of cataract (especially in

with no hope of getting useful vision), in order to

senile cataract) in a bid to delay its progression.

obtain a black pupil.

However, till date no conclusive results about their

Preoperative evaluation

role are available. Role of vitamin E and aspirin in

Once it has been decided to operate for cataract, a

delaying the process of cataractogenesis is also

thorough preoperative evaluation should be carried

mentioned.

out before contemplating surgery. This should

3. Measures to improve vision in the presence of

include:

incipient and immature cataract may be of great

I. General medical examination of the patient to

solace to the patient. These include:

exclude the presence of serious systemic diseases

Refraction, which often changes with considerable

especially: diabetes mellitus; hypertension and

rapidity, should be corrected at frequent intervals.

cardiac problems; obstructive lung disorders and any

Arrangement of illumination. Patients with

potential source of infection in the body such as

peripheral opacities (pupillary area still free), may

septic gums, urinary tract infection etc.

be instructed to use brilliant illumination.

II. Ocular examination. A thorough examination of

Conversely, in the presence of central opacities,

eyes including slit-lamp biomicroscopy is desirable

a dull light placed beside and slightly behind the

in all cases. The following useful information is

patient’s head will give the best result.

essential before the patient is considered for surgery:

184

Comprehensive OPHTHALMOLOGY

A. Retinal function tests. The retinal function must

9. Objective tests for evaluating retina are required

be explored since, if it is defective, operation will be

if some retinal pathology is suspected. These

valueless, and patient must be warned of the

tests includes ultrasonic evaluation of posterior

prognosis, to avoid unnecessary disappointment and

segment of the eye; electrophysiological studies

medicolegal problems. A few important retinal function

such as ERG

(electroretinogram), EOG

tests are considered here.

(electrooculogram) and VER

(visually-evoked

Light perception (PL). Many sophisticated retinal

response); and indirect ophthalmoscopy if

function tests have been developed, but light

possible.

perception must be present, if there is to be any

B. Search for local source of infection should be

potential for useful vision.

made by ruling out conjunctival infections,

A test for Marcus-Gunn pupillary response

meibomitis, blepharitis and lacrimal sac infection.

(indicative of afferent pathway defect) should be

Lacrimal sac should receive special attention. Lacrimal

made routinely. If present, it is a poor prognostic

syringing should be carried out in each patient with

sign.

history of watering from the eyes. In cases where

Projection of rays (PR). It is a crude but an

chronic dacryocystitis is discovered, either DCR

important and easy test for function of the

peripheral retina. It is tested in a semi-dark room

(dacryocystorhinostomy) or DCT (dacryocystec-

with the opposite eye covered. A thin beam of

tomy) operation should be performed, before the

light is thrown in the patient's eye from four

cataract surgery.

directions (up, down, medial and lateral) and the

C. Anterior segment evaluation by slit-lamp

patient is asked to look straight ahead and point

examination. It is of utmost importance. Presence of

out the direction from which the light seems to

keratic precipitates at the back of cornea, in a case of

come.

complicated cataract, suggests management for subtle

Two-light discrimination test. It gives information

uveitis before the cataract surgery. Similarly,

about macular function. The patient is asked to

information about corneal endothelial condition is also

look through an opaque disc perforated with two

very important, especially if intraocular lens

pin-holes behind which a light is held. The holes

implantation is planned.

are 2 inches apart and kept about 2 feet away

from the eye. If the patient can perceive two

D. Intraocular pressure (IOP) measurement.

lights, it indicates normal macular function.

Preoperative evaluation is incomplete without the

Maddox rod test. The patient is asked to look at

measurement of IOP. The presence of raised IOP

a distant bright light through a Maddox rod. An

needs a priority management.

accurate perception of red line indicates normal

function.

Preoperative medications and preparations

Colour perception. It indicates that some macular

1. Topical antibiotics such as tobramycin or

function is present and optic nerve is relatively

gentamicin or ciprofloxacin QID for 3 days just

normal.

before surgery is advisable as prophylaxis against

Entoptic visualisation. It is evaluated by rubbing

endophthalmitis.

a point source of light (such as bare lighted bulb

2. Preparation of the eye to be operated. Eyelashes

of torch) against the closed eyelids. If the patient

of upper lid should be trimmed at night and the

perceives the retinal vascular pattern in black

eye to be operated should be marked.

outline, it is favourable indication of retinal

3. An informed and detailed consent should be

function. Being subjective in nature, the

obtained.

importance of negative test can be considered if

4. Scrub bath and care of hair. Each patient should

the patient can perceive the pattern with the

be instructed to have a scrub bath including face

opposite eye.

and hair wash with soap and water. Male patients

Laser interferometry. It is a very good test for

measuring the macular potential for visual acuity

must get their beard cleaned and hair trimmed.

in the presence of opaque media.

Female patients should comb their hair properly.

DISEASES OF THE LENS

185

5. To lower IOP, acetazolamide 500 mg stat 2 hours

Contraindications. The only absolute contrain-

before surgery and glycerol 60 ml mixed with

dication for ECCE is markedly subluxated or

equal amount of water or lemon juice, 1 hour

dislocated lens.

before surgery, or intravenous mannitol 1 gm/kg

Advantages of ECCE over ICCE

body weight half an hour before surgery may be

1. ECCE is a universal operation and can be

used.

performed at all ages, except when zonules are

6. To sustain dilated pupil

(especially in

not intact; whereas ICCE cannot be performed

extracapsular cataract extraction) the

below 40 years of age.

antiprostaglandin eyedrops such as indomethacin

2. Posterior chamber IOL can be implanted after

or flurbiprofen should be instilled three times one

ECCE, while it cannot be implanted after ICCE.

day before surgery and half hourly for two hours

3. Postoperative vitreous related problems (such as

immediately before surgery. Adequate dilation of

herniation in anterior chamber, pupillary block

pupil can be achieved by instillation of 1 percent

and vitreous touch syndrome) associated with

tropicamide and

5 percent or

10 percent

ICCE are not seen after ECCE.

phenylephrine eyedrops every ten minutes, one

hour before surgery.

4. Incidence of postoperative complications such

as endophthalmitis, cystoid macular oedema and

Anaesthesia

retinal detachment are much less after ECCE as

Cataract extraction can be performed under general

compared to that after ICCE.

or local anaesthesia. Local anaesthesia is preferred

5. Postoperative astigmatism is less, as the incision

whenever possible (see page 571-573).

is smaller.

Types and choice of surgical techniques

Advantages of ICCE over ECCE

I. Intracapsular cataract extraction (ICCE) . In this

1. The technique of ICCE, as compared to ECCE, is

technique, the entire cataractous lens along with the

simple, cheap, easy and does not need

intact capsule is removed. Therefore, weak and

sophisticated microinstruments.

degenerated zonules are a pre-requisite for this

2. Postoperative opacification of posterior capsule

method. Because of this reason, this technique

is seen in a significant number of cases after

cannot be employed in younger patients where

ECCE. No such problem is known with ICCE.

zonules are strong. ICCE can be performed between

3. ICCE is less time consuming and hence more

40-50 years of age by use of the enzyme alpha-

useful than ECCE for mass scale operations in

chymotrypsin (which will dissolve the zonules).

eye camps.

Beyond 50 years of age usually there is no need of

Types of extracapsular cataract extraction

this enzyme.

The surgical techniques of ECCE presently in vogue

Indications. ICCE has stood the test of time and has

are:

been widely employed for about 50 years over the

Conventional extracapsular cataract extraction

world. Now (for the last 25 years) it has been almost

entirely replaced by planned extracapsular technique.

(ECCE),

At present the only indications of ICCE is markedly

Manual small incision cataract surgery (SICS),

subluxated and dislocated lens.

Phacoemulsification

II. Extracapsular cataract extraction (ECCE). In

Conventional ECCE versus SICS

this technique, major portion of anterior capsule with

Conventional large incision ECCE, though still being

epithelium, nucleus and cortex are removed; leaving

performed by many surgeons, is being largely replaced

behind intact posterior capsule.

by small incision cataract surgery (SICS) techniques.

Indications. Presently, extracapsular cataract

Merits of conventional ECCE over SICS. The only

extraction technique is the surgery of choice for

merit of conventional ECCE over SICS is that it is a

almost all types of adulthood as well as childhood

simple technique to master with short learning curve.

cataracts unless contraindicated.

186

Comprehensive OPHTHALMOLOGY

Dermerits of conventional ECCE over SICS include:

Merits of phacoemulsification over manual SICS

Long incision (10 to 12 mm).

1. Topical anaesthesia may be sufficient for

Multiple sutures are required.

phacoemulsification in expert hands.

Open chamber surgery with high risk of vitreous

2. Postoperative congestion is minimal after

prolapse, operative hard eye and expulsive

phacoemulsification, as phaco is usually

choroidal haemorrhage.

performed through a clear corneal incision.

3. Small incision. The chief advantage of

High incidence of post-operative astigmatism.

phacoemulsification over manual SICS is that it

Postoperative suture-related problems like irritation

can be performed through a smaller (3.2 mm)

and suture abscess etc.

incision.

Postoperative wound-related problems such as

4. Less corneal complications. Phacoemulsification

wound leak, shallowing of anterior chamber and

can be performed in the posterior chamber

iris prolapse.

without prolapsing the nucleus into the anterior

Needs suture removal, during which infection

chamber, thereby minimising the risk of corneal

may occur.

complications.

Merits of manual SICS over phacoemulsification

5. Visual rehablitation is comparetively quicker in

1. Universal applicability i.e., all types of cataracts

phacoemulsification as compared to manual SICS.

including hard cataracts (grade IV and V) can be

6. Postoperative astigmatism is comparatively less

operated by this technique.

when foldable IOLs are implanted through a

2. Learning curve. This procedure is much easier to

smaller incision (3.2 mm).

learn as compared to phacoemulsification.

Demerits of phacoemulsification vis-a-vis manual

3. Not machine dependent. The biggest advantage

SICS

of manual SICS is that it is not machine dependent

1. Learning curve for phacoemulsification is more

and thus can be practised anywhere.

painful both for the surgeons and patients.

4. Less surgical complications. Disastrous

2. Complications encountered during phacoe-

complication like nuclear drop into vitreous cavity

mulsification like nuclear drop are unforgiving.

is much less than phacoemulsification technique.

3. Machine dependent. This procedure is solely

5. Operating time in manual SICS is less than that

machine dependent and in the event of an

of phocoemulsification, especially in hard cataract.

unfortunate machine failure in the middle of

Therefore, it is ideal for mass surgery.

surgery one has to shift to conventional ECCE.

6. Cost effective. With manual SICS, the expenses

4. High cost. Cost of this technique is very high

because of expensive machine, accessories and

are vastly reduced as compared to considerable

maintenance.

expenses in acquiring and maintaining phaco

5. Limitations. It is very difficult to deal with hard

machine. There is no need to spend on

cataracts (grade IV and V) with this technique,

consumable items like the phacotip, sleeves,

and also there is high risk of serious corneal

tubing and probe. Further, in SICS always PMMA

complications due to more use of phaco energy

IOLs are used which are much cheeper than

in such cases.

foldable IOLs.

Conclusion. Inspite of the demerits listed above

Demerits of manual SICS over phacoemulsification

the phacoemulsification has become the preferred

method of cataract extraction world wide because

1. Conjunctival congestion persists for 5-7 days at

the complication rate in the expert hands is minimal

the site of conjunctival flap.

and the technique provides an almost quiet eye

2. Mild tenderness sometime may be present owing

early postoperatively and an early visual

to scleral incision.

rehabilitation. However, for the masses, especially

3. Postoperative hyphaema may be noted

in developing countries, the manual SICS offers the

sometimes.

advantages of sutureless cataract surgery as a low

4. Surgical induced astigmatism is more as the

cost alternative to phacoemulsification with the

incision in SICS is large (about 6 mm) as compared

added advantages of having wider applicability and

to phacoemulsification (about 3.2 mm).

an easier learning curve.

DISEASES OF THE LENS

187

movements and the lens is then extracted out by

SURGICAL TECHNIQUES FOR

sliding movements. In this technique, upper pole

CATARACT EXTRACTION

of the lens is delivered first (Fig. 8.17F).

iii. Capsule forceps method. The Arruga's capsule

INTRACAPSULAR CATARACT EXTRACTION

holding forceps is introduced close into the

Presently, the technique of intracapsular cataract

anterior chamber and the anterior capsule of the

extraction (ICCE) is obsolete and sparingly performed

lens is caught at 6 O'clock position. The lens is

world wide. However, the surgical steps are described

lifted slightly and its zonules are ruptured by

in detail as a mark of respect to the technique which

gentle sideways movements. Then the lens is

has been widely employed for about 50 years over

extracted with gentle sliding movements by the

the world and also to care for the emotions of few

forceps assisted by a pressure at

6 O'clock

elderly surgeons who are still performing this

position on the limbus by the lens expressor.

operation (though unethical) at some places in

iv. Irisophake method. This technique is obsolete

developing countries.

and thus not in much use.

Surgical steps of the ICCE technique are as follows:

v. Wire vectis method. It is employed in cases with

1. Superior rectus (bridle) suture is passed to fix the

subluxated or dislocated lens only. In this method

eye in downward gaze (Fig. 8.17A).

the loop of the wire vectis is slide gently below

2. Conjunctival flap (fornix based) is prepared to

the subluxated lens, which is then lifted out of

expose the limbus (Fig. 8.17B) and haemostasis is

the eye.

achieved by wet field or heat cautery. All surgeons

7. Formation of anterior chamber. After the delivery

do not make conjunctival flap.

of lens, iris is reposited into the anterior chamber with

3. Partial thickness groove or gutter is made through

the help of iris repositor and chamber is formed by

about two-thirds depth of anterior limbal area from

injecting sterile air or balanced salt solution.

9.30 to 2.30 O'clock (150^o) with the help of a razor

8. Implantation of anterior chamber (ACIOL) (Figs.

blade knife (Fig. 8.17C).

8.17 G & H). For details see page 197.

4. Corneoscleral section. The anterior chamber is

9. Closure of incision is done with 5 to 7 interrupted

opened with the razor blade knife or with 3.2mm

sutures (8-0, 9-0 or 10-0 nylon) (Fig. 8.17I).

keratome (Fig. 8.17D).

10. Conjunctival flap is reposited and secured by

5. Iridectomy (Fig. 8.17E). A peripheral iridectomy

wet-field cauery.

may be performed by using iris forceps and de

11. Subconjunctival injection of dexamethasone 0.25

Wecker's scissors to prevent postoperative pupil

ml and gentamicin 0.5 ml is given.

block glaucoma.

12. Patching of eye is done with a pad and sticking

6. Methods of lens delivery. In ICCE the lens can be

plaster or a bandage is applied.

delivered by any of the following methods:

i. Indian smith method. Here the lens is delivered

SURGICAL TECHNIQUES OF EXTRA

with tumbling technique by applying pressure on

CAPSULAR CATARACT EXTRACTION FOR

limbus at 6 O'clock position with lens expressor

ADULTHOOD CATARACTS

and counterpressure at 12 O’clock with the lens

The surgical techniques of ECCE can be described

spatula. With this method lower pole is delivered

separately for adulthood cataracts and childhood

first.

cataracts. The surgical techniques of ECCE presently

ii. Cryoextraction. In this technique, cornea is lifted

in vogue for adulthood cataracts include :

up, lens surface is dried with a swab, iris is

Conventional, extracapsular cataract extraction

retracted up and tip of the cryoprobe is applied

on the anterior surface of the lens in the upper

(ECCE),

quadrant. Freezing is activated (-40^oC) to create

Manual small incision cataract surgery (SICS),

adhesions between the lens and the probe. The

and

zonules are ruptured by gentle rotatory

Phacoemulsification.

DISEASES OF THE LENS

189

CONVENTIONAL EXTRACAPSULAR

9. Hydrodissection. After the anterior capsulotomy,

CATARACT EXTRACTION

the balanced salt solution (BSS) is injected under the

peripheral part of the anterior capsule. This

Surgical steps of conventional ECCE are :

manoeuvre separates the corticonuclear mass from

1. Superior rectus (bridle) suture is passed to fix the

the capsule.

eye in downward gaze (Fig. 8.17A).

10. Removal of nucleus. After hydrodissection the

2. Conjunctival flap (fornix based) is prepared to

nucleus can be removed by any of the following

expose the limbus (Fig. 8.17B) and haemostasis is

techniques:

achieved by wet field cautery. Many surgeons do

i. Pressure and counter-pressure method. In it the

not make conjunctival flap.

posterior pressure is applied at

12 O’clock

3. Partial thickness groove or gutter is made through

position with corneal forceps or lens spatula and

about two-thirds depth of anterior limbal area from 10

the nucleus is expressed out by counter-pressure

to 2 O’clock (120^o) with the help of a razor blade knife

exerted at 6 O'clock position with a lens hook

(Fig. 8.17C).

(Fig. 8.18D).

4. Corneoscleral section. The anterior chamber is

ii. Irrigating wire vectis technique. In this method,

opened with the razor blade knife or with 3.2-mm

loop of an irrigating wire vectis is gently passed

below the nucleus, which is then lifted out of the

keratome.

eye.

5. Injection of viscoelastic substance in anterior

11. Aspiration of the cortex. The remaining cortex is

chamber. A viscoelastic substance such as 2%

aspirated out using a two-way irrigation and

methylcellulose or 1% sodium hyaluronate is injected

aspiration cannula (Fig. 8.18E).

into the anterior chamber. This maintains the anterior

12. Implantation of IOL. The PMMA posterior

chamber and protects the endothelium.

chamber IOL is implanted in the capsular bag after

6. Anterior capsulotomy. It can be performed by any

inflating the bag with viscoelastic substance (Figs.

of the following methods:

8.18 G & H).

i. Can-opener's technique. In it, an irrigating

13. Closure of the incision is done by a total of 3 to

cystitome (or simply a 26 gauge needle, bent at

5 interrupted 10-0 nylon sutures or continuous sutures

its tip) is introduced into the anterior chamber

(Fig. 8.18I).

and multiple small radial cuts are made in the

14. Removal of viscoelastic substance. Before tying

anterior capsule for 360^o (Fig. 8.18A).

the last suture the visco-elastic material is aspirated

ii. Linear capsulotomy (Envelope technique). Here

out with 2 way cannula and anterior chamber is filled

a straight incision is made in the anterior capsule

with BSS.

(in the upper part) from 2-10 O'clock position.

15. Conjunctival flap is reposited and secured by

The rest of the capsulotomy is completed in the

wet field cautery.

16. Subconjunctival injection of dexamethasone 0.25

end after removal of nucleus and cortex.

ml and gentamicin 0.5 ml is given.

iii. Continuous circular capsulorrhexis

(CCC).

17. Patching of eye is done with a pad and sticking

Recently this is the most commonly performed

plaster or a bandage is applied.

procedure. In this the anterior capsule is torn in

a circular fashion either with the help of an

MANUAL SMALL INCISION CATARACT

irrigating bent-needle cystitome or with a

SURGERY

capsulorrhexis forceps (Fig. 8.20B).

Manual small incision cataract surgery (SICS) is

7. Removal of anterior capsule. It is removed with

becoming very popular because of its merits over

the help of a Kelman-McPherson forceps (Fig. 8.18B).

conventional ECCE as well as phacoemulsification

8. Completion of corneoscleral section. It is

technique highlighted above. In this technique ECCE

completed from 10 to 2 O’ clock position either with

with intraocular lens implantation is performed

the help of corneo-scleral section enlarging scissors

through a sutureless self-sealing valvular sclero-

or 5.2-mm blunt keratome (Fig. 8.18C).

corneo tunnel incision.

DISEASES OF THE LENS

191

Surgical steps of manual SICS are (Fig. 8.19) :

hydrodissection and completed by rotating the

1. Superior rectus (bridle) suture is passed to fix the

nucleus with Sinskey's hook (Fig. 8.19K).

eye in downward gaze (Fig. 8.19A). This is specifically

ii. Delivery of the nucleus outside through the

corneo-scleral tunnel can be done by any of the

important in manual SICS where in addition to fixation

following methods:

of globe, it also provides a countertraction force

Irrigating wire vectis method (Fig. 8.19L). (It is

during delivery of nucleus and epinucleus.

the most commonly used method).

2. Conjunctival flap and exposure of sclera (Fig.

Blumenthal's technique,

8.19B). A small fornix based conjunctival flap is made

Phacosandwitch technique,

with the help of sharp-tipped scissors along the

Phacofracture technique, and

limbus from 10 to 2 O’clock positions. Conjunctiva

Fishhook technique.

and the Tenon's capsule are dissected, seperated from

9. Aspiration of cortex. The remaining cortex is

the underlying sclera and retracted to expose about 4

aspirated out using a two-way irrigation and

mm strip of sclera along the entire incision length.

aspiration cannula (Fig. 8.19M) from the main incision

3. Haemostasis is achieved by applying gentle and

and/or side port entry.

just adequate wet field cautery.

10. IOL implantation. A posterior chamber IOL is

4. Sclero-corneal tunnel incision. A self-sealing

implanted in the capsular bag after filling the bag with

sclero-corneal tunnel incision is made in manual SICS.

viscoelastic substance (Figs. 8.19N, O & P)

It consists of following components:

11. Removal of viscoelastic material is done

i. External scleral incision. A one-third to half-

thoroughly from the anterior chamber and capsular

thickness external scleral groove is made about

bag with the help of two-way irrigation aspiration

1.5 to 2mm behind the limbus. It varies from 5.5

cannula.

mm to 7.5 mm in length depending upon the

12. Wound closure.The anterior chamber is deepened

hardness of nucleus. It may be straight, frown

with balanced salt solution / Ringer's lactate solution

shaped or chevron in configuration (Figs. 18.19C,

injected through side port entry. This leads to self

D & E).

sealing of the sclero-corneal tunnel incision due to

ii. Sclero-corneal tunnel. It is made with the help of

valve effect. Rarely a single infinity suture may be

a crescent knife. It usually extends 1-1.5 mm into

required to seal the wound. The conjunctival flap is

the clear cornea (Fig. 8.19F).

reposited back and is anchored with the help of wet

iii. Internal corneal incision. It is made with the

field cautery (Fig. 8.19Q).

help of a sharp

3.2 mm angled keratome

PHACOEMULSIFICATION

(Fig. 8.19G).

5. Side-port entry of about 1.5-mm valvular corneal

It is presently the most popular method of

incision is made at 9 o'clock position (Fig. 8.19H).

extracapsular cataract extraction. It differs from the

This helps in aspiration of the sub-incisional cortex

conventional ECCE and manual SICS as follows:

and deepening the anterior chamber at the end of

1. Corneoscleral incision required is very small (3

surgery.

mm). Therefore, sutureless surgery is possible

6. Anterior capsulotomy. As described in

with self-sealing scleral tunnel or clear corneal

conventional ECCE, the capsulotomy in manual SICS

incision made with a 3 mm keratome.

can be either a canopner, or envelope or CCC.

2. Continuous curvilinear capsulorrhexis (CCC) of

However, a large sized CCC is preferred (Fig. 8.19I).

4-6 mm is preferred over other methods of anterior

7. Hydrodissection. As described in ECCE

capsulotomy (Fig. 8.20A).

hydrodissection (Fig. 8.19J) is essential to separate

3. Hydrodissection i.e., separation of capsule from

corticonuclear mass from the posterior capsule in

the cortex by injecting fluid exactly between the

SICS.

two (Fig. 8.20B) is must for phacoemulsification

8. Nuclear management. It consists of following

in SICS. This procedure facilitates nucleus

manoeuvres :

rotation and manipulation during phacoemulsifica-

i. Prolapse of nucleus out of the capsular bag into

tion. Some surgeons also perform hydrodelineation

the anterior chamber is usually initiated during

(Fig. 8.20C).

DISEASES OF THE LENS

193

4. Nucleus is emulsified and aspirated by

The corneo-scleral tunnel techniques (closed

phacoemulsifier. Phacoemulsifier basically acts

chamber surgery) as described for SICS is preferred

through a hollow 1-mm titanium needle which

over the conventional ECCE technique (open chamber

vibrates by piezoelectric crystal in its longitudinal

surgery).

axis at an ultrasonic speed of

40000 times a

Surgical steps of irrigation and aspiration of lens

second and thus emulsifies the nucleus. Many

matter by corneo-scleral tunnel incision

different techniques are being used to accomplish

techniques are as follows :

phacoemulsification. A few common names are

1 to 5 initial steps upto making of side port entry are

‘chip and flip technique’, ‘divide and conquer

similar as described for manual SICS in adults (page

technique’ (Figs. 8.20 D&E) ‘stop and chop’ and

191 Figs. 8.19A to H).

‘phaco chop technique’.

6. Anterior capsulorhexis of about 5mm size is made

5. Remaining cortical lens matter is aspirated with

as described on page 189 (Figs. 8.20A). In children

the help of an irrigation-aspiration technique

the anterior capsule is more elastic than in adults and

(Fig. 8.20F).

therefore, the capsulorhexis may be difficult due to

6. Next steps i.e., IOL implantation, removal of

tendency to run outwards.

viscoelastic substance and wound closure are

7. Irrigation and aspiration of lens matter (which

similar to that of SICS. Foldable IOL is most ideal

is soft in children) can be done by any of the following

with phacoemulsification technique.

methods :

Phakonit. Phakonit refers to the technique of

With two-way irrigation and aspiration Simcoe

phacoemulsification (PHAKO) performed with a

cannula (Fig. 8.19M) or,

needle (N) opening via an incision (I) using the tip

With a phacoprobe (phaco-aspiration) (Fig. 8.20F)

(T) of phacoprobe. In this technique the size of

8. Posterior capsulorhexis of about 3-4 mm size is

incision is only 0.9 mm and after completion of the

recomnended in children to avoid the problem of

operation an ultrathin rollable IOL is inserted into the

posterior capsule opacification.

capsular bag. This technique offers almost nil

9. Anterior vitrectomy of limited amount should be

astigmatism cataract surgery.

performed with a vitrector.

Laser phacoemulsification. This technique is under

10. Implantation of IOL is done in the capsular bag

trial and perhaps may soon replace the conventional

after inflating it with viscoelastic substance (Figs.

phacoemulsification. In it the lens nucleus is

8.19N, O&P). Heparin or fluorine coated PMMA IOLs

emulsified utilizing laser energy. The advantage of

are preferred in children. Some surgeons prefer to

this technique is that the laser energy used to emulsify

capture the lens optic through posterior

cataractous lens is not exposed to other intraocular

capsulorhexis.

structures (c.f. ultrasonic energy).

Note: Steps 8 and 9, and optic capture as described in

step 10 are measures to prevent formation of after

SURGICAL TECHNIQUES OF EXTRACAPSULAR

cataract, the incidence of which is very high in

CATARACT EXTRACTION FOR CHILDHOOD

children.

CATARACT

11. Removal of viscoelastic substance is done with

Surgical techniques employed for childhood cataract

the help of two-way cannula.

are essentially of two types:

12. Wound closure. Though a well constructed

Irrigation and aspiration of lens matter, and

corneo-scleral tunnel often does not require a suture,

Lensectomy

but placement of one horizontal suture (with 10-0

nylon) ensures wound stability and reduces

1. Irrigation and aspiration of lens matter

postoperative astigmatism.

Irrigation and aspiration of lens matter can be done

by:

2. Lensectomy

i. Conventional ECCE technique, or

ii. Corneo-scleral tunnel techniques which include :

In this operation most of the lens including anterior

Manual SICS technique, and

and posterior capsule along with anterior vitreous

Phaco-aspiration technique

are removed with the help of a vitreous cutter, infusion

194

Comprehensive OPHTHALMOLOGY

Fig. 8.20. Surgical steps of phacoemulsification : A, Continuous curvilinear capsulorrhexis; B, Hydrodissection;

C, Hydrodelineation; D&E; Nucleus emulsification by divide and conquer technique (four quadrant cracking);

F, Aspiration of cortex.

and suction machine (Fig. 8.21). Childhood cataracts,

both congenital/developmental and acquired, being

soft are easily dealt with this procedure especially in

very young children (less than 2 years of age) in which

primary IOL implantation is not planned. Lensectomy

in children is performed under general anaesthesia.

Either pars plana or limbal approach may be adopted.

In pars plana approach, the lens is punctured at its

equator and stirred with the help of a Ziegler’s or any

other needle-knife introduced through the sclera and

ciliary body, from a point about 3.5-4 mm behind

the limbus. The cutter (ocutome) of the vitrectomy

machine is introduced after enlarging the sclerotomy

(Fig. 8.22) and lensectomy along with anterior

vitrectomy is completed using cutting, irrigation

and aspiration mechanisms. The aim of modern

lensectomy is to leave in situ a peripheral rim of

capsule as an alternative to complete lensectomy.

Secondary IOL implantation can be planned at a

later date.

Fig. 8.21. Kaufman’s vitrector.

DISEASES OF THE LENS

195

2. Iris-supported lenses. These lenses are fixed on

the iris with the help of sutures, loops or claws.

These lenses are also not very popular due to a

high incidence of postoperative complications.

Example of iris supported lens is Singh and Worst’s

iris claw lens (Figs. 8.24B and 8.25).

3. Posterior chamber lenses. PCIOLs rest entirely

behind the iris (Fig. 8.26). They may be supported by

the ciliary sulcus or the capsular bag. Recent trend is

towards ‘in-the-bag-fixation’. Commonly used model

of PCIOLs is modified C-loop (Fig. 8.24C).

Depending on the material of manufacturing, three

types of PC-IOLs are available :

i. Rigid IOLs. The modern one piece rigid IOLs are

made entirely from PMMA.

ii. Foldable IOLs, to be implanted through a small

Fig. 8.22. Pars plana lensectomy.

incision (3.2 mm) after phacoemulsification are

INTRAOCULAR LENS IMPLANTATION

made of silicone, acrylic, hydrogel and collamer.

iii. Rollable IOLs are ultra thin IOLs. These are

Presently, intraocular lens (IOL) implantation is the

implanted through micro incision (1mm) after

method of choice for correcting aphakia. Its

phakonit technique. These are made of hydrogel.

advantages and disadvantages over spectacles and

contact lenses are described in aphakia (see page

Indications of IOL implantation

31).

Recent trend is to implant an IOL in each and every

The IOL implant history had its beginning on

case being operated for cataract; unless it is

November 29, 1949, when Harold Ridley, a British

contraindicated. However, operation for unilateral

cataract should always be followed by an IOL

ophthalmologist, performed his first case. Since then

implantation.

history of IOLs has always been exciting, often

frustrating and finally rewarding and now highly

developed.

Types of intraocular lenses

During the last two decades a large number of

different types and styles of lenses have been

developed. The commonly used material for their

manufacture is polymethylmethacrylate (PMMA).

The major classes of IOLs based on the method of

fixation in the eye are as follows:

1. Anterior chamber IOL. These lenses lie entirely

in front of the iris and are supported in the angle

of anterior chamber

(Fig.

8.23). ACIOL can be

inserted after ICCE or ECCE. These are not very

popular due to comparatively higher incidence of

bullous keratopathy. When indicated,

‘Kelman

multiflex’

(Fig.

8.24A) type of ACIOL is used

Fig. 8.23. Pseudophakia with Kelman Multiflex anterior

commonly.

chamber intraocular lens implant.

196

Comprehensive OPHTHALMOLOGY

Fig. 8.24. Types of intraocular lenses: A, Kelman multiflex (an anterior chamber IOL); B, Singh & Worst's iris claw lens;

C, posterior chamber IOL - modified C-loop type.

Calculation of IOL power (Biometry)

The most common method of determining IOL power

uses a regression formula called ‘SRK (Sanders,

Retzlaff and Kraff) formula’. The formula is P = A -

2.5L - 0.9K, where:

P is the power of IOL,

A is a constant which is specific for each lens

type.

L is the axial length of the eyeball in mm, which

is determined by A-scan ultrasonography.

K is average corneal curvature, which is

determined by keratometry.

The ultrasound machine equipped with A-scan

and IOL power calculation software is called

Fig. 8.25. Pseudophakia with iris claw intraocular

lens implant.

‘Biometer’.

Fig. 8.26. Pseudophakia with posterior chamber intraocular lens A : As seen on retroillumination with slit-lamp;

B, Diagrammatic depiction of PCIOL implanted in the capsular bag.

DISEASES OF THE LENS

197

Primary versus secondary IOL implantation

5. After 6-8 weeks of operation corneoscleral sutures

Primary IOL implantation refers to the use of IOL

are removed (when applied). Now a days most

during surgery for cataract, while secondary IOL is

surgeons are doing sutureless cataract surgery.

implanted to correct aphakia in a previously operated

6. Final spectacles are prescribed after about 8 weeks

eye.

of operation.

Surgical technique of anterior chamber IOL

COMPLICATIONS OF CATARACT

implantation

SURGERY AND THEIR MANAGEMENT

Anterior chamber IOL implantation can be carried out

Now-a-days cataract surgery is being performed

after ICCE and ECCE. After completion of lens

largely by extracapsular cataract extraction technique.

extraction, the pupil is constricted by injecting miotics

Therefore, complications encountered during these

(1 percent acetylcholine or pilocarpine without

techniques are described in general. Wherever

preservatives) into the anterior chamber. Anterior

necessary a specific reference of the technique viz.

chamber is filled with 2 percent methylcellulose or 1

conventional ECCE, manual SICS and

percent sodium hyaluronate (Healon). The IOL, held

phacoemulsification in relation to the particular

by a forceps, is gently slid into the anterior chamber.

complication is highlighted.

Inferior haptic is pushed in the inferior angle at 6

Complications encountered during surgical

O'clock position and upper haptic is pushed to

engage in the upper angle (Figs. 8.17 G & H).

management of cataract can be enumerated under the

following heads:

Technique of posterior chamber IOL implantation

(A) Preoperative complications

Implantation of rigid intraocular lens. PCIOL is

(B) Intraoperative complications

implanted after ECCE. After completion of ECCE, the

capsular bag and anterior chamber are filled with 2

(D) Delayed (late) postoperative complications

percent methylcellulose or 1 percent sodium

(E) IOL-related complications

hyaluronate. The PCIOL (Fig. 8.24C), is grasped by

the optic with the help of IOL holding forceps. The

[A] Preoperative complications

inferior haptic and optic of IOL is gently inserted into

1. Anxiety. Some patients may develop anxiety, on

the capsular bag behind the iris at 6 O'clock position

the eve of operation due to fear and apprehension of

(Fig. 8.18F). The superior haptic is grasped by its tip,

operation. Anxiolytic drugs such as diazepam 2 to 5

and is gently pushed down and then released to slide

mg at bed time usually alleviate such symptoms.

in the upper part of the capsular bag behind the iris

2. Nausea and gastritis. A few patients may develop

(Fig. 8.18G). The IOL is then dialled into the horizontal

nausea and gastritis due to preoperative medicines

position (Fig. 8.18H).

such as acetazolamide and/or glycerol. Oral antacids

Implantation of foldable IOLs is made either with the

and omission of further dose of such medicines

help of holder-folder forceps or the foldable IOLs

usually relieve the symptoms.

injector.

3. Irritative or allergic conjunctivitis may occur in

some patients due to preoperative topical antibiotic

POSTOPERATIVE MANAGEMENT AFTER

drops. Postponing the operation for 2 days along

CATARACT OPERATION

with withdrawal of such drugs is required.

1. The patient is asked to lie quietly upon the back

4. Corneal abrasion may develop due to inadvertent

for about three hours and advised to take nil

injury during Schiotz tonometry. Patching with

orally.

antibiotic ointment for a day and postponement of

2. For mild to moderate postoperative pain injection

operation for 2 days is required.

diclofenac sodium may be given.

5. Complications due to local anaesthesia

3. Next morning bandage is removed and eye is

Retrobulbar haemorrhage may occur due to

inspected for any postoperative complication.

4. Antibiotic-steroid eyedrops are used for four

retrobulbar block. Immediate pressure bandage

times, three times, two times and then once a day

after instilling one drop of 2% pilocarpine and

for 2 weeks each.

postponement of operation for a week is advised.

198

Comprehensive OPHTHALMOLOGY

Oculocardiac reflex, which manifests as

Premature entry into the anterior chamber

bradycardia and/or cardiac arrhythmia, has also

can occur because of deep dissection

been observed due to retrobulbar block. An

(Fig. 8.27C). Once this is detected, dissection

intravenous injection of atropine is helpful.

in that area should be stopped and a new

Perforation of globe may also occur sometimes.

dissection started at a lesser depth at the

To prevent such catastrophy, gentle injection

other end of the tunnel.

with blunt-tipped needle is recommended. Further,

Scleral disinsertion can occur due to very

peribulbar anaesthesia may be preferred over

deep groove incision. In it there occurs

retrobulbar block.

complete separation of inferior sclera from the

Subconjunctival haemorrhage is a minor

sclera superior to the incision (Fig. 8.27D).

complication observed frequently, and does not

Scleral disinsertion needs to be managed by

need much attention.

radial sutures.

Spontaneous dislocation of lens in vitreous has

also been reported (in patients with weak and

4. Injury to the cornea (Descemet's detachment),

degenerated zonules especially with hypermature

iris and lens may occur when anterior chamber is

cataract) during vigorous ocular massage after

entered with a sharp-tipped instrument such as

retrobulbar block. The operation should be

keratome or a piece of razor blade. A gentle handling

postponed and further management is on the

with proper hypotony reduces the incidence of such

lines of posterior dislocation of lens (page 204).

inadvertent injuries.

5. Iris injury and iridodialysis (tear of iris from root)

[B] Operative complications

may occur inadvertently during intraocular

1. Superior rectus muscle laceration and/or

manipulation.

haematoma, may occur while applying the bridle

6. Complications related to anterior capsulorhexis.

suture. Usually no treatment is required.

2. Excessive bleeding may be encountered during

Continuous curvilinear capsulorhexis (CCC) is the

the preparation of conjunctival flap or during incision

preferred technique for opening the anterior capsule

into the anterior chamber. Bleeding vessels may be

for SICS and phacoemulsification. Following

gently cauterised.

complications may occur:

3. Incision related complications depend upon the

Escaping capsulorhexis i.e., capsulorhexis moves

type of cataract surgery being performed.

peripherally and may extend to the equator or

i. In conventional ECCE there may occur irregular

posterior capsule.

incision. Irregular incision leading to defective

Small capsulorhexis. It predisposes to posterior

coaptation of wound may occur due to blunt

capsular tear and nuclear drop during

cutting instruments.

hydrodissection. It also predisposes to occurrence

ii. In manual SICS and phacoemulsification

of zonular deshiscence. Therefore, a small sized

following complications may occur while making

capsulorhexis should always be enlarged by 2 or

the self-sealing tunnel incision.

3 relaxing incisions before proceeding further.

Button holing of anterior wall of tunnel can

Very large capsulorhexis may cause problems

occur because of superficial dissection of the

for in the bag placement of IOL.

scleral flap (Fig. 8.27B). As a remedy, abandon

this dissection and re-enter at a deeper plane

Eccentric capsulorhexis can lead to IOL

from the other side of the external incision.

decentration at a later stage.

Fig. 8.27. Configuration of sclerocorneal tunnel incision: A, correct incision; B, Buttonholing of anterior wall of the tunnel;

C, Premature entry into the anterior chamber; and D, Scleral disinsertion.

DISEASES OF THE LENS

199

7. Posterior capsular rupture (PCR). It is a dreaded

A meticulously performed partial anterior

complication during extracapsular cataract extraction.

vitrectomy will reduce the incidence of postoperative

In manual SICS and phacoemulsification PCR is even

problems associated with vitreous loss such as

more feared because it can lead to nuclear drop into

updrawn pupil, iris prolapse and vitreous touch

the vitreous. The PCR can occur in following

syndrome.

situations:

10. Nucleus drop into the vitreous cavity. It occurs

During forceful hydrodissection,

more frequently with phacoemulsification, less

By direct injury with some instrument such as

frequently with manual SICS and sparingly with

Sinskey's hook, chopper or phacotip, and

conventional ECCE. It is a dreadful complication which

During cortex aspiration (accidental PCR)

occurs due to sudden and large PCR.

8. Zonular dehiscence may occur in all techniques of

Management. Once the nucleus has dropped into

ECCE but is especially common during nucleus

the vitreous cavity, no attempt should be made to

prolapse into the anterior chamber in manual SICS.

fish it out. The case must be referred to vitreoretinal

9. Vitreous loss: It is the most serious complication

surgeon after a thorough anterior vitrectomy and

which may occur following accidental rupture of

cortical clean up.

posterior capsule during any technique of ECCE.

11. Posterior loss of lens fragments into the vitreous

Therefore, adequate measures as described below

cavity may occur after PCR or zonular dehiscence

should be taken to prevent vitreous loss.

during phacoemulsification. It is potentially serious

To decrease vitreous volume: Preoperative use

because it may result in glaucoma, chronic uveitis,

of hyperosmotic agents like 20 percent mannitol

chronic CME and even retinal detachment.

or oral glycerol is suggested.

Management. The case should be managed by

To decrease aqueous volume: Preoperatively

vitreoretinal surgeon by performing pars plana

acetazolamide 500 mg orally should be used and

vitrectomy and removal of nuclear fragments.

adequate ocular massage should be carried out

12. Expulsive choroidal haemorrhage. It is one of

digitally after injecting local anaesthesia.

the most dramatic and serious complications of

To decrease orbital volume adequate ocular

cataract surgery. It usually occurs in hypertensives

massage and orbital compression by use of

and patients with arteriosclerotic changes. It may

superpinky, Honan's ball, or 30 mm of Hg pressure

occur during operation or during immediate

by paediatric sphygmomanometer should be

postoperative period. Its incidence was high in ICCE

carried out.

and conventional ECCE but has decreased markedly

Better ocular akinesia and anaesthesia decrease

with valvular incision of manual SICS and phaco

the chances of pressure from eye muscle.

emulsification technique.

Minimising the external pressure on eyeball by

It is characterised by spontaneous gaping of the

not using eye speculum, reducing pull on bridle

wound followed by expulsion of the lens, vitreous,

suture and overall gentle handling during surgery.

retina, uvea and finally a gush of bright red blood.

Use of Flieringa ring to prevent collapse of

Although treatment is unsatisfactory, the surgeon

sclera especially in myopic patients decreases

should attempt to drain subchoroidal blood by

the incidence of vitreous loss.

performing an equatorial sclerotomy. Most of the time

When IOP is high in spite of all above measures

eye is lost and so evisceration operation has to be

and operation cannot be postponed, in that

performed.

situation a planned posterior-sclerotomy with

drainage of vitreous from pars plana will prevent

[C] Early postoperative complications

rupture of the anterior hyaloid face and vitreous

1. Hyphaema. Collection of blood in the anterior

loss.

chamber may occur from conjunctival or scleral

Management of vitreous loss. Once the vitreous loss

vessels due to minor ocular trauma or otherwise.

has occurred, the aim should be to clear it from the

Treatment. Most hyphaemas absorb spontaneously

anterior chamber and incision site. This can be

and thus need no treatment. Sometimes hyphaema

achieved by performing partial anterior vitrectomy,

may be large and associated with rise in IOP. In such

with the use of automated vitrectors.

cases, IOP should be lowered by acetazolamide and

200

Comprehensive OPHTHALMOLOGY

hyperosmotic agents. If the blood does not get

iii. Pupil block due to vitreous bulge after ICCE

absorbed in a week’s time, then a paracentesis should

leads to formation of iris bombe and shallowing

be done to drain the blood.

of anterior chamber. If the condition persists for

2. Iris prolapse. It is usually caused by inadequate

5-7 days, permanent peripheral anterior synechiae

suturing of the incision after ICCE and conventional

(PAS) may be formed leading to secondary angle

ECCE and occurs during first or second postoperative

closure glaucoma.

day. This complication is not known with manual SICS

Pupil block is managed initially with mydriatic,

and phacoemulsification technique.

hyperosmotic agents (e.g., 20% mannitol) and

Management: A small prolapse of less than 24 hours

acetazolamide. If not relieved, then laser or surgical

duration may be reposited back and wound sutured.

peripheral iridectomy should be performed to bypass

A large prolapse of long duration needs abscission

the pupillary block.

and suturing of wound.

5. Postoperative anterior uveitis can be induced by

3. Striate keratopathy. Characterised by mild corneal

instrumental trauma, undue handling of uveal tissue,

reaction to residual cortex or chemical reaction

oedema with Descemet’s folds is a common

induced by viscoelastics, pilocarpine etc.

complication observed during immediate

Management includes more aggressive use of topical

postoperative period. This occurs due to endothelial

steroids, cycloplegics and NSAIDs. Rarely systemic

damage during surgery.

steroids may be required in cases with severe

Management. Mild striate keratopathy usually

fibrinous reaction.

disappears spontaneously within a week. Moderate

6. Bacterial endophthalmitis. This is one of the most

to severe keratopathy may be treated by instillation

dreaded complications with an incidence of 0.2 to 0.5

of hypertonic saline drops (5% sodium chloride) along

percent. The principal sources of infection are

with steroids.

contaminated solutions, instruments, surgeon's

4. Flat (shallow or nonformed) anterior chamber.

hands, patient's own flora from conjunctiva, eyelids

It has become a relatively rare complication due to

and air-borne bacteria.

improved wound closure. It may be due to wound

Symptoms and signs of bacterial endophthalmitis are

leak, ciliochoroidal detachment or pupil block.

generally present between 48 and 72 hours after

i. Flat anterior chamber with wound leak is

surgery and include: ocular pain, diminshed vision,

associated with hypotony. It is diagnosed by

lid oedema, conjunctival chemosis and marked

Seidel's test. In this test, a drop of fluorescein is

circumciliary congestion, corneal oedema, exudates

instilled into the lower fornix and patient is asked

in pupillary area, hypopyon and diminished or absent

to blink to spread the dye evenly. The incision is

red pupillary glow.

then examined with slit lamp using cobalt-blue

Management. It is an emergency and should be

filter. At the site of leakage, fluorescein will be

managed energetically (see page 152).

diluted by aqueous. In most cases wound leak is

[D] Late postoperative complications

cured within 4 days with pressure bandage and

These complications may occur after weeks, months

oral acetazolamide. If the condition persists,

or years of cataract surgery.

injection of air in the anterior chamber and

1. Cystoid macular oedema (CME). Collection of

resuturing of the leaking wound should be carried

fluid in the form of cystic loculi in the Henle’s layer of

out.

macula is a frequent complication of cataract surgery.

ii. Ciliochoroidal detachment. It may or may not be

However, in most cases it is clinically insignificant,

associated with wound leak. Detached cilio-

does not produce any visual problem and undergoes

choroid presents as a convex brownish mass in

spontaneous regression. In few cases, clinically

the involved quadrant with shallow anterior

significant CME typically produces visual diminution

chamber. In most cases choroidal detachment is

one to three months after cataract extraction. On

cured within 4 days with pressure bandage and

funduscopy it gives honeycomb appearance. On

use of oral acetazolamide. If the condition

fluorescein angiography it depicts typical flower

persists, suprachoroidal drainage with injection

petal pattern due to leakage of dye from perifoveal

of air in the anterior chamber is indicated.

capillaries.

DISEASES OF THE LENS

201

In most cases it is associated with vitreous

5. Epithelial ingrowth. Rarely conjunctival epithelial

incarceration in the wound and mild iritis. Role of

cells may invade the anterior chamber through a

some prostaglandins is being widely considered in

defect in the incision. This abnormal epithelial

its etiopathogenesis. Therefore, immediate preopera-

membrane slowly grows and lines the back of cornea

tive and postoperative use of antiprostaglandins

and trabecular meshwork leading to intractable

(indomethacin or flurbiprofen or ketorolac) eyedrops

glaucoma. In late stages, the epithelial membrane

is recommended as prophylaxis of CME.

extends on the iris and anterior part of the vitreous.

6. Fibrous downgrowth into the anterior chamber ay

In cases of CME with vitreous incarceration,

occur very rarely when the cataract wound apposition

anterior vitrectomy along with steroids and

is not perfect. It may cause secondary glaucoma,

antiprostaglandins may improve visual acuity and

disorganisation of anterior segment and ultimately

decrease the amount of discomfort.

phthisis bulbi.

2. Delayed chronic postoperative endophthalmitis

7. After cataract. It is also known as ‘secondary

is caused when an organism of low virulence

cataract’. It is the opacity which persists or develops

(Propionobacterium acne or staph epidermidis)

after extracapsular lens extraction.

becomes trapped within the capsular bag. It has an

Causes. (i) Residual opaque lens matter may persist

onset ranging from 4 weeks to years (mean 9 months)

as after cataract when it is imprisoned between the

postoperatively and typically follows an uneventful

remains of the anterior and posterior capsule,

cataract extraction with a PCIOL in the bag.

surrounded by fibrin (following iritis) or blood

3. Pseudophakic bullous keratopathy (PBK) is

(following hyphaema). (ii) Proliferative type of after

usually a continuation of postoperative corneal

cataract may develop from the left-out anterior

oedema produced by surgical or chemical insult to a

epithelial cells. The proliferative hyaline bands may

healthy or compromised corneal endothelium. PBK is

sweep across the whole posterior capsule.

becoming a common indication of penetrating

Clinical types. After cataract may present as

keratoplasly (PK).

thickened posterior capsule, or dense membranous

4. Retinal detachment (RD). Incidence of retinal

after cataract (Fig. 8.28A) or Soemmering’s ring which

detachment is higher in aphakic patients as compared

refers to a thick ring of after cataract formed behind

to phakics. It has been noted that retinal detachment

the iris, enclosed between the two layers of capsule

is more common after ICCE than after ECCE. Other

(Fig. 8.28B) or Elschnig’s pearls in which the

risk factors for aphakic retinal detachment include

vacuolated subcapsular epithelial cells are clustered

vitreous loss during operation, associated myopia

like soap bubbles along the posterior capsule

and lattice degeneration of the retina.

(Fig. 8.28C).

Fig. 8.28. Types of after cataract : A, dense membranous; B, Soemmering's ring; C, Elschnig's pearls.

202

Comprehensive OPHTHALMOLOGY

Treatment is as follows :

Sun-set syndrome (Inferior subluxation of IOL).

i. Thin membranous after cataract and thickened

Sun-rise syndrome (Superior subluxation of IOL).

posterior capsule are best treated by YAG-laser

Lost lens syndrome refers to complete dislocation

capsulotomy or discission with cystitome or

of an IOL into the vitreous cavity.

Zeigler’s knife.

Windshield wiper syndrome. It results when a

ii. Dense membranous after cataract needs surgical

very small IOL is placed vertically in the sulcus.

membranectomy.

In it the superior loop moves to the left and right,

iii. Soemmering’s ring after cataract with clean central

with movements of the head.

posterior capsule needs no treatment.

3. Pupillary capture of the IOL may occur following

iv. Elschnig’s pearls involving the central part of

postoperative iritis or proliferation of the remains of

the posterior capsule can be treated by YAG-

lens fibres.

laser capsulotomy or discission with cystitome.

4. Toxic lens syndrome. It is the uveal inflammation

7. Glaucoma-in-aphakia and pseudophakia (see

excited by either the ethylene gas used for sterilising

page 234).

IOLs (in early cases) or by the lens material (in late

cases).

[E] IOL-related complications

In addition to the complications of cataract surgery,

following IOL-related complications may be seen:

DISPLACEMENTS OF THE LENS

1. Complications like cystoid macular oedema,

Displacement of the lens from its normal position (in

corneal endothelial damage, uveitis and secondary

patellar fossa) results from partial or complete rupture

glaucoma are seen more frequently with IOL

of the lens zonules.

implantation, especially with anterior chamber and

iris supported IOLs.

CLINICO-ETIOLOGICAL TYPES

UGH syndrome refers to concurrent occurrence

I. Congenital displacements

of uveitis, glaucoma and hyphaema. It used to

occur with rigid anterior chamber IOLs, which are

These may occur in the following forms:

not used now.

(a) Simple ectopia lentis. In this condition

2. Malpositions of IOL (Fig. 8.29). These may be in

displacement is bilaterally symmetrical and usually

the form of decentration, subluxation and dislocation.

upwards. It is transmitted by autosomal dominant

The fancy names attached to various malpositions of

inheritance.

IOL are:

(b) Ectopia lentis et pupillae. It is characterised by

displacement of the lens associated with slit-shaped

pupil which is displaced in the opposite direction.

Other associations may be cataract, glaucoma and

retinal detachment.

features of some common conditions are as follows:

1. Marfan’s syndrome. It is an autosomal dominant

mesodermal dysplasia. In this condition lens is

displaced upwards and temporally (bilaterally

symmetrical) (Fig. 8.30). Systemic anomalies include

arachnodactyly (spider fingers), long extremities,

hyperextensibility of joints, high arched palate and

dissecting aortic aneurysm.

2. Homocystinuria. It is an autosomal recessive,

inborn error of metabolism. In it the lens is usually

subluxated downwards and nasally.

Systemic features are fair complexion, malar flush,

Fig. 8.29. Decentered IOL.

mental retardation, fits and poor motor control.

DISEASES OF THE LENS

203

6. Stickler syndrome. Ectopia lentis is occasionally

associated in this condition (details see page 270).

7. Sulphite oxidase deficiency. It is a very rare

autosomal recessive disorder of sulphur metabolism.

Ectopia lentis is a universal ocular feature. The

systemic features include progressive muscular

rigidity, decerebrate posture, and mental handicap. It

is a fatal disease, death usually occurs before 5 years

of age.

II. Traumatic displacement of the lens

It is usually associated with concussion injuries.

Fig. 8.30. Subluxated IOL in Marfan's syndrome.

Couching is an iatrogenic posterior dislocation of

lens performed as a treatment of cataract in olden

Diagnosis is established by detecting

days.

homocystine in urine by sodium nitro-prusside

test.

III. Consecutive or spontaneous displacement

3. Weil-Marchesani syndrome. It is condition of

It results from intraocular diseases giving rise to

autosomal recessive mesodermal dysplasia. Ocular

mechanical stretching, inflammatory disintegration or

features are spherophakia, and forward subluxation

degeneration of the zonules. A few common

of lens which may cause pupil block glaucoma.

conditions associated with consecutive displace-

Systemic features are short stature, stubby fingers

ments are: hypermature cataract, buphthalmos, high

and mental retardation.

myopia, staphyloma, intraocular tumours and uveitis.

4. Ehlers-Danlos syndrome. In it the ocular features

are subluxation of lens and blue sclera. The systemic

TOPOGRAPHICAL TYPES

features include hyperextensibility of joints and loose

Topographically, displacements of the lens may be

skin with folds.

classified as subluxation and luxation or dislocation.

5. Hyperlysinaemia. It is an autsomal recessive

inborne error of metabolism occurring due to

I. Subluxation

deficiency of the enzyme lysin alphaketoglutarate

It is partial displacement in which lens is moved

reductase. It is an extremely rare condition

sideways (up, down, medially or laterally), but remains

occasionally associated with ectopia lentis. Systemic

behind the pupil. It results from partial rupture or

features include lax ligaments, hypotonic muscles,

unequal stretching of the zonules (Fig. 8.30 and

seizures and mental handicap.

8.31A).

Fig. 8.31. Displacements of lens: A, subluxation; B, anterior dislocation; C, posterior dislocation.

204

Comprehensive OPHTHALMOLOGY

Clinical feautres are as follows

CONGENITAL ANOMALIES

Defective vision occurs due to marked astigmatism

OF THE LENS

or lenticular myopia.

Uniocular diplopia may result from partial

Coloboma of the lens. It is seen as a notch in

aphakia.

the lower quadrant of the equator (Fig. 8.32). It is

Anterior chamber becomes deep and irregular.

usually unilateral and often hereditary.

Iridodonesis is usually present.

Congenital ectopia lentis (see lens displacement

Dark edge of the subluxated lens is seen on

page 202).

distant direct ophthalmoscopy

Complications of subluxated lens include :

Lenticonus. It refers to cone-shaped elevation of

Complete dislocation,

the anterior pole (lenticonus anterior, Fig. 8.33) or

Cataractous changes,

posterior pole (lenticonus posterior) of the lens.

Uveitis and

Lenticonus anterior may occur in Alport's

Secondary glaucoma.

syndrome and lenticonus posterior in Lowe's

Management. Spectacles or contact lens correction

syndrome. On distant direct ophthalmoscopy,

for phakic or aphakic area (whichever is better) is

both present as an oil globule lying in the centre

helpful in many cases. Surgery is controversial and

of the red reflex. Slit-lamp examination confirms

usually associated with high risk of retinal

the diagnosis.

detachment. Lensectomy with anterior vitrectomy

may be performed in desperate cases.

Congenital cataract. (see page 170).

Microspherophakia. In this condition, the lens is

II. Dislocation or luxation of the lens

spherical in shape (instead of normal biconvex)

In it all the zonules are severed from the lens. A

and small in size. Microspherophakia may occur

dislocated lens may be incarcerated into the pupil or

as an isolated familial condition or as a feature of

present in the anterior chamber (Fig. 8.31B), the

other syndromes e.g., Weil-Marchesani or

vitreous (Fig. 8.31C) (where it may be floating - lens

Marfan’s syndrome.

nutans; or fixed to retina - lens fixata), sub-retinal

space, subscleral space or extruded out of the globe,

partially or completely.

Clinical features of posterior dislocation. These

include: deep anterior chamber, aphakia in pupillary

area, and iridodonesis. Ophthalmoscopic examination

reveals lens in the vitreous cavity.

Clinical features of anterior dislocation are deep

anterior chamber and presence of lens in the anterior

chamber. Clear lens looks like an oil drop in the

aqueous.

Complications associated with dislocated lens are

uveitis and secondary glaucoma.

Management. A lens dislocated in the anterior

chamber and that incarcerated in the pupil should be

removed as early as possible. A dislocated lens from

the vitreous cavity should be removed only if it is

causing uveitis or glaucoma. From the vitreous cavity

lens can be removed after total vitrectomy, either with

the help of an insulated vitreous cryoprobe or by

aspiration facility of vitrectomy probe (only soft

Fig. 8.32.

Fig. 8.33.

Coloboma of the lens.

Lenticonus anterior.

cataract).

CHAPTER

Glaucoma

ANATOMY AND PHYSIOLOGY

PRIMARY OPEN-ANGLE GLAUCOMA AND

RELATED CONDITIONS

Applied anatomy

Primary open-angle glaucoma

Applied physiology

Ocular hypertension

Normal tension glaucoma

GENERAL CONSIDERATIONS

Definition and classification of glaucoma

PRIMARY ANGLE-CLOSURE GLAUCOMA

Pathogenesis of glaucomatous ocular

Latent glaucoma

damage

Intermittent glaucoma

Acute congestive glaucoma

CONGENITAL GLAUCOMAS

Postcongestive angle-closure glaucoma

Terminology

Chronic closed angle glaucoma

Absolute glaucoma

Primary developmental glaucoma

Developmental glaucoma with

SECONDARY GLAUCOMAS

associated anomalies

SURGICAL PROCEDURES FOR GLAUCOMA

be visualised by gonioscopic examination (see page

ANATOMY AND PHYSIOLOGY

546).

Gonioscopic grading of the angle width. Various

APPLIED ANATOMY

systems have been suggested to grade angle width.

Pathophysiology of glaucoma revolves around the

The most commonly used Shaffer’s system of grading

aqueous humour dynamics. The principal ocular

the angle is given in Table 9.1 and is shown in

structures concerned with it are ciliary body, angle of

Fig. 9.2.

anterior chamber and the aqueous outflow system.

Ciliary body

It is the seat of aqueous production. Applied aspects

of its anatomy have been described on page

Angle of anterior chamber

Angle of anterior chamber plays an important role in

the process of aqueous drainage. It is formed by root

of iris, anterior-most part of ciliary body, scleral spur,

trabecular meshwork and Schwalbe’s line (prominent

end of Descemet’s membrane of cornea) (Fig. 9.1).

The angle width varies in different individuals and

plays a vital role in the pathomechanism of different

Fig. 9.1. Section of the anterior ocular structures showing

types of glaucoma. Clinically the angle structures can

region of the anterior chamber.

206

Comprehensive OPHTHALMOLOGY

Table 9.1. Shaffer’s system of grading the angle width

Grade

Angle width

Configuration

Chances of closure

Structures visible on gonioscopy

35-45^o

Wide open

Nil

SL, TM, SS, CBB

III

20-35^o

Open angle

Nil

SL, TM, SS

20^o

Moderately narrow

Possible

SL, TM

10^o

Very narrow

High

SL only

0^o

Closed

None of the angle structures visible

SL = Schwalbe’s line, TM = Trabecular meshwork, SS = Scleral spur, CBB = Ciliary body band

Fig. 9.2. Diagrammatic depiction of various angle structures (SL, Schwalbe's line; TM, trabecular meshwork; SS, scleral

spur; CBB, ciliary body band; ROI, root of iris) as seen in different grades of angle width (Schaffer's grading

system): A, Gonioscopic view; B, Configuration of the angle in cross section of the anterior chamber.

Aqueous outflow system

It includes the trabecular meshwork, Schlemm’s canal,

collector channels, aqueous veins and the episcleral

veins (Fig. 9.3A).

1. Trabecular meshwork.It is a sieve-like structure

through which aqueous humour leaves the eye. It

consists of three portions.

i. Uveal meshwork. It is the innermost part of

trabecular meshwork and extends from the iris

root and ciliary body to the Schwalbe's line. The

arrangement of uveal trabecular bands create

openings of about 25 m to 75 m.

ii. Corneoscleral meshwork. It forms the larger

Fig. 9.3.A The aqueous outflow system.

middle portion which extends from the scleral

spur to the lateral wall of the scleral sulcus. It

either side by endothelium. This narrow part of

consists of sheets of trabeculae that are perforated

trabeculum connects the corneoscleral meshwork

by elliptical openings which are smaller than

with Schlemm’s canal. In fact the outer endothelial

those in the uveal meshwork (5 µ-50 µ).

layer of juxtacanalicular meshwork comprises the

iii Juxtacanalicular

(endothelial) meshwork. It

inner wall of Schlemm’s canal. This part of

forms the outermost portion of meshwork and

trabecular meshwork mainly offers the normal

consists of a layer of connective tissue lined on

resistance to aqueous outflow.

GLAUCOMA

207

2. Schlemm’s canal. This is an endothelial lined oval

acid (7.4), inositol (0.1), Na⁺ (144), K⁺ (4.5), Cl^—

channel present circumferentially in the scleral sulcus.

(10), and HCO_3— (34).

The endothelial cells of its inner wall are irregular,

Oxygen is present in aqueous in dissolved state.

spindle-shaped and contain giant vacuoles. The outer

Note: Thus, composition of aqueous is similar to

wall of the canal is lined by smooth flat cells and

plasma except that it has:

contains the openings of collector channels.

High concentrations of ascorbate, pyruvate and

3. Collector channels. These, also called intra-

lactate; and

scleral aqueous vessels, are about 25-35 in number

Low concentration of protein, urea and glucose.

and leave the Schlemm’s canal at oblique angles to

Aqueous humour: anterior chamber versus posterior

terminate into episcleral veins in a laminated fashion.

chamber. The composition of aqeuous humour in

These intrascleral aqueous vessels can be divided

anterior chamber differs from that of the aqueous

into two systems (Fig. 9.3A). The larger vessels

humour in posterior chamber because of metabolic

(aqueous veins) run a short intrascleral course and

interchange. The main differences are :

terminate directly into episcleral veins (direct system).

HCO_3— in posterior chamber aqueous is higher

Many smaller collector channels form an intrascleral

than in the anterior chamber.

plexus before eventually going into episcleral veins

Cl^— concentration in posterior chamber is lower

(indirect system).

than in the anterior chamber.

Ascorbate concentration of posterior aqueous is

APPLIED PHYSIOLOGY

slightly higher than that of anterior chamber

The physiological processes concerned with the

aqueous.

dynamics of aqueous humour are its production,

Production. Aqueous humour is derived from plasma

drainage and maintenance of intraocular pressure.

within the capillary network of ciliary processes. The

normal aqueous production rate is 2.3 µl/min. The

Aqueous humour and its production

three mechanisms diffusion, ultrafiltration and

Volume. The aqueous humour is a clear watery fluid

secretion (active transport) play a part in its

filling the anterior chamber (0.25 ml) and posterior

production at different levels. The steps involved in

chamber (0.06 ml) of the eyeball.

the process of production are summarized below:

Functions of aqueous humour are:

1. Ultrafiltration. First of all, by ultrafiltration, most

It maintains a proper intraocular pressure.

of the plasma substances pass out from the

It plays an important metabolic role by providing

capillary wall, loose connective tissue and

substrates and by removing metabolites from the

pigment epithelium of the ciliary processes. Thus,

avascular cornea and lens.

the plasma filtrate accumulates behind the non-

It maintains optical transparency.

pigment epithelium of ciliary processes.

It takes the place of lymph that is absent within

2. Secretion. The tight junctions between the cells

the eyeball.

of the non-pigment epithelium create part of blood

Refractive index of aqueous humour is 1.336.

aqueous barrier. Certain substances are actively

Composition. Constituents of normal aqueous

transported (secreted) across this barrier into the

humour are on :.

posterior chamber. The active transport is brought

Water 99.9 and solids 0.1% which include :

about by Na⁺-K⁺ activated ATPase pump and

Proteins

(colloid content). Because of blood

carbonic anhydrase enzyme system. Substances

aqueous barrier the protein content of aqueous

that are actively transported include sodium,

humour (5-16 mg%) is much less than that of

chlorides, potassium, ascorbic acid, amino acids

plasma (6-7 gm%). However, in inflammation of

and bicarbonates.

uvea (iridocyclitis) the blood-aqueous barrier is

3. Diffusion. Active transport of these substances

broken and the protein content of aqueous is

across the non-pigmented ciliary epithelium results

increased (plasmoid aqueous).

in an osmotic gradient leading to the movement

Amino acid constituent of aqueous humour is

of other plasma constituents into the posterior

about 5 mg/kg water.

chamber by ultrafiltration and diffusion. Sodium

Non-colloid constituents in millimols /kg water

is primarily responsible for the movement of water

are glucose (6.0), urea (7), ascorbate (0.9), lactic

into the posterior chamber.

208

Comprehensive OPHTHALMOLOGY

Control of aqueous formation. The diurnal variation

Maintenance of intraocular pressure

in intraocular pressure certainly indicates that some

The intraocular pressure (IOP) refers to the pressure

endogenous factors do influence the aqueous

exerted by intraocular fluids on the coats of the

formation. The exact role of such factors is yet to be

eyeball. The normal IOP varies between 10 and 21 mm

clearly understood. Vasopressin and adenyl-cyclase

of Hg (mean 16 ± 2.5 mm of Hg). The normal level of

have been described to affect aqueous formation by

IOP is essentially maintained by a dynamic

influencing active transport of sodium.

equilibrium between the formation and outflow of the

Ultrafiltration and diffusion, the passive

aqueous humour. Various factors influencing

mechanisms of aqueous formation, are dependent on

intraocular pressure can be grouped as under:

the level of blood pressure in the ciliary capillaries,

(A) Local factors

the plasma osmotic pressure and the level of

Rate of aqueous formation influences IOP levels.

intraocular pressure.

The aqueous formation in turn depends upon

Drainage of aqueous humour

many factors such as permeability of ciliary

Aqueous humour flows from the posterior chamber

capillaries and osmotic pressure of the blood.

into the anterior chamber through the pupil against

Resistance to aqueous outflow (drainage). From

slight physiologic resistance. From the anterior

clinical point of view, this is the most important

chamber the aqueous is drained out by two routes

factor. Most of the resistance to aqueous outflow

(Fig. 9.3B):

is at the level of trabecular meshwork.

1. Trabecular (conventional) outflow. Trabecular

Increased episcleral venous pressure may result

meshwork is the main outlet for aqueous from the

in rise of IOP. The Valsalva manoeuvre causes

anterior chamber. Approximately 90 percent of the

temporary increase in episcleral venous pressure

total aqueous is drained out via this route.

and rise in IOP.

Free flow of aqueous occurs from trabecular

meshwork up to inner wall of Schlemm's canal which

appears to provide some resistance to outflow.

Mechanism of aqueous transport across inner wall

of Schlemm’s canal. It is partially understood.

Vacuolation theory is the most accepted view.

According to it, transcellular spaces exist in the

endothelial cells forming inner wall of Schlemm's

canal. These open as a system of vacuoles and pores,

primarily in response to pressure, and transport the

aqueous from the juxtacanalicular connective tissue

to Schlemm’s canal (Fig. 9.4).

From Schlemm's canal the aqueous is transported

via 25-35 external collector channels into the episcleral

veins by direct and indirect systems (Fig. 9.3A). A

pressure gradient between intraocular pressure and

intrascleral venous pressure (about 10 mm of Hg) is

responsible for unidirectional flow of aqueous.

2. Uveoscleral (unconventional) outlow. It is

responsible for about 10 percent of the total aqueous

outflow. Aqueous passes across the ciliary body into

the suprachoroidal space and is drained by the

venous circulation in the ciliary body, choroid and

sclera.

The drainage of aqueous humour is summarized in

Fig. 9.3.B Flow chart depicting drainage of aqueous

the flowchart (Fig. 9.3B).

humour

210

Comprehensive OPHTHALMOLOGY

4. Dilatation of pupil in patients with narrow

not invariably with raised intraocular pressure (IOP).

anterior chamber angle may cause rise of IOP

Thus, IOP is the most common risk factor but not the

owing to a relative obstruction of the aqeuous

only risk factor for development of glaucoma.

drainage by the iris.

Consequently the term ‘ocular hypertension’ is used

for cases having constantly raised IOP without any

(B) General factors

associated glaucomatous damage. Conversely, the

Heredity. It influences IOP, possibly by

term normal or low tension glaucoma (NTG/LTG) is

multifactorial modes.

suggested for the typical cupping of the disc and/or

Age. The mean IOP increases after the age of 40

visual field defects associated with a normal or low

years, possibly due to reduced facility of aqueous

IOP.

outflow.

Sex. IOP is equal between the sexes in ages 20-

Classification

40 years. In older age groups increase in mean

Clinico-etiologically glaucoma may be classified as

IOP with age is greater in females.

follows:

Diurnal variation of IOP. Usually, there is a

(A) Congenital and developmental glaucomas

tendency of higher IOP in the morning and lower

1. Primary congenital glaucoma (without associated

in the evening (Fig. 9.7). This has been related to

anomalies).

diurnal variation in the levels of plasma cortisol.

2. Developmental glaucoma

(with associated

Normal eyes have a smaller fluctuation (< 5 mm

anomalies).

of Hg) than glaucomatous eyes (> 8 mm of Hg).

(B) Primary adult glaucomas

Postural variations. IOP increases when

1. Primary open angle glaucomas (POAG)

changing from the sitting to the supine position.

2. Primary angle closure glaucoma (PACG)

Blood pressure. As such it does not have long-

3. Primary mixed mechanism glaucoma

term effect on IOP. However, prevalence of

glaucoma is marginally more in hypertensives

than the normotensives.

PATHOGENESIS OF GLAUCOMATOUS OCULAR

Osmotic pressure of blood. An increase in plasma

DAMAGE

osmolarity (as occurs after intravenous mannitol, oral

As mentioned in definition, all glaucomas (classified

glycerol or in patients with uraemia) is associated

above and described later) are characterized by a

with a fall in IOP, while a reduction in plasma

progressive optic neuropathy. It has now been

osmolarity (as occurs with water drinking

recognized that progressive optic neuropathy results

provocative tests) is associated with a rise in IOP.

from the death of retinal ganglion cells (RGCs) in a

General anaesthetics and many other drugs also

typical pattern which results in characteristic optic

influence IOP e.g., alcohol lowers IOP, tobacco

disc appearance and specific visual field defects.

smoking, caffeine and steroids may cause rise in

IOP. In addition there are many antiglaucoma

Pathogenesis of retinal ganglion cell death

drugs which lower IOP.

Retinal ganglion cell (RGC) death is initiated when

some pathologic event blocks the transport of growth

GENERAL CONSIDERATIONS

factors (neurotrophins) from the brain to the RGCs.

The blockage of these neurotrophins initiate a

DEFINITION AND CLASSIFICATION OF

damaging cascade, and the cell is unable to maintain

GLAUCOMA

its normal function. The RGCs losing their ability to

Definition

maintain normal function undergo apoptosis and also

Glaucoma is not a single disease process but a group

trigger apoptosis of adjacent cells. Apoptosis is a

of disorders characterized by a progressive optic

genetically controlled cell suicide programme whereby

neuropathy resulting in a characterstic appearance

irreversibaly damaged cells die, and are subsequently

of the optic disc and a specific pattern of irreversible

engulfed by neighbouring cells, without eliciting any

visual field defects that are associated frequently but

inflammatory response.

GLAUCOMA

211

Retinal ganglion cell death is, of course, associated

B. Secondary insults (Excitotoxicity theory)

with loss of retinal nerve fibres. As the loss of nerve

Neuronal degeneration is believed to be driven by

fibres extends beyond the normal physiological

toxic factors such as glutamate (excitatory toxin),

overlap of functional zones. The characteristic optic

oxygen free radicals, or nitric oxide which are released

disc changes and specific visual field defects become

when RGCs undergo death due to primary insults. In

apparent over the time.

this way the secondary insult leads to continued

damage mediated apoptosis, even after the primary

Etiological factors

insult has been controlled.

Factors involved in the etiology of retinal ganglion

cell death and thus in the etiology of glaucomatous

optic neuropathy can be grouped as below:

CONGENITAL / DEVELOPMENTAL

A. Primary insults

GLAUCOMAS

1. Raised intraocular pressure (Mechanical theory).

Raised intraocular pressure causes mechanical stretch

TERMINOLOGY

on the lamina cribrosa leading to axonal deformation

The congenital glaucomas are a group of diverse

and ischaemia by altering capillary blood flow. As a

disorders in which abnormal high intraocular pressure

result of this, neurotrophins (growth factors) are not

able to reach the retinal ganglion cell bodies in

results due to developmental abnormalities of the

sufficient amount needed for their survival.

angle of anterior chamber obstructing the drainage

2. Pressure independent factors

(Vascular

of aqueous humour. Sometimes glaucoma may not

insufficiency theory). Factors affecting vascular

occur until several years after birth; therefore, the

perfusion of optic nerve head in the absence of raised

term developmental glaucoma is preferred to describe

IOP have been implicated in the glaucomatous optic

such disorders.

neuropathy in patients with normal tension glaucoma

Types

(NTG). However, these may be the additional factors

in cases of raised IOP as well. These factors include:

1. Primary developmental/congenital glaucoma.

Failure of autoregulatory mechanism of blood

2. Developmental glaucoma with associated ocular

flow. The retina and optic nerve share a peculiar

anomalies.

mechanism of autoregulation of blood flow with

rest of the central nervous system. Once the

PRIMARY DEVELOPMENTAL/CONGENITAL

autoregulatory mechanisms are compromised,

GLAUCOMA

blood flow may not be adequate beyond some

It refers to abnormally high IOP which results due to

critical range of IOP (which may be raised or in

developmental anomaly of the angle of the anterior

normal range).

chamber, not associated with any other ocular or

ii.

Vasospasm is another mechanism affecting

systemic anomaly. Depending upon the age of onset

vascular perfusion of optic nerve head. This

the developmental glaucomas are termed as follows:

hypothesis gets credence from the convincing

association between NTG and vasospastic

1. True congenital glaucoma is labelled when IOP is

disorders (migranous headache and Raynaud's

raised during intrauterine life and child is born with

phenomenon).

ocular enlargement. It occurs in about 40 percent of

iii. Systemic hypotension particularly nocturnal dips

cases.

in patients with night time administration of

2. Infantile glaucoma is labelled when the disease

antihypertensive drugs has been implicated for

manifests prior to the child's third birthday. It occurs

low vascular perfusion of optic nerve head

in about 50 percent of cases.

resulting in NTG.

3. Juvenile glaucoma is labelled in the rest 10 percent

iv. Other factors such as acute blood loss and

of cases who develop pressure rise between 3-16

abnormal coagulability profile have also been

years of life.

associated with NTG.

212

Comprehensive OPHTHALMOLOGY

When the disease manifests prior to age of 3 years,

i. Corneal oedema. It is frequently the first sign

the eyeball enlarges and so the term‘buphthalmos’

which arouses suspicion. At first it is epithelial,

(bull-like eyes) is used. As it results due to retention

but later there is stromal involvement and

of aqueous humour (watery solution), the term

permanent opacities may occur.

‘hydrophthalmos, has also been suggested.

ii. Corneal enlargement. It occurs along with

enlargement of globe-buphthalmos

(Fig.

9.5),

Prevalence and genetic pattern

especially when the onset is before the age of 3

Most cases are sporadic. About 10 percent cases

years. Normal infant cornea measures 10.5 mm. A

exhibit an autosomal recessive inheritance with

diameter of more than

13 mm confirms

incomplete peneterance.

enlargement. Prognosis is usually poor in infants

Although sex linkage is not common in

with corneal diameter of more than 16 mm.

inheritance, over 65 percent of the patients are

iii. Tears and breaks in Descemet’s membrane

boys.

(Haab’s striae). These occur because Descemet’s

The disease is bilateral in 75 percent cases, though

membrane is less elastic than the corneal stroma.

the involvement may be asymmetric.

Tears are usually peripheral and concentric with

The disease affects only 1 child in 10,000 births.

the limbus.

3. Sclera becomes thin and appears blue due to

Pathogenesis

underlying uveal tissue.

Maldevelopment of trabeculum including the

4. Anterior chamber becomes deep.

iridotrabecular junction (trabeculodysgenesis) is

5. Iris may show iridodonesis and atrophic patches

responsible for impaired aqueous outflow resulting

in late stage.

in raised IOP. In primary congenital glaucoma the

6. Lens becomes flat due to stretching of zonules and

trabeculodysgenesis is not associated with any other

may even subluxate.

major ocular anomalies. Clinically, trabeculodys-

genesis is characterized by absence of the angle

7. Optic disc may show variable cupping and atrophy

recess with iris having a flat or concave direct

especially after third year.

insertion into the surface of trabeculum as follows:

8. IOP is raised which is neither marked nor acute.

Flat iris insertion is more common than the

9. Axial myopia may occur because of increase in

concave iris insertion. In it the iris inserts flatly

axial length which may give rise to anisometropic

and abruptly into the thickened trabeculum either

amblyopia.

at or anterior to scleral spur

(more often) or

posterior to scleral spur. It is often possible to

Examination (Evaluation)

visualize a portion of ciliary body and scleral

A complete examination under general anaesthesia

spur.

should be performed on each child suspected of

Concave iris insertion is less common. In it the

having congenital glaucoma. The examination should

superficial iris tissue sweeps over the

include following:

iridotrabecular junction and the trabeculum and

thus obscures the scleral spur and ciliary body.

Clinical features

1. Photophobia, blepharospasm, lacrimation and

eye rubbing often occur together. These are thought

to be caused by irritation of corneal nerves, which

occurs as a result of the elevated IOP. Photophobia is

usually the initial sign, but is not enough by itself to

arouse suspicion in most cases.

2. Corneal signs. Corneal signs include its oedema,

enlargement and Descemet’s breaks.

Fig. 9.5. A child with congenital glaucoma.

GLAUCOMA

213

1. Measurement of IOP with Schiotz or preferably

hand held Perkin’s applanation tonometer since

scleral rigidity is very low in children.

2. Measurement of corneal diameter by callipers.

3. Ophthalmoscopy to evalute optic disc.

4. Gonioscopic examination of angle of anterior

chamber reveals trabeculodysgenesis with either

flat or concave iris insertion as described in

pathogenesis.

Differential diagnosis

It is to be considered for different presenting signs

as follows:

1. Cloudy cornea. In unilateral cases the commonest

cause is trauma with rupture of Descemet’s

membrane (forceps injury). In bilateral cases

causes may be trauma, mucopolysaccharidosis,

interstitial keratitis and corneal endothelial

dystrophy.

2. Large cornea due to buphthalmos should be

differentiated from megalocornea.

3. Lacrimation in an infant is usually considered to

be due to congenital nasolacrimal duct blockage

and thus early diagnosis of congenital glaucoma

may be missed.

Fig. 9.6. Technique of goniotomy : A, showing position of

4. Photophobia may be due to keratitis or uveitis.

goniotomy knife in the angle under direct visualization; B,

5. Raised IOP in infants may also be associated

showing procedure of sweeping the knife in the angle.

with retinoblastoma, retinopathy of prematurity,

persistent primary hyperplastic vitreous, traumatic

is then withdrawn. Although the procedure may have

glaucoma and secondary congenital glaucoma

to be repeated, the eventual success rate is about 85

seen in rubella, aniridia and Sturge-Weber

percent.

syndrome.

2. Trabeculotomy. This is useful when corneal

clouding prevents visualization of the angle or in cases

Treatment

where goniotomy has failed. In this, canal of Schlemm

Treatment of congenital glaucoma is primarily

is exposed at about 12 O’clock position by a vertical

surgical. However, IOP must be lowered by use of

hyperosmotic agents, acetazolamide and beta-

scleral incision after making a conjunctival flap and

blockers till surgery is taken up. Miotics are of no

partial thickness scleral flap. The lower prong of

use in such cases.

Harm’s trabeculotome is passed along the Schlemm’s

canal on one side and the upper prong is used as a

Surgical procedures for congenital glaucoma

guide (Fig. 9.7). Then the trabeculotome is rotated so

1. Goniotomy (Fig. 9.6). In this procedure a Barkan's

as to break the inner wall over one quarter of the

goniotomy knife is passed through the limbus on the

canal. This is then repeated on the other side. The

temporal side. Under gonioscopic control the knife is

main difficulty in this operation is localization of the

passed across the anterior chamber to the nasal part

Schlemm's canal.

of the angle. An incision is made in the angle

approximately midway between root of the iris and

3. Combined trabeculotomy and trabeculectomy is

Schwalbe's ring through approximately 75°. The knife

now-a-days the preferred surgery with better results.

214

Comprehensive OPHTHALMOLOGY

PRIMARY OPEN ANGLE

GLAUCOMA AND RELATED

CONDITIONS

PRIMARY OPEN ANGLE GLAUCOMA

As the name implies, it is a type of primary glaucoma,

where there is no obvious systemic or ocular cause

of rise in the intraocular pressure. It occurs in eyes

with open angle of the anterior chamber. Primary open

angle glaucoma (POAG) also known as chronic simple

glaucoma of adult onset and is typically characterised

by slowly progressive raised intraocular pressure

(>21 mmHg recorded on at least a few occasions)

associated with characteristic optic disc cupping and

specific visual field defects.

ETIOPATHOGENESIS

Etiopathogenesis of POAG is not known exactly.

Fig. 9.7. Technique of trabeculotomy.

Some of the known facts are as follows:

(A) Predisposing and risk factors. These include

DEVELOPMENTAL GLAUCOMAS WITH

the following:

ASSOCIATED ANOMALIES

1. Heredity. POAG has a polygenic inheritance. The

A wide variety of systemic and/or ocular anomalies

approximate risk of getting disease is 10% in the

have an associated raised IOP, usually due to

siblings, and 4% in the offspring of patients with

developmental defects of the anterior chamber angle.

POAG.

2. Age. The risk increases with increasing age. The

Some of the associations are as follows:

POAG is more commonly seen in elderly between

1. Glaucoma associated with iridocorneal

5th and 7th decades.

dysgenesis. These include: posterior embryotoxon

3. Race. POAG is significantly more common,

characterised by a prominent Schwalbe’s ring

develops earlier and is more severe in black

(Axenfeld anomaly), Rieger anomaly, Rieger

people than in white.

syndrome, Peter’s anomaly and combined Rieger

4. Myopes are more predisposed than the normals.

syndrome and Peter’s anomaly.

5. Diabetics have a higher prevalence of POAG

than non-diabetics.

2. Glaucoma associated with aniridia (50% cases).

6. Cigarette smoking is also thought to increase its

3. Glaucoma associated with ectopia lentis

risk.

syndromes, which include Marfan’s syndrome,

7. High blood pressure is not the cause of rise in

Weil-Marchesani syndrome and homocystinuria.

IOP, however the prevalence of POAG is more in

hypertensives than the normotensives.

4. Glaucoma associated with phakomatosis is seen

8. Thyrotoxicosis is also not the cause of rise in

in Sturge-Weber syndrome ( 50% cases) and Von

IOP, but the prevalence of POAG is more in

Recklinghausen’s neurofibromatosis (25% cases).

patients suffering from Graves’ ophthalmic disease

5. Miscellaneous conditions. Lowe’s syndrome

than the normals.

(oculo-cerebro-renal syndrome), naevus of Ota,

(B) Pathogenesis of rise in IOP. It is certain that rise

nanophthalmos, congenital ectropion uveae,

in IOP occurs due to decrease in the aqueous outflow

congenital microcornea and rubella syndrome.

facility due to increased resistance to aqueous

GLAUCOMA

215

outflow caused by age-related thickening and

over 5 mm Hg (Schiotz) is suspicious and over 8 mm

sclerosis of the trabeculae and an absence of giant

of Hg is diagnostic of glaucoma. In later stages, IOP

vacuoles in the cells lining the canal of Schlemm.

is permanently raised above 21 mm of Hg and ranges

However, the cause of these changes is uncertain.

between 30 and 45 mm of Hg.

POAG and their offspring and sibilings are more likely

to respond to six weeks topical steroid therapy with a

significant rise of IOP.

INCIDENCE OF POAG

It varies in different populations. In general, it affects

about 1 in 100 of the general population (of either

sex) above the age of 40 years. It forms about one-

third cases of all glaucomas.

CLINICAL FEATURES

Symptoms

1. The disease is insidious and usually

asymptomatic, until it has caused a significant

loss of visual field. Therefore, periodic eye

examination is required after middle age.

2. Patients may experience mild headache and

eyeache.

3. Occasionally, an observant patient may notice a

defect in the visual field.

4. Reading and close work often present increasing

difficulties owing to accommodative failure due

to constant pressure on the ciliary muscle and its

nerve supply. Therefore, patients usually complain

of frequent changes in presbyopic glasses.

5. Patients develop delayed dark adaptation, a

disability which becomes increasingly disturbing

in the later stages.

Signs

I. Anterior segment signs. Ocular examination

including slit-lamp biomicroscopy may reveal normal

anterior segment. In late stages pupil reflex becomes

sluggish and cornea may show slight haze.

II. Intraocular pressure changes. In the initial stages

the IOP may not be raised permanently, but there is

an exaggeration of the normal diurnal variation.

Therefore, repeated observations of IOP (every 3-4

hour), for 24 hours is required during this stage

(Diurnal variation test). In most patients IOP falls

Fig. 9.8. Patterns of diurnal variations of IOP: A, normal

during the evening, contrary to what happens in

slight morning rise; B, morning rise seen in 20% cases of

closed angle glaucoma. Patterns of diurnal variation

POAG; C, afternoon rise seen in 25% cases of POAG;

of IOP are shown in Fig. 9.8. A variation in IOP of

D, biphasic variation seen in 55% cases of POAG.

216

Comprehensive OPHTHALMOLOGY

III. Optic disc changes. Optic disc changes, usually

2. Thinning of neuroretinal rim which occurs in

observed on routine fundus examination, provide an

advanced cases is seen as a crescentric shadow

important clue for suspecting POAG. These are

adjacent to the disc margin.

typically progressive, asymmetric and present a

3. Nasal shifting of retinal vessels which have the

variety of characteristic clinical patterns. It is essential,

appearance of being broken off at the margin is

therefore, to record the appearance of the nerve head

an important sign (Bayonetting sign). When the

in such a way that will accurately reveal subtle

edges overhang, the course of the vessels as

glaucomatous changes over the course of follow-up

they climb the sides of the cup is hidden.

evaluation.

4. Pulsations of the retinal arterioles may be seen

Examination techniques. Careful assessment of disc

at the disc margin

(a pathognomic sign of

changes can be made by direct ophthalmoscopy, slit-

glaucoma), when IOP is very high.

lamp biomicroscopy using a + 90D lens, Hruby lens

5. Lamellar dot sign the pores in the lamina cribrosa

or Goldmann contact lens and indirect

are slit-shaped and are visible up to the margin

ophthalmoscopy.

of the disc.

The recording and documentation techniques

include serial drawings, photography and

progresses, all the neural tissue of the disc is

photogrammetry. Confocal scanning laser topography

destroyed and the optic nerve head appears white

(CSLT) i.e., Heidelberg retinal tomograph (HRT) is an

and deeply excavated (Figs. 9.10 C&D).

accurate and sensitive method for this purpose. Other

Pathophysiology of disc changes. Both mechanical

advanced imaging techniques include optical

and vascular factors play a role in the cupping of the

coherence tomography (OCT) and scanning laser

disc.

polarimetry i.e., Nerve fibre analyser (NFA).

Mechanical effect of raised IOP forces the lamina

Glaucomatous changes in the optic disc can be

cribrosa backwards and squeezes the nerve fibres

described as early changes, advanced changes and

within its meshes to disturb axoplasmic flow.

glaucomatous optic atrophy. Figures 9.9A & B show

Vascular factors contribute in ischaemic atrophy

normal disc configuration.

of the nerve fibres without corresponding increase

(a) Early glaucomatous changes (Figs. 9.9C&D)

of supporting glial tissue. As a result, large

should be suspected to exist if fundus examination

caverns or lacunae are formed (cavernous optic

reveals one or more of the following signs:

atrophy).

1. Vertically oval cup due to selective loss of

IV. Visual field defects. Visual field defects usually

neural rim tissue in the inferior and superior

run parallel to the changes at the optic nerve head

poles.

and continue to progress if IOP is not controlled.

2. Asymmetry of the cups. A difference of more than

These can be described as early and late field defects.

0.2 between two eyes is significant.

Anatomical basis of field defects. For better

3. Large cup i.e., 0.6 or more (normal cup size is 0.3

understanding of the actual field defects, it is

to 0.4) may occur due to concentric expansion.

mandatory to have a knowledge of their anatomical

4. Splinter haemorrhages present on or near the

basis.

optic disc margin.

(A) Distribution of retinal nerve fibres (Fig. 9.11).

5. Pallor areas on the disc.

1. Fibres from nasal half of the retina come directly

6. Atrophy of retinal nerve fibre layer which may

to the optic disc as superior and inferior radiating

be seen with red free light.

fibres (srf and irf).

(b) Advanced glaucomatous changes in the optic

2. Those from the macular area come horizontally as

disc (Figs. 9.10A&B):

papillomacular bundle (pmb).

1. Marked cupping (cup size 0.7 to 0.9), excavation

3. Fibres from the temporal retina arch above and

may even reach the disc margin, the sides are

below the macula and papillomacular bundle as

steep and not shelving (c.f. deep physiological

superior and inferior arcuate fibres with a

cup).

horizontal raphe in between (saf and iaf).

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Comprehensive OPHTHALMOLOGY

Fig. 9.10. Optic disc showing advanced glaucomatous changes (A, diagramatic depiction; B, fundus photograph) and

glaucomotous optic atrophy (C, diagramatic depiction; D, fundus photograph).

Progression of field defects. Visual field defects in

glaucoma. However, it is of limited diagnostic

glaucoma are initially observed in Bjerrum’s area (10-

value, as it may also occur in many other

25 degree from fixation) and correlate with optic disc

conditions.

changes. The natural history of the progressive

2. Baring of blind spot. It is also considered to be an

glaucomatous field loss, more or less, takes the

early glaucomatous change, but is very non-specific

following sequence:

and thus of limited diagnostic value. Baring of the

1. Isopter contraction. It refers to mild generalised

blind spot means exclusion of the blind spot from

constriction of central as well as peripheral field.

the central field due to inward curve of the outer

It is the earliest visual field defect occurring in

boundary of 30° central field (Fig. 9.13A).

GLAUCOMA

219

Fig. 9.11. Distribution of retinal nerve fibres.

Fig. 9.12. Arrangement of nerve fibres within

optic nerve head.

3. Small wing-shaped paracentral scotoma

(Fig.

9.13B). It is the earliest clinically significant field

defect. It may appear either below or above the

blind spot in Bjerrum's area

(an arcuate area

extending above and below the blind spot to

between 10^oand 20^o of fixation point).

4. Seidel’s scotoma.With the passage of time

paracental scotoma joins the blind spot to form

a sickle shaped scotoma known as Seidel’s

scotoma (Fig. 9.13C).

5. Arcuate or Bjerrum’s scotoma. It is formed at a

later stage by the extension of Seidel’s scotoma

in an area either above or below the fixation point

to reach the horizontal line (Fig. 9.13D). Damage

to the adjacent fibres causes a peripheral

breakthrough.

6. Ring or double arcuate scotoma. It develops

when the two arcuate scotomas join together

(Fig. 9.13E).

7. Roenne's central nasal step. It is created when

Fig. 9.13. Field defects in POAG: A, baring of blind spot; B,

the two arcuate scotomas run in different arcs

superior paracentral scotoma; C, Seidel's scotoma; D,

and meet to form a sharp right-angled defect at

Bjerru-m's scotoma; E, double arcuate scotoma and

the horizontal meridian (Fig. 9.13E).

Roenne's central nasal step.

220

Comprehensive OPHTHALMOLOGY

8. Peripheral field defects. These appear sometimes

Note. For proper understanding of Table 9.2,

at an early stage and sometimes only late in the

evaluation of the Humphrey single field printout

disease. The peripheral nasal step of Roenne's

described on page 485 should be revised.

results from unequal contraction of the peripheral

Ocular associations

isopter.

POAG may sometimes be associated with high myopia,

9. Advanced glaucomatous field defects. The visual

Fuchs’ endothelial dystrophy, retinitis pigmentosa,

field loss gradually spreads centrally as well as

central retinal vein occlusion and primary retinal

peripherally, and eventually only a small island of

detachment.

central vision

(tubular vision) and an

accompanying temporal island are left. With the

INVESTIGATIONS

continued damage, these islands of vision also

1. Tonometry. Applanation tonometry should be

progressively diminish in size until the tiny central

preferred over Schiotz tonometry (see page 479).

island is totally extinguished. The temporal island

2. Diurnal variation test is especially useful in

of the vision is more resistant and is lost in the

end leaving the patient with no light perception.

detection of early cases (see page 215).

Diagnosis of glaucoma field defects on HFA single

3. Gonioscopy. It reveals a wide open angle of

field printout. Glaucomatous field defects should

anterior chamber. Its primary importance in POAG

always be interpreted in conjunction with clinical

is to rule out other forms of glaucoma. For details

features (IOP and optic disc changes). Further, before

(see page 206 and 546).

final interpretation, the fields must be tested twice,

4. Documentation of optic disc changes is of utmost

as there is often a significant improvement in the field

importance (see page 216).

when plotted second time (because patients become

5. Slit-lamp examination of anterior segment to

more familiar with the machine and test process).

rule out causes of secondary open angle

Criteria to grade glaucomatous field defects. The

glaucoma.

criteria to label early, moderate and severe

6. Perimetry to detect the visual field defects.

glaucomatous field defect from the HFA central 30-2

7. Nerve fibre layer analyzer (NFLA) is a recently

test, single printout is depicted in Table 9.2.

introduced device which helps in detecting the

Table 9.2: Criteria to diagnose early, moderate and severe glaucomatous field defects from HFA: 30-2- test.

Sr.

Parameter

Criteria for glaucomatous field defects

no.

Early defects

Moderate defects

Severe defects

Mean deviation (MD)

<- 6 dB

- 6dB - 12 dB

> - 12dB

Corrected pattern

Depressed to the p<5% Depressed to the p <5%

Depressed to the p<5%

standard deviation

(CPSD)

Pattern deviation plot

Points depressed

< 18 (25%)

< 37 (50%)

> 37 (>50%)

below the p < 5%

Points depressed

< 10

< 20

> 20

below the p < 1%

Glaucoma Hemifield

Outside normal limits

Test (GHT)

Sensitivity in central

No point < 15dB

One hemifield may have

Both hemifield have

5 degree

point with sensitivity

points with sensitivity

<15dB

No point has 0 dB

Any point has 0 dB

GLAUCOMA

221

glaucomatous damage to the retinal nerve fibres

before the appearance of actual visual field

changes and/or optic disc changes.

8. Provocative tests are required in border-line cases.

The test commonly performed is water drinking

test. Other provocative tests not frequently

performed include combined water drinking and

tonography, bulbar pressure test, prescoline test

and caffeine test.

Water drinking test. It is based on the theory that

glaucomatous eyes have a greater response to water

drinking. In it after an 8 hours fast, baseline IOP is

noted and the patient is asked to drink one litre of

water, following which IOP is noted every 15 min. for

1 hour. The maximum rise in IOP occurs in 15-30 min.

and returns to baseline level after 60 minutes in both

normal and the glaucomatous eyes. A rise of 8 mm of

Hg or more is said to be diagnostic of POAG.

Fig. 9.14. Triad of abnormalities in disc, field and

intraocular pressure (IOP) for the diagnosis of glaucoma.

DIAGNOSIS

not occur. The management thus requires careful and

Depending upon the level of intraocular pressure

regular periodic supervision by an ophthalmologist.

(IOP), glaucomatous cupping of the optic disc and

Therefore, it is important to perform a good baseline

the visual field changes (Fig. 9.14) the patients are

examination with which future progress can be

assigned to one of the following diagnostic entities:

compared. The initial data should include: visual

1. Primary open angle glaucoma (POAG).

Characterstically POAG is labelled when raised IOP

acuity, slit-lamp examination of anterior segment,

(>21 mm of Hg) is associated with definite

tonometry (preferably with applanation tonometer);

glaucomatous optic disc cupping and visual field

optic disc evaluation (preferably with fundus

changes.

photography), gonioscopy and visual field charting.

However, patients with raised IOP and either typical

American Academy of Ophthalmology (AAO)

field defects or disc changes are also labelled as

having POAG.

grades severity of glaucoma damage into mild,

2. Ocular hypertension or glaucoma suspect. Either

moderate and severe (Table 9.3).

of these terms is used when a patient has an IOP

constantly more than 21 mm of Hg but no optic disc

Table 9.3: Severity of glaucoma damage

or visual field changes (for details see page 224).

3. Normal tension glaucoma (NTG) or low tension

Degree

Description

glaucoma (LTG) is diagnosed when typical

glaucomatous disc cupping with or without visual

Mild

Characteristic optic-nerve abnormalities

field changes is associated with an intraocular

are consistent with glaucoma but with

pressure constantly below 21 mm of Hg (For details

normal visual field.

see page 224).

Moderate Visual-field abnormalities in one hemi-field

and not within 5 degrees of fixation.

MANAGEMENT

General considerations

Severe

Visual-field abnormalities in both

Baseline evaluation and grading of severity of

hemifields and within 5 degrees of fixation.

glaucoma. The aim of treatment is to lower intraocular

pressure to a level where (further) visual loss does

Source : AAO 2000a

222

Comprehensive OPHTHALMOLOGY

Therapeutic choices include:

IOP by reducing the aqueous secretion due to their

Medical therapy,

effect on beta - receptors in the ciliary processes.

Argon or diode laser trabeculoplasty, and

Preparations. In terms of effectiveness, there is little

Filteration surgery.

difference between various beta-blockers. However,

each offers a slight advantage over the other, which

A. Medical therapy

may help in choosing the particular medication as

The initial therapy of POAG is still medical, with

follows:

surgery as the last resort.

Timolol maleate (0.25, 0.5% : 1-2 times/day) is

Antiglaucoma drugs available are described in detail

most popular as initial therapy. However, it should

on pages 423-427.

not be used in patients having associated

bronchial asthma and/or heart blocks.

Basic principles of medical therapy of POAG

Betaxolol (0.25% : 2 times/day). Being a selective

Identification of target pressure. From the baseline

beta-1 blocker it is preferred as initial therapy in

evaluation data a ‘target pressure’ (below which

patients with cardiopulmonary problems.

glaucomatous damage is not likely to progress)

Levobunolol (0.25, 0.5% : 1-2 times/day). Its action

should be identified for each patient. The target

lasts the longest and so is more reliable for once

pressure is identified taking into account the

a day use than timolol.

severity of existing damage, the level of IOP, age,

Carteolol

(1%:

1-2 times/day). It raises

and general health of the patient. Although it is

triglycerides and lowers high density lipoproteins

not possible to predict the safe level of IOP,

the least. Therefore, it is the best choice in

however, progression is uncommon if IOP is

patients with POAG having associated

maintained at less than 16 to 18 mm of Hg in

hyperlipidemias or atherosclerotic cardiovascular

patients having mild to maderate damage. Lower

disease.

target pressures (12-14 mmHg) are required in

2. Pilocarpine (1, 2, 4%: 3-4 times/day). It is a very

patients with severe damage.

effective drug and had remained as the sheet anchor

Single drug therapy. One topically instilled

in the medical management of POAG for a long time.

antiglaucoma drug should be chosen after due

However, presently it is not being preferred as the

consideration to the patient’s personal and

first drug of choice or even as second choice. It is

medical factors. If the initial drug chosen is

because of the fact that in younger patients it causes

ineffective or intolerable, it should be replaced by

problems due to spasm of accommodation and miosis.

the drug of second choice.

Most, but not all, older patients tolerate pilocarpine

Combination therapy. If one drug is not sufficient

very well; however, axial lenticular opacities when

to control IOP then a combination therapy with

present precludes its use in many such patients.

two or more drugs should be tried.

Therefore, presently pilocarpine is being considered

Monitoring of therapy by disc changes and field

only as an adjunctive therapy where other

changes and tonometry is most essential on

combinations fail and as second choice in poor

regular follow-up. In the event of progress of

patients.

glaucomatous damage the target pressure is reset

Mechanism of action. Pilocarpine contracts

at a lower level.

longitudinal muscle of ciliary body and opens spaces

Treatment regimes. There are no clear-cut

in trabecular meshwork, thereby mechanically

prescribed treatment regimens for medical therapy of

increasing aqueous outflow.

POAG. However, at present considerations are as

3. Latanoprost (0.005%: once daily). It is a

follows :

prostaglandin by nature and decreases the IOP by

I. Single drug therapy

increasing the uveo-scleral outflow of aqueous.

1. Topical beta-blockers are being recommended as

Presently, it is being considered the drug of first choice

the first drug of choice for medical therapy of POAG

for the treatment of POAG (provided patient can

in poors and average income patients. These lower

afford to buy it). Therefore, it is a very good

GLAUCOMA

223

adjunctive drug to beta-blockers, dorzolamide and

Technique and role of ALT in POAG. It has an

even pilocarpine when additional therapy is indicated.

additive effect to medical therapy. Its hypotensive

4. Dorzolamide (2%: 2-3 times/day). It is a recently

effect is caused by increasing outflow facility,

introduced topical carbonic anhydrase inhibitor which

possibly by producing collagen shrinkage on the

lowers IOP by decreasing aqueous secretion. It has

inner aspect of the trabecular meshwork and opening

replaced pilocarpine as the second line of drug and

the intratrabecular spaces. It has been shown to lower

even as an adjunct drug.

IOP by 8-10 mm of Hg in patients on medical therapy

5. Adrenergic drugs. Role in POAG is as follows:

and by 12-16 mm in patients who are not receiving

i. Epinephrine hydrochloride (0.5, 1, 2%: 1-2 times/

medical treatment.

day) and dipivefrine hydrochloride

(0.1%: 1-2

The treatment regime usually employed consists

times/day). These drugs lower the IOP by

of 50 spots on the anterior half of the trabecular

increasing aqueous outflow by stimulating beta

recepters in the aqueous outflow system. These

meshwork over 180°.

are characterized by a high allergic reaction rate.

Complications. These include transient acute rise of

Their long-term use has also been recognized as

IOP, which can be prevented by pretreatment with

a risk factor for failure of filtration glaucoma

pilocarpine and/or acetazolamide; and inflammation

surgery. For these reasons, epinephrine

compounds are no longer being used as first line

which can be lessened by use of topical steroids for

or second line drug. However, dipivefrine may be

3-4 days. Less commonly haemorrhage, uveitis,

combined with beta-blockers in patients where

peripheral anterior synechiae and reduced

other drugs are contraindi-cated.

accommodation may occur.

ii. Brimonidine (0.2% : 2 times/day). It is a selective

alpha-2-adrenergic agonist and lowers IOP by

C. Surgical therapy

decreasing aqueous production. Because of

Indications

increased allergic reactions and tachyphylaxis

1. Uncontrolled glaucoma despite maximal medical

rates it is not considered the drug of first choice

therapy and laser trabeculoplasty.

in POAG. It is used as second drug of choice and

also for combination therapy with other drugs.

2. Non-compliance of medical therapy and non-

availability of ALT.

II. Combination topical therapy

3. Failure with medical therapy and unsuitable for

If one drug is not effective, then a combination of

two drugs—one drug which decreases aqueous

ALT either due to lack of cooperation or inability

production (timolol or other betablocker, or

to visualize the trabeculum.

brimonidine or dorzolamide) and other drug which

4. Eyes with advanced disease i.e., having very

increase aqueous outflow (latanoprost or brimonidine

high IOP, advanced cupping and advanced field

or pilocarpine) may be used.

loss should be treated with filtration surgery as

III. Role of oral carbonic anhydrase inhibitors in

primary line of management.

POAG

5. Recently, some workers are even recommending

Acetazolamide and methazolamide are not

surgery as primary line of treatment in all cases.

recommended for long-term use because of their side-

effects. However, these may be added to control IOP

Types of surgery

for short term.

Surgical treatment of POAG primarily consists of a

fistulizing (filtration) surgery which provides a new

B. Argon or diode laser trabeculoplasty (ALT or

channel for aqueous outflow and successfully

DLT)

controls the IOP

(below

21 mm of Hg).

It should be considered in patients where IOP is

Trabeculectomy is the most frequently performed

uncontrolled despite maximal tolerated medical

filtration surgery now-a-days. The details of filtration

therapy. It can also be considered as primary therapy

where there is non-compliance to medical therapy.

operations are described on page 237.

224

Comprehensive OPHTHALMOLOGY

OCULAR HYPERTENSION

Etiopathogenesis

Ocular hypertension or glaucoma suspect, either of

It is believed to result from chronic low vascular

these terms is used when a patient has an IOP

perfusion, which makes the optic nerve head

constantly more than 21 mm of Hg but no optic disc

susceptible to normal IOP. This view is supported by

or visual field changes. These patients should be

following association which are more common in NTG

carefully monitored by an ophthalmologist and

than in POAG :

should be treated as cases of POAG in the presence

Raynauld phenomenon i.e., peripheral vascular

of high risk factors

spasm on cooling,

High risk factors include:

Migraine,

Significant diurnal variation, i.e., a difference of

Nocturnal systemic hypotension and overtreated

more than 8 mm of Hg between the lowest and

systemic hypertension.

the highest values of IOP.

Reduced blood flow velocity in the ophthalmic

Significantly positive water drinking provocative

artery

(as revealed on transcranial Doppler

test.

ultrasonography).

When associated with splinter haemorrhages over

Clinical features

or near the optic disc.

IOP constantly more than 28 mm of Hg.

As described in definition the clinical features of NTG

Retinal nerve fibre large defects.

(disc changes and visual field defects) are similar to

Parapapillary changes.

POAG, but the IOP is consistantaly below 21mm Hg.

Other characterstic features of NTG are some

Central corneal thickness < 555 µm.

associations mentioned in the etiopathogenesis.

Other risk factors include:

Significant asymmetry in the cup size of the two

Differential diagnosis

eyes, i.e., a difference of more than 0.2.

1. POAG. In early stages POAG may present with

Strong family history of glaucoma.

normal IOP because of a wide diurnal variation.

When associated with high myopia, diabetes or

Diurnal variation test usually depicts IOP higher than

pigmentary changes in the anterior chamber.

21 mm of Hg at some hours of the day in patients with

Treatment

POAG.

Patients with high-risk factors should be treated

2. Congentical optic disc anomalies such as large

on the lines of POAG (see page 222). The aim

optic disc pits or colobomas may be mistaken for

should be to reduce IOP by 20%.

acquired glaucomatous damage. A careful examination

Patients with no high risk factors should be

should help in differentiation.

annually followed by examination of optic disc,

Treatment

perimetry and record of IOP. Treatment is not

1. Medical treatment to lower IOP. The aim of the

required till glaucomatous damage is documented.

treatment is to lower IOP by 30% i.e., to achieve IOP

NORMAL TENSION GLAUCOMA

levels of about 12-14 mm of Hg. Some important facts

Definition and prevalence

about medical treatment of NTG are:

Betaxolol may be considered the drug of choice

The term normal tension glaucoma (NTG), also

because in addition to lowering IOP it also

referred to as low tension glaucoma is labelled when

increases optic nerve blood flow.

typical glaucomatous disc changes with or without

visual field defects are associated with an intraocular

Other beta blockers and adrenergic drugs (such

pressure (IOP) constantly below 21 mm of Hg.

as dipiverafrine) should better be avoided

(as

Characterstically the angle of anterior chamber is open

these cause nocturnal systemic hypotension and

on gonioscopy and there is no secondary cause for

are likely to affect adversely the optic nerve

glaucomatous disc changes. NTG is varient of POAG

perfusion).

which accounts for 16% of all cases of POAG and its

Drugs with neuroprotective effect like brimonidine

prevalence above the age of 40 years is 0.2%.

may be preferred.

GLAUCOMA

225

Prostaglandin analogues, e.g., latanoprost tend

Family history. The potential for PACG is

to have a greater ocular hypotensive effect in

generally believed to be inherited.

eyes with normal IOP.

Race. In caucasians, PACG accounts for about

2. Trabeculectomy may be considered when

6% of all glaucomas and presents in sixth to

progressive field loss occurs despite IOP in lower

seventh decade. It is more common in South-East

Asians, Chinese and Eskimos but uncommon in

teens.

Blacks. In Asians it presents in the 5th to 6th

3. Systemic calcium channel blockers (e.g.,

decade and accounts for 50% of primary adult

nifedipine) may be useful in patients with confirmed

glaucomas in this ethnic group.

peripheral vasospasm.

4. Monitoring of systemic blood pressure should be

(B) Precipitating factors. In an eye that is

predisposed to develop angle closure glaucoma, any

done for 24 hours. If nocturnal dip is detected, it may

of the following factors may precipitate an attack:

be necessary to avoid night dose of anti-hypertensive

Dim illumination,

medication.

Emotional stress,

Use of mydriatic drugs like atropine, cyclopento-

late, tropicamide and phenylephrine.

PRIMARY ANGLE-CLOSURE

GLAUCOMA

sequence of events resulting in rise of IOP in an

anatomically predisposed eye is as follows:

It is a type of primary glaucoma (wherein there is no

First of all due to the effect of precipitating factors

obvious systemic or ocular cause) in which rise in

there occurs mid dilatation of the pupil which

intraocular pressure occurs due to blockage of the

increases the amount of apposition between iris and

aqueous humour outflow by closure of a narrower

anteriorly placed lens with a considerable pressure

angle of the anterior chamber.

resulting in relative pupil block (Fig. 9.15A).

ETIOLOGY

Consequently the aqueous collects in the posterior

chamber and pushes the peripheral flaccid iris

(A) Predisposing risk factors. These can be divided

anteriorly (Iris bombe) (Fig. 9.15B), resulting in

into anatomical and general factors:

appositional angle closure due to iridocorneal

I. Anatomical factors. Eyes anatomically predisposed

contact (Fig. 9.15C). Eventually there occurs rise in

to develop primary angle-closure glaucoma (PACG)

IOP which is transient to begin with. But slowly the

include:

appositional angle closure is converted into synechial

Hypermetropic eyes with shallow anterior

angle closure (due to formation of peripheral anterior

chamber.

synechiae) and an attack of rise in IOP may last long.

Eyes in which iris-lens diaphragm is placed

In some cases a mechanical occlusion of the angle

anteriorly.

by the iris is sufficient to block the drainage of

Eyes with narrow angle of anterior chamber, which

aqueous. For this reason the instillation of atropine

may be due to: small eyeball, relatively large size

in an eye with a narrow angle is dangerous, since it

of the lens and smaller diameter of the cornea or

may precipitate an attack of raised IOP.

bigger size of the ciliary body.

Plateau iris configuration.

CLINICAL PRESENTATION

II. General factors include:

Age. PACG is comparatively more common in 5th

On the basis of clinical presentation, the PACG can

decade of life.

be classified into five different clinical entities.

Sex. Females are more prone to get PACG than

Previously these were considered progressive stages

males (male to female ratio is 1:4)

of PACG. However, now it has been well established

Type of personality. It is more common in nervous

that the condition does not necessarily progress from

individuals with unstable vasomotor system.

one stage to next in an orderly sequence. In clinical

Season. Peak incidence is reported in rainy season.

practice following clinical presentations are seen:

226

Comprehensive OPHTHALMOLOGY

Clinical features

Symptoms are absent in this stage.

Signs. In suspected eyes following signs may be

elicited:

Eclipse sign. Eclipse sign, which indicates

decreased axial anterior chamber depth, can be

elicited by shining a penlight across the anterior

chamber from the temporal side and noting a

shadow on the nasal side (Fig. 9.16).

Slit-lamp biomicroscopic signs include:

Decreased axial anterior chamber depth,

Convex shaped iris lens diaphragm, and

Close proximity of the iris to cornea in the

periphery.

Gonioscopic examination shows very narrow

angle (Shaffer grade I i.e., pigmented trabecular

meshwork is not visible without indentation or

manipulation in atleast three of the four

quadrants) (see page 205 Fig 9.2)

Van Herick slit-lamp grading of the angle may

be used with a fair accuracy when a gonioscope

is not available. Here, the peripheral anterior

chamber depth

(PACD) is compared to the

adjacent corneal thickness (CT) and the presumed

angle width is graded as follows (Fig. 9.17):

Fig.

9.15. Mechanism of angle closure glaucoma:

Grade 4 (Wide open angle): PACD = ³/4 to 1 CT

A, relative pupil block; B, iris bombe formation;

C, appositional angle closure.

Grade 3 (Mild narrow angle): PACD = ¼ to

½ CT

Latent primary angle-closure glaucoma (primary

Grade 2 (Moderate narrow angle): PACD =

angle-closure glaucoma suspect).

¼ CT

Subacute

(intermittent) primary angle-closure

glaucoma.

Grade 1 ( Extremely narrow angle): PACD

Acute primary angle-closure glaucoma.

< ¼ CT

Postcongestive angle-closure glaucoma,

Grade 0 (closed angle): PACD = Nil

Chronic primary angle-closure glaucoma, and

Absolute glaucoma

Latent primary angle-closure glaucoma

The term latent primary angle-closure glaucoma

(Latent PACG) is now used for the eyes which are

anatomically predisposed to angle-closure glaucoma.

Therefore, the preferred term is primary angle-closure

glaucoma suspect i.e., eyes with shallow anterior

chamber associated with an occludable angle. The

suspect of latent angle-closure glaucoma is made:

On routine slit-lamp examination in patients coming

for some other complaints, and

In fellow eye of the patients presenting with an

Fig. 9.16. Estimation of anterior chamber depth by obliq-

attack of acute angle-closure glaucoma in one eye.

ue illumination : A, normal; B, shallow.

GLAUCOMA

227

Clinical course

Eyes with latent primary angle-closure glaucoma,

without treatment, may follow any of the following

clinical courses :

Intraocular pressure may remain normal, or

Subacute or acute angle-closure glaucoma may

occur subsequently, or

Chronic angle-closure glaucoma may develop

without passing through subacute or acute stage.

Diagnosis

Diagnosis is made by:

Clinical signs described above, and positive

provocative tests

Provocative tests. Provocative tests for PACG

suspects have been designed to precipitate closure

of the angle in the ophthalmologist’s office, where it

can be treated promptly.

1. Prone-darkroom test is the most popular and

best physiological provocative test for PACG

suspects. In this test baseline IOP is recorded

and patient is made to lie prone in a darkroom for

one hour. He must remain awake so that pupils

remain dilated. After 1 hour, the IOP is again

measured. An increase in IOP of more than 8 mm

Hg is considered diagnostic of PACG.

2. Mydriatic provocative test is usually not preferred

now-a-days because this is not physiological. In

this test either a weak mydriatic

(e.g.,

0.5%

tropicamide) or simultaneously a mydriatic and

miotic (10% phenylephrine and 2% pilocarpine)

are used to produce a mid-dilated pupil. A

pressure rise of more than 8 mm Hg is considered

positive.

Inferences from provocative tests

A positive provocative test indicates that angle is

capable of spontaneous closure.

A negative provocative test in the presence of a

narrow angle of anterior chamber does not rule

out a possibility of spontaneous closure. So,

patient should be warned of possible symptoms

of an attack of PACG.

Treatment

Prophylactic laser iridotomy should be performed

Fig. 9.17. Van Herick method of slit-lamp grading of angle

in both eyes of all the patients diagnosed as latent

width: A, Grade IV; B, Grade III; C, Grade II; and D, Grade I,

angle-closure glaucoma. If untreated, the risk of acute

and E Grade 0. PACD = Peripheral anterior chamber depth;

pressure rise during the next 5 years is about 50%.

CT = Corneal Thickeners

228

Comprehensive OPHTHALMOLOGY

Subacute or intermittent primary angle-closure

Clinical course

glaucoma

Eyes with subacute primary angle-closure glaucoma

In subacute primary angle-closure glaucoma

without treatment may have variable course :

(Subacute PACG) there occurs an attack of transient

Some eyes may develop an attack of acute primary

rise of IOP (40-50 mmHg) which may last for few

angle-closure glaucoma and

minutes to 1-2 hours. Such an attack in a patient with

Others may develop chronic primary angle-closure

occludable angle is usually precipitated by :

glaucoma without passing through acute stage.

Physiological mydriasis is e.g., while reading in

Diagnosis and treatment

dim illumination, watching television or cinema in

Same as described for latent primary angle-closure

a darkened room, or during anxiety (sympathetic

glaucoma (see page 227).

overactivity); or

Differential diagnosis of coloured halos in PACG.

Physiological shallowing of anterior chamber

Coloured halos in PACG occur due to accumulation

after lying in prone position.

of fluid in the corneal epithelium and alteration in the

Clinical features

refractive condition of the corneal lamellae. Patient

Symptoms. The episode of subacute PACG is marked

typically gives history of seeing colours distributed

by experience of unilateral transient blurring of vision,

as in the spectrum of rainbow (red being outside and

coloured halos around light, headache, browache and

violet innermost) while watching on a lighted bulb or

eyeache on the affected side.

the moon.

Self-termination of the attack occurs possibly

The coloured halos in glaucoma must be

due to physiological miosis induced by bright

differentiated from those found in acute purulent

light, sleep or otherwise.

conjunctivitis and early cataractous changes. In

Recurrent attacks of such episodes are not

conjunctivits, the halos can be eliminated by irrigating

uncommon. Between the recurrent attacks the

the discharge. The halos of glaucoma and immature

eyes are free of symptoms.

cataract may be differentiated by Fincham's test in

Signs. Usually during examination the eye is white

which a stenopaeic slit is passed across the pupil.

and not congested. However, all the signs described

During this test glaucomatous halo remains intact,

in latent primary angle-closure glaucoma can be

while a halo due to cataract is broken up into

elicited in this phase also (see page 226).

segments (Fig. 9.18).

Fig. 9.18. Emsley-Fincham stenopaeic-slit test demonstrating breaking up of halos due to

immature cataract into different segments.

GLAUCOMA

229

Acute primary angle-closure glaucoma

IOP is markedly elevated, usually between 40 and

An attack of acute primary angle closure glaucoma

70 mm of Hg,

occurs due to a sudden total angle closure leading to

Optic disc is oedematous and hyperaemic,

Fellow eye shows shallow anterior chamber and

severe rise in IOP. It usually does not terminate of its

a narrow angle (latent angle closure glaucoma).

own and thus if not treated lasts for many days. This

is sight threatening emergency.

Clinical course of acute primary angle-closure

glaucoma.

Clinical features

The clinical status of the eye after an attack of acute

Symptoms

PACG with or without treatment is referred to post

congestive glaucoma (details are given below).

Pain. Typically acute attack is characterised by

sudden onset of very severe pain in the eye

Diagnosis

which radiates along the branches of 5th nerve.

Diagnosis of an attack of primary acute congestive

Nausea, vomiting and prostrations are frequently

glaucoma is usually obvious from the clinical features.

associated with pain.

However, a differential diagnosis may have to be

Rapidly progressive impairment of vision,

considered :

redness, photophobia and lacrimation develop in

1. From other causes of acute red eye. Acute

all cases.

congestive glaucoma sometimes needs

Past history. About 5 percent patients give history

differentiation from other causes of inflammed

of typical previous intermittent attacks of subacute

red eye like acute conjunctivitis and acute

angle-closure glaucoma.

iridocyclitis (see page 146-147).

Signs (Fig. 9.19)

2. From secondary acute congestive glaucomas

Lids may be oedematous,

such as phacomorphic glaucoma, acute

Conjunctiva is chemosed, and congested, (both

neovascular glaucoma and glaucomatocyclitic

conjunctival and ciliary vessels are congested),

crisis.

Cornea becomes oedematous and insensitive,

Anterior chamber is very shallow. Aqueous flare

Management

or cells may be seen in anterior chamber ,

It is essentially surgical. However, medical therapy is

Angle of anterior chamber is completely closed

instituted as an emergency and temporary measure

as seen on gonioscopy (shaffer grade 0),

before the eye is ready for operation.

Iris may be discoloured,

(A) Medical therapy

Pupil is semidilated, vertically oval and fixed. It

is non-reactive to both light and accommodation,

1. Systemic hyperosmotic agent intravenous

mannitol (1 gm/kg body weight) should be given

initially to lower IOP.

2. Acetazolamide (a carbonic anhydrase inhibitor)

500 mg intravenous injection followed by 250 mg

tablet should be given 3 times a day.

3. Analgesics and anti-emetics as required.

4. Pilocarpine eyedrops should be started after the

IOP is bit lowered by hyperosomtic agents. At

higher pressureiris sphincter is ischaemic and

unresponsive to pilocarpine. Initially 2 percent

pilocarpine should be administered every

minutes for 1-2 hours and then 6 hourly.

5. Beta blocker eyedrops like 0.5 percent timolol

Fig. 9.19. Clinical photograph of a patient with acute con-

gestive glaucoma. Note ciliary congestion, corneal oede-

maleate or 0.5 percent betaxolol should also be

ma and middilated pupil.

administered twice a day to reduce the IOP.

230

Comprehensive OPHTHALMOLOGY

6. Corticosteroid eyedrops like dexamethasone or

2. Spontaneous angle opening may very rarely occur

betamethasone should be administered 3-4 times

in some cases and the attack of acute PACG may

a day to reduce the inflammation.

subside itself without treatment.

(B) Surgical treatment

Treatment of such cases is similar to that of subacute

1. Peripheral iridotomy. It is indicated when

angle-closure glaucoma.

peripheral anterior synechiae are formed in less

3. Chronic congestive angle-closure glaucoma is

than 50 percent of the angle of anterior chamber

continuation of acute congestive angle-closure

and as prophylaxis in the other eye. Peripheral

glaucoma when not treated or when laser P.I. is

iridotomy re-establishes communication between

unsuccessful.

posterior and anterior chamber, so it bypasses

Clinical features are:

the pupillary block and thus helps in control of

The IOP remains constantly raised,

PACG. Its surgical technique is described on

The eye remains permanently congested and

page 237.

irritable, but pain is reduced due to acclamatization.

Laser iridotomy, a non-invasive procedure, is a

Lids and conjuctival oedema is reduced,

good alternative to surgical iridectomy.

Optic disc may show glaucomatous cupping.

2. Filtration surgery. It should be performed in

Other features are similar to acute congestive

cases where IOP is not controlled with the best

angle-closure glaucoma.

medical therapy following an attack of acute

Treatment is always trabeculectomy operation after

congestive glaucoma and also when peripheral

medical control of IOP with guarded visual prognosis.

anterior synechiae are formed in more than 50

4. Ciliary body shut down. It refers to temporary

percent of the angle of the anterior chamber.

cessation of aqueous humour secretion due to

Mechanism: Filtration surgery provides an

ischaemic damage to the ciliary epithelium after an

alternative to the angle for drainage of aqueous

attack of acute PACG.

from anterior chamber into subconjunctival

Clinical features in this stage are similar to acute

space.For surgical technique, see page 238.

congestive glaucoma except that the IOP is low and

3. Clear lens extraction by phacoemulsification with

pain is markedly reduced. Subsequent recovery of

intraocular lens implantation by has recent been

ciliary function may lead to chronic elevation of IOP

recommended by some workers.

with cupping and visual field defects.

Treatment includes:

Prophylactic laser iridotomy (preferably) or surgical

Topical steroid drops to reduce inflammation.

peripheral iridectomy should be performed on the

Laser iridotomy should be performed when the

fellow asymptomatic eye.

cornea becomes clear and IOP should be

monitored.

Postcongestive angle-closure glaucoma

Trabeculectomy is required when IOP rises

As mentioned above, postcongestive angle-closure

constantly.

glaucoma refers to the clinical status of the eye after

Vogt’s triad may be seen in patients with any type of

an attack of acute PACG with or without treatment. It

postcongesive glaucoma and in treated cases of acute

may be seen in following four clinical settings :

congestive glaucoma. It is characterized by:

1. Postsurgical postcongestive PACG. This refers to

Glaucomflecken (anterior subcapsular lenticular

the clinical status of the eye after laser peripheral

opacity),

iridotomy (PI) treatment for an attack of acute PACG.

Patches of iris atrophy, and

It may occur in two clinical settings :

Slightly dilated non-reacting pupil

(due to

i. With normalized IOP after successful laser PI,

sphincter atrophy).

the eye usually quitens after some time with or

Chronic primary angle-closure glaucoma

without marks of an acute attack (i.e., Vogt’s

triad, see below).

Pathogenesis

ii. With raised IOP after unsuccessful laser PI, there

Chronic primary angle-closure glaucoma (chronic

occurs a state of chronic congestive glaucoma. It

PACG) results from gradual synechial closure of the

needs to be treated by trabeculectomy operation.

angle of anterior chamber in following circumstances:

GLAUCOMA

231

1. Creeping synechial angle-closure. It always

Anterior chamber is very shallow.

starts superiorly and gradually progresses

Iris becomes atrophic.

circumferentially to involve the 360° angle over

Pupil becomes fixed and dilated and gives a

the period.

greenish hue.

2. Attacks of subacute angle-closure glaucoma may

Optic disc shows glaucomatous optic atrophy.

eventually end up in chronic angle-closure

Intraocular pressure is high; eyeball becomes

glaucoma.

stony hard.

3. Mixed mechanism, i.e., a combination of POAG

with narrow angles. It presents as chronic angle-

Management of absolute glaucoma

closure glaucoma.

1. Retrobulbar alcohol injection: It may be given

Clinical features

to relieve pain. First, 1 ml of 2 percent xylocaine

Clinical features are similar to POAG except that angle

is injected followed after about 5-10 minutes by

is narrow. These include :

1 ml of 80 percent alcohol. It destroys the ciliary

Intraocular pressure (IOP) remains constantly

ganglion.

raised.

2. Destruction of secretory ciliary epithelium to

Eyeball remains white

(no congestion) and

lower the IOP may be carried out by cyclo-

painless,

cryotherapy (see page 240) or cyclodiathermy or

Optic disc may show glaucomatous cupping,

cyclophotocoagulation.

Visual field defects similar to POAG may occur

(see page 218).

3. Enucleation of eyeball. It may be considered

Gonioscopy reveals a variable degree of angle

when pain is not relieved by conservative

closure. Permanent peripheral anterior synechiae

methods. The frequency with which a painful

do not usually develop until late. The gonioscopic

blind eye with high IOP contains a malignant

findings provide the only differentiating feature

growth, justifies its removal. For surgical technique

between POAG and chronic PACG.

of enucleation (see page 284).

Treatment

Complications. If not treated, due to prolonged high

Laser iridotomy alone or along with medical

IOP following complications may occur:

therapy should be tried first.

1. Corneal ulceration. It results from prolonged

Trabeculectomy

(filtration surgery) is needed

epithelial oedema and insensitivity. Sometimes,

when the above treatment fails to control IOP.

corneal ulcer may even perforate.

Prophylactic laser iridotomy in fellow eye must

also be performed.

2. Staphyloma formation. As a result of continued

high IOP, sclera becomes very thin and atrophic

Absolute primary angle-closure glaucoma

and ultimately bulges out either in the ciliary

The chronic phase, if untreated, with or without the

region (ciliary staphyloma) or equatorial region

occurrence of intermittent subacute attacks, gradually

(equatorial staphyloma).

passes into the final phase of absolute glaucoma.

3. Atrophic bulbi. Ultimately the ciliary body

Clinical features

degenerates, IOP falls and the eyeball shrinks.

Painful blind eye. The eye is painful, irritable and

completely blind (no light perception).

Perilimbal reddish blue zone i.e., a slight ciliary

SECONDARY GLAUCOMAS

flush around the cornea due to dilated anterior

ciliary veins.

Caput medusae i.e., a few prominent and enlarged

Secondary glaucoma per se is not a disease entity,

vessels are seen in long standing cases.

but a group of disorders in which rise of intraocular

Cornea in early cases is clear but insensitive.

pressure is associated with some primary ocular or

Slowely it becomes hazy and may develop

systemic disease. Therefore, clinical features comprise

epithelial bullae (bullous keratopathy) or filaments

that of primary disease and that due to effects of

(filamentary keratitis).

raised intraocular pressure.

232

Comprehensive OPHTHALMOLOGY

Classification

Clinical presentation. Phacomorphic glaucoma

presents as acute congestive glaucoma with features

(A) Depending upon the mechanism of rise in IOP

almost similar to acute primary angle-closure

1. Secondary open angle glaucomas in which

glaucoma (see page 229) except that the lens in always

aqueous outflow may be blocked by a

cataractous and swollen (Fig. 9.20).

pretrabecular membrane, trabecular clogging,

Treatment should be immediate and consists of :

oedema and scarring or elevated episcleral venous

pressure.

Medical treatment to control IOP by i.v. mannitol,

2. Secondary angle closure glaucomas which may

systemic acetazolamide and topical betablockers.

or may not be associated with pupil block.

Cataract extraction with implantation of PCIOL

(which is the main treatment of phacomorphic

(B) Depending upon the causative primary disease,

glaucoma) should be performed once the eye

secondary glaucomas are named as follows:

becomes quite,

Lens-induced (phacogenic) glaucomas.

Inflammatory glaucoma

(glaucoma due to

2. Phacolytic glaucoma (Lens protein glaucoma)

intraocular inflammation).

Pathogensis. It is a type of secondary open angle

Pigmentary glaucoma.

glaucoma, in which trabecular meshwork is clogged

Neovascular glaucoma.

by the lens proteins and macrophages which have

Glaucomas associated with irido-corneal

phagocytosed the lens proteins. Leakage of the lens

endothelial syndromes.

proteins occurs through an intact capsule in the

Pseudoexfoliative glaucoma.

hypermature (Morgagnian) cataractous lens.

Glaucomas associated with intraocular

Clinical features. The condition is characterised by:

haemorrhage.

Features of congestive glaucoma due to an acute

Steroid-induced glaucoma.

rise of IOP in an eye having hypermature cataract.

Traumatic glaucoma.

Anterior chamber may become deep and aqueous

10. Glaucoma-in-aphakia.

may contain fine white protein particles.

11. Glaucoma associated with intraocular tumours.

Management. It consists of medical therapy to lower

the IOP followed by extraction of the hypermature

LENS-INDUCED (PHACOGENIC) GLAUCOMAS

cataractous lens with PCIOL implantation.

In this group IOP is raised secondary to some disorder

of the crystalline lens. It includes following subtypes:

1. Phacomorphic glaucoma

Causes. Phacomorphric glaucoma is an acute

secondary angle-closure glaucoma caused by :

Intumescent lens i.e., swollen cataractous lens

due to rapid maturation of cataract or sometimes

following traumatic rupture of capsule is the main

cause of phacomorphic glaucoma.

Anterior subluxation or dislocation of the lens

and spherophakia

(congenital small spherical

lens) are other causes of phacomorphic glaucoma.

Pathogenesis. The swollen lens pushes the iris

forward and oblitrates the angle resulting in

secondary acute angle closure-glaucoma. Further,

the increased iridocorneal contact also causes

Fig. 9.20. Phacomorphic glaucoma. Note ciliary congesti-

on, dilated pupil and intumescent senile cataractous lens.

potential pupillary block and iris bombe formation.

GLAUCOMA

233

It includes:

3. Lens particle glaucoma

i. Non-specific hypertensive uveitis, and

Pathogenesis. It is a type of secondary open angle

ii. Specific hypertensive uveitis syndromes

glaucoma, in which trabecular meshwork is blocked

i. Non-specific hypertensive uveitis. It includes all

by the lens particles floating in the aqueous humour.

cases of acute inflammation of the anterior uveal tract

It may occur due to lens particles left after accidental

associated with raised IOP, other than the specific

or planned extracapsular cataract extraction or

hypertensive uveitis syndromes, but inclusive of

following traumatic rupture of the lens.

postoperative inflammation.

Clinical features. Raised IOP associated with lens

Mechanisms of rise in IOP. A secondary open-angle

particles in the anterior chamber.

glaucoma occurs due to trabecular clogging (by

Management includes medical therapy to lower IOP

inflammatory cells, exudates and turbid aqueous

and irrigation-aspiration of the lens particles from the

humour), trabecular oedema (due to associated

anterior chamber.

trabeculitis), and prostaglandin-induced rise in IOP.

Management. It includes treatment of iridocyclitis and

4. Glaucoma associated with phacogenic uveitis

medical therapy to lower IOP by use of hyperosmotic

Pathogenesis. In this condition IOP is raised due to

agents, acetazolamide and beta- blocker eyedrops

inflammatory reaction of the uveal tissue excited by

(timolol or betaxolol).

the lens matter. Basically, it is also a type of secondary

ii. Specific hypertensive uveitis syndromes. These

open angle glaucoma where trabecular meshwork is

include:

clogged by both inflammatory cells and the lens

Fuchs’ uveitis syndrome (see page 160) and

particles.

Glaucomatocyclitic crisis (see page 160).

Management consists of medical therapy to lower

2. Post-inflammatory glaucoma

IOP, treatment of iridocyclitis with steroids and

In it IOP is raised due to after-effects of the

cycloplegics. Irrigation-aspiration of the lens matter

iridocyclitis.

from anterior chamber (if required) should always be

done after proper control of inflammation.

Mechanisms of rise in IOP. include :

Pupillary block due to annular synechiae or

5. Glaucoma associated with phacoanaphylaxis

occlusio pupillae,

In this condition, there occurs fulminating acute

Secondary angle-closure with pupil block

inflammatory reaction due to antigen (lens protein) -

following iris bombe formation,

antibody reaction. The mechanism of rise in IOP and

Secondary angle-closure without pupil block

its management is similar to that of phacogenic

due to organisation of the inflammatory debris in

uveitis.

the angle.

Secondary open-angle glaucoma due to

GLAUCOMAS DUE TO UVEITIS

trabecular scarring and obstruction of the

The IOP can be raised by varied mechanisms in

meshwork.

inflammations of the uveal tissue (iridocyclitis). Even

in other ocular inflammations such as keratitis and

Management. It includes prophylaxis and curative

scleritis, the rise in IOP is usually due to secondary

treatment.

involvement of the anterior uveal tract.

1. Prophylaxis. Acute iridocylitis should be treated

energetically with local steroids and atropine to

Types. Glaucomas associated with uveitis can be

prevent formation of synechiae.

divided into two main groups:

2. Curative treatment. It consists of medical therapy

1. Hypertensive uveitis.

to lower IOP (miotics are contraindicated). Surgical

2. Post-inflammatory glaucoma.

or laser iridotomy may be useful in pupil block

1. Hypertensive uveitis

without angle closure. Filtration surgery may be

Hypertensive uveitis refers to acute inflammation of

performed (with guarded results) in the presence

the anterior uvea associated with raised IOP.

of angle closure.

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Comprehensive OPHTHALMOLOGY

PIGMENTARY GLAUCOMA

3. Secondary angle closure glaucoma— due to

It is a type of secondary open-angle glaucoma

goniosynechiae resulting from contracture of the

wherein clogging up of the trabecular meshwork

neovascular membrane (zipper-angle closure).

occurs by the pigment particles. About 50% of

Treatment of NVG is usually frustrating.

patients with the pigment dispersion syndrome

Panretinal photocoagulation may be carried out

develop glaucoma .

to prevent further neovascularization.

Pathogenesis. Exact mechanism of pigment shedding

Medical therapy and conventional filtration

is not known. It is believed that, perhaps, pigment

surgery are usually not effective in controlling

release is caused by mechanical rubbing of the

the IOP.

posterior pigment layer of iris with the zonular fibrils.

Artificial filtration shunt (Seton operation) may

control the IOP.

Clinical features. The condition typically occurs in

young myopic males. Characteristic glaucomatous

GLAUCOMA ASSOCIATED WITH

features are similar to primary open angle glaucoma

INTRAOCULAR TUMOURS

(POAG), associated with deposition of pigment

Secondary glaucoma due to intraocular tumours such

granules in the anterior segment structures such as

as malignant melanoma (of iris, choroid, ciliary body)

iris, posterior surface of the cornea (Krukenberg’s

and retinoblastoma may occur by one or more of the

spindle), trabecular meshwork, ciliary zonules and

following mechanisms:

the crystalline lens. Gonioscopy shows pigment

Trabecular block due to clogging by tumour

accumulation along the Schwalbe’s line especially

cells or direct invasion by tumour seedlings.

inferiorly (Sampaolesi’s line). Iris transillumination

Neovascularization of the angle.

shows radial slit-like transillumination defects in the

Venous stasis following obstruction of the vortex

mid periphery (pathognomonic feature).

veins.

Angle closure due to forward displacement of

Treatment. It is exactly on the lines of primary open

iris-lens diaphragm by increasing tumour mass.

angle glaucoma.

Treatment. Enucleation of the eyeball should be

carried out as early as possible.

NEOVASCULAR GLAUCOMA (NVG)

It is an intractable glaucoma which results due to

PSEUDOEXFOLIATIVE GLAUCOMA

formation of neovascular membrane involving the

(GLAUCOMA CAPSULARE)

angle of anterior chamber.

Pseudoexfoliation syndrome (PES) is characterised

Etiology. It is usually associated with neovas-

by deposition of an amorphous grey dandruff-like

cularization of iris (rubeosis iridis). Neovascularization

material on the pupillary border, anterior lens surface,

develops following retinal ischaemia, which is a

posterior surface of iris, zonules and ciliary processes.

common feature of :

The exact source of the exfoliative material is still not

Diabetic retinopathy,

known. The condition is associated with secondary

Central retinal vein occlusion,

open-angle glaucoma in about 50 per cent of the

Sickle-cell retinopathy and

cases. Exact mechanism of rise of IOP is also not

Eales’ disease.

clear. Trabecular blockage by the exfoliative material

Other rare causes are chronic intraocular

is considered as the probable cause. Clinically the

glaucoma behaves like POAG and is thus managed

inflammations, intraocular tumours, long-standing

on the same lines.

retinal detachment and central retinal artery

occlusion.

GLAUCOMAS-IN-APHAKIA/PSEUDOPHAKIA

Clinical profile. NVG occurs in three stages :

It is the term used to replace the old term ‘aphakic

1. Pre-glaucomatous stage (stage of rubeosis iridis);

glaucoma’. It implies association of glaucoma with

2. Open-angle glaucoma stage— due to formation

aphakia or pseudophakia. It includes following

of a pretrabecular neovascular membrane; and

conditions:

GLAUCOMA

235

1. Raised IOP with deep anterior chamber in early

phagocytose the debris from the aqueous humour.

postoperative period: It may be due to hyphaema,

Corticosteroids are known to suppress the

phagocytic activity of endothelial cells leading to

inflammation, retained cortical matter or vitreous

collection of debris in the trabecular meshwork

filling the anterior chamber.

and decreasing the aqueous outflow.

2. Secondary angle-closure glaucoma due to flat

Prostaglandin theory. Prostaglandin E and F

anterior chamber. It may occur following long-

(PGE and PGF) are known to increase the aqueous

standing wound leak.

outflow facility. Corticosteroids can inhibit the

3. Secondary angle-closure glaucoma due to pupil

synthesis of PGE and PGF leading to decrease in

block. It may occur following formation of annular

aqueous outflow facility and increase in IOP.

synechiae or vitreous herniation.

Note: May be all the above mechanisms and/or some

4. Undiagnosed pre-existing primary open-angle

other mechanism may be responsible for steroid

glaucoma may be associated with aphakia/

induced glaucoma.

pseudophakia.

Clinical features. Steroid-induced glaucoma typically

5. Steroid-induced glaucoma. It may develop in

resembles POAG (page 215). It usually develops

patients operated for cataract due to postoperative

following weeks of topical therapy with strong

treatment with steroids.

steroids and months of therapy with weak steroids.

6. Epithelial ingrowth may cause an intractable

Management. It can be prevented by a judicious

glaucoma in late postoperative period by invading

use of steroids and a regular monitoring of IOP when

the trabeculum and the anterior segment

steroid therapy is a must. Its treatment consists of:

structures.

Discontinuation of steroids. IOP may normalise

7. Aphakic/pseudophakic malignant glaucoma (see

within 10 days to 4 weeks in 98 percent of cases.

page

236).

Medical therapy with 0.5% timolol maleate is

effective during the normalisation period.

STEROID-INDUCED GLAUCOMA

Filtration surgery is required occasionally in

It is a type of secondary open-angle glaucoma which

intractable cases.

develops following topical, and sometimes systemic

steroid therapy.

TRAUMATIC GLAUCOMA

Etiopathogenesis. It has been postulated that the

A secondary glaucoma may complicate perforating

response of IOP to steroids is genetically determined.

as well as blunt injuries.

Roughly, 5 percent of general population is high

Mechanisms. Traumatic glaucoma may develop by

steroid responder (develop marked rise of IOP after

one or more of the following mechanisms:

about 6 weeks of steroid therapy), 35 percent are

Inflammatory glaucoma due to iridocyclitis,

moderate and 60 percent are non-responders. The

precise mechanism responsible for the obstruction

Glaucoma due to intraocular haemorrhage,

to aqueous outflow is unknown. Following theories

Lens-induced glaucoma due to ruptured, swollen

have been put forward :

or dislocated lens,

Glycosaminoglycans

(GAG) theory. Corticos-

Angle-closure due to peripheral anterior synechiae

teroids inhibit the release of hydrolases

(by

formation following perforating corneal injury

stabilizing lysosomal membrane). Consequently

producing adherant leucoma.

the GAGs present in the trabecular meshwork

Epithelial or fibrous in growth, may involve

cannot depolymerize and they retain water in the

trabeculum.

extracellular space. This leads to narrowing of

Angle recession

(cleavage) glaucoma due to

trabecular spaces and decrease in aqueous

disruption of trabecular meshwork followed by

outflow.

fibrosis.

Endothelial cell theory. Under normal

Management. It consists of medical therapy with

circumstances the endothelial cells lining the

topical 0.5 percent timolol and oral acetazolamide,

trabecular meshwork act as phagocytes and

treatment of associated causative mechanism (e.g.,

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Comprehensive OPHTHALMOLOGY

atropine and steroids for control of inflammation) and

closure glaucoma). On examination the main features

surgical intervention according to the situation.

of the ciliary block glaucoma noted are

Persistent flat anterior chamber following any

CILIARY BLOCK GLAUCOMA

intraocular operation,

Ciliary block glaucoma (originally termed as

Markedly raised IOP in early postoperative

malignant glaucoma) is a rare condition which may

period,

occur as a complication of any intraocular operation.

Negative Seidel’s test and

It classically occurs in patients with primary angle

Unresponsiveness or even aggravation by

closure glaucoma operated for peripheral iridectomy

miotics.

or filtration (e.g. trabeculectomy) surgery. It is

Malignant glaucoma may be phakic, aphakic or

characterised by a markedly raised IOP associated

pseudophakic.

with shallow or absent anterior chamber.

Management. Medical therapy consists of 1 percent

Mechanism of rise in IOP. It is believed that, rarely

atropine drops or ointment to dilate ciliary ring and

following intraocular operation, the tips of ciliary

break the cilio-lenticular or cilio-vitreal contact,

processes rotate forward and press against the

acetazolamide 250 mg QID and 0.5 percent timolol

equator of the lens in phakic eyes (cilio-lenticular

maleate eyedrops to decrease aqueous production,

block) or against the intraocular lens (cilio-IOL

and intravenous mannitol to cause deturgesence of

block) or against the anterior hyaloid phase of

the vitreous gel. YAG laser hyaloidotomy can be

vitreous in aphakic eyes (cilio-vitreal block) and thus

undertaken in aphakic and pseudophakic patients. If

block the forward flow of aqueous humour, which is

the condition does not respond to medical therapy in

diverted posteriorly and collects as aqueous pockets

4-5 days, surgical therapy in the form of pars plana

in the vitreous (Fig. 9.21). As a consequence of this

vitrectomy with or without lensectomy (as the case

the iris lens diaphragm is pushed forward, IOP is

may be) is required when the above measures fail. It

raised and anterior chamber becomes flat.

is usually effective, but sometimes the condition

Clinical features. Patient develops severe pain and

tends to recur.

blurring of vision following any intraocular operation

Note : It is important to note that the fellow eye is

(usually after peripheral iridectomy, filtering surgery

also prone to meet the same fate.

or trabeculectomy in patients with primary angle-

GLAUCOMAS ASSOCIATED WITH INTRAOCULAR

HAEMORRHAGES

Intraocular haemorrhages include hyphaema and/or

vitreous haemorrhage due to multiple causes. These

may be associated with following types of glaucomas:

1. Red cell glaucoma. It is associated with fresh

traumatic hyphaema. It is caused by blockage of

trabeculae by RBCs in patients with massive

hyphaema (anterior chamber full of blood). It may be

associated with pupil block due to blood clot. Blood

staining of the cornea may develop, if the IOP is not

lowered within a few days.

2. Haemolytic glaucoma. It is an acute secondary

open angle glaucoma due to the obstruction

(clogging) of the trabecular meshwork caused by

macrophages laden with lysed RBC debris.

3. Ghost cell glaucoma. It is a type of secondary

Fig. 9.21. Pockets of aqueous humour in the vitreous

in patients with ciliary-block glaucoma.

open angle glaucoma which occurs in aphakic or

GLAUCOMA

237

pseudophakic eyes with vitreous haemorrhage. After

SURGICAL PROCEDURES FOR

about 2 weeks of haemorrhage the RBCs degenerate,

GLAUCOMA

lose their pliability and become khaki-coloured cells

(ghost cells) which pass from the vitreous into the

anterior chamber, and block the pores of trabeculae

PERIPHERAL IRIDECTOMY

leading to rise in IOP.

Indications

4. Hemosiderotic glaucoma. It is a rare variety of

1. Treatment of all stages of primary angle-closure

secondary glaucoma occurring due to sclerotic

glaucoma.

changes in trabecular meshwork caused by the iron

2. Prophylaxis in the fellow eye.

from the phagocytosed haemoglobin by the

Note. Laser iridotomy should always be perferred over

endothelial cells of trabeculum.

surgical iridectomy.

GLAUCOMAS ASSOCIATED WITH

Surgical technique (Fig. 9.22)

IRIDOCORNEAL ENDOTHELIAL SYNDROMES

1. Incision. A 4 mm limbal or preferably corneal

incision is made with the help of razor blade

Iridocorneal endothelial (ICE) syndromes include three

fragment.

clinical entities:

2. Iris prolapsed. The posterior lip of the wound is

Progressive iris atrophy,

depressed so that the iris prolapses. If the iris

Chandler’s syndrome, and

does not prolapse, it is grasped at the periphery

Cogan-Reese syndrome.

with iris forceps.

3. Iridectomy. A small full thickness piece of iris is

Pathogenesis. The common feature of the ICE

excised by de Wecker's scissors.

syndromes is the presence of abnormal corneal

4. Reposition of iris. Iris is reposited back into the

endothelial cells which proliferate to form an

anterior chamber by stroking the lips of the

endothelial membrane in the angle of anterior

wound or with iris repositors.

chamber. Glaucoma is caused by secondary synechial

5. Wound closure is done with one or two 10-0

angle-closure as a result of contraction of this

nylon sutures with buried knots.

endothelial membrane.

6. Subconjunctival injection of dexamethasone 0.25

ml and gentamicin 0.5 ml is given.

Clinical features. The ICE syndromes typically affect

7. Patching of eye is done with a sterile eye pad

middle-aged women. The raised IOP is associated

and sticking plaster.

with characteristic features of the causative condition.

‘progressive iris atrophy’, iris features

GONIOTOMY AND TRABECULOTOMY

predominate with marked corectopia, atrophy and

These operations are indicated in congenital and

hole formation.

developmental glaucomas. For details, see page

While in Chandler’s syndrome, changes in iris

213.

are mild to absent and the corneal oedema even

at normal IOP predominates.

FILTERING OPERATIONS

Hallmark of Cogan-Reese syndrome is nodular or

Filtering operations provide a new channel for

diffuse pigmented lesions of the iris (therefore

aqueous outflow and successfully control the IOP

also called as iris naevus syndrome) which may

(below 21 mm of Hg). Fistulizing operations can be

or may not be associated with corneal changes.

divided into three groups :

1. Free-filtering operations (Full thickness fistula).

Treatment is usually frustating :

These are no longer performed now-a-days,

Medical treatment is often ineffective

because of high rate of postoperative

Trabeculectomy operation usually fails,

complications. Their names are mentioned only

Artificial filteration shunt may control the IOP.

for historical interest. These operations included

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Comprehensive OPHTHALMOLOGY

2. Primary open-angle glaucoma not controlled with

medical treatment.

3. Congenital and developmental glaucomas where

trabeculotomy and goniotomy fail.

4. Secondary glaucomas where medical therapy is

not effective.

Mechnanisms of filtration

1. A new channel (fistula) is created around the

margin of scleral flap, through which aqueous

flows from anterior chamber into the

subconjunctival space.

2. If the tissue is dissected posterior to the scleral

spur, a cyclodialysis may be produced leading to

increased uveoscleral outflow.

3. When trabeculectomy was introduced, it was

thought that aqueous flows through the cut ends

of Schlemm’s canal. However, now it is established

that this mechanism has a negligible role.

Sugical technique of trabeculectomy (Fig. 9.23)

Initial steps of anaesthesia, cleansing, draping,

exposure of eyeball and fixation with superior

rectus suture are similar to cataract operation

(see page 187).

Conjunctival flap (Fig. 9.23A). A fornix-based or

limbal-based conjunctival flap is fashioned and

the underlying sclera is exposed. The Tenon’s

Fig. 9.22. Technique of peripheral iridectomy: A, anterior

capsule is cleared away using a Tooke’s knife,

limbal incision to open the anterior chamber; B, prolapse of

and haemostasis is achieved with cautery.

peripheral iris by pressure at the posterior lip of the incision;

C, excision of the prolapsed knuckle of the iris by de Weck-

Scleral flap

(Fig.

9.23B). A partial thickness

er's scissors; D, suturing the wound.

(usually half) limbal-based scleral flap of 5 mm ×

5 mm size is reflected down towards the cornea.

Elliot's sclero-corneal trephining, punch

Excision of trabecular tissue

(Fig.

9.23B): A

sclerectomy, Scheie's thermosclerostomy and

narrow strip (4 mm × 2 mm) of the exposed deeper

iridencleisis.

sclera near the cornea containing the canal of

2. Guarded filtering surgery (Partial thickness fistula

Schlemm and trabecular meshwork is excised.

e.g., trabeculectomy).

Peripheral iridectomy (Fig. 9.23C). is performed

3. Non-penetrating filtration surgery e.g., deep

at 12 O’clock position with de Wecker’s scissors.

sclerectomy and viscocanalostomy.

Closure. The scleral flap is replaced and 10-0

nylon sutures are applied. Then the conjunctival

Trabeculectomy

flap is reposited and sutured with two interrupted

Trabeculectomy, first described by Carain in 1980 is

sutures

(in case of fornix-based flap) or

the most frequently performed partial thickness

continuous suture (in case of limbal-based flap)

filtering surgery till date.

(Fig. 9.23D).

Indications

Subconjunctival injections of dexamethasone and

1. Primary angle-closure glaucoma with peripheral

gentamicin are given.

anterior synechial involving more than half of the

Patching. Eye is patched with a sterile eye pad

angle.

and sticking plaster or a bandage.

GLAUCOMA

239

4. Patients treated with topical antiglaucoma

medications (particularly sympathomimetics) for

over three years.

5. Chronic cicatrizing conjunctival inflammation.

Antimetabolite agents. Either 5-fluorouracil (5-FU)

or mitomycin-C can be used. Mitomycin-C is only

used at the time of surgery. A sponge soaked in 0.02%

(2 mg in 10 ml) solution of mitomycin-C is placed at

the site of filtration between the scleral and Tenon’s

capsule for 2 minutes, followed by a thorough

irrigation with balanced salt solution.

Sutureless trabeculectomy

Sutureless trabeculectomy can be done through a

valvular sclero-corneal tunnel incision ( 4mm × 4 mm

size) using a specially designed Kelly’s punch

(Fig. 9.24). IOP reduction is inferior to that achieved

with conventional trabeculectomy.

Non-penetrating filteration surgery

Recently some techniques of non-penetrating

filteration surgery (in which anterior chamber is not

entered) have been advocated to reduce the incidence

of post-operative endophthalmitis, overfiltration and

hypotony. Main disadvantage of non-penetrating

filteration surgery is inferior IOP control as compared

to conventional trabeculectomy. The two currently

Fig. 9.23. Technique of trabeculectomy: A, fornix-based

used procedures are:

conjunctival flap; B & C, partial thickness scleral flap and

1. Deep sclerectomy. In this procedure, after making

excision of trabecular tissue; D, peripheral iridectomy and

closure of scleral flap; E, closure of conjunctival flap.

a partial thickness scleral flap, (as in conventional

trabeculectomy, Fig.9.23A), a second deep partial-

Complications

thickness scleral flap is fashioned and excised leaving

A few common complications are postoperative

behind a thin membrane consisting of very thin sclera,

shallow anterior chamber, hyphaema, iritis, cataract

trabeculum and Descemet’s membrane (through

due to accidental injury to the lens, and

which aqueous diffuses out). The superficial scleral

endophthalmitis (not very common).

flap is loosly approximated and conjunctival incision

is closed.

Use of antimetabolites with trabeculectomy

2. Viscocanalostomy. It is similar to deep

It is recommended that antimetabolites should be used

sclerectomy, except that after excising the deeper

for wound modulation, when any of the following

scleral flap, high viscosity viscoelastic substance is

risk factors for the failure of conventional

injected into the Schlemm's canal with a special

trabeculectomy are present :

cannula.

1. Previous failed filtration surgery.

2. Glaucoma-in-aphakia.

ARTIFICIAL DRAINAGE SHUNT OPERATIONS

3. Certain secondary glaucomas e.g. inflammatory

Artificial drainage shunts or the so called glaucoma

glaucoma, post-traumatic angle recession

valve implants are plastic devices which allow

glaucoma, neovascular glaucoma and glaucomas

aqueous outflow by creating a communication

associated with ICE syndrome.

between the anterior chamber and sub-Tenon’s space.

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Comprehensive OPHTHALMOLOGY

Fig. 9.24. Sutureless trabeculectomy.

The operation using glaucoma valve implant is also

known as Seton operation.

Glaucoma valve implants commonly used include

Molteno (Fig. 9.25) Krupin-Denver and AGV.

Indications of artificial drainage shunts include :

Neovascular glaucoma;

Glaucoma with aniridia; and

Intractable cases of primary and secondary

glaucoma where even trabeculectomy with adjunct

antimetabolite therapy fails.

CYCLO-DESTRUCTIVE PROCEDURES

Cyclo-destructive procedures lower IOP by

destroying part of the secretory ciliary epithelium

thereby reducing aqueous secretion.

Indications. These procedure are used mainly in

absolute glaucomas.

Cyclo-destructive procedures in current use are:

1. Cyclocryotherapy (most frequent),

2. Nd: Yag laser cyclodestruction, and

Fig. 9.25. Artificial drainage shunt operation using Molteno

3. Diode laser cyclophotocoagulation.

implant.

Diseases of

CHA1

the Vitreous

APPLIED ANATOMY

Synchysis scintillans

VITREOUS LIQUEFACTION

Red cell opacities

VITREOUS DETACHMENT

Tumour cell opacities

VITREOUS OPACITIES

VITREOUS HAEMORRHAGE

Developmental

VITRECTOMY

Inflammatory

With liquefaction

Open sky vitrectomy

Amyloid degeneration

Pars plana vitrectomy

Asteroid hyalosis

Vitreous substitutes

The attachment of the anterior hyaloid membrane to

APPLIED ANATOMY

the posterior lens surface is firm in the young and

weak in the elderly whereas posterior hyaloid

Vitreous humour is an inert, transparent, jelly-like

membrane remains loosely attached to the internal

structure that fills the posterior four-fifth of the cavity

limiting membrane of the retina throughout life. These

of eyeball and is about 4 ml in volume. It is a

membranes cannot be discerned in a normal eye

hydrophilic gel that mainly serves the optical

unless the lens has been extracted and posterior

functions. In addition, it mechanically stabilizes the

vitreous detachment has occurred.

volume of the globe and is a pathway for nutrients to

reach the lens and retina.

2. The main vitreous body (nucleus). It has a less

dense fibrillar structure and is a true biological gel. It

Structure. The normal youthful vitreous gel is

is here where liquefactions of the vitreous gel start

composed of a network of randomly-oriented collagen

first. Microscopically the vitreous body is

fibrils interspersed with numerous spheroidal

homogenous, but exhibits wavy lines as of watered

macromolecules of hyaluronic acid. The collapse of

silk in the slit-lamp beams. Running down the centre

this structure with age or otherwise leads to

of the vitreous body from the optic disc to the

conversion of the gel into sol. The vitreous body

posterior pole of the lens is the hyaloid canal

can be divided into two parts: the cortex and the

(Cloquet’s canal) of doubtful existence in adults.

nucleus (the main vitreous body) (Fig. 10.1).

Down this canal ran the hyaloid artery of the foetus.

1. Cortical vitreous. It lies adjacent to the retina

posteriorly and lens, ciliary body and zonules

Attachments. The part of the vitreous about 4 mm

anteriorly. The density of collagen fibrils is greater in

across the ora serrata is called as vitreous base, where

this peripheral part. The condensation of these fibrils

the attachment of the vitreous is strongest. The other

form a false anatomic membrane which is called as

firm attachments are around the margins of the optic

anterior hyaloid membrane anterior to ora serrata

disc, foveal region and back of the crystalline lens by

and posterior hyaloid membrane posterior to ora.

hyloidocapsular ligament of Wieger.

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Comprehensive OPHTHALMOLOGY

Fig. 10.1. Gross anatomy of the vitreous.

VITREOUS DETACHMENTS

DISORDERS OF THE VITREOUS

1. Posterior vitreous detachment (PVD)

VITREOUS LIQUEFACTION (SYNCHYSIS)

It refers to the separation of the cortical vitreous from

the retina anywhere posterior to vitreous base (3-4

Vitreous liquefaction (synchysis) is the most common

mm wide area of attachment of vitreous to the ora

degenerative change in the vitreous.

serrata).

Causes of liquefaction include:

1. Degenerations such as senile, myopic, and that

PVD with vitreous liquefaction (synchysis) and

collapse (synersis) is of common occurrence in

associated with retinitis pigmentosa.

2. Post-inflammatory, particularly following uveitis.

majority of the normal subjects above the age of 65

years (Fig. 10.2). It occurs in eyes with senile

3. Trauma to the vitreous which may be mechanical

(blunt as well as perforating).

liquefaction, developing a hole in the posterior

4. Thermal effects on vitreous following diathermy,

hyaloid membrane. The synchytic fluid collects

photocoagulation and cryocoagulation.

between the posterior hyaloid membrane and the

5. Radiation effects may also cause liquefaction.

internal limiting membrane of the retina, and leads to

Clinical features. On slit-lamp biomicroscopy the

PVD up to the base along with collapse of the

vitreous liquefaction (synchysis) is characterised by

remaining vitreous gel (synersis). These changes

absence of normal fine fibrillar structure and visible

occur more frequently in the aphakics than the phakics

pockets of liquefaction associated with appearance

and in the myopes than the emmetropes.

of coarse aggregate material which moves freely in

Clinical features. PVD may be associated with flashes

the free vitreous. Liquefaction is usually associated

of light and floaters. Biomicroscopic examination of

with collapse (synersis) and opacities in the vitreous

the vitreous reveals a collapsed vitreous (synersis)

which may be seen subjectively as black floaters in

behind the lens and an optically clear space between

front of the eye.

the detached posterior hyaloid phase and the retina.

DISEASES OF THE VITREOUS

245

anomalies include congenital cataract, glaucoma, long

and extended ciliary processes, microphthalmos and

vitreous haemorrhage.

Differential diagnosis needs to be made from other

causes of leucocoria especially retinoblastoma,

congenital cataract and retinopathy of prematurity.

Computerised tomography (CT) scanning helps in

diagnosis.

Treatment consists of pars plana lensectomy and

excision of the membranes with anterior vitrectomy

provided the diagnosis is made early. Visual prognosis

is often poor.

Inflammatory vitreous opacities. These consist of

Fig. 10.2. Posterior vitreous detachment with

exudates poured into the vitreous in patients with

synchysis and synersis.

anterior uveitis (iridocyclitis), posterior uveitis

(choroiditis), pars planitis, pan uveitis and

A ring-like opacity (Weiss ring or Fuchs ring),

endophthalmitis.

Vitreous aggregates and condensation with

representing a ring of attachment of vitreous to the

liquefaction. It is the commonest cause of vitreous

optic disc, is pathognomic of PVD.

opacities. Condensation of the collagen fibrillar

Complications of PVD. These include retinal breaks,

network is a feature of the vitreous degeneration

vitreous haemorrhage, retinal haemorrhages and

which may be senile, myopic, post-traumatic or post-

cystoid maculopathy.

inflammatory in origin.

2. Detachment of the vitreous base and the

Amyloid degeneration. It is a rare condition in which

anterior vitreous

amorphous amyloid material is deposited in the

It usually occurs following blunt trauma. It may be

vitreous as a part of the generalised amyloidosis.

associated with vitreous haemorrhage, anterior retinal

These vitreous opacities are linear with footplate

dialysis and dislocation of crystalline lens.

attachments to the retina and the posterior lens

surface.

VITREOUS OPACITIES

Asteroid hyalosis. It is characterised by small, white

rounded bodies suspended in the vitreous gel. These

Since vitreous is a transparent structure, any relatively

are formed due to accumulation of calcium containing

non-transparent structure present in it will form an

lipids. Asteroid hyalosis is a unilateral, asymptomatic

opacity and cause symptoms of floaters. Common

condition usually seen in old patients with healthy

conditions associated with vitreous opacities are

vitreous. There is a genetic relationship between this

described below.

condition, diabetes and hypercholesterolaemia. The

Muscae volitantes. These are physiological opacities

genesis is unknown and there is no effective

and represent the residues of primitive hyaloid

treatment.

vasculature. Patient perceives them as fine dots and

Synchysis scintillans. In this condition, vitreous is

filaments, which often drift in and out of the visual

laden with small white angular and crystalline bodies

field, against a bright background (e.g., clear blue

formed of cholesterol. It affects the damaged eyes

sky).

which have suffered from trauma, vitreous

Persistent hyperplastic primary vitreous (PHPV)

haemorrhage or inflammatory disease in the past. In

results from failure of the primary vitreous structure

this condition vitreous is liquid and so, the crystals

to regress combined with the hypoplasia of the

sink to the bottom, but are stirred up with every

posterior portion of vascular meshwork.

movement to settle down again with every pause.

Clinically it is characterized by a white pupillary reflex

This phenomenon appears as a beautiful shower of

(leucocoria) seen shortly after birth. Associated

golden rain on ophthalmoscopic examination. Since

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Comprehensive OPHTHALMOLOGY

the condition occurs in damaged eye, it may occur at

haemorrhages and no red glow in a large

any age. The condition is generally symptomless, but

haemorrhage.

untreatable.

Direct and indirect ophthalmoscopy may show

Red cell opacities. These are caused by small

presence of blood in the vitreous cavity.

Ultrasonography with B-scan is particularly

vitreous haemorrhages or leftouts of the massive

vitreous haemorrhage.

helpful in diagnosing vitreous haemorrhage.

Tumour cells opacities. These may be seen as free-

Fate of vitreous haemorrhage

floating opacities in some patients with

1. Complete absorption may occur without

retinoblastoma, and reticulum cell sarcoma.

organization and the vitreous becomes clear

within 4-8 weeks.

VITREOUS HAEMORRHAGE

2. Organization of haemorrhage with formation of a

Vitreous haemorrhage usually occurs from the retinal

yellowish-white debris occurs in persistent or

vessels and may present as pre-retinal (sub-hyaloid)

recurrent bleeding.

or an intragel haemorrhage. The intragel haemorrhage

3. Complications like vitreous liquefaction,

may involve anterior, middle, posterior or the whole

degeneration and khaki cell glaucoma (in aphakia)

vitreous body.

may occur.

Causes

4. Retinitis proliferans may occur which may be

complicated by tractional retinal detachment.

Causes of vitreous haemorrhage are as follows:

1. Spontaneous vitreous haemorrhage from retinal

Treatment

breaks especially those associated with PVD.

1. Conservative treatment consists of bed rest,

2. Trauma to eye, which may be blunt or perforating

elevation of patient’s head and bilateral eye

(with or without retained intraocular foreign body)

patches. This will allow the blood to settle down.

in nature.

2. Treatment of the cause. Once the blood settles

3. Inflammatory diseases such as erosion of the

down, indirect ophthalmoscopy should be

vessels in acute chorioretinitis and periphlebitis

performed to locate and further manage the

retinae primary or secondary to uveitis.

causative lesion such as a retinal break, phlebitis,

4. Vascular disorders e.g., hypertensive retinopathy,

proliferative retinopathy, etc.

and central retinal vein occlusion.

3. Vitrectomy by pars plana route should be

5. Metabolic diseases such as diabetic retinopathy.

considered to clear the vitreous, if the

6. Blood dyscrasias e.g., retinopathy of anaemia,

haemorrhage is not absorbed after 3 months.

leukaemias, polycythemias and sickle-cell

retinopathy.

VITREO-RETINAL DEGENERATIONS

7. Bleeding disorders e.g., purpura, haemophilia and

See page 270.

scurvy.

8. Neoplasms. Vitreous haemorrhage may occur from

VITRECTOMY

rupture of vessels due to acute necrosis in

tumours like retinoblastoma.

Surgical removal of the vitreous is now not an

9. Idiopathic

infrequently performed procedure.

Clinical features

TYPES

Symptoms. Sudden development of floaters occurs

1. Anterior vitrectomy. It refers to removal of

when the vitreous haemorrhage is small. In massive

anterior part of the vitreous.

vitreous haemorrhage, patient develops sudden

2. Core vitrectomy. It refers to removal of the central

painless loss of vision.

bulk of the vitreous. It is usually indicated in

Signs

endophthalmitis.

Distant direct ophthalmoscopy reveals black

3. Subtotal and total vitrectomy. In it almost whole

shadows against the red glow in small

of the vitreous is removed.

DISEASES OF THE VITREOUS

247

TECHNIQUES

2. Divided system approach is the most commonly

employed technique in modern vitrectomy. In this

Open-sky vitrectomy

technique three separate incisions are given in pars

This technique is employed to perform only anterior

plana region. That is why the procedure is also called

vitrectomy.

three-port pars plana vitrectomy. The cutting and

Indications

aspiration functions are contained in one probe,

Vitreous loss during cataract extraction.

illumination is provided by a separate fiberoptic probe

Aphakic keratoplasty.

and infusion is provided by a cannula introduced

Anterior chamber reconstruction after perforating

through the third pars plana incision (Fig. 10.3).

trauma with vitreous loss.

Removal of subluxated and anteriorly dislocated

lens.

Surgical technique. Open sky vitrectomy is performed

through the primary wound to manage the disturbed

vitreous during cataract surgery or aphakic

keratoplasty. It should be performed using an

automated vitrectomy machine. However, if the

vitrectomy machine is not available, it can be

performed with the help of a triangular cellulose

sponge and de Wecker’s scissors

(sponge

vitrectomy).

Closed vitrectomy (Pars plana vitrectomy)

Pars plana approach is employed to perform core

vitrectomy, subtotal and total vitrectomy.

Indications

Endophthalmitis with vitreous abscess.

Vitreous haemorrhage.

Proliferative retinopathies such as those

associated with diabetes, Eales’ disease,

retinopathy of prematurity and retinitis proliferans.

Complicated cases of retinal detachment such as

Fig. 10.3. Three-port pars plana vitrectomy using

divided system approach

those associated with giant retinal tears, retinal

dialysis and massive vitreous traction.

Advantages of divided system approach include

Removal of intraocular foreign bodies.

smaller instruments, easy handling, improved

Removal of dropped nucleus or intraocular lens

visualization, use of bimanual technique and adequate

from the vitreous cavity.

infusion by separate cannula.

Persistent primary hyperplastic vitreous.

Vitreous membranes and bands.

VITREOUS SUBSTITUTES

Surgical techniques

Vitreous substitutes or the so called temponading

Pars plana vitrectomy is a highly sophisticated

agents are used in vitreo-retinal surgery to:

microsurgery which can be performed by using two

Restore intraocular pressure and

type of systems:

Provide intraocular tamponade

1. Full function system vitrectomy is now-a-days

An ideal vitreous substitute should be:

sparingly used. It employs a multifunction system

Having a high surface tension,

that comprises vitreous infusion, suction, cutter and

Optically clear, and

illumination (VISC), all in one.

Biologically inert.

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Comprehensive OPHTHALMOLOGY

Currently used vitreous substitutes in the absence

Perfluoropropane. It quadruples its volume

of an ideal substitute are:

and lasts for 28 days.

1. Air is commonly used internal temponade in

4. Perflurocarbon liquids (PFCL) are heavy liquids

uncomplicated cases. It is absorbed within

which are mainly used:

days.

To remove dropped nucleus or IOL from the

2. Physiological solutions such as Ringer’s lactate

vitreous cavity,

or balanced salt solution (BSS) can be used as

substitute after vitrectomy for endophthalmitis

To unfold a giant retinal tear, and

or uncomplicated vitreous haemorrhage.

To stabilize the posterior retina during peeling

3. Expanding gases are preferred over air in complex

of the epiretinal memebrane.

cases requiring prolonged intraocular temponade.

5. Silicone oils allow more controlled retinal

They are used as 40% mixture with air examples

are:

manipulation during operation and can be used

Sulphur hexafluoride

(SF₆). It doubles its

for prolonged intraocular temponade after retinal

volume and lasts for 10 days.

detachment surgery.

Diseases of

CHAPT 1

the Retina

APPLIED ANATOMY

Diabetic retinopathy

Hypertensive retinopathy

CONGENITAL AND DEVELOPMENTAL

Sickle cell retinopathy

DISORDERS

Retinopathy of prematurity

TRAUMATIC LESIONS

Retinal telengiectasias

INFLAMMATORY DISORDERS

Ocular ischaemic syndrome

Retinitis

DYSTROPHIES AND DEGENERATIONS

Periphlebitis retinae

MACULAR DISORDERS

VASCULAR DISORDERS

RETINAL DETACHMENT

Retinal artery occlusions

Retinal vein occlusions

TUMOURS

layers terminate except the nerve fibres, which pass

APPLIED ANATOMY

through the lamina cribrosa to run into the optic

nerve. A depression seen in the disc is called the

Retina, the innermost tunic of the eyeball, is a thin,

physiological cup. The central retinal artery and vein

delicate and transparent membrane. It is the most

emerge through the centre of this cup.

highly-developed tissue of the eye. It appears

Macula lutea. It is also called the yellow spot. It is

purplish-red due to the visual purple of the rods and

comparatively deeper red than the surrounding

underlying vascular choroid.

fundus and is situated at the posterior pole temporal

Gross anatomy

to the optic disc. It is about 5.5 mm in diameter. Fovea

Retina extends from the optic disc to the ora serrata.

centralis is the central depressed part of the macula.

It is about 1.5 mm in diameter and is the most sensitive

Grossly it is divided into two distinct regions:

part of the retina. In its centre is a shining pit called

posterior pole and peripheral retina separated by the

foveola (0.35-mm diameter) which is situated about 2

so called retinal equator.

disc diameters (3 mm) away from the temporal margin

Retinal equator is an imaginary line which is

of the disc and about 1 mm below the horizontal

considered to lie in line with the exit of the four vena

meridian. An area about 0.8 mm in diameter (including

verticose.

foveola and some surrounding area) does not contain

Posterior pole refers to the area of the retina

any retinal capillaries and is called foveal avascular

posterior to the retinal equator. The posterior pole of

zone (FAZ). Surrounding the fovea are the parafoveal

the retina includes two distinct areas: the optic disc

and perifoveal areas.

and macula lutea (Fig. 11.1). Posterior pole of the retina

Peripheral retina refers to the area bounded

is best examined by slit-lamp indirect biomicroscopy

posteriorly by the retinal equator and anteriorly by

using +78D and +90D lens and direct ophthalmoscopy.

the ora serrata. Peripheral retina is best examined with

Optic disc. It is a pink coloured, well-defined circular

indirect ophthalmoscopy and by the use of Goldman

area of 1.5-mm diameter. At the optic disc all the retinal

three mirror contact lens.

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Comprehensive OPHTHALMOLOGY

Ora serrata. It is the serrated peripheral margin where

the retina ends. Here the retina is firmly attached both

to the vitreous and the choroid. The pars plana

extends anteriorly from the ora serrata.

Microscopic structure

Retina consists of 3 types of cells and their synapses

arranged (from without inward) in the following ten

layers (Fig. 11.2):

1. Pigment epithelium. It is the outermost layer of

retina. It consists of a single layer of cells

containing pigment. It is firmly adherent to the

underlying basal lamina (Bruch’s membrane) of

the choroid.

2. Layer of rods and cones. Rods and cones are the

end organs of vision and are also known as

photoreceptors. Layer of rods and cones contains

only the outer segments of photoreceptor cells

arranged in a palisade manner. There are about

Fig. 11.1. Gross anatomy of the retina: A, Parts of retina

120 millions rods and 6.5 millions cones. Rods

in horizontal section at the level of fovea; B, Diagramma-

contain a photosensitive substance visual purple

tic fundus view; C, Fundus photograph.

(rhodopsin) and subserve the peripheral vision

Inner nuclear layer. It mainly consists of cell

and vision of low illumination (scotopic vision).

bodies of bipolar cells. It also contains cell

Cones also contain a photosensitive substance

bodies of horizontal amacrine and Muller’s cells

and are primarily responsible for highly

and capillaries of central artery of retina. The

discriminatory central vision

(photopic vision)

bipolar cells constitute the first order neurons.

and colour vision.

Inner plexiform layer. It essentially consists of

External limiting membrane. It is a fenesterated

connections between the axons of bipolar cells

membrane, through which pass processes of

dendrites of the ganglion cells, and processes

the rods and cones.

of amacrine cells.

Outer nuclear layer. It consists of nuclei of the

Ganglion cell layer. It mainly contains the cell

rods and cones.

bodies of ganglion cells

(the second order

Outer plexiform layer. It consists of connections

of rod spherules and cone pedicles with the

neurons of visual 7pathway). There are two

dendrites of bipolar cells and horizontal cells.

types of ganglion cells. The midget ganglion

DISEASES OF THE RETINA

251

Fig. 11.2. Microscopic structure of the retina.

cells are present in the macular region and the

Its central part (foveola) largely consists of cones

dendrite of each such cell synapses with the

and their nuclei covered by a thin internal limiting

axon of single bipolar cell. Polysynaptic

membrane. All other retinal layers are absent in this

region. In the foveal region surrounding the foveola,

ganglion cells lie predominantly in peripheral

the cone axons are arranged obliquely (Henle’s layer)

retina and each such cell may synapse with

to reach the margin of the fovea.

upto a hundred bipolar cells.

Nerve fibre layer (stratum opticum) consists of

Functional divisions of retina

axons of the ganglion cells, which pass through

Functionally retina can be divided into temporal

the lamina cribrosa to form the optic nerve. For

retina and nasal retina by a line drawn vertically

distribution and arrangement of retinal nerve

through the centre of fovea. Nerve fibres arising from

fibres see Figs. 9.11 and 9.12, respectively and

temporal retina pass through the optic nerve and optic

page 216.

tract of the same side to terminate in the ipsilateral

10. Internal limiting membrane. It is the innermost

geniculate body while the nerve fibres originating

layer and separates the retina from vitreous. It

from the nasal retina after passing through the optic

is formed by the union of terminal expansions

nerve cross in the optic chiasma and travel through

of the Muller’s fibres, and is essentially a

the contralateral optic tract to terminate in the

basement membrane.

contralateral geniculate body.

Structure of fovea centralis

Blood supply

In this area (Fig. 11.3), there are no rods, cones are

Outer four layers of the retina, viz, pigment

tightly packed and other layers of retina are very thin.

epithelium, layer of rods and cones, external

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Comprehensive OPHTHALMOLOGY

2. Anomalies of the nerve fibres e.g., medullated

(opaque) nerve fibres.

3. Anomalies of vascular elements, such as

persistent hyaloid artery and congenital tortuosity

of retinal vessels.

4. Anomalies of the retina proper. These include

albinism, congenital night blindness, congenital

day blindness, Oguchi’s disease, congenital

retinal cyst, congenital retinal detachment and

coloboma of the fundus.

5. Congenital anomalies of the macula are aplasia,

hypoplasia and coloboma.

A few important congenital disorders are

described briefly.

COLOBOMA OF THE OPTIC DISC

It results from the failure in closure of the embryonic

fissure. It occurs in two forms. The minor defect is

more common and manifests as inferior crescent,

usually in association with hypermetropic or

astigmatic refractive error. The fully-developed

Fig. 11.3. Microscopic structure of the fovea centralis.

coloboma typically presents inferonasally as a very

limiting membrane and outer nuclear layer get

large whitish excavation, which apparently looks as

their nutrition from the choroidal vessels.

the optic disc. The actual optic disc is seen as a linear

Inner six layers get their supply from the central

horizontal pinkish band confined to a small superior

retinal artery, which is a branch of the ophthalmic

wedge. Defective vision and a superior visual field

artery.

defect is usually associated.

Central retinal artery emerges from centre of the

physiological cup of the optic disc and divides

DRUSEN OF THE OPTIC DISC

into four branches, namely the superior-nasal,

Drusens are intrapapillary refractile bodies, which

superior-temporal, inferior-nasal and inferior-

usually lie deep beneath the surface of the disc tissue

temporal. These are end arteries i.e., they do not

in childhood and emerge out by the early teens. Thus,

anastomose with each other.

in children they present as pseudo-papilloedema and

The retinal veins. These follow the pattern of the

by teens they can be recognised ophthalmoscopically

retinal arteries. The central retinal vein drains into

as waxy pea-like irregular refractile bodies.

the cavernous sinus directly or through the

superior ophthalmic vein. The only place where

HYPOPLASIA OF OPTIC DISC

the retinal system anastomosis with ciliary system

is in the region of lamina cribrosa.

Hypoplasia of the optic nerve may occur as an isolated

anomaly or in association with other anomalies of

central nervous system. The condition is bilateral in

CONGENITAL AND

60 per cent of cases. It is associated with maternal

DEVELOPMENTAL DISORDERS

alcohol use, diabetes and intake of certain drugs in

pregnancy. It forms a significant cause of blindness

CLASSIFICATION

at birth in developed countries. Diagnosis of mild

1. Anomalies of the optic disc. These include

cases presents little difficulty. In typical cases the

crescents, situs inversus, congenital pigmentation,

disc is small and surrounded by a yellowish and a

coloboma, drusen and hypoplasia of the optic disc.

pigmented ring; referred to as ‘double ring sign’.

DISEASES OF THE RETINA

253

MEDULLATED NERVE FIBRES

Mittendorf dot represents remnant of the anterior

These, also known as opaque nerve fibres, represent

end of hyaloid artery, attached to the posterior lens

myelination of nerve fibres of the retina. Normally,

capsule. It is usually associated with a posterior polar

the medullation of optic nerve proceeds from brain

cataract.

downwards to the eyeball and stops at the level of

lamina cribrosa. Occasionally the process of

myelination continues after birth for an invariable

INFLAMMATORY DISORDERS

distance in the nerve fibre layer of retina beyond the

OF THE RETINA

optic disc on ophthalmoscopic examination. These

appear as a whitish patch with feathery margins,

These may present as retinitis

(pure retinal

usually present adjoining the disc margin. The

inflammation), chorioretinitis (inflammation of retina

traversing retinal vessels are partially concealed by

and choroid), neuroretinitis (inflammation of optic

the opaque nerve fibres (Fig. 11.4). Such a lesion,

disc and surrounding retina), or retinal vasculitis

characteristically, exhibits enlargement of blind spot

(inflammation of the retinal vessels).

on visual field charting. The medullary sheaths

disappear in demyelinating disorders and optic

RETINITIS

atrophy (due to any cause) and thus no trace of this

I. Non-specific retinitis. It is caused by pyogenic

abnormality is left behind.

organisms and may be either acute or subacute.

1. Acute purulent retinitis. It occurs as metastatic

infection in patients with pyaemia. The infection

usually involves the surrounding structures and

soon converts into metastatic endophthalmitis or

even panophthalmitis.

2. Subacute retinitis of Roth. It typically occurs in

patients suffering from subacute bacterial

endocarditis

(SABE). It is characterised by

multiple superficial retinal haemorrhages, involving

posterior part of the fundus. Most of the

haemorrhages have a white spot in the centre

(Roth’s spots). Vision may be blurred due to

involvement of the macular region or due to

associated papillitis.

II. Specific retinitis. It may be bacterial (tuberculosis,

leprosy, syphilis and actinomycosis), viral

(cytomegalic inclusion disease, rubella, herpes

Fig. 11.4. Opaque nerve fibres.

zoster), mycotic, rickettsial or parasitic in origin.

PERSISTENT HYALOID ARTERY

Cytomegalo virus (CMV) retinitis (Fig. 11.5), zoster

retinitis, progressive outer retinal necrosis (PORN)

Congenital remnants of the hyaloid arterial system

caused by an aggressive varient of varicella zoster

may persist in different forms.

virus, and acute retinal necrosis (ARN) caused by

Bergmester’s papilla refers to the flake of glial tissue

herpes simplex virus II (in patients under the age of

projecting from the optic disc. It is the commonest

congenital anomaly of the hyaloid system.

15 years) and by varicella zoster virus and herpes

Vascular loop or a thread of obliterated vessel may

simplex virus-I (in older individuals) have become

sometimes be seen running forward into the vitreous.

more conspicuous in patients with AIDS (HIV

It may even be reaching up to the back of the lens.

infection).

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Comprehensive OPHTHALMOLOGY

Fig.

11.5. Fundus photograph showing typical

cytomegalovirus (CMV) retinitis in a patient with AIDS.

Note white necrotic retina associated with retinal

Fig. 11.6. Fundus photograph of a patient with Eales’

haemorrhages.

di-sease (stage of inflammation). Note venous congestion,

perivascular exudates and sheets of haemorrhages pr-esent

near the affected veins.

RETINAL VASCULITIS

Inflammation of the retinal vessels may be primary

3. Stage of retinal neovascularization is marked by

(Eales’ disease) or secondary to uveitis.

development of abnormal fragile vessels at the

junction of perfused and non-perfused retina.

Eales’ disease

Bleeding from these vessels leads to recurrent

It is an idiopathic inflammation of the peripheral retinal

vitreous haemorrhage.

veins. It is characterised by recurrent vitreous

4. Stage of sequelae is characterized by development

haemorrhage; so also referred to as primary vitreous

of complications such as proliferative

haemorrhage.

vitreoretinopathy, tractional retinal detachment,

Etiology. It is not known exactly. Many workers

rubeosis iridis and neovascular glaucoma.

consider it to be a hypersensitivity reaction to

Treatment of Eales’ disease comprises:

tubercular proteins.

1. Medical treatment. Course of oral corticosteroids

Clinical features. It is a bilateral disease, typically

for extended periods is the main stay of treatment

affecting young adult males. The common presenting

during active inflammation. A course of

symptoms are sudden appearance of floaters (black

antitubercular therapy has also been

recommended in selective cases.

spots) in front of the eye or painless loss of vision

2. Laser photocoagulation of the retina is indicated

due to vitreous haemorrhage. The haemorrhage clears

in stage of neovascularizion.

up but recurrences are very common.

3. Vitreoretinal surgery is required for non-

Clinical course of the Eales’ disease can be described

resolving vitreous haemorrhage and tractional

in four stages:

retinal detachment.

1. Stage of inflammation (Fig. 11.6). The affected

peripheral veins are congested and perivascular

exudates and sheathing are seen along their

VASCULAR DISORDERS OF

surface. Superficial haemorrhages ranging from

RETINA

flame-shaped to sheets of haemorrhages may be

present near the affected veins.

Common vascular disorders of retina include: retinal

2. Stage of ischaemia is characterized by obliteration

artery occlusions, retinal vein occlusions, diabetic

of the involved vessels and development of

retinopathy, hypertensive retinopathy, sickle cell

avascular areas in the periphery as evidenced on

retinopathy, retinopathy of prematurity and retinal

fundus fluorescein angiography.

telangiectasia.

DISEASES OF THE RETINA

255

RETINAL ARTERY OCCLUSION

Etiology

Occlusive disorders of retinal vessels are more

common in patients suffering from hypertension and

other cardiovascular diseases. Common causes of

retinal artery occlusion are:

Atherosclerosis-related thrombosis at the level

of lamina cribrosa is the most common cause

(75%) of CRAO.

Emboli from the carotid artery and those of

cardiac origin account for about 20% cases of

CRAO.

Retinal arteritis with obliteration

(associated

with giant cell arteritis) and periarteritis (associated

with polyarteritis nodosa, systemic lupus erythema-

tosus, Wegner’s granulomatosis and scleroderma)

are other causes of CRAO.

Angiospasm is a rare cause of retinal artery

Fig. 11.7. Fundus photograph showing marked retinal pa-llor

occlusion. It is commonly associated with

in acute central retinal artery occlusion (CRAO) with sparing

amaurosis.

of the territory supplied by cilioretinal artery.

Raised intraocular pressure may occasionally be

associated with obstruction of retinal arteries for

2. Branch retinal artery occlusion (BRAO). It usually

example due to tight encirclage in retinal

occurs following lodgement of embolus at a

detachment surgery.

bifurcation. Retina distal to occlusion becomes

Thrombophilic disorders such as inherited

oedematous with narrowed arterioles (Fig. 11.8). Later

defects of anticoagulants may occasionally be

on the involved area is atrophied leading to permanent

associated with CRAO in young individuals.

sectoral visual field defect.

Clinical features

Clinically retinal artery occlusion may present as

central retinal artery occlusion or branch artery

occlusion. It is more common in males than females.

It is usually unilateral but rarely may be bilateral (1 to

2% cases).

1. Central retinal artery occlusion (CRAO). It occurs

due to obstruction at the level of lamina cribrosa.

Symptoms. Patient complains of sudden painless loss

of vision.

Signs. Direct pupillary light reflex is absent. On

ophthalmoscopic examination retinal arteries are

markedly narrowed but retinal veins look almost

normal. Retina becomes milky white due to oedema.

Central part of the macular area shows cherry-red

spot due to vascular choroid shining through the thin

retina of this region. In eyes with a cilioretinal artery,

part of the macular will remain normal (Fig. 11.7). Blood

column within the retinal veins is segmented (cattle-

trucking). After a few weeks the oedema subsides,

Fig. 11.8. Superotemporal branch retinal artery occlusion

and atrophic changes occur which include grossly

(BRAO). Note retinal pallor in superotemporal area and

attenuated thread-like arteries and consecutive optic

whitish emboli on the optic disc and in superior temporal

atrophy (see page 302, 303 Fig 12.12B).

branch of retinal artery.

256

Comprehensive OPHTHALMOLOGY

Management

Non-ischaemic CRVO

Treatment of central retinal artery occlusion is

Non-ischaemic CRVO (venous stasis retinopathy)

unsatisfactory, as retinal tissue cannot survive

is the most common clinical variety (75%). It is

ischaemia for more than a few hours. The emergency

characterised by mild to moderate visual loss. Fundus

treatment should include:

examination in early cases (Fig. 11.9) reveals mild

1. Immediate lowering of intraocular pressure by

venous congestion and tortuosity, a few superficial

intravenous mannitol and intermittent ocular

flame-shaped haemorrhages more in the peripheral

massage. It may aid the arterial perfusion and

than the posterior retina, mild papilloedema and mild

also help in dislodging the embolus. Even

or no macular oedema. In late stages (after 6-9

paracentesis of anterior chamber has been

months), there appears sheathing around the main

recommended for this purpose.

veins, and a few cilioretinal collaterals around the

2. Vasodilators and inhalation of a mixture of 5

disc. Retinal haemorrhages are partly absorbed.

percent carbon dioxide and 95 percent oxygen

Macula may show chronic cystoid oedema in

(practically patient should be asked to breathe in

moderate cases or may be normal in mild cases.

a polythene bag) may help by relieving element

Treatment is usually not required. The condition

of angiospasm.

resolves with almost normal vision in about 50 percent

3. Anticoagulants may be helpful in some cases.

cases. Visual loss in rest of the cases is due to chronic

4. Intravenous steroids are indicated in patients

cystoid macular oedema, for which no treatment is

with giant cell arteritis.

effective. However, a course of oral steroids for 8-12

Complications

weeks may be effective.

In some cases ‘neovascular glaucoma’ with incidence

varying from 1% to 5%, may occur as a delayed

complication of central retinal artery occlusion.

RETINAL VEIN OCCLUSION

It is more common than the artery occlusion. It

typically affects elderly patients in sixth or seventh

decade of life.

Etiology

1. Pressure on the vein by a sclerotic retinal artery

where the two share a common adventitia (e.g.,

just behind the lamina cribrosa and at

arteriovenous crossings).

2. Hyperviscosity of blood as in polycythemia,

hyperlipidemia and macroglobulinemia.

3. Periphlebitis retinae which can be central or

peripheral.

4. Raised introcular pressure. Central retinal vein

occlusion is more common in patients with primary

Fig. 11.9. Central retinal vein occlusion (non-ischaemic)

open-angle glaucoma.

5. Local causes are orbital cellulitis, facial erysipelas

Ischaemic CRVO

and cavernous sinus thrombosis.

Ischaemic CRVO (Haemorrhagic retinopathy) refers

Classification

to acute (sudden) complete occlusion of central retinal

1. Central retinal vein occlusion (CRVO) It may be

vein. It is characterised by marked sudden visual loss.

non-ischaemic CRVO (venous stasis retinopathy)

Fundus examination in early cases (Fig. 11.10) reveals

or ischaemic CRVO (haemorrhagic retinopathy).

massive engorgement, congestion and tortuousity

2. Branch retinal vein occlusion (BRVO)

of retinal veins, massive retinal haemorrhages (almost

DISEASES OF THE RETINA

257

A-V crossing causing quadrantic occlusion and

small macular or peripheral branch occlusion. In

branch vein occlusion oedema and haemorrhages are

limited to the area drained by the affected vein (Fig.

11.11). Vision is affected only when the macular area

is involved. Secondary glaucoma occurs rarely in

these cases. Chronic macular oedema and

neovasculari-sation may occur as complications of

BRVO in about one third cases.

Treatment. Grid photocoagulation may be required

in patients with chronic macular oedema. In patients

with neovascularisation, scatter photocoagulation

should be carried out.

HYPERTENSIVE RETINOPATHY

It refers to fundus changes occurring in patients

Fig. 11.10. Central retinal vein occlusion (ischaemic)

suffering from systemic hypertension.

whole fundus is full of haemorrhages giving a

Pathogenesis

‘splashed-tomato’ appearance), numerous soft

exudates, and papilloedema. Macular area is full of

Three factors which play role in the pathogenesis of

haemorrhages and is severely oedematous. In late

hypertensive retinopathy are vasoconstriction,

stages, marked sheathing around veins and

arteriosclerosis and increased vascular permeability.

collaterals

seen around the disc.

1. Vasoconstriction. Primary response of the retinal

Neovascularisation may be seen at the disc (NVD) or

arterioles to raised blood pressure is narrowing

in the periphery (NVE). Macula shows marked

(vasoconstriction) and is related to the severity of

pigmentary changes and chronic cystoid oedema.

hypertension. It occurs in pure form in young

The pathognomic features for differentiating

individuals, but is affected by the pre-existing

ischaemic CRVO from non-ischaemic CRVO are

involutional sclerosis in older patients.

presence of relative afferent pupillary defect (RAPD),

visual field defects and reduced amplitude of b-wave

of electroretinogram (ERG).

Complications. Rubeosis iridis and neovascular

glaucoma (NVG) occur in more than 50 percent cases

within 3 months (so also called as 90 days glaucoma),

A few cases develop vitreous haemorrhage and

proliferative retinopathy.

Treatment. Panretinal photocoagulation (PRP) or

cryo-application, if the media is hazy, may be required

to prevent neovascular glaucoma in patients with

widespread capillary occlusion. Photocoagulation

should be carried out when most of the intraretinal

blood is absorbed, which usually takes about 3-4

months.

Branch retinal vein occlusion (BRVO)

It is more common than the central retinal vein

occlusion. It may occur at the following sites: main

branch at the disc margin causing hemispheric

Fig. 11.11. Superotemporal branch retinal vein

occlusion, major branch vein away from the disc, at

occlusion (BRVO).

258

Comprehensive OPHTHALMOLOGY

2. Arteriosclerotic changes which manifest as

Grade II (Fig. 11.12B). It comprises marked

changes in arteriolar reflex and A-V nipping result

generalized narrowing and focal attenuation of

from thickening of the vessel wall and are a reflection

arterioles associated with deflection of veins at

of the duration of hypertension. In older patients

arteriovenous crossings (Salus’ sign).

arteriosclerotic changes may preexist due to

involutional sclerosis.

Grade III (Fig. 11.12C). This consists of Grade II

3. Increased vascular permeability results from

changes plus copper-wiring of arterioles, banking

hypoxia and is responsible for haemorrhages, exudates

of veins distal to arteriovenous crossings (Bonnet

and focal retinal oedema.

sign), tapering of veins on either side of the

Grading of hypertensive retinopathy

crossings (Gunn sign) and right-angle deflection

Keith and Wegner

(1939) have classified

of veins

(Salu’s sign). Flame-shaped

hypertensive retinopathy changes into following four

haemorrhages, cotton-wool spots and hard

grades:

exudates are also present.

Grade I

(Fig.

11.12A). It consists of mild

generalized arteriolar attenuation, particularly of

Grade IV (Fig. 11.12D). This consists of all

small branches, with broadening of the arteriolar

changes of Grade III plus silver-wiring of arterioles

light reflex and vein concealment.

and papilloedema.

Fig. 11.12. Hypertensive retinopathy: A, grade I, B, grade II, C, grade III; D, grade IV.

DISEASES OF THE RETINA

259

Clinical types

characterised by appearance of ‘cotton wool spots’

Clinically, hypertensive retinopathy may occur in four

and superficial haemorrhages. If pregnancy is allowed

circumstances:

to continue, further progression of retinopathy occurs

1. Hypertension with involutionary (senile) sclerosis.

rapidly. Retinal oedema and exudation is usually

When hypertension occurs in elderly patients (after

marked and may be associated with ‘macular star’ or

the age of 50 years) in the presence of involutionary

‘flat macular detachment’. Rarely it may be

sclerosis the fundus changes comprise augmented

complicated by bilateral exudative retinal detachment.

arteriosclerotic retinopathy.

Prognosis for retinal reattachment is good, as it

2. Hypertension without sclerosis. It occurs in young

occurs spontaneously within a few days of

people, where elastic retinal arterioles are exposed to

termination of pregnancy.

raised blood pressure for a short duration. There are

Management. Changes of retinopathy are reversible

few retinal signs. The arterioles are constricted, pale

and disappear after the delivery, unless organic

and straight with acute-angled branching. There are

vascular disease is established. Therefore, in pre-

minimal signs of arteriovenous crossing. Occasionally

organic stage when patient responds well to

small haemorrhages may be found. Exudates and

conservative treatment, the pregnancy may justifiably

papilloedema are never seen.

be continued under close observation. However, the

3. Hypertension with compensatory arteriolar

advent of hypoxic retinopathy (soft exudates, retinal

sclerosis. This condition is seen in young patients

oedema and haemorrhages) should be considered an

with prolonged benign hypertension usually

indication for termination of pregnancy; otherwise,

associated with benign nephrosclerosis. The young

permanent visual loss or even loss of life (of both

arterioles respond by proliferative and fibrous

mother and foetus) may occur.

changes in the media (compensatory arteriolar

DIABETIC RETINOPATHY

sclerosis). Advanced fundus changes in these

It refers to retinal changes seen in patients with

patients have been described as ‘albuminuric or renal

diabetes mellitus. With increase in the life expectancy

retinopathy’.

of diabetics, the incidence of diabetic retinopathy (DR)

4. Malignant hypertension. It is not a separate

has increased. In Western countries, it is the leading

variety of hypertension, but is an expression of its

cause of blindness.

rapid progression to a serious degree in a patient

with relatively young arterioles undefended by

Etiopathogenesis

fibrosis. The fundus picture is characterised by

Risk factors associated with occurence of DR are:

marked arteriolar narrowing, papilloedema (an

1. Duration of diabetes is the most important

essential feature of malignant hypertension), retinal

determining factor. Roughly 50 percent of patients

oedema over the posterior pole, clusters of superficial

develop DR after 10 years, 70 percent after 20

flame-shaped haemorrhages and an abundance of

years and 90 percent after 30 years of onset of

cotton wool patches.

the disease.

2. Sex. Incidence is more in females than males (4:3).

RETINOPATHY IN PREGNANCY-INDUCED

3. Poor metabolic control is less important than

HYPERTENSION

duration, but is nevertheless relevant to the

Pregnancy-induced hypertension (PIH), previously

development and progression of DR.

known as ‘toxaemia of pregnancy’, is a disease of

4. Heredity. It is transmitted as a recessive trait

unknown etiology characterised by raised blood

without sex linkage. The effect of heredity is

pressure, proteinuria and generalised oedema. Retinal

more on the proliferative retinopathy.

changes are liable to occur in this condition when

5. Pregnancy may accelerate the changes of diabetic

blood pressure rises above 160/100 mm of Hg and are

retinopathy.

marked when blood pressure rises above 200/130 mm

6. Hypertension, when associated, may also

of Hg. Earliest changes consist of narrowing of nasal

accentuate the changes of diabetic retinopathy.

arterioles, followed by generalised narrowing. Severe

7. Other risk factors include smoking, obesity and

persistent spasm of vessels causes retinal hypoxia

hyperlipidemia.

260

Comprehensive OPHTHALMOLOGY

Pathogenesis. Essentially, it is a microangiopathy

Hard exudates-yellowish-white waxy-looking

affecting retinal precapillary arterioles, capillaries and

patches are arranged in clumps or in circinate

venules. The speculative pathogenesis is depicted

pattern. These are commonly seen in the macular

in the flow- chart (Fig. 11.13).

area.

Retinal oedema characterized by retinal

Vascular changes seen in diabetes mellitus

thickening.

↓

Cotton-wool spots (if > 8, there is high risk of

Thickening of capillary basement membrane

developing PDR).

Capillary endothelial cell damage

Venous abnormalities, beading, looping and

Changes in RBCs

dilatation.

Increased stickiness of platelets

Intraretinal microvascular abnormalities

Loss of capillary pericytes

(IRMA).

Dark-blot haemorrhages representing haemorr-

→ Microvascular occlusion

hagic retinal infarcts.

↓

On the basis of severity of the above findings the

Retinal ischaemia

NPDR has been further classified as under:

↓

1. Mild NPDR (Fig. 11.14A).

→ Capillary leakage

←

At least one microaneurysm or intraretinal

Microaneurysms

←

hemorrhage.

→ Haemorrhage

Hard/soft exudates may or may not be present.

→ Retinal oedema

2. Moderate NPDR (Fig. 11.14B)

→ Hard exudates

Moderate microaneurysms/intraretinal hemorr-

→ Arteriovenous shunts

hage.

(Intraretinal microvascular

Early mild IRMA.

abnormalities — IRMA)

Hard/soft exudates may or may not present.

→ Neovascularisation

3. Severe NPDR. Any one of the following

(4-2-1

Rule) (Fig. 11.14C):

Fig. 11.13. Flowchart depicting pathogenesis of diabetic

retinopathy.

Four quadrants of severe microaneurysms/

intraretinal hemorrhages.

Classification

Two quadrants of venous beading.

Diabetic retinopathy has been variously classified.

One quadrant of IRMA changes.

Presently followed classification is as follows:

4. Very severe NPDR. Any two of the following

Non-proliferative diabetic retinopathy (NPDR)

(4-2-1 Rule) (Fig. 11.14D):

Mild NPDR

Four quadrants of severe microaneurysms/

intraretinal hemorrhages.

Moderate NPDR

Two quadrants of venous beading.

Severe NPDR

One quadrant of IRMA changes.

Very severe NPDR

II. Proliferative diabetic retinopathy (PDR)

III. Diabetic maculopathy

Proliferative diabetic retinopathy (Figs. 11.14 E&F)

IV. Advanced diabetic eye disease (ADED)

develops in more than 50 percent of cases after about

I. Non-proliferative diabetic retinopathy (NPDR)

25 years of the onset of disease. Therefore, it is more

common in patients with juvenile onset diabetes. The

Ophthalmoscopic features of NPDR include:

Microaneurysms in the macular area (the earliest

hallmark of PDR is the occurrence of

detectable lesion).

neovascularisation over the changes of very severe

Retinal haemorrhages both deep (dot and blot

non-proliferative diabetic retinopathy. It is

haemorrhages) and superficial haemorrhages

characterised by proliferation of new vessels from

(flame-shaped).

the capillaries, in the form of neovascularisation at

DISEASES OF THE RETINA

261

the optic disc (NVD) and/or elsewhere (NVE) in the

1. PDR without HRCs (Early PDR) (Fig. 11.14E), and

fundus, usually along the course of the major temporal

2. PDR with HRCs (Advanced PDR). High risk

retinal vessels. These new vessels may proliferate in

characteristics (HRC) of PDR are as follows

the plane of retina or spread into the vitreous as

(Fig. 11.14F):

vascular fronds. Later on condensation of connective

NVD 1/4 to 1/3 of disc area with or without

tissue around the new vessels results in formation of

vitreous haemorrhage

(VH) or pre-retinal

fibrovascular epiretinal membrane. Vitreous

haemorrhage (PRH)

detachment and vitreous haemorrhage may occur in

NVD < 1/4 disc area with VH or PRH

this stage.

NVE > 1/2 disc area with VH or PRH

Types. On the basis of high risk characteristics

(HRCs) described by diabetic retinopathy study

III. Diabetic maculopathy

(DRS) group, the PDR can be further classified as

Changes in macular region need special mention, due

below:

to their effect on vision. These changes may be

Fig. 11.14. Diabetic retinopathy: A, Mild NPDR; B, Moderate NPDR; C, Severe NPDR; D, Very severe NPDR; E, Early

PDR; F, High risk PDR; G, Exudative diabetic maculopathy.

262

Comprehensive OPHTHALMOLOGY

associated with non-proliferative diabetic

Investigations

retinopathy (NPDR) or proliferative diabetic

Urine examination,

retinopathy (PDR). The diabetic macular edema occurs

Blood sugar estimation.

due to increased permeability of the retinal capillaries.

Fundus fluorescein angiography should be carried

It is termed as clinically significant macular edema

out to elucidate areas of neovascularisation,

(CSME) if one of the following three criteria are

leakage and capillary nonperfusion.

present on slit-lamp examination with 90D lens:

Management

Thickening of the retina at or within 500 micron

of the centre of the fovea.

I. Screening for diabetic retinopathy. To prevent

Hard exudate at or within 500 micron of the centre

visual loss occurring from diabetic retinopathy a

of fovea associated with adjacent retinal

periodic follow-up is very important for a timely

thickening.

intervention. The recommendations for periodic

Development of a zone of retinal thickening one

fundus examination are as follows:

disc diameter or larger in size, at least a part of

Every year, till there is no diabetic retinopathy or

which is within one disc diameter of the foveal

there is mild NPDR.

centre.

Every 6 months, in moderate NPDR.

Every 3 months, in severe NPDR.

Clinico-angiographically diabetic maculopathy can be

Every

2 months, in PDR with no high risk

classified into four types:

characteristic.

1. Focal exudative maculopathy (Fig. 11.14G). It is

II. Medical treatment. Besides laser and surgery to

characterised by microaneurysms, haemorrhages,

the eyes (as indicated and described below), the

macular oedema and hard exudates which are usually

medical treatment also plays an essential role. Medical

arranged in a circinate pattern. Fluorescein

treatment for diabetic retinopathy can be discussed

angiography reveals focal leakage with adequate

as:

macular perfusion.

2. Diffuse exudative maculopathy. It is characterised

1. Control of systemic risk factors is known to

influence the occurrence, progression and effect

by diffuse retinal oedema and thickening throughout

of laser treatment on DR. The systemic risk factors

the posterior pole, with relatively few hard exudates.

which need attention are.

Fluorescein angiography reveals diffuse leakage at

Strict metabolic control of blood sugar,

the posterior pole.

Lipid reduction,

3. Ischaemic maculopathy. It occurs due to

Control of associated anaemia, and

microvascular blockage. Clinically it is characterised

Control of associated hypoproteinemia

by marked visual loss with microaneurysms,

2. Role of pharmacological modulation. Pharma-

haemorrhages, mild or no macular oedema and a few

cological inhibition of certain biochemical

hard exudates. Fluorescein angiography shows areas

pathways involved in the pathogenesis of retinal

of non-perfusion which in early cases are in the form

changes in diabetes is being evaluated These

of enlargement of foveal avascular zone (FAZ), later

include:

on areas of capillary dropouts are seen and in

Protein kinase C (PKC) inhbitors,

advanced cases precapillary arterioles are blocked.

Vascular endothelial growth factors (VEGF)

4. Mixed maculopathy. In it combined features of

inhibitors,

ischaemic and exudative maculopathy are present.

Aldose reductase and ACE inhibitors, and

IV. Advanced diabetic eye disease

Antioxidants such as vitamin E

It is the end result of uncontrolled proliferative

3. Role of intravitreal steroids in reducing diabetic

diabetic retinopathy. It is marked by complications

macular oedema is also being stressed recently

such as:

by following modes of administration:

Persistent vitreous haemorrhage,

Flucinolone acetonide intravitreal implant and

Tractional retinal detachment and

Intravitreal injection of triamcinolone

Neovascular glaucoma.

(2 to 4 mg)

DISEASES OF THE RETINA

263

III. Photocoagulation. It remains the mainstay in the

treatment of diabetic retinopathy and maculopathy.

Either argon or diode laser can be used. The protocol

of laser application is different for macula and rest of

the retina as follows (Fig. 11.15):

i. Macular photocoagulation. Macula is treated

by laser only if there is clinically significant

macular oedema

(CSME). Laser treatment is

contraindicated in ischaemic diabetic maculopathy.

In patients with PDR associated with CSME,

macular photo-coagulation should be considered

first i.e., before PRP since the latter may worsen

macular oedema. Macular photocoagulation

includes two techniques:

Focal treatment (Fig. 11.15A) with argon laser

is carried out for all lesions (microaneurysms,

IRMA or short capillary segments) 500-3000

microns from the centre of the macula, believed

to be leaking and causing CSME. Spot size of

100-200 µm of 0.1 second duration is used.

Grid treatment. Grid pattern laser burns are

applied in the macular area for diffuse diabetic

macular oedema (Fig. 11.15B).

ii. Panretinal photocoagulation

(PRP) or scatter

laser consists of 1200-1600 spots, each 500 µm in

size and 0.1 sec. duration. Laser burns are applied

2-3 disc areas from the centre of the macula

extending peripherally to the equator (Fig. 11.15C).

In PRP temporal quadrant of retina is first

coagulated. PRP produces destruction of

ischaemic retina which is responsible for the

production of vasoformative factors.

Indications for PRP are:

PDR with HRCs,

Neovascularization of iris (NVI),

Severe NPDR associated with:

- Poor compliance for follow up,

- Before cataract surgery/YAG capsulotomy,

- Renal failure,

- One-eyed patient, and

- Pregnancy

IV. Surgical treatment. It is required in advanced

cases of PDR. Pars plana vitrectomy is indicated for

dense persistent vitreous haemorrhage, tractional

retinal detachment, and epiretinal membranes.

Fig. 11.15. Protocols of Laser application in diabetic

Associated retinal detachment also needs surgical

retinopathy : A, Focal treatment; B, Grid treatment and;

repair.

C, Panretinal photocoagulation.

264

Comprehensive OPHTHALMOLOGY

SICKLE-CELL RETINOPATHY

are very common. Occasionally large pre-retinal (sub-

Retinal changes in patients suffering from sickle cell

hyaloid) haemorrhages may also be seen.

haemoglobinopathies (abnormal haemoglobins) are

RETINOPATHY OF PREMATURITY

primarily caused by retinal hypoxia; which results

Retinopathy of prematurity (ROP) is a bilateral

from blockage of small blood vessels by the abnormal-

proliferative retinopathy, occurring in premature

shaped rigid red blood cells.

infants with low birth weight who often have been

Clinical features

exposed to high concentration of oxygen. Earlier this

Sickle-cell retinopathy can be divided into five self-

disease was known as retrolental fibroplasia.

explanatory stages as follows:

Etiopathogenesis

1. Stage of peripheral arteriolar occlusion.

Low birth weight and decreased gestational age are

2. Stage of peripheral arteriovenous anastomoses.

now considered the primary causative factors.

3. Stage of neovascularisation.

Supplemental oxygen administration which was for a

4. Stage of vitreous haemorrhage.

long time considered as the important causative factor

5. Stage of vitreoretinal traction bands and tractional

is now considered only a risk factor. Based on the

retinal detachment.

above facts, two important hypothesis are postulated

Treatment

to describe pathogenesis of disease:

Panretinal photocoagulation (PRP) is effective

1. Classical theory postulates that owing to

in regressing the neovascularisation.

exposure to high concentration of oxygen, there

Pars plana vitrectomy is required for vitreoretinal

occurs obliteration of premature retinal vessels.

tractional bands. It should be followed by repair

This is followed by neovascularisation and fibrous

of the retinal detachment, when present.

tissue proliferatiion which ultimately forms a

retrolental mass.

RETINOPATHIES OF BLOOD DYSCRASIAS

2. Spindle cell theory proposed recently postulates

These are seen in patients suffering from anaemias,

the induction of retinal and vitreal

leukaemias and polycythemias.

neovascularization by spindle cell insult in a

premature retina.

Anaemic retinopathy

Clinical features

In anaemia, retinal changes are liable to occur when

haemoglobin level falls by 50 percent and are

The condition has been divided into active ROP and

consistently present when it is below 35 percent (5

cicatricial ROP. Clinically the evolution of the active

gm%). Anaemic retinopathy is characterised by pale

ROP has been divided into five stages (Fig. 11.16):

arterioles and a pale general background of the

Stage 1. It is characterised by formation of a

fundus. Retinal veins are dilated. Superficial retinal

demarcation line seen at the edge of vessels,

and preretinal (subhyaloid) haemorrhages may be

dividing the vascular from the avascular retina.

seen in posterior half of the fundus. A few

Stage 2. The line structure of stage 1 acquires a

haemorrhages have white centres (Roth spots). Rarely,

volume to form a ridge with height and width.

a few soft exudates (cotton-wool patches) may also

Stage 3. It is characterised by a ridge with extra-

be present.

retinal fibrovascular proliferation into the

vitreous. This stage is further subdivided into

Leukaemic retinopathy

mild, moderate and severe, depending on the

It is characterised by pale and orange fundus

amount of fibrovascular proliferation.

background with dilated and tortuous veins. In later

Stage 4a. It includes subtotal retinal detachment

stages, greyish white lines may be seen along the

not involving the macula. It occurs as a result of

course of the veins (due to perivascular leukaemic

exudation from incompetent blood vessels or

infiltration).

traction from the fibrous (cicatricial) tissue.

Arterioles become pale and narrow. Retinal

Stage 4b. It includes subtotal retinal detachment

haemorrhages with typical white centre (Roth spots)

involving the macula.

DISEASES OF THE RETINA

265

Stage 5. It is marked by total retinal detachment

Extent of involvement is denoted by the clock hours

which is always funnel-shaped.

of retinal involvement in the particular zone

(Fig. 11.17).

Retinal area (zones) of involvement in ROP

Plus disease refers to presence of tortuous dilated

The retina is divided into 3 zones. The centre of the

vessels at posterior pole with any stage of ROP.

retinal map for ROP is the optic disc not the macula

as in other retinal charts (Fig. 11.17).

Associated with it is the engorgment and dilatation

Zone I. A circle drawn on the posterior pole, with

of iris vessels, which result in poor pharmacological

dilatation of pupil. Plus diseases signifies a tendency

the optic disc as the centre and twice the disc-

to progression.

macula distance as the radius, constitutes zone I.

Any ROP in this zone is usually very severe

Prethreshold disease is defined as ROP in:

because of a large peripheral area of avascular

Zone I, any stage, or

retina.

Zone II, stage 2 with plus component, or

Zone II. A circle is drawn with the optic disc as

Zone II or III, stage 3 with plus component but

the centre and disc to nasal ora serrata as the

not reaching threshold clock hours.

radius. The area between zone I and this boundary

constitutes zone II.

Note: Pretheshold ROP needs very close observation

Zone III. The temporal arc of retina left beyond

as it can rapidly progress to threshold, which needs

the radius of zone II is zone III.

prompt treatment.

Fig. 11.16. Stages of retinopathy of prematurity (ROP) : A, stage 1. demarcation line; B, Stage 2-demarcation ridge;

C, Stage 3 - Extraretinal neovascularization and proliferation; D, Stage 4 - Subtotal retinal detachment involving macula;

E, Stage 5 - Total retinal detachment.

266

Comprehensive OPHTHALMOLOGY

temporal ora-serrate. Infants with mature retina does

not require further follow-up.

II. Immature retina is labelled when the vessels are

short of one disc diameter of the nasal or temporal

ora but ROP is not developed yet. Such infants require

further follow-up weekly.

III. Retinopathy of prematurity When ROP is detected

following measures should be taken:

Stage 1 and 2. Since spontaneous regression of

disease occurs in 80 to 90% of cases, so only a

weekly examination is recommended.

Stage 3, threshold disease should be treated by

cryo or laser to prevent progression and to

achieve regression.

Stage 4a. Scleral buckling is recommended in

addition to cryo or laser therapy.

Stage 4b and 5. Vitrectomy needs to be carried

Fig. 11.17. Division of retina into zones (I,II,III) and clock

out in this stage.

hour positions to depict involvement in retinopathy

of prematurity.

Prognosis is poor in stage 4b and 5.

EXUDATIVE RETINOPATHY OF COATS

Threshold disease refers to stage 3 plus disease

Coats’ disease is a severe form of retinal telengiectasia

involving 5 continuous or 8 discontinuous clock

(idiopathic congenital vascular malformation), which

hours. This stage needs laser or cryotherapy in less

typically affects one eye of boys in their first decade

than 72 hours.

of life. In early stages it is characterised by large areas

of intra and subretinal yellowish exudates and

Differential diagnosis

haemorrhages associated with overlying dilated and

Advanced retrolental fibroplasia needs to be

tortuous retinal blood vessels and a number of small

differentiated from other causes of leukocoria (see

aneurysms near the posterior pole and around the

page 282).

disc. It may present with visual loss, strabismus or

Screening and management

leukocoria (whitish pupillary reflex) and thus needs

Treatment of well-established disease is

to be differentiated from retinoblastoma. The

unsatisfactory. Prophylaxis is thus very important.

condition usually progresses to produce exudative

To prevent ROP, the premature newborns should not

retinal detachment and a retrolental mass. In late

be placed in incubator with an O₂ concentration of

stages complicated cataract, uveitis and secondary

more than 30 percent and efforts should be made to

glaucoma occur, which eventually end in phthisis

avoid infection and attacks of apnoea. Further, a

bulbi.

regular screening is very important.

Treatment

All premature babies born at less than or equal to

Photocoagulation or cryotherapy may check

32 weeks of gestational age and those weighing 1500g

progression of the disease if applied in the early stage.

or less should be screened for ROP. The first

However, once the retina is detached the treatment

examination by indirect ophthalmosocpy should be

becomes increasingly difficult and success rate

done between 6 and 7 weeks post-natal age or 34

declines to 33 percent.

weeks post-conceptual age (whichever is earlier). The

further line of action will depend upon the overall

OCULAR ISCHAEMIC SYNDROME

status of the eye as below:

Etiology. Ocular ischaemic syndrome refers to a rare

I. Mature retina is labelled when the vessels have

condition resulting from chronic ocular

reached within one disc diameter of both nasal and

hypoperfusion secondary to carotid artery stenosis.

DISEASES OF THE RETINA

267

Carotid stenosis refers to atherosclerotic occlusive

Cataract may occur as a complication in

carotid artery disease often associated with ulceration

advanced cases.

Neovascular glaucoma is a frequent sequelae to

at the bifurcation of common carotid artery. Risk

anterior segment neovascularization.

factors include male gender, old age (60-90 years),

Fundus examination may reveal:

smoking, for carotid stances hypertension, diabetes

- Venous dilatation with irregular caliber but no

mellitus and hyperlipidaemia. The manifestations of

or only mild tortuosity.

carotid occlusive disease include:

- Retinal arterial narrowing is present.

Amaurosis fugax

(transient retinal ischaemic

- Retina show midperipheral dot and blot

attack),

haemorrhages, microaneurysms and cotton

Retinal artery occlusion (due to embolus),

wool spots.

Transient cerebral ischaemic attacks (TIA),

- Retinal neovascularization is noted in

37%

Stroke, and

cases, which may be in the form of NVD and

Asymetrical diabetic retinopathy.

occasionally NVE.

Clinical features. Ocular ischaemic syndrome is

- Macular oedema is a common complication.

Differential diagnosis. Ocular ischaemic syndrome

usually unilateral (80%), affecting elderly males more

needs to be differentiated from non-ischaemic CRVO,

commonly than females.

diabetic retinopathy and hypertensive retinopathy

Symptoms include:

(Table 11.1). Other rare conditions to be excluded

Loss of vision, which usually progresses gradually

include hyperlipidaemic ophthalmopathy and aortic

over several weeks or months.

arch disease caused by Takayasu arteritis,

Transient black outs (amaurosis fugax) may be

aortoarteritis, atherosclerosis and syphilis.

noted by some patients.

Investigations. In suspected cases the carotid

Pain-ocular or periorbital— may be complained

stenosis can be confirmed by Doppler ultrasound and

by some patients.

magnetic resonance angiography.

Delayed dark adaptation may be noted by a few

Treatment of ocular ischaemic syndrome includes:

patients.

Treatment of neovascular glaucoma (see page

Signs include:

234).

Cornea may show oedema and striae.

Treatment of proliferative retinopathy by PRP

Anterior chamber my reveal faint aqueous flare

(see page 263).

with few, if any, cell (ischaemic pseudoiritis).

Pseudoiritis is treated with topical steroid eye

Pupil may be mid dilated and poorly reacting.

drops.

Iris shows rubeosis iridis

(in

66% cases) and

Treatment of carotid stenosis is medical

atrophic patches.

(antiplatelet therapy, oral anticoagulants) and

surgical (carotid endarterectomy).

Table 11.1. Differential diagnosis of ocular ischaemic syndrome

Condition

Similarities

Differences

1. Non-ischaemic CRVO

Unilateral retinal haemorrhages,

Veins are more tortuous, haemorrhages

venous dilatation and cotton wool

are more numerous, normal retinal

spots

arteriolar perfusion, disc oedema, and

sometimes opticociliary shunt vessels

can be seen on the disc

2. Diabetic retinopathy

Microaneurysms, dot and blot

Usually bilateral, with characteristic hard

haemorrhages, venous dilatation,

exudates

NVD and NVE, cotton wool spots

3. Hypertensive retinopathy

Arteriolar narrowing and focal

Usually bilateral, no marked venous

constriction, retinal haemorrhages

changes, and NVD and NVE.

and cotton wool spots

268

Comprehensive OPHTHALMOLOGY

2. Retinal arterioles are attenuated (narrowed) and

DYSTROPHIES AND

may become thread-like in late stages.

DEGENERATIONS OF RETINA

3. Optic disc becomes pale and waxy in later stages

and ultimately consecutive optic atrophy occurs

A wide variety of dystrophies and degenerations of

(Fig. 11.19).

the retina have been described and variously

4. Other associated changes which may be seen are

classified. These lesions are beyond the scope of

colloid bodies, choroidal sclerosis, cystoid macular

this chapter, only a common retinal dystrophy

oedema, atrophic or cellophane maculopathy.

(retinitis pigmentosa), a few peripheral retinal

degenerations some of the vitreoretinal degenerations

are described here.

Annular or ring-shaped scotoma is a typical feature

which corresponds to the degenerated equatorial zone

RETINITIS PIGMENTOSA

of retina. As the disease progresses, scotoma

This primary pigmentary retinal dystrophy is a

increases anteriorly and posteriorly and ultimately

hereditary disorder predominantly affecting the rods

more than the cones.

Inheritance

Most common mode is autosomal recessive, followed

by autosomal dominant. X-linked recessive is the least

common.

Incidence

It occurs in

5 persons per 1000 of the world

population.

Age. It appears in the childhood and progresses

slowly, often resulting in blindness in advanced

middle age.

Race. No race is known to be exempt or prone to it.

Sex. Males are more commonly affected than

females in a ratio of 3:2.

Laterality. Disease is almost invariably bilateral

Fig. 11.18. Fundus picture of retinitis pigmentosa.

and both the eyes are equally affected.

Clinical features

(A) Visual symptoms

1. Night blindness. It is the characteristic feature

and may present several years before the visible

changes in the retina appear. It occurs due to

degeneration of the rods.

2. Dark adaptation. Light threshold of the peripheral

retina is increased; though the process of dark

adaptation itself is not affected until very late.

3. Tubular vision occurs in advanced cases.

(B) Fundus changes (Fig. 11.18)

1. Retinal pigmentary changes. These are typically

perivascular and resemble bone corpuscles in

shape. Initially, these changes are found in the

equatorial region only and later spread both

anteriorly and posteriorly.

Fig. 11.19. Consecutive optic atrophy in retinitis pigmentosa.

DISEASES OF THE RETINA

269

4. Usher’s syndrome. It includes retinitis pigmentosa

and labyrinthine deafness.

5. Hallgren’s syndrome. It comprises retinitis

pigmentosa, vestibulo-cerebellar ataxia, congenital

deafness and mental deficiency.

Atypical forms of retinitis pigmentosa

1. Retinitis pigmentosa sine pigmento. It is

characterised by all the clinical features of typical

retinitis pigmentosa, except that there are no

visible pigmentary changes in the fundus.

2. Sectorial retinitis pigmentosa. It is characterised

by involvement of only one sector of the retina.

3. Pericentric retinitis pigmentosa. In this condition

all the clinical features are similar to typical retinitis

pigmentosa except that pigmentary changes are

confined to an area, immediately around the

macula.

4. Retinitis punctata albescens. It is characterised

Fig. 11.20. Field changes in retinitis pigmentosa.

by the presence of innumerable discrete white

dots scattered over the fundus without pigmentary

only central vision is left (tubular vision). Eventually

changes. Other features are narrowing of

even this is also lost and the patient becomes blind.

arterioles, night blindness and constriction of

visual fields.

(D) Electrophysiological changes

Typical electrophysiological changes appear early in

Treatment

the disease before the subjective symptoms or the

It is most unsatisfactory; rather we can say that till

date there is no effective treatment for the disease.

objective signs (fundus changes) appear.

1. Measures to stop progression, which have been

1. Electro-retinogram

(ERG) is subnormal or

tried from time to time, without any breakthrough

abolished.

include: vasodilators, placental extracts,

2. Electro-oculogram (EOG) shows absence of light

transplantation of rectus muscles into

peak.

suprachoroidal space, light exclusion therapy,

Associations of retinitis pigmentosa

ultrasonic therapy and acupuncture therapy.

Recently vitamin A and E have been

I. Ocular associations. These include myopia, primary

recommended to check its progression.

open angle glaucoma, microphthalmos, conical cornea

2. Low vision aids (LVA) in the form of ‘magnifying

and posterior subcapsular cataract.

glasses’ and

‘night vision device’ may be of

II. Systemic associations. These are in the form of

some help.

following syndromes:

3. Rehabilitation of the patient should be carried

1. Laurence-Moon-Biedl syndrome. It is

out as per his socio-economic background.

characterised by retinitis pigmentosa, obesity,

4. Prophylaxis. Genetic counselling for no

hypogenitalism, polydactyly and mental

consanguinous marriages may help to reduce the

deficiency.

incidence of disease. Further, affected individuals

2. Cockayne’s syndrome. It comprises retinitis

should be advised not to produce children.

pigmentosa, progressive infantile deafness,

dwarfism, mental retardation, nystagmus and

PERIPHERAL RETINAL DEGENERATIONS

ataxia.

3. Refsum’s syndrome. It is characterised by retinitis

1. Lattice degeneration. It is the most important

pigmentosa, peripheral neuropathy and cerebellar

degeneration associated with retinal detachment. Its

ataxia.

incidence is 6 to 10% in general population and 15 to

270

Comprehensive OPHTHALMOLOGY

20% in myopic patients. It is characterised by white

4. White-with-pressure and white-without pressure.

arborizing lines arranged in a lattice pattern along

These are not uncommonly associated with retinal

with areas of retinal thinning and abnormal

detachment. ‘White-with-pressure’ lesions are

pigmentation (Fig. 11.21A). Small round retinal holes

characterised by greyish translucent appearance of

are frequently present in it. The typical lesion is

retina seen on scleral indentation. ‘White-without-

spindle-shaped, located between the ora serrata and

pressure’ lesions are located in the peripheral retina

the equator with its long axis being circumferentially

and may be associated with lattice degeneration.

oriented. It more frequently involves the temporal than

5. Focal pigment clumps. These are small, localised

the nasal, and superior than the inferior halves of the

areas of irregular pigmentation, usually seen in the

fundus.

equatorial region. These may be associated with

2. Snail tract degeneration. It is a variant of lattice

posterior vitreous detachment and/or retinal tear.

degeneration in which white lines are replaced by

6. Diffuse chorioretinal degeneration. It is

snow-flake areas which give the retina a white frost-

characterised by diffuse areas of retinal thinning and

like appearance (Fig. 11.21B).

depigmentation of underlying choroid. It commonly

3. Acquired retinoschisis. The term retinoschisis

involves equatorial region of highly myopic eyes.

refers to splitting of the sensory retina into two layers

7. Peripheral cystoid retinal degeneration. It is a

at the level of the inner nuclear and outer plexiform

common degeneration seen in the eyes of old people.

layers. It occurs in two forms — the congenital and

It may predispose to retinal detachment in some very

acquired. The latter, also called as senile retinoschisis,

old people.

may rarely act as predisposing factor for primary retinal

detachment.

VITREORETINAL DEGENERATIONS

Acquired retinoschisis is characterised by thin,

Vitreoretinal degenerations or vitreoretinopathies

transparent, immobile, shallow elevation of the inner

include:

retinal layers which typically produces absolute field

Wagner’s syndrome,

defects—the fact which helps in differentiating it from

Stickler syndrome,

the shallow retinal detachment which produces a

Favre-Goldmann syndrome,

relative scotoma. The condition is frequently bilateral

Familial exudative vitreoretinopathy,

and usually involves the lower temporal quadrants,

Erosive vitreoretinopathy,

anterior to the equator.

Dominant neovascular inflammatory vitreoretino-

pathy

Dominant vitreoretinochoroidopathy.

Note : Characterstic features of some conditions are

mentioned here.

Wagner’s syndrome

Wagner’s syndrome has an autosomal dominant (AD)

inheretance with following features:

Vitreous is liquified with condensed membranes.

Retina shows narrow and sheathed vessels, and

pigmented spots in the periphery.

Choroid may be atrophied.

Cataract may develop as late complication.

Stickler syndrome

Fig. 11.21. Peripheral retinal degernerations : A, Lattice

Stickler syndrome, also known as hereditary arthro-

degeneration, B,Snail track degeneration : C, Acquired

ophthalmopathy, is an autosomal dominant

retinoschisis ; D, white-with-pressure; E, Focal pigment

connective tissue disorder characterized by following

clumps; F, Diffuse chorioretinal degeneration; and

G, Peripheral cystoid degeneration.

features:

DISEASES OF THE RETINA

271

Ocular features

C. Acquired maculopathies include:

Vitreous is liquified and shows syneresis giving

1. Traumatic lesions. These include macular oedema,

appearance of an optically-empty vitreous cavity.

traumatic macular degeneration, macular haemorr-

hage and macular hole (see page 406).

Progressive myopia is very common

2. Inflammations. These are: central chorioretinitis

Radial lattice like degeneration associated with

pigmentary changes and vascular sheathing.

(see page 149) and photoretinitis (sunburn).

3. Degenerations. Important conditions are age

Bilateral retinal detachment may occur in 30%

related macular degeneration

(ARMD), and

cases

(commonest inherited cause of retinal

myopic degeneration.

detachment in children)

4. Metabolic disorders. These include: diabetic

Ectopia lentis is occasionally associated.

maculopathy and sphingolipidosis.

Pre-senile cataract occurs in 50% cases.

5. Toxic maculopathies. These are chloroquine and

Orofacial abnormalities include flattered nasal

phenothiazine-induced maculopathy.

bridge, maxillary hypoplasia, cleft palate and high

6. Miscellaneous acquired maculopathies. A few

arched palate.

common conditions are: central serous retinopathy

Arthropathy is characterized by stiff, painful,

(CSR), cystoid macular oedema (CME), macular

prominent and hyperextensible large joints.

hole, and macular pucker.

Other features include deafness and mitral valve

Only a few important macular lesions are described

prolapse.

here.

Favre-Goldmann syndrome

It is an autosomal recessive condition presenting in

PHOTORETINITIS

childhood with nyctalopia. Characterstic features are:

Photoretinitis, also known as solar retinopathy or

Vitreous shows syneresis but the cavity is not

eclipse retinopathy, refers to retinal injury induced

optically empty.

by direct or indirect sun viewing. Solar retinopathy is

Retinoschisis, both central (affecting macula) and

associated with religious sun gazing, solar eclipse

peripheral, is present, although macular findings

observing, telescopic solar viewing, sun bathing and

are more subtle.

sun watching in psychiatric disorders.

Pigmentary changes similar to retinitis pigmentosa

Causes of photic retinopathy, other than solar

are marked

retinopathy, are:

ERG is subnormal.

Welding arc exposure,

Lightening retinopathy and

Retinal phototoxicity from ophthalmic instruments

MACULAR DISORDERS

like operating microscope.

Pathogenesis

Macula, being concerned with vision, has attracted

the attention of many retina specialists.

Solar radiations damage the retina through:

Consequently, many disorders have been defined and

Photochemical effects produced by UV and visible

variously classified. A simple, etiological

blue light, and

classification for a broad overview of the macular

Thermal effects may enhance the photochemical

lesions is as follows:

effects. The long visible wave length and infra-

A. Congenital anomalies. These include aplasia,

red rays from the sun are absorbed by the pigment

hypoplasia and coloboma.

epithelium producing a thermal effect. Therefore,

B. Hereditary dystrophies. These include Best’s

severity of lesion varies directly with the degree

disease, Stargardt’s disease, butterfly-shaped

of pigmentation of the fundus, duration of

dystrophy, bull’s eye dystrophy and central areolar

exposure and the climatic conditions during

dystrophy.

exposure.

272

Comprehensive OPHTHALMOLOGY

Clinical features

patients with CSR. Factors reported to induce or

Symptoms. These include persistence of negative

aggravate CSR include: emotional stress,

after-image of the sun, progressing later into a

hypertension, and administration of systemic steroids.

positive scotoma and metamorphopsia. Unilateral or

Clinical features

bilateral deceased vision (6/12-6/60) which develops

Symptoms. Patient presents with a sudden onset of

within 1 to 4 hours after solar exposure, usually

painless loss of vision (6/9-6/24) associated with

improves to 6/6 -6/12 within six months.

relative positive scotoma, micropsia and

Signs. Initially the fundus may appear normal. Shortly

metamorphopsia.

after exposure a small yellow spot with gray margin

Ophthalmoscopic examination reveals, mild

may be noted in the foveolar and parafoveolar region.

elevation of macular area, demarcated by a circular

The typical lesion, which appears later, consists of a

ring-reflex. Foveal reflex is absent or distorted

central burnt-out hole in the pigment epithelium

(Fig. 11.22).

surrounded by aggregation of mottled pigment.

CSR is usually self-limiting but often recurrent.

Ophthalmoscopically, it appears as a bean-or kidney-

Resolution may take three weeks to one year

shaped pigmented spot with yellowish white centre

and often leaves behind small areas of atrophy

in the foveal region. In worst cases, typical macular

hole may appear.

and pigmentary disturbances.

Fundus fluorescein angiography helps in confirming

Treatment

the diagnosis. Two patterns are seen:

There is no effective treatment for photoretinitis, so

Ink-blot pattern. It consists of small hyperflu-

emphasis should be on prevention. Eclipse viewing

orescent spot which gradually increases in size

should be discouragde unless there is proper use of

(Fig. 11.23A).

protective eye wear filters (which absorb UV and

Smoke-stack pattern. It consists of a small

infrared wave lengths).

hyperfluorescent spot which ascends vertically

Prognosis is guarded, since some scotoma and loss

like a smoke-stack and gradually spreads laterally

in visual acuity by one or two lines mostly persists.

to take a mushroom or umbrella configuration

(Fig. 11.23B).

CENTRAL SEROUS RETINOPATHY (CSR)

Central serous retinopathy (CSR) is characterised by

spontaneous serous detachment of neurosensory

retina in the macular region, with or without retinal

pigment epithelium detachment. Presently it is termed

as idiopathic central serous choroidopathy (ICSC).

Etispathogenesis

It is not known exactly. The condition typically affects

males between 20 and 40 years of age. It is now

believed that an increase in choroidal

hyperpermeability causes a breach in the outer blood

retinal barrier (a small opening or blow out of RPE).

Leakage of fluid across this area results in

development of localized serous detachment of

neurosensory retina. What triggers the choroidal

hyperpermeability is poorly understood. It is being

suggested that an imbalance between the sympathetic

parasympathetic drive that maintains autoregulation

Fig. 11.22. Fundus photograph showing central

within the choroidal vasculature may be defective in

serous retinopathy.

DISEASES OF THE RETINA

273

Fig.

11.23. Fundus fluorescein angiogram showing ink-blot pattern (A) and smoke-stack pattern (B) of

hyperfluorescence in central serous retinopathy.

Treatment

4. As a side-effect of drugs e.g., following use of

1. Reassurance is the only treatment required in

adrenaline eyedrops, especially for aphakic

glaucoma.

majority of the cases, since CSR undergoes

5. Retinal dystrophies e.g., retinitis pigmentosa.

spontaneous resolution in 80 to 90 percent cases.

Visual acuity returns to normal or near normal

Pathogenesis

within 4 to 12 weeks.

CME develops due to leakage of fluid following

2. Laser photocoagulation is indicated in following

breakdown of inner blood-retinal barrier (i.e., leakage

cases:

from the retinal capillaries).

Long-standing cases

(more than 4 months)

Clinical features

with marked loss of vision.

1. Visual loss. Initially there is minimal to moderate

Patients having recurrent CSR with visual loss.

loss of vision, unassociated with other symptoms.

Patients having permanent loss of vision in

If oedema persists, there may occur permanent

the other eye due to this condition.

decrease in vision.

2. Ophthalmoscopy in clinically established cases

CYSTOID MACULAR EDEMA (CME)

reveals a typical ‘Honey-comb appearance’ of

macula (due to multiple cystoid oval spaces) (Fig.

It refers to collection of fluid in the outer plexiform

(Henle’s layer) and inner nuclear layer of the retina,

11.24). CME is best examined with a fundus

contact lens on slit-lamp or +90D lens.

centred around the foveola.

3. Fundus fluorescein angiography demonstrates

Etiology

leakage and accumulation of dye in the macular

It is associated with a number of disorders. A few

region which in a well-established case presents

common causes are as follows:

a ‘flower petal appearance’ (Fig. 11.25).

1. As postoperative complication following cataract

Complications

extraction and penetrating keratoplasty.

Long-standing CME may end in lamellar macular hole.

2. Retinal vascular disorders e.g., diabetic

Treatment

retinopathy and central retinal vein occlusion.

1. Treatment of the causative factor, e.g.,

3. Intraocular inflammations e.g., pars planitis,

photocoagulation for diabetic CSME; cessation of

posterior uveitis, Behcet disease.

causative topical 2% adrenaline eye drops, so on.

274

Comprehensive OPHTHALMOLOGY

in population above the age of 65 years. It is of two

types non-exudative and exudative.

Etiopathogenesis

ARMD is an age-related disease of worldwide

prevalence. Certain risk factors which may affect the

age of onset and/or progression include heredity,

nutrition, smoking, hypertension and exposure to sun

light. The disease is most prevalent in caucasians.

Clinical types

1. Non-exudative or atrophic ARMD. It is also called

Fig. 11.24. Fundus photograph showing honey-comb

dry or geographic ARMD and is responsible for 90

appearance in cystoid macular edema (CME).

percent cases. It typically causes mild to moderate,

gradual loss of vision. Patients may complain of

distorted vision, difficulty in reading due to central

shadowing. Ophthalmoscopically (Fig. 11.26A), it is

characterised by occurrence of drusens (colloid

bodies), pale areas of retinal pigment epithelium

atrophy and irregular or clustered pigmentation.

Drusens appear as small discrete, yellowish-white,

slightly elevated spots. In later stages, there occurs

enlargement of the atrophic areas within which the

larger choroidal vessels may become visible

(geographic atrophy).

2. Exudative ARMD. It is also called wet or

neovascular ARMD. It is responsible for only 10

percent cases of ARMD but is associated with

comparatively rapidly progressive marked loss of

vision. Typically, the course of exudative ARMD

rapidly passes through many stages. These include:

Fig. 11.25. Fundus fluorescein angiogram showing

Stage of drusen formation,

flower petal appearance in a patient with cystoid

Stage of retinal pigment epithelium

(RPE)

macular edema.

detachment,

Topical antiprostaglandin drops like

Stage of choroidal neovascularisation (CNV) (Fig.

indomethacin or flurbiprofen, used pre and post-

11.26B),

operatively, prevent the occurrence of CME

Stage of haemorrhagic detachment of RPE,

associated with intraocular surgery.

Stage of haemorrhagic detachment of

neurosensory retina, and

Topical and systemic steroids may be of some

Stage of disciform (scarring) macular degeneration.

use in established cases.

Systemic carbonic anhydrase inhibitors (CAIs)

Early versus late ARMD

e.g., oral acetazolamide may be beneficial is some

Eary ARMD includes drusens, and areas of RPE

cases of CME.

hyperpigmentation and/or depigmentation.

Late ARMD includes geographic atrophy of RPE with

AGE-RELATED MACULAR DEGENERATION

visible underlying choroidal vessels, pigment

Age-related macular degeneration (ARMD), also

epithelium detachment (PED) with or without

called senile macular degeneration, is a bilateral

neurosensory retinal detachment, subretinal or sub-

disease of persons of 59 years of age or older. It is a

RPE neovascularization, haemorrhage and disciform

leading cause of blindness in developed countries,

scars.

DISEASES OF THE RETINA

275

Role of dietary supplements and antioxidants in

prevention or treatment of ARMD. The age-related

eye disease study (AREDS) has suggested that use

of certain specific antioxidants, vitamins and minerals

(vitamin C and E, beta carotene, zinc and copper) could

possibly prevent or delay the progression of ARMD.

Treatment modalities available to treat exudative

(neovascular) ARMD are:

Argon green-laser photocoagulation is the

treatment of choice for extrafoveal choroidal

neovascular membrane (CNVM).

Photodynamic therapy (PDT) is the treatment of

choice for subfoveal and juxtafoveal classic

CNVM. In PDT, vertiporfin, a photosensitizer or

light activated dye is injected intravenously. The

area of CNVM is then exposed to light from a

diode laser source at a wavelength (689 nm) that

corresponds to absorption peak of the dye. The

light-activated dye then causes disruption of

cellular structures and occlusion of CNVM with

minimum damage to adjacent RPE, photoreceptors

and capillaries.

Transpupillary thermotherapy (TTT) with a diode

laser (810 nm) may be considered for subfoveal

occult CNVM. PDT is definitely better than TTT

but is very costly.

Surgical treatment in the form of submacular

surgery to remove CNVM and macular

translocation surgery are being evaluated.

Pharmacologic modulation with antiangiogenic

agent like interferon alfa-29, and inhibitor of

Fig. 11.26. Age-related macular degeneration: A,

vascular endothelial growth factor (VEGF) is under

nonexudative; B, exudative.

experimental trial.

Diagnosis

RETINAL DETACHMENT

Clinical diagnosis is made from the typical signs

described above, which are best elucidated on

It is the separation of neurosensory retina proper

examination of the macula by slit-lamp biomicroscopy

from the pigment epithelium. Normally these two

with a +90D/+78D non-contact lens or Mainster

layers are loosely attached to each other with a

contact lens.

potential space in between. Hence, actually speaking

Fundus fluorescein angiography and indocyanine

the term retinal detachment is a misnomer and it

green angiography help in detecting choroidal

should be retinal separation.

neovascularization (CNV) in relation to foveal

Classification

avascular zone. Which may be subfoveal, juxta foveal

or extrafoveal CNV may be classical or occult.

Clinico-etiologically retinal detachment can be

classified into three types:

Treatment

1. Rhegmatogenous or primary retinal detachment.

There is no effective treatment for non-exudative

2. Tractional retinal detachment

Secondary

ARMD. However, some treatment options are

retinal

available for exudative ARMD.

3. Exudative retinal detachment

detachment

276

Comprehensive OPHTHALMOLOGY

RHEGMATOGENOUS OR PRIMARY RETINAL

Senile acute

Predisposing

Aphakia

DETACHMENT

posterior

retinal

(Endodonesis)

vitreous

degenerations

It is usually associated with a retinal break (hole or

detachment

tear) through which subretinal fluid (SRF) seeps and

(acute PVD)

separates the sensory retina from the pigmentary

↓

epithelium.

Retinal break

←

Trauma

↓

Etiology

The degenerated fluid vitreous seeps through the retinal

break and collects as subretinal fluid (SRF) between

It is still not clear exactly. The predisposing factors

the sensory retina and pigmentary epithelium.

and the proposed pathogenesis is as follows:

↓

Retinal detachment

A. Predisposing factors include:

1. Age. The condition is most common in 40-60

Fig. 11.27. Flow chart depicting pathogenesis of

years. However, age is no bar.

rhegmatogenous retinal detachment.

2. Sex. More common in males (M:F—3:2).

3. Myopia. About 40 percent cases of rhegmato-

Clinical features

genous retinal detachment are myopic.

Prodromal symptoms. These include dark spots

4. Aphakia. The condition is more common in

(floaters) in front of the eye (due to rapid vitreous

aphakes than phakes.

degeneration) and photopsia, i.e., sensation of flashes

5. Retinal degenerations predisposed to retinal

of light (due to irritation of retina by vitreous

detachment are as follows:

movements).

Lattice degeneration

Symptoms of detached retina. These are as follows:

Snail track degeneration.

1. Localised relative loss in the field of vision (of

White-with-pressure and white-without-or

detached retina) is noticed by the patient in early

occult pressure.

stage which progresses to a total loss when

Acquired retinoschisis.

peripheral detachment proceeds gradually towards

Focal pigment clumps.

the macular area.

6. Trauma. It may also act as a predisposing factor.

2. Sudden painless loss of vision occurs when the

7. Senile posterior vitreous detachment (PVD). It

detachment is large and central. Such patients

is associated with retinal detachment in many

usually complain of sudden appearance of a dark

cases.

cloud or veil in front of the eye.

B. Pathogenesis

Signs. These are elicited on following examinations:

1. External examination, eye is usually normal.

Pathogenesis of rhegmatogenous retinal detachment

2. Intraocular pressure is usually slightly lower or

(RRD) is summarized in Figure 11.27. The retinal

may be normal.

breaks responsible for RRD are caused by the interplay

3. Marcus Gunn pupil (relative afferent pupillary

between the dynamic vitreoretinal traction and

defect) is present in eyes with extensive RD.

predisposing degeneration in the peripheral retina.

4. Plane mirror examination reveals an altered red

Dynamic vitreoretinal traction is induced by rapid eye

reflex in pupillary area (i.e., greyish reflex in the

movements especially in the presence of PVD,

quadrant of detached retina).

vitreous synersis, aphakia and myopia. Once the

5. Ophthalmoscopy should be carried out both by

retinal break is formed, the liquified vitreous may seep

direct and indirect techniques. Retinal detachment

through it separating the sensory retina from the

is best examined by indirect ophthalmoscopy

pigment epithelium. As the subretinal fluid (SRF)

using scleral indentation (to enhance visualization

accumulates, it tends to gravitate downwards. The

of the peripheral retina anterior to equator). On

final shape and position of RD is determined by

examination, freshly-detached retina gives grey

location of retinal break, and the anatomical limits of

reflex instead of normal pink reflex and is raised

optic disc and ora serrata.

anteriorly

(convex configuration). It is thrown

DISEASES OF THE RETINA

277

into folds which oscillate with the movements of

Complications

the eye. These may be small or may assume the

These usually occur in long-standing cases and

shape of balloons in large bullous retinal

include proliferative vitreoretinopathy (PVR),

detachment. In total detachment retina becomes

complicated cataract, uveitis and phthisis bulbi.

funnel-shaped, being attached only at the disc

and ora serrata. Retinal vessels appear as dark

Treatment

tortuous cords oscillating with the movement of

Basic principles and steps of RD surgery are:

detached retina. Retinal breaks associated with

1. Sealing of retinal breaks. All the retinal breaks

rhegmatogenous detachment are located with

should be detected, accurately localised and sealed

difficulty. These look reddish in colour and vary

by producing aseptic chorioretinitis, with

in shape. These may be round, horse-shoe

cryocoagulation, or photocoagulation or diathermy.

shaped, slit-like or in the form of a large anterior

Cryocoagulation is more frequently utilised (Fig.

dialysis

(Fig.

11.28). Retinal breaks are most

11.29).

frequently found in the periphery (commonest in

2. SRF drainage. It allows immediate apposition

the upper temporal quadrant). Associated retinal

between sensory retina and RPE. SRF drainage is done

degenerations, pigmentation and haemorrhages

very carefully by inserting a fine needle through the

may be discovered.

sclera and choroid into the subretinal space and

Old retinal detachment is characterized by

allowing SRF to drain away. SRF drainage may not be

retinal thining

(due to atrophy), formation of

required in some cases.

subretinal demarcation line (high water markes)

due to proliferation of RPE cells at the junction

3. To maintain chorioretinal apposition for at least

of flat detachment and formation of secondary

a couple of weeks. This can be accomplished by either

intraretinal cysts (in very old RD).

of the following procedures depending upon the

clinical condition of the eye:

Visual field charting reveals scotomas

i. Scleral buckling i.e., inward indentation of sclera

corresponding to the area of detached retina,

to provide external temponade is still widely

which are relative to begin with but become

used to achieve the above mentioned goal

absolute in long-standing cases.

successfully in simple cases of primary RD. Scleral

Electroretinography

(ERG) is subnormal or

buckling is achieved by inserting an explant

absent.

(silicone sponge or solid silicone band) with the

Ultrasonography confirms the diagnosis. It is of

help of mattress type sutures applied in the

particular value in patients with hazy media

sclera (Fig. 11.30). Radially oriented explant is

especially in the presence of dense cataracts.

most effective in sealing an isolated hole, and

Fig. 11.28. Retinal detachment associated with: A, horse-shoe tear; B, round retinal hole; C, anterior dialysis.

278

Comprehensive OPHTHALMOLOGY

circumferential explant (encirclage) is indicated in

iii. Parsplana vitrectomy, endolaser photocoagu-

breaks involving three or more quadrants.

lation and internal temponade. This procedure

ii.

Pneumatic retinopaxy is a simple outpatient

is indicated in:

procedure which can be used to fix a fresh

All complicated primary RDs, and

superior RD with one or two small holes extending

All tractional RDs.

over less than two clock hours in upper two

thirds of the peripheral retina. In this technique

Presently, even in uncomplicated primary RDs

after sealing the breaks with cryopaxy, an

(where scleral buckling is successful), the

expanding gas bubble (SF₆ or C₃F₈) is injected in

primary vitrectomy is being used with increased

the vitreous. Then proper postioning of the

frequency by the experts in a bid to provide

patient is done so that the break is uppermost

better resutls.

and the gas bubble remains in contact with the

Main steps of this procedure are:

tear for 5-7 days.

Pars plana,3-port vitrectomy (see page 247) is

done to remove all membranes and vitreous

and to clean the edges of retinal breaks.

Internal drainage of SRF through existing

retinal breaks using a fine needle or through a

posterior retinotomy is done.

Flattening of the retina is done by injecting

silicone oil or perflurocarbon liquid.

Endolaser is then applied around the area of

retinal tears and holes to create chorioretinal

adhesions.

To temponade the retina internally either

silicone oil is left inside or is exchanged with

some long acting gas (air-silicone oil exchange).

Gases commonly used to temponade the retina

Fig. 11.29. Cryocoagulation of the retinal hole area under

are sulphur hexafluoride

(SF₆) or

direct vision with indirect ophthalmoscopy.

perfluoropropane (C₃F₈) (see page 247).

Prophylaxis

Occurrence of primary retinal detachment can be

prevented by timely application of laser

photocoagulation or cryotherapy in the areas of

retinal breaks and/or predisposing lesions like lattice

degeneration. Prophylactic measures are particularly

indicated in patients having associated high risk

factors like myopia, aphakia, retinal detachment in

the fellow eye or history of retinal detachment in the

family.

EXUDATIVE OR SOLID RETINAL DETACHMENT

It occurs due to the retina being pushed away by a

neoplasm or accumulation of fluid beneath the retina

Fig. 11.30. Diagram depicting scleral buckling and sub-

retinal fluid (SRF) drainage.

following inflammatory or vascular lesions.

DISEASES OF THE RETINA

279

Etiology

Treatment

Its common causes can be grouped as under:

Exudative retinal detachment due to transudate,

1. Systemic diseases. These include: toxaemia of

exudate and haemorrhage may undergo

pregnancy, renal hypertension, blood dyscrasias

spontaneous regression following absorption of

and polyarteritis nodosa.

the fluid. Thus, the treatment should be for the

2. Ocular diseases. These include: (i) Inflammations

causative disease.

such as Harada’s disease, sympathetic ophthalmia,

Presence of intraocular tumours usually requires

posterior scleritis, and orbital cellulitis; (ii) Vascular

enucleation.

diseases such as central serous retinopathy and

exudative retinopathy of Coats; (iii) Neoplasms

TRACTIONAL RETINAL DETACHMENT

e.g., malignant melanoma of choroid and

It occurs due to retina being mechanically pulled

retinoblastoma

(exophytic type);

(iv) Sudden

away from its bed by the contraction of fibrous tissue

hypotony due to perforation of globe and

in the vitreous (vitreoretinal tractional bands).

intraocular operations.

Etiology

Clinical features

It is associated with the following conditions:

Exudative retinal detachment can be differentiated

Post-traumatic retraction of scar tissue especially

from a simple primary detachment by:

following penetrating injury.

Absence of photopsia, holes/tears, folds and

Proliferative diabetic retinopathy.

undulations.

Post-haemorrhagic retinitis proliferans.

The exudative detachment is smooth and convex

Retinopathy of prematurity.

(Fig.

11.31). At the summit of a tumour it is

Plastic cyclitis.

usually rounded and fixed and may show

Sickle cell retinopathy.

pigmentary disturbances.

Proliferative retinopathy in Eales’ disease.

Occasionally, pattern of retinal vessels may be

Clinical features

disturbed due to presence of neovascularisation

on the tumour summit.

Tractional retinal detachment

(Fig.

11.32) is

Shifting fluid characterised by changing position

charcterised by presence of vitreoretinal bands

of the detached area with gravity is the hallmark

with lesions of the causative disease.

of exudative retinal detachment.

Retinal breaks are usually absent and

On transillumination test a simple detachment

configuration of the detached area is concave.

appears transparent while solid detachment is

The highest elevation of the retina occurs at sites

opaque.

of vitreoretinal traction.

Retinal mobility is severely reduced and shifting

fluid is absent.

Treatment

It is difficult and requires pars plana vitrectomy to

cut the vitreoretinal tractional bands and internal

tamponade as described above. Prognosis in such

cases is usually not so good.

TUMOURS OF RETINA

Tumours of retina have become a subject of increasing

interest to clinical ophthalmologists as well as ocular

pathologists. Their classification is given here and

Fig. 11.31. Exudative retinal detachment in a patient with

malignant melanoma of choroid.

only a few of common interests are described.

280

Comprehensive OPHTHALMOLOGY

4. Race. It is rarer in Negroes than Whites.

5. Bilaterality. In

25-30 percent cases, there is

bilateral involvement, although one eye is affected

more extensively and earlier than the other.

Genetics and heredity

Retinoblastoma (RB) gene has been identified as 14

band on the long-arm of chromosome 13 (13q 14) and

is a ‘cancer suppressor’ or ‘antioncogenic’ gene.

Deletion or inactivation of this protective gene by

two mutations (Knudson’s two hit hypothesis) results

in occurrence of retinoblastoma.

Retinoblastoma may arise as hereditary and non-

Fig. 11.32. Tractional retinal detachment in a patient with

herditary forms.

advanced diabetic retinopathy.

1. Hereditary or familial cases. In such cases first

hit (mutation) occurs in one of the parental germ cells

Classification

before fertilization. This means mutation will occur in

A. Primary tumours

all somatic cells (predisposing to develop even non-

1. Neuroblastic tumours. These arise from sensory

ocular tumour). Second hit (mutation) occurs late in

retina

(retinoblastoma and astrocytoma) and

postzygote phase and affects the second allele,

pigment epithelium

(benign epithelioma and

resulting in development of retinoblastoma. Some

melanotic malignant tumours).

facts about hereditary retinoblastoma are:

2. Mesodermal angiomata e.g., cavernous

Accounts for 40% of all cases.

haemangioma.

All bilateral cases and about 15% of the unilateral

3. Phakomatoses. These include: angiomatosis

cases are hereditary.

retinae

(von Hippel-Lindau disease), tuberous

Most hereditary cases are multifocal.

sclerosis

(Bourneville’s disease), neuro-

Some hereditary cases have trilateral retinoblas-

fibromatosis (von Recklinghausen’s disease and

toma (i.e., have associated pinealoblastoma).

encephalo-trigeminal angiomatosis (Sturge-Weber

syndrome).

Inheritance is autosomal dominant and the risk of

transmitting the gene mutation is 50%. Because

B. Secondary tumours

of high peneterance 40% of offspring of a surviver

1. Direct extension e.g., from malignant melanoma

of heraditary retinoblastoma will develop the

of the choroid.

tumour.

2. Metastatic carcinomas from the gastrointestinal

There are 40% chances of developing tumour in

tract, genitourinary tract, lungs, and pancreas.

a sibling of a child with bilateral retinoblastoma

3. Metastatic sarcomas.

(with unaffected parents).

4. Metastatic malignant melanoma from the skin.

2. Non-hereditary or sporadic cases. In non-

RETINOBLASTOMA

hereditary cases both hits (mutations) occur in the

embryo after fertilization and in the same retinal cell.

It is a common congenital malignant tumour arising

Some facts about non-hereditary

(somatic)

from the neurosensory retina in one or both eyes.

retinoblastoma are:

Incidence

Accounts for 60% of all cases.

1. It is the most common intraocular tumour of

All non-hereditary cases are unilateral and

childhood occurring 1 in 20,000 live births.

unifocal and accounts for 85% of the all unilateral

2. Age. Though congenital, it is not recognised at

cases of retinoblastoma.

birth, and is usually seen between 1 and 2 years

Patient is not predisposed to get second non-

of age.

ocular cancer.

3. Sex. There is no sex predisposition.

Tumour is not transmissible.

DISEASES OF THE RETINA

281

Pathology

4. Defective vision. Very rarely, when the tumour

Origin. It arises as malignant proliferation of the

arises late

(3-5 years of age), the child may

complain of defective vision.

immature retinal neural cells called, retinoblasts,

5. Ophthalmoscopic features of tumour. In the early

which have lost both antioncogenic genes.

stages, before the appearance of leukocoria,

Histopathology. Growth chiefly consists of small

fundus examination after full mydriasis may reveal

round cells with large nuclei, resembling the cells of

the growth. Ophthalmoscopic signs in two types

the nuclear layer of retina. These cells may present

of retinoblastoma are as follows:

as a highly undifferentiated or well-differentiated

i. Endophytic retinoblastoma (Fig. 11.35A): It

tumour. Microscopic features of a well differentiated

grows inwards from the retina into the

tumour include Flexner-Wintersteiner rosettes,

vitreous cavity. On ophthalmoscopic

(highly specific of retinoblastoma), Homer-Wright

examination, the tumour looks like a well

rosettes, pseudorosettes and fleurettes formation

circumscribed polypoidal mass of white or

(Fig. 11.33). Other histologic features are presence of

pearly pink in colour. Fine blood vessels and

areas of necrosis and calcification.

sometimes a haemorrhage may be present on

its surface. In the presence of calcification, it

Clinical picture

gives the typical ‘cottage cheese’ appearance.

It may be divided into four stages:

There may be multiple growths projecting

I. Quiescent stage. It lasts for about 6 months to one

into the vitreous.

year. During this stage, child may have any of the

ii. Exophytic retinoblastoma (Fig. 11.35B). It

following features:

grows outwards and separates the retina

1. Leukocoria or yellowish-white pupillary reflex

from the choroid. On fundus examination it

(also called as amaurotic cat’s eye appearance)

gives appearance of exudative retinal

is the commonest feature noticed in this stage

detachment (see page 278).

(Fig. 11.34).

II. Glaucomatous stage. It develops when

2. Squint, usually convergent, may develop in some

retinoblastoma is left untreated during the quiescent

cases.

stage. This stage is characterised by severe pain,

3. Nystagmus is a rare feature, noticed in bilateral

redness, and watering.

cases.

Signs. Eyeball is enlarged with apparent proptosis,

conjunctiva is congested, cornea become hazy,

intraocular pressure is raised. Occasionally, picture

simulating severe, acute uveitis usually associated

with pseudohypopyon and/or hyphaema may be the

presenting mode (retinoblastoma masquerading as

iridocyclitis).

Fig. 11.34. Leukocoria right eye in a patient

Fig. 11.33. Histopathological picture of retinoblastoma.

with retinoblastoma.

282

Comprehensive OPHTHALMOLOGY

Fig. 11.36. Fungating retinoblastoma involving the orbit.

as leukocoria are collectively called as

‘pseudoglioma'. A few common conditions are

congenital cataract, inflammatory deposits in vitreous

following a plastic cyclitis or choroiditis, coloboma

of the choroid, the retrolental fibroplasia (retinopathy

of prematurity), persistent hyperplastic primary

vitreous, toxocara endophthalmitis and exudative

retinopathy of Coats.

Fig. 11.35. Drawing of the cross-section of the

2. Endophytic retinoblastoma discovered on fundus

eyeball showing: A, endophytic retinoblastoma;

B, exophytic retinoblastoma.

examination should be differentiated from retinal

tumours in tuberous sclerosis and neurofibromatosis,

III. Stage of extraocular extension. Due to

astrocytoma and a patch of exudative choroiditis.

progressive enlargement, of tumour the globe bursts

3. Exophytic retinoblastoma should be differentiated

through the sclera, usually near the limbus or near

from other causes of exudative retinal detachment

the optic disc. It is followed by rapid fungation and

(see page 278).

involvement of extraocular tissues resulting in marked

proptosis (Fig. 11.36).

Diagnosis

IV. Stage of distant metastasis. It is characterised by

1. Examination under anaesthesia: It should be

the involvement of distant structures as follows:

1. Lymphatic spread first occurs in the preauricular

performed in all clinically suspected cases. It

and neighbouring lymph nodes.

should include fundus examination of both eyes

2. Direct extension by continuity to the optic nerve

after full mydriasis with atropine (direct as well as

and brain is common.

indirect ophthalmoscopy), measurement of

3. Metastasis by blood stream involves cranial and

intraocular pressure and corneal diameter.

other bones. Metastasis in other organs, usually

2. Plain X-rays of orbit may show calcification

the liver, is relatively rare.

which occurs in

75 percent cases of

Differential diagnosis

retinoblastoma.

1. Differential diagnosis of leukocoria. Various

3. Lactic dehydrogenase (LDH) level is raised in

conditions other than retinoblastoma, which present

aqueous humour.

DISEASES OF THE RETINA

283

4. Ultrasonography and CT scanning are very

However, if the above modalities are not available,

useful in the diagnosis. CT also demonstrates

the eyeball should be enucleated without hesitation.

extension to optic nerve, orbit and CNS, if any

2. Enucleation. It is the treatment of choice when:

(Fig. 11.37).

Tumour involves more than half of the retina.

Treatment

Optic nerve is involved.

1. Tumour destructive therapy. When tumour is

Glaucoma is present and anterior chamber is

diagnosed at an early stage I i.e., when tumour is

involved.

involving less than half of retina and optic nerve is

The eyeball should be enucleated along with maximum

not involved (usually in the second eye of bilateral

length of the optic nerve taking special care not to

cases), it may be treated conservatively by any one

perforate the eyeball.

or more of the following tumour destructive methods

If optic nerve shows invasion, postoperative

depending upon the size and location of the tumour:

treatment should include:

Present recomendations are for sequential

Radiotherapy (5000 rads) should be applied to

aggressive local therapy (SALT) comprising of multi-

the orbital apex.

modality therapy as below:

Chemotherapy, consisting of vincristine,

Chemoreduction followed by local therapy

carboplatin, and etoposide which may be

(Cryotherapy, thermochemotherapy or brachy-

therapy) is recommended for large tumours (>12

combined with cyclosporin should be

mm in diameter)

supplemented.

Radiotherapy (external beam radiotherapy i.e.,

3. Palliative therapy is given in following cases

EBRT or brachytherapy) combined with

where prognosis for life is dismal in spite of aggressive

chemotherapy is recommended for medium size

treatment:

tumour <12 mm in diameter and <8mm in thickness).

Retinoblastoma with orbital extension,

Cryotherapy is indicated for a small tumour (<4.5

Retinoblastoma with intracranial extension, and

mm indiameter and <2.5 mm in thickness) located

Retinoblastoma with distant metastasis.

anterior to equator.

Palliative therapy should include combination of :

Laser photocoagulation is used for a small

tumour located posterior to equator <3 mm from

Chemotherapy,

fovea.

Surgical debulking of the orbit or orbital

Thermotherapy with diode laser is used for a

exentration, and

small tumour located posterior to equator away

from macula.

External beam radiotherapy (EBRT)

Note: Exentration of the orbit (a mutilating surgery

commonly performed in the past) is now not preferred

by many surgeons.

Prognosis

1. If untreated the prognosis is almost always bad

and the patient invariably dies. Rarely

spontaneous regression with resultant cure and

shrinkage of the eyeball may occur due to necrosis

followed by calcification; suggesting role of some

immunological phenomenon.

2. Prognosis is fair (survival rate 70-85%) if the

eyeball is enucleated before the occurrence of

extraocular extension.

3. Poor prognostic factors are: Optic nerve

involvement, undifferentiated tumour cells and

Fig. 11.37. CT Scan showing retinoblastoma.

massive choroidal invasion.

284

Comprehensive OPHTHALMOLOGY

ENUCLEATION

tenotomy scissors leaving behind a small stump

It is excision of the eyeball. It can be performed under

carrying the suture. The inferior and superior

local anaesthesia in adults and under general

oblique muscles are hooked out and cut near the

anaesthesia in children.

globe.

3. Cutting of optic nerve (Fig. 11.38C): The eyeball

Indications

is prolapsed out by stretching and pushing down

1. Absolute indications are retinoblastoma and

the eye speculum. The eyeball is pulled out with

malignant melanoma.

the help of sutures passed through the muscle

2. Relative indications are painful blind eye,

stumps. The enucleation scissiors is then

mutilating ocular injuries, anterior staphyloma

introduced along the medial wall up to the

and phthisis bulbi.

posterior aspect of the eyeball. Optic nerve is felt

Surgical techniques (Fig. 11.38).

and then cut with the scissors while maintaining

1. Separation of conjunctiva and Tenon’s capsule

a constant pull on the eyeball.

(Fig. 11.38A): Conjunctiva is incised all around

4. Removal of eyeball: The eyeball is pulled out of

the limbus with the help of spring scissors.

the orbit by incising the remaining tissue adherent

Undermining of the conjunctiva and Tenon’s

to it.

capsule is done combinedly, all around up to the

5. Haemostasis is achieved by packing the orbital

equator, using blunt-tipped curved scissors. This

cavity with a wet pack and pressing it back.

manoeuvre exposes the extraocular muscles.

2. Separation of extraocular muscles (Fig. 11.38B):

6. Inserting an orbital implant

(Fig.

11.38D):

The rectus muscles are pulled out one by one

Preferably an orbital implant (made up of PMMA

with the help of a muscle hook and a 3-0 silk

Medpor or hydroxyapatite) of appropriate size

suture is passed near the insertion of each

should be inserted into the orbit and sutured

muscle. The muscle is then cut with the help of

with the rectus muscles.

Fig. 11.38. Surgical steps of enucleation operation: A, separation of conjunctiva and Tenon’s capsule; B,

separation of extraocular muscles; C, cutting of optic nerve and removal of eyeball; D,

insertion of an orbital implant; and E, closure of the conjunctiva

DISEASES OF THE RETINA

285

7. Closure of conjunctiva and Tenon’s capsule is

from small and miliary to balloon-like angiomas,

done separately. Tenon’s capsule is sutured

followed by appearance of haemorrhages and

horizontally with 6-0 vicryl or chromic catgut.

exudates, resembling eventually the exudative

Conjunctiva is sutured vertically so that

retinopathy of Coats. Massive exudation is frequently

conjunctival fornies are retained deep with 6-0

complicated by retinal detachment which may be

silk sutures (Fig. 11.38 E) which are removed after

prevented by an early destruction of angiomas with

8-10 days.

cryopexy or photocoagulation.

8. Dressing. Antibiotic ointment is applied, lids are

2. Tuberous sclerosis (Bourneville disease). It is

closed and dressing is done with firm pressure

characterised by a classic diagnostic triad of adenoma

using sterile eye pads and a bandage.

sebaceum, mental retardation and epilepsy associated

with hamartomas of the brain, retina and viscera. The

Fitting of artifial prosthetic eye

name tuberous sclerosis is derived from the potato-

Conforme may be used postoperatively so that the

like appearance of the tumours in the cerebrum and

conjuctival fornices are retained deep. A proper sized

other organs. Two types of hamartomas found in the

prosthetic eye can be inserted for good cosmetic

retina are: (1) relatively flat and soft appearing white

appearance (Fig. 11.39) after 6 weeks when healing of

or grey lesions usually seen in the posterior pole;

the enucleated socket is complete.

and (2) large nodular tumours having predilection for

the region of the optic disc.

PHAKOMATOSES

3. Neurofibromatosis (von Recklinghausen’s

Phacomatoses or neurocutaneous syndromes refer

disease). It is characterised by multiple tumours in

to a group of familial conditions (having autosomal

the skin, nervous system and other organs. Cutaneous

dominant transmission) which are characterised by

manifestations are very characteristic and vary from

development of neoplasms in the eye, skin and central

cafe-au-lait spots to neurofibromata. Ocular

nervous system. Phakomatoses includes the following

manifestations include neurofibromas of the lids and

conditions:

orbit, glioma of optic nerve and congenital glaucoma.

1. Angiomatosis retinae (Von Hippel Lindau’s

4. Encephalofacial angiomatosis (Sturge-Weber

syndrome). This is a rare condition affecting males

more often than females, in the third and fourth decade

syndrome). It is characterised by angiomatosis in the

of life. The angiomatosis involves retina, brain, spinal

form of port-wine stain (naevus flammeus), involving

cord, kidneys and adrenals. The usual clinical course

one side of the face which may be associated with

of angiomatosis retinae comprises vascular dilatation,

choroidal haemangioma, leptomeningeal angioma and

tortuosity and formation of aneurysms which vary

congenital glaucoma on the affected side.

Fig. 11.39. Photographs of a patient without (A) and with (B) artificial eye

CHAPTER

Neuro-ophthalmology

ANATOMY AND PHYSIOLOGY

SYMPTOMATIC DISTURBANCES OF VISION

Anatomy of visual pathway

Night blindness

Day blindness

Pathway of visual sensations versus

Colour blindness

somatic sensations

Amaurosis

Amblyopia

LESIONS OF THE VISUAL PATHWAY

Cortical blindness

Malingering

PUPILLARY REFLEXES AND THEIR

Hysterical blindness

ABNORMALITIES

Disorders of higher visual functions

DISEASES OF THE OPTIC NERVE

OCULAR MANIFESTATIONS OF DISEASES OF

CENTRAL NERVOUS SYSTEM

Congenital anomalies

Infections

Optic neuritis

Aneurysms

Anterior ischaemic optic neuropathy

Intracranial haemorrhages

Papilloedema

ICSOLs

Optic atrophy

Demyelinating diseases

Tumours

Head injury

peripheral nerves it is not covered by neurilemma (so

ANATOMY AND PHYSIOLOGY

it does not regenerate when cut). The fibres of optic

nerve, numbering about a million, are very fine (2-10

ANATOMY OF THE VISUAL PATHWAY

µm in diameter as compared to 20 µm of sensory

nerves).

The visual pathway starting from retina consists of

Parts of optic nerve. The optic nerve is about 47-50

optic nerves, optic chiasma, optic tracts, lateral

mm in length, and can be divided into 4 parts:

geniculate bodies, optic radiations and the visual

intraocular (1 mm), intraorbital (30 mm), intra-

cortex (Fig. 12.1).

canalicular (6-9 mm) and intracranial (10 mm).

Optic nerve

1. Intraocular part passes through sclera

Each optic nerve (second cranial nerve) starts from

(converting it into a sieve-like structure—the

the optic disc and extends up to optic chiasma, where

lamina cribrosa), choroid and finally appears inside

the two nerves meet. It is the backward continuation

the eye as optic disc (see page 249).

of the nerve fibre layer of the retina, which consists

2. Intraorbital part extends from back of the eye-

of the axons originating from the ganglion cells. It

ball to the optic foramina. This part is slightly

also contains the afferent fibres of the pupillary light

sinuous to give play for the eye movements.

reflex.

Posteriorly, near the optic foramina, it is closely

Morphologically and embryologically, the optic

surrounded by the annulus of Zinn and the

nerve is comparable to a sensory tract. Unlike

origin of the four rectus muscles. Some fibres of

288

NEURO-OPHTHALMOLOGY

288

Optic tracts

These are cylindrical bundles of nerve fibres running

outwards and backwards from the posterolateral

aspect of the optic chiasma. Each optic tract consists

of fibres from the temporal half of the retina of the

same eye and the nasal half of the opposite eye.

Posteriorly each optic tract ends in the lateral

geniculate body. The pupillary reflex fibres pass on

to pretectal nucleus in the midbrain through the

superior brachium. some fibres terminate in the

superior colliculus.

Lateral geniculate bodies

These are oval structures situated at the posterior

termination of the optic tracts. Each geniculate body

consists of six layers of neurons (grey matter)

alternating with white matter (formed by optic fibres).

Fig. 12.1. Components of the visual pathway.

The fibres of second-order neurons coming via optic

tracts relay in these neurons.

superior rectus muscle are adherent to its sheath

here, and accounts for the painful ocular

Optic radiations

movements seen in retrobulbar neuritis.

These extend from the lateral geniculate bodies to

Anteriorly, the nerve is separated from the ocular

the visual cortex and consist of the axons of third-

muscles by the orbital fat.

order neurons of visual pathway.

Intracanalicular part is closely related to the

ophthalmic artery which lies inferolateral to it and

Visual cortex

crosses obliquely over it, as it enters the orbit, to

It is located on the medial aspect of the occipital lobe,

lie on its medial side. Sphenoid and posterior

above and below the calcarine fissure. It is subdivided

ethmoidal sinuses lie medial to it and are separated

into the visuosensory area (striate area 17) that

by a thin bony lamina. This relation accounts for

receives the fibres of the radiations, and the

retrobulbar neuritis following infection of the

surrounding visuopsychic area (peristriate area 18

sinuses.

and parastriate area 19).

Intracranial part of the optic nerve lies above

the cavernous sinus and converges with its fellow

Blood supply of the visual pathway

(over the diaphragma sellae) to form the optic

The visual pathway is mainly supplied by pial network

chiasma.

of vessels except the orbital part of optic nerve which

Meningeal sheaths. Pia mater, arachnoid and dura

is also supplied by an axial system derived from the

covering the brain are continuous over the optic

central artery of retina. The pial plexus around

nerves. In the optic canal the dura is firmly adherent

different parts of the visual pathway gets contribution

with the surrounding bone. The subarachnoid and

from different arteries as shown in Fig. 12.2.

subdural spaces around the optic nerve are also

Blood supply of the optic nerve head (Fig. 12.3) needs

continuous with those of the brain.

special mention.

Optic chiasma

The surface layer of the optic disc is supplied by

It is a flattened structure measuring

12 mm

capillaries derived from the retinal arterioles.

(horizontally) and 8 mm (anterioposteriorly). It lies

The prelaminar region is mainly supplied by

over the tuberculum and diaphragma sellae. Fibres

centripetal branches of the peripapillary choroid

originating from the nasal halves of the retina

with some contribution from the vessels of lamina

decussate at the chiasma.

cribrosa.

NEURO-OPHTHALMOLOGY

289

The lamina cribrosa is supplied by branches

plexus formed by branches from the choroidal

from the posterior ciliary arteries and arterial

arteries, circle of Zinn, central retinal artery and

circle of Zinn.

ophthalmic artery.

The retrolaminar part of the optic nerve is

PATHWAY OF VISUAL SENSATIONS VERSUS

supplied by centrifugal branches from central

SOMATIC SENSATIONS

retinal artery and centripetal branches from pial

The pathway of somatic as well as visual sensations

consists of three neurons

(Fig.

12.4). The

corresponding parts of the pathway of these

sensations are shown in Table 12.1.

Table 12.1. Somatic vs. visual sensations

Feature

Somatic

Visual

sensation

1. Sensory

Nerve endings Rods and cones

end organ

in the skin

2. Neurons of

Lie in posterior

Lie in bipolar

first order

cells root

of the retina

ganglion

3. Neurons of

Lie in nucleus

Lie in ganglion

second order gracilis or

cells of the retina

cuneatus

4. Neurons of

Lie in thalamus Lie in geniculate

third order

body

Fig. 12.2. Blood supply of posterior visual pathway.

Fig. 12.3. Blood supply of the optic nerve.

290

Comprehensive OPHTHALMOLOGY

dilatation due to obstructive hydrocephalus and

chronic chiasmal arachnoiditis.

4. Lateral chiasmal lesions. Salient features of such

lesions are binasal hemianopia associated with binasal

hemianopic paralysis of the pupillary reflexes. These

usually lead to partial descending optic atrophy.

Common causes of such lesions are distension of

third ventricle causing pressure on each side of the

chiasma and atheroma of the carotids or posterior

communicating arteries.

5. Lesions of optic tract. These are characterised by

incongruous homonymous hemianopia associated

with contralateral hemianopic pupillary reaction

(Wernicke’s reaction). These lesions usually lead to

partial descending optic atrophy and may be

associated with contralateral third nerve paralysis and

ipsilateral hemiplegia. Common causes of optic tract

Fig. 12.4. Pathway of visual sensations (B)

lesions are syphilitic meningitis or gumma,

versus somatic sensations (A).

tuberculosis and tumours of optic thalamus and

aneurysms of superior cerebellar or posterior cerebral

LESIONS OF THE VISUAL PATHWAY

arteries.

6. Lesions of lateral geniculate body. These produce

Salient features and important causes of lesions of

homonymous hemianopia with sparing of pupillary

the visual pathway at different levels (Fig. 12.5) are

reflexes, and may end in partial optic atrophy.

as follows:

7. Lesions of optic radiations. Their features vary

1. Lesions of the optic nerve. These are characterised

depending upon the site of lesion. Involvement of

by marked loss of vision or complete blindness on

total optic radiations produce complete homonymous

the affected side associated with abolition of the direct

hemianopia (sometimes sparing the macula). Inferior

light reflex on the ipsilateral side and consensual on

quadrantic hemianopia (pie on the floor) occurs in

the contralateral side. Near (accommodation) reflex is

lesions of parietal lobe (containing superior fibres of

present. Common causes of optic nerve lesions are:

optic radiations). Superior quadrantic hemianopia (pie

optic atrophy, traumatic avulsion of the optic nerve,

in the sky) may occur following lesions of the

indirect optic neuropathy and acute optic neuritis.

temporal lobe (containing inferior fibres of optic

2. Lesions through proximal part of the optic nerve.

radiations). Pupillary reactions are normal as the fibres

Salient features of such lesions are: Ipsilateral

of the light reflex leave the optic tracts to synapse in

blindness, contralateral hemianopia and abolition of

the superior colliculi. Lesions of optic radiations do

direct light reflex on the affected side and consensual

not produce optic atrophy, as the second order

on the contralateral side. Near reflex is intact.

neurons (optic nerve fibres) synapse in the lateral

3. Sagittal (central) lesions of the chiasma. These

geniculate body. Common lesions of the optic

are characterised by bitemporal hemianopia and

radiations include vascular occlusions, primary and

bitemporal hemianopic paralysis of pupillary reflexes.

secondary tumours, and trauma.

These usually lead to partial descending optic

8. Lesions of the visual cortex. Congruous

atrophy. Common causes of central chiasmal lesion

homonymous hemianopia (usually sparing the macula,

are: suprasellar aneurysms, tumours of pituitary

is a feature of occlusion of posterior cerebral artery

gland, craniopharyngioma, suprasellar meningioma

supplying the anterior part of occipital cortex.

and glioma of third ventricle, third ventricular

Congruous homonymous macular defect occurs in

NEURO-OPHTHALMOLOGY

291

Fig. 12.5. Lesions of the visual pathways at the level of : 1. Optic nerve; 2. Proximal part of optic nerve;

3. Central chiasma; 4. Lateral chiasma (both sides); 5. Optic tract; 6. Geniculate body; 7. Part of optic radiations in temporal

lobe; 8. Part of optic radiations in parietal lobe; 9. Optic radiations; 10. Visual cortex sparing the macula;

11. Visual cortex, only macula.

lesions of the tip of the occipital cortex following head

pupil is called consensual (indirect) light reflex. Light

injury or gun shot injuries. Pupillary light reflexes are

reflex is initiated by rods and cones.

normal and optic atrophy does not occur following

Pathway of light reflex (Fig. 12.6). The afferent fibres

visual cortex lesions.

extend from retina to the pretectal nucleus in the mid-

brain. These travel along the optic nerve to the optic

PUPILLARY REFLEXES AND

chiasma where fibres from the nasal retina decussate

THEIR ABNORMALITIES

and travel along the opposite optic tract to terminate

in the contralateral pretectal nucleus. While the fibres

PUPILLARY REFLEXES

from the temporal retina remain uncrossed and travel

Light reflex

along the optic tract of the same side to terminate in

When light is shone in one eye, both the pupils

the ipsilateral pretectal nucleus.

constrict. Constriction of the pupil to which light is

Internuncial fibres connect each pretectal nucleus

shone is called direct light reflex and that of the other

with Edinger-Westphal nuclei of both sides. This

292

Comprehensive OPHTHALMOLOGY

tract, lateral geniculate body, optic radiations, and

striate cortex. From the parastriate cortex the impulses

are relayed to the Edinger- Westphal nucleus of both

sides via the occipito-mesencephalic tract and the

pontine centre. From the Edinger-Westphal nucleus

the efferent impulses travel along the 3rd nerve and

reach the sphincter pupillae and ciliary muscle after

relaying in the accessory and ciliary ganglions.

Psychosensory reflex

It refers to dilatation of the pupil in response to

sensory and psychic stimuli. It is very complex and

its mechanism is still not elucidated.

EXAMINATION OF PUPILLARY REFLEXES

Fig. 12.6. Pathway of the light reflex.

(see page 474)

connection forms the basis of consensual light reflex.

ABNORMALITIES OF PUPILLARY REACTIONS

Efferent pathway consists of the parasympathetic

1. Amaurotic light reflex. It refers to the absence of

fibres which arise from the Edinger-Westphal nucleus

direct light reflex on the affected side (say right eye)

in the mid-brain and travel along the third

and absence of consensual light reflex on the normal

(oculomotor) cranial nerve. The preganglionic fibres

side (i.e., left eye). This indicates lesions of the optic

enter the inferior division of the third nerve and via

nerve or retina on the affected side (i.e., right eye),

the nerve to the inferior oblique reach the ciliary

leading to complete blindness. In diffuse illumination

ganglion to relay. Post-ganglionic fibres travel along

both pupils are of equal size.

the short ciliary nerves to innervate the sphincter

2. Efferent pathway defect. Absence of both direct

pupillae.

and consensual light reflex on the affected side (say

Near reflex

right eye) and presence of both direct and consensual

Near reflex occurs on looking at a near object. It

light reflex on the normal side (i.e., left eye) indicates

consists of two components: (a) convergence reflex,

efferent pathway defect (sphincter paralysis). Near

i.e., contraction of pupil on convergence; and

reflex is also absent on the affected side. Its causes

(b) accommodation reflex, i.e., contraction of pupil

include: effect of parasympatholytic drugs (e.g.,

associated with accommodation.

atropine, homatropine), internal ophthalmoplegia,

Pathway of convergence reflex (Fig. 12.7). Its afferent

and third nerve paralysis.

pathway is still not elucidated. It is assumed that the

3. Wernicke’s hemianopic pupil. It indicates lesion

afferents from the medial recti travel centrally via the

of the optic tract. In this condition light reflex

third nerve to the mesencephalic nucleus of the fifth

(ipsilateral direct and contralateral consensual) is

nerve, to a presumptive convergence centre in the

absent when light is thrown on the temporal half of

tectal or pretectal region. From this the impulse is

the retina of the affected side and nasal half of the

relayed to the Edinger-Westphal nucleus and the

opposite side; while it is present when the light is

subsequent efferent pathway of near reflex is along

thrown on the nasal half of the affected side and

the 3rd nerve. The efferent fibres relay in the

temporal half of the opposite side.

accessory ganglion before reaching the sphincter

pupillae.

4. Marcus Gunn pupil. It is the paradoxical response

Pathway of accommodation reflex (Fig. 12.7). The

of a pupil of light in the presence of a relative afferent

afferent impulses extend from the retina to the

pathway defect (RAPD). It is tested by swinging flash

parastriate cortex via the optic nerve, chiasma, optic

light test. For details see page 474.

294

Comprehensive OPHTHALMOLOGY

Symptoms. Optic neuritis may be asymptomatic or

DISEASES OF THE OPTIC NERVE

may be associated with following symptoms:

Congenital anomalies (see pages 252).

Visual loss. Sudden, progressive and profound

Optic neuritis

visual loss is the hallmark of acute optic neuritis.

Anterior ischaemic optic neuropathy

Dark adaptation may be lowered.

Papilloedema

Visual obscuration in bright light is a typical

Optic atrophy

symptom of acute optic neuritis.

Tumours (see pages 394).

Impairment of colour vision is always present in

optic neuritis. Typically the patients observe

OPTIC NEURITIS

reduced vividness of saturated colours.

Optic neuritis includes inflammatory and demye-

Movement phosphenes and sound induced

linating disorders of the optic nerve.

phosphenes may be percieved by patients with

optic neuritis. Phosphenes refer to glowing

Etiology

sensations produced by nonphotic or the so

1. Idiopathic. In a large proportion of cases the

called inadequate stimuli.

underlying cause is unidentifiable.

Episodic transient obscuration of vision on

2. Hereditary optic neuritis (Leber’s disease)

exertion and on exposure to heat, which recovers

3. Demyelinating disorders are by far the most

on resting or moving away from the heat

common cause of optic neuritis. These include

(Uhthoff’s symptom) occurs in patient with

multiple sclerosis, neuromyelitis optica (Devic’s

isolated optic neuritis.

disease) and diffuse periaxial encephalitis of

Schilder. About 70% cases of established multiple

Depth perception, particularly for the moving

sclerosis may develop optic neuritis.

object may be impaired (Pulfrich’s phenomenon).

4. Parainfectious optic neuritis is associated with

Pain. Patient may complain of mild dull eyeache.

various viral infections such as measles, mumps,

It is more marked in patients with retrobulbar

chickenpox, whooping cough and glandular fever.

neuritis than with papillitis. Pain is usually

It may also occur following immunization.

aggravated by ocular movements, especially in

5. Infectious optic neuritis may be sinus related

upward or downward directions due to

(with acute ethmoiditis) or associated with cat

attachment of some fibres of superior rectus to

scratch fever, syphilis

(during primary or

the dura mater.

secondary stage), lyme disease and cryptococcal

Signs are as follows:

meningitis in patients with AIDS.

1. Visual acuity is usually reduced markedly.

6. Toxic optic neuritis (see toxic amblyopias).

2. Colour vision is often severely impaired.

3. Pupil shows ill-sustained constriction to light.

Clinical profile

Marcus Gunn pupil which indicates relative

Anatomical types. Optic neuritis can be classified

afferent pupillary defect (RAPD) is a diagnostic

into three anatomical types:

sign. It is detected by the swinging flash light

Papillitis. It refers to involvement of the optic

test (see page 474).

disc in inflammatory and demyelinating disorders.

4. Ophthalmoscopic features. Papillitis is

This condition is usually unilateral but sometimes

characterised by hyperaemia of the disc and

may be bilateral.

blurring of the margins. Disc becomes oedematous

Neuroretinitis refers to combined involvement of

and physiological cup is obliterated. Retinal veins

optic disc and surrounding retina in the macular

are congested and tortuous. Splinter haemorrh-

area.

ages and fine exudates may be seen on the disc.

Retrobulbar neuritis is characterized by

Slit-lamp examination may reveal inflammatory

involvement of optic nerve behind the eyeball.

Clinical features of acute retrobulbar neuritis are

cells in the vitreous. Inflammatory signs may also

essentially similar to that of acute papillitis except

be present in the surrounding retina when papillitis

for the fundus changes and ocular changes

is associated with macular star formation and the

described below.

condition is labelled as ‘neuroretinitis’ (Fig. 12.8).

NEURO-OPHTHALMOLOGY

295

visual recovery is slower than the rate of visual loss

and usually takes between 4 and 6 weeks. About 75

to 90 percent cases get good visual recovery.

However, recurrent attacks of acute retrobulbar

neuritis are followed by primary optic atrophy and

recurrent attack of papillitis are followed by

postneuritic optic atrophy leading to complete

blindness.

Treatment

Efforts should be made to find out and treat the

underlying cause. There is no effective treatment for

idiopathic and hereditary optic neuritis and that

associated with demyelinating disorders.

Corticosteroid therapy may shorten the period of

visual loss, but will not influence the ultimate level of

visual recovery in patients with optic neuritis. Optic

Fig. 12.8. Fundus photograph showing

papillitis/neuroretinitis.

neuritis treatment trial (ONTT) group has made

following recommendations for the use of

corticosteroids:

In majority of the cases with retrobulbar neuritis

1. Oral prednisolone therapy alone is contraindicated

fundus appears normal and the condition is

in the treatment of acute optic neuritis, since, it

typically defined as a disease where neither the

did not improve visual outcome and was

ophthalmologist nor the patient sees anything.

associated with a significant increase in the risk

Occasionally temporal pallor of the disc may be

of new attacks of optic neuritis.

seen.

2. A patient presenting with acute optic neuritis

Visual field changes. The most common field

should have brain MRI scan. If the brain shows

defect in optic neuritis is a relative central or

lesions supportive of multiple sclerosis

(MS),

centrocaecal scotoma. Other field defects noted

regardless of the severity of visual loss, each

rarely include: paracentral nerve fibre bundle

patient should receive immediate intravenous

defect, a nerve fibre bundle defect extending up

methylprednisolone

(1 gm daily) for

3 days

to periphery and a nerve fibre bundle defect

followed by oral prednisolone (1 mg/kg/day) for

involving fixation point and periphery. The field

11 days. This therapy will delay conversion to

defects are more marked to red colour than the

clinical MS over the next 2 years.

white.

3. Indications for intravenous methylprednisolone

Contrast sensitivity is impaired.

in acute optic neuritis patients with a normal

Visually evoked response (VER) shows reduced

brain MRI scan are:

amplitude and delay in the transmission time.

Visual loss in both eyes simultaneously or

Differential diagnosis

subsequently within hours or days of each

Papillitis should be differentiated from

other.

When the only good eye is affected.

papilloedema and pseudo-papilloedema

(see

When the slow progressive visual loss

Table 12.2).

continues to occur.

Acute retrobulbar neuritis. It must be differen-

tiated from malingering, hysterical blindness,

LEBER’S DISEASE

cortical blindness and indirect optic neuropathy.

It is a type of hereditary optic neuritis which primarily

Evolution, recovery and complications

affects males around the age of 20 years. It is

In optic neuritis, typically, the visual acuity and colour

transmitted by the female carriers. The condition is

vision is lost progressively over 2-5 days. The rate of

characterised by progressive visual failure. The

296

Comprehensive OPHTHALMOLOGY

fundus is initially normal or in the acute stage disc

Treatment. It consists of complete cessation of

may be mildly hyperaemic with telangiectatic

tobacco and alcohol consumption, hydroxycobal-

microangiopathy. Eventually bilateral primary optic

amine 1000 µg intramuscular injections weekly for 10

atrophy ensues.

weeks and care of general health and nutrition.

Vasodilators have also been tried.

TOXIC AMBLYOPIAS

Prognosis. It is good, if complete abstinence from

These include those conditions wherein visual loss

tobacco and alcohol is maintained. Visual recovery is

results from damage to the optic nerve fibres due to

slow and may take several weeks to months.

the effects of exogenous (commonly) or endogenous

(rarely) poisons.

Ethyl alcohol amblyopia

A few common varieties of toxic amblyopia are

It usually occurs in association with tobacco

described here.

amblyopia. However, it may also occur in non-smokers,

who are heavy drinkers suffering from chronic

Tobacco amblyopia

gastritis. The optic neuritis occurs along with the

It typically occurs in men who are generally pipe

peripheral neuritis of chronic and debilitated

smokers, heavy drinkers and have a diet deficient in

alcoholics.

proteins and vitamin B complex; and thence also

Clinical picture and treatment is similar to tobacco

labelled as ‘tobacco-alcohol-amblyopia.

amblyopia, but the prognosis is not so good.

Pathogenesis. The toxic agent involved is cyanide

Methyl alcohol amblyopia

found in tobacco. The pathogenesis is summarised

Unlike ethyl alcohol (which produces chronic

in Fig. 12.9.

amblyopia), poisoning by methyl alcohol (methanol)

Clinical features. The condition usually occurs in

is typically acute, usually resulting in optic atrophy

men between 40 and 60 years and is characterised by

and permanent blindness.

bilateral gradually progressive impairment in the

Etiology. It usually occurs due to intake of wood

central vision. Patients usually complain of fogginess

alcohol or methylated spirit in cheap adulterated or

and difficulty in doing near work. Visual field

fortified beverages. Sometimes, it may also be

examination reveals bilateral centrocaecal scotomas

absorbed by inhalation of fumes in industries, where

with diffuse margins which are not easily defined.

methyl alcohol is used as a solvent. Rarely it may

The defect is greater for red than the white colour.

also be absorbed from the skin following prolonged

Fundus examination is essentially normal or there

daily use of liniments.

may be slight temporal pallor of the disc.

Pathogenesis. Methyl alcohol is metabolised very

slowly and thus stays for a longer period in the body.

It is oxidised into formic acid and formaldehyde in

Excessive tobacco

Decreased cyanide

the tissues. These toxic agents cause oedema followed

smoking

detoxification due to

by degeneration of the ganglion cells of the retina,

alcoholic’s dietery

deficiency of sulph-

resulting in complete blindness due to optic atrophy.

ur rich proteins

Clinical features. General symptoms of acute

↓

poisoning are headache, dizziness, nausea, vomiting,

Excessive cyanide in blood

abdominal pain, delirium, stupor and even death.

↓

Presence of a characteristic odour due to excretion

Degeneration of ganglion cells

particularly of the macular region

of formaldehyde in the breath or sweat is a helpful

↓

diagnostic sign.

Degeneration of papillo-macular

Ocular features. Patients are usually brought with

bundle in the nerve

almost complete blindness, which is noticed after 2-3

↓

days, when stupor weans off. Fundus examination

Toxic amblyopia

in early cases reveals mild disc oedema and markedly

narrowed blood vessels. Finally bilateral primary

Fig. 12.9. Flow chart depicting pathogenesis

of tobacco amblyopia.

optic atrophy ensues.

NEURO-OPHTHALMOLOGY

297

Treatment

ANTERIOR ISCHAEMIC OPTIC NEUROPATHY

(AION)

1. Gastric lavage to wash away the methyl alcohol

should be carried out immediately and at intervals

It refers to the segmental or generalised infarction of

during the first few days, as the alcohol in the

anterior part of the optic nerve.

system is continuously returned to stomach.

Etiology. The AION results from occlusion of the

short posterior ciliary arteries. Depending upon the

2. Administration of alkali to overcome acidosis

etiology it may be typified as follows:

should be done in early stages. Soda bicarb may

1. Idiopathic AION. It is the most common entity,

be given orally or intravenously (500 ml of 5%

thought to result from the atherosclerotic changes

solution).

in the vessels.

3. Ethyl alcohol. It should also be given in early

2. Arteritic AION. It is the second common variety.

stages. It competes with the methyl alcohol for

It occurs in association with giant cell arteritis.

the enzyme alcohol dehydrogenase, thus

3. AION due to miscellaneous causes. It may be

preventing the oxidation of methanol to

associated with severe anaemia, collagen vascular

formaldehyde. It should be given in small frequent

disorders, following massive haemorrhage,

doses, 90 cc every 3 hours for 3 days.

papilloedema, migraine and malignant

4. Eliminative treatment by diaphoresis in the form

hypertension.

of peritoneal dialysis is also helpful by washing

Clinical features. Visual loss is usually marked and

the alcohol and formaldehyde from the system.

sudden. Fundus examination during acute stage may

5. Prognosis is usually poor; death may occur due

reveal segmental or diffuse oedematous, pale or

to acute poisoning. Blindness often occurs in

hyperaemic disc, usually associated with splinter

those who survive.

haemorrhages.

Visual fields show typical altitudinal hemianopia

Quinine amblyopia

involving the inferior (commonly) or superior half

It may occur even with small doses of the drug in

(Fig. 12.10).

susceptible individuals.

Investigations. ESR and C-reactive protein levels are

Clinical features. Patient may develop near total

raised in patients with giant cell arteritis. Confirmation

blindness. Deafness and tinnitus may be associated.

of the diagnosis may be done by temporal artery

The pupils are fixed and dilated. Fundus examination

biopsy.

reveals retinal oedema, marked pallor of the disc and

extreme attenuation of retinal vessels. Visual fields

are markedly contracted.

Ethambutol amblyopia

Ethambutol is a frequently used antitubercular drug.

It is used in the doses of 15 mg/kg per day. Sometimes,

it may cause toxic optic neuropathy. Ethambutol

toxicity usually occurs in patients who have

associated alcoholism and diabetes.

Clinical features. There may occur optic neuritis with

typical central scotoma. Involvement of optic chiasma

may result in a true bitemporal hemianopia. Patients

usually complain of reduced vision or impairment of

colour vision during the course of antitubercular

treatment. Fundus examination may reveal signs of

papillitis. In most of the cases recovery occurs

following cessation of the intake of drug.

Fig. 12.10. Altitudinal hemianopia in AION.

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Comprehensive OPHTHALMOLOGY

Treatment. Immediate treatment with heavy doses of

medulla oblongata may induce papilloedema.

corticosteroids (80 mg prednisolone daily) should be

Papilloedema is most frequently associated with

started and tapered by 10 mg weekly. Steroids in small

tumours arising in posterior fossa, which obstruct

doses (5 mg prednisolone) may have to be continued

aqueduct of Sylvius and least with pituitary

for a long time (3 months to one year).

tumours. Thus, the ICSOLs of cerebellum,

midbrain and parieto-occipital region produce

PAPILLOEDEMA

papilloedema more rapidly than the mass lesions

The terms papilloedema and disc oedema look alike

of other areas. Further, the fast progressing lesions

and per se mean swelling of the optic disc. However,

produce papilloedema more frequently and acutely

arbitrarily the term ‘papilloedema’ has been reserved

than the slow growing lesions.

for the passive disc swelling associated with

Intracranial infections such as meningitis and

increased intracranial pressure which is almost always

encephalitis may be associated with papilloedema.

bilateral although it may be asymmetrical. The term

Intracranial haemorrhages. Cerebral as well as

‘disc oedema or disc swelling’ includes all causes of

subarachnoid haemorrhage can give rise to

active or passive oedematous swelling of the optic

papilloedema which is frequent and considerable

disc.

in extent.

Obstruction of CSF absorption via arachnoid

Causes of disc oedema

villi which have been damaged previously.

1. Congenital anomalous elevation

(Pseudo-

Tumours of spinal cord occasionally give rise to

papilloedema)

papilloedema.

2. Inflammations

Idiopathic intracranial hypertension (IIH) also

Papillitis

known as pseudotumour cerebri,is an important

Neuroretinitis

cause of raised intracranial pressure. It is a poorly

3. Ocular diseases

understood condition, usually found in young

Uveitis

obese women. It is characterised by chronic

Hypotony

headache and bilateral papilloedema without any

Vein occlusion

ICSOLs or enlargement of the ventricles due to

4. Orbital causes

hydrocephalus.

Tumours

Systemic conditions include malignant

Graves’ orbitopathy

hypertension, pregnancy induced hypertension

Orbital cellulitis

(PIH) cardiopulmonary insufficiency, blood

5. Vascular causes

dyscrasias and nephritis.

Anaemia

Diffuse cerebral oedema from blunt head trauma

Uremia

may causes papilloedema

Anterior ischaemic optic neuropathy

Unilateral versus bilateral papilloedema. Disc

6. Increased intracranial pressure

swelling due to ocular and orbital lesions is usually

See causes of papilloedema

unilateral. In majority of the cases with raised

Etiopathogenesis of papilloedema

intracranial pressure, papilloedema is bilateral.

Causes. As discussed above, papilloedema occurs

However, unilateral cases as well as of unequal

secondary to raised intracranial pressure which may

change do occur with raised intracranial pressure. A

be associated with following conditions:

few such conditions are as follows:

1. Congenital conditions include aqueductal

1. Foster-Kennedy syndrome. It is associated with

stenosis and craniosynostosis.

olfactory or sphenoidal meningiomata and frontal

2. Intracranial space-occupying lesions (ICSOLs).

lobe tumours. In this condition, there occurs

These include brain tumours, abscess,

pressure optic atrophy on the side of lesion and

tuberculoma, gumma, subdural haemotoma and

papilloedema on the other side (due to raised

aneurysms. The ICSOLs in any position excepting

intracranial pressure).

NEURO-OPHTHALMOLOGY

299

2. Pseudo-Foster-Kennedy syndrome. It is

under four stages: early, fully developed, chronic and

characterised by occurrence of unilateral

atrophic.

papilloedema associated with raised intracranial

Early (incipient) papilloedema

pressure (due to any cause) and a pre-existing

Symptoms are usually absent and visual acvity is

optic atrophy (due to any cause) on the other

normal.

side.

Pupillary reactions are normal.

Pathogenesis. It has been a confused and

Ophthalmoscopic features of early papilloedema

controversial issue. Various theories have been put

are (Fig.

12.11A): (i) Obscuration of the disc

forward and discarded from time to time. Till date,

margins (nasal margins are involved first followed

Hayreh’s theory is the most accepted one. It states

by the superior, inferior and temporal) (ii) Blurring

that, ‘papilloedema develops as a result of stasis of

of peripapillary nerve fibre layer. (iii) Absence of

axoplasm in the prelaminar region of optic disc, due

spontaneous venous pulsation at the disc

to an alteration in the pressure gradient across the

(appreciated in 80% of the normal individuals).

lamina cribrosa.’

(iv) Mild hyperaemia of the disc. (v) Splinter

Increased intracranial pressure, malignant

haemorrhages in the peripapillary region may be

hypertension and orbital lesions produce disturbance

present.

in the pressure gradient by increasing the tissue

Visual fields are fairly normal.

pressure within the retrolaminar region. While, ocular

Established (fully developed) papilloedema

hypotony alters it by lowering the tissue pressure

Symptoms. Patient may give history of transient

within the prelaminar area.

visual obscurations in one or both eyes, lasting

Thus the axonal swelling in prelaminar region is

a few seconds, after standing. Visual acuity is

the initial structural alteration, which in turn produces

usually normal,

venous congestion and ultimately the extracellular

Pupillary reaction remain fairly normal,

oedema. This theory discards the most popular view

Ophthalmoscopic features

(Fig.

12.11B):

(i)

that the papilloedema results due to compression of

Apparent optic disc oedema is seen as its forward

the central retinal vein by the raised cerebrospinal

elevation above the plane of retina; usually up to

fluid pressure around the optic nerve.

1-2 mm (1 mm elevation is equivalent to +3

Evolution and recovery. Papilloedema usually

dioptres). (ii) Physiological cup of the optic disc

develops quickly, appearing within 1-5 days of raised

is obliterated.

(iii) Disc becomes markedly

intracranial pressure.

hyperaemic and blurring of the margin is present

In cases with acute subarachnoid haemorrhage it

all-around.

(iv) Multiple soft exudates and

may develop even more rapidly (within 2-8 hours).

superficial haemorrhages may be seen near the

However, recovery from fully developed papilloedema

disc. (v) Veins becomes tortuous and engorged.

is rather slow. It takes about 6-8 weeks to subside

(vi) In advanced cases, the disc appears to be

after the intracranial pressure is normalised.

enlarged and circumferential greyish white folds

Clinical features

may develop due to separation of nerve fibres by

the oedema. (vii) Rarely, hard exudates may radiate

[A] General features. Patients usually present to

general physicians with general features of raised

from the fovea in the form of an incomplete star.

intracranial pressure. These include headache,

Visual fields show enlargement of blind spot.

nausea, projectile vomiting and diplopia. Focal

Chronic or long standing (vintage) papilloedema

neurological deficit may be associated.

Symptoms. Visual acuity is variably reduced

[B] Ocular features. Patients may give history of

depending upon the duration of the papilloedema.

recurrent attacks of transient blackout of vision

Pupillary reactions are usually normal

(amaurosis fugax). Visual acuity and pupillary

Ophthalmoscopic features (Fig. 12.11C). In this

reactions usually remain fairly normal until the late

stage, acute haemorrhages and exudates resolve,

stages of diseases when optic atrophy sets in.

and peripapillary oedema is resorbed. The optic

Clinical features of papilloedema can be described

disc gives appearance of the dome of a

300

Comprehensive OPHTHALMOLOGY

Fig. 12.11. Fundus photograph showing papilloedema: A, Early B, Established; C, Chronic; D, Atrophic.

champagne cork. The central cup remains

Visual fields. Concentric contraction of peripheral

obliterated. Small drusen like crystalline deposits

fields becomes apparent as atrophy sets in.

(corpora amylacea) may appear on the disc

Differential diagnosis

surface.

Papilloedema should be differentiated from pseudo-

Visual fields. Blind spot is enlarged and the

papilloedema and papillitis. Pseudopapilloedema is

visual fields begin to constrict.

a non-specific term used to describe elevation of the

4. Atrophic papilloedema

disc similar to papilloedema, in conditions such as

Symptoms. Atrophic papilloedema develops after

optic disc drusen, hypermetropia, and persistent

6-9 months of chronic papilloedema and is

hyaloid tissue. The differentiating points between

characterized by severely impaired visual acuity.

papilloedema, papillitis and pseudopapilloedema

Pupillary reaction. Light reflex is impaired.

(pseudopapillitis) due to hypermetropia are

Ophthalmoscopic features (Fig. 12.11D)

enumerated in Table 12.2.

It is characterised by greyish white discoloration

and pallor of the disc due to atrophy of the neurons

Treatment and prognosis

and associated gliosis. Prominence of the disc

It is a neurological emergency and requires immediate

decreases in spite of persistent raised intracranial

hospitalisation. As a rule unless the causative disease

pressure. Retinal arterioles are narrowed and veins

is treatable or cerebral decompression is done, the

become less congested. Whitish sheathing develops

course of papilloedema is chronic and ultimate visual

around the vessels.

prognosis is bad.

NEURO-OPHTHALMOLOGY

301

OPTIC ATROPHY

complicating process within the eye e.g., syphilitic

optic atrophy of tabes dorsalis.

It refers to degeneration of the optic nerve, which

occurs as an end result of any pathologic process

Secondary optic atrophy occurs following any

that damages axons in the anterior visual system, i.e.

pathologic process which produces optic neuritis

from retinal ganglion cells to the lateral geniculate

or papilloedema.

body.

Recently, most of the authors have discarded the use

of this time-honoured but non-informative

Classification

classification. Further, such a classification is

A. Primary versus secondary optic atrophy. It is

misleading since identical lesion at disc (e.g. papillitis

customary to divide the optic atrophy into primary

in multiple sclerosis) will produce secondary optic

and secondary.

atrophy and when involving optic nerve a little distance

Primary optic atrophy refers to the simple

up (e.g. retrobulbar neuritis in multiple sclerosis) will

degeneration of the nerve fibres without any

produce an apparently primary optic atrophy.

Table 12.2: Differentiating features of papilloedema, papillitis and pseudopapillitis

Feature

Papilloedema

Papillitis

Pseudopapillitis

Laterality

Usually bilateral

Usually unilateral

May be unilateral

or bilateral

Symptoms

(i)

Visual acuity

Transient

Marked loss of

Defective vision

attacks of blurred

vision of

depending upon

vision

sudden onset

the degree of

Later vision

refractive error

decreases due to

optic atrophy

(ii)

Pain and tenderness

Absent

May be present

Absent

with ocular movements

Fundus examination

(i)

Media

Clear

Posterior

Clear

vitreous haze

is common

(ii)

Disc colour

Red and juicy

Marked

Reddish

appearance

hyperaemia

Disc margins

Blurred

Not well defined

Disc swelling

2-6 dioptres

Usually not

Depending upon the

more than

degree of

3 dioptres

hypermetropia

(iii)

Peripapillary oedema

Present

Absent

(iv) Venous engorgement

More marked

Less marked

Not present

(v) Retinal haemorrhages

Marked

Usually not present

Not present

(vi) Retinal exudates

More marked

Less marked

Absent

(vii) Macula

Macular star may be

Macular fan may be

Absent

present

Fields

Enlarged

Central scotoma

No defect

blind spot

more for colours

Fluorescein angiography

Vertical oval

Minimal

No leakage of dye

pool of dye

leakage of dye

due to leakage

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Comprehensive OPHTHALMOLOGY

B. Ophthalmoscopic classification. It is more useful

antecedent papilloedema. Its common causes are:

to classify optic atrophy based on its ophthalmo-

multiple sclerosis, retrobulbar neuritis (idiopathic),

scopic appearance. Common types are as follows:

Leber’s and other hereditary optic atrophies,

1. Primary (simple) optic atrophy

intracranial tumours pressing directly on the

2. Consecutive optic atrophy

anterior visual pathway (e.g. pituitary tumour),

3. Glaucomatous optic atrophy

traumatic severance or avulsion of the optic nerve,

4. Post-neuritic optic atrophy

toxic amblyopias (chronic retrobulbar neuritis)

5. Vascular (ischaemic) optic atrophy.

and tabes dorsalis.

The etiology and salient features of each type will

2. Consecutive optic atrophy. It occurs following

be considered separately.

destruction of ganglion cells secondary to

degenerative or inflammatory lesions of the

C. Ascending versus descending optic atrophy.

choroid and/or retina. Its common causes are:

Ascending optic atrophy follows damage to

diffuse chorioretinitis, retinal pigmentary

ganglion cells or nerve fibre layer due to disease

dystrophies such as retinitis pigmentosa,

of the retina or optic disc. In it the nerve fibre

pathological myopia and occlusion of central

degeneration progresses

(ascends) from the

retinal artery.

eyeball towards the geniculate body.

3. Postneuritic optic atrophy. It develops as a

Descending or retrograde optic atrophy proceeds

sequelae to long-standing papilloedema or

from the region of the optic tract, chiasma or

papillitis.

posterior portion of the optic nerve towards the

4. Glaucomatous optic atrophy. It results from the

optic disc.

effect of long standing raised intraocular pressure.

Pathological features

5. Vascular (ischaemic) optic atrophy. It results from

Degeneration of the optic nerve fibres is associated

the conditions (other than glaucoma) producing disc

with attempted but unsuccessful regeneration which

ischaemia. These include: giant cell arteritis, severe

is characterised by proliferation of astrocytes and

haemorrhage, severe anaemia and quinine poisoning.

glial tissue. The ophthalmoscopic appearance of the

Clinical features of optic atrophy

atrophic optic disc depends upon the balance

1. Loss of vision, may be of sudden or gradual

between loss of nerve tissue and gliosis. Following

onset

(depending upon the cause of optic

three situations may occur:

atrophy) and partial or total (depending upon the

1. Degeneration of the nerve fibres may be

degree of atrophy). It is important to note that

associated with excessive gliosis. These changes

ophthalmoscopic signs cannot be correlated with

are pathological features of the consecutive and

the amount of vision.

postneuritic optic atrophy.

2. Pupil is semidilated and direct light reflex is very

2. Degeneration and gliosis may be orderly and

sluggish or absent. Swinging flash light test

the proliferating astrocytes arrange themselves in

depicts Marcus Gunn pupil.

longitudinal columns replacing the nerve fibres

(columnar gliosis). Such pathological features are

3. Visual field loss will vary with the distribution of

seen in primary optic atrophy.

the fibres that have been damaged. In general the

3. Degenration of the nerve fibres may be associated

field loss is peripheral in systemic infections,

with negligible gliosis. It occurs due to

central in focal optic neuritis and eccentric when

progressive decrease in blood supply. Such

the nerve or tracts are compressed.

pathological changes are labelled as cavernous

4. Ophthalmoscopic appearance of the disc will

optic atrophy and are features of glaucomatous

vary with the type of optic atrophy. However,

and ischaemic (vascular) optic atrophy.

ophthalmoscopic features of optic atrophy in

general are pallor of the disc and decrease in the

Etiology

number of small blood vessels

(Kastenbaum

1. Primary (simple) optic atrophy. It results from

index). The pallor is not due to atrophy of the

the lesions proximal to the optic disc without

nerve fibres but to loss of vasculature.

NEURO-OPHTHALMOLOGY

303

Ophthalmoscopic features of different types of

SYMPTOMATIC DISTURBANCES

optic atrophy are as described below:

OF THE VISION

i. Primary optic atrophy (Fig. 12.12A). Colour of

the disc is chalky white or white with bluish

NIGHT BLINDNESS (NYCTALOPIA)

hue. Its edges (margins) are sharply outlined.

Slight recession of the entire optic disc occurs

Night (scotopic) vision is a function of rods.

Therefore, the conditions in which functioning of

in total atrophy. Lamina cribrosa is clearly

these nerve endings is deranged will result in night

seen at the bottom of the physiological cup.

blindness. These include vitamin A deficiency,

Major retinal vessels and surrounding retina

tapetoretinal degenerations

(e.g., retinitis

are normal.

pigmentosa), congenital high myopia, familial

ii. Consecutive optic atrophy (Fig. 12.12B). Disc

congenital night blindness and Oguchi’s disease. It

appears yellow waxy. Its edges are not so

may also develop in conditions of the ocular media

sharply defined as in primary optic atrophy.

interfering with the light rays in dim light (i.e. with

Retinal vessels are attenuated.

dilated pupils). These include paracentral lenticular

iii. Post-neuritic optic atrophy (Fig. 12.12C). Optic

and corneal opacities. In advanced cases of primary

disc looks dirty white in colour. Due to gliosis

open angle glaucoma, dark adaptation may be so much

its edges are blurred, physiological cup is

delayed that patient gives history of night blindness.

obliterated and lamina cribrosa is not visible.

Retinal vessels are attenuated and perivascular

DAY BLINDNESS (HAMARLOPIA)

sheathing is often present.

It is a symptomatic disturbance of the vision, in which

iv. Glaucomatous optic atrophy. It is

the patient is able to see better in dimlight as

characterised by deep and wide cupping of

compared to bright light of the day. Its causes are

the optic disc and nasal shift of the blood

congenital deficiency of cones, central lenticular

vessels (for details see page 216 & Fig. 9.10).

opacities (polar cataracts) and central corneal

v. Ischaemic optic atrophy. Ophthalmoscopic

opacities.

features are pallor of the optic disc associated

with marked attenuation of the vessels (Fig.

COLOUR BLINDNESS

12.12D).

An individual with normal colour vision is known as

trichromate. In colour blindness, faculty to

Differential diagnosis

appreciate one or more primary colours is either

Pallor of optic disc seen in partial optic atrophy must

defective (anomalous) or absent (anopia). It may be

be differentiated from other causes of pallor disc which

congenital or acquired.

may be non-pathological and pathological.

1. Non-pathological pallor of optic disc is seen in:

A. Congenital Colour Blindness.

axial myopia, infants, and elderly people with

It is an inherited condition affecting males more

sclerotic changes. Temporal pallor is associated

(3-4%) than females (0.4%). It may be of the following

with large physiological cup.

types:

2. Pathological causes of pallor disc (other than

Dyschromatopsia

optic atrophy) include hypoplasia, congenital pit,

Achromatopsia

and coloboma.

1. Dyschromatopsia

Treatment

Dyschromatopsia, literally means colour confusion

The underlying cause when treated may help in

due to deficiency of mechanism to perceive colours.

preserving some vision in patients with partial optic

It can be classified into:

atrophy. However, once complete atrophy has set in,

Anomalous trichromatism

the vision cannot be recovered.

Dichromatism

NEURO-OPHTHALMOLOGY

305

Deuteranopia, i.e., complete defect for green

follows:

colour.

Pseudo-isochromatic charts. It is the most

commonly employed test using Ishihara’s plates

Tritanopia, i.e., absence of blue colour

(Fig. 12.13). In this there are patterns of coloured

appreciation.

and grey dots which reveal one pattern to the

Red-green deficiency (protanomalous, protanopia,

normal individuals and another to the colour

deuteranomalous and deuteranopia) is more common.

deficients. It is a quick method of screening

Such a defect is a source of danger in certain

colour blinds from the normals. Another test

occupations such as drivers, sailors and traffic police.

based on the same principle is Hardy-Rand-

Blue deficiency (tritanomalous and tritanopia) is

Rittler plates (HRR).

comparatively rare.

The lantern test. In this test the subject has to

name the various colours shown to him by a

2. Achromatopsia

lantern and the judgement is made by the mistake

It is an extremely rare condition presenting as cone

he makes. Edridge-Green lantern is most popular.

monochromatism or rod monochromatism.

Farnsworth-Munsell

100 hue test. It is a

Cone monochromatism is characterised by presence

spectroscopic test in which subject has to arrange

of only one primary colour and thus the person is

the coloured chips in ascending order. The colour

vision is judged by the error score, i.e. greater the

truely colour blind. Such patients usually have a

score poorer the colour vision.

visual acuity of 6/12 or better.

City university colour vision test. It is also a

Rod monochromatism may be complete or

spectroscopic test where a central coloured plate

incomplete. It is inherited as an autosomal recessive

is to be matched to its closest hue from four

trait. It is characterized by:

surrounding colour plates.

Total colour blindness,

Nagel’s anomaloscope. In this test the observer

Day blindness (visual acuity is about 6/60),

is asked to mix red and green colour in such a

Nystagmus,

proportion that the mixture should match the

Fundus is usually normal.

given yellow coloured disc. The judgement about

B. Acquired Colour Blindness.

the defect is made from the relative amount of red

It may follow damage to macula or optic nerve,

and green colours and the brightness setting

used by the observer.

Usually, it is associated with a central scotoma or

Holmgren’s wools test. In this the subject is

decreased visual acuity.

Blue-yellow impairment is seen in retinal lesions

such as CSR, macular oedema and shallow retinal

detachment.

Red-green deficiency is seen in optic nerve

lesions such as optic neuritis, Leber’s optic

atrophy and compression of the optic nerve.

Acquired blue colour defect

(blue blindness)

may occur in old age due to increased sclerosis

of the crystalline lens. It is owing to the physical

absorption of the blue rays by the increased

amber coloured pigment in the nucleus.

Tests for Colour Vision

These tests are designed for : (1) Screening defective

colour vision from normal;

(2) Qualitative

classification of colour blindness i.e., protans,

deuteran and tritan; and (3) Quantitative analysis of

degree of deficiency i.e., mild, moderate or marked.

Commonly employed colour vision tests are as

Fig. 12.13. Ishihara’s pseudo-isochromatic chart.

306

Comprehensive OPHTHALMOLOGY

asked to make a series of colour-matches from a

amblyopia; page 296) or functional.

selection of skeins of coloured wools.

Functional amblyopia results from the psychical

suppression of the retinal image. It may be

AMAUROSIS

anisometropic, strabismic or due to stimulus

It implies complete loss of sight in one or both eyes,

deprivation (amblyopia ex anopsia) (see page 319).

in the absence of ophthalmoscopic or other marked

CORTICAL BLINDNESS

objective signs.

Cortical blindness (visual cortex disease) is produced

1. Amaurosis fugax

by bilateral occipital lobe lesions. Unilateral occipital

It refers to a sudden, temporary and painless

lobe lesions typically produce contralateral macular

monocular visual loss occurring due to a transient

sparing congruous homonymous hemianopia.

failure of retinal circulation.

Causes of cortical blindness include:

Common causes of amaurosis fugax are: carotid

Vascular lesions producing bilateral occipital

transient ischaemic attacks (TIA), embolization of

infarction are the commonest cause of cortical

retinal circulation, papilloedema, giant cell arteritis,

blindness (e.g., embolisation of posterior cerebral

Raynaud’s disease, migraine, as a prodromal

arteries).

symptom of central retinal artery or carotid artery

Head injury involving bilateral occipital lobes is

occlusion, hypertensive retinopathy, and venous

the second common cause.

stasis retinopathy. An attack of amaurosis fugax is

Tumours, primary (e.g., falcotentorial meningio-

typically described by the patients as a curtain that

mas, bilateral gliomas) or metastatic are rare

descends from above or ascends from below to

causes.

occupy the upper or lower halves of their visual fields.

Other rare causes of cortical blindness are

Clinical characteristics. The attack lasts for two to

migraine, hypoxic encephalopathy, Schilder’s

five minutes and resolves in the reverse pattern of

disease and other leukodystrophies.

progression, leaving no residual deficit. Due to brief

Clinical features. Cortical blindness is characterized

duration of the attack, it is rarely possible to observe

by:

the fundus. When observed shortly after an attack,

Bilateral loss of vision,

the fundus may either be normal or reveal signs of

Normal pupillary light reflexes,

retinal ischemia such as retinal oedema and small

Visual imagination and visual imagery in dream

superficial haemorrhages. In some cases, retinal

are preserved

emboli in the form of white plugs (fibrin-platelet

Anton syndrome i.e., denial of blindness by the

aggregates) may be seen.

patients who obviously cannot see.

Riddoch phenomenon i.e., ability to perceive

2. Uraemic amaurosis

kinetic but not static targets.

It is a sudden, bilateral, complete loss of sight

Management. A thorough neurological and

occurring probably due to the effect of certain toxic

cardiovascular investigative workup including MRI

materials upon the cells of the visual centre in patients

and MRI angiography should be carried out.

suffering from acute nephritis, eclampsia of pregnancy

Treatment depends upon the underlying cause. Partial

and renal failure. The visual loss is associated with

dilated pupils which generally react to light. The fundi

or complete recovery may occur in patients with stroke

are usually normal except for the coincidental findings

progressing from cortical blindness through visual

of hypertensive retinopathy, when associated.

agnosia, and partially impaired perceptual function

Usually, the vision recovers in 12-48 hours.

to recovery.

AMBLYOPIA

MALINGERING

It implies a partial loss of sight in one or both eyes, in

In malingering a person poses to be visually

the absence of ophthalmoscopic or other marked

defective, while he is not. The person may do so to

objective signs. It may be either congenital or

gain some undue advantage or compensation.

acquired. Acquired amblyopia may be organic (toxic

Usually, one eye is said to be blind which does not

NEURO-OPHTHALMOLOGY

307

show any objective sign. Rarely, a person pretends

in red and green. Place a red glass before the

to be completely blind. In such cases, a constant

good eye. If the person can read all the letters,

watch over the behaviour may settle the issue.

it confirms malingering because, normally one

can see only red letters through red glass.

Differential diagnosis

Before diagnosing malingering following conditions

HYSTERICAL BLINDNESS

(which produce visual loss with apparantly normal

It is a form of psychoneurosis, commonly seen in

anterior segment and a normal fundus) should be ruled

attention-seeking personalities, especially females. It

out:

is characterised by sudden bilateral loss of vision

1. Amblyopia. Many a time an individual may

(cf. malingering). The patient otherwise shows little

suddenly notice poor vision in one eye though the

concern for the symptoms and negotiates well with

onset is usually in early childhood. It is important to

the surroundings (c.f. malingering). There may be

identify an amblyogenic factor (see page 319).

associated blepharospasm and lacrimation. Visual

2. Cortical blindness must be ruled out from its

fields are concentrically contracted. One can

characteristic features(see page 306).

commonly find spiral fields as the target moves closer

to the fixation point. Pupillary responses are

3. Retrobulbar neuritis a common cause of visual

essentially normal and so is the blink response.

loss with normal fundus. Presence of a definite or

Optokinetic nystagmus is intact. Its treatment

relative afferent pupillary defect (RAPD) and VER are

includes psychological support and reassurance.

diagnostic.

Placebo tablets may also be helpful. A psychiatrist’s

4. Cone rod dystrophy is characterized by a positive

help should be sought for, if these fail.

family history, photophobia in bright light, abnormal

dark adaptation and abnormal cone dystrophy electro-

DISORDERS OF HIGHER VISUAL FUNCTIONS

retinogram.

Visual agnosia

5. Chiasmal tumours may sometimes present with

Definition. Visual agnosia refers to a rare disorder in

visual loss and normal fundus (before the onset of

which ability to recognise the objects by sight

optic atrophy). Sluggish pupillary reactions to light

(despite adequate visual acuity) is impaired while the

with characteristic visual field defects may be noted.

ability to recognize by touch, smell or sound is

Tests for malingering

retained.

Types of visual agnosia include :

1. Convex lens test. Place a low convex or concave

Prosopagnosia. In it patient cannot recognize

lens (0.25 D) before the blind eye and a high

familiar faces.

convex lens (+10 D) before the good eye. If the

Object agnosia. In it patient is not able to name

patient can read distant words, malingering

and indicate the use of a seen object by spoken

is proved.

or written words or by gestures.

2. Prism base down test. Place a prism with its base

Site of lesion in visual agnosia is bilateral inferior

downwards before the good eye and tell the

(ventromedial) occipitotemporal junction.

person to look at a light source. If the patient

Associated features include :

admits seeing two lights, it confirms malingering.

Bilateral homonymous hemianopia.

3. Prism base out test. Ask the patient to look at a

Dyschromatopsia (disturbance of colour vision).

light source. Then a prism of 10 D is placed

before the alleged blind eye with its base outwards.

Visual hallucinations

If the eye moves inwards (to eliminate diplopia)

Visual hallucinations refers to the conditions in which

malingering is proved.

patient alleges of seeing something that is not evident

4. Snellen’s coloured types test. It has letters printed

to others in the same environment.

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Comprehensive OPHTHALMOLOGY

Types. Visual hallucinations are of two types:

Cerebral diplopia or polyopia are also reported

Elementary

(unformed) hallucinations include

to occur as rare symptoms of central nervous

flashes of light, colours, luminous points, stars,

system disease.

multiple lights and geometric forms. They may be

Causes. Visual illusions are reported to occur in

stationary or moving.

lesions of the occipital, occipitoparietal or

Complex (formed) hallucinations include objects,

occipitotemporal regions, and the right hemisphere

persons or animals.

appears to be involved more often than the left.

Causes of visual hallucinations include:

Occipital and temporal lobe lesions. Elementary

hallucinations are considered to have their origin

OCULAR MANIFESTATIONS

in the occipital cortex and complex ones in the

OF DISEASES OF CENTRAL

temporal cortex.

NERVOUS SYSTEM

Drug induced. Many drugs acting on the CNS in

high doses are hallucinogenic.

Ocular involvement in diseases of the central nervous

Bilateral visual loss in elderly individuals may

system is not infrequent. A few common ocular lesions

be associated with formed hallucinations (Charles

of these diseases are mentioned here.

Bonnet syndrome).

Migraine is a common cause of unformed

INTRACRANIAL INFECTIONS

hallucinations.

Optic nerve diseases and vitreous traction are

These include meningitis, encephalitis, brain abscess

reproted to produce unformed hallucinations.

and neurosyphilis.

Psychiatric disorders are not the causes of

1. Meningitis. It may be complicated by papillitis,

isolated visual hallucinations.

and paralysis of third, fourth and sixth cranial

nerves. Chronic chiasmal arachnoiditis may

Alexia and agraphia

produce bilateral optic atrophy. Tuberculous

Alexia means the inability to read (despite good

meningitis may be associated with choroidal

vision). It is commonly associated with agrphia

tubercles.

(inability to write).

2. Encephalitis. It may be complicated by papillitis

Causes. Alexia associated with agraphia is produced

and/or papilloedema. Cranial nerve palsies are

by lesions of the angulate gyrus of the dominant

usually incomplete. Diplopia and ptosis are often

hemisphere.

present.

Alexia without agraphia is usually caused by lesions

3. Brain abscess. It is frequently associated with

that destroy the visual pathway in the left occipital

papilloedema. Focal signs depend upon the site

lobe and also interrupt the association fibres from

of the abscess, and are thus similar to tumours.

the right occipital lobe that have crossed in the

4. Neurosyphilis. Ocular involvement is quite

splenium of corpus callosum.

frequent. Gummatous meningitis may be

associated with papillitis, papilloedema or

Visual illusions

postneuritic optic atrophy and cranial nerve

In visual illusions patients perceive distortions in

palsies. (Third nerve is paralysed in nearly 30 per

form, size, movement or colour of the objects seen.

cent cases, less frequently the fifth and sixth, and

Some of the visual illusions are:

least frequently the fourth.) Tabes dorsalis and

Palinopsia

(visual perservation) is an illusion

generalised paralysis of insane may be associated

whereby the patient continues to perceive an

with primary optic atrophy, Argyll Robertson

image after the actual object is no longer in view.

pupil, and internal and/or external ophthal-

Optic anaesthesia refers to false orientation of

moplegia.

objects in space.

Cerebral dyschromotopsia may occur as

INTRACRANIAL ANEURYSMS

disappearance of colour

(achromatopsia) or

Intracranial aneurysms associated with ocular

illusional colouring (e.g., erythropsia)

manifestations are located around the circle of Willis

NEURO-OPHTHALMOLOGY

309

Intracranial aneurysms may produce complications

INTRACRANIAL SPACE-OCCUPYING

by following mechanisms:

LESIONS (ICSOLS)

1. Pressure effects. i Aneurysms of circle of Willis

These include primary and secondary brain tumours,

and internal carotid artery

(supraclenoid,

haematomas, granulomatous inflammations and

infraclenoid i.e., intracavernous, and anterior

parasitic cysts. Clinical features of the ICSOLs may

communicating artery) may produce following

be described under three heads:

pressure effects :

I. General effects of raised intracranial pressure.

Central and peripheral visual loss due to

These include headache,vomiting, papilloedema,

pressure on intracranial part of optic nerve and

drowsiness, giddiness, slowing of pulse rate and rise

chiasma.

in blood pressure.

Slowly progressive ophthalmoplegia, due to

pressure, on motor nerves in the cavernous sinus.

II. False localising signs. These occur due to the

Facial pain and paraesthesia associated with

effect of raised intracranial pressure and

corneal anaesthesia due to pressure on the

displacement or distortion of the brain tissue. False

branches of trigeminal nerve.

localising signs of ophthalmological interest are as

Horner’s syndrome due to pressure on

follows:

sympathetic fibres along the carotid artery.

1. Diplopia: It occurs due to pressure palsy of the

ii. Posterior communicating artery aneurysm

sixth nerve.

typically presents with isolated painful third nerve

2. Sluggish pupillary reflexes and unilateral

palsy.

mydriasis may occur due to pressure on the 3rd

iii. Vertebrobasilar artery aneurysms may also be

nerve.

associated with third nerve palsy.

3. Bitemporal hemianopia: It results from downward

2. Production of arteriolar venous fistula. Carotid-

pressure of the distended third ventricle on the

cavernous fistula may be produced by rupture of a

chiasma.

giant aneurysm of the intracavernous part of the

4. Homonymous hemianopia: It may result from

internal carotid artery. Pulsating exophthalmose is a

occipital herniation through the tentorium cerebelli

typical presentation of carotid-cavernous fistula.

with compression of the posterior cerebral artery.

3. Subarachnoid haemorrhage. Subarachnoid

III. Focal signs of intracranial mass lesions. These

haemorrhage is a life-threatening complication

depend upon the site of the lesion. Focal signs of

associated with sudden rupture of aneurysm of the

ophthalmological interest are as follows:

circle of Willis. It is characterized by:

1. Prefrontal tumours, particularly meningioma of

Sudden violent headache.

the olfactory groove, are associated with a

Third nerve palsy with pupillary dilatation.

pressure atrophy of the optic nerve on the side

Photophobia, signs of meningial irritation,

of lesion and papilloedema on the other side due

vomiting and unconsiousness.

to raised intracranial pressure (Foster-Kennedy

Terson syndrome refers to the combination of

syndrome).

bilateral intraocular haemorrhages (intraretinal,

2. Temporal lobe tumours. These may produce

subhyaloid and vitreous haemorrhage) and

incongruous crossed upper quadrantanopia due

subarachnoid haemorrhage due to aneurysmal

to pressure on the optic radiations. Visual

rupture.

hallucinations may occur owing to irritation of

INTRACRANIAL HAEMORRHAGES

the visuo-psychic area. Third and fifth cranial

nerves may be involved due to downward

Ophthalmic signs of intracerebral haemorrhage are

pressure. Impairment of convergence and of

tonic conjugate and dysconjugate deviations.

superior conjugate movements may occur in late

Subarachnoid haemorrhage may produce retinal

stages due to prolapse of the uncus through the

haemorrhages (especially subhyaloid haemorrhage

tentorium cerebelli into the posterior fossa, with

of the posterior pole), papilloedema, and ocular

resulting distortion of the ventral part of midbrain.

palsies.

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Comprehensive OPHTHALMOLOGY

Parietal lobe tumours. These are associated with

8. Chiasmal and pituitary tumours. These include:

crossed lower homonymous quadrantanopia due

pituitary adenomas, craniopharyngiomas and

to involvement of the upper fibres of the optic

suprasellar meningiomas. These tumours typically

radiations. Other lesions include visual and

produce chiasmal syndrome which is

auditory hallucinations, conjugate deviations of

characterised by bitemporal visual field defects,

the eyes and optokinetic nystagmus.

optic atrophy and sometimes endocrinal

Occipital lobe tumours. These may produce

disturbances.

crossed homonymous quadrantic or hemianopic

DEMYELINATING DISEASES

defect involving the fixation point. Visual agnosia

may also be associated.

These include multiple sclerosis, neuromyelitis optica

and diffuse sclerosis. Ocular involvement may occur

Mid-brain tumours. These may be associated

in all these conditions. Their salient features are as

with homonymous hemianopia due to pressure

follows:

on the optic tracts. Other signs depending upon

the site of involvement are as follows:

Multiple sclerosis

i. Tumours of the upper part produce spasmodic

It is a demyelinating disorder of unknown etiology,

contraction of the upper lid followed by ptosis

affecting women more often than men, usually in the

and loss of upward conjugate movements. In

15-50 years age group. Pathologically, the condition

about 25 percent cases, an upper motor neuron

is characterised by a patchy destruction of the myelin

facial paralysis and ipsilateral hemiplegia may

sheaths throughout the central nervous system.

also develop.

Clinical course of the condition is marked by

ii. Tumours of the intermediate level may be

remissions and relapses. In this condition, optic

associated with the following syndromes: (i)

neuritis is usually unilateral. Other ocular lesions

Weber’s syndrome. It is characterised by

include internuclear ophthalmoplegia and vestibular

ipsilateral third nerve palsy, contralateral

or cerebellar nystagmus.

hemiplegia and facial palsy of upper motor

Neuromyelitis optica (Devic’s disease)

neuron type. (ii) Benedikt’s syndrome. It is

It is characterised by bilateral optic neuritis associated

characterised by ipsilateral third nerve palsy

with ascending myelitis, entailing a progressive

associated with tremors and jerky movements

quadriplegia and anaesthesia. Unlike multiple

of the contralateral side which occur due to

sclerosis, this condition is not characterised by

involvement of the red nucleus.

remissions and is not associated with ocular palsies

Tumours of the pons. Lesions in the upper part

and nystagmus.

are characterised by ipsilateral third nerve palsy,

Diffuse sclerosis (Schilder’s disease)

contralateral hemiplegia and upper motor neuron

It typically affects children and adolescents and is

type facial palsy. While the lesions in the lower

part of the pons produce Millard-Gubler

characterised by progressive demyelination of the

entire white matter of the cerebral hemispheres.

syndrome which consists of ipsilateral sixth nerve

Ocular lesions include: optic neuritis (papillitis or

palsy, contralateral hemiplegia and ipsilateral facial

retrobulbar neuritis), cortical blindness (due to

palsy; or Foville’s syndrome is which sixth nerve

paralysis is replaced by a loss of conjugate

destruction of the visual centres and optic radiations),

movements to the same side.

ophthalmoplegia and nystagmus.

Cerebellar tumours. Those arising from the

OCULAR SIGNS IN HEAD INJURY

cerebellopontine angle produce corneal

anaesthesia due to involvement of fifth nerve,

Ocular signs related only to the intracranial damage are

early deafness and tinnitis of one side, sixth and

described here. However, direct trauma to the eyeball

seventh cranial nerve paralysis, cerebellar

and/or orbit is frequently associated with the head

symptoms such as ataxia and vertigo, marked

injury. Lesions of direct ocular trauma are described in

papilloedema and nystagmus.

the chapter on ocular injuries (pages 401-414).

NEURO-OPHTHALMOLOGY

311

A. Concussion injuries to the brain

B. Fractures of the base of skull

Associated ocular signs are as follows:

These are usually associated with subdural

1. Cranial nerve palsies. These are often seen with

haemorrhage and unconsciousness which may

fractures of the base of the skull; most common

produce the following ocular signs.

being the ipsilateral facial paralysis of the lower

motor neuron type. Extraocular muscle palsies

1. Hutchinson’s pupil. It is characterised by initial

due to involvement of sixth, third and fourth

ipsilateral miosis followed by dilatation with no light

cranial nerves may also be seen.

reflex due to raised intracranial pressure. If the

2. Optic nerve injury. It may be injured directly,

pressure rises still further, similar changes occur in

indirectly or compressed by the haemorrhage.

the contralateral pupil. Therefore, presence of bilateral

Primary optic atrophy may appear in 2-4 weeks

fixed and dilated pupils is an indication of immediate

following injury. Presence of papilloedema

cerebral decompression.

suggests haemorrhage into the nerve sheath.

3. Subconjunctival haemorrhage. It may be seen

2. Papilloedema. When it appears within 48 hours of

when fracture of the base of skull is associated

the trauma, it indicates extra or intracerebral

with fractures of the orbital roof. The

haemorrhage and is an indication for immediate

subconjunctival haemorrhage is usually more

marked in the upper quadrant and its posterior

surgical measures. While the papilloedema appearing

limit cannot be reached.

after a week of head injury is usually due to cerebral

4. Pupillary signs. These are inconsistent and thus

oedema.

not pathognomonic. However, usually pupil is

dilated on the affected side.

Strabismus and

CHAPTER

ANATOMY AND PHYSIOLOGY OF THE

Evaluation of a case

OCULAR MOTILITY SYSTEM

Pseudostrabismus

Extraocular muscles

Heterophoria

Ocular motility

Heterotropia

- Concomitant strabismus

BINOCULAR SINGLE VISION

- Incomitant strabismus

Definition

Strabismus surgery

Pre-requisites

NYSTAGMUS

Anomalies

Physiological

STRABISMUS

Sensory deprivation

Definition and classification

Motor imbalance

Medial rectus

5.5 mm

ANATOMY AND PHYSIOLOGY OF

Inferior rectus

6.5 mm

THE OCULAR MOTILITY SYSTEM

Lateral rectus

6. 9 mm

Superior rectus

7.7 mm

EXTRAOCULAR MUSCLES

The superior oblique muscle arises from the bone

A set of six extraocular muscles (4 recti and 2 obliques)

above and medial to the optic foramina. It runs

control the movements of each eye (Fig. 13.1). Rectus

forward and turns around a pulley — ‘the trochlea’

muscles are superior (SR), inferior (IR), medial (MR)

(present in the anterior part of the superomedial angle

and lateral (LR). The oblique muscles include superior

of the orbit) and is inserted in the upper and outer

(SO) and inferior (IO).

part of the sclera behind the equator (Fig. 13.3C).

Origin and insertion

The inferior oblique muscle arises by a rounded

The rectus muscles originate from a common

tendon from the orbital plate of maxilla just lateral to

tendinous ring (the annulus of Zinn), which is

the orifice of the nasolacrimal duct. It passes laterally

attached at the apex of the orbit, encircling the optic

and backward to be inserted into the lower and outer

foramina and medial part of the superior orbital fissure

part of the sclera behind the equator (Fig. 13.3C).

(Fig. 13.2). Medial rectus arises from the medial part

of the ring, superior rectus from the superior part and

Nerve supply

also the adjoining dura covering the optic nerve,

The extraocular muscles are supplied by third, fourth

inferior rectus from the inferior part and lateral rectus

and sixth cranial nerves. The third cranial nerve

from the lateral part by two heads which join in a ‘V’

form.

(oculomotor) supplies the superior, medial and inferior

All the four recti run forward around the eyeball

recti and inferior oblique muscles. The fourth cranial

and are inserted into the sclera, by flat tendons

nerve (trochlear) supplies the superior oblique and

(about 10-mm broad) at different distances from the

the sixth nerve (abducent) supplies the lateral rectus

limbus as under (Fig. 13.3):

muscle.

STRABISMUS AND NYSTAGMUS

315

Actions

The extraocular muscles rotate the eyeball around

vertical, horizontal and antero-posterior axes. Medial

and lateral rectus muscles are almost parallel to the

optical axis of the eyeball; so they have got only the

main action. While superior and inferior rectus

muscles make an angle of 23^o (Fig. 13.4) and reflected

tendons of the superior and inferior oblique muscles

of 51^o (Fig. 13.5) with the optical axis in the primary

Fig. 13.6. Action of the extraocular muscles, SR

position; so they have subsidiary actions in addition

(superior rectus); MR (medial rectus); IR (inferior

rectus); SO (superior oblique); LR (lateral rectus);

to the main action. Actions of each muscle (Fig. 13.6)

IO (inferior oblique).

are shown in Table 13.1.

Table 13.1: Actions of extraocular muscles

OCULAR MOTILITY

Muscle Primary

Secondary

Tertiary

Types of ocular movements

action

A Uniocular movements are called ‘ductions’ and

Adduction

—

include the following:

Abduction

—

1. Adduction. It is inward movement (medial rotation)

Elevation

Intorsion

Adduction

Depression

Extorsion

Adduction

along the vertical axis.

Intorsion

Depression

Abduction

2. Abduction. It is outward movement

(lateral

Extorsion

Elevation

Abduction

rotation) along the vertical axis.

3. Supraduction. It is upward movement (elevation)

Optical axis

23⁰

along the horizontal axis.

4. Infraduction. It is downward movement

(depression) along the horizontal axis.

5. Incycloduction

(intorsion). It is a rotatory

movement along the anteroposterior axis in which

superior pole of the cornea (12 O’clock point)

Superior rectus

moves medially.

6. Excycloduction

(extorsion). It is a rotatory

movement along the anteroposterior axis in which

superior pole of the cornea (12 O’clock point)

moves laterally.

Fig. 13.4. Relation of the superior and inferior rectus

B Binocular movements. These are of two types:

muscles with the optical axis in primary position.

versions and vergences.

51⁰

Optical axis

a Versions, also known as conjugate movements, are

Muscle plane

synchronous (simultaneous) symmetric movements

of both eyes in the same direction. These include:

1. Dextroversion. It is the movement of both eyes

Superior oblique

to the right. It results due to simultaneous

contraction of right lateral rectus and left medial

rectus.

2. Levoversion. It refers to movement of both eyes

to the left. It is produced by simultaneous

Fig. 13.5. Relation of the superior and inferior oblique

contraction of left lateral rectus and right medial

muscles with the optical axis in primary position.

rectus.

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Comprehensive OPHTHALMOLOGY

3. Supraversion. It is upward movement of both

Laws governing ocular movements

eyes in primary position. It results due to

1. Hering’s law of equal innervation. According to

simultaneous contraction of bilateral superior recti

it an equal and simultaneous innervation flows from

and inferior obliques.

the brain to a pair of muscles which contract

4. Infraversion. It is downward movement of both

simultaneously (yoke muscles) in different binocular

eyes in primary position. It results due to

movements, e.g.:

simultaneous contraction of bilateral inferior recti

i) During dextroversion: right lateral rectus and left

and superior obliques.

medial rectus muscles receive an equal and

5. Dextrocycloversion. It is rotational movement

simultaneous flow of innervation.

around the anteroposterior axis, in which superior

ii) During convergence, both medial recti get equal

pole of cornea of both the eyes tilts towards the

innervation.

right.

iii) During dextroelevation, right superior rectus and

6. Levocycloversion. It is just the reverse of

left inferior oblique receive equal and simultaneous

dextrocycloversion. In it superior pole of cornea

innervation.

of both the eyes tilts towards the left.

2. Sherrington’s law of reciprocal innervation.

According to it, during ocular motility increased flow

b Vergences, also called disjugate movements, are

of innervation to the contracting muscle is

synchronous and symmetric movements of both eyes

accompanied by decreased flow of innervation to the

in opposite directions e.g.:

relaxing antagonist muscle. For example, during

1. Convergence. It is simultaneous inward movement

dextroversion, an increased innervation flow to the

of both eyes which results from contraction of

right LR and left MR is accompanied by decreased

the medial recti.

flow to the right MR and left LR muscles.

2. Divergence. It is simultaneous outward movement

of both eyes produced by contraction of the

Diagnostic positions of gaze

lateral recti.

There are nine diagnostic positions of gaze (Fig. 13.7).

These include one primary, four secondary and four

Synergists, antagonists and yoke muscles

tertiary positions.

1. Synergists. It refers to the muscles having the same

1. Primary position of gaze. It is the position

primary action in the same eye; e.g., superior rectus

assumed by the eyes when fixating a distant object

and inferior oblique of the same eye act as synergistic

(straight ahead) with the erect position of head (Fig.

elevators.

13.7e).

2. Antagonists. These are the muscles having

2. Secondary positions of gaze. These are the

opposite actions in the same eye. For example, medial

positions assumed by the eyes while looking straight

and lateral recti, superior and inferior recti and superior

up, straight down, to the right and to the left (Figs.

and inferior obliques are antagonists to each other in

13.7b, d, f and h).

the same eye.

3. Tertiary positions of gaze. These describe the

3. Yoke muscles (contralateral synergists). It refers

positions assumed by the eyes when combination of

to the pair of muscles (one from each eye) which

vertical and horizontal movements occur. These

contract simultaneously during version movements.

include position of eyes in dextroelevation,

For example, right lateral rectus and left medial rectus

dextrodepression, levoelevation and levodepression

act as yoke muscles for dextroversion movements.

(Figs. 13.7a, c, g and i).

Other pairs of yoke muscles are: right MR and left LR,

4. Cardinal positions of gaze. These are the positions

right LR and left MR, right SR and left IO, right IR and

which allow examination of each of the 12 extraocular

left SO, right SO and left IR and right IO and left SR.

muscles in their main field of action. There are six

4. Contralateral antagonists. These are a pair of

cardinal positions of gaze, viz, dextroversion,

muscles (one from each eye) having opposite action;

levoversion, dextroelevation, levoelevation,

for example, right LR and left LR, right MR and

dextrodepression and levodepression (Figs. 13.7 a, c,

left MR.

d, f, g and i).

STRABISMUS AND NYSTAGMUS

317

Fig. 13.7. Diagnostic positions of gaze: primary position (e); secondary positions (b, d, f, h); tertiary positions

(a, c, g, i); cardinal positions (a, c, d, f, g, i).

SUPRANUCLEAR CONTROL OF EYE

shifts from one object to another. Thus, they are

MOVEMENTS

performed to bring the image of an object quickly on

There exists a highly accurate, still not fully elucidated,

the fovea. Though normally voluntary, saccades may

supranuclear control of eye movements which keeps

be involuntary aroused by peripheral, visual or

the two eyes yoked together so that the image of the

auditory stimuli.

object of interest is simultaneously held on both

2. Smooth pursuit eye movement system. Smooth

fovea despite movement of the perceived object or

pursuit movements are tracking movements of the

the observer’s head and/or body.

eye as they follow moving objects. These occur

Following supranuclear eye movement systems

voluntarily when the eyes track moving objects but

have been recognized:

take place involuntarily if a repetitive visual pattern

1. Saccadic system

is displayed continuously. When the velocity of the

2. Smooth pursuit system

moving object is more, the smooth pursuit movement

3. Vergence system

is replaced by small saccades (catchup saccades).

4. Vestibular system

3. Vergence movement system. Vergence movements

5. Optokinetic system

allow focussing of an object which moves away from

6. Position maintenance system

or towards the observer or when visual fixation shifts

All these systems perform specific functions and

from one object to another at a different distance.

each one is controlled by a different neural system

Vergence movements are very slow disjugate

but share the same final common path the motor

movements.

neurones that supply the extraocular muscles.

4. Vestibular eye movement system. Vestibular

1. Saccadic system. Saccades are sudden, jerky

movements are usually effective in compensating for

conjugate eye movements, that occur as the gaze

the effects of head movements in disturbing visual

318

Comprehensive OPHTHALMOLOGY

fixation. These movements operate through the

2. Reasonably clear vision in both eyes so that

vestibular system.

similar images are presented to each retina

5. Optokinetic system. The system helps to hold the

(sensory mechanism).

images of the seen world steady on the retinae during

3. Ability of visual cortex to promote binocular

sustained head rotation. This system becomes

single vision (mental process).

operative, when the vestibular reflex gets fatigued

Therefore, pathologic states disturbing any of the

after 30 seconds. It consists of a movement following

above mechanisms during the first few years of life

the moving scene, succeeded by a rapid saccade in

will hinder the development of binocular single vision

the opposite direction.

and may cause squint.

6. Position maintenance system. This system helps

Grades of binocular single vision

to maintain a specific gaze position by means of rapid

micromovements called

‘flicks’ and slow

There are three grades of binocular single vision,

micromovements called ‘drifts’. This system co-

which are best tested with the help of a synoptophore.

ordinates with other systems. Neural pathway for

Grade I — Simultaneous perception. It is the power

this system is believed to be the same as for saccades

to see two dissimilar objects simultaneously. It is

and smooth pursuits.

tested by projecting two dissimilar objects (which

can be joined or superimposed to form a complete

picture) in front of the two eyes. For example, when a

BINOCULAR SINGLE VISION

picture of a bird is projected onto the right eye and

that of a cage onto the left eye, an individual with

Definition

presence of simultaneous perception will see the bird

When a normal individual fixes his visual attention

in the cage (Fig. 13.8a).

on an object of regard, the image is formed on the

Grade II—Fusion. It consists of the power to

fovea of both the eyes separately; but the individual

superimpose two incomplete but similar images to

perceives a single image. This state is called

form one complete image (Fig. 13.8b).

binocular single vision.

The ability of the subject to continue to see one

complete picture when his eyes are made to converge

Visual development

or diverge a few degrees, gives the positive and

Binocular single vision is a conditioned reflex which

negative fusion range, respectively.

is not present since birth but is acquired during first

Grade III— Stereopsis. It consists of the ability to

6 months and is completed during first few years.

perceive the third dimension (depth perception). It

The process of its development is complex and

can be tested with stereopsis slides in synoptophore

partially understood.

Important mile stones in the visual development

(Fig. 13.8c).

are:

Anomalies of binocular vision

At birth there is no central fixation and the eyes

Anomalies of binocular vision include suppression,

move randomly.

amblyopia, abnormal retinal correspondence (ARC),

By the first month of life fixation reflex starts

confusion and diplopia.

developing and becomes established by 6 months.

By 6 months the macular stereopsis and accommo-

Suppression

dation reflex is fully developed.

It is a temporary active cortical inhibition of the image

By 6 year of age full visual acuity (6/6) is attained

of an object formed on the retina of the squinting eye.

and binocular single vision is well developed.

This phenomenon occurs only during binocular vision

Prerequisites for development of binocular

(with both eyes open). However, when the fixating eye

single vision

is covered, the squinting eye fixes (i.e., suppression

1. Straight eyes starting from the neonatal period

disappears). Tests to detect suppression include

with precise coordination for all directions of

Worth’s 4-dot test, four dioptre base out prism test, red

gaze (motor mechanism).

glass test and synoptophore test (see page 327-329).

STRABISMUS AND NYSTAGMUS

319

Fig. 13.8. Slides for testing three grades of binocular vision : A, simultaneous perception; B, fusion; C, stereopsis.

Amblyopia

Even 1-2D hypermetropic anisometropia may

Definition. Amblyopia, by definition, refers to a partial

cause amblyopia while upto

3D myopic

loss of vision in one or both eyes, in the absence of

anisometropia usually does not cause amblyopia.

any organic disease of ocular media, retina and visual

4. Isoametropic amblyopia is bilateral amblyopia

pathway.

occurring in children with bilateral uncorrected

Pathogenesis. Amblyopia is produced by certain

high refractive error.

amblyogeneic factors operating during the critical

5. Meridional amblyopia occurs in children with

period of visual development (birth to 6 years of age).

uncorrected astigmatic refractive error. It is a

The most sensitive period for development of

selective amblyopia for a specific visual meridian.

amblyopia is first six months of life and it usually

Clinical characteristics of an amblyopic eye are:

does not develop after the age of 6 years.

1. Visual acuity is reduced. Recognition acuity is

Amblyogenic factors include :

more affected than resolution acuity.

Visual

(form sense) deprivation as occurs in

2. Effect of neutral density filter. Visual acuity when

anisometropia,

tested through neutral density filter improves by

Light deprivation e.g., due to congenital cataract,

one or two lines in amblyopia and decreases in

and

patients with organic lesions.

Abnormal binocular interaction e.g., in strabismus.

3. Crowding phenomenon is present in amblyopics

Types. Depending upon the cause, amblyopia is of

i.e., visual acuity is less when tested with multiple

following types:

letter charts

(e.g., Snellen’s chart) than when

1. Strabismic amblyopia results from prolonged

tested with single charts (optotype).

uniocular suppression in children with unilateral

4. Fixation pattern may be central or eccentric.

constant squint who fixate with normal eye.

Degree of amblyopia in eccentric fixation is

2. Stimulus deprivation amblyopia

(old term:

proportionate to the distance of the eccentric

amblyopia ex anopsia) develops when one eye is

point from the fovea.

totally excluded from seeing early in life as, in

5. Colour vision is usually normal, may be affected

congenital or traumatic cataract, complete ptosis

in deep amblyopia with vision below 6/36.

and dense central corneal opacity.

Treatment of amblyopia should be started as early

3. Anisometropic amblyopia occurs in an eye

as possible (younger the child, better the prognosis).

having higher degree of refractive error than the

Occlusion therapy i.e., occlusion of the sound eye,

fellow eye. It is more common in aniso-

to force use of amblyopic eye is the main stay in the

hypermetropic than the anisomyopic children.

treatment of amblyopia. However, before the

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Comprehensive OPHTHALMOLOGY

occlusion therapy is started, it should be ensured

Mechanical restriction of ocular movements as

that:

caused by thick pterygium, symblepharon and

Opacity in the media (e.g., cataract), if any, should

thyroid ophthalmopathy.

be removed first, and

Deviation of ray of light in one eye as caused

Refractive error, if any, should be fully corrected.

by decentred spectacles.

Simplified schedule for occlusion therapy depending

Anisometropia i.e., disparity of image size between

up on the age is as below:

two eyes as occurs in acquired high anisometropia

Upto 2 years, the occlusion should be done in

(e.g., uniocular aphakia with spectacle correction).

2:1, i.e.,

2 days in sound eye and one day in

Types. Binocular diplopia may be crossed or

amblyopic eye.

uncrossed.

At the age of 3 years, 3:1,

Uncrossed diplopia. In uncrossed (harmonious)

At the age of 4 years, 4:1,

diplopia the false image is on the same side as

At the age of 5 years, 5:1, and

deviation. It occurs in convergent squint.

After the age of 6 years, 6:1

Crossed diplopia. In crossed

(unharmonious)

Duration of occlusion should be until the visual

diplopia the false image is seen on the opposite

acuity develops fully, or there is no further

side. It occurs in divergent squint.

improvement of vision for 3 months.

Uniocular diplopia. Though not an anomaly of

Abnormal retinal correspondence (ARC)

binocular vision, but it will not be out of place to

In a state of normal binocular single vision, there exists

describe uniocular diplopia along with binocular

a precise physiological relationship between the

diplopia.

corresponding points of the two retinae. Thus, the

In uniocular diplopia an object appears double from

foveae of two eyes act as corresponding points and

the affected eye even when the normal eye is closed.

have the same visual direction. This adjustment is

Causes of uniocular diplopia are:

called normal retinal correspondence (NRC). When

Subluxated clear lens (pupillary area is partially

squint develops, patient may experience either

phakic and partially aphakic).

diplopia or confusion. To avoid these, sometimes

Subluxated intraocular lens

(pupillary area is

(especially in children with small degree of esotropia),

partially aphakic and partially pseudophakic).

there occurs an active cortical adjustment in the

directional values of the two retinae. In this state

Double pupil due to congenital anomaly, or large

fovea of the normal eye and an extrafoveal point on

peripheral iridectomy or iridodialysis.

the retina of the squinting eye acquire a common

Incipient cataract. Usually polyopia i.e., multiple

visual direction (become corresponding points). This

images may be seen due to multiple water clefts

condition is called abnormal retinal correspondence

within the lens.

(ARC) and the child gets a crude type of binocular

Keratoconus. Diplopia occurs due to changed

single vision.

refractive power of the cornea in different parts.

Tests to detect abnormal retinal correspondence

Treatment of diplopia. Treat the causative disease.

include Worth’s four-dot test, titmus stereo test,

Temporary relief from annoying diplopia can be

Bagolini striated glass tests, after image tests and

obtained by occluding the affected eye.

synoptophore tests (see page 327-329).

Diplopia

STRABISMUS

Binocular diplopia occurs due to formation of image

on dissimilar points of the two retinae (see page 331)

Definition

Causes of binocular diplopia are:

Paralysis or paresis of the extraocular muscles

Normally visual axis of the two eyes are parallel to

(commonest cause)

each other in the ‘primary position of gaze’ and this

Displacement of one eye ball as occurs in space

alignment is maintained in all positions of gaze.

occupying lesion in the orbit, and fractures of the

A misalignment of the visual axes of the two eyes

orbital wall,

is called squint or strabismus.

STRABISMUS AND NYSTAGMUS

321

Classification of strabismus

iii Non-specific type (exophoria which does not vary

Broadly, strabismus can be classified as below:

significantly in degree for any distance).

Apparent squint or pseudostrabismus.

3. Hyperphoria. It is a tendency to deviate upwards,

II.

Latent squint (Heterophoria)

while hypophoria is a tendency to deviate

III. Manifest squint (Heterotropia)

downwards. However, in practice it is customary to

1. Concomitant squint

use the term right or left hyperphoria depending on

2. Incomitant squint.

the eye which remains up as compared to the other.

4. Cyclophoria. It is a tendency to rotate around the

PSEUDOSTRABISMUS

anteroposterior axis. When the 12 O’clock meridian

In pseudostrabismus (apparent squint), the visual

of cornea rotates nasally, it is called incyclophoria

axes are in fact parallel, but the eyes seem to have a

and when it rotates temporally it is called

squint:

excyclophoria.

1. Pseudoesotropia or apparent convergent squint

may be associated with a prominent epicanthal

Etiology

fold

(which covers the normally visible nasal

A. Anatomical factors

aspect of the globe and gives a false impression

Anatomical factors responsible for development of

of esotropia) and negative angle kappa.

heterophoria include:

2. Pseudoexotropia or apparent divergent squint

1. Orbital asymmetry.

may be associated with hypertelorism, a condition

of wide separation of the two eyes, and positive

2. Abnormal interpupillary distance (IPD). A wide

angle kappa.

IPD is associated with exophoria and small with

esophoria.

HETEROPHORIA

3. Faulty insertion of extraocular muscle.

Heterophoria also known as ‘latent strabismus’, is a

4. A mild degree of extraocular muscle weakness.

condition in which the tendency of the eyes to deviate

5. Anomalous central distribution of the tonic

is kept latent by fusion. Therefore, when the influence

innervation of the two eyes.

of fusion is removed the visual axis of one eye

6. Anatomical variation in the position of the macula

deviates away. Orthophoria is a condition of perfect

in relation to the optical axis of the eye.

alignment of the two eyes which is maintained even

after the removal of influence of fusion. However,

B. Physiological factors

orthophoria is a theoretical ideal. Practically a small

1. Age. Esophoria is more common in younger age

amount of heterophoria is of universal occurrence

group as compared to exophoria which is more

and is known as ‘physiological heterophoria’.

often seen in elderly.

2. Role of accommodation. Increased accommo-

Types of heterophoria

dation is associated with esophoria (as seen in

1. Esophoria. It is a tendency to converge. It may

hypermetropes and individuals doing excessive

be:

near work) and decreased accommodation with

i Convergence excess type (esophoria greater for

exophoria (as seen in simple myopes).

near than distance).

3. Role of convergence. Excessive use of

ii Divergence weakness type (esophoria greater for

convergence may cause esophoria (as occurs in

distance than near).

bilateral congenital myopes) while decreased use

iii Non-specific type

(esophoria which does not

of convergence is often associated with exophoria

vary significantly in degree for any distance).

(as seen in presbyopes).

2. Exophoria. It is a tendency to diverge. It may be:

i Convergence weakness type (exophoria greater

4. Dissociation factor such as prolonged constant

for near than distance).

use of one eye may result in exophoria (as occurs

ii Divergence excess type

(exophoria greater on

in individuals using uniocular microscope and

distant fixation than the near).

watch makers using uniocular magnifying glass).

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Comprehensive OPHTHALMOLOGY

Factors predisposing to decompensation

2. Cover-uncover test. It tells about the presence and

Inadequacy of fusional reserve,

type of heterophoria. To perform it, one eye is covered

General debility and lowered vitality,

with an occluder and the other is made to fix an object.

Psychosis, neurosis, and mental stress,

In the presence of heterophoria, the eye under cover

Precision of job, and

will deviate. After a few seconds the cover is quickly

Advancing age.

removed and the movement of the eye (which was

under cover) is observed. Direction of movement of

Symptoms

the eyeball tells the type of heterophoria (e.g., the

Depending upon the symptoms heterophoria can be

eye will move outward in the presence of esophoria)

divided into compensated and decompensated.

and the speed of movement tells whether recovery is

Compensated heterophoria. It is associated with no

slow or rapid.

subjective symptoms. Compensation of heterophoria

3. Prism cover test. (see page 327).

depends upon the reserve neuro-muscular power to

4. Maddox rod test. Patient is asked to fix on a point

overcome the muscular imbalance and individual’s

light in the centre of Maddox tangent scale (Fig. 13.9)

desire for maintenance of binocular vision.

at a distance of 6 metres. A Maddox rod (which

Decompensated heterophoria. It is associated with

consists of many glass rods of red colour set together

multiple symptoms which may be grouped as under:

in a metallic disc) (Fig. 13.10) is placed in front of one

1. Symptoms of muscular fatigue. These result due

eye with axis of the rod parallel to the axis of deviation

to continuous use of the reserve neuromuscular

(Fig. 13.11).

power. These include:

Headache and eyeache after prolonged use of

eyes, which is relieved when the eyes are closed.

Difficulty in changing the focus from near to

distant objects of fixation or vice-versa.

Photophobia due to muscular fatigue is not

relieved by using dark glasses, but relieved by

closing one eye.

2. Symptoms of failure to maintain binocular single

vision are:

Blurring or crowding of words while reading;

Intermittent diplopia due to temporary manifest

deviation under conditions of fatigue; and

Fig. 13.9. Maddox tangent scale.

Intermittent squint (without diplopia) which is

usually noticed by the patient’s close relations or

friends.

3. Symptoms of defective postural sensations cause

problems in judging distances and positions

especially of the moving objects. This difficulty

may be experienced by cricketers, tennis players

and pilots during landing.

Examination of a case of heterophoria

It should include the following tests:

1. Testing for vision and refractive error. It is most

important, because a refractive error may be

responsible for the symptoms of the patient or for the

deviation itself. Preferably, refraction should be

performed under full cycloplegia, especially in

children.

Fig. 13.10. Maddox rod.

STRABISMUS AND NYSTAGMUS

323

Fig. 13.11. Maddox rod test for horizontal (A) and vertical (B) heterophorias.

The Maddox rod converts the point light image

is asked to tell the number on the horizontal line which

into a line. Thus, the patient will see a point light with

the vertical white arrow is pointing (this will give

one eye and a red line with the other. Due to dissimilar

amount of horizontal phoria) and the number on the

images of the two eyes, fusion is broken and

vertical line at which the red arrow is pointing (this

heterophoria becomes manifest. The number on

will measure the vertical phoria). The cyclophoria is

Maddox tangent scale where the red line falls will be

measured by asking the patient to align the red arrow

the amount of heterophoria in degrees. In the absence

with the horizontal line of numbers (Fig. 13.13).

of Maddox tangent scale, the dissociation between

6. Measurement of convergence and accom-

the point light and red line is measured by the

modation. It is important in planning the management

superimposition of the two images by means of prisms

of heterophorias. Near point of convergence (NPC)

placed in front of one eye with apex towards the

can be measured with the help of a RAF rule or the

phoria.

Livingstone binocular gauge. The normal NPC is

5. Maddox wing test. Maddox wing is an instrument

considered to be around 70 mm.

(Fig. 13.12) by which the amount of phoria for near

Near point of accommodation (NPA) should be

(at a distance of 33 cm) can be measured. It is also measured after the NPC. NPA can be measured with

based on the basic principle of dissociation of fusion the help of a RAF or Prince’s rule. Normal NPA varies

by dissimilar objects.

with the age of patient (see page 41).

The instrument is designed in such a way that,

7. Measurement of fusional reserve. It can be done

through its two slits, right eye sees a vertical white

with the help of a synoptophore or prism bar. The

arrow and a horizontal red arrow and the left eye sees

normal values of fusional reserve are as follows:

a vertical and a horizontal line of numbers. The patient

Vertical fusional reserve: 1.5°-2.5°

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Comprehensive OPHTHALMOLOGY

Fig. 13.12. Maddox wing.

Fig. 13.13. Maddox wing test.

Horizontal negative fusional reserve (abduction

CONCOMITANT STRABISMUS

range): 3°-5°

It is a type of manifest squint in which the amount of

deviation in the squinting eye remains constant

Horizontal positive fusional reserve (adduction

(unaltered) in all the directions of gaze; and there is

range) : 20°-40°

no associated limitation of ocular movements.

Treatment

Etiology

It is indicated in decompensated heterophoria (i.e.,

symptomatic cases).

It is not clearly defined. The causative factors differ

in individual cases. As we know, the binocular vision

1. Correction of refractive error when detected is

and coordination of ocular movements are not present

most important.

since birth but are acquired in the early childhood.

2. Orthoptic treatment. It is indicated in patients with

The process starts by the age of 3-6 months and is

heterophoria without refractive error and in those

completed up to 5-6 years. Therefore, any obstacle to

where heterophoria and/or symptoms are not

the development of these processes may result in

corrected by glasses. Aim of orthoptic treatment is

concomitant squint. These obstacles can be arranged

to improve convergence insufficiency and the fusional

into three groups, namely: sensory, motor and central.

reserve. Orthoptic exercises can be done with

1. Sensory obstacles. These are the factors which

synoptophore. Simple exercises to be carried out at

hinder the formation of a clear image in one eye. These

home should also be taught to the patient.

include:

3. Prescription of prism in glasses. It may be tried in

Refractive errors,

selected cases of hyperphoria and in troublesome

Prolonged use of incorrect spectacles,

cases of esophoria and exophoria. Prism is prescribed

Anisometropia,

with apex towards the direction of phoria to correct

Corneal opacities,

only half or at the most two-thirds of heterophoria.

Lenticular opacities,

4. Surgical treatment. It is undertaken in patients

Diseases of macula (e.g., central chorioretinitis),

with marked symptoms which are not relieved by other

measures. Aim of the surgical management is to

Optic atrophy, and

strengthen the weak muscle or weaken the strong

Obstruction in the pupillary area due to congenital

muscle.

ptosis.

STRABISMUS AND NYSTAGMUS

325

2. Motor obstacles. These factors hinder the

Types of concomitant squint

maintenance of the two eyes in the correct positional

Three common types of concomitant squint are :

relationship in primary gaze and/or during different

1. Convergent squint (esotropia),

ocular movements. A few such factors are:

2. Divergent squint (exotropia), and

Congenital abnormalities of the shape and size of

3. Vertical squint (hypertropia).

the orbit,

Abnormalities of extraocular muscles such as

CONVERGENT SQUINT

faulty insertion, faulty innervation and mild

Concomitant convergent squint or esotropia denotes

paresis,

inward deviation of one eye (Fig. 13.14). It can be

Abnormalities of accommodation, convergence

unilateral (the same eye always deviates inwards

and AC/A ratio.

and the second normal eye takes fixation) or

3. Central obstacles. These may be in the form of:

alternating (either of the eyes deviates inwards and

Deficient development of fusion faculty, or

the other eye takes up fixation, alternately).

Abnormalities of cortical control of ocular

movements as occurs in mental trauma, and

hyperexcitability of the central nervous system

during teething.

Clinical features of concomitant strabismus (in

general)

The cardinal features of different clinico-etiological

types of concomitant strabismus are described

separately. However, the clinical features of

concomitant strabismus (in general) are as below :

1. Ocular deviation. Characteristics of ocular

deviation are:

Fig. 13.14. Concomitant squint, (right esotropia).

Unilateral

(monocular squint) or alternating

(alternate squint).

Clinico-etiological types

Inward deviation (esotropia) or outward deviation

Depending upon the clinico-etiological features

(exotropia) or vertical deviation (hypertropia).

convergent concomitant squint can be further

Primary deviation (of squinting eye) is equal to

classified into following types:

secondary deviation

(deviation of normal eye

1. Accommodative esotropia. It occurs due to

under cover when patient fixes with squinting

overaction of convergence associated with

eye).

accommodation reflex. It is of three types: refractive,

Ocular deviation is equal in all the directions of

non-refractive and mixed.

gaze.

i. Refractive accommodative esotropia: It usually

2. Ocular movements are not limited in any direction.

develops at the age of

2 to

3 years and is

3. Refractive error may or may not be associated.

associated with high hypermetropia (+4 to +7 D).

4. Suppression and amblyopia may develop as

Mostly it is for near and distance (marginally

sensory adaptation to strabismus. Suppression may

more for near) and fully correctable by use of

be monocular (in monocular squint) and alternating

spectacles.

(in alternating strabismus). Amblyopia develops in

ii. Non-refractive accommodative esotropia: It is

monocular strabismus only and is responsible for

caused by abnormally AC/A

(accommodative

poor visual acuity.

convergence/accommodation) ratio. This may

5. A-V patterns may be observed in horizontal

occur even in patients with no refractive error.

strabismus. When A-V patterns are associated, the

Esotropia is greater for near than that for distance

horizontal concomitant strabismus becomes vertically

(minimal or no deviation for distance). It is fully

incomitant (see page 334).

corrected by adding +3 DS for near vision.

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Comprehensive OPHTHALMOLOGY

iii. Mixed accommodative esotropia: It is caused by

Clinico-etiological types

combination of hypermetropia and high AC/A

It can be classified into following clinicoetiological

ratio. Esotropia for distance is corrected by

types:

correction of hypermetropia; and the residual

1. Congenital exotropia. It is rare and almost always

esotropia for near is corrected by an addition of

present at birth. It is characterised by a fairly large

+3 DS lens.

angle of squint, usually alternate with homonymous

fixation in lateral gaze, and no amblyopia.

2. Non-accommodative esotropias. This group

2. Primary exotropia. It is a common variety of

includes all those primary esodeviations in which

exodeviation (unilateral or alternating). It presents

amount of deviation is not affected by the state of

with variable features. It may be of:

accommodation. It includes:

Convergence insufficiency type (exotropia greater

Essential infantile esotropia. It usually presents

for near than distance),

at 1-2 months of age. However, it may be detected

Divergence excess (exotropia greater for distance

shortly after birth or any time within the first 6

than near) or

months of life. Previously, it was known as

Basic non-specific type (exotropia equal for near

congenital esotropia. It is characterised by fairly

and distance).

large angle of squint (> 30^o), alternate fixation in

It usually starts as intermittent exotropia at the

primary gaze and crossed fixation in lateral gaze.

age of 2 years. It is associated with normal fusion

ii.

Essential acquired or late onset esotropia. It is

and no amblyopia. Stereopsis is usually absent.

a common variety of concomitant convergent

Precipitating factors include bright light, fatigue, ill-

squint. It typically occurs during first few years

health and day-dreaming. If not treated in time it

of life. It is of three types:

decompensates to become constant exotropia (Fig.

Basic type. In it the deviation is usually

13.15).

equal at distance and near.

3. Secondary (sensory deprivation) exotropia. It is a

Convergence excess type. In it the deviation

constant unilateral deviation which results from long-

is large for near and small or no deviation for

standing monocular lesions (in adults), associated

distance.

with low vision in the affected eye. Common causes

Divergence insufficiency type. It is

include: traumatic cataract, corneal opacity, optic

characterized by a greater deviation for

atrophy, anisometropic amblyopia, retinal detachment

distance than near.

and organic macular lesions.

4. Consecutive exotropia. It is a constant unilateral

Secondary esotropia. It includes:

exotropia which results either due to surgical over-

Sensory deprivation esotropia. It results from

correction of esotropia, or spontaneous conversion

monocular lesions (in childhood) which either

of small degree esotropia with amblyopia into

prevent the development of normal binocular

exotropia.

vision or interfere with its maintenance. Examples

of such lesions are: cataract, severe congenital

ptosis, aphakia, anisometropia, optic atrophy,

retinoblastoma, central chorioretinitis and

so on.

ii.

Consecutive esotropia. It results from surgical

overcorrection of exotropia.

DIVERGENT SQUINT

Concomitant divergent squint (exotropia) is

characterised by outward deviation of one eye while

the other eye fixates.

Fig. 13.15. A patient with primary exotropia.

STRABISMUS AND NYSTAGMUS

327

EVALUATION OF A CASE OF CONCOMITANT

STRABISMUS

I. History

A meticulous history is very important. It should

include: age of onset, duration, mode of onset (sudden

or gradual), any illness preceding squint (fever,

trauma, infections, etc.), intermittent or constant,

unilateral or alternating, history of diplopia, family

history of squint, history of head tilt or turn and so

on.

II. Examination

1. Inspection. Large degree squint (convergent

or divergent) is obvious on inspection.

2. Ocular movements. Both uniocular as well as

binocular movements should be tested in all the

Fig. 13.16. Direct cover test depicting left exotropia.

cardinal positions of gaze.

3. Pupillary reactions. These may be abnormal in

7. Estimation of angle of deviation

patients with secondary deviations due to diseases

i. Hirschberg corneal reflex test. It is a rough but

of retina and optic nerve.

handy method to estimate the angle of manifest

4. Media and fundus examination. It may reveal

squint. In it the patient is asked to fixate at point

associated disease of ocular media, retina or optic

light held at a distance of 33 cm and the deviation

nerve.

of the corneal light reflex from the centre of pupil is

5. Testing of vision and refractive error. It is most

noted in the squinting eye. Roughly, the angle of

important, because a refractive error may be

squint is 15^o and 45^o when the corneal light reflex

responsible for the symptoms of the patient or for the

falls on the border of pupil and limbus, respectively

deviation itself. Preferably, refraction should be

(Fig. 13.17).

performed under full cycloplegia, especially in

ii. The prism and cover test (prism bar cover test

children.

i.e., PBCT). Prisms of increasing strength with apex

6. Cover tests

towards the deviation are placed in front of one eye

i. Direct cover test

(Fig.

13.16). It confirms the

and the patient is asked to fixate an object with the

presence of manifest squint. To perform it, the

other. The cover-uncover test is performed till there

patient is asked to fixate on a point light. Then, the

is no recovery movement of the eye under cover.

normal looking eye is covered while observing the

This will tell the amount of deviation in prism

movement of the uncovered eye. In the presence of

dioptres. Both heterophoria as well as heterotropia

squint the uncovered eye will move in opposite

can be measured by this test.

direction to take fixation, while in apparent squint

iii. Krimsky corneal reflex test. In this test the

there will be no movement. This test should be

patient is asked to fixate on a point light and prisms

performed for near texation (i.e., at 33 cm) distance

of increasing power (with apex towards the direction

tixation(i.e., at 6 metres).

of manifest squint) are placed in front of the normal

ii. Alternate cover test. It reveals whether the squint

fixating eye till the corneal light reflex is centred in

is unilateral or alternate and also differentiates

the squinting eye. The power of prism required to

concomitant squint from paralytic squint

(where

centre the light reflex in the squinting eye equals the

secondary deviation is greater than primary).

amount of squint in prism dioptres.

328

Comprehensive OPHTHALMOLOGY

0×5° 15×5° 30×5° 45×5°

70×5°

Fig. 13.17. Hirschberg corneal reflex test.

iv. Measurement of deviation with synoptophore.

All types of heterophorias and heterotropias (both

objective and subjective angle of squint) can be

measured accurately with it. In addition, many other

Fig. 13.18. Worth’s four-dot test.

tests can also be performed with this instrument (for

details see pages 329).

When he sees three green lights and two red

8. Tests for grade of binocular vision and sensory

lights, alternately, it indicates presence of

functions. Normal binocular single vision consists

alternating suppression.

of three grades. Sensory anomalies include

If the patient sees five lights (2 red and 3 green),

disturbances of binocular vision, eccentric fixation,

he has diplopia (Fig. 13.18E).

suppression, amblyopia, abnormal retinal

ii. Test for fixation. It can be tested with the help

correspondence and diplopia. A few common tests

of a visuoscope or fixation star of the

for sensory functions are as follows:

ophthalmoscope. Patient is asked to cover one eye

i. Worth’s four-dot test.: For this test patient wears

and fix the star with the other eye. Fixation may be

goggles with red lens in front of the right and green

centric (normal on the fovea) or eccentric (which

lens in front of the left eye and views a box with

may be unsteady, parafoveal, macular, paramacular,

four lights - one red, two green and one white (Fig.

or peripheral (Fig. 13.19).

13.18).

iii. After-image test. In this test the right fovea is

Interpretation.:

stimulated with a vertical and left with a horizontal

If the patient sees all the four lights in the

bright light and the patient is asked to draw the

absence of manifest squint, he has normal

position of after-images.

binocular single vision (Fig. 13.18A).

Interpretation:

In abnormal retinal correspondence (ARC) patient

A patient with normal retinal correspondence will

sees four lights even in the presence of a manifest

draw a cross (Fig. 13.20A).

squint.

An esotropic patient with abnormal retinal

If the patient sees only three green lights, he has

correspondence (ARC) will draw vertical image to

right suppression (Fig. 13.18D).

the left of horizontal (Fig. 13.20B).

When the patient sees only two red lights, it

An exotropic patient with ARC will draw vertical

indicates left suppression (Fig. 13.18C).

image to the right of horizontal (Fig. 13.20C).

STRABISMUS AND NYSTAGMUS

329

are equal. In ARC, objective angle is greater than

the subjective angle and the difference between

these is called the angle of anomaly. When the

angle of anomaly is equal to the objective angle,

the ARC is harmonious. In unharmonious ARC

Central Fixation

angle of anomaly is smaller than the objective

Parafoveal

angle.

Macular

Paramacular

(v) Neutral density filter test. In this test, visual

Peripheral

acuity is measured without and with neutral

density filter placed in front of the eye. In cases

with functional amblyopia visual acuity slightly

improves while in organic amblyopia it is markedly

reduced when seen through the filter.

Fig. 13.19. Types of fixation.

TREATMENT OF CONCOMITANT STRABISMUS

iv. Sensory function tests with synoptophore.

Goals of treatment. These are to achieve good

Synoptophore (major amblyoscope) consists of two

cosmetic correction, to improve visual acuity and to

tubes, having a right-angled bend, mounted on a

maintain binocular single vision. However, many a

base (Fig. 13.21). Each tube contains a light source

time it is not possible to achieve all the goals in every

for illumination of slides and a slide carrier at the

case.

outer end, a reflecting mirror at the right-angled

Treatment modalities. These include the following:

bend and an eyepiece of +6.5 D at the inner end

1. Spectacles with full correction of refractive error

(Fig. 13.22). The two tubes can be moved separately

or together by means of knobs around a semicircular

should be prescribed in every case. It will improve

scale. Synoptophore is used for many diagnostic

the visual acuity and at times may correct the

and therapeutic indications in orthoptics.

squint partially or completely

(as in

Synoptophore tests for sensory functions

accommodative squint).

include:

2. Occlusion therapy. It is indicated in the presence

Estimation of grades of binocular vision

of amblyopia. After correcting the refractive error,

(page 318).

the normal eye is occluded and the patient is

Detection of normal/abnormal retinal correspon-

advised to use the squinting eye. Regular follow-

dence

(ARC). It is done by determining the

ups are done in squint clinic. Occlusion helps to

subjective and objective angles of the squint. In

improve the vision in children below the age of

normal retinal correspondence, these two angles

10 years.

Fig. 13.20. After-image test: A, normal retinal correspondence; B, esotropia with ARC; C, exotropia with ARC.

330

Comprehensive OPHTHALMOLOGY

Fig. 13.21. Synoptophore.

Fig. 13.22. Optical principle of synoptophore.

Preoperative orthoptic exercises. These are given

INCOMITANT SQUINT

after the correction of amblyopia to overcome

It is a type of heterotropia (manifest squint) in which

suppression.

the amount of deviation varies in different directions

Squint surgery. It is required in most of the cases

of gaze. It includes following conditions:

to correct the deviation. However, it should always

1. Paralytic squint,

be instituted after the correction of refractive

2. ‘A’ and ‘V’ pattern heterotropias,

error, treatment of amblyopia and orthoptic

3. Restrictive squint.

exercises.

PARALYTIC STRABISMUS

Basic principles of squint surgery. These are

to weaken the strong muscle by recession

It refers to ocular deviation resulting from complete

(shifting the insertion posteriorly) or to

or incomplete paralysis of one or more extraocular

strengthen the weak muscle by resection

muscles.

(shortening the muscle).

Etiology

Type and amount of muscle surgery. It depends

The lesions may be neurogenic, myogenic or at the

upon the type and angle of squint, age of

level of neuromuscular junction.

patient, duration of the squint and the visual

status. Therefore, degree of correction versus

I. Neurogenic lesions

amount of extraocular muscle manipulation

1. Congenital. Hypoplasia or absence of nucleus is

required cannot be mathematically determined.

a known cause of third and sixth cranial nerve

However, roughly 1 mm resection of medial

palsies. Birth injuries may mimic congenital

rectus (MR) will correct about 1°-1.5° and 1

lesions.

mm recession will correct about 2°-2.5°. While

1 mm resection and recession of lateral rectus

2. Inflammatory lesions. These may be in the form

(LR) muscle will correct 1°-2°. The maximum

of encephalitis, meningitis, neurosyphilis or

limit allowed for MR resection is 8 mm and

peripheral neuritis (commonly viral). Nerve trunks

recession is 5.5 mm. The corresponding figures

may also be involved in the infectious lesions of

for LR muscle are

10 mm and 8 mm,

cavernous sinus and orbit.

respectively.

3. Neoplastic lesions. These include brain tumours

Postoperative orthoptic exercises. These are

involving nuclei, nerve roots or intracranial part

required to improve fusional range and maintain

of the nerves; and intraorbital tumours involving

binocular single vision.

peripheral parts of the nerves.

STRABISMUS AND NYSTAGMUS

331

Vascular lesions. These are known in patients

with hypertension, diabetes mellitus and

atherosclerosis. These may be in the form of

haemorrhage, thrombosis, embolism, aneurysms

or vascular occlusions. Cerebrovascular accidents

are more common in elderly people.

Traumatic lesions. These include head injury

and direct or indirect trauma to the nerve trunks.

Toxic lesions. These include carbon monoxide

poisoning, effects of diphtheria toxins (rarely),

alcoholic and lead neuropathy.

Demyelinating lesions. Ocular palsy may occur

in multiple sclerosis and diffuse sclerosis.

II.

Myogenic lesions

Congenital lesions. These include absence,

hypoplasia, malinsertion, weakness and musculo-

facial anomalies.

Traumatic lesions. These may be in the form of

Fig. 13.23. Diplopia.

laceration, disinsertion, haemorrhage into the

muscle substance or sheath and incarceration of

2. Confusion. It occurs due to formation of image of

muscles in fractures of the orbital walls.

two different objects on the corresponding points

Inflammatory lesions. Myositis is usually viral in

of two retinae.

origin and may occur in influenza, measles and

3. Nausea and vertigo. These result from diplopia

other viral fevers.

and confusion.

Myopathies. These include thyroid myopathy,

4. Ocular deviation. It is of sudden onset.

carcinomatous myopathy and that associated with

Signs

certain drugs. Progressive external ophthalmo-

1. Primary deviation. It is deviation of the affected

plegia is a bilateral myopathy of extraocular

eye and is away from the action of paralysed

muscles; which may be sporadic or inherited as

muscle, e.g., if lateral rectus is paralysed the eye

an autosomal dominant disorder.

is converged.

2. Secondary deviation. It is deviation of the normal

III. Neuromuscular junction lesion

eye seen under cover, when the patient is made

It includes myasthenia gravis. The disease is

to fix with the squinting eye. It is greater than the

characterised primarily by fatigue of muscle groups,

primary deviation. This is due to the fact that the

usually starting with the small extraocular muscles,

strong impulse of innervation required to enable

before involving other large muscles.

the eye with paralysed muscle to fix is also

Clinical features

transmitted to the yoke muscle of the sound eye

resulting in a greater amount of deviation. This is

Symptoms

based on Hering’s law of equal innervation of

1. Diplopia. It is the main symptom of paralytic

yoke muscles.

squint. It is more marked towards the action of

3. Restriction of ocular movement. It occurs in the

paralysed muscle. It may be crossed (in divergent

direction of the action of paralysed muscles

squint) or uncrossed (in convergent squint). It

4. Compensatory head posture. It is adopted to

may be horizontal, vertical or oblique depending

avoid diplopia and confusion. Head is turned

on the muscle paralysed. Diplopia occurs due to

towards the direction of action of the paralysed

formation of image on dissimilar points of the two

muscle, e.g., if the right lateral rectus is paralysed,

retinae (Fig. 13.23).

patient will keep the head turned towards right.

332

Comprehensive OPHTHALMOLOGY

5. False projection or orientation. It is due to

increased innervational impulse conveyed to the

paralysed muscle. It can be demonstrated by

asking the patient to close the sound eye and

then to fix an object placed on the side of

paralysed muscle. Patient will locate it further

away in the same direction. For example, a patient

with paralysis of right lateral rectus will point

towards right more than the object actually is.

Pathological sequelae of an extraocular muscle

palsy

In all cases of extraocular muscle palsy, certain

sequelae take place after some time. These occur more

in paralysis due to lesions of the nerves than the

lesions of muscles. These include:

1. Overaction of the contralateral synergistic muscle.

2. Contracture of the direct antagonist muscle.

3. Secondary inhibitional palsy of the contralateral

antagonist muscle.

For example, in paralysis of the right lateral rectus

muscle there occurs (Fig 13.24):

Overaction of the left medial rectus,

Contracture of the right medial rectus and

Inhibitional palsy of the left lateral rectus muscle.

Clinical varieties of ocular palsies

1. Isolated muscle paralysis. Lateral rectus and

Fig. 13.25. A patient with third cranial nerve paralysis

superior oblique are the most common muscles to be

showing: A, ptosis; B, divergent squint.

paralysed singly, as they have separate nerve supply.

Isolated paralysis of the remaining four muscles is

Ptosis due to paralysis of the LPS muscle.

less common, except in congenital lesions.

Deviation. Eyeball is turned down, out and slightly

2. Paralysis of the third cranial nerve. It is of

intorted due to actions of the lateral rectus and

common occurrence. It may be congenital or acquired.

superior oblique muscles.

Clinical features of third nerve palsy (Fig. 13.25 A

Ocular movements are restricted in all the

and B) include:

directions except outward.

Pupil is fixed and dilated due to paralysis of the

sphincter pupillae muscle.

Accommodation is completely lost due to

paralysis of the ciliary muscle.

Crossed diplopia is elicited on raising the eyelid.

Head posture may be changed if pupillary area

remains uncovered.

3. Double elevator palsy. It is a congenital condition

caused by third nerve nuclear lesion. It is

characterised by paresis of the superior rectus and

Fig. 13.24. Pathological sequelae of the right lateral

rectus muscle paralysis.

the inferior oblique muscle of the involved eye.

STRABISMUS AND NYSTAGMUS

333

4. Total ophthalmoplegia. In this condition all

required for a case of paralytic squint are :

extraocular muscles including LPS and intraocular

Diplopia charting. It is indicated in patients

muscles, viz., sphincter pupillae, and ciliary muscle

complaining of confusion or double vision. In it

are paralysed. It results from combined paralysis of

patient is asked to wear red and green diplopia

third, fourth and sixth cranial nerves. It is a common

charting glasses. Red glass being in front of the

feature of orbital apex syndrome and cavernous sinus

right eye and green in front of the left. Then in

thrombosis.

a semi-dark room, he is shown a fine linear light

5. External ophthalmoplegia. In this condition, all

from a distance of 4 ft. and asked to comment on

extraocular muscles are paralysed, sparing the

the images in primary position and in other

intraocular muscles. It results from lesions at the level

positions of gaze. Patient tells about the position

of motor nuclei sparing the Edinger-Westphal

and the separation of the two images in different

nucleus.

fields. Fig. 13.26 shows diplopia charting in a

6. Internuclear ophthalmoplegia. In this condition

patient with right lateral rectus palsy.

there is lesion of the medial longitudinal bundle. It is

Hess screen test. Hess screen/Lees screen (Fig.

the pathway by which various ocular motor nuclei

13.27) test tells about the paralysed muscles and

are linked. Internuclear ophthalmoplegia is

the pathological sequelae of the paralysis, viz.,

characterised by: defective action of medial rectus

overaction, contracture and secondary inhibitional

on the side of lesion, horizontal nystagmus of the

palsy.

opposite eye and defective convergence.

The two charts are compared. The smaller chart

Investigations of a case of paralytic squint

belongs to the eye with paretic muscle and the

larger to the eye with overacting muscle (Fig.

A. Evaluation for squint

13.28).

Every case of squint should be evaluated utilising

Field of binocular fixation. It should be tested

the tests described on page 327-329. Additional tests

in patients with paralytic squint where applicable,

i.e., if patient has some field of single vision. This

test is performed on the perimeter using a central

chin rest.

Fig. 13.26. Diplopia chart of a patient with

right lateral rectus palsy.

Fig. 13.27. Hees screen.

334

Comprehensive OPHTHALMOLOGY

2. Conservative measures. These include: wait and

watch for self-improvement to occur for a period

of 6 months, vitamin B-complex as neurotonic;

and systemic steroids for non-specific

inflammations.

3. Treatment of annoying diplopia. It includes use

of occluder on the affected eye, with intermittent

use of both eyes with changed headposture to

avoid suppression amblyopia.

Fig. 13.28. Hess chart in right lateral rectus palsy.

4. Surgical treatment. It should be carried out in

case the recovery does not occur in 6 months.

4. Forced duction test (FDT). It is performed to

differentiate between the incomitant squint due

Aim of treatment is to provide a comfortable field

to paralysis of extraocular muscle and that due to

of binocular fixation, i.e., in central field and lower

mechanical restriction of the ocular movements.

quadrants. The principles of surgical treatment

FDT is positive (resistance encountered during

involve strengthening of the paralysed muscle

passive rotation) in cases of incomitant squint

by resection; and weakening of the overacting

due to mechanical restriction and negative in

muscle by recession.

cases of extraocular muscle palsy.

‘A’ AND ‘V’ PATTERN HETEROTROPIA

B. Investigations to find out the cause of paralysis

The terms ‘A’ or ‘V’ pattern squint are labelled when

These include orbital ultrasonography, orbital and

skull computerised tomography scanning and

the amount of deviation in squinting eye varies by

neurological investigations.

more than 10° and 15°, respectively, between upward

and downward gaze.

Paralytic vs. non-paralytic squint

‘A’ and ‘V’ esotropia. In ‘A’ esotropia the amount of

Differences between paralytic and non-paralytic

deviation increases in upward gaze and decreases in

squint are depicted in Table 13.2.

downward gaze. The reverse occurs in ‘V’ esotropia.

Management

‘A’ and ‘V’ exotropia. In ‘A’ exotropia the amount

1. Treatment of the cause. An exhaustive

of deviation decreases in upward gaze and increases

investigative work-up should be done to find out

in downward gaze. The reverse occurs in ‘V’

the cause and, if possible, treat it.

exotropia.

Table 13.2. Differences between paralytic and non-paralytic squint

Features

Paralytic squint

Non-paralytic squint

1. Onset

Usually sudden

Usually slow

2. Diplopia

Usually present

Usually absent

3. Ocular movements

Limited in the direction of action of paralysed muscle.

Full

4. False projection

It is positive i.e., patient cannot correctly locate the

False projection is

object in space when asked to see in the direction

negative

of paralysed muscle in early stages.

5. Head posture

A particular head posture depending upon the muscle Normal

paralysed may be present.

6. Nausea and vertigo

Present

Absent

7. Secondary deviation

More than the primary deviation

Equal to primary deviation.

8. In old cases patho-

Present

Absent

logical sequelae in the

muscles

STRABISMUS AND NYSTAGMUS

335

Clinical presentations

STRABISMUS SURGERY

A and V pattern heterophoria essentially refer to

Surgical techniques

vertically incomitant horizontal strabismus. Thus, the

1. Muscle weakening procedures include recession,

horizontally comitant esotropias and exotropias

marginal myotomy and myectomy.

(described on page 324-326) may be associated with

2. Muscle strengthening procedures are resection,

A or V patterns.

tucking and advancement.

RESTRICTIVE SQUINT

3. Procedures that change direction of muscle

In restrictive squint, the extraocular muscle is not

action. These include (a) vertical transposition of

horizontal recti to correct ‘A’ and ‘V’ patterns (b)

paralysed but its movement is mechanically restricted.

Restrictive squints are characterized by a smaller

posterior fixation suture

(Faden operation) to

ocular deviation in primary position in proportion to

correct dissociated vertical deviation; and

(c)

the limitation of movement and a positive forced

transplantation of muscles in paralytic squints.

duction test (i.e., a restriction is encountered on

Steps of recession (Fig. 13.29)

passive rotation) (see page 334).

Muscle is exposed by reflecting a flap of overlying

Common causes of restrictive squint are :

Duane’s retraction syndrome,

conjunctiva and Tenon’s capsule.

Brown’s superior oblique tendon sheath

Two vicryl sutures are passed through the outer

syndrome,

quarters of the muscle tendon near the insertion.

Strabismus fixus,

The muscle tendon is disinserted from the sclera

Dysthyroid ophthalmopathy (see page 390), and

with the help of tenotomy scissors.

Incarceration of extraocular muscle in blow-out

The amount of recession is measured with the

fracture of the orbit (see page 397).

callipers and marked on the sclera.

The muscle tendon is sutured with the sclera at

1. Duane’s retraction syndrome

the marked site posterior to original insertion.

It is a congenital ocular motility defect occurring due

Conjunctival flap is sutured back.

to fibrous tightening of lateral or medial or both rectus

muscles. Its features are:

Limitation of abduction

(type I) or adduction

(type II) or both (type III).

Retraction of the globe and narrowing of the

palpebral fissure on attempted adduction.

Eye in the primary position may be orthotropic,

esotropic or exotropic.

2. Brown’s superior oblique tendon sheath

syndrome

It is congenital ocular motility defect due to fibrous

tightening of the superior oblique tendon. It is

characterized by limitation of elevation of the eye in

adduction (normal elevation in abduction), usually

straight eyes in primary position and positive forced

duction test on attempts to elevate eye in adduction.

3. Strabismus fixus

It is a rare condition characterised by bilateral fixation

of eyes in convergent position due to fibrous

tightening of the medial recti.

Fig. 13.29. Technique of recession.

336

Comprehensive OPHTHALMOLOGY

Steps of resection (Fig. 13.30)

1. It may be pendular or jerk nystagmus. In pendular

1. Muscle is exposed as for recession and the

nystagmus movements are of equal velocity in

amount to be resected is measured with callipers

each direction. It may be horizontal, vertical or

and marked.

rotatory. In jerk nystagmus, the movements have

2. Two absorbable sutures are passed through the

a slow component in one direction and a fast

outer quarters of the muscles at the marked site.

component in the other direction. The direction

3. The muscle tendon is disinserted from the sclera

of jerk nystagmus is defined by direction of the

and the portion of the muscle anterior to sutures

fast component (phase). It may be right, left, up,

is excised.

down or rotatory.

4. The muscle stump is sutured with the sclera at

2. Nystagmus movements may be rapid or slow.

the original insertion site.

3. The movements may be fine or coarse.

5. Conjunctival flap is sutured back.

4. Nystagmus may be latent or manifest.

Types of nystagmus

NYSTAGMUS

I. Physiological nystagmus

It is defined as regular and rhythmic to-and-fro

1. Optokinetic nystagmus. It is a physiological jerk

involuntary oscillatory movements of the eyes.

nystagmus induced by presenting to gaze the

Etiology

objects moving serially in one direction, such as

It occurs due to disturbance of the factors

strips of a spinning optokinetic drum. The eyes

responsible for maintaining normal ocular posture.

will follow a fixed strip momentarily and then jerk

These include disorders of sensory visual pathway,

back to reposition centrally to fix up a new strip.

vestibular apparatus, semicircular canals, mid-brain

Similar condition occurs while looking at outside

and cerebellum.

things from a moving train.

2. End-point nystagmus. It is a fine jerk horizontal

Features of nystagmus

nystagmus seen in normal persons on extreme

It may be characterised by any of the following

right or left gaze.

features:

3. Physiological vestibular nystagmus. It is a jerk

nystagmus which can be elicited by stimulating

the tympanic membrane with hot or cold water. It

forms the basis of caloric test. If cold water is

poured into right ear the patient develops left jerk

nystagmus (rapid phase towards left), while the

reverse happens with warm water, i.e., patient

develops right jerk nystagmus. It can be

remembered by the mnemonic ‘COWS’ (Cold-

Opposite, Warm-Same).

II. Sensory deprivation (ocular) nystagmus. It may

occur in following forms:

1. Congenital pendular (ocular) nystagmus. It is a

horizontal slow pendular nystagmus usually

associated with sensory deprivation due to

reduced central visual acuity. Its common causes

are congenital cataract, congenital toxoplas-mosis,

macular hypoplasia, aniridia, albinism, optic nerve

hypoplasia and Leber’s congenital amaurosis.

2. Acquired ocular nystagmus. It occurs in

Fig. 13.30. Technique of resection.

monocular adults when they develop decreased

STRABISMUS AND NYSTAGMUS

337

visual acuity in the only seeing eye. It is a

pendular nystagmus.

nystagmus which shows fluctuations in

3. Miner’s nystagmus. It is a rapid rotatory type of

amplitude and direction. It may occur due to

nystagmus which occurs in coal mine workers. It

vascular or demyelinating brain stem-

cerebellar lesions.

probably results from fixation difficulties in the

6. Gaze-paretic nystagmus. It is a slow horizontal

dim illumination.

jerk nystagmus due to upper brain stem

III. Motor imbalance nystagmus

dysfunction.

Congenital jerk nystagmus. It is a hereditary

7. Convergence retraction nystagmus. It is a jerk

nystagmus of unknown etiology which persists

nystagmus with bilateral fast component towards

throughout life. It is bilateral, horizontal jerk

the medial side. It is associated with retraction of

nystagmus with rapid phase towards the lateral

the globe in convergence.

side. It is not present during sleep.

8. See-saw nystagmus. In it, one eye rises up and

Latent nystagmus. It is not present when both

intorts, while the other shifts down and extorts.

eyes are open. It appears when one eye is covered.

It is usually associated with upper brain stem

It is a jerk nystagmus with rapid phase towards

lesions.

the uncovered eye.

9. Nystagmus blockage syndrome. It is a rare

Spasmus nutans. It is characterised by fine

condition in which sudden esotropia develops in

pendular horizontal nystagmus associated with

infancy to dampen the horizontal nystagmus.

head nodding and abnormal head posture. It

appears in infancy and self-resolves by the age

NYSTAGMOID MOVEMENTS

of 3 years.

There are ocular movements which mimic nystagmus.

Peripheral vestibular nystagmus. It occurs due

These include:

to diseases of the eighth nerve or vestibular end

1. Ocular flutter occurs due to interruption of

organ. The nystagmus is jerky, fine, rapid and

cerebellar connection to brain stem. It is characterized

horizontal-rotatory.

by horizontal oscillation and inability to fixate after

Central vestibular nystagmus. It may be of the

change of gaze.

following types:

2. Opsoclonus refers to combined horizontal, vertical

(a) Upbeat nystagmus. In primary position of

and/or torsional oscillations associated with

gaze, the fast component is upward. It is

myoclonic movement of face, arms and legs. It is seen

usually seen in lesions of central tegmentum

in patients with encephalitis.

of brain stem.

(b) Down beat nystagmus. In primary position

3. Superior oblique myokymia is characterized by

monocular, rapid, intermittent, torsional vertical

of gaze the fast component is downward. It

movements (which are best seen on slit-lamp

is usually associated with posterior fossa

examination).

diseases and is typical of compression at

the level of foramen magnum. It is a common

4. Ocular bobbing refers to rapid downward

feature of cerebellar lesions and Arnold

deviation of the eyes with slow updrift. It occurs due

Chiari syndrome.

to pontine dysfunctions.

Diseases of the

CHA1

Eyelids

APPLIED ANATOMY

ANOMALIES IN THE POSITION OF

Gross anatomy

LASHES AND LID MARGIN

Structure

Trichiasis

Glands of eyelid

Entropion

Blood supply

Ectropion

Nerve supply

Symblepharon

Ankyloblepharon

CONGENITAL ANOMALIES

Blepharophimosis

OEDEMA OF LIDS

Lagophthalmos

INFLAMMATORY DISORDERS

Blepharospasm

Blepharitis

Ptosis

Chalazion

TUMOURS

Hordeolum internum

Molluscum contagiosum

INJURIES

The lid margin. It is about 2-mm broad and is divided

APPLIED ANATOMY

into two parts by the punctum. The medial, lacrimal

portion is rounded and devoid of lashes or glands.

GROSS ANATOMY

The eyelids are mobile tissue curtains placed in front

of the eyeballs (Fig. 14.1). These act as shutters

protecting the eyes from injuries and excessive light.

These also perform an important function of spreading

the tear film over the cornea and conjunctiva and

also help in drainage of tears by lacrimal pump system.

Parts of eyelid. Each eyelid is divided by a horizontal

furrow (sulcus) into an orbital and tarsal part.

Position of lids. When the eye is open, the upper lid

covers about one-sixth of the cornea and the lower

Fig. 14.1. Gross anatomy of the eyelid.

lid just touches the limbus.

Canthi. The two lids meet each other at medial and

The lateral, ciliary portion consists of a rounded

lateral angles (or outer and inner canthi). The medial

anterior border, a sharp posterior border (placed

canthus is about 2 mm higher than the lateral canthus.

against the globe) and an intermarginal strip (between

Palpebral aperture. It is the elliptical space between

the two borders). The grey line (which marks junction

the upper and the lower lid. When the eyes are open

of skin and conjunctiva) divides the intermarginal strip

it measures about 10-11 mm vertically in the centre

into an anterior strip bearing 2-3 rows of lashes and a

and about 28-30 mm horizontally.

posterior strip on which openings of meibomian

340

Comprehensive OPHTHALMOLOGY

glands are arranged in a row. The splitting of the

palpebrae superioris muscle (LPS). It arises from

eyelids when required in operations is done at the

the apex of the orbit and is inserted by three parts

level of grey line.

on the skin of lid, anterior surface of the tarsal plate

and conjunctiva of superior fornix. It raises the

STRUCTURE

upper lid. It is supplied by a branch of oculomotor

Each eyelid consists (from anterior to posterior) of

nerve.

the following layers (Fig. 14.2):

4. Submuscular areolar tissue. It is a layer of loose

1. The skin. It is elastic having a fine texture and is

connective tissue. The nerves and vessels lie in this

the thinnest in the body.

layer. Therefore, to anaesthetise lids, injection is

2. The subcutaneous areolar tissue. It is very loose

given in this plane.

and contains no fat. It is thus readily distended by

5. Fibrous layer. It is the framework of the lids and

oedema or blood.

consists of two parts: the central tarsal plate and the

3. The layer of striated muscle. It consists of

peripheral septum orbitale (Fig. 14.3).

orbicularis muscle which forms an oval sheet across

i. Tarsal plate. There are two plates of dense

the eyelids. It comprises three portions: the orbital,

connective tissue, one for each lid, which give

palpebral and lacrimal. It closes the eyelids and is

shape and firmness to the lids. The upper and

supplied by zygomatic branch of the facial nerve.

lower tarsal plates join with each other at medial

Therefore, in paralysis of facial nerve there occurs

and lateral canthi; and are attached to the orbital

lagophthalmos which may be complicated by

margins through medial and lateral palpebral

exposure keratitis.

ligaments. In the substance of the tarsal plates lie

In addition, the upper lid also contains levator

meibomian glands in parallel rows.

Fig. 14.2. Structure of the upper eyelid.

DISEASES OF THE EYELIDS

341

Fig. 14.3. Tarsal plates and septum orbitale.

ii. Septum orbitale (palpebral fascia). It is a thin

3. Glands of Moll. These are modified sweat glands

membrane of connective tissue attached centrally

situated near the hair follicle. They open into the

to the tarsal plates and peripherally to periosteum

hair follicles or into the ducts of Zeis glands.

of the orbital margin. It is perforated by nerves,

They do not open directly onto the skin surface

vessels and levator palpebrae superioris (LPS)

as elsewhere.

muscle, which enter the lids from the orbit.

4. Accessory lacrimal glands of Wolfring. These

6. Layer of non-striated muscle fibres. It consists

are present near the upper border of the tarsal

of the palpebral muscle of Muller which lies deep to

plate.

the septum orbitale in both the lids. In the upper lid

it arises from the fibres of LPS muscle and in the

BLOOD SUPPLY

lower lid from prolongation of the inferior rectus

The arteries of the lids (medial and lateral palpebral)

muscle; and is inserted on the peripheral margins of

form marginal arterial arcades which lie in the

the tarsal plate. It is supplied by sympathetic fibres.

submuscular plane in front of the tarsal plate, 2 mm

7. Conjunctiva. The part which lines the lids is

away from the lid margin, in each lid. In the upper lid

called palpebral conjunctiva. It consists of three

another arcade (superior arterial arcade) is formed

parts: marginal, tarsal and orbital.

which lies near the upper border of the tarsal plate.

Branches go forward and backward from these arches

GLANDS OF EYELIDS (Fig. 14.4)

to supply various structures.

1. Meibomian glands. These are also known as

Veins. These are arranged in two plexuses: a post-

tarsal glands and are present in the stroma of

tarsal which drains into ophthalmic veins and a pre-

tarsal plate arranged vertically. They are about

tarsal opening into subcutaneous veins.

30-40 in the upper lid and about 20-30 in the

lower lid. They are modified sebaceous glands.

Lymphatics. These are also arranged in two sets: the

Their ducts open at the lid margin. Their secretion

pre-tarsal and the post-tarsal. Those from lateral half

constitutes the oily layer of tear film.

of the lids drain into preauricular lymph nodes and

2. Glands of Zeis. These are also sebaceous glands

those from the medial half of the eyelids drain into

which open into the follicles of eyelashes.

submandibular lymph nodes.

342

Comprehensive OPHTHALMOLOGY

Fig. 14.4. Glands of eyelids.

2. Congenital coloboma. It is a rare condition

NERVES OF LIDS

characterised by a full thickness triangular gap in the

Motor nerves are facial (which supplies orbicularis

tissues of the lids (Fig. 14.5). The anomaly usually

muscle), oculomotor (which supplies LPS muscle) and

occurs near the nasal side and involves the upper lid

sympathetic fibres (which supply the Muller’s

more frequently than the lower lid. Treatment consists

muscle). Sensory nerve supply is derived from

of plastic repair of the defect.

branches of the trigeminal nerve.

3. Epicanthus. It is a semicircular fold of skin which

covers the medial canthus. It is a bilateral condition

and may disappear with the development of nose. It

CONGENITAL ANOMALIES

is a normal facial feature in Mongolian races. It is the

most common congenital anomaly of the lids.

1. Congenital ptosis. It is a common congenital Treatment consists of plastic repair of the deformity.

anomaly. It is described in detail in the section of

4. Distichiasis. Congenital distichiasis is a rare

ptosis on page 356.

anomaly in which an extra row of cilia occupies the

DISEASES OF THE EYELIDS

343

6. Microblepharon. In this condition, eyelids are

abnormally small. It is usually associated with

microphthalmos or anophthalmos. Occasionally the

lids may be very small or virtually absent and the

condition is called ablepharon.

OEDEMA OF THE EYELIDS

Owing to the looseness of the tissues, oedema of the

lids is of common occurrence. It may be classified as

inflammatory, solid and passive oedema.

I Inflammatory oedema. It is seen in the following

Fig. 14.5. Congenital coloboma upper eyelid.

conditions.

1. Inflammations of the lid itself, which include

position of Meibomian glands which open into their

dermatitis, stye, hordeolum internum, insect bites,

follicles as ordinary sebaceous glands. These cilia

cellulitis and lid abscess.

are usually directed backwards and when rubbing

2. Inflammations of the conjunctiva, such as acute

the cornea, should be electroepilated or cryoepilated.

Acquired distichiasis (metaplastic lashes) occurs

purulent, membranous and pseudo-membranous

conjunctivitis.

when due to metaplasia and differentiation, the

meibomian glands are transformed into hair follicles.

3. Inflammations of the lacrimal sac, i.e., acute

The most important cause is late stage of cicatrizing

dacryocystitis and lacrimal abscess.

conjunctivitis associated with chemical injury,

4. Inflammations of the lacrimal gland, i.e., acute

Stevens-Johnson syndrome and ocular cicatricial

dacryoadenitis.

pemphigoid.

5. Cryptophthalmos. It is a very rare anomaly in which

5. Inflammations of the eyeball, such as acute

lids fail to develop and the skin passes continuously

iridocyclitis, endophthalmitis and panophthal-

from the eyebrow to the cheek hiding the eyeball

mitis.

(Fig. 14.6).

6. Inflammations of the orbit, which include orbital

cellulitis, orbital abscess and pseudo-tumour.

7. Inflammations of the paranasal sinuses, e.g.,

maxillary sinusitis.

II. Solid oedema of the lids. It is chronic thickening

of the lids, which usually follows recurrent attacks of

erysipelas. It resembles oedema of the lids but is

harder in consistency.

III. Passive oedema of the lids. It may occur due to

local or general causes.

1. Local causes are: cavernous sinus thrombosis,

head injury and angioneurotic oedema.

2. General causes are congestive heart failure, renal

Fig. 14.6. Cryptophthalmos.

failure, hypoproteinaemia and severe anaemia.

344

Comprehensive OPHTHALMOLOGY

Treatment. General measures include improvement

INFLAMMATORY DISORDERS OF

of health and balanced diet. Associated seborrhoea

THE EYELIDS

of the scalp should be adequately treated. Local

measures include removal of scales from the lid margin

BLEPHARITIS

with the help of lukewarm solution of 3 percent soda

bicarb or baby shampoo and frequent application of

It is a subacute or chronic inflammation of the lid

combined antibiotic and steroid eye ointment at the

margins. It is an extremely common disease which

lid margin.

can be divided into following clinical types:

Seborrhoeic or squamous blepharitis,

Ulcerative blepharitis

Staphylococcal or ulcerative blepharitis,

Etiology. It is a chronic staphylococcal infection of

Mixed staphylococcal with seborrhoeic blepharitis,

the lid margin usually caused by coagulase positive

Posterior blepharitis or meibomitis, and

strains. The disorder usually starts in childhood and

Parasitic blepharitis.

may continue throughout life. Chronic conjunctivitis

Seborrhoeic or squamous blepharitis

and dacryocystitis may act as predisposing factors.

Etiology. It is usually associated with seborrhoea of

Symptoms. These include chronic irritation, itching,

scalp (dandruff). Some constitutional and metabolic

mild lacrimation, gluing of cilia, and photophobia. The

factors play a part in its etiology. In it, glands of Zeis

symptoms are characteristically worse in the morning.

secrete abnormal excessive neutral lipids which are

Signs (Fig. 14.8). Yellow crusts are seen at the root of

split by Corynebacterium acne into irritating free fatty

cilia which glue them together. Small ulcers, which

acids.

bleed easily, are seen on removing the crusts. In

Symptoms. Patients usually complain of deposition

between the crusts, the anterior lid margin may show

of whitish material at the lid margin associated with

dilated blood vessels (rosettes).

mild discomfort, irritation, occasional watering and a

Complications and sequelae. These are seen in long-

history of falling of eyelashes.

standing (non-treated) cases and include chronic

Signs. Accumulation of white dandruff-like scales are

conjunctivitis, madarosis (sparseness or absence of

seen on the lid margin, among the lashes (Fig. 14.7).

lashes), trichiasis, poliosis (greying of lashes), tylosis

On removing these scales underlying surface is found

(thickening of lid margin) and eversion of the punctum

to be hyperaemic (no ulcers). The lashes fall out

leading to epiphora. Eczema of the skin and ectropion

easily but are usually replaced quickly without

may develop due to prolonged watering. Recurrent

distortion. In long-standing cases lid margin is

styes is a very common complication.

thickened and the sharp posterior border tends to be

Treatment. It should be treated promptly to avoid

rounded leading to epiphora.

complication and sequelae. Crusts should be removed

Fig. 14.7. Seborrhoeic blepharitis.

Fig. 14.8. Ulcerative blepharitis.

DISEASES OF THE EYELIDS

345

after softening and hot compresses with solution of

Phthiriasis palpebram to that due to crab-louse, very

3 percent soda bicarb. Antibiotic ointment should be

rarely to the head-louse. In addition to features of

applied at the lid margin, immediately after removal of

chronic blepharitis, it is characterized by presence of

crusts, at least twice daily. Antibiotic eyedrops should

nits at the lid margin and at roots of eyelashes

be instilled 3-4 times in a day. Avoid rubbing of the

(Fig. 14.10).

eyes or fingering of the lids. Oral antibiotics such as

Treatment consists of mechanical removal of the nits

erythromycin or tetracyclines may be useful. Oral

with forceps followed by rubbing of antibiotic

anti-inflammatory drugs like ibuprofen help in

ointment on lid margins, and delousing of the patient,

reducing the inflammation.

other family members, clothing and bedding.

Posterior blepharitis (Meibomitis)

EXTERNAL HORDEOLUM (STYE)

1. Chronic meibomitis is a meibomian gland

It is an acute suppurative inflammation of gland of

dysfunction, seen more commonly in middle-aged

the Zeis or Moll.

persons with acne rosacea and seborrhoeic dermatitis.

Etiology

It is characterized by white frothy (foam-like) secretion

on the eyelid margins and canthi (meibomian

1. Predisposing factors. It is more common in

children and young adults (though no age is bar)

seborrhoea). On eversion of the eyelids, vertical

and in patients with eye strain due to muscle

yellowish streaks shining through the conjunctiva

imbalance or refractive errors. Habitual rubbing

are seen. At the lid margin, openings of the meibomian

of the eyes or fingering of the lids and nose,

glands become prominent with thick secretions

chronic blepharitis and diabetes mellitus are

(Fig. 14.9).

usually associated with recurrent styes. Metabolic

2. Acute meibomitis occurs mostly due to

factors, chronic debility, excessive intake of

staphylococcal infection.

carbohydrates and alcohol also act as predisposing

Treatment of meibomitis consists of expression of

factors.

the glands by repeated vertical lid massage, followed

2. Causative organism commonly involved is

by rubbing of antibiotic-steroid ointment at the lid

Staphylococcus aureus.

margin. Antibiotic eyedrops should be instilled 3-4

times. Systemic tetracyclines for 6-12 weeks remain

Symptoms

the mainstay of treatment of posterior blepharitis.

These include acute pain associated with swelling of

Erythromycin may be used where tetracyclines are

lid, mild watering and photophobia.

contraindicated.

Signs

Parasitic blepharitis

Stage of cellulitis is characterised by localised,

Blepharitis acrica refers to a chronic blepharitis

hard, red, tender swelling at the lid margin asso-

associated with Demodex folliculorum infection and

ciated with marked oedema (Fig. 14.11).

Fig. 14.9. Chronic meibomitis.

Fig. 14.10. Phthiriasis palpebram.

346

Comprehensive OPHTHALMOLOGY

Clinical picture

Patients usually present with a painless swelling in

the lid and a feeling of mild heaviness. Examination

usually reveals small, firm to hard, non-tender swelling

present slightly away from the lid margin (Fig. 14.12).

It usually points on the conjunctival side, as a red,

purple or grey area, seen on everting the lid. Rarely,

the main bulk of the swelling project on the skin side.

Occasionally, it may present as a reddish-grey nodule

on the intermarginal strip (marginal chalazion).

Frequently, multiple chalazia may be seen involving

Fig. 14.11. Hordeolum externum (stye) upper eyelid.

one or more eyelids.

Stage of abscess formation is characterised by a

visible pus point on the lid margin in relation to

Clinical course and complications

the affected cilia.

Complete spontaneous resolution may occur

Usually there is one stye, but occasionally, these

rarely.

may be multiple.

Often it slowly increases in size and becomes

very large. A large chalazion of the upper lid may

Treatment

press on the cornea and cause blurred vision

Hot compresses 2-3 times a day are very useful in

from induced astigmatism. A large chalazion of

cellulitis stage. When the pus point is formed it may

the lower lid may rarely cause eversion of the

be evacuated by epilating the involved cilia. Surgical

incision is required rarely for a large abscess.

punctum or even ectropion and epiphora.

Antibiotic eyedrops (3-4 times a day) and eye

Occasionally, it may burst on the conjunctival

ointment (at bed time) should be applied to control

side, forming a fungating mass of granulation

infection. Anti-inflammatory and analgesics relieve

tissue.

pain and reduce oedema. Systemic antibiotics may

Secondary infection leads to formation of

be used for early control of infection. In recurrent

hordeolum internum.

styes, try to find out and treat the associated

Calcification may occur, though very rarely.

predisposing condition.

Malignant change into meibomian gland

CHALAZION

carcinoma may be seen occasionally in elderly

It is also called a tarsal or meibomian cyst. It is a

people.

chronic non-infective granulomatous inflammation of

the meibomian gland.

Etiology

1. Predisposing factors are similar to hordeolum

externum.

2. Pathogenesis. Usually, first there occurs mild grade

infection of the meibomian gland by organisms of

very low virulence. As a result, there occurs

proliferation of the epithelium and infiltration of the

walls of the ducts, which are blocked.

Consequently, there occurs retention of secretions

(sebum) in the gland, causing its enlargement. The

pent-up secretions (fatty in nature) act like an

irritant and excite non-infective granulomatous

inflammation of the meibomian gland.

Fig. 14.12. Chalazion upper eye lid.

DISEASES OF THE EYELIDS

347

Treatment

INTERNAL HORDEOLUM

It is a suppurative inflammation of the meibomian

Conservative treatment. In a small, soft and recent

gland associated with blockage of the duct.

chalazion, self-resolution may be helped by

conservative treatment in the form of hot

Etiology. It may occur as primary staphylococcal

fomentation, topical antibiotic eyedrops and oral

infection of the meibomian gland or due to secondary

anti-inflammatory drugs.

infection in a chalazion (infected chalazion).

Intralesional injection of long-acting steroid

Clinical picture. Symptoms are similar to hordeolum

(triamcinolone) is reported to cause resolution in

externum, except that pain is more intense, due to the

about 50 percent cases, especially in small and

swelling being embedded deeply in the dense fibrous

soft chalazia. So, such a trial is worthwhile before

tissue. On examination, it can be differentiated from

the surgical intervention.

hordeolum externum by the fact that in it, the point of

Incision and curettage

(Fig.

14.13) is the

maximum tenderness and swelling is away from the

conventional and effective treatment for chalazion.

lid margin and that pus usually points on the tarsal

Surface anaesthesia is obtained by instillation of

conjunctiva (seen as yellowish area on everting the

xylocaine drops in the eye and the lid in the

lid) and not on the root of cilia (Fig. 14.14). Sometimes,

region of the chalazion is infiltrated with 2 per-

pus point may be seen at the opening of involved

cent xylocaine solution. An incision is made with

meibomian gland or rarely on the skin.

a sharp blade, which should be vertical on the

Treatment. It is similar to hordeolum externum, except

conjunctival side

(to avoid injury to other

that, when the pus is formed, it should be drained by

meibomian ducts) and horizontal on skin side (to

a vertical incision from the tarsal conjunctiva.

have an invisible scar). The contents are curetted

MOLLUSCUM CONTAGIOSUM

out with the help of a chalazion scoop. To avoid

It is a viral infection of the lids, commonly affecting

recurrence, its cavity should be cauterised with

carbolic acid. An antibiotic ointment is instilled

children. It is caused by a large poxvirus. Its typical

and eye padded for about 12 hours. To decrease

lesions are multiple, pale, waxy, umbilicated swellings

postoperative discomfort and prevent infection,

scattered over the skin near the lid margin (Fig. 14.15).

antibiotic eyedrops, hot fomentation and oral

These may be complicated by chronic follicular

anti-inflammatory and analgesics may be given

conjunctivitis and superficial keratitis.

for 3-4 days.

Treatment. The skin lesions should be incised and

Diathermy. A marginal chalazion is better treated

the interior cauterised with tincture of iodine or pure

by diathermy.

carbolic acid.

Fig. 14.13. Incision and curettage of chalazion

from the conjunctival side.

Fig. 14.14. Hordrolum internum lower eyelid.

348

Comprehensive OPHTHALMOLOGY

Fig. 14.15. Molluscum contagiosum of the lids.

ANOMALIES IN THE POSITION OF

THE LASHES AND LID MARGIN

TRICHIASIS

It refers to inward misdirection of cilia (which rub

against the eyeball) with normal position of the lid

margin (Fig. 14.16A). The inward turning of lashes

along with the lid margin (seen in entropion) is called

pseudotrichiasis.

Etiology. Common causes of trichiasis are : cicatrising

trachoma, ulcerative blepharitis, healed membranous

Fig. 14.16. Trichiasis; A, Diagramatic depiction;

conjunctivitis, hordeolum externum, mechanical

B, Clinical photograph.

injuries, burns, and operative scar on the lid margin.

Symptoms. These include foreign body sensation

Electrolysis: It is a method of destroying the lash

and photophobia. Patient may feel troublesome

follicle by electric current. In this technique,

irritation, pain and lacrimation.

infiltration anaesthesia is given to the lid and a

current of 2 mA is passed for 10 seconds through

Signs. Examination reveals one or more misdirected

a fine needle inserted into the lash root. The

cilia touching the cornea. Reflex blepharospasm and

loosened cilia with destroyed follicles are then

photophobia occur when cornea is abraded.

removed with epilation forceps.

Conjunctiva may be congested. Signs of causative

Cryoepilation: It is also an effective method of

disease viz. trachoma, blepharitis etc. may be present.

treating trichiasis. After infiltration anaesthesia, the

Complications. These include recurrent corneal

cryoprobe (-20 °C) is applied for 20-25 seconds to

abrasions, superficial corneal opacities, corneal

the external lid margin. Its main disadvantage is

vascularisation (Fig. 14.16B) and non-healing corneal

depigmentation of the skin.

ulcer.

Surgical correction: When many cilia are

Treatment. A few misdirected cilia may be treated by

misdirected operative treatment similar to cicatricial

any of the following methods:

entropion should be employed.

1. Epilation (mechanical removal with forceps): It is

ENTROPION

a temporary method, as recurrence occurs within

3-4 weeks.

It is inturning of the lid margin.

DISEASES OF THE EYELIDS

349

Types

1. Congenital entropion. It is a rare condition seen

since birth. It may be associated with micro-

phthalmos.

2. Cicatricial entropion (Fig. 14.17). It is a common

variety usually involving the upper lid. It is caused

by cicatricial contraction of the palpebral conjunctiva,

with or without associated distortion of the tarsal

plate.

Common causes are trachoma, membranous

conjunctivitis, chemical burns, pemphigus and

Stevens-Johnson syndrome.

3. Spastic entropion. It occurs due to spasm of the

Fig. 14.17. Cicatricial entropion.

orbicularis muscle in patients with chronic irritative

corneal conditions or after tight ocular bandaging. It

commonly occurs in old people and usually involves

the lower lid.

4. Senile (involutional) entropion. It is a common

variety and only affects the lower lid in elderly people

(Fig. 14.18). The etiological factors which contribute

for its development are : (i) weakening or dehiscence

of capsulopalpebral fascia (lower lid retractor);

(ii) degeneration of palpebral connective tissue

separating the orbicularis muscle fibres and thus

allowing pre-septal fibres to override the pretarsal

fibres; and (iii) horizontal laxity of the lid.

Fig. 14.18. Senile entropion lower eyelid.

5. Mechanical entropion. It occurs due to lack of

support provided by the globe to the lids. Therefore,

it may occur in patients with phthisis bulbi,

2. Spastic entropion. (i) Treat the cause of blepharo-

enophthalmos and after enucleation or evisceration

spasm e.g. remove the bandage (if applied) or treat

operation.

the associated condition of cornea. (ii) Adhesive

plaster pull on the lower lid may help during acute

Clinical picture

spasm. (iii) Injection of botulinum toxins in the

Symptoms occur due to rubbing of cilia against the

orbicularis muscle is advocated to relieve the spasm.

cornea and conjunctiva and are thus similar to

(iv) Surgical treatment similar to involutional (senile)

trichiasis. These include foreign body sensation,

entropion may be undertaken if the spasm is not

irritation, lacrimation and photophobia.

relieved by above methods.

Signs. On examination, lid margin is found inturned.

3. Cicatricial entropion. It is treated by a plastic

Depending upon the degree of inturning it can be

operation, which is based on any of the following

divided into three grades. In grade I, only the

basic principles : (i) Altering the direction of lashes,

posterior lid border is inrolled. Grade II entropion,

(ii) Transplanting the lashes, (iii) Straightening the

includes inturning up to the inter-marginal strip while

distorted tarsus.

in grade III the whole lid margin including the anterior

Surgical techniques employed for correcting

border is inturned.

cicatricial entropion are as follows:

i. Resection of skin and muscle. It is the simplest

Complications. These are similar to trichiasis.

operation employed to correct mild degree of

Treatment

entropion. In this operation an elliptical strip of

1. Congenital entropion requires plastic reconstruc-

skin and orbicularis muscle is resected 3 mm

tion of the lid crease.

away from the lid margin.

350

Comprehensive OPHTHALMOLOGY

ii. Resection of skin, muscle and tarsus: It corrects

margin. Mattress sutures are then passed from

moderate degree of entropion associated with

the upper cut end of the tarsal plate to emerge on

atrophic tarsus. In this operation, in addition to

the skin 1 mm above the lid margin. When sutures

the elliptical resection of skin and muscle, a

are tied the entropion is corrected by transposition

wedge of tarsal plate is also removed (Fig. 14.19A).

of tarsoconjunctival wedge.

iii. Modified Burrow’s operation. It is performed

4. Senile entropion. Commonly used surgical

from the conjunctival side after everting the lid.

techniques are as follows:

A horizontal incision is made along the whole

i. Modified Wheeler’s operation: A base down

length of the eyelid, involving conjunctiva and

triangular piece of tarsal plate and conjunctiva is

tarsal plate (but not the skin), in the region of

resected along with double breasting of the

sulcus subtarsalis (2-3 mm above the lid margin).

orbicularis oculi muscle (Fig. 14.21).

The temporal end of the strip is incised by a full

ii. Bick’s procedure with Reeh’s modification: It is

thickness vertical incision. Pad and bandage is

useful in patients with associated horizontal lid

applied in such a way that the edge of lid is kept

laxity. In it a pentagonal full thickness resection

everted till healing occurs. After healing, the

of the lid tissue is performed.

lashes are directed away from the eye.

iii. Weiss operation. An incision involving skin,

iv. Jaesche-Arlt’s operation (Fig. 14.19B): The lid is

orbicularis and tarsal plate is given 3 mm below

split along the grey line up to a depth of

the lid margin, along the whole length of the

3-4 mm, from outer canthus to just lateral to the

eyelid. Mattress sutures are then passed through

punctum. Then a 4 mm wide crescentric strip of

the lower cut end of the tarsus to emerge on the

skin is removed from 3 mm above the lid margin.

skin, 1 mm below the lid margin. On tying the

After suturing the skin incision, the lash line will

sutures, the entropion is corrected by

be transplanted high. The gap created at the level

transpositioning of the tarsus (Fig. 14.22).

of grey line may be filled by a mucosal graft taken

from the lip.

v. Modified Ketssey’s operation (Transposition of

tarsoconjunctival wedge) (Fig.14.20): A horizontal

incision is made along the whole length of sulcus

subtarsalis

(2-3 mm above the lid margin)

involving conjunctiva and tarsal plate. The lower

piece of tarsal plate is undermined up to lid

Fig. 14.19. Operations for cicatricial entropion: A, skin,

muscle and tarsal wedge resection; B, Jaesche-Arlt’s

operation.

Fig. 14.20. Modified Ketssey’s operation.

DISEASES OF THE EYELIDS

351

iv. Tucking of inferior lid retractors (Jones, Reeh

and Wobig operation): It is performed in severe

cases or when recurrence occurs after the above

described operations. In this operation the

inferior lid retractors are strengthened by

tucking or plication procedure (Fig. 14.23).

ECTROPION

Out rolling or outward turning of the lid margin is

called ectropion.

Types

1. Senile ectropion. It is the commonest variety and

involves only the lower lids. It occurs due to senile

laxity of the tissues of the lids and loss of tone of the

orbicularis muscle (Fig. 14.24).

2. Cicatricial ectropion. It occurs due to scarring of

the skin and can involve both the lids (Fig. 14.25).

Common causes of skin scarring are: thermal burns,

chemical burns, lacerating injuries and skin ulcers.

Fig. 14.21. Modified Wheeler’s operation:

A, resection of orbicularis and tarsal plate;

B, double breasting of orbicularis.

Fig. 14.23. Tucking of inferior lid retractors:

Fig. 14.22. Weiss operation.

A, front view; B, cut section.

352

Comprehensive OPHTHALMOLOGY

Signs of the etiological condition such as skin scars

in cicatricial ectropion and seventh nerve palsy in

paralytic ectropion may also be seen.

Complications

Prolonged exposure may cause dryness and

thickening of the conjunctiva and corneal ulceration

(exposure keratitis). Eczema and dermatitis may occur

due to prolonged epiphora.

Treatment

Fig. 14.24. Senile ectropion lower eyelid.

1. Senile ectropion. Depending upon the severity,

following three operations are commonly performed:

i. Medial conjunctivoplasty. It is useful in mild

cases of ectropion involving punctal area. It

consists of excising a spindle-shaped piece of

conjunctiva and subconjunctival tissue from

below the punctal area (Fig. 14.26).

ii. Horizontal lid shortening. It is performed by a

full thickness pentagonal excision in patients

with moderate degree of ectropion (Fig. 14.27).

iii. Byron Smith’s modified Kuhnt-Szymanowski

operation. It is performed for severe degree of

ectropion which is more marked over the lateral

half of the lid. In it, a base up pentagonal full

Fig. 14.25. Cicatricial ectropion lower eyelid.

thickness excision from the lateral third of the

eyelid is combined with triangular excision of the

3. Paralytic ectropion. It results due to paralysis of

skin from the area just lateral to lateral canthus to

the seventh nerve. It mainly occurs in the lower lids.

elevate the lid (Fig. 14.28).

Common causes of facial nerve palsy are: Bell’s palsy,

head injury and infections of the middle ear.

4. Mechanical ectropion. It occurs in conditions

where either the lower lid is pulled down (as in

tumours) or pushed out and down (as in proptosis

and marked chemosis of the conjunctiva).

5. Spastic ectropion. It is a rare entity, seen in children

and young adults following spasm of the orbicularis,

where lids are well supported by the globe.

Clinical picture

Symptoms. Epiphora is the main symptom in

ectropion of the lower lid. Symptoms due to

associated chronic conjunctivitis include: irritation,

discomfort and mild photophobia.

Signs. Lid margin is outrolled. Depending upon the

degree of outrolling, ectropion can be divided into three

grades. In grade I ectropion only punctum is everted.

In grade II lid margin is everted and palpebral conjuncti-

va is visible while in grade III the fornix is also visible.

Fig. 14.26. Medial conjunctivoplasty.

DISEASES OF THE EYELIDS

353

Fig. 14.27. Horizontal lid shortening.

Fig. 14.29. V-Y operation.

5. Spastic ectropion. It is corrected by treating the

cause of blepharospasm.

SYMBLEPHARON

In this condition lids become adherent with the

eyeball as a result of adhesions between the palpebral

and bulbar conjunctiva.

Etiology

It results from healing of the kissing raw surfaces

upon the palpebral and bulbar conjunctiva. Its

Fig. 14.28. Modified Kuhnt-Szymanowski operation.

common causes are thermal or chemical burns,

membranous conjunctivitis, injuries, conjunctival

2. Paralytic ectropion. It can be corrected by a lateral

ulcerations, ocular pemphigus and Stevens-Johnson

tarsorrhaphy or palpebral sling operation, in which a

syndrome.

fascia lata sling is passed in the subcutaneous layer

all around the lid margins.

Clinical picture

3. Cicatricial ectropion. Depending upon the degree

It is characterised by difficulty in lid movements,

it can be corrected by any of the following operations:

diplopia (due to restricted ocular motility), inability

V-Y operation. It is indicated in mild degree

to close the lids (lagophthalmos) and cosmetic

ectropion. In it a V-shaped incision is given,

disfigurement.

skin is undermined and sutured in a Y-shaped

Fibrous adhesions between palpebral conjunctiva

pattern (Fig. 14.29).

and the bulbar conjunctiva and/or cornea (Fig. 14.30)

ii.

Z-plasty (Elschnig’s operation). It is useful in

may be present only in the anterior part (anterior

mild to moderate degree of ectropion.

symblepharon), or fornix (posterior symblepharon)

iii. Excision of scar tissue and full thickness skin

or the whole lid (total symblepharon).

grafting. It is performed in severe cases. Skin

graft may be taken from the upper lid, behind

Complications

the ear, or inner side of upper arm.

These include dryness, thickening and keratinisation

4. Mechanical ectropion. It is corrected by treating

of conjunctiva due to prolonged exposure and corneal

the underlying cause.

ulceration (exposure keratitis).

354

Comprehensive OPHTHALMOLOGY

Fig. 14.30. Symblepharon: Diagramatic depiction of anterior (A), posterior (B) and total symblepharon

(C); Clinical photographs of anterior (D) and posterior (E) symblepharon.

Treatment

Treatment. Lids should be separated by excision of

1. Prophylaxis. During the stage of raw surfaces,

adhesions between the lid margins and kept apart

the adhesions may be prevented by sweeping a

during healing process. When adhesions extend to

glass rod coated with lubricant around the

the angles, epithelial grafts should be given to

fornices several times a day. A large-sized,

prevent recurrences.

therapeutic, soft contact lens also helps in

preventing the adhesions.

BLEPHAROPHIMOSIS

2. Curative treatment consists of symblepharec-

In this condition the extent of the palpebral fissure is

tomy. The raw area created may be covered by

decreased. It appears contracted at the outer canthus.

mobilising the surrounding conjunctiva in mild

Etiology. It may be congenital or acquired, due to

cases. Conjunctival or buccal mucosal graft is

formation of a vertical skin fold at the lateral canthus

required in severe cases.

(epicanthus lateralis) following eczematous

ANKYLOBLEPHARON

contractions.

It refers to the adhesions between margins of the upper

Treatment. Usually no treatment is required. In

and lower lids. It may occur as a congenital anomaly or

marked cases, canthoplasty operation is performed.

may result after healing of chemical burns, thermal

burns, ulcers and traumatic wounds of the lid margins.

LAGOPHTHALMOS

Ankyloblepharon may be complete or incomplete. It is

This condition is characterised by inability to

usually associated with symblepharon.

voluntarily close the eyelids.

DISEASES OF THE EYELIDS

355

Etiology. It occurs in patients with paralysis of

orbicularis oculi muscle, cicatricial contraction of the

lids, symblepharon, severe ectropion, proptosis,

following over-resection of the levator muscle for

ptosis, and in comatosed patients. Physiologically

some people sleep with their eyes open (nocturnal

lagophthalmos)

Clinical picture. It is characterised by incomplete

closure of the palpebral aperture associated with

features of the causative disease.

Complications include conjunctival and corneal

xerosis and exposure keratitis.

Treatment. To prevent exposure keratitis artificial tear

drops should be instilled frequently and the open

palpebral fissure should be filled with an antibiotic

Fig. 14.31. Surgical technique of paramedian

eye ointment during sleep and in comatosed patients.

tarsorrhaphy

Soft bandage contact lens may be used to prevent

exposure keratitis.

2. Permanent tarsorrhaphy

Tarsorrhaphy may be performed to cover the

Indications. (i) Established cases of VII nerve palsy

exposed cornea when indicated. Measures should

be taken to treat the cause of lagophthalmos, wherever

where there is no chance of recovery; and (ii)

possible.

established cases of neuroparalytic keratitis with

severe loss of corneal sensations.

TARSORRHAPHY

Technique. It is performed at the lateral canthus to

In this operation adhesions are created between a

create permanent adhesions. The eyelids are

part of the lid margins with the aim to narrow down or

overlapped after excising a triangular flap of skin and

almost close the palpebral aperture.

orbicularis from the lower lid and corresponding

It is of two types: temporary and permanent.

triangular tarso-conjunctival flap from the upper lid.

1. Temporary tarsorrhaphy

BLEPHAROSPASM

Indications : (i) To protect the cornea when seventh

It refers to the involuntary, sustained and forceful

nerve palsy is expected to recover. (ii) To assist

closure of the eyelids.

healing of an indolent corneal ulcer. (iii) To assist in

Etiology. Blepharospasm occurs in two forms:

healing of skin-grafts of the lids in the correct position.

1. Essential (spontaneous) blepharospasm. It is a

Surgical techniques. This can be carried out as

rare idiopathic condition involving patients

median or paramedian tarsorrhaphy (Fig. 14.31).

between 45 and 65 years of age.

1. Incision. For paramedian tarsorrhaphy, about 5

2. Reflex blepharospasm. It usually occurs due to

mm long incision site is marked on the

reflex sensory stimulation through branches of

corresponding parts of the upper and lower lid

fifth nerve, in conditions such as : phlyctenular

margins, 3-mm on either side of the midline. An

keratitis, interstitial keratitis, corneal foreign body,

incision 2-mm deep is made in the grey line on the

corneal ulcers and iridocyclitis. It is also seen in

marked site and the marginal epithelium is then

excessive stimulation of retina by dazzling light,

excised taking care not to damage the ciliary line

stimulation of facial nerve due to central causes

anteriorly and the sharp lid border posteriorly.

and in some hysterical patients.

2. Suturing. The raw surfaces thus created on the

opposing parts of the lid margins are then sutured

Clinical features. Persistent epiphora may occur due

with double-armed 6-0 silk sutures passed through

to spasmodic closure of the canaliculi which may lead

a rubber bolster.

to eczema of the lower lid. Oedema of the lids is of

356

Comprehensive OPHTHALMOLOGY

frequent occurrence. Spastic entropion (in elderly

people) and spastic ectropion (in children and young

adults) may develop in long-standing cases.

Blepharophimosis may result due to contraction of

the skin folds following eczema.

Treatment. In essential blepharospasm Botulinum

toxin, injected subcutaneously over the orbicularis

muscle, blocks the neuromuscular junction and

relieves the spasm. Facial denervation may be

required in severe cases. In reflex blepharospasm, the

causative disease should be treated to prevent

recurrences. Associated complications should also

be treated.

PTOSIS

Abnormal drooping of the upper eyelid is called ptosis.

Normally, upper lid covers about upper one-sixth of

the cornea, i.e., about 2 mm. Therefore, in ptosis it

covers more than 2 mm.

Types and etiology

I. Congenital ptosis

It is associated with congenital weakness

(maldevelopment) of the levator palpebrae superioris

(LPS). It may occur in the following forms:

1. Simple congenital ptosis

(not associated with

any other anomaly) (Fig. 14.32A).

Fig. 14.32. Congental ptosis: A, simple;

2. Congenital ptosis with associated weakness of

B, blepharophimosis syndrome.

superior rectus muscle.

myasthenia gravis, dystrophia myotonica, ocular

3. As a part of blepharophimosis syndrome, which

myopathy, oculo-pharyngeal muscular dystrophy

comprises congenital ptosis, blepharophimosis,

and following trauma to the LPS muscle.

telecanthus and epicanthus inversus (Fig. 14.32B).

Aponeurotic ptosis. It develops due to defects of

4. Congenital synkinetic ptosis (Marcus Gunn jaw-

the levator aponeurosis in the presence of a

winking ptosis). In this condition there occurs

normal functioning muscle. It includes involutional

retraction of the ptotic lid with jaw movements

(senile) ptosis, postoperative ptosis

(which is

i.e., with stimulation of ipsilateral pterygoid muscle.

rarely observed after cataract and retinal

II. Acquired ptosis

detachment surgery), ptosis due to aponeurotic

Depending upon the cause it can be neurogenic,

weakness associated with blepharochalasis, and

myogenic, aponeurotic or mechanical.

in traumatic dehiscence or disinsertion of the

1. Neurogenic ptosis. It is caused by innervational

aponeurosis.

defects such as third nerve palsy, Horner’s

Mechanical ptosis. It may result due to excessive

syndrome, ophthalmoplegic migraine and multiple

weight on the upper lid as seen in patients with

sclerosis.

lid tumours, multiple chalazia and lid oedema. It

2. Myogenic ptosis. It occurs due to acquired

may also occur due to scarring (cicatricial ptosis)

disorders of the LPS muscle or of the myoneural

as seen in patients with ocular pemphigoid and

junction. It may be seen in patients with

trachoma.

DISEASES OF THE EYELIDS

357

Clinical evaluation

4. Assessment of levator function. It is determined

Following scheme may be adopted for work up of a

by the lid excursion caused by LPS muscle (Burke’s

ptosis patient:

method). Patient is asked to look down, and thumb of

I. History. It should include age of onset, family

one hand is placed firmly against the eyebrow of the

history, history of trauma, eye surgery and variability

patient (to block the action of frontalis muscle) by

in degree of the ptosis.

the examiner. Then the patient is asked to look up and

the amount of upper lid excursion is measured with a

II. Examination

ruler (Fig. 14.34) held in the other hand by the examiner.

1. Exclude pseudoptosis (simulated ptosis) on

Levator function is graded as follows:

inspection. Its common causes are: microphthalmos,

Normal

15 mm

anophthalmos, enophthalmos and phthisis bulbi.

Good

8 mm or more

2. Observe the following points in each case:

Fair

5-7 mm

i. Whether ptosis is unilateral or bilateral.

Poor

4 mm or less

ii. Function of orbicularis oculi muscle.

iii. Eyelid crease is present or absent.

5. Special investigations. Those required in patients

iv. Jaw-winking phenomenon is present or not.

with acquired ptosis are as follows:

v. Associated weakness of any extraocular

i. Tensilon test is performed when myasthenia is

muscle.

suspected. There occurs improvement of ptosis

vi. Bell’s phenomenon (up and outrolling of the

with intravenous injection of edrophonium

eyeball during forceful closure) is present or

(Tensilon) in myasthenia.

absent.

3. Measurement of amount (degree) of ptosis. In

unilateral cases, difference between the vertical height

of the palpebral fissures of the two sides indicates

the degree of ptosis (Fig. 14.33). In bilateral cases it

can be determined by measuring the amount of cornea

covered by the upper lid and then subtracting 2 mm.

Depending upon its amount the ptosis is graded as

Mild

2 mm

Moderate

3 mm

Severe

4 mm

Fig. 14.33. Measurement of degree of

Fig. 14.34. Assessment of levator function : A, Looking

ptosis in millimetres.

down; B, Looking up.

358

Comprehensive OPHTHALMOLOGY

ii. Phenylephrine test is carried out in patients

relation to cornea during operation on the table in

suspected of Horner’s syndrome.

individual case. However, a rough estimate in different

grades of ptosis is as follows:

iii. Neurological investigations may be required to

Moderate ptosis

find out the cause in patient with neurogenic

Level of LPS Amount of LPS to be

ptosis.

Function resected

6. Photographic record of the patient should be

Good 16-17 mm (minimal)

maintained for comparison. Photographs should be

Fair 18-22 mm (moderate)

taken in primary position as well as in up and down

Poor

23-24 mm (maximum)

gazes.

Severe ptosis

Fair levator

23-24 mm (maximum

Treatment

function LPS resected)

Techniques. Levator muscle may be resected by either

I. Congenital ptosis. It almost always needs surgical

conjunctival or skin approach.

correction. In severe ptosis, surgery should be

i. Conjunctival approach (Blaskowics’ operation):

performed at the earliest to prevent stimulus

This technique is comparatively easy but not

deprivation amblyopia. However, in mild and moderate

suitable for large amount of resection. In it LPS

ptosis, surgery should be delayed until the age of 3-

muscle is exposed by an incision made through

4 years, when accurate measurements are possible.

the conjunctiva near the tarsal border, after the

Congenital ptosis can be treated by any of the

upper lid is doubly everted over a Desmarre’s lid

following operations:

retractor (Fig. 14.36).

1. Fasanella-Servat operation. It is performed in

ii. Skin approach (Everbusch’s operation): It is a

cases having mild ptosis (1.5-2mm) and good levator

more frequently employed technique. It allows

function. In it, upper lid is everted and the upper tarsal

comparatively better exposure of the LPS muscle

border along with its attached Muller’s muscle and

through a skin incision along the line of future lid

conjunctiva are resected (Fig. 14.35).

fold (Fig. 14.37).

2. Levator resection. It is a very commonly performed

3. Frontalis sling operation (Brow suspension):

operation for moderate and severe grades of ptosis.

This is performed in patients having severe ptosis

It is contraindicated in patients having severe ptosis

with no levator function. In this operation, lid is

with poor levator function.

anchored to the frontalis muscle via a sling

(Fig.

Amount of levator resection required: Most of the

14.38). Fascia lata or some non-absorbable material

surgeons find it out by adjusting the lid margin in

(e.g., supramide suture) may be used as sling.

Fig. 14.35. Fasanella-Servat operation.

Fig. 14.36. Conjunctival approach for levator resection.

DISEASES OF THE EYELIDS

359

TUMOURS OF THE LIDS

Almost all types of tumours arising from the skin,

connective tissue, glandular tissue, blood vessels,

nerves and muscles can involve the lids. A few

common tumours are listed and only the important

ones are described here.

Classification

1. Benign tumours. These include; simple papilloma,

naevus, angioma, haemangioma, neurofibroma

and sebaceous adenoma.

2. Pre-cancerous conditions. These are solar

keratosis, carcinoma-in-situ and xeroderma

pigmentosa.

3. Malignant tumours. Commonly observed tumours

Fig. 14.37. Skin approach for levator resection.

include squamous cell carcinoma, basal cell

carcinoma, malignant melanoma and sebaceous

gland adenocarcinoma.

BENIGN TUMOURS

1. Papillomas

These are the most common benign tumours arising

from the surface epithelium. These occur in two forms:

squamous papillomas and seborrhoeic keratosis

(basal cell papillomas, senile verrucae).

i. Squamous papillomas occur in adults, as very

slow growing or stationary, raspberry-like growths

or as a pedunculated lesion, usually involving

the lid margin. Its treatment consists of simple

excision.

ii. Seborrhoeic keratosis occurs in middle-aged and

older persons. Their surface is friable, verrucous

and slightly pigmented.

2. Xanthelasma

These are creamy-yellow plaque-like lesions which

Fig. 14.38. Frontalis sling operation.

frequently involve the skin of upper and lower lids

near the inner canthus (Fig. 14.39). Xanthelasma

II. Acquired ptosis. Efforts should be made to find

occurs more commonly in middle-aged women.

out the underlying cause and if possible treat it. In

Xanthelasma represents lipid deposits in histiocytes

neurogenic ptosis conservative treatment should be

in the dermis of the lid. These may be associated with

carried out and surgery deferred at least for 6 months.

diabetes mellitus or high cholesterol levels.

Surgical procedures (when required) are essentially

Treatment: Excision may be advised for cosmetic

the same as described for congenital ptosis. However,

reasons; but recurrences are common.

the amount of levator resection required is always

less than the congenital ptosis of the same degree.

3. Haemangioma

Further, in most cases the simple Fasanella-Servat

Haemangiomas of the lids are common tumours. These

procedure is adequate.

occur in three forms:

360

Comprehensive OPHTHALMOLOGY

iii. Cavernous haemangiomas are developmental and

usually occur after first decade of life. It consists of

large endothelium-lined vascular channels and

usually does not show any regression. Treatment is

similar to capillary haemangiomas.

4. Neurofibroma

Lids and orbits are commonly affected in

neurofibromatosis (von Recklinghausen’s disease).

The tumour is usually of plexiform type (Fig. 14.41).

Fig. 14.39. Xanthelasma

i. Capillary haemangioma (Fig. 14.40) is the most

common variety which occurs at or shortly after birth,

often grows rapidly and in many cases resolves

spontaneously by the age of 7 years. These may be

superficial and bright red in colour (strawberry

naevus) or deep and bluish or violet in colour. They

consist of proliferating capillaries and endothelial

cells.

Treatment. Unless the tumour is very large it may be

left untouched until the age of 7 years (as in many

cases it resolves spontaneously). The treatment

modalities include:

Excision: It is performed in small tumours.

Fig. 14.41. Neurofibroma upper eyelid.

Intralesional steroid (triamcinolone) injection is

effective in small to medium size tumours.

MALIGNANT TUMOURS

Alternate day high dose steroid therapy regime

1. Basal-cell carcinoma

is recommended for large diffuse tumours.

Superficial radiotherapy may also be given for

It is the commonest malignant tumour of the lids

large tumours.

(90%) usually seen in elderly people. It is locally

ii. Naevus flammeus (port wine stain). It may occur

malignant and involves most commonly lower lid

pari passu or more commonly as a part of Sturge-

(50%) followed by medial canthus (25%), upper lid

Weber syndrome. It consists of dilated vascular

(10-15%) and outer canthus (5-10%).

channels and does not grow or regress like the

Clinical features. It may present in four forms:

capillary haemangioma.

Noduloulcerative basal cell carcinoma is the most

common presentation. It starts as a small nodule which

undergoes central ulceration with pearly rolled

margins. The tumour grows by burrowing and

destroying the tissues locally like a rodent and hence

the name rodent ulcer (Fig. 14.42).

Other rare presentations include: non-ulcerated

nodular form, sclerosing or morphea type and

pigmented basal cell carcinoma.

Histological features. The most common pattern is

solid basal cell carcinoma in which the dermis is

invaded by irregular masses of basaloid cells with

Fig. 14.40. Capillary haemangioma.

characteristic peripheral palisading appearance.

DISEASES OF THE EYELIDS

361

(which may be mistaken for a chalazion). Which then

grows to form a big growth (Fig. 14.44). Rarely, a

diffuse tumour along the lid margin may be mistaken

as chronic blepharitis. Surgical excision with

reconstruction of the lids is the treatment of choice.

Recurrences are common.

4. Malignant melanoma (melanocarcinoma)

It is a rare tumour of the lid (less than 1% of all eyelid

lesions). It may arise from a pre-existing naevus, but

usually arises de novo from the melanocytes present

in the skin.

Clinically, it often appears as a flat or slightly

elevated naevus which has variegated pigmentation

Fig. 14.42. Basal cell carcinoma lower eyelid.

and irregular borders. It may ulcerate and bleed.

Metastasis. The tumour spreads locally as well as to

Treatment

distant sites by lymphatics and blood stream.

Surgery. Local surgical excision of the tumour

Treatment. It is a radio-resistant tumour. Therefore,

along with a 3 mm surrounding area of normal

surgical excision with reconstruction of the lid is the

skin with primary repair is the treatment of choice.

treatment of choice.

Radiotherapy and cryotherapy should be given

only in inoperable cases for palliation.

2. Squamous cell carcinoma

It forms the second commonest malignant tumour of

the lid. Its incidence (5%) is much less than the basal

cell carcinoma. It commonly arises from the lid margin

(mucocutaneous junction) in elderly patients. Affects

upper and lower lids equally.

Clinial features. It may present in two forms: An

ulcerated growth with elevated and indurated margins

is the common presentation (Fig. 14.43). The second

form, fungating or polypoid verrucous lesion without

ulceration, is a rare presentation.

Metastasis. It metastatises in preauricular and sub-

Fig. 14.43. Squamous cell carcinoma of upper lid.

mandibular lymph nodes.

Histological features. It is characterised by an

irregular downward proliferation of epidermal cells

into the dermis. In well-differentiated form, the

malignant cells have a whorled arrangement forming

epithelial pearls which may contain laminated keratin

material in the centre.

Treatment on the lines of basal cell carcinoma.

3. Sebaceous gland carcinoma

It is a rare tumour arising from the meibomian glands.

Clinically, it usually presents initially as a nodule

Fig. 14.44. Meibomian gland carcinome lower eyelid.

CHAPTER

rimal Apparatus

15^Lac

APPLIED ANATOMY

DACRYOCYSTITIS

Structure

Congenital

Functions

Chronic dacryocystitis

Secretion of tears

Acute dacryocystitis

Elimination of tears

Surgical technique of DCR and DCT

THE TEAR FILM

THE DRY EYE

SWELLINGS OF THE LACRIMAL GLAND

Sjogren’s syndrome

Dacryoadenitis

THE WATERING EYE

Mickulicz’s syndrome

Etiology

Dacryopes

Clinical evaluation

Tumours

Accessory lacrimal glands (Fig. 14.4)

APPLIED ANATOMY

1. Glands of Krause. These are microscopic glands

lying beneath the palpebral conjunctiva between

The lacrimal apparatus comprises (1) Main lacrimal

fornix and the edge of tarsus. These are about 42

gland, (2) Accessory lacrimal glands, and (3) Lacrimal

in the upper fornix and 6-8 in the lower fornix.

passages, which include: puncta, canaliculi, lacrimal

2. Glands of Wolfring. These are present near the

sac and nasolacrimal duct (NLD) (Fig. 15.1).

upper border of the superior tarsal plate and

along the lower border of inferior tarsus.

Main lacrimal gland

It consists of an upper orbital and a lower palpebral

Structure, blood supply and nerve supply

part. (1) Orbital part is larger, about the size and

Structure. All lacrimal glands are serous acini, similar

shape of a small almond, and is situated in the fossa

in structure to the salivary glands. Microscopically

for lacrimal gland at the outer part of the orbital plate

of frontal bone. It has got two surfaces — superior

and inferior. The superior surface is convex and lies

in contact with the bone. The inferior surface is

concave and lies on the levator palpebrae superioris

muscle. (2) Palpebral part is small and consists of

only one or two lobules. It is situated upon the course

of the ducts of orbital part from which it is separated

by LPS muscle. Posteriorly, it is continuous with the

orbital part.

Ducts of lacrimal gland. Some 10-12 ducts pass

downward from the main gland to open in the lateral

part of superior fornix. One or two ducts also open in

the lateral part of inferior fornix.

Fig. 15.1. The lacrimal apparatus.

364

Comprehensive OPHTHALMOLOGY

these consist of glandular tissue (acini and ducts),

There are numerous membranous valves in the

connective tissue and puncta.

NLD, the most important is the valve of Hasner, which

is present at the lower end of the duct and prevents

Blood supply. Main lacrimal gland is supplied by

reflux from the nose.

lacrimal artery which is a branch of ophthalmic artery.

Nerve supply. (1) Sensory supply comes from lacrimal

nerve, a branch of the ophthalmic division of the fifth

TEAR FILM

nerve. (2) Sympathetic supply comes from the carotid

plexus of the cervical sympathetic chain. (3)

Structure of tear film

Secretomotor fibres are derived from the superior

Wolff was the first to describe the detailed structure

salivary nucleus.

of the fluid covering the cornea and called it

precorneal film. He described this film to consist of

Lacrimal passages

three layers, which from posterior to anterior are

1. Lacrimal puncta. These are two small, rounded or

mucus layer, aqueous layer and lipid or oily layer

oval openings on upper and lower lids, about 6 and

(Fig. 15.2).

6.5 mm, respectively, temporal to the inner canthus.

1. Mucus layer. It is the innermost and thinnest

Each punctum is situated upon a slight elevation

stratum of the tear film. It consists of mucin secreted

called lacrimal papilla which becomes prominent in

by conjunctival goblet cells and glands of Manz. It

old age. Normally the puncta dip into the lacus

converts the hydrophobic corneal surface into

lacrimalis (collection of tear fluid in the inner canthus).

hydrophilic one.

2. Lacrimal canaliculi. These join the puncta to the

2. Aqueous layer. The bulk of tear film is formed by

lacrimal sac. Each canaliculus has two parts: vertical

this intermediate layer which consists of tears

(1-2 mm) and horizontal (6-8 mm) which lie at right

secreted by the main and accessory lacrimal glands.

angle to each other. The horizontal part converges

The tears mainly comprise of water and small

towards inner canthus to open in the sac. The two

quantities of solutes such as sodium chloride, sugar,

urea and proteins. Therefore, it is alkaline and salty

canaliculi may open separately or may join to form

in taste. It also contains antibacterial substances like

common canaliculus which opens immediately into

lysozyme, betalysin and lactoferrin.

the outer wall of lacrimal sac. A fold of mucosa at this

3. Lipid or oily layer. This is the outermost layer of

point forms the valve of Rosenmuller which prevents

tear film formed at air-tear interface from the secretions

reflux of tears.

of Meibomian, Zeis, and Moll glands. This layer

3. Lacrimal sac. It lies in the lacrimal fossa located in

prevents the overflow of tears, retards their

the anterior part of medial orbital wall. The lacrimal

evaporation and lubricates the eyelids as they slide

fossa is formed by lacrimal bone and frontal process

over the surface of the globe.

of maxilla. It is bounded by anterior and posterior

lacrimal crests. When distended, lacrimal sac is about

15 mm in length and 5-6 mm in breadth. It has got

three parts: fundus (portion above the opening of

canaliculi), body (middle part) and the neck (lower

small part which is narrow and continuous with the

nasolacrimal duct).

4. Nasolacrimal duct (NLD). It extends from neck of

the lacrimal sac to inferior meatus of the nose. It is

about 15-18 mm long and lies in a bony canal formed

by the maxilla and the inferior turbinate. Direction of

the NLD is downwards, backwards and laterally.

Externally its location is represented by a line joining

inner canthus to the ala of nose. The upper end of the

NLD is the narrowest part.

Fig. 15.2. Structure of the tear film.

DISEASES OF THE LACRIMAL APPARATUS

365

Functions of tear film

THE DRY EYE

1. Keeps the cornea and conjunctiva moist.

2. It provides oxygen to the corneal epithelium.

The dry eye per se is not a disease entity, but a

3. Washes away debris and noxious irritants.

symptom complex occurring as a sequelae to

4. Prevents infection due to presence of antibac-

deficiency or abnormalities of the tear film.

terial substances.

Etiology

5. Facilitates movements of the lids over the globe.

1. Aqueous tear deficiency. It is also known as

Secretion of tears

keratoconjunctivitis sicca. It is seen in conditions

Tears are continuously secreted throughtout the day

like congenital alacrimia, paralytic hyposecretion,

by accessory (basal secretion) and main (reflex

primary and secondary Sjogren’s syndrome, Riley Day

secretion) lacrimal glands. Reflex secretion is in

syndrome and idiopathic hyposecretion.

response to sensations from the cornea and

2. Mucin deficiency dry eye. It occurs when goblet

conjunctiva, probably produced by evaporation and

cells are damaged, as in hypovitaminosis A

break-up of tear film. Hyperlacrimation occurs due to

(xerophthalmia) and conjunctival scarring diseases

irritative sensations from the cornea and conjunctiva.

such as Stevens-Johnson syndrome, trachoma,

Afferent pathway of this secretion is formed by fifth

chemical burns, radiations and ocular pemphigoid.

nerve and efferent by parasympathetic (secreto-

3. Lipid deficiency and abnormalities. Lipid

motor) supply of lacrimal gland.

deficiency is extremely rare. It has only been

described in some cases of congenital anhydrotic

Elimination of tears

ectodermal dysplasia along with absence of

Tears flow downward and medially across the surface

meibomian glands. However, lipid abnormalities are

of eyeball to reach the lower fornix and then via lacus

quite common in patients with chronic blepharitis and

lacrimalis in the inner canthus. From where they are

chronic meibomitis.

drained by lacrimal passages into the nasal cavity

4. Impaired eyelid function. It is seen in patients

(Fig. 15.3A). This is brought about by an active

with Bell’s palsy, exposure keratitis, dellen,

lacrimal pump mechanism constituted by fibres of the

symblepharon, pterygium, nocturnal lagophthalmos

orbicularis (especially Horner’s muscle) which are

and ectropion.

inserted on the lacrimal sac. When the eye lids close

5. Epitheliopathies. Owing to the intimate

during blink, contraction of these fibres distends the

relationship between the corneal surface and tear film,

fundus of the sac, creates therein a negative pressure

alterations in corneal epithelium affect the stability

which syphons the tears through punctum and

of tear film.

canaliculi into the sac (Fig. 15.3B). When the eyelids

open, the Horner’s muscle relaxes, the lacrimal sac

Clinical features

collapses and a positive pressure is created which

Symptoms suggestive of dry eye include irritation,

forces the tears down the nasolacrimal duct into the

foreign body (sandy) sensation, feeling of dryness,

nose (Fig. 15.3C). Therefore, in atonia of sac, tears

itching, non-specific ocular discomfort and

are not drained through the lacrimal passages, in

chronically sore eyes not responding to a variety of

spite of anatomical patency; resulting in epiphora.

drops instilled earlier.

Signs of dry eye include: presence of stringy mucus

and particulate matter in the tear film, lustureless

ocular surface, conjunctival xerosis, reduced or absent

marginal tear strip and corneal changes in the form of

punctate epithelial erosions and filaments.

Tear film tests

These include tear film break-up time (BUT), Schirmer-

I test, vital staining with Rose Bengal, tear levels of

Fig.

15.3. Elimination of tears by lacrimal pump mechanism.

lysozyme and lactoferrin, tear osmolarity and

366

Comprehensive OPHTHALMOLOGY

conjunctival impression cytology. Out of these BUT,

Treatment

Schirmer-I test and Rose Bengal staining are most

At present, there is no cure for dry eye. The following

important and when any two of these are positive,

treatment modalities have been tried with variable

diagnosis of dry eye syndrome is confirmed.

results:

1. Tear film break-up (BUT). It is the interval between

1. Supplementation with tear substitutes. Artificial

a complete blink and appearance of first randomly

tears remains the mainstay in the treatment of dry

distributed dry spot on the cornea. It is noted after

eye. These are available as drops, ointments and slow-

instilling a drop of fluorescein and examining in a

release inserts. Mostly available artificial tear drops

cobalt-blue light of a slit-lamp. BUT is an indicator of

contain either cellulose derivatives (e.g., 0.25 to 0.7%

adequacy of mucin component of tears. Its normal

methyl cellulose and 0.3% hypromellose) or polyvinyl

values range from 15 to 35 seconds. Values less than

alcohol (1.4%).

10 seconds imply an unstable tear film.

2. Topical cyclosporine (0.05%, 0.1%) is reported to

2. Schirmer-I test. It measures total tear secretions. It

be very effective drug for dry eye in many recent

is performed with the help of a 5 × 35 mm strip of

studies. It helps by reducing the cell-mediated

Whatman-41 filter paper which is folded 5 mm from

inflammation of the lacrimal tissue.

one end and kept in the lower fornix at the junction of

3. Mucolytics, such as 5 percent acetylcystine used

lateral one-third and medial two-thirds. The patient is

4 times a day help by dispersing the mucus threads

asked to look up and not to blink or close the eyes

and decreasing tear viscosity.

(Fig. 15.4). After 5 minutes wetting of the filter paper

4. Topical retinoids have recently been reported to

strip from the bent end is measured. Normal values of

be useful in reversing the cellular changes (squamous

Schirmer-I test are more than 15 mm. Values of 5-10

metaplasia) occurring in the conjunctiva of dry eye

mm are suggestive of moderate to mild

patients.

5. Preservation of existing tears by reducing

keratoconjunctivitis sicca (KCS) and less than 5 mm

evaporation and decreasing drainage.

of severe KCS.

Evaporation can be reduced by decreasing room

3. Rose Bengal staining. It is a very useful test for

temperature, use of moist chambers and protective

detecting even mild cases of KCS. Depending upon

glasses.

the severity of KCS three staining patterns A, B and

Punctal occlusion to decrease drainage can be

C have been described: ‘C’ pattern represents mild or

carried out by collagen implants, cynoacrylate

early cases with fine punctate stains in the

tissue adhesives, electrocauterisation, argon laser

interpalpebral area; ‘B’ the moderate cases with

occlusion and surgical occlusion to decrease the

extensive staining; and ‘A’ the severe cases with

drainage of tears in patients with very severe

confluent staining of conjunctiva and cornea.

dry eye.

SJOGREN’S SYNDROME

It is an autoimmune chronic inflammatory disease with

multi-system involvement. It typically occurs in

women between 40 and 50 years of age. Its main

feature is an aqueous deficiency dry eye — the

keratoconjunctivitis sicca (KCS). In primary Sjogren’s

syndrome patients present with sicca complex- a

combination of KCS and xerostomia (dryness of

mouth). In secondary Sjogren’s syndrome dry eye

and/or dry mouth are associated with an autoimmune

disease, commonly rheumatoid arthritis. Its

pathological features include focal accumulation and

infiltration by lymphocytes and plasma cells with

Fig. 15.4. Schirmer test.

destruction of lacrimal and salivary glandular tissue.

DISEASES OF THE LACRIMAL APPARATUS

367

Punctal causes include:

THE WATERING EYE

Eversion of lower punctum: It is commonly

seen in old age due to laxity of the lids. It may

It is characterised by overflow of tears from the

also occur following chronic conjunctivitis,

conjunctival sac. The condition may occur either due

chronic blepharitis and due to any cause of

to excessive secretion of tears (hyperlacrimation) or

ectropion.

may result from obstruction to the outflow of normally

Punctal obstruction: There may be congenital

secreted tears (epiphora).

absence of puncta or cicatricial closure

following injuries, burns or infections. Rarely

Etiology

a small foreign body, concretion or cilia may

(A) Causes of hyperlacrimation

also block the punctum. Prolonged use of

drugs like idoxuridine and pilocarpine is also

1. Primary hyperlacrimation. It is a rare condition

associated with punctal stenosis.

which occurs due to direct stimulation of the lacrimal

Causes in the canaliculi. Canalicular obstruction

gland. It may occur in early stages of lacrimal gland

may be congenital or acquired due to foreign

tumours and cysts and due to the effect of strong

body, trauma, strictures and canaliculitis.

parasympathomimetic drugs.

Commonest cause of canaliculitis is actinomyces.

2. Reflex hyperlacrimation. It results from stimulation

Causes in the lacrimal sac. These include

of sensory branches of fifth nerve due to irritation of

congenital mucous membrane folds, traumatic

cornea or conjunctiva. It may occur in multitude of

strictures, dacryocystitis, specific infections like

conditions which include:

tuberculosis and syphilis, dacryolithiasis, tumours

Affections of the lids: Stye, hordeolum internum,

and atonia of the sac.

acute meibomitis, trichiasis, concretions and

Causes in the nasolacrimal duct. Congenital

entropion.

lesions include non-canalization, partial

Affections of the conjunctiva: Conjunctivits which

canalization or imperforated membranous valves.

may be infective, allergic, toxic, irritative or

Acquired causes of obstruction are traumatic

traumatic.

strictures, inflammatory strictures, tumours and

Affections of the cornea: These include, corneal

diseases of the surrounding bones.

abrasions, corneal ulcers and non-ulcerative

Clinical evaluation of a case of ‘Watering eye’

keratitis.

1. Ocular examination with diffuse illumination

Affections of the sclera: Episcleritis and scleritis.

using magnification should be carried to rule out

Affections of uveal tissue: Iritis, cyclitis,

any cause of reflex hypersecretion located in lids,

iridocyclitis.

conjunctiva, cornea, sclera, anterior chamber, uveal

Acute glaucomas.

tract and so on. This examination should also exclude

Endophthalmitis and panophthalmitis.

punctal causes of epiphora and any swelling in the

Orbital cellulitis.

sac area.

3. Central lacrimation (psychical lacrimation). The

2. Regurgitation test. A steady pressure with index

exact area concerned with central lacrimation is still

finger is applied over the lacrimal sac area above the

not known. It is seen in emotional states, voluntary

medial palpebral ligament. Reflux of mucopurulent

lacrimation and hysterical lacrimation.

discharge indicates chronic dacryocystitis with

obstruction at lower end of the sac or the nasolacrimal

(B) Causes of epiphora

duct.

Inadequate drainage of tears may occur due to

3. Fluorescein dye disappearance test (FDDT). In

physiological or anatomical (mechanical) causes.

this test 2 drops of fluorescein dry eye are instilled in

I Physiological cause is ‘lacrimal pump’ failure due

both the conjunctival sacs and observations are made

to lower lid laxity or weakness of orbicularis muscle.

after 2 minutes. Normally, no dye is seen in the

II Mechanical obstruction in lacrimal passages may

conjunctival sac. A prolonged retention of dye in

lie at the level of punctum, canaliculus, lacrimal sac

conjunctival sac indicates inadequate drainage which

or nasolacrimal duct.

may be due to atonia of sac or mechanical obstruction.

368

Comprehensive OPHTHALMOLOGY

4. Lacrimal syringing test. It is performed after

at the opening of nasolacrimal duct. After

topical anaesthesia with 4 percent xylocaine (Fig. 15.5).

minutes the cotton bud is removed and inspected.

Normal saline is pushed into the lacrimal sac from

A dye-stained cotton bud indicates adequate

lower punctum with the help of a syringe and lacrimal

drainage through the lacrimal passages and the

cannula.

cause of watering is primary hypersecretion

(further investigations should aim at finding the

cause of primary hypersecretion). While the

unstained cotton bud

(negative test) indicates

either a partial obstruction or failure of lacrimal

pump mechanism. To differentiate between these

conditions, Jones dye test-II is performed.

ii. Jones secondary test (Jones test II). When primary

test is negative, the cotton bud is again placed

in the inferior meatus and lacrimal syringing is

performed. A positive test suggests that dye was

present in the sac but could not reach the nose

due to partial obstruction. A negative test

indicates presence of lacrimal pump failure.

6. Dacryocystography. It is valuable in patients with

mechanical obstruction. It tells the exact site, nature

and extent of block (Fig. 15.6). In addition, it also

gives information about mucosa of the sac, presence

of any fistulae, diverticulae, stone, or tumour in the

sac.

To perform it a radiopaque material such as lipiodol,

pentopaque, dianosil or condray-280 is pushed in the

Fig. 15.5. Technique of lacrimal syringing.

sac with the help of a lacrimal cannula and X-rays are

taken after 5 minutes and 30 minutes to visualize the

A free passage of saline through lacrimal passages

entire passage. For better anatomical visualization the

into the nose rules out any mechanical

obstruction.

In the presence of partial obstruction, saline

passes with considerable pressure on the syringe.

In the presence of obstruction no fluid passes

into nose and it may reflux through same punctum

(indicating obstruction in the same or common

canaliculus) or through opposite punctum

(indicating obstruction in the lower sac or

nasolacrimal duct).

5. Jones dye tests. These are performed when partial

obstruction is suspected. Jones dye tests are of no

value in the presence of total obstruction.

i. Jones primary test (Jones test I). It is performed

to differentiate between watering due to partial

obstruction of the lacrimal passages from that

due to primary hypersecretion of tears. Two drops

of 2 percent fluorescein dye are instilled in the

conjunctival sac and a cotton bud dipped in 1

percent xylocaine is placed in the inferior meatus

Fig. 15.6. Normal dacryocystogram.

DISEASES OF THE LACRIMAL APPARATUS

369

modified technique known as substraction

Clinical picture

macrodacryocystography with canalicular

Congenital dacryocystitis usually presents as a mild

catheterisation should be preferred.

grade chronic inflammation. It is characterised by:

7. Radionucleotide dacryocystography (lacrimal

1. Epiphora, usually developing after seven days

scintillography). It is a non-invasive technique to

of birth. It is followed by copious mucopurulent

assess the functional efficiency of lacrimal drainage

discharge from the eyes.

apparatus. A radioactive tracer (sulphur colloid or

2. Regurgitation test is usually positive, i.e., when

technitium) is instilled into the conjunctival sac and

pressure is applied over the lacrimal sac area,

its passage through the lacrimal drainage system is

purulent discharge regurgitates from the lower

visualised with an Anger gamma camera (Fig. 15.7).

punctum.

3. Swelling on the sac area may appear eventually.

Differential diagnosis

Congenital dacryocystitis needs to be differentiated

from other causes of watering in early childhood

especially ophthalmia neonatorum and congenital

glaucoma.

Complications

When not treated in time it may be complicated by

recurrent conjunctivitis, acute on chronic dacryocys-

Fig. 15.7. Lacrimal scintillography showing: A, normal

titis, lacrimal abscess and fistulae formation.

lacrimal excretory system on right side; B, obstruction at

the junction of lacrimal sac and nasolacrimal on left side.

Treatment

It depends upon the age at which the child is brought.

The treatment modalities employed are as follows:

DACRYOCYSTITIS

1. Massage over the lacrimal sac area and topical

antibiotics constitute the treatment of congenital

Inflammation of the lacrimal sac is not an uncommon

NLD block, up to 6-8 weeks of age. Massage

condition. It may occur in two forms: congenital and

adult dacryocystitis.

increases the hydrostatic pressure in the sac and

helps to open up the membranous occlusions. It

CONGENITAL DACRYOCYSTITIS

should be carried out at least 4 times a day to be

followed by instillation of antibiotic drops. This

It is an inflammation of the lacrimal sac occurring in

conservative treatment cures obstruction in about

newborn infants; and thus also known as

90 percent of the infants.

dacryocystitis neonatorum.

2. Lacrimal syringing

(irrigation) with normal

Etiology

saline and antibiotic solution. It should be added

It follows stasis of secretions in the lacrimal sac due

to the conservative treatment if the condition is

to congenital blockage in the nasolacrimal duct. It

not cured up to the age of 2 months. Lacrimal

is of very common occurrence. As many as 30 percent

irrigation helps to open the membranous occlusion

of newborn infants are believed to have closure of

by exerting hydraulic pressure. Syringing may be

nasolacrimal duct at birth; mostly due to ‘membranous

carried out once or twice a week.

occlusion’ at its lower end, near the valve of Hasner.

3. Probing of NLD with Bowman’s probe. It should

Other causes of congenital NLD block are: presence

be performed, in case the condition is not cured

of epithelial debris, membranous occlusion at its

by the age of 3-4 months. Some surgeons prefer

upper end near lacrimal sac, complete non-

to wait till the age of 6 months. It is usually

canalisation and rarely bony occlusion. Common

performed under general anaesthesia. While

bacteria associated with congenital dacryocystitis

performing probing, care must be taken not to

are staphylococci, pneumococci and streptococci.

injure the canaliculus. In most instances a single

370

Comprehensive OPHTHALMOLOGY

probing will relieve the obstruction. In case of

2. Foreign bodies in the sac may block opening of

failure, it may be repeated after an interval of 3-

NLD.

4 weeks.

3. Excessive lacrimation, primary or reflex, causes

4. Intubations with silicone tube may be performed

stagnation of tears in the sac.

if repeated probings are failure. The silicone tube

4. Mild grade inflammation of lacrimal sac due to

should be kept in the NLD for about six months.

associated recurrent conjunctivitis may block the

5. Dacryocystorhinostomy (DCR) operations: When

NLD by epithelial debris and mucus plugs.

the child is brought very late or repeated probing

5. Obstruction of lower end of the NLD by nasal

is a failure, then conservative treatment by

diseases such as polyps, hypertrophied inferior

massaging, topical antibiotics and intermittent

concha, marked degree of deviated nasal septum,

lacrimal syringing should be continued till the

tumours and atrophic rhinitis causing stenosis

age of 4 years. After this, DCR operation should

may also cause stagnation of tears in the lacrimal

be performed.

sac.

ADULT DACRYOCYSTITIS

C. Source of infection. Lacrimal sac may get infected

Adult dacryocystitis may occur in an acute or a

from the conjunctiva, nasal cavity (retrograde

chronic form.

spread), or paranasal sinuses.

CHRONIC DACRYOCYSTITIS

D. Causative organisms. These include: staphylo-

Chronic dacryocystitis is more common than the acute

cocci, pneumococci, streptococci and Pseudomo-

dacryocystitis.

nas pyocyanea. Rarely chronic granulomatous

infections like tuberculosis, syphilis, leprosy and

Etiology

occasionally rhinosporiodosis may also cause

The etiology of chronic dacryocystitis is

dacryocystitis.

multifactorial. The well-established fact is a vicious

cycle of stasis and mild infection of long duration.The

Clinical picture

etiological factors can be grouped as under:

Clinical picture of chronic dacryocystitis may be

A. Predisposing factors

divided into four stages:

1. Stage of chronic catarrhal dacryocystitis. It is

1. Age. It is more common between 40 and 60 years

of age.

characterised by mild inflammation of the lacrimal sac

2. Sex. The disease is predominantly seen in females

associated with blockage of NLD. In this stage the

(80%) probably due to comparatively narrow

only symptom is watering eye and sometimes mild

lumen of the bony canal.

redness in the inner canthus. On syringing the lacrimal

3. Race. It is rarer among Negroes than in Whites;

sac, either clear fluid or few fibrinous mucoid flakes

as in the former NLD is shorter, wider and less

regurgitate. Dacryocystography reveals block in NLD,

sinuous.

a normal-sized lacrimal sac with healthy mucosa.

4. Heredity. It plays an indirect role. It affects the

2. Stage of lacrimal mucocoele. It follows chronic

facial configuration and so also the length and

stagnation causing distension of lacrimal sac. It is

width of the bony canal.

characterised by constant epiphora associated with

5. Socio-economic status. It is more common in low

a swelling just below the inner canthus (Fig. 15.8).

socio-economic group.

Milky or gelatinous mucoid fluid regurgitates from

6. Poor personal hygiene. It is also an important

the lower punctum on pressing the swelling.

predisposing factor.

Dacryocystography at this stage reveals a distended

sac with blockage somewhere in the NLD.

B. Factors responsible for stasis of tears in

lacrimal sac

Sometimes due to continued chronic infection,

opening of both the canaliculi into the sac are blocked

1. Anatomical factors, which retard drainage of tears

and a large fluctuant swelling is seen at the inner

include: comparatively narrow bony canal, partial

canthus with a negative regurgitation test. This is

canalization of membranous NLD and excessive

called encysted mucocele.

membranous folds in NLD.

DISEASES OF THE LACRIMAL APPARATUS

371

blockage of NLD which usually does not open up

with repeated lacrimal syringing or even probing.

2. Dacryocystorhinostomy (DCR). It should be the

operation of choice as it re-establishes the lacrimal

drainage. However, before performing surgery, the

infection especially in pyocoele should be controlled

by topical antibiotics and repeated lacrimal syringings.

3. Dacryocystectomy (DCT). It should be performed

only when DCR is contraindicated. Indications of

DCT include: (i) Too young (less than 4 years) or too

old (more than 60 years) patient. (ii) Markedly

shrunken and fibrosed sac. (iii) Tuberculosis, syphilis,

Fig. 15.8. Lacrimal mucocele.

leprosy or mycotic infections of sac. (iv) Tumours of

sac. (v) Gross nasal diseases like atrophic rhinitis (vi)

3. Stage of chronic suppurative dacryocystitis. Due

An unskilled surgeon, because it is said that, a good

to pyogenic infections, the mucoid discharge

‘DCT’ is always better than a badly done ‘DCR’.

becomes purulent, converting the mucocele into

4. Conjunctivodacryocystorhinostomy (CDCR). It is

‘pyocoele’. The condition is characterised by

performed in the presence of blocked canaliculi.

epiphora, associated recurrent conjunctivitis and

swelling at the inner canthus with mild erythema of

ACUTE DACRYOCYSTITIS

the overlying skin. On regurgitation a frank purulent

discharge flows from the lower punctum. If openings

Acute dacryocystitis is an acute suppurative

of canaliculi are blocked at this stage the so called

inflammation of the lacrimal sac, characterised by

encysted pyocoele results.

presence of a painful swelling in the region of sac.

4. Stage of chronic fibrotic sac. Low grade repeated

Etiology

infections for a prolonged period ultimately result in

It may develop in two ways:

a small fibrotic sac due to thickening of mucosa, which

1. As an acute exacerbation of chronic dacryo-

is often associated with persistent epiphora and

cystitits.

discharge. Dacryocystography at this stage reveals

2. As an acute peridacryocystitis due to direct

a very small sac with irregular folds in the mucosa.

involvement from the neighbouring infected

Complications

structures such as: paranasal sinuses, surrounding

bones and dental abscess or caries teeth in the

Chronic intractable conjunctivitis, acute on chronic

upper jaw.

dacryocystitis.

Causative organisms. Commonly involved are

Ectropion of lower lid, maceration and eczema of

Streptococcus haemolyticus, Pneumococcus and

lower lid skin due to prolonged watering.

Simple corneal abrasions may become infected

Staphylococcus.

leading to hypopyon ulcer.

Clinical picture

If an intraocular surgery is performed in the

Clinical picture of acute dacryocystitis can be divided

presence of dacryocystitis, there is high risk of

into 3 stages:

developing endophthalmitis. Because of this,

1. Stage of cellulitis. It is characterised by a painful

syringing of lacrimal sac is always done before

swelling in the region of lacrimal sac associated with

attempting any intraocular surgery.

epiphora and constitutional symptoms such as fever

Treatment

and malaise. The swelling is red, hot, firm and tender.

1. Conservative treatment by repeated lacrimal

Redness and oedema also spread to the lids and cheek.

syringing. It may be useful in recent cases only. Long-

When treated resolution may occur at this stage.

standing cases are almost always associated with

However, if untreated, self-resolution is rare.

372

Comprehensive OPHTHALMOLOGY

2. Stage of lacrimal abscess. Continued inflammation

Complications

causes occlusion of the canaliculi due to oedema.

These include:

The sac is filled with pus, distends and its anterior

Acute conjunctivitis,

wall ruptures forming a pericystic swelling. In this

Corneal abraision which may be converted to

way, a large fluctuant swelling the lacrimal abscess is

corneal ulceration,

formed. It usually points below and to the outer side

Lid abscess,

of the sac, owing to gravitation of pus and presence

Osteomyelitis of lacrimal bone,

of medial palpebral ligament in the upper part

Orbital cellulitis,

(Fig. 15.9).

Facial cellulitis and acute ethmoiditis.

3. Stage of fistula formation. When the lacrimal

Rarely cavernous sinus thrombosis and very

abscess is left unattended, it discharges sponta-

rarely generalized septicaemia may also develop.

neously, leaving an external fistula below the medial

palpebral ligament (Fig. 15.10). Rarely, the abscess

Treatment

may open up into the nasal cavity forming an

1. During cellulitis stage. It consists of systemic

internal fistula.

and topical antibiotics to control infection; and

systemic anti-inflammatory analgesic drugs and

hot fomentation to relieve pain and swelling.

2. During stage of lacrimal abscess. In addition to

the above treatment when pus starts pointing on

the skin, it should be drained with a small incision.

The pus should be gently squeezed out, the

dressing done with betadine soaked roll gauze.

Later on depending upon condition of the

lacrimal sac either DCT or DCR operation should

be carried out, otherwise recurrence will occur.

3. Treatment of external lacrimal fistula. After

controlling the acute infection with systemic

antibiotics, fistulectomy along with DCT or DCR

operation should be performed.

SURGICAL TECHNIQUE OF

Fig. 15.9. Acute dacryocystitis: Stage of

DACRYOCYSTORHINOSTOMY

lacrimal abscess.

Dacryocystorhinostomy (DCR) operation can be

performed by two techniques:

Conventional external approach DCR, and

Endonasal DCR

Conventional external approach DCR (Fig. 15.11)

1. Anaesthesia. General anaesthesia is preferred,

however, it may be performed with local infiltration

anaesthesia in adults.

2. Skin incision. Either a curved incision along the

anterior lacrimal crest or a straight incision 8 mm

medial to the medial canthus is made.

3. Exposure of medial palpebral ligament (MPL)

and Anterior lacrimal crest. MPL is exposed by

blunt dissection and cut with scissors to expose

Fig. 15.10. Acute dacryocystitis: Stage of external

lacrimal fistula.

the anterior lacrimal crest.

DISEASES OF THE LACRIMAL APPARATUS

373

4. Dissection of lacrimal sac. Periosteum is separated

8. Suturing of flaps. Posterior flap of the nasal

from the anterior lacrimal crest and along with the

mucosa is sutured with posterior flap of the sac

lacrimal sac is reflected laterally with blunt

using 6-0 vicryl or chromic cat gut sutures. It is

dissection exposing the lacrimal fossa.

followed by suturing of the anterior flaps.

5. Exposure of nasal mucosa. A 15 mm × 10 mm

9. Closure. MPL is sutured to periosteum, orbicularis

bony osteum is made by removing the anterior

muscle is sutured with 6-0 vicryl and skin is

lacrimal crest and the bones forming lacrimal

closed with 6-0 silk sutures.

fossa, exposing the thick pinkish white nasal

Endonasal DCR

mucosa.

Presently many eye surgeons, alone or in

6. Preparation of flaps of sac. A probe is introduced

into the sac through lower canaliculus and the

collaboration with the ENT surgeons, are pereferring

endonasal DCR over conventional external approach

sac is incised vertically. To prepare anterior and

posterior flaps, this incision is converted into H

DCR because of its advantages (described below).

shape.

surgical steps of endonasal DCR are (Fig. 15.12):

7. Fashioning of nasal mucosal flaps. is also done

1. Preparation and anaesthesia. Nasal mucosa is

by vertical incision converted into H shape.

prepared for 15-30 minutes before operation with nasal

Fig. 15.11. Surgical steps of external dacryocystorhinostomy: A, skin incision; B, exposure of bony lacrimal fossa;

C, preparation of bony osteum and exposure of nasal mucosa; D, preparation of flaps of the nasal mucosa and

lacrimal sac; E, suturing of posterior flaps; F, suturing of anterior flaps.

374

Comprehensive OPHTHALMOLOGY

decongestant drops and local anaesthetic agent.

help of endoscope, the sac area which is

Conjunctival sac is anaesthetised with topically

transilluminated by the light pipe is identified (Fig.

instilled 2% lignocaine. Then 3 ml of lignocaine 2%

15.12A) and a further injection of lignocaine with

with 1 in 2 lac adrenaline is injected into the medial

adrenaline is made below the nasal mucosa in this area.

parts of upper and lower eyelids and via sub-

3. Creation of opening in the nasal mucosa, bones

caruncular injection to the lacrimal fossa region.

2. Identification of sac area. A 20-gauge light pipe is

forming the lacrimal fossa and posteromedial wall

inserted via the upper canaliculi into the sac. With the

of sac can be accomplished by two techniques:

Fig. 15.12. Surgical steps of endonasal DCR: A, Endoscopic identification of sac area in the middle meatus;

B, opening created in the middle meatus; C, Stenting of rhinostomy opening with fine silicone tubes.

DISEASES OF THE LACRIMAL APPARATUS

375

i By cutting the tissues with appropriate

infection. Dacryoadenitis secondary to local

instruments or

infections occurs in trauma, erysipelas of the face,

ii By ablating with Holmium YAG laser (endoscopic

conjunctivitis (especially gonococcal and staphy-

laser assited DCR).

lococcal) and orbital cellulitis. Dacryoadenitis

secondary to systemic infections is associated with

Note: The size of opening is about 12 mm × 10 mm

mumps, influenza, infectious mononucleosis and

(Fig. 15.12B).

measles.

4. Stenting of rhinostomy opening. The outflow

system is then stented using fine silicone tubes

Clinical picture. Acute inflammation of the palpebral

passed via the superior and inferior canaliculi into

part is characterised by a painful swelling in the lateral

the rhinostomy and secured with a process of knotting

part of the upper lid. The lid becomes red and swollen

(Fig. 15.12C). Nasal packing and dressing is done.

with a typical S-shaped curve of its margin

5. Postoperative care and removal of sialistic

(Fig. 15.13). Acute orbital dacryoadenitis produces

lacrimal stents. After 24 hours of operation nasal

some painful proptosis in which the eyeball moves

packs are removed and patient is advised to use

down and in. A fistula in the upper and lateral quadrant

decongestent, antibiotic and steroid nasal drops for

of the upper lid may develop as a complication of

3-4 weeks. The sialistic lacrimal stents are removed 8-

suppurative dacryoadenitis.

12 weeks after surgery and the nasal drops are

continued further for 2-3 weeks.

Table 15.1: Advantages and disadvantages of

endonasal DCR vis-a-vis external DCR

Advantages and disadvantages of endoscopic

DCR vis-a-vis external DCR

Endoscopic DCR

External DCR

Advantages and disadvantages of endoscopic

Advantages

Disadvantages

DCR vis-a-vis external DCR are summerized in

No external scar

Cutaneous scar

Table 15.1.

Relatively blood less

Relatively more

surgery

bleeding during

SURGICAL TECHNIQUE OF

surgery

DACRYOCYSTECTOMY (DCT)

Better visualisation of

nasal pathology

1 to 4 steps are same as for external DCR operation.

Less chances of injury to

Potential injury to

5. Removal of lacrimal sac. After exposing the sac,

ethmoidal vessels and

adjacent medial

it is separated from the surrounding structures

cribri form plate.

canthus structures

by blunt dissection followed by cutting its

Less time consuming

More operating time

connections with the lacrimal canaliculi. It is then

(15-30 mins) since nasal

(45-60 minutes)

held with artery forceps and twisted 3-4 times to

mucosal flaps and sac

wall flaps are not made.

tear it away from the nasolacrimal duct (NLD).

No post operative

Significant

6. Curettage of bony NLD. It is done with the help

morbidity

postoperative

of a lacrimal curette to remove the infected parts

morbidity

of membranous NLD.

7. Closure. It is done as for external DCR

Disadvantages

Advantages

(Step 9).

Less success rate

More success rate

(70-90%)

(95%)

Requires skilled ophthal-

Easily performed by

SWELLINGS OF THE

mologist and/or rhinologist.

ophthalmologists

LACRIMAL GLAND

Expensive equipment

Cheap (expensive

equipment not

DACRYOADENITIS

required)

Dacryoadenitis may be acute or chronic.

Requires reasonable

Does not require

access to middle

familiarity with

I. Acute dacryoadenitis

meatus and familiarity

endoscopic

Etiology. It may develop as a primary inflammation

with endoscopic anatomy.

anatomy

of the gland or secondary to some local or systemic

376

Comprehensive OPHTHALMOLOGY

TUMOURS OF THE LACRIMAL GLAND

These are not so common and in a simplified way can

be classified as below:

1. Lymphoid tumours and inflammatory pseudo-

tumours. These constitute approximately

50 percent of cases.

2. Benign epithelial tumours. These include ‘benign

mixed tumours’ which account for 25 percent

cases.

3. Malignant epithelial tumours. These also

Fig. 15.13. A patient with bilateral dacryoadenitis:

constitute

25 percent of cases and include:

note, s-shaped curve of upper eyelid.

malignant mixed tumour, adenoid cystic

carcinoma, mucoepidermoid carcinoma and

Treatment. It consists of a course of appropriate

adenocarcinoma.

systemic antibiotic, analgesic and anti-inflammatory

drugs along with hot fomentation. When pus is

Benign mixed tumour

formed, incision and drainage should be carried out.

It is also known as pleomorphic adenoma and occurs

predominantly in young adult males.

II. Chronic dacryoadenitis

Clinically it presents as a slowly progressive painless

It is characterised by engorgement and simple

swelling in the upper-outer quadrant of the orbit

hypertrophy of the gland.

displacing the eyeball downwards and outwards

Etiology. Chronic dacryoadenitis may occur: (i) as

(Fig. 15.14). It is locally invasive and may infiltrate its

sequelae to acute inflammation; (ii) in association with

own pseudocapsule to involve the adjacent

chronic inflammations of conjunctiva and; (iii) due to

periosteum. Histologically, it is characterised by

systemic diseases such as tuberculosis, syphilis and

presence of pleomorphic myxomatous tissue, just like

sarcoidosis.

benign mixed tumour of salivary gland.

Clinical features. These include (i) a painless swelling

Treatment consists of complete surgical removal with

in upper and outer part of lid associated with ptosis;

the capsule. Recurrences are very common following

(ii) eyeball may be displaced down and in; and (iii)

incomplete removal.

diplopia may occur in up and out gaze.

On palpation, a firm lobulated mobile mass may be

Malignant mixed tumour

felt under the upper and outer rim of the orbit.

It occurs in the older age group as compared to the

benign mixed tumour. It presents as a painful swelling

Differential diagnosis from other causes of lacrimal

of short duration. Histologically, areas resembling

gland swellings is best made after fine needle

benign mixed tumour are seen along with the

aspiration biopsy or incisional biopsy.

adenocarcinomatous areas.

Treatment consists of treating the cause.

MIKULICZ’S SYNDROME

It is characterised by bilaterally symmetrical

enlargement of the lacrimal and salivary glands

associated with a variety of systemic diseases. These

include: leukaemias, lymphosarcomas, benign

lymphoid hyperplasia, Hodgkin’s disease, sarcoidosis

and tuberculosis.

DACRYOPES

It is a cystic swelling, which occurs due to retention

of lacrimal secretions following blockage of the

Fig. 15.14. Down and out displacement of right eyeball in

lacrimal ducts.

a patient with benign mixed tumour.

Diseases of

CHAPTER

APPLIED ANATOMY

Orbital periostitis

Cavernous sinus thrombosis

PROPTOSIS

Specific chronic orbital inflammations

Classification

Idiopathic orbital inflammatory disease

Causes

Investigations

GRAVES’ OPHTHALMOPATHY

Thyrotoxic exophthalmos

ENOPHTHALMOS

Thyrotropic exophthalmos

DEVELOPMENTAL ANOMALIES

ORBITAL TUMOURS

OF THE ORBIT

ORBITAL INFLAMMATIONS

BLOW-OUT FRACTURES

Preseptal cellulitis

ORBITAL SURGERY

Orbital cellulitis and intraorbital abscess

Orbitotomy

Orbital mucormycosris

Exenteration

The lateral wall of the orbit is triangular in shape. It

APPLIED ANATOMY

covers only posterior half of the eyeball. Therefore,

palpation of the retrobulbar tumours is easier from

BONY ORBIT

this side. Because of its advantageous anatomical

The bony orbits are quadrangular truncated pyramids

position, a surgical approach to the orbit by lateral

situated between the anterior cranial fossa above and

orbitotomy is popular.

the maxillary sinuses below (Fig. 16.1). Each orbit is

The roof is triangular in shape and is formed mainly

about 40 mm in height, width and depth and is formed

by the orbital plate of frontal bone.

by portions of seven bones : (1) frontal, (2) maxilla,

Base of the orbit is the anterior open end of the

(3) zygomatic, (4) sphenoid, (5) palatine, (6) ethmoid

orbit. It is bounded by thick orbital margins.

and (7) lacrimal. It has four walls (medial, lateral,

The orbital apex (Fig. 16.2). It is the posterior end of

superior and inferior), base and an apex.

orbit. Here the four orbital walls converge. It has two

The medial walls of two orbits are parallel to each

orifices, the optic canal which transmits optic nerve

other and, being thinnest, are frequently fractured

and ophthalmic artery and the superior orbital fissure

during injuries as well as during orbitotomy

which transmits a number of nerves, arteries and veins

operations and, it also accounts for ethmoiditis being

(Fig. 13.2).

the commonest cause of orbital cellulitis.

ORBITAL FASCIA

The inferior orbital wall (floor) is triangular in shape

and being quite thin is commonly involved in blow-

It is a thin connective tissue membrane lining various

out fractures and is easily invaded by tumours of the

intraorbital structures. Though, it is one continuous

maxillary antrum.

tissue, but for the descriptive convenience it has been

DISEASES OF ORBIT

379

divided into fascia bulbi, muscular sheaths,

PROPTOSIS

intermuscular septa, membranous expansions of the

extraocular muscles and ligament of Lockwood.

It is defined as forward displacement of the eyeball

Fascia bulbi (Tenon’s capsule) envelops the globe

beyond the orbital margins. Though the word

from the margins of cornea to the optic nerve. Its

exophthalmos (out eye) is synonymous with it; but

lower part is thickened to form a sling or hammock on

somehow it has become customary to use the term

which the globe rests; this is called ‘suspensory

exophthalmos for the displacement associated with

ligament of Lockwood’.

thyroid disease.

CONTENTS OF THE ORBIT

CLASSIFICATION

The volume of each orbit is about

30 cc.

Proptosis can be divided into following clinical

Approximately one-fifth of it is occupied by the

groups:

eyeball. Other contents of the orbit include: part of

Unilateral proptosis

optic nerve, extraocular muscles, lacrimal gland,

Bilateral proptosis

lacrimal sac, ophthalmic artery and its branches, third,

Acute proptosis

fourth and sixth cranial nerves and ophthalmic and

Intermittent proptosis

maxillary divisions of the fifth cranial nerve,

Pulsating proptosis

sympathetic nerve, orbital fat and fascia.

ETIOLOGY

SURGICAL SPACES IN THE ORBIT

Important causes of proptosis in each clinical group

These are of importance as most orbital pathologies

are listed here:

tend to remain in the space in which they are formed.

Therefore, their knowledge helps the surgeon in

A. Causes of unilateral proptosis include:

choosing the most direct surgical approach. Each orbit

1. Congenital conditions. These include: dermoid

is divisible into four surgical spaces (Fig. 16.3).

cyst, congenital cystic eyeball, and orbital

teratoma.

1. The subperiosteal space. This is a potential space

2. Traumatic lesions. These are: orbital haemorrhage,

between the bone and the periorbita (periosteum).

retained intraorbital foreign body, traumatic

2. The peripheral space. It is bounded peripherally

aneurysm and emphysema of the orbit.

by the periorbita and internally by the four recti

3. Inflammatory lesions. Acute inflammations are

with thin intermuscular septa. Tumours present

orbital cellulitis, abscess, thrombophlebitis,

here produce eccentric proptosis and can usually

panophthalmitis, and cavernous sinus thrombosis

be palpated. For peribulbar anaesthesia, injection

(proptosis is initially unilateral but ultimately

is made in this space.

becomes bilateral). Chronic inflammatory lesions

include: pseudotumours, tuberculoma, gumma and

3. The central space. It is also called muscular cone

sarcoidosis.

or retrobulbar space. It is bounded anteriorly by

4. Circulatory disturbances and vascular lesions.

the Tenon’s capsule lining back of the eyeball

These are: angioneurotic oedema, orbital varix

and peripherally by the four recti muscles and

and aneurysms.

their intermuscular septa in the anterior part. In

5. Cysts of orbit. These include: haematic cyst,

the posterior part, it becomes continuous with

implantation cyst and parasitic cyst (hydatid cyst

the peripheral space. Tumours lying here usually

and cysticercus cellulosae).

produce axial proptosis. Retrobulbar injections

6. Tumours of the orbit. These can be primary,

are made in this space.

secondary or metastatic.

4. Tenon’s space. It is a potential space around

7. Mucoceles of paranasal sinuses, especially frontal

the eyeball between the sclera and Tenon’s

(most common), ethmoidal and maxillary sinus are

capsule.

common causes of unilateral proptosis.

DISEASES OF ORBIT

381

B. Causes of bilateral proptosis include:

(ii) to ascertain whether the proptosis is unilateral

1. Developmental anomalies of the skull:

or bilateral; (iii) to note the shape of the skull;

craniofacial dysostosis e.g., oxycephaly (tower

and (iv) to observe whether proptosis is axial or

skull).

eccentric.

2. Osteopathies: Osteitis deformans, rickets and

Palpation. It should be carried out for retro-

acromegaly.

displacement of globe to know compressibility of

3. Inflammatory conditions: Mikulicz’s syndrome

the tumour, for orbital thrill, for any swelling

and late stage of cavernous sinus thrombosis.

around the eyeball, regional lymph nodes and

4. Endocrinal exophthalmos: It may be thyrotoxic

orbital rim.

or thyrotropic.

Auscultation. It is primarily of value in searching

5. Tumours: These include symmetrical lymphoma

for abnormal vascular communications that

or lymphosarcoma, secondaries from neurobla-

generate a bruit, such as caroticocavernous fistula.

stoma, nephroblastoma, Ewing’s sarcoma and

Transillumination. It is helpful in evaluating

leukaemic infiltration.

anterior orbital lesions.

6. Systemic diseases: Histiocytosis, systemic

Visual acuity. Orbital lesions may reduce visual

amyloidosis, xanthomatosis and Wegener’s

acuity by three mechanisms: refractive changes

granulomatosis.

due to pressure on back of the eyeball, optic

C. Causes of acute proptosis. It develops with

nerve compression and exposure keratopathy.

extreme rapidity (sudden onset). Its common causes

Pupil reactions. The presence of Marcus Gunn

are: orbital emphysema fracture of the medial orbital

pupil is suggestive of optic nerve compression.

wall, orbital haemorrhage and rupture of ethmoidal

Fundoscopy. It may reveal venous engorgement,

mucocele.

haemorrhage, papilloedema and optic atrophy.

D. Cause of intermittent proptosis. This type of

Choroidal folds and opticociliary shunts may be

proptosis appears and disappears of its own. Its

seen in patients with meningiomas.

common causes are: orbital varix, periodic orbital

Ocular motility. It is restricted in thyroid

oedema, recurrent orbital haemorrhage and highly

ophthalmopathy, extensive tumour growths and

vascular tumours.

neurological deficit.

E. Causes of pulsating proptosis. It is caused by

Exophthalmometry. It measures protrusion of the

pulsating vascular lesions such as carotico-

apex of cornea from the outer orbital margin (with

cavernous fistula and saccular aneurysm of

the eyes looking straight ahead). Normal values

ophthalmic artery. Pulsating proptosis also occurs

vary between 10 and 21 mm and are symmetrical

due to transmitted cerebral pulsations in conditions

in both eyes. A difference of more than 2 mm

associated with deficient orbital roof. These include

between the two eyes is considered significant.

congenital meningocele or meningoencephalocele,

The simplest instrument to measure proptosis is

neurofibromatosis and traumatic or operative hiatus.

Luedde’s exophthalmometer (Fig. 16.4). However,

Investigation of a case of proptosis

the Hertel’s exophthalmometer (Fig. 16.5) is the

most commonly used instrument. Its advantage

I. Clinical evaluation

is that it measures the two eyes simultaneously.

(A) History. It should include: age of onset, nature of

onset, duration, progression, chronology of orbital

signs and symptoms and associated symptoms.

should be conducted to rule out systemic causes of

proptosis such as thyrotoxicosis, histiocytosis, and

(B) Local examination. It should be carried out as

follows:

primary tumours elsewhere in the body (secondaries

1. Inspection.

(i) To differentiate proptosis from

in orbits). Otorhinolaryngological examination is

pseudoproptosis which is seen in patients with

necessary when the paranasal sinus or a

buphthalmos, axial high myopia, retraction of

nasopharyngeal mass apears to be a possible

upper lid and enophthalmos of the opposite eye;

etiological factor.

382

Comprehensive OPHTHALMOLOGY

mass. A combination of axial (CAT) and coronal

(CCT) cuts enables a three-dimensional

visualisation. CT scan is capable of visualising

various structures like globe, extraocular muscles

and optic nerves. Further, this technique is also

useful in examining areas adjacent to the orbits

such as orbital walls, cranial cavity, paranasal

sinuses and nasal cavity. Its main disadvantage

is the inability to distinguish between

pathologically soft tissue masses which are

radiologically isodense.

3. Ultrasonography. It is a non-radiational non-

invasive, completely safe and extremely valuable

initial scanning procedure for orbital lesions. In

Fig. 16.4. Luedde’s exophthalmometer.

the diagnosis of orbital lesions, it is superior to

CT scanning in actual tissue diagnosis and can

usually differentiate between solid, cystic,

infiltrative and spongy masses.

4. Magnetic resonance imaging (MRI). It is a major

advance in the imaging techniques. It is very

sensitive for detecting differences between normal

and abnormal tissues and has excellent image

resolution. The technique produces tomographic

images which are superficially very similar to CT

scan but rely on entirely different physical

principles for their production.

Fig. 16.5. Hertel’s exophthalmometer.

(B) Invasive procedures

II. Laboratory investigations

1. Orbital venography. It is required in patients

These should include:

who are clinically suspected of having orbital

Thyroid function tests,

varix. It confirms the diagnosis and also outlines

the size and extent of the anomaly which facilitates

Haematological studies (TLC, DLC, ESR, VDRL

proper surgical planning.

test),

2. Carotid angiography. It is now performed only

Casoni’s test (to rule out hydatid cyst),

in cases of pulsating exophthalmos and in those

Stool examination for cysts and ova, and

associated with a bruit or thrill. The principal role

Urine analysis for Bence Jones proteins for

of carotid angiography in orbital diagnosis is to

multiple myeloma.

identify the location and extent of ophthalmic

artery aneurysms, and the pathologic circulation

III. Imaging Technique

associated with various arteriovenous

(A) Non-invasive techniques

communications along the ophthalmic artery-

1. Plain X-rays. It is still the most frequently used

cavernous sinus complex. It is also useful to

initial radiological examination. Commonly required

identify the feeding vessels prior to undertaking

exposures are in the Caldwell view, the Water’s

surgery in patients with vascular orbital tumours.

view, a lateral view and the Rhese view (for optic

3. Radioisotope studies. These are, nowadays,

foramina). X-ray signs of orbital diseases include

sparingly employed. Radioisotope arteriography

enlargement of orbital cavity, enlargement of optic

has been found useful in proptosis of vascular

foramina, calcification and hyperostosis.

lesions. In this technique, sodium pertechnetate

2. Computed tomography scanning. It is very useful

Tc 99 m is injected intravenously and its flow is

for determining the location and size of an orbital

visualised by a gamma scintillation camera.

DISEASES OF ORBIT

383

IV. Histopathological studies

DEVELOPMENTAL ANOMALIES

The exact diagnosis of many orbital lesions cannot

OF THE ORBIT

be made without the help of histopathological studies

which can be accomplished by following techniques:

Developmental anomalies of the orbit are commonly

associated with abnormalities of skull and facial

1. Fine-needle aspiration biopsy (FNAB). It is a

bones. They are frequently hereditary (autosomal

reliable, accurate (95%), quick and easy technique

dominant) in origin.

for cytodiagnosis in orbital tumours. The biopsy

Ocular features of developmental orbital anomalies

aspirate is obtained under direct vision in an

may be one or more of the following:

obvious mass and under CT scan or

Proptosis,

ultrasonographic guidance in retrobulbar mass

Strabismus,

using a 23-gauge needle.

Papilloedema, and

2. Incisional biopsy. Undoubtedly, for accurate

Optic atrophy.

tissue diagnosis a proper biopsy specimen at

Details of such anomalies are beyond the scope of

least 5 to 10 mm in length is required. However,

the book. However, a few salient features of some

the scope of incisional biopsy in the diagnosis of

anomalies are mentioned below:

orbital tumours is not clearly defined. It may be

Craniosynostosis

undertaken along with frozen tissue study in

Craniosynostosis results from premature closure of

infiltrative lesions which remain undiagnosed.

one or more cranial sutures. Depending upon the

3. Excisional biopsy. It should always be preferred

suture involved craniosynostosis may be of following

over incisional biopsy in orbital masses which

types:

are well encapsulated or circumscribed. It is

Anomaly

Suture closed

performed by anterior orbitotomy for a mass in

prematurely

the anterior part of orbit and by lateral orbitotomy

Brachycephaly

All cranial sutures

for a retrobulbar mass.

(clover-leaf skull)

Oxycephaly (tower-

Coronal suture

ENOPHTHALMOS

shaped skull)

Scophocephaly (boat-

Sagittal suture

It is the inward displacement of the eyeball. About 50

shaped skull)

percent cases of mild enophthalmos are misdiagnosed

Trigonocephaly (egg-

Frontal suture

as having ipsilateral ptosis or contralateral proptosis.

shaped skull)

Common causes are:

Ocular features include:

1. Congenital. Microphthalmos and maxillary

1. Bilateral proptosis due to shallow orbits.

hypoplasia.

2. Strabismus—either esotropia or exotropia.

2. Traumatic. Blow out fractures of floor of the

3. Papilloedema and/or optic atrophy.

orbit.

Craniofacial dysostosis

3. Post-inflammatory. Cicatrization of extraocular

Craniofacial dysostosis (Crouzon’s syndrome) refers

muscles as in the pseudotumour syndromes.

to premature closure of all sutures (brachycephaly)

4. Paralytic enophthalmos. It is seen in Horner’s

associated with maxillary hyperplasia.

syndrome

(due to paralysis of cervical

Ocular features include (1) Proptosis due to shallow

sympathetics).

orbits, (2) Divergent squint, (3) Hypertelorism i.e.,

widely separated eyeballs (increased interpupillary

5. Atrophy of orbital contents. Senile atrophy of

distance), and (4) optic atrophy.

orbital fat, atrophy due to irradiation of malignant

Systemic features are: (1) mental retardation, (2) high-

tumour, following cicatrizing metastatic carcinoma

arched palate, (3) irregular dentition, and (4) hooked

and due to scleroderma.

(parrot beak) nose.

384

Comprehensive OPHTHALMOLOGY

Mandibulofacial dysostosis

4. Orbital thrombophlebitis

Mandibulofacial dysostosis (Treacher-Collin

5. Tenonitis

syndrome) refers to a condition resulting from

6. Cavernous sinus thrombosis

hypoplasia of zygoma and mandible.

(B) Chronic orbital inflammations

Ocular features include: (1) indistinct inferior orbital

I. Specific inflammations

margin, (2) coloboma of the lower eyelid, and (3) anti-

1. Tuberculosis

mongoloid slant.

Systemic features are: (1) macrostomia with high-

2. Syphilis

arched palate, (2) external ear deformity, and (3) bird-

3. Actinomycosis

like face.

4. Mycotic infections e.g., mucormycosis

5. Parasitic infestations

Median facial cleft syndrome

II. Chronic non-specific inflammations

The main ocular features of this developmental

1. Idiopathic orbital inflammatory disease

anomaly are: (1) hypertelorism, (2) telecanthus and

(Inflammatory pseudotumours)

(3) divergent squint; and main systemic features

2. Tolosa-Hunt syndrome

include: (1) cleft-nose, lip and palate, and (2) V-shaped

3. Chronic orbital periostitis

frontal hair line (widow’s peak).

Salient features of some orbital inflammations of

Oxycephaly-syndactyle (Apert’s syndrome)

interest are described here.

Systemic features include: (1) tower skull with flat

occiput, (2) mental retardation, (3) ventricular septal

PRESEPTAL CELLULITIS

defect, (3) high arched palate, and (4) syndactyly of

Preseptal (or periorbital) cellulitis refers to infection

the fingers and toes.

of the subcutaneous tissues anterior to the orbital

Ocular features are: (1) hypertelorism—increased IPD,

septum. Strictly speaking it is not an orbital disease

(2) bilateral proptosis due to shallow orbits, (3)

but is included here under because the facial veins

congenital ptosis, (4) antimongoloid slant, and (5)

are valveless and preseptal cellulitis may spread

divergent squint.

posteriorly to produce orbital cellulitis.

Hypertelorism

Causes

It is a condition of widely separated eyeballs resulting

Causative organisms are usually staphylococcus

from widely separated orbits and broad nasal bridge.

Hypertelorism may occur de novo or as a part of

aureus or sreptococcus pyogenes.

various syndromes such as Apert’s syndrome,

Modes of intection. The organisms may invade the

Crouzon’s syndrome and median facial cleft

preseptal tissue by any of the following modes.

syndrome.

1. Exogenous infection may result following skin

Ocular features of hypertelorism are: (1) increased

laceration or insect bites.

interpupillary distance (IPD)—may be 85 mm

2. Extension from local infections such as from an

(normally, average IPD in an adult is 60 mm),

acute hordeolum or acute dacryocystitis.

(2) telecanthus, (3) divergent squint, (4) anti-

3. Endogenous infection may occur by haemato-

mongoloid slant, and (5) optic atrophy may be

genous spread from remote infection of the middle

associated in some cases due to narrow optic canal.

ear or upper respiratory tract.

Clinical features

ORBITAL INFLAMMATIONS

Preseptal cellulitis presents as inflammatory oedema

CLASSIFICATION

of the eyelids and periorbital skin with no involvement

(A) Acute orbital and related inflammations

of the orbit.Thus, Characteristic features are painful

1. Pre-septal cellulitis

acute periorbital swelling, erythema and hyperaemia

2. Orbital cellulitis and intraorbital abscess

of the lids (Fig. 16.6). There may be associated fever

3. Orbital osteoperiostitis

and leukocytosis.

DISEASES OF ORBIT

385

system the protective agents are limited to local

phagocytic elements provided by the orbital reticular

tissue; (ii) due to tight compartments, the intraorbital

pressure is raised which augments the virulence of

infection causing early and extensive necrotic

sloughing of the tissues; and (iii) as in most cases

the infection spreads as thrombophlebitis from the

surrounding structures, a rapid spread with extensive

necrosis is the rule.

Clinical features

Symptoms include swelling and severe pain which is

increased by movements of eye or pressure. Other

Fig. 16.6. Preseptal cellulitis.

associated symptoms may be fever, nausea, vomiting,

Treatment

prostrations and sometimes loss of vision.

Consists of oral antibiotics and anti inflammatory

Signs of orbital cellulitis (Fig. 16.7) are:

drug, with close follow up care.

A marked swelling of lids characterised by woody

hardness and redness.

ORBITAL CELLULITIS AND INTRAORBITAL

A marked chemosis of conjunctiva, which may

ABSCESS

protrude and become desiccated or necrotic.

Orbital cellulitis refers to an acute infection of the

The eyeball is proptosed axially.

soft tissues of the orbit behind the orbital septum.

Frequently, there is mild to severe restriction of

Orbital cellulitis may or may not progress to a

the ocular movements.

subperiosteal abscess or orbital abscess.

Fundus examination may show congestion of

retinal veins and signs of papillitis or papilloedema.

Etiology

Orbits may be infected by following modes:

Complications

1. Exogenous infection. It may result from

These are quite common if not treated promptly.

penetrating injury especially when associated with

1. Ocular complications are usually blinding and

retention of intraorbital foreign body, and

include exposure keratopathy, optic neuritis and

following operations like evisceration, enucleation,

central retinal artery occlusion.

dacryocystectomy and orbitotomy.

2. Extension of infection from neighbouring

structures. These include paranasal sinuses, teeth,

face, lids, intracranial cavity and intraorbital

structures. It is the commonest mode of orbital

infections.

3. Endogenous infection. It may rarely develop as

metastatic infection from breast abscess, puerperal

sepsis, thrombophlebitis of legs and septicaemia.

Causative organisms. Those commonly involved

are: Streptococcus pneumoniae, Staphylococcus

aureus, Streptococcus pyogenes and Haemophilus

influenzae.

Pathology

Pathological features of orbital cellulitis are similar to

suppurative inflammations of the body in general,

Fig. 16.7. Orbital cellulitis in a three-year-old female child.

except that: (i) due to the absence of a lymphatic

386

Comprehensive OPHTHALMOLOGY

2. Orbital complications are progression of orbital

2. Analgesic and anti-inflammatory drugs are helpful

cellulitis into subperiosteal abscess and/or orbital

in controlling pain and fever.

abscess:

3. Surgical intervention. Its indications include

i. Subperiosteal abscess is collection of purulent

unresponsiveness to antibiotics, decreasing

material between the orbital bony wall and

vision and presence of an orbital or subperiosteal

periosteum, most frequently located along the

abscess.

medial orbital wall. Clinically, subperiosteal

Techniques

abscess is suspected when clinical features of

A free incision should be made into the

orbital cellulitis are associated with eccentric

abscess when it points under the skin or

proptosis; but the diagnosis is confirmed by CT

conjunctiva.

scan.

ii. Subperiosteal abscess is drained by a 2-3 cm

ii. Orbital abscess is collection of pus within the

curved incision in the upper medial aspect.

orbital soft tissue. Clinically it is suspected by

iii. In most cases it is necessary to drain both

signs of severe proptosis, marked chemosis,

the orbit as well as the infected paranasal

complete ophthalmoplegia, and pus points below

sinuses.

the conjunctiva, but is confirmed by CT scan.

3. Temporal or parotid abcsesses may occur due to

ORBITAL MUCORMYCOSIS

spread of infection around the orbit.

Etiology. It is a severe fungal infection of the orbit.

4. Intracranial complications include cavernous

The most common fungal genera causing

sinus thrombosis, meningitis and brain abscesses.

phacomycosis are Mucor (mucormycosis) and

5. General septicemia or pyaemia may occur

Rhizopus. Infection usually begins in the sinuses and

eventually in few cases.

erodes into the orbital cavity. The organisms have a

Investigations

tendency to invade vessels and cause ischemic

1. Bacterial cultures should be performed from nasal

necrosis. A necrotizing reaction destroys muscles,

and conjunctival swabs and blood samples.

bone and soft tissue, frequently without causing signs

2. Complete haemogram may reveal leukocytosis.

of orbital cellulitis.

3. X-ray PNS to identify associated sinusitis.

Clinical features. The patients prone to such

4. Orbital ultrasonography to detect intra-orbital

infections are diabetics and immuno-compromised

abscess.

such as those with renal failure, malignant tumours

5. CT scan and MRI are useful:

and those on antimetabolite or steroid therapy; so

in differentiating between preseptal and

most of the patients are serously ill and present with

postseptal cellulitis;

Pain and proptosis, and

in detecting subperiosteal abscesses and

Necrotic areas with black eschar formation may

orbital abscesses.

be seen on the mucosa of palate, turbinates and

in detecting intracranial extension;

nasal septum and skin of eyelids (Fig. 16.8).

in deciding when and from where to drain an

Complications. If not treated energetically, patient

orbital abscess.

develops meningitis, brain abscess and dies within

Treatment

days to weeks.

1. Intensive antibiotic therapy to overcome the

Diagnosis is made clinically and confirmed by biopsy

infection. After obtaining nasal, conjunctival and

of the involved area and finding of nonseptate broad

blood culture samples, intravenous antibiotics

branching hyphae.

should be administered. For staphylococcal

Treatment is often difficult and inadequate.

infections high doses of penicillinase-resistant

Therefore, recurrences are common. Treatment

antibiotic (e.g., oxacillin) combined with ampicillin

includes:

should be given. To cover H. influenzae

especially in children, chloramphenicol or

correction of underlying disease, if possible;

clavulanic acid should also be added. Cefotaxime,

surgical excision of the involved tissue; and

ciprofloxacin or vancomycin may be used

intravenous amphotericin B or other appropriate

alternative to oxacillin and penicillin combination.

antifungal drug.

DISEASES OF ORBIT

387

CAVERNOUS SINUS THROMBOSIS

Septic thrombosis of the cavernous sinus is a

disastrous sequela, resulting from spread of sepsis

travelling along its tributaries.

Communications of cavernous sinus and sources

of infection (Fig. 16.9 A & B)

1. Anteriorly, the superior and inferior ophthalmic

veins drain in the sinus. These veins receive

blood from face, nose, paranasal sinuses and

orbits, Therefore, infection to cavernous sinus

may spread from infected facial wounds, eryseplas,

squeezing of stye, furuncles, orbital cellulitis and

sinusitis.

2. Posteriorly, the superior and inferior petrosal

Fig. 16.8. Areas of black ischar and necrosis on the

sinuses leave it to join the lateral sinus.

eyelids in a patient with rhino-orbital mucormycosis.

Labyrinthine veins opening into the inferior

petrosal sinuses bring infections from the middle

Exentration may be required in severe

ear. Mastoid emissary veins may spread infection

unresponsive cases.

from the mastoid air cells.

ORBITAL PERIOSTITIS

3. Superiorly, the cavernous sinus communicates

Orbital periostitis, i.e., inflammation of the periorbita

with veins of the cerebrum and may be infected

is not very common. It may rarely involve the

from meningitis and cerebral abscesses.

surrounding bones producing orbital osteoperiostitis.

4. Inferiorly, the sinus communicates with pterygoid

Etiology. It may result from injuries or as an extension

venous plexus.

of infection from the surrounding structures (similar

5. Medially, the two cavernous sinuses are

to orbital cellulitis). Tubercular periostitis is known

connected with each other by transverse sinuses

in children and syphilitic in adults.

which account for transfer of infection from one

side to the other.

Clinical picture. It may present in two forms:

1. Anterior orbital periostitis. It involves the orbital

Clinical picture

margin and is characterised by severe pain,

Cavernous sinus thrombosis starts initially as a

tenderness and swelling of the inflamed area.

unilateral condition, which soon becomes bilateral in

Subperiosteal abscess, when formed, frequently

more than 50 percent of cases due to intercavernous

bursts on the skin surface. Tubercular anterior

communication. The condition is characterised by

orbital periostitis usually manifests as non-healing

general and ocular features.

fistula.

2. Posterior

(deep) periostitis. It is characterised

General features. Patient is seriously ill having high

by deep-seated orbital pain, mild to moderate

grade fever with rigors, vomiting and headache.

proptosis and slight limitation of ocular

Ocular features. Patient develops:

movements. When the orbital apex is implicated

Severe pain in the eye and forehead on the

in addition, the typical picture of ‘orbital apex

affected side.

syndrome’ is also produced. It is characterised

Conjunctiva is swollen and congested.

by a triad of: (i) ophthalmoplegia due to paresis

Proptosis develops rapidly.

of third, fourth and sixth cranial nerves;

(ii)

Palsy of third, fourth and sixth cranial nerves

anaesthesia in the region of supply of ophthalmic

occurs frequently.

division of fifth nerve; and (iii) amaurosis due to

Oedema in mastoid region is a pathognomonic

involvement of optic nerve.

sign. It is due to back pressure in the mastoid

Treatment. It is on the lines of orbital cellulitis.

emissary vein.

DISEASES OF ORBIT

389

Table 16.1. Differential diagnosis of acute inflammatory proptosis

Clinical

Cavernous sinus

Orbital cellulitis

Panophthalmitis

features

thrombosis

Laterality

Initially unilateral, but soon

Unilateral

becomes bilateral

Degree of proptosis

Moderate

Marked

Moderate

Vision

Not affected in early

Complete loss of vision

stage

from the beginning

Cornea and anterior

Clear in early stages

Hazy due to corneal

chamber

oedema. Pus in the

anterior chamber

Ocular movements

Complete limitation to palsy

Marked limitation

Painful and limited

Oedema in mastoid region Present

Absent

General symptoms

Marked

Mild

with fever, and

prostrations

SPECIFIC CHRONIC ORBITAL INFLAMMATIONS

These include: foreign body granuloma, orbital

sarcoidosis, orbital vasculitis, Wegener’s

granulomatosis, specific granulomatous inflammation

caused by tuberculosis, syphilis, fungi, viruses,

parasites, leaking dermoid cyst, polyarteritis nodosa

and so on. At one time or another all these conditions

were diagnosed as pseudotumours.

IDIOPATHIC ORBITAL INFLAMMATORY

DISEASE (PSEUDOTUMOURS)

The term ‘pseudotumour’ was coined for those

conditions of the orbit which clinically presented as

tumours but histopathologically proved to be chronic

inflammations. However, recently, the use of this term

Fig. 16.10. Pseudotumour involving the right orbit.

has been restricted for an idiopathic localized

inflammatory disease consisting principally of a

Swelling or puffiness of the eyelids, proptosis,

lymphocytic infiltration associated with a

orbital pain, restricted ocular movements, diplopia,

polymorphonuclear cellular response and a

chemosis and redness.

Most cases are unilateral, although both sides

fibrovascular tissue reaction that has a variable but

may be involved occasionally.

self-limiting course. Presently, idiopathic orbital

The condition typically affects individuals

inflammatory disease (IOID) is a term being preferred

between 40 and 50 years; however, age is no bar.

to denote this condition.

Spontaneous remissions after a few weeks are

Clinical features (Fig. 16.10): Pseudotumour can

known in pseudotumour.

occur throughout the orbit from the region of lacrimal

Recurrences are also common. In some patients

gland to the orbital apex and thus produce varied

severe prolonged inflammation may cause

clinical presentations. The most commonly noted

progressive fibrosis of the orbital tissues leading

features are:

to a frozen orbit with visual impairment.

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Comprehensive OPHTHALMOLOGY

Diagnosis. Clinically pseudotumour is suspected

various tissues of the orbit results in eyelid oedema,

only by exclusion of the known conditions.

chemosis, proptosis, thickening of extraocular

Ultrasonic and CT-scanning show a diffuse

muscles and other signs of thyroid ophthalmopathy.

infiltrative lesion with irregular ill-defined margins

Most data presently support the postulate that the

and variable density.

orbital fibroblast is the primary target of inflammatory

Fine-needle aspiration biopsy may give

attack, with extraocular muscles being secondarily

histological clue.

involved. The following scheme for the pathogenesis

Incisional biopsy may be needed to confirm the

of Graves’ ophthalmopathy has been recently

diagnosis.

proposed:

Circulating T cells in patients with Graves’ disease

Treatment. It consists of a course of systemic

directed against an antigen on thyroid follicular

corticosteroids (60-80 mg of prednisolone per day

cells, recognize this antigen on orbital and pretibial

for 2 weeks, initially and then gradually tapered).

fibroblasts (and perhaps extraocular myocytes).

Usually, more than half of the patients show a positive

How these lymphocytes came to be directed

response. In non-responsive patients, radiotherapy

against a self-antigen, escaping deletion by the

is usually effective. A few recalcitrant cases may

immune system, is unknown.

require treatment with cytotoxic agents.

The T cells then infiltrate the orbit and pretibial

skin. An interaction between the activated CD4 T

cells and local fibroblasts results in the release of

GRAVES’ OPHTHALMOPATHY

cytokines into the surrounding tissue

- in

particular, interferon-interleukin-1, and tumor

This term is coined to denote typical ocular changes

necrosis factor.

which include lid retraction, lid lag, and proptosis.

These or other cytokines then stimulate the

These changes have also been labelled as : endocrine

expression of immunomodulatory proteins (the

exophthalmos, malignant exophthalmos, dysthyroid

72-kd heat-shock protein, intercellular adhesion

ophthalmopathy, ocular Graves’ disease (OGD), and

molecules, and HLA-DR) in orbital fibroblasts,

thyroid eye disease (TED).

thus perpetuating the autoimmune response in

Etiology

the orbital connective tissue.

Furthermore, particular cytokines

(interferon-,

It may be a part of Graves’ disease (the syndrome

interleukin-1, transforming growth factor, and

consisting of hyperthyroidism, goitre and eye signs)

insulin-like growth factor

1) stimulate

or may be associated with hypothyroidism or even

glycosaminoglycan production in fibroblasts,

euthyroidism. Thus, a direct causative connection

proliferation of fibroblasts, or both, leading to the

between the thyroid dysfunction and the ocular

accumulation of glycosaminoglycans and oedema

changes remains elusive. There is an increasing

in the orbital connective tissue. In addition,

evidence to suggest that Graves’ ophthalmopathy

thyrotropin-receptor or other antibodies may have

has an autoimmune etiology.

direct biological effects on orbital fibroblasts or

Pathogenesis

myocytes; alternatively, these antibodies may

The histopathologic reaction of various tissues is

reflect the on going autoimmune process.

dominated by a mononuclear cell inflammatory

The increase in connective-tissue volume and

reaction, which is characteristic of, but by no means

the fibrotic restriction of extraocular-muscle

limited to, an immunologically-mediated disease

movement resulting from fibroblast stimulation

mechanism. Deposition of glycosaminoglycans

lead to the clinical manifestations of

(GAGs) such as hyaluronic acid together with

ophthalmopathy. A similar process occurring in

interstitial oedema and inflammatory cells are

the pretibial skin results in the expansion of

considered to be the causes of swelling of various

dermal connective tissue, which in turn leads to

tissues in the orbit and dysfunction of extraocular

the nodular or diffuse skin thickening

muscles in thyroid ophthalmopathy. Swelling of the

characteristic of pretibial dermopathy.

DISEASES OF ORBIT

391

Clinical features (Fig. 16.11)

sensation, lacrimation and photophobia. Corneal

1. Lid signs. These are:

exposure has been attributed to upper lid

Retraction of the upper lids producing the

retraction, exophthalmos, lagophthalmos, inability

characteristic staring and frightened appearance

to elevate the eyes and a decreased blink rate.

(Dalrymple’s sign);

7. Optic neuropathy. It occurs due to direct

Lid lag (von Graefe’s sign) i.e., when globe is

compression of the nerve or its blood supply by

moved downward, the upper lid lags behind;

the enlarged rectus muscles at the orbital apex. It

Fullness of eyelids due to puffy oedematous

may manifest as papilloedema or optic atrophy

swelling (Enroth’s sign);

with associated slowly progressive impairment of

Difficulty in eversion of upper lid (Gifford’s sign);

vision.

Infrequent blinking (Stellwag’s sign).

Classification

American Thyroid Association (ATA) has classified

Graves’ ophthalmopathy, irrespective of the hormonal

status into following classes, characterised by the

acronym ‘NOSPECS’.

Class 0

: No signs and symptoms.

Class 1

: Only signs, no symptoms (signs are

limited to lid retraction, with or without

lid lag and mild proptosis).

Class 2

: Soft tissue involvement with signs (as

described in Class-1) and symptoms

including lacrimation, photophobia, lid

or conjunctival swelling.

Class 3

: Proptosis is well established.

Fig. 16.11. A patient with Graves’ ophthalmopathy having

bilateral exophthalmos and lid retraction.

Class 4

: Extraocular muscle involvement

(limitation of movement and diplopia).

2. Conjunctival signs. These include ‘deep injection’

Class 5

: Corneal involvement

(exposure

and ‘chemosis’.

keratitis).

3. Pupillary signs. These are of less importance

Class 6

: Sight loss due to optic nerve

and may be evident as inequality of dilatation of

involvement with disc pallor or

pupils.

papilloedema and visual field defects.

4. Ocular motility defects. These range from

For practical purposes it has been described as ‘early’

convergence weakness (Mobius’s sign) to partial

(which include ATA Class 1 & 2) and ‘Late Graves’

or complete immobility of one or all of the extrinsic

ophthalmopathy’ (Class 3 to 6).

ocular muscles. The most common ocular motility

Clinical types

defect is a unilateral elevator palsy caused by an

involvement of the inferior rectus muscle followed

1. Thyrotoxic exophthalmos (Exophthalmic goitre):

by failure of abduction due to involvement of

In this form a mild exophthalmos is associated with

medial rectus muscle.

lid signs and all signs of thyrotoxicosis which include

5. Exophthalmos. It is a common and classical sign

tachycardia, muscular tremors, and raised basal

of the disease. As a rule both eyes are

metabolism. Graves’ disease is the commonest variety

symmetrically affected; but it is frequent to find

of hyperthyroid state. It typically affects the women

one eye being more porminent than the other.

between 20 and 45 years of age.

Even unilateral proptosis is not uncommon. In

2. Thyrotropic exophthalmos (exophthalmic

majority of cases it is self-limiting.

ophthalmoplegia). In this clinical variety, an extreme

6. Exposure keratitis and symptoms of ocular

exophthalmos and external ophthalmoplegia (due to

surface discomfort. These include sandy or gritty

infiltrative thyroid ophthalmopathy) are associated

392

Comprehensive OPHTHALMOLOGY

with euthyroidism or hypothyroidism. The condition

4. Radiotherapy

(2000 rads given over

10 days

usually affect middle-aged persons, and runs a self-

period). It may help in reducing orbital oedema

limiting course characterised by remissions and

in patients where steroids are contraindicated.

relapses. Some prefer to use the term ocular Graves’

5. Lateral tarsorrhaphy should be performed in

disease (OGD) for this entity.

patients with exposure keratopathy (with mild to

moderate proptosis) not responding to topical

Differential diagnosis

artificial tears.

Clinical diagnosis is not difficult in advanced cases

6. Extraocular muscle surgery. It should be carried

of Graves’ ophthalmopathy with bilateral proptosis.

out for left-out diplopia in primary gaze, after the

However, early cases having unilateral proptosis need

congestive phase of disease is over and the

to be differentiated from other causes of unilateral

angle of deviation is constant for the last

proptosis of adulthood onset.

months.

7. Surgical orbital decompression. It should be

Investigations

performed only when systemic steroids and

1. Thyroid function tests. These should include:

radiotherapy have proved ineffective in patients

serum T3, T4, TSH and estimation of radioactive

with marked proptosis associated with severe

iodine uptake.

exposure keratopathy and/or optic neuropathy

2. Positional tonometry. An increase in intra-ocular

with imminent danger of permanent visual loss.

pressure in upgaze helps in diagnosis of

The most commonly employed technique is

subclinical cases.

‘two wall decompression’ in which part of the

3. Ultrasonography. It can detect changes in

orbital floor and medial wall are removed.

extraocular muscles even in class 0 and class 1

8. Cosmetic surgery for persistent lid retraction. It

cases and thus helps in early diagnosis. In

consists of levator and Muller’s muscle recession.

addition to the increase in muscle thickness,

Recently, implantation of scleral grafts has become

erosion of temporal wall of orbit, accentuation of

a popular technique.

retrobulbar fat and perineural inflammation of

9. Blepharoplasty. It may be performed by removal

optic nerve can also be demonstrated in some

of excess fatty tissue and redundant skin from

early cases.

around the eyelids.

4. Computerised tomographic scanning. It may

show proptosis, muscle thickness, thickening of

optic nerve and anterior prolapse of the orbital

ORBITAL TUMOURS

septum (due to excessive orbital fat and/or muscle

swelling).

Orbital tumours are not very common. These include

Management of Graves’ ophthalmopathy

primary, secondary and metastatic tumours.

(A) Primary tumours. Those arising from the

It is in addition to and independent of the therapy for

various orbital structures are as follows:

the associated thyroid dysfunction; as the latter

usually does not alter the course of ophthalmic

Developmental tumours: Dermoid, epidermoid,

lipodermoid and teratoma.

features. The treatment modalities employed are as

Vascular tumours: Haemangioma and

follows:

1. Topical artificial tear drops in the day time and

lymphangioma.

ointment at bed time are useful for relief of

Adipose tissue tumours: Liposarcoma

foreign body sensation and other symptoms of

Fibrous tissue tumours: Fibroma, fibrosarcoma

ocular surface drying.

and fibromatosis.

2. Guanethidine 5% eyedrops may decrease the lid

Osseous and cartilaginous tumours: Osteoma,

retraction caused by overaction of Muller’s

chondroma, osteoblastoma, osteogenic sarcoma

muscle.

after irradiation, fibrous dysplasia of bone, and

3. Systemic steroids may be indicated in acutely

Ewing’s sarcoma.

inflamed orbit with rapidly progressive chemosis

Myomatous tumours: Rhabdomyoma, leomyoma

and proptosis with or without optic neuropathy.

and rhabdomyosarcoma.

DISEASES OF ORBIT

393

Tumours of optic nerve and its sheaths: Glioma

Treatment is surgical excision. Care should be

and meningioma.

taken not to leave behind the contents of cyst which

Tumours of lacrimal gland: Benign mixed

are potentially irritating.

tumour, malignant mixed tumours and lymphoid

2. Epidermoid. It is composed of epidermis without

tumours.

any epidermal appendages in the wall of the cyst.

Tumours of lymphocytic tissue: Benign and

These are almost always cystic. The cyst wall

malignant lymphomas.

contains keratin debris. Treatment is surgical excision.

10. Histiocytosis-X.

3. Lipodermoids. These are solid tumours usually

seen beneath the conjunctiva. These are mostly

(B) Secondary tumours, spreading from

located adjacent to the superior temporal quadrant of

surrounding structures.

the globe (Fig. 16.13). These do not require any

surgical intervention unless they enlarge

tumours.

significantly. Also see page 86.

(A) PRIMARY ORBITAL TUMOURS

I. Developmental tumours

1. Dermoids. These are common developmental

tumours which arise from an embryonic displacement

of the epidermis to a subcutaneous location. The

cystic component is lined with keratinizing epithelium

and may contain one or more dermal adnexal

structures such as hair follicles and sebaceous glands.

Dermoids are of two types:

(a) Simple dermoid. It is seen in infancy. Appears

as a firm, round, localised lesion in the upper

temporal or upper nasal aspect of the orbit.

These do not extend deep into the orbit and are

Fig. 16.13. Lipodermoid.

not associated with bony defects. Displacement

of globe is also not seen as these are located

4. Teratomas (Fig. 16.14). These are composed of

anterior to the orbital septum (Fig. 16.12).

ectoderm, mesoderm and endoderm. These may be

(b) Complicated dermoids. These are present in

solid, cystic or a mixture of both. The cystic form is

adolescence with proptosis or a mass lesion

more prevalent. Most of these are benign but some

having indistinct posterior margins

(as they

solid tumours in newborns are malignant.

arise from deeper sites). They may be associated

Exenteration is usually performed for solid tumours

with bony defects.

to effect a permanent cure. Cystic tumours may be

excised without removing the eyeball.

II. Vascular tumours

These are the most common primary benign tumours

of the orbit. These can be either haemangiomas or

lymphangiomas. Haemangiomas are further divided

into two types — capillary and cavernous.

1. Capillary haemangioma. It is commonly seen at

birth or during the first month. It appears as periocular

swelling in the anterior part of the orbit. It tends to

increase in size on straining or crying. This tumour

may initially grow in size followed by stabilization

Fig. 16.12. Dermoid right orbit.

and then regression and disappearance.

394

Comprehensive OPHTHALMOLOGY

Fig. 16.14. Congenital teratoma.

Fig. 16.15. Massive proptosis due to rhabdomyosar-

coma located in the superonasal quadrant (mimmicking

acute inflammatory process).

Treatment. These tumours usually do not require any

treatment. Indications for treatment are: optic nerve

compression, exposure keratitis, ocular dysfunction

The clinical presentation mimics an inflammatory

or cosmetic blemish. Mode of therapy are: systemic

process. The tumour commonly involves the

and/or intralesional steroids, low-dose superificial

superionasal quadrant; but may invade any part of

radiations, surgery and cryotherapy.

the orbit.

2. Cavernous haemangioma. It is the commonest

Diagnosis. The clinical suspicion is supported by X-

benign orbital tumour among adults. The tumour is

rays showing bone destruction and CT scan

usually located in the retrobulbar muscle cone. So, it

demonstrating tumour in relation to an extraocular

presents as a slowly progressing unilateral axial

muscle. Diagnosis is confirmed by biopsy.

proptosis in the second to fourth decade. It may

Treatment. High dose radiation therapy (5000 rads

occasionally compress the optic nerve without

in 5 weeks) combined with systemic chemotherapy is

causing proptosis.

very effective. Chemotherapy regime consists of

Treatment. Surgical excision of the tumour is

Vincristine 2 mg/m² on day 1 and 5, actinomycin-D

undertaken via lateral orbitotomy approach. Since the

0.015 mg/kg IV once a day for 5 days and

tumour is well encapsulated, complete removal is

cyclophosphamide 10 mg/kg once a day for 3 days;

generally possible.

to be repeated every 4 weeks for a period of 2 years.

3. Lymphangioma. It is an uncommon tumour

Exenteration is required in a few unresponsive

presenting with slowly progressive proptosis in a

patients.

young person. It often enlarges because of

spontaneous bleed within the vascular spaces, leading

IV. Tumours of the optic nerve and its meninges

to formation of ‘chocolate cysts’ which may regress

1. Optic nerve glioma. It is a benign tumour arising

spontaneously.

from the astrocytes. It usually occurs in first decade

III. Myomatous tumours

of life. It may present either as a solitary tumour or as

a part of von Recklinghausen’s neurofibromatosis

Rhabdomyosarcoma. It is a highly malignant tumour

(55%).

of the orbit arising from the extraocular muscles. It is

the most common primary orbital tumour among

Clinical features. It is characterised by early visual

children, usually occurring below the age of 15 years

loss associated with a gradual, painless, unilateral

(90%).

axial proptosis occurring in a child usually between 4

Clinical features. It classically presents as rapidly

and 8 years of age (Fig. 16.16A). Fundus examination

progressive proptosis of sudden onset in a child of

may show optic atrophy (more common) or

7-8 years (Fig. 16.15). Massive proptosis due to

papilloedema and venous engorgement. Intracranial

rhabdomyosarcoma located in the superonasal

extension of the glioma through optic canal is not

quadrant (mimmicking acute inflammatory process).

uncommon.

DISEASES OF ORBIT

395

Diagnosis. Clinical diagnosis well supported by X-

orbit are of two types: primary and secondary.

rays showing uniform regular rounded enlargement

(a) Primary intraorbital meningiomas. These are

of optic foramen in 90 percent of cases (Fig. 16.16B)

also known as ‘optic nerve sheath meningiomas’.

and CT scan and ultrasonography depicting a

These produce early visual loss associated with

fusiform growth in relation to optic nerve (Fig. 16.16

limitation of ocular movements, optic disc oedema or

C & D).

atrophy, and a slowly progressive unilateral proptosis.

Treatment. It consists of excision of the tumour mass

During the intradural stage, it is clinically

with preservation of the eyeball, by lateral orbitotomy

indistinguishable from optic nerve glioma. However,

when the cosmetically unacceptable proptosis is

the presence of opticociliary shunt is pathognomonic

present in a blind eye (due to optic atrophy). Tumours

of an optic nerve sheath meningioma.

with intracranial extensions are dealt with the

(b) Secondary orbital meningiomas. Those

neurosurgeons. In unoperable cases, radiotherapy

intracranial meningiomas which secondarily invade

should be given.

the orbit either arise from the sphenoid bone or

2. Meningiomas. These are invasive tumours arising

involve it en route to the orbit. Orbital invasion may

from the arachnoidal villi. Meningiomas invading the

occur through : floor of anterior cranial fossa, superior

Fig. 16.16. Optic nerve glioma : A, clinical photograph; B, X-rays optic foramina; C. CT scan; D, ultrasonography B scan.

396

Comprehensive OPHTHALMOLOGY

orbital fissure and optic canal. Meningioma enplaque,

affecting the greater and lesser wings of sphenoid

and taking origin in the region of pterion, is the most

common variety affecting the orbit secondarily. These

tumours typically occur in middle- aged women.

Clinical features. These are characterised by greater

proptosis and lesser visual impairment than the

primary intraorbital meningiomas. Other characteristic

features of these tumours are boggy eyelid swelling

and an ipsilateral swelling in the temporal region of

the face, especially when the intracranial tumour

arises from the lateral part of sphenoid ridge (Fig.

16.17A). In such cases proptosis is due to

hyperostosis on the lateral wall and roof of the orbit.

CT scan is very useful in assessing the extent of

tumour (Figs. 16.17 B & C).

Management of secondary orbital meningiomas is

the domain of neurosurgeons.

V. Lymphomas

These are malignant tumours of lymphoreticular

origin. Clinically and pathologically, these are quite

heterogeneous. Broadly, these can be classified in

two distinct clinico-pathologic groups: Hodgkin’s

lymphomas (HL) and non-Hodgkin’s lymphomas

(NHL). Both groups include many histopathologic

subtypes. Orbits are involved more commonly by

non-Hodgkin’s lymphomas.

Clinical features. These may involve orbit, lacrimal

glands, lids and subconjunctival tissue and produce

varied clinical features.

Diagnosis. In case of suspected orbital lymphoma,

an incisional needle aspiration biopsy should be

carried out. On getting histopathologic evidence of

lymphoma, a thorough systemic evaluation including

search for lymph nodes, peripheral blood picture,

bone marrow examination, chest X-rays, serum

Fig. 16.17. Secondary orbital involvement in a patient

immunoprotein electrophoresis, lymphangiography

with sphenoidal ridge meningioma, clinical photograph:

(A) CT scan, coronal (B) and axial

and even a whole body CT scan should be carried

out to establish systemic involvement.

VI. Histiocytosis-X

Treatment. Most of the lymphocytic tumours are

This is a group of diseases characterised by an

radiosensitive and thus in cases without

idiopathic abnormal proliferation of histiocytes with

dissemination radiotherapy (4000 rads in 4 weeks) is

granuloma formation. These diseases primarily affect

the best treatment. Chemotherapy is recommended

children with an orbital involvement in 20 per cent of

in cases with dissemination.

cases. This group includes following three diseases:

DISEASES OF ORBIT

397

1. Hand-Schuller-Christian disease. It is a chronic

ORBITAL BLOW-OUT FRACTURES

disseminated form of histiocytosis involving both soft

tissues and bones in older children of either sex. It is

These are isolated comminuted fractures which occur

characterised by a triad of proptosis, diabetes

when the orbital walls are pressed indirectly, ‘Blow-

insipidus and bony defects in the skull.

out fractures’ mainly involve orbital floor and medial

2. Letterer-Siwe disease. It is systemic form of

wall.

histiocytosis-X characterised by widespread soft

tissue and visceral involvement with or without bony

Etiology

changes. The disease has a slight male preponderance

Blow-out orbital fractures generally result from

and often occurs in the first three years of life. Orbital

trauma to the orbit by a relatively large, often rounded

involvement is comparatively rare.

object, such as tennis ball, cricket ball, human fist

3. Eosinophilic granuloma. It is characterised by a

(Fig. 16.18) or part of an automobile. The force of the

solitary or multiple granulomas involving the bones.

blow causes a backward displacement of the eye and

The disease occurs in elder children and frequently

an increase in intraorbital pressure; with a resultant

involves the orbital bones.

fracture of the weakest point of the orbital wall.

Usually this point is the orbital floor, but this may be

(B) SECONDARY ORBITAL TUMOURS

the medial wall also.

These may arise from the following structures:

1. Tumours of eyeball: retinoblastoma (Fig. 11.36)

and malignant melanoma (Fig. 7.24).

2. Tumours of the eyelids: squamous cell carcinoma

and basal cell carcinoma.

3. Tumours of nose and paranasal sinuses: These

tumours very commonly involve the orbit (50%).

These include:carcinomas, sarcomas and

osteomas.

4. Tumours of nasopharynx. Carcinoma of

nasopharynx is the commonest tumour involving

the orbit. Thirty-eight percent cases with this

tumour show ophthalmoneurological symptoms

which include proptosis and involvement of fifth

Fig. 16.18. Mechanism of blow-out-fracture

and sixth cranial nerves. Rarely, third, fourth and

of the orbital floor.

second cranial nerves are also involved.

5. Tumours of cranial cavity invading orbit are

Classification

glioma and meningioma.

1. Pure blow-out fractures: These are not associated

with involvement of the orbital rim.

2. Impure blow-out fractures: These are associated

These involve the orbit by haematogenous spread

with other fractures about the middle third of the

from a distant primary focus and include the following:

facial skeleton.

1. Neuroblastoma — from adrenals and sympathetic

Clinical features

chain.

1. Periorbital oedema and blood extravasation in

2. Nephroblastoma —from kidneys.

and around the orbit (such as subconjunctival

3. Carcinoma — from lungs, breast, prostate, thyroid

ecchymosis) occur immediately. This may mask

and rectum.

certain signs and symptoms seen later.

4. Malignant melanoma — from skin.

2. Emphysema of the eyelids occurs more frequently

5. Ewing’s sarcoma —from the bones.

with medial wall than floor fractures. It may be

6. Leukaemic infiltration.

made worse by blowing of nose.

398

Comprehensive OPHTHALMOLOGY

Paraesthesia and anaesthesia in the distribution

Roentgen examination

of infraorbital nerve (lower lid, cheek, side of

Plain X-rays. The most useful projection for

nose, upper lip and upper teeth) are very common.

detecting an orbital floor fracture is a nose-chin

Ipsilateral epistaxis as a result of bleeding from

(Water’s) view. The common roentgen findings

maxillary sinus into the nose is frequently noted

are : fragmentation and irregularity of the orbital

in early stages.

floor; depression of bony fragments and ‘hanging

Proptosis of variable degree may also be

drop’ opacity of the superior maxillary antrum

present initially because of the associated orbital

from orbital contents herniating through the floor

oedema and haemorrhage.

(Fig. 16.20).

Enophthalmos and mechanical ptosis. After

Computerised tomography scanning and

about

10 days, as the oedema decreases, the

magnetic resonance imaging (MRI). These are

eyeball sinks backward and somewhat inferiorly

of greater value for detailed visualisation of soft

resulting in enophthalmos and mechanical ptosis

tissues. Coronal sections are particularly useful

(Fig.

16.19). Three factors responsible for

in evaluating the extent of the fracture.

producing enophthalmos are:

escape of orbital fat into the maxillary sinus;

backward traction on the globe by entrapped

in-ferior rectus muscle; and

enlargement of the orbital cavity from displace-

ment of fragments.

Diplopia also becomes evident after the decrease

in oedema. It typically occurs in both up and

down gaze (double diplopia) due to entrapment

of soft tissue structures in the area of the blow-

out fracture. The presence of muscle restriction

can be confirmed by a positive ‘forced duction

test’.

Severe ocular damage associated with blowout

fracture is rare. This is because a

‘blow-out

Fig. 16.20. Plain X-ray orbit (AP view) showing

fracture’ is nature’s way of protecting the globe

herniated orbital contents (arrow) with blow-out

from injury. Nevertheless, the eye should be

fracture of the orbital floor.

carefully examined to exclude the possibility of

intraocular damage.

Management

Surgical repair to restore continuity of the orbital floor

may be made with or without implants. It may not be

required in many cases. The optimal time for surgery,

when indicated, is after 10-14 days of injury.

Indications of surgical intervention include:

1. Diplopia not resolving significantly in the early

days after trauma.

2. A fracture with a large herniation of tissues into

the antrum.

3. Incarceration of tissues in the fracture with

resulting globe retraction and increased

applanation tension on attempted upward gaze.

4. Enophthalmos greater than 3 mm.

Fig. 16.19. Enophthalmos and mechanical ptosis in a

Any of these factors, alone or combinedly could

patient with blow-out-fracture of orbit.

indicate that early orbital repair is necessary.

DISEASES OF ORBIT

399

ORBITAL SURGERY

ORBITOTOMY

Orbitotomy operation refers to surgical approach for

an orbital mass lesion. There are four surgical

approaches to the orbit:

1. Anterior orbitotomy. It can be performed through

the skin (transcutaneous approach) or conjunctiva

(transconjunctival approach) at a selected site near

the orbital margin and more or less directly anterior

to the lesion which is to be explored or removed.

Therefore, anterior orbitotomy is indicated only when

the lesion is readily palpable through the eyelids and

is judged to be mainly in front of the equator of

eyeball.

2. Lateral orbitotomy. In this approach lateral half of

the supraorbital margin with the quadrilateral piece

of bone forming the lateral orbital wall is temporarily

removed. This approach provides an adequate

exposure to the orbital contents and is particularly

valuable for the retrobulbar lesions. The classical

Fig. 16.21. Exenteration of the orbit : A, skin incision;

technique of lateral orbitotomy using S-shaped brow

B, periosteal reflection and C, amputation of the

skin incision is called Kronlein’s operation.

orbital contents.

3. Transfrontal orbitotomy. In this technique orbit

is opened through its roof and thus mainly the domain

EXENTERATION

of neurosurgeons. Transfrontal orbitotomy is used

It is a mutilating surgery in which all the contents of

to decompress the roof of the optic canal and to

the orbits along with the periorbita are removed

explore and to remove when possible tumours of the

through an incision made along the orbital margins

sphenoidal ridge involving the superior orbital fissure.

(Fig. 16.21). Exenteration is indicated for malignant

4. Temporofrontal orbitotomy. This approach

tumours arising from the orbital structures or

provides an access to the orbit (through its roof) and

spreading from the eyeball. Now-a-days, debulking

anterior and middle cranial fossa simultaneously.

of the orbit is preferred over exenteration.

CHAPTER

Ocular Injuries

MECHANICAL INJURIES

Thermal injuries

Extraocular foreign bodies

Blunt trauma

Electrical injuries

Perforating injuries

Perforating injuries with retained IOFB

Radiational injuries

Sympathetic ophthalmitis

NON-MECHANICAL INJURIES

Ultraviolet radiations

Chemical injuries

Infrared radiations

Acid burns

Alkali burns

Ionizing radiational injuries

Contusion. It refers to closed-globe injury

MECHANICAL INJURIES

resulting from blunt trauma. Damage may occur

at the site of impact or at a distant site.

In this era of high speed traffic and industrialization,

Lamellar laceration. It is a closed Globe injury

the incidence of injuries is increasing in general. Like

characterized by a partial thickness wound of the

any other part of the body, eyes are also not exempt

from these injuries; in spite of the fact that they are

eyewall caused by a sharp object or blunt trauma.

well protected by the lids, projected margins of the

2. Open-globe injury is associated with a full

orbit, the nose and a cushion of fat from behind.

thickness wound of the sclera or cornea or both. It

Mechanical injuries can be grouped as under:

includes rupture and laceration of eye wall.

Retained extraocular foreign bodies

i. Rupture refers to a full-thickness wound of

Blunt trauma (contusional injuries)

eyewall caused by the impact of blunt trauma.

Penetrating and perforating injuries

The wound occurs due to markedly raised

Penetrating injuries with retained intraocular

intraocular pressure by an inside-out injury

foreign bodies.

mechanism.

ii. Laceration refers to a full-thickness wound of

NEW OCULAR TRAUMA TERMINOLOGIES

eyewall caused by a sharp object. The wound

Before going into details of these mechanical injuries,

occurs at the impact site by an outside-in

it will be worthwhile to become familiar with the new

mechanism. It includes:

ocular trauma terminology system. The term eyewall

Penetrating injury refers to a single laceration

has been restricted for the outer fibrous coat (cornea

of eyewall caused by a sharp object.

and sclera) of the eyeball. The new definitions

Perforating injury refers to two full thickness

proposed by the ‘American Ocular Trauma Society’

lacerations

(one entry and one exit) of the

for mechanical ocular injuries are as follows:

eyewall caused by a sharp object or missile.

1. Closed-globe injury is one in which the eyewall

The two wounds must have been caused by

(sclera and cornea) does not have a full thickness

wound but there is intraocular damage. It includes:

the same agent.

402

Comprehensive OPHTHALMOLOGY

Intraocular foreign body injury is technically

Signs. Examination reveals marked blepharospasm

a penetrating injury associated with retained

and conjunctival congestion. A foreign body can be

intraocular foreign body. However, it is grouped

localized on the conjunctiva or cornea by oblique

separately because of different clinical

illumination. Slit-lamp examination after fluorescein

implications.

staining is the best method to discover corneal foreign

body. Double eversion of the upper lid is required to

EXTRAOCULAR FOREIGN BODIES

discover a foreign body in the superior fornix.

Extraocular foreign bodies are quite common in

Complications. Acute bacterial conjunctivitis may

industrial and agricultural workers. Even in day-to-

occur from infected foreign bodies or due to rubbing

day life, these are not uncommon.

with infected hands. A corneal foreign body may be

Common sites. A foreign body may be impacted in

complicated by ulceration. Pigmentation and/or

the conjunctiva or cornea (Fig. 17.1).

opacity may be left behind by an iron or emery

On the conjunctiva, it may be lodged in the

particles embedded in the cornea.

sulcus subtarsalis, fornices or bulbar conjunctiva.

Treatment. Extraocular foreign bodies should be

In the cornea, it is usually embedded in the

removed as early as possible.

epithelium, or superficial stroma and rarely into

Removal of conjunctival foreign body. A foreign

the deep stroma.

body lying loose in the lower fornix, sulcus

subtarsalis or in the canthi may be removed with

a swab stick or clean handkerchief even without

anaesthesia. Foreign bodies impacted in the

bulbar conjunctiva need to be removed with the

help of a hypodermic needle after topical

anaesthesia.

Removal of corneal foreign body. Eye is

anaesthetised with topical instillation of 2 to 4

percent xylocaine and the patient is made to lie

supine on an examination table. Lids are separated

with universal eye speculum, the patient is asked

to look straight upward and light is focused on

the cornea. First of all, an attempt is made to

Fig. 17.1. Foreign body on the cornea.

remove the foreign body with the help of a wet

cotton swab stick. If it fails then foreign body

Common types. The usual foreign bodies:

spud or hypodermic needle is used. Extra care is

In industrial workers are particles of iron

taken while removing a deep corneal foreign

(especially in lathe and hammer-chisel workers),

body, as it may enter the anterior chamber during

emery and coal.

manoeuvring. If such a foreign body happens to

In agriculture workers, these are husk of paddy

be magnetic, it is removed with a hand-held

and wings of insects.

magnet. After removal of foreign body, pad and

Other common foreign bodies are particles of

bandage with antibiotic eye ointment is applied

dust, sand, steel, glass, wood and small insects

for

24 to

48 hours. Antibiotic eyedrops are

(mosquitoes).

instilled 3-4 times a day for about a week.

Symptoms. A foreign body produces immediate:

Discomfort, profuse watering and redness in the

Prophylaxis. Industrial and agricultural workers

eye.

should be advised to use special protective glasses.

Pain and photophobia are more marked in corneal

Cyclists and scooterists should be advised to use

foreign body than the conjunctival.

protective plain glasses or tinted goggles. Special

Defective vision occurs when it is lodged in the

guards should be put on grinding machines and use

centre of cornea.

of tools with overhanging margins should be banned.

OCULAR INJURIES

403

Eye health care education should be imparted,

the posterior wall of the globe, the compression

especially to the industrial and agricultural workers.

waves rebound back anteriorly. This force

damages the retina and choroid by forward pull

BLUNT TRAUMA

and lens-iris diaphragm by forward thrust from

the back (Fig. 17.2D).

Modes of injury

5. Indirect force. Ocular damage may also be caused

Blunt trauma may occur following:

by the indirect forces from the bony walls and

Direct blow to the eye ball by fist, ball or blunt

elastic contents of the orbit, when globe suddenly

instruments like sticks, and big stones.

strikes against these structures.

Accidental blunt trauma to eyeball may also

occur in roadside accidents, automobile accidents,

Modes of damage

injuries by agricultural and industrial instruments/

The different forces of the blunt trauma described

machines and fall upon the projecting blunt

above may cause damage to the structures of the

objects.

globe by one or more of the following modes:

1. Mechanical tearing of the tissues of eyeball.

Mechanics of blunt trauma to eyeball

2. Damage to the tissue cells sufficient to cause

Blunt trauma of eyeball produces damage by different

disruption of their physiological activity.

forces as described below:

3. Vascular damage leading to ischaemia, oedema

1. Direct impact on the globe. It produces maximum

and haemorrhages.

damage at the point where the blow is received

4. Trophic changes due to disturbances of the

(Fig. 17.2A).

nerve supply.

2. Compression wave force. It is transmitted through

5. Delayed complications of blunt trauma such as

the fluid contents in all the directions and strikes

secondary glaucoma, haemophthalmitis, late

the angle of anterior chamber, pushes the iris-

rosette cataract and retinal detachment.

lens diaphragm posteriorly, and also strikes the

retina and choroid (Fig. 17.2B). This may cause

Traumatic lesions of blunt trauma

considerable damage. Sometimes the compression

Traumatic lesions produced by blunt trauma can be

wave may be so explosive, that maximum damage

grouped as follows:

may be produced at a point distant from the

A. Closed globe injury

actual place of impact. This is called contre-coup

B. Globe rupture

damage.

C. Extraocular lesions

3. Reflected compression wave force. After striking

the outer coats the compression waves are

A. Closed-globe injury

reflected towards the posterior pole and may

Either there is no corneal or scleral wound at all

cause foveal damage (Fig. 17.2C).

(contusion) or it is only of partial thickness (lamellar

4. Rebound compression wave force. After striking

laceration). Contusional injuries may vary in severity

Fig. 17.2. Mechanics of blunt trauma to eyeball: A, direct impact; B, compression wave force; C, reflected compression

wave; D, rebound compression wave.

404

Comprehensive OPHTHALMOLOGY

from a simple corneal abrasion to an extensive

5. Deep corneal opacity. It may result from oedema

intraocular damage. Lesions seen in closed-globe

of corneal stroma or occasionally from folds in

injury are briefly enumerated here structurewise.

the Descemet’s membrane.

I. Cornea

II. Sclera

Simple abrasions. These are very painful and

Partial thickness scleral wounds (lamellar scleral

diagnosed by fluorescein staining. These usually

lacerations) may occur alone or in association with

heal up within 24 hours with ‘pad and bandage’

other lesions of closed-globe injury.

applied after instilling antibiotic ointment.

III. Anterior chamber

Recurrent corneal erosions (recurrent keractalgia).

1. Traumatic hyphaema

(blood in the anterior

These may sometimes follow simple abrasions,

chamber). It occurs due to injury to the iris or

especially those caused by fingernail trauma.

ciliary body vessels (Fig. 17.4).

Patient usually gets recurrent attacks of acute

2. Exudates. These may collect in the anterior

pain and lacrimation on opening the eye in the

chamber following traumatic uveitis.

morning. This occurs due to abnormally loose

attachment of epithelium to the underlying

Bowman’s membrane.

Treatment. Loosely attached epithelium should be

removed by debridement and ‘pad and bandage’

applied for 48 hours, so that firm healing is

established.

Partial corneal tears (lamellar corneal laceration).

These may also follow a blunt trauma.

Blood staining of cornea. It may occur

occasionally from the associated hyphaema and

raised intraocular pressure. Cornea becomes

reddish brown (Fig. 17.3) or greenish in colour

Fig. 17.4. Photograph of a patient with hyphaema.

and in later stages simulates dislocation of the

IV. Iris, pupil and ciliary body

clear lens into the anterior chamber. It clears very

slowly from the periphery towards the centre, the

1. Traumatic miosis. It occurs initially due to

whole process may take even more than two

irritation of ciliary nerves. It may be associated

years.

with spasm of accommodation.

2. Traumatic mydriasis (Iridoplegia). It is usually

permanent and may be associated with traumatic

cycloplegia.

3. Rupture of the pupillary margin is a common

occurrence in closed-globe injury.

4. Radiating tears in the iris stroma, sometimes

reaching up to ciliary body, may occur

occasionally.

5. Iridodialysis i.e., detachment of iris from its root

at the ciliary body occurs frequently. It results in

a D-shaped pupil and a black biconvex area seen

at the periphery (Fig. 17.5).

6. Antiflexion of the iris. It refers to rotation of the

detached portion of iris, in which its posterior

surface faces anteriorly. It occurs following

Fig. 17.3. Blood staining of cornea.

extensive iridodialysis.

OCULAR INJURIES

405

may assume any of the following shapes:

Discrete subepithelial opacities are of most

common occurrence.

Early rosette cataract

(punctate). It is the

most typical form of concussion cataract. It

appears as feathery lines of opacities along

the star-shaped suture lines; usually in the

posterior cortex (Fig. 17.6).

Late rosette cataract. It develops in the

posterior cortex 1 to 2 years after the injury. Its

sutural extensions are shorter and more

compact than the early rosette cataract.

Traumatic zonular cataract. It may also occur

in some cases, though rarely.

Diffuse (total) concussion cataract. It is of

Fig. 17.5. Traumatic cataract and iridodialysis

frequent occurrence.

following contusional injury.

Early maturation of senile cataract may follow

blunt truma.

Retroflexion of the iris. This term is used when

whole of the iris is doubled back into the ciliary

region and becomes invisible.

Traumatic aniridia or iridremia. In this

condition, the completely torn iris (from ciliary

body) sinks to the bottom of anterior chamber in

the form of a minute ball.

Angle recession refers to the tear between

longitudinal and circular muscle fibres of the

ciliary body. It is characterized by deepening of

the anterior chamber and widening of the ciliary

body band on gonioscopy. Later on it is

complicated by glaucoma.

10. Inflammatory changes. These include traumatic

Fig. 17.6. Rosette-shaped cataract following blunt

iridocyclitis, haemophthalmitis, post-traumatic iris

trauma.

atrophy and pigmentary changes.

Treatment. It consists of atropine, antibiotics and

Treatment of traumatic cataract is on general lines

steroids. In the presence of ruptures of pupillary

(see pages 183-202).

margins and subluxation of lens, atropine is

3. Traumatic absorption of the lens. It may occur

contraindicated.

sometimes in young children resulting in aphakia.

4. Subluxation of the lens (Fig. 8.31A). It may occur

V. Lens

due to partial tear of zonules. The subluxated

It may show following changes:

lens is slightly displaced but still present in the

1. Vossius ring. It is a circular ring of brown pigment

pupillary area. On dilatation of the pupil its edge

seen on the anterior capsule. It occurs due to

may be seen. Depending upon the site of zonular

striking of the contracted pupillary margin against

tear subluxation may be vertical

(upward or

the crystalline lens. It is always smaller than the

downward), or lateral (nasal or temporal).

size of the pupil.

5. Dislocation of the lens. It occurs when rupture of

2. Concussion cataract. It occurs mainly due to

the zonules is complete. It may be intraocular

imbibition of aqueous and partly due to direct

(commonly) or extraocular (sometimes). Intraocular

mechanical effects of the injury on lens fibres. It

dislocation may be anterior

(into the anterior

406

Comprehensive OPHTHALMOLOGY

chamber, Fig.

8.31B) or posterior

(into the

4. Traumatic choroiditis may be seen on fundus

vitreous, Fig. 8.31C). Extraocular dislocation may

examination as patches of pigmentation and

be in the subconjunctival space (phakocele) or it

discoloration after the eye becomes silent.

may fall outside the eye.

VIII. Retina

For treatment of the subluxated or dislocated lens

Commotio retinae (Berlin’s oedema). It is of

see page 204.

common occurrence following a blow on the eye.

VI. Vitreous

It manifests as milky white cloudiness involving

1. Liquefaction and appearance of clouds of fine

a considerable area of the posterior pole with a

pigmentary opacities (a most common change).

‘cherry-red spot’ in the foveal region. It may

2. Detachment of the vitreous either anterior or

disappear after some days or may be followed by

posterior.

pigmentary changes.

3. Vitreous haemorrhage. It is of common

Retinal haemorrhages. These are quite common

occurrence (see page 246).

following concussion trauma. Multiple

4. Vitreous herniation in the anterior chamber may

haemorrhages including flame-shaped and pre-

occur with subluxation or dislocation of the lens.

retinal (subhyaloid) D-shaped haemorrhage may

VII. Choroid

be associated with traumatic retinopathy.

Rupture of the choroid. The rupture of choroid

Retinal tears. These may follow a contusion,

is concentric to the optic disc and situated

particularly in the peripheral region, especially in

temporal to it. Rupture may be single or multiple.

eyes already suffering from myopia or senile

On fundus examination, the choroidal rupture

degenerations.

looks like a whitish crescent (due to underlying

Traumatic proliferative retinopathy

(Retinitis

sclera) with fine pigmentation at its margins.

proliferans). It may occur secondary to vitreous

Retinal vessels pass over it (Fig. 17.7).

haemorrhage, forming tractional bands.

Choroidal haemorrhage may occur under the

Retinal detachment. It may follow retinal tears or

retina (subretinal) or may even enter the vitreous

vitreo-retinal tractional bands.

if retina is also torn.

Concussion changes at macula. Traumatic

Choroidal detachment is also known occur

macular oedema is usually followed by pigmentary

following blunt trauma.

degeneration. Sometimes, a macular cyst is

formed, which on rupture may be converted into

a lamellar or full thickness macular hole.

IX. Intraocular pressure changes in closed-globe

injury

1. Traumatic glaucoma. It may occur due to multiple

factors, which are described in detail on page

235.

2. Traumatic hypotony. It may follow damage to the

ciliary body and may even result in phthisis

bulbi.

X. Traumatic changes in the refraction

1. Myopia may follow ciliary spasm or rupture of

zonules or anterior shift of the lens.

2. Hypermetropia and loss of accommodation may

result from damage to the ciliary body

Fig. 17.7. Choroidal rupture following blunt trauma.

(cycloplegia).

OCULAR INJURIES

407

B. Globe rupture

PENETRATING AND PERFORATING INJURIES

Globe rupture is a full-thickness wound of the eye-

As mentioned earlier, penetrating injury is defined as

wall caused by a blunt object. Globe rupture may occur

a single full-thickness wound of the eyewall caused

in two ways:

by a sharp object. While perforating injury refers to

1. Direct rupture may occur, though rarely, at the

two full-thickness wounds (one entry and one exit)

site of injury.

of the eyewall caused by a sharp object or missile.

2. Indirect rupture is more common and occurs

These can cause severe damage to the eye and so

because of the compression force. The impact results

should be treated as serious emergencies.

in momentary increase in the intraocular pressure and

an inside-out injury at the weakest part of eyewall,

Modes of injury

i.e., in the vicinity of canal of Schlemm concentric to

1. Trauma by sharp and pointed instruments like

the limbus. The superonasal limbus is the most

needles, knives, nails, arrows, screw-drivers, pens,

common site of globe rupture (contrecoup effect—

pencils, compasses, glass pieces and so on.

the lower temporal quadrant being most exposed to

2. Trauma by foreign bodies travelling at very

trauma). Rupture of the globe may be associated with

high speed such as bullet injuries and iron foreign

prolapse of uveal tissue, vitreous loss, intraocular

bodies in lathe workers.

haemorrhage and dislocation of the lens.

Effects of penetrating/perforating injury

Treatment. A badly damaged globe should be

Damage to the ocular structures may occur by

enucleated. In less severe cases, repair should be

following effects:

done under general anaesthesia. Postoperatively

atropine, antibiotics and steroids should be used.

1. Mechanical effects of the trauma or physical

changes. These are discussed later in detail.

C. Extraocular lesions

2. Introduction of infection. Sometimes, pyogenic

Extraocular lesions caused by blunt trauma are as

organisms enter the eye during perforating

follows:

injuries, multiply there and can cause varying

1. Conjunctival lesions. Subconjunctival haemorr-

degree of infection depending upon the virulence

hage occurs very commonly. It appears as a bright

and host defence mechanism. These include: ring

red spot. Chemosis and lacerating wounds of

abscess of the cornea, sloughing of the cornea,

conjunctiva (tears) are also not uncommon.

purulent iridocyclitis, endophthalmitis or

2. Eyelid lesion. Ecchymosis of eyelids is of frequent

panophthalmitis (see pages 150-154).

occurrence. Because of loose subcutaneous tissue,

Rarely tetanus and infection by gas-forming

blood collects easily into the lids and produces ‘black-

organisms (Clostridium welchii) may also occur.

eye’. There may occur laceration and avulsion of the

lids. Traumatic ptosis may follow damage to the

3. Post-traumatic iridocyclitis. It is of frequent

levator muscle.

occurrence and if not treated properly can cause

3. Lacrimal apparatus lesions. These include

devastating damage.

dislocation of lacrimal gland and lacerations of

4. Sympathetic ophthalmitis. It is a rare but most

lacrimal passages especially the canaliculi.

dangerous complication of a perforating injury. It

4. Optic nerve injuries. These are commonly

is described separately (see page 413).

associated with fractures of the base of skull. These

Mechanical effects

may be in the form of traumatic papillitis, lacerations

of optic nerve, optic nerve sheath haemorrhage and

Mechanical effects of penetrating/perforating trauma

avulsion of the optic nerve from back of the eye.

on the different ocular structures with their

management are enumerated here briefly.

5. Orbital injury. There may occur fractures of the

orbital walls; commonest being the ‘blow-out fracture’

1. Wounds of the conjunctiva. These are common

of the orbital floor. Orbital haemorrhage may produce

and usually associated with subconjunctival

sudden proptosis. Orbital emphysema may occur

haemorrhage. A wound of more than 3 mm should be

following ethmoidal sinus rupture.

sutured.

408

Comprehensive OPHTHALMOLOGY

2. Wounds of the cornea. These can be divided into

5. A badly (severely) wounded eye. It refers to

uncomplicated and complicated wounds.

extensive corneo-scleral tears associated with

Uncomplicated corneal wounds. These are not

prolapse of the uveal tissue, lens rupture, vitreous

associated with prolapse of intraocular contents.

loss and injury to the retina and choroid. Usually

Margins of such wounds swell up and lead to

there seems to be no chance of getting useful vision

automatic sealing and restoration of the anterior

in such cases. So, preferably such eyes should be

excised.

chamber.

Treatment. A small central wound does not need

INTRAOCULAR FOREIGN BODIES

stitching. The only treatment required is pad and

Penetrating injuries with foreign bodies are not

bandage with atropine and antibiotic ointments.

infrequent. Seriousness of such injuries is

A large corneal wound (more than 2 mm) should

compounded by the retention of intraocular foreign

always be sutured.

bodies (IOFB).

ii.

Complicated corneal wounds. These are

Common foreign bodies responsible for such injuries

associated with prolapse of iris

(Fig.

17.8),

include: chips of iron and steel (90%) particles of glass,

sometimes lens matter and even vitreous.

stone, lead pellets, copper percussion caps,

Treatment. Corneal wounds with iris prolapse

aluminium, plastic and wood.

should be sutured meticulously after abscising

the iris. The prolapsed iris should never be

Modes of damage

reposited; since it may cause infection. When

A penetrating/perforating injury with retained foreign

associated with lens injury and vitreous loss,

body may damage the ocular structures by the

lensectomy and anterior vitrectomy may be

following modes:

performed along with repair of the corneal wound.

A. Mechanical effects.

B. Introduction of infection.

C. Reaction of foreign bodies.

D. Post-traumatic iridocyclitis.

E. Sympathetic ophthalmitis (see pages 413).

A. Mechanical effects

Mechanical effects depend upon the size, velocity

and type of the foreign body. Foreign bodies greater

than 2 mm in size cause extensive damage. The lesions

caused also depend upon the route of entry and the

site up to which a foreign body has travelled. In

general these include:

Corneal or/and scleral perforation, hyphaema, iris

hole;

Fig. 17.8. Corneal tear with iris prolapse.

Rupture of the lens and traumatic cataract;

Vitreous haemorrhage and/or degeneration;

3. Wounds of the sclera. These are usually associated

Choroidal perforation, haemorrhage and

with corneal wounds and should be managed as

inflammation;

above. In corneo-scleral tear, first suture should be

Retinal hole, haemorrhages, oedema and

applied at the limbus.

detachment.

4. Wounds of the lens. Extensive lens ruptures with

Locations of IOFB. Having entered the eye through

vitreous loss should be managed as above. Small

the cornea or sclera a foreign body may be retained at

wounds in the anterior capsule may seal and lead on

any of the following sites (Fig. 17.9):

to traumatic cataract; which may be in the form of a

1. Anterior chamber. In the anterior chamber, the

localised stationary cataract, early or late rosette

IOFB usually sinks at the bottom. A tiny foreign

cataract, or complete (total) cataract. These should

body may be concealed in the angle of anterior

be treated on general lines (pages 183-202).

chamber, and visualised only on gonioscopy.

OCULAR INJURIES

409

(I)

Fig. 17.9. Common sites for retention of an intraocular

foreign body: 1, anterior chamber; 2, iris; 3, lens; 4, vit-

reous; 5, retina; 6, choroid; 7, sclera; 8, orbital cavity.

2. Iris. Here the foreign body is usually entangled

in the stroma.

3. Posterior chamber. Rarely a foreign body may

sink behind the iris after entering through pupil

(II)

or after making a hole in the iris.

Fig. 17.10. Logarthmic (I) and diagrammatic (II) depiction

4. Lens. Foreign body may be present on the anterior

of routes of access of a foreign body in the vitreous,

surface or inside the lens. Either an opaque track

through: A, cornea, pupil, lens; B, cornea, iris, lens; C,

cornea, iris, zonules; D, sclera, choroid, retina.

may be seen in the lens or the lens may become

completely cataractous.

C. Reactions of the foreign body

5. Vitreous cavity. A foreign body may reach here

I Inorganic foreign body

through various routes, which are depicted below

Depending upon its chemical nature following 4 types

(Fig. 17.10):

of reactions are noted in the ocular tissues:

6. Retina, choroid and sclera. A foreign body may

1. No reaction is produced by the inert substances

obtain access to these structures through corneal

which include glass, plastic, porcelain, gold silver

route or directly from scleral perforation.

and platinum.

2. Local irritative reaction leading to encapsulation

7. Orbital cavity. A foreign body piercing the

of the foreign body occurs with lead and

eyeball may occasionally cause double perforation

aluminium particles.

and come to rest in the orbital tissues.

3. Suppurative reaction is excited by pure copper,

B. Introduction of Infection

zinc, nickel and mercury particles.

4. Specific reactions are produced by iron (Siderosis

Intraocular infection is the real danger to the eyeball.

bulbi) and copper alloys (Chalcosis):

Fortunately, small flying metallic foreign bodies are

usually sterile due to the heat generated on their

Siderosis bulbi

commission. However, pieces of the wood and stones

It refers to the degenerative changes produced by an

carry a great chance of infection. Unfortunately, once

iron foreign body. Sidesosis bulbi usually occurs after

intraocular infection is established it usually ends in

2 months to 2 years of the injury. However, earliest

endophthalmitis or even panophthalmitis.

changes have been reported after 9 days of trauma.

410

Comprehensive OPHTHALMOLOGY

Mechanism. The iron particle undergoes electrolytic

Management of retained intraocular foreign

dissociation by the current of rest and its ions are

bodies (IOFB)

disseminated throughout the eye. These ions

Diagnosis

combine with the intracellular proteins and produce

It is a matter of extreme importance particularly as the

degenerative changes. In this process, the epithelial

patient is often unaware that a particle has entered

structures of the eye are most affected.

the eye. To come to a correct diagnosis following

Clinical manifestations

steps should be taken:

1. History. A careful history about the mode of injury

1. The anterior epithelium and capsule of the lens

are involved first of all. Here, the rusty deposits

may give a clue about the type of IOFB.

are arranged radially in a ring. Eventually, the

2. Ocular examination. A thorough ocular

lens becomes cataractous.

examination with slit-lamp including gonioscopy

2. Iris. It is first stained greenish and later on turns

should be carried out. The signs which may give some

reddish brown.

indication about IOFB are: subconjunctival

3. Retina develops pigmentary degeneration which

haemorrhage, corneal scar, holes in the iris, and

resembles retinitis pigmentosa.

opaque track through the lens. With clear media,

4. Secondary open angle type of glaucoma occurs

sometimes IOFB may be seen on ophthalmoscopy in

due to degenerative changes in the trabecular

the vitreous or on the retina. IOFB lodged in the angle

meshwork.

of anterior chamber may be visualised by gonioscopy.

Chalcosis

3. Plain X-rays orbit. Antero-posterior and lateral

views are indispensable for the location of IOFB, as

It refers to the specific changes produced by the alloy

most foreign bodies are radio opaque.

of copper in the eye.

4. Localization of IOFB. Once IOFB is suspected

Mechanism. Copper ions from the alloy are

dissociated electrolytically and deposited under the

clinically and later confirmed, on fundus examination

membranous structures of the eye. Unlike iron ions

and/or X-rays, its exact localization is mandatory to

these do not enter into a chemical combination with

plan the proper removal. Following techniques may

the proteins of the cells and thus produce no

be used:

degenerative changes.

Radiographic iocialization. Before the advent

of ultrasonography and CT scan, different

Clinical manifestations

specialized radiographic techniques were used to

1. Kayser-Fleischer ring. It is a golden brown ring

localize IOFBs; which are now obsolete. However,

which occurs due to deposition of copper under

a simple limbal ring method which is still used is

peripheral parts of the Descemet’s membrane of

described below:

the cornea.

Limbal ring method. It is the most simple but

2. Sunflower cataract. It is produced by deposition

now-a-days, sparingly employed technique. A

of copper under the posterior capsule of the lens.

metallic ring of the corneal diameter (Fig. 17.11) is

It is brilliant golden green in colour and arranged

stitched at the limbus and X-rays are taken. One

like the petals of a sun flower.

exposure is taken in the anteroposterior view. In

3. Retina. It may show deposition of golden plaques

the lateral view three exposures are made one

at the posterior pole which reflect the light with

each while the patient is looking straight, upwards

a metallic sheen.

and downwards, respectively. The position of

II Reaction of organic foreign bodies

the foreign body is estimated from its relationship

The organic foreign bodies such as wood and other

with the metallic ring in different positions (Fig.

vegetative materials produce a proliferative reaction

17.12).

characterised by the formation of giant cells.

Ultrasonographic localization. It is being used

Caterpillar hair produces ophthalmia nodosum, which

increasingly these days. It can tell the position of

is characterised by a severe granulomatous

even non-radioopaque foreign bodies.

iridocyclitis with nodule formation.

OCULAR INJURIES

411

Fig. 17.11. Limbal ring used for localization of an

intraocular foreign body.

CT scan. With axial and coronal cuts, CT scan is

presently the best method of IOFB localization. It

provides cross-sectional images with a sensitivity

and specificity that are superior to plain

Fig. 17.12. Limbal ring method of radiographic localization of

radiography and ultrasonography.

IOFB: Lateral view with eyeball in straight position;

superimposed over lateral view with eyeball in down gaze.

Treatment

IOFB should always be removed, except when it is

inert and probably sterile or when little damage has

been done to the vision and the process of removal

may be risky and destroy sight (e.g., minute FB in the

retina).

Removal of magnetic IOFB is easier than the removal

of non-magnetic FB. Usually a hand-held

electromagnet (Fig. 17.13) is used for the removal of

magnetic foreign body. Method of removal depends

upon the site (location) of the IOFB as follows:

1. Foreign body in the anterior chamber. It is

removed through a corresponding corneal incision

directed straight towards the foreign body. It should

be 3 mm internal to the limbus and in the quadrant of

the cornea lying over the foreign body (Fig. 17.14).

Magnetic foreign body is removed with a hand-

held magnet. It may come out with a gush of

aqueous.

Non-magnetic foreign body is picked up with

toothless forceps.

2. Foreign body entangled in the iris tissue

(magnetic as well as non-magnetic) is removed by

performing sector iridectomy of the part containing

foreign body.

Fig. 17.13. Hand-held magnet.

412

Comprehensive OPHTHALMOLOGY

ii. Forceps removal with pars plana vitrectomy. This

technique is used to remove all non-magnetic foreign

bodies and those magnetic foreign bodies that can

not be safely removed with a magnet. In this

technique, the foreign body is removed with vitreous

forceps after performing three-pore pars plana

vitrectomy under direct visualization using an

operating microscope (Fig. 17.16).

Fig. 17.14. Removal of a magnetic intraocular foreign

body from the anterior chamber: A, the wrong incision;

B, correct incision.

3. Foreign body in the lens. Magnet extraction is

usually difficult for intralenticular foreign bodies.

Therefore, magnetic foreign body should also be

treated as non-magnetic foreign body. An

extracapsular cataract extraction (ECCE) with

intraocular lens implantation should be performed.

The foreign body may be evacuated itself along with

the lens matter or may be removed with the help of

forceps.

4. Foreign body in the vitreous and the retina is

removed by the posterior route as follows:

i. Magnetic removal. This technique is used to

remove a magnetic foreign body that can be well

localized and removed safely with a powerful magnet

without causing much damage to the intraocular

Fig. 17.15. Removal of a magnetic intraocular foreign

structures.

body from posterior segment.

An intravitreal foreign body is preferably

removed through a pars plana sclerotomy (5 mm

from the limbus) (Fig 17.15A). At the site chosen

for incision, conjunctiva is reflected and the

incision is given in the sclera concentric to the

limbus. A preplaced suture is passed and lips of

the wound are retracted. A nick is given in the

underlying pars plana part of the ciliary body. And

the foreign body is removed with the help of a

powerful hand-held electromagnet. Preplaced

suture is tied to close the scleral wound.

Conjunctiva is stitched with one or two

interrupted sutures.

For an intraretinal foreign body, the site of

incision should be as close to the foreign body

as possible (Fig. 17.15 position ‘B’). A trapdoor

scleral flap is created, the choroidal bed is treated

with diathermy, choroid is incised and foreign

body is removed with either forceps or external

Fig. 17.16. Removal of a non-magnetic foreign body

through pars plana.

magnet.

OCULAR INJURIES

413

SYMPATHETIC OPHTHALMITIS

Clinical picture

I. Exciting (injured) eye. It shows clinical features of

Sympathetic ophthalmitis is a serious bilateral

persistent low grade plastic uveitis, which include

granulomatous panuveitis which follows a penetrating

ciliary congestion, lacrimation and tenderness.

ocular trauma. The injured eye is called exciting eye

Keratic precipitates may be present at the back of

and the fellow eye which also develops uveitis is

cornea (dangerous sign).

called sympathizing eye. Very rarely, sympathetic

II. Sympathizing (sound) eye. It is usually involved

ophthalmitis can also occur following an intraocular

after 4-8 weeks of injury in the other eye. Earliest

surgery.

reported case is after 9 days of injury. Most of the

cases occur within the first year. However, delayed

Incidence

and very late cases are also reported. Sympathetic

Incidence of sympathetic ophthalmitis has

ophthalmitis, almost always, manifests as acute

tremendously decreased in the recent years due to

plastic iridocyclitis. Rarely it may manifest as

meticulous repair of the injured eye utilizing

neuroretinitis or choroiditis. Clinical picture of the

microsurgical techniques and use of the potent

iridocyclitis in sympathizing eye can be divided into

steroids.

two stages:

1. Prodromal stage. Symptoms. sensitivity to light

Etiology

(photophobia) and transient indistinctness of near

Etiology of sympathetic ophthalmitis is still not

objects (due to weakening of accommodation) are

known exactly. However, the facts related with its

the earliest symptoms.

occurrence are as follows:

Signs. In this stage the first sign may be presence of

retrolental flare and cells or the presence of a few

A. Predisposing factors

keratic precipitates (KPs) on back of cornea. Other

1. It almost always follows a penetrating wound.

signs includes mild ciliary congestion, slight

2. Wounds in the ciliary region

(the so-called

tenderness of the globe, fine vitreous haze and disc

oedema which is seen occasionally.

dangerous zone) are more prone to it.

2. Fully-developed stage. It is clinically characterised

3. Wounds with incarceration of the iris, ciliary

by typical signs and symptoms consistent with acute

body or lens capsule are more vulnerable.

plastic iridocyclitis (see page 141).

4. It is more common in children than in adults.

Treatment

5. It does not occur when actual suppuration

develops in the injured eye.

A. Prophylaxis

B. Pathogenesis. Various theories have been put

I. Early excision of the injured eye. It is the best

prophylaxis when there is no chance of saving useful

forward. Most accepted one is allergic theory, which

vision.

postulates that the uveal pigment acts as allergen

II. When there is hope of saving useful vision,

and excites plastic uveitis in the sound eye.

following steps should be taken:

Pathology

1. A meticulous repair of the wound using

microsurgical technique should be carried out,

It is characteristic of granulomatous uveitis, i.e., there

taking great care that uveal tissue is not

is nodular aggregation of lymphocytes, plasma cells,

incarcerated in the wound.

epitheloid cells and giant cells scattered throughout

2. Immediate expectant treatment with topical as

the uveal tract.

well as systemic steroids and antibiotics along

Dalen-Fuchs’ nodules are formed due to

with topical atropine should be started.

proliferation of the pigment epithelium (of the iris,

3. When the uveitis is not controlled after 2 weeks

ciliary body and choroid) associated with invasion

of expectant treatment, i.e., lacrimation,

by the lymphocytes and epitheloid cells. Retina shows

photophobia and ciliary congestion persist and if

perivascular cellular infiltration

(sympathetic

KPs appear, this eye should be excised

perivasculitis).

immediately.

414

Comprehensive OPHTHALMOLOGY

B. Treatment when sympathetic ophthalmitis has

Modes of injury

already supervened

These usually occur due to external contact with

I. If the case is seen shortly after the onset of

chemicals under following circumstances:

inflammation (i.e., during prodromal stage) in the

1. Domestic accidents, e.g., with ammonia, solvents,

sympathizing eye, and the injured eye has no useful

detergents and cosmetics.

vision, this useless eye should be excised at once.

2. Agricultural accidents, e.g., due to fertilizers,

II. Conservative treatment of sympathetic

insecticides, toxins of vegetable and animal origin.

ophthalmitis on the lines of iridocyclitis should be

3. Chemical laboratory accidents, with acids and

started immediately, as follows:

alkalies.

1. Corticosteroids should be administered by all

4. Deliberate chemical attacks, especially with acids

routes, i.e., systemic, periocular injections and

to disfigure the face.

frequent instillation of topical drops.

5. Chemical warfare injuries.

2. In severe cases, immunosuppressant drugs should

6. Self-inflicted chemical injuries are seen in

be started without delay.

malingerers and psychopaths.

3. Topical atropine should be instilled three times

Types

a day.

In general, the serious chemical burns mainly

Note. The treatment should be continued for a long

comprise alkali and acid burns.

time.

Prognosis. If sympathetic ophthalmitis is diagnosed

A. Alkali burns

early (during prodromal stage) and immediate

Alkali burns are among the most severe chemical

treatment with steroids is started, a useful vision may

injuries known to the ophthalmologists. Common

be obtained. However, in advanced cases, prognosis

alkalies responsible for burns are: lime, caustic potash

is very poor, even after the best treatment.

or caustic soda and liquid ammonia (most harmful).

Mechanisms of damage produced by alkalies

includes:

NON-MECHANICAL INJURIES

1. Alkalies dissociate and saponify fatty acids of

the cell membrane and, therefore, destroy the

CHEMICAL INJURIES

structure of cell membrane of the tissues.

2. Being hygroscopic, they extract water from the

Chemical injuries (Fig. 17.17) are by no means

cells, a factor which contributes to the total

uncommon. These vary in severity from a trivial and

necrosis.

transient irritation of little significance to complete

3. They combine with lipids of cells to form soluble

and sudden loss of vision.

compounds, which produce a condition of

softening and gelatinisation.

The above effects result in an increased deep

penetration of the alkalies into the tissues. Alkali

burns, therefore, spread widely, their action continues

for some days and their effects are difficult to

circumscribe. Hence, prognosis in such cases must

always be guarded.

Clinical picture. It can be divided into three stages:

1. Stage of acute ischaemic necrosis. In this stage;

i. Conjunctiva shows marked oedema,

congestion, widespread necrosis and a copious

purulent discharge.

ii. Cornea develops widespread sloughing of the

Fig. 17.17. A patient with chemical injury face including

epithelium, oedema and opalescence of the

eyes.

stroma.

OCULAR INJURIES

415

iii. Iris becomes violently inflamed and in severe

Table 17.1: Grades of chemical burns

cases both iris and ciliary body are replaced

Grade Changes in

Changes in

Visual

by granulation tissue.

cornea

conjunctiva

prognosis

2. Stage of reparation. In this stage conjunctival

and corneal epithelium regenerate, there occurs

Epithelial

Chemosis

Good

damage only

No ischaemia

corneal vascularization and inflammation of the

iris subsides.

II. Hazy but iris

Congestion

details visible

Chemosis

3. Stage of complications. This is characterised by

Ischaemia affecting Good

development of symblepharon, recurrent corneal

less than 1/3rd of

ulceration and development of complicated

limbal conjunctiva

cataract and secondary glaucoma.

III. Total epithelial

Ischaemia affecting Doubtful

loss, stromal

1/3rd to 1/2 of

B. Acid burns

haze and iris

limbal conjunctiva

Acid burns are less serious than alkali burns. Common

details not

acids responsible for burns are: sulphuric acid,

visible

hydrochloric acid and nitric acid.

IV. Opaque, no

Ischaemia and

Poor

Chemical effects. The strong acids cause instant

view of the iris necrosis more than

and pupil

1/2 of limbal conjunctiva

coagulation of all the proteins which then act as a

barrier and prevent deeper penetration of the acids

into the tissues. Thus, the lesions become sharply

of lime, these should be removed carefully with

demarcated.

a swab stick.

Ocular lesions

4. Removal of contaminated and necrotic tissue.

Necrosed conjunctiva should be excised.

1. Conjunctiva. There occurs immediate necrosis

Contaminated and necrosed corneal epithelium

followed by sloughing. Later on symblepharon is

should be removed with a cotton swab stick.

formed due to fibrosis.

5. Maintenance of favourable conditions for rapid

2. Cornea. It is also necrosed and sloughed out.

and uncomplicated healing by frequent application

The extent of damage depends upon the

of topical atropine, corticosteroids and antibiotics.

concentration of acid and the duration of contact.

6. Prevention of symblepharon can be done by

In severe cases, the whole cornea may slough

using a glass shell or sweeping a glass rod in the

out followed by staphyloma formation.

fornices twice daily.

Grading of chemical burns

7. Treatment of complications

Depending upon the severity of damage caused to

i. Secondary glaucoma should be treated by

the conjunctiva and cornea, the extent of chemical

topical 0.5 percent timolol instilled twice a day

burns may be graded as follows (Table 17.1):

along with oral acetazolamide 250 mg 3-4 times

Treatment of chemical burns

a day.

1. Immediate and thorough wash with the available

ii. Corneal opacity may be treated by

clean water or saline.

keratoplasty.

2. Chemical neutralization. It should be carried out

iii. Treatment of symblepharon (see page 354).

when the nature of offending chemical is known.

For example, acid burns should be neutralized

THERMAL INJURIES

with weak alkaline solutions (such as sodium

Thermal injuries are usually caused by fire, or hot

bicarbonate) and alkali burns with weak acidic

fluids. The main brunt of such injuires lies on the

solutions

(such as boric acid or mix)

lids. Conjunctiva and cornea may be affected in severe

Ethylenediamine tetra acetic acid (EDTA) 1%

cases.

solution can also be used as neutralizing agent.

Treatment for burns of lids is on general lines. When

3. Mechanical removal of contaminant. If any

cornea is affected, it should be treated with atropine,

particles are left behind, particularly in the case

steroids and antibiotics.

Ocular Therapeutics,

CHAPTER

Lasers and Cryotherapy

in Ophthalmology

OCULAR THERAPEUTICS

LASERS

Modes of administration

Production of laser beam

Antibacterial agents

Mechanisms of laser effects and their

Antiviral drugs

therapeutic applications

Ocular antifungal agents

Mydriatics and cycloplegics

CRYOTHERAPY IN OPHTHALMOLOGY

Antiglaucoma drugs

Corticosteroids

Principle

Nonsteroidal anti-inflammatory drugs

Mode of action

Viscoelastic substances

Uses

the bioavailability of the drug by increasing tissue

OCULAR THERAPEUTICS

contact time and by preventing dilution and quick

absorption. However, the drug is not available for

MODES OF ADMINISTRATION

immediate use and ointments blur the vision. These

Ocular pharmacotherapeutics can be delivered by four

are best for bedtime application or when ocular

methods: topical instillation into the conjunctival sac,

bandage is to be applied.

periocular injections, intraocular injections and

systemic administration.

ointments and do not cause much blurring of vision.

However, they are costly and difficult to prepare.

1. Topical instillation into the conjunctival sac

(d) Ocuserts. These form a system of drug delivery

This is the most commonly employed mode of

through a membrane. These can be placed in the

administration for ocular therapeutics. The drugs can

upper or lower fornix up to a week and allow a drug to

be administered topically in the form of eyedrops,

be released at a relatively constant rate. Pilocarpine

ointments, gels, ocuserts and with the help of soft

ocuserts have been found very useful in patients with

contact lenses.

primary open-angle glaucoma; by efficiently

(a) Eyedrops (gutta). This is the simplest and most

controlling intraocular pressure with comparatively

convenient method of topical application, especially

for daytime use. Eyedrops may be in the form of

fewer side-effects.

aqueous solutions (drug totally dissolved) or

(e) Soft contact lenses. These are very good for

aqueous suspensions (drug is present as small

delivering higher concentrations of drugs in

particles kept suspended in the aqueous medium) or

emergency treatment. A pre-soaked soft contact lens

oily solutions. Application in the form of eyedrops

in 1 percent pilocarpine has been found as effective

makes the drug available for immediate action but it

as 4 percent pilocarpine eyedrops in patients with

is quickly diluted by tears within about a minute.

acute angle closure glaucoma. Soft contact lenses

(b) Eye ointment (oculenta or ung). Topical

are also used to deliver antibiotics and antiviral drugs

application in the form of an eye ointment increases

in patients with corneal ulcers.

418

Comprehensive OPHTHALMOLOGY

Intraocular penetration of topically instilled drugs

4. Systemic administration

Topically instilled medications largely penetrate

The systemic routes include oral intake and

intraocularly through the cornea. The main barrier

intramuscular and intravenous injections. The

through cornea is its epithelium, which is lipophilic,

intraocular penetration of systemically administered

and crossed readily by non-polar drugs. Stroma being

drugs mainly depends upon the blood-aqueous

barrier. The passage through blood-aqueous barrier

hydrophilic allows rapid passage of the drug through

endothelium into the anterior chamber. So following

in turn is influenced by the molecular weight and the

lipid solubility of the drug.

features will allow better penetration of drugs through

Only low molecular weight drugs can cross this

the cornea:

blood-aqueous barrier. No passage is allowed to large-

Drugs which are soluble both in water and fats.

sized molecules, such as penicillin. Out of the

Pro-drug forms are lipophilic and after absorption

borderline molecular weight drugs, those with high

through epithelium are converted into proper

lipid solubility can pass easily e.g., sulphonamides

drugs which can easily pass through stroma.

have the same molecular weight as sucrose but are 16

Agents that reduce surface tension increase

times more permeable due to their lipid solubility.

corneal wetting and therefore present more drug

Similarly, chloramphenicol being lipid soluble also

for absorption. Benzalkonium chloride used as

enters the eye easily.

preservative also acts as a wetting agent and

thus increases the drug absorption.

COMMON OCULAR THERAPEUTICS

The agents commonly used in ophthalmology include:

2. Periocular injections

antibacterial, antiviral, antifungal, antiglaucoma,

These are not infrequently employed to deliver drugs.

corticosteroids, nonsteroidal anti-inflammatory drugs

These include subconjunctival, sub-Tenon,

(NSAIDs) and viscoelastic substances.

retrobulbar and peribulbar injections.

(a) Subconjunctival injections. These are commonly

ANTIBACTERIAL AGENTS

used to achieve higher concentration of drugs.

Antimicrobial drugs are the greatest contribution of

Further, the drugs which cannot penetrate the cornea

the present century to therapeutics. As there are a

owing to large-sized molecules can easily pass

wide range of microorganisms, there are also specific

through the sclera.

antibiotics for almost each organism. Depending on

(b) Sub-Tenon injections. These are preferred over

the type of action, these can be either bacteriostatic

subconjunctival injection. Anterior sub-Tenon

or bactericidal. A few common antimicrobials

injections are used mainly to administer steroids in

described here are grouped on the basis of their

the treatment of severe or resistant anterior uveitis.

chemical structure.

Posterior sub-Tenon injections are indicated in

Sulphonamides

patients with intermediate and posterior uveitis.

These are bacteriostatic agents that act by

competing with PABA (para-aminobenzoic acid)

drugs for optic neuritis, papillitis, posterior uveitis

which is essential for the bacterial cell nutrition. Thus,

and also for administering retrobulbar block

they prevent susceptible microorganisms from

anaesthesia.

synthesizing folic acid.

(d) Peribulbar injections. These are now frequently

In ophthalmology, these are used topically and

used for injecting anaesthetic agents. Peribulbar

systemically in the treatment of chlamydial infections,

anaesthesia has almost replaced retrobulbar and facial

viz., trachoma and inclusion conjunctivitis. They are

block anaesthesia.

also helpful as an adjunct to pyrimethamine in the

treatment of toxoplasmosis.

3. Intraocular injections

Such injections are made in desperate cases (e.g.,

Beta-lactam antibiotics

endophthalmitis) to deliver the drugs in maximum

These antibiotics have a beta-lactam ring. The two

concentration at the target tissue. These include:

important groups are penicillins, and cephalosporins.

intracameral injection (into the anterior chamber),

All beta-lactam antibiotics act by interfering with the

and intravitreal injection (into the vitreous cavity).

synthesis of bacterial cell wall.

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

419

A. Penicillins. These are produced by growing one

positive cocci and thus have useful antista-

of the penicillium moulds in deep tanks. These may

phylococcal activity. These include cefazolin,

be categorised as: natural penicillins and

cephradine, cephalexin and cephadroxyl.

semisynthetic penicillins.

2. Second-generation

(intermediate spectrum)

In deep-seated inflammations of the orbit or lids,

cephalosporins. These have antistaphylococcal

penicillin is given parenterally. In superficial

activity and are also effective against certain

inflammations of the conjunctiva and cornea it is

gram-negative organisms. They comprise

administered locally as drops or ointments. In

cefuroxime, cefamandole and cefoxitin.

intraocular infections it is given as subconjunctival

3. Third-generation

(wide spectrum) cephalo-

injections. Commonly used preparations are as

sporins. These are mainly effective against gram-

negative organisms but not against staphylococci.

follows:

These include: cefotaxime, cefixime and cefotetan.

Benzyl penicillin. A dose of 500,000 units twice

daily is sufficient for sensitive infections and

Side-effects. Cephalosporins have a low frequency

produces high levels in all tissues except CNS

of adverse effects in comparison to antimicrobials in

and eye.

general. The most usual are allergic reactions of the

Procaine penicillin. This is an intramuscular

penicillin type. If these are continued for more than 2

depot preparation which provides tissue levels

weeks, thrombocytopenia, neutropenia, interstitial

up to 24 hours.

nephritis or abnormal liver function tests may occur.

Methicillin, cloxacillin and flucloxacillin. These

These resolve on stopping the drug.

penicillins are not affected by penicillinase and

Aminoglycosides

are, therefore, used for staphylococcal infections

These are bactericidal and act primarily against gram-

which are resistant to other penicillins.

negative bacilli. These are not absorbed orally,

Carbenicillin. It is resistant to the penicillinase

distributed mainly extracellularly and are excreted

produced by some strains of Proteus,

unchanged in the urine. These are ototoxic and

Pseudomonas and coliform organisms. It is

nephrotoxic. Certain aminoglycosides are too toxic

ineffective by mouth.

for systemic use and hence used only topically.

Ampicillin. It is a broad-spectrum penicillinase-

Commonly used preparations are as follows:

sensitive penicillin. It is acid resistant and usually

1. Streptomycin. It is used mainly in tuberculosis.

administered orally.

2. Gentamicin. It has become the most commonly

Its dosage is 0.25-2 g oral/i.m./i.v. depending

used aminoglycoside for acute infections. It has

upon the severity of infection every

6 hours.

a broader spectrum of action and is effective

Paediatric dose is 25-50 mg/kg/day.

against Pseudomonas aeruginosa. It is

Amoxycillin. Its spectrum is similar to ampicillin

nephrotoxic, therefore, its dose must be precisely

except that it is less effective against Shigella

calculated according to body weight and renal

and H. influenzae. Its oral absorption is better

function. For an average adult with normal renal

than ampicillin and thus higher and more sustained

function, the dose is 1-1.5 mg/kg intramuscularly

blood levels are produced. Incidence of diarrhoea

8 hourly. Topically, it is used as 0.3% eyedrops.

is less with it than with ampicillin and is thus

3. Tobramycin. It is 2-4 times more active against

better tolerated orally.

Pseudomonas aeruginosa and Proteus as

B. Cephalosporins. These drugs have a similar

compared to gentamicin. Topically, it is used as

structure and mode of action as penicillin. All the

1% eyedrops.

cephalosporins have a bactericidal action against a

4. Amikacin. It is recommended as a reserve drug

wide range of organisms. By convention these have

for hospital acquired gram-negative bacillary

been categorised into three generations of broadly

infections where gentamicin resistance is

similar antibacterial and pharmacokinetic properties:

increasing.

1. First-generation

(narrow spectrum) cephal-

5. Neomycin. It is a widespectrum aminoglycoside,

osporins. These are very active against gram-

active against most gram-negative bacilli and

420

Comprehensive OPHTHALMOLOGY

some gram-positive cocci. However, Pseudomonas

Preparations. Fluroquinolones by convention have

and Streptococcus pyogenes are not sensitive to

been grouped into four generations (Table 18.1).

it. It is highly toxic to internal ear and kidney and

Table 18.1. Commonly used fluoroquinolones

hence used only topically (0.3-0.5%).

6. Framycetin. It is very similar to neomycin. It is

Generation and

Preparation and doses

drug

also too toxic for systemic use and hence used

Topical

Systemic

only topically. It is available as 1 percent skin

First generation

cream; 0.5 percent eye ointment and eyedrops.

Ciprofloxacin

0.3%,

500 mg orally

1 to 4 hrly.

12 hrly.

Tetracyclines

200 mg I/V

These are broad-spectrum bacteriostatic agents with

12 hrly.

Norfloxacin

0.3%,

400 mg orally

a considerable action against both gram-positive and

1 to 4 hrly.

12 hrly.

gram-negative organisms as well as some fungi,

Second generation

rickettsiae and chlamydiae. This group includes

Ofloxacin

0.3%,

200-400 mg

tetracycline, chlortetracycline and oxytetracycline.

1 to 4 hrly.

orally 12 hrly.

200 mg I/V

Chloramphenicol

12 hrly.

Lomefloxacin

0.3%,

400 mg

It is also a broad-spectrum antibiotic, primarily

1 to 4 hrly.

orally OD

bacteriostatic, effective against gram-positive as well

Pefloxacin

0.3%,

400 mg orally or

as gram-negative bacteria, rickettsiae, chlamydiae and

1 to 4 hrly.

I/V 12 hrly.

mycoplasma.

Third generation

Sparfloxacin

0.3%

400 mg orally on

Its molecule is relatively small and lipid soluble.

1 to 4 hrly.

day 1 followed by

Therefore, on systemic administration, it enters the

200 mg OD

eye in therapeutic concentration. Topically it is used

Fourth generation

as 0.5% eyedrops.

Gatifloxacin

0.3%

400 mg OD

1 to 4 hrly.

Polypeptides

Moxifloxacin

0.5%

400 mg OD

1 to 4 hrly.

These are powerful bactericidal agents, but rarely

used systemically due to toxicity. Clinically used

ANTIVIRAL DRUGS

polypeptides are polymyxin B, bacitracin, colistin and

tyrothricin.

These are more often used locally in the eye.

Currently available antiviral agents are virostatic.

1. Polymyxin B and colistin. These are active

They are active against DNA viruses; especially

against most gram-negative bacteria, notably

herpes simplex virus. Antiviral drugs used in

Pseudomonas.

ophthalmology can be grouped as below:

2. Neosporin (neomycin-polymyxin-bacitracin). It is

For herpes simplex virus infection

an effective broad-spectrum antimicrobial but

Idoxuridine

suffers the disadvantage of a high incidence (6-

Vidarabine

8%) of sensitivity due to neomycin.

Trifluridine

Acyclovir

Fluoroquinolones

Famiciclovir

Fluoroquinolones are potent synthetic agents having

For herpes zoster virus infection

broad spectrum of activity against gram-positive and

Acyclovir

gram negative-organisms.

Famiciclovir

Mechanism of action. Fluoroquinolones are

Valaciclovir

bactericidal drugs. These inhibit the bacterial DNA

Vidarabine

synthesis.

Sorvudine

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

421

For CMV retinitis

3. Cytosine-Arabinoside (Cytarabine). It is a purine

Ganciclovir

nucleoside, Mechanism of action: It blocks nucleic

acid synthesis by preventing conversion of cytosine

Foscarnet

ribose to cytosine deoxyribose.

Zidovudin

Preparation: It is not commercially available at

Non selective

present. 5 percent solution used as drops has been

Interferons

found experimentally effective for treatment of herpes

Immunoglobulins

simplex keratitis.

Side-effects. It causes profound corneal epithelial

Some of the antiviral drugs are described in brief.

toxicity with superficial punctate keratitis and iritis.

1. Idoxuridine (IDU, 5-iodo-2 deoxyuridine). It is a

So it is not recommended for clinical use.

halogenated pyrimidine resembling thymidine.

4. Triflurothymidine (TF₃). It is a pyrimidine

Mechanism of action. It inhibits viral metabolism by

nucleoside. It has the advantage over IDU of higher

substituting for thymidine in DNA synthesis and thus

solubility, greater potency, lack of toxicity and allergic

prevents replication of virus.

reactions. It is also effective in IDU-resistant cases.

Topically it is used as 10% eye drops.

Mechanism of action: It is a DNA inhibitor with same

Preparations. It is available as 0.1 percent eye drops

mechanism as IDU. Preparation: It is available as 1

per cent eyedrops.

and 0.5 percent eye ointment.

Dose: One drop is instilled 4 hourly. If no improvement

Indications and doses: Since the intraocular

occurs in 14 days, it is better to change to some other

penetration of topically applied IDU is very poor, it is

antiviral drug.

not of much value in the treatment of chronic stromal

Toxicity: It is least toxic. It may cause mild superficial

herpetic keratitis. It is mainly used in acute epithelial

punctate keratitis on prolonged use.

herpetic keratitis. IDU drops are used one hourly

5. Acyclovir (Acycloguanosine). It has proved to be

during day and two hourly during night and has to

an extremely safe and effective agent and is effective

be continued till microscopic staining disappears.

in most forms of herpes simplex and herpes zoster

Side-effects include follicular conjunctivitis, lacrimal

infections.

punctal stenosis and irritation with photophobia.

Mechanism of action: It inhibits viral DNA,

Contraindications. It is known to inhibit corneal

preferentially entering the infected cells, with little

effect on normal cells. It penetrates into deeper layers

stromal healing, hence its use is not advisable during

and thus is very effective in stromal keratitis.

first few weeks after keratoplasty.

Preparation. It is available as 3 percent ophthalmic

2. Adenine arobinoside (Ara-A, Vidarabine). It is a

ointment and also as tablet for oral use and injection

purine nucleoside. It has antiviral activity against

for intravenous use.

herpes simplex, cytomegalo, vaccinia and zoster

Indications and doses: (a) Topical 3 percent ointment

viruses. It is more potent and less toxic than IDU and

is used 5 times a day for epithelial as well as stromal

is also effective in IDU resistant cases. It has no cross

herpes simplex keratitis (b) Oral acyclovir four tablets

allergenicity with IDU or TF₃ and thus can be used

of 200 mg each, 5 times a day for 5-7 days, may be

with IDU.

considered in following situations: (i) After

Mechanism of action: It is metabolized to

penetrating keratoplasty in patients suffering from

triphosphate form which inhibits DNA polymerase

herpes simplex keratitis. (ii) Recalcitrant stromal or

uveal disease caused by HSV. (iii) To reduce ocular

and thus the growth of viral DNA is arrested.

complications of keratitis and uveitis in herpes zoster

Preparations: It is available as 3% ophthalmic

ophthalmicus. Side-effects: A few cases show slight

ointment.

punctate epithelial keratopathy which ceases once

Dose: It is used 5 times a day till epithelization occurs

the drug is stopped.

and then reduced to once or twice daily for 4-5 days

6. Valaciclovir. It is used for treatment of herpes

to prevent recurrences. Side-effects are superificial

zoster ophthalmicus in a dose of 500-700 mg TDS for

punctate keratitis and irritation on prolonged

7 days. It is as effective as acyclovir in acute disease

application.

and is more effective in reducing late neuralgia.

422

Comprehensive OPHTHALMOLOGY

7. Famiciclovir. Its use, dose and effectivity is similar

2. Amphotericin B (Fungizone). This antibiotic may

to valaciclovir.

act as fungistatic or fungicidal depending upon

8. Interferons. These are non-toxic, species-specific

the concentration of the drug and sensitivity of

proteins possessing broad-spectrum antiviral activity.

the fungus. Topically, it is effective in superficial

However, it is still not available for commercial use.

infections of the eye in the concentration of 0.075

9. Immunoglobulins. These preparations may be

to 0.3 percent drops. Subconjunctival injections

useful in the treatment or prophylaxis of certain viral

are quite painful and more than 300 mg is poorly

diseases especially in patients with immune

tolerated.

Amphotericin B may be given intravitreally or/

deficiencies.

and intravenously for treatment of intraocular

10. Ganciclovir. It is used for the treatment of CMV

infections caused by Candida, Histoplasma,

retinitis in immunocompromised individuals. Dose: 5

Cryptococcus and some strains of Aspergillus

mg/kg body weight every 12 hours for 2-3 weeks,

and others. For intravenous administration a

followed by a permanent maintenance dose of 5 mg/

solution of 0.1 mg/ml in 5 percent dextrose with

kg once daily for 5 out of 7 days.

heparin is used.

11. Foscarnet (Phosphonoformic acid; PFA). It is

3. Natamycin (Pimaricin). It is a broad-spectrum

as effective as ganciclovir in the treatment of CMV

antifungal drug having activity against Candida,

retinitis in AIDS patients.

Aspergillus, Fusarium and Cephalosporium.

12. Zidovudin (azidothymidine; AZT). It has been

Topical application of

5 percent pimaricin

recently recommended for selected AIDS patients with

suspension produces effective concentrations

non-vision threatening retinitis who have no evidence

within the corneal stroma but not in intraocular

of systemic CMV infection.

fluid. It is the drug of choice for fusarium solani

keratitis. It adheres well to the surface of the

OCULAR ANTIFUNGAL AGENTS

ulcer, making the contact time of the antifungal

A number of antifungal agents have become available

agent with the eye greater. It is not recommended

in the recent years. These can be broadly classified

for injection.

on the basis of their chemical structure into polyene

II. Imidazole antifungal drugs

antibiotics, imidazole derivatives, pyrimidines and

Various imidazole derivatives available for use in

silver compounds.

ocular fungal infections include: miconazole,

I. Polyene antifungals

clotrimazole, ketoconazole, econazole and

These have been the mainstay of antifungal therapy.

itraconazole.

These are isolated from various species of

1. Miconazole. It possesses a broad antifungal

spectrum and is fungicidal to various species of

Streptomyces and consist of a large, conjugated,

Candida, Aspergillus, Fusarium, Cryptococcus,

double-bond system in a lactose ring linked to an

Cladosporium, Trichophyton and many others.

amino acid sugar.

Topical

(1%) and subconjunctival

(10 mg)

Mechanism of action. They work by binding to the

application of miconazole produces high levels of

sterol groups in fungal cell membranes, rendering

the drug in the cornea which is more dramatic in

them permeable. This occurrence leads to lethal

the presence of epithelial defect.

imbalances in cell contents. Polyenes do not penetrate

2. Clotrimazole. It is fungistatic and is effective

well into the cornea and are not beneficial in deep

against Candida, Aspergillus and many others.

stromal keratitis.

Its

1 percent suspension is effective topically

Preparations. This group includes following drugs:

and is the treatment of choice in Aspergillus

1. Nystatin. It is fungistatic and is well tolerated in

infections of the eye.

the eye as 3.5 percent ointment. It has a medium

3. Econazole. It also has broad-spectrum antifungal

level of activity in ocular infections caused by

activity and is used topically as

1 percent

Candida or Aspergillus isolates. Because of its

econazole nitrate ointment. Becaue of its poor

narrow spectrum and poor intraocular penetration

intraocular penetration, it is effective only in

its use is restricted.

superficial infections of the eye.

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

423

4. Ketoconazole. It is effective after oral

A. Parasympathomimetic drugs (Miotics)

administration and possesses activity against

Parasympathomimetics, also called as cholinergic

common fungi. It is given as single oral dose of

drugs, either imitate or potentiate the effects of

200-400 mg daily up to at least one week after the

acetylcholine.

symptoms have disappeared. It is an adjunctive

Classification

systemic antifungal agent in fungal keratitis

complicated by endophthalmitis.

Depending upon the mode of action, these can be

5. Fluconazole. It is fungistatic drug active against

classified as follows:

Candida, Aspergillus and Cryptococcus. It is

1. Direct-acting or agonists e.g., pilocarpine.

available for oral use (50-100 mg tablets) and also

2. Indirect-acting parasympathomimetics or

for topical use (0.2% eyedrops).

cholinesterase inhibitors: As the name indicates

6. Itraconazole. It is prescribed for treatment of

these drugs act indirectly by destroying the

fungal infections caused primarily by Aspergillus,

enzyme cholinesterase; thereby sparing the

Histoplasmosis, Blastomycosis. It has moderate

naturallyacting acetylcholine for its actions. These

effect against Candida and Fusarium infections.

drugs have been divided into two subgroups,

It is available for oral and topical use. Oral dose

designated as reversible

(e.g., physostigmine)

is 200 mg twice daily for a week. Topically it is

and irreversible

(e.g., echothiophate iodide,

used as 1% eye drops.

demecarium and diisopropyl-fluoro-phosphate,

DFP₃) antic-holinesterases.

III. Pyridine

3. Dual-action parasympathomimetics, i.e., which

This group includes flucystosine, which is a

act as both a muscarinic agonist as well as a

fluorinated salt of pyrimidine. Its mechanism of action

weak cholinesterase inhibitor e.g., carbachol.

is not clear. The drug is very effective against Candida

Mechanism of action

species and yeasts. It is used as 1.5 percent aqueous

1. In primary open-angle glaucoma the miotics

drops hourly. It can also be given orally or

reduce the intraocular pressure

(IOP) by

intravenously in doses of 200 mg/kg/day.

enhancing the aqueous outflow facility. This is

IV. Silver compounds

achieved by changes in the trabecular meshwork

Combination of silver with sulfonamides and with

produced by a pull exerted on the scleral spur by

other anti-microbial compounds significantly

contraction of the longitudinal fibres of ciliary

increases the activity against bacterial and fungal

muscle.

infections. In this context several silver compounds

2. In primary angle-closure glaucoma these reduce

have been synthesized. Most frequently used is silver

the IOP due to their miotic effect by opening the

sulphadiazine which is reported to be highly effective

angle. The mechanical contraction of the pupil

against Aspergillus and Fusarium species.

moves the iris away from the trabecular meshwork.

Side-effects

MYDRIATICS AND CYCLOPLEGICS

1. Systemic side-effects noted are: bradycardia,

(See pages 98, 146 and 550)

increased sweating, diarrhoea, excessive salivation

and anxiety. The only serious complication noted

ANTI-GLAUCOMA DRUGS

with irreversible cholinesterase inhibitors is

Classification

‘scoline apnoea’, i.e., inability of the patient to

A.Parasympathomimetic drugs (Miotics)

resume normal respiration after termination of

B. Sympathomimetic drugs (Adrenergic agonists)

general anaesthesia.

C. β-blockers

2. Local side-effects are encountered more frequently

D. Carbonic anhydrase inhibitors

with long-acting miotics

(i.e. irreversible

E. Hyperosmotic agents

cholinesterase inhibitors). These include problems

F. Prostaglandins

due to miosis itself (e.g. reduced visual acuity in

G. Calcium channel blockers

the presence of polar cataracts, impairment of

424

Comprehensive OPHTHALMOLOGY

night vision and generalized contraction of visual

B. Sympathomimetic drugs

fields), spasm of accommodation which may cause

Sympathomimetics, also known as adrenergic

myopia and frontal headache, retinal detachment,

agonists, act by stimulation of alpha, beta or both

lenticular opacities, iris cyst formation, mild iritis,

the receptors.

lacrimation and follicular conjunctivitis.

Classification

Preparations

Depending upon the mode of action, these can be

1. Pilocarpine. It is a direct-acting parasym-

classified as follows:

pathomimetic drug. It is the most commonly used and

1. Both alpha and beta-receptor stimulators e.g.,

the most extensively studied miotic. Indications: (i)

epinephrine.

Primary open-angle glaucoma; (ii) Acute angle-closure

2. Direct alpha-adrenergic stimulators e.g.,

glaucoma; (iii) Chronic synechial angle-closure

norepinephrine and clonidine hydrochloride.

glaucoma. Contraindications: inflammatory

3. Indirect alpha-adrenergic stimulators e.g.,

glaucoma, malignant glaucoma and known allergy.

pargyline.

Available preparations and dosage are: (a) Eyedrops

4. Beta-adrenergic stimulator e.g., isoproterenol.

are available in 1%, 2% and 4% strengths. Except in

very darkly pigmented irides maximum effect is

Mechanisms of action

obtained with a 4 percent solution. In POAG, therapy

1. Increased aqueous outflow results by virtue of

is usually initiated with 1 percent concentration. The

both alpha and beta-receptor stimulation.

onset of action occurs in 20 minutes, peak in 2 hours

2. Decreased aqueous humour production occurs

and duration of effect is 4-6 hours. Therefore, the

due to stimulation of alpha-receptors in the ciliary

eyedrops are usually prescribed every 6 or 8 hourly.

body.

(b) Ocuserts are available as pilo-20 and pilo-40. These

Side-effects

are changed once in a week. Pilo-20 is generally used

in patients controlled with 2 percent or less

1. Systemic side-effects include hypertension,

concentration of eyedrops; and pilo-40 in those

tachycardia, headache, palpitation, tremors,

requiring higher concentration of eyedrops.

nervousness and anxiety.

2. Local side-effects are burning sensation, reactive

daytime medication.

hyperaemia of conjunctiva, conjunctival

2. Carbachol. It is a dual-action (agonist as well as

pigmentation, allergic blepharo conjunctivitis,

weak cholinesterase inhibitor) miotic. Indications. It

mydriasis and cystoid macular oedema

(in

is a very good alternative to pilocarpine in resistant

aphakics).

or intolerant cases. Preparations. It is available as

Preparations

0.75 percent and 3 percent eyedrops. Dosage: The

1. Epinephrine. This direct-acting sympathomimetic

action ensues in 40 minutes and lasts for about 12

hours. Therefore, the drops are instilled 2 or 3 times a

drug stimulates both alpha and beta- adrenergic

day.

receptors. Indications: (i) It is one of the standard

3. Echothiophate iodide (Phospholine iodide). It is

drugs used for the management of POAG. (ii) It is also

a long acting cholinesterase inhibitor. Indications: It

useful in most of the secondary glaucomas.

is very effective in POAG. Preparations: Available

Preparations: It is available as 0.5 percent, 1 percent

as 0.03, 0.06 and 0.125 percent eye- drops. Dosage:

and 2 percent eyedrops. Dosage: The action starts

The onset of action occurs within 2 hours and lasts

within 1 hour and lasts up to 12-24 hours. Therefore,

up to 24 hours. Therefore, it is instilled once or twice

it is instilled twice daily.

daily.

2. Dipivefrine (Propine or dipivalylepinephrine). It is a

4. Demecarium bromide. It is similar to ecothiopate

prodrug which is converted into epinephrine after its

iodide and is used as 0.125 percent or 0.25 per- cent

absorption into the eye. It is more lipophilic than

eyedrops.

epinephrine and thus its corneal penetration is

5. Physostigmine (eserine). It is a reversible (weak)

increased by 17 times. Preparations: It is available as

cholinesterase inhibitor. It is used as 0.5 percent

0.1 percent eyedrops. Dosage: Action and efficacy is

ointment twice a day.

similar to 1 percent epinephrine. It is instilled twice daily.

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

425

3. Clonidine hydrochloride. It is a centrally-acting

failure or cardiomyopathy. Betaxolol is the beta

systemic antihypertensive agent, which has been

blocker, of choice in patients at risk for pulmonary

shown to lower the IOP by decreasing aqueous

diseases. The other contraindication includes known

humour production by stimulation of alpha-receptors

drug allergies.

in the ciliary body. Preparations and dosage. It is

Additive effects. Beta-blockers have very good

used as 0.125 percent and 0.25 percent eye drops,

synergistic effect when combined with miotics; and

twice daily.

are thus often used in combination in patients with

4. Brimonidine (0.2%). Mechanism of action. It is a

POAG, unresponsive to the single drug.

selective alpha-2 adrenergic agonist and lowers IOP

Side-effects

by decreasing aqueous production and enhancing

1. Ocular side-effects are not frequent. These include

uveoscleral outflow. It has an additive effect to beta-

burning and conjunctival hyperaemia, superficial

blockers. Dosage: It has a peak effect of 2 hours and

punctate keratopathy and corneal anaesthesia.

action lasts for 12 hours; so it is administered twice

2. Systemic side-effects are also unusually low.

daily.

However, these are reported more often than ocular

5. Apraclonidine (0.5%, 1%). It is also alpha-2

side-effects. These include (i) Cardiovascular effects

adrenergic agonist like brimonidine. It is an extremely

which result from blockade of beta-1 receptors. These

potent ocular hypotensive drug and is commonly used

are bradycardia, arrhythmias, heart failure and

prophylactically for prevention of IOP elevation

syncope. (ii) Respiratory reactions: These include

following laser trabeculoplasty, YAG laser iridotomy

bronchospasm and airway obstruction, especially in

and posterior capsulotomy. It is of limited use for

asthmatics. These occur due to blockade of beta-2

long-term administration because of the high rate of

receptors; and thus are not known with betaxolol.

ocular side-effects.

(iii) Central nervous system effects. These include

C. Beta-adrenergic blockers

depression, anxiety, confusion, drowsiness,

disorientation, hallucinations, emotional lability,

These are, presently, the most frequently used

dysarthria and so on. (iv) Miscellaneous effects are

antiglaucoma drugs. The commonly used

nausea, diarrhoea, decreased libido, skin rashes,

preparations are timolol and betaxolol. Other available

alopecia and exacerbation of myasthenia gravis.

preparations include levobunolol, carteolol and

metipranolol.

Preparations

Mechanism of action. Timolol and levobunolol are

1. Timolol. It is a non-selective beta-1 and beta-2

non-selective beta-1 (Cardiac) and beta-2 (smooth

blocker. It is available as 0.25 per cent and 0.5 percent

muscle, pulmonary) receptor blocking agents.

eye drops. The salt used is timolol maleate. Its action

Betaxolol has 10 times more affinity for beta-1 than

starts within 30 minutes, peak reaches in 2 hours and

beta-2 receptors.

effects last up to 24 hours. Therefore, it is used once

The drugs timolol and levobunolol lower IOP by

or twice daily. The drug is very effective, however,

blockade of beta-2 receptors in the ciliary processes,

the phenomenon of ‘short-term escape’ and ‘long-

resulting in decreased aqueous production. The exact

term drift’ are well known. ‘Short-term escape’ implies

mechanism of action of betaxolol (cardioselective

marked initial fall in IOP, followed by a transient rise

beta-blocker) is unknown.

with continued moderate fall in IOP. The ‘long-term

Indications. Beta adrenergic blockers are useful in

drift’ implies a slow rise in IOP in patients who were

all types of glaucomas, viz., developmental, primary

well controlled with many months of therapy.

and secondary; narrow as well as open angle. Unless

2. Betaxolol. It is a cardioselective beta-blocker and

contraindicated due to systemic diseases, beta-

thus can be used safely in patients prone to attack of

blockers are frequently used as the first choice drug

bronchial asthma; an advantage over timolol. It is

in POAG and all secondary glaucomas.

available as 0.5 percent suspension, and 0.25 percent

Contraindications. These drugs should be used with

suspension, and is used twice daily. Its action starts

caution or not at all, depending on the severity of the

within 30 minutes, reaches peak in 2 hours and lasts

systemic disease in patients with bronchial asthma,

for 12 hours. It is slightly less effective than timolol

emphysema, COPD, heart blocks, congestive heart

in lowering the IOP.

426

Comprehensive OPHTHALMOLOGY

3. Levobunolol. It is available as 0.5 percent solution

4. Gastrointestinal symptom complex. It is also very

and its salient features are almost similar to timolol.

common. It is not related to the malaise symptom

4. Carteolol. It is available as 1 percent and 2 per

complex caused by biochemical changes in the serum.

cent solution and is almost similar to timolol except

Its features include—vague abdominal discomfort,

that it induces comparatively less bradycardia.

gastric irritation, nausea, peculiar metallic taste and

5. Metipranolol. It is available as 0.1 percent, 0.3

diarrhoea.

percent and 0.6 percent solution and is almost similar

5. Sulfonamide related side-effects of CAIs, seen

to timolol in all aspects.

rarely, include renal calculi, blood dyscrasias,

Stevens-Johnson syndrome, transient myopia,

(D) Carbonic anhydrase inhibitors (CAIs)

hypertensive nephropathy and teratogenic effects.

These are potent and most commonly used systemic

antiglaucoma drugs. These include acetazolamide

Preparations and doses

(most frequently used), methazolamide,

1. Acetazolamide (diamox). It is available as tablets,

dichlorphenamide and ethoxzolamide.

capsules and injection for intravenous use. The

Mechanism of action. As the name indicates CAIs

acetazolamide 250 mg tablet is used 6 hourly. Its action

inhibit the enzyme carbonic anhydrase which is

starts within 1 hour, peak is reached in 4 hours and

related to the process of aqueous humour production.

the effect lasts for 6-8 hours.

Thus, CAIs lower the IOP by reducing the aqueous

2. Dichlorphenamide. It is available as 50 mg tablets.

humour formation.

Its recommended dose is 25 to 100 mg three times a

Indications. These are used as additive therapy for

day. It causes less metabolic acidosis but has a

short term in the management of all types of acute

sustained diuretic effect.

and chronic glaucomas. Their long-term use is

3. Methazolamide. It is also available as 50 mg tablets.

reserved for patients with high risk of visual loss,

It has a longer duration of action than acetazolamide.

where all other treatments fail.

Its dose is 50-100 mg, 2 or 3 times a day.

Side-effects. Unfortunately, 40-50 percent of patients

4. Ethoxzolamide. It is given in a dosage of 125 mg

are unable to tolerate CAIs for long term because of

every 6 hours and is similar to acetazolamide in all

various disabling side-effects. These include:

aspects.

1. Paresthesias of the fingers, toes, hands, feet and

5. Dorzolamide (2%). It is a topical carbonic

around the mouth are experienced by most of the

anhydrase inhibitor. It is water soluble, stable in

patients. However, these are transient and of no

solution and has excellent corneal penetration. It

consequence.

decreases IOP by 22% and has got additive effect

2. Urinary frequency may also be complained of by

with timolol. It is administered thrice daily. Its side

most patients due to the diuretic effect.

effects include burning sensation and local allergic

3. Serum electrolyte imbalances may occur with

reaction.

higher doses of CAIs. These may be in the form of (i)

6. Brinzolamide (1%). It is also a topical CAI which

Bicarbonate depletion leading to metabolic acidosis.

This is associated with ‘malaise symptom complex’,

decreases IOP by decreasing aqueous production. It

which includes: malaise, fatigue, depression, loss of

is administered twice daily (BD).

libido, anorexia and weight loss. Treatment with

E. Hyperosmotic agents

sodium bicarbonate or sodium acetate may help to

These are the second class of compounds, which are

minimize this situation in many patients. (ii) Potassium

administered systemically to lower the IOP. These

depletion. It may occur in some patients, especially

include: glycerol, mannitol, isosorbide and urea.

those simultaneously getting corticosteroids, aspirin

or thiazide diuretics. Potassium supplement is

Mechanism of action. Hyperosmotic agents increase

indicated only when significant hypokalemia is

the plasma tonicity. Thus, the osmotic pressure

documented. (iii) Serum sodium and chloride may be

gradient created between the blood and vitreous

transiently reduced; more commonly with

draws sufficient water out of the eyeball, thereby

dichlorphenamide.

significantly lowering the IOP.

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

427

Indications. These are used as additive therapy for

3. Travoprost

(0.004%). It is a synthetic

rapidly lowering the IOP in emergency situations,

prostaglandin F₂ analogue and decreases IOP by

such as acute angle-closure glaucoma or secondary

increasing uveoscleral outflow of aqueous.

glaucomas with very high IOP. They are also used as

4. Unoprostive isopropyl (0.12%). It is a dolosanoid

a prophylactic measure prior to intraocular surgery.

related in structure to prostaglandin F₂-α. It lowers

IOP by increasing uveoscleral outflow of aqueous. It

Preparations and doses

also increases retinal blood flow.

1. Glycerol. It is a frequently used oral hyperosmotic

agent. Its recommended dose is 1-1.5 gm/kg body

G. Calcium channel blockers

weight. It is used as a 50 percent solution. So, glycerol

Calcium channel blockers such as nifedipine, diltiazem

(50 to 80 ml in adults) is mixed with equal amount of

and verapamil are commonly used antihypertensive

lemon juice (preferably) or water before administering

drugs. Recently, some of these have been used as

orally. Its action starts in 10 minutes, peaks in 30

anti-glaucoma drugs.

minutes and lasts for about 5-6 hours. It can be given

Mechanism of action. The exact mechanism of

repeatedly. It is metabolised to glucose in the body.

lowering IOP of topically used calcium channel

Thus, its repeated use in diabetics is not

blockers remains to be elucidated. It might be due to

recommended.

its effects on secretory ciliary epithelium.

2. Mannitol. It is the most widely used intravenous

Preparations. Verapamil has been tried as 0.125

hyperosmotic agent. It is indicated when the oral

percent and 0.25 percent eyedrops twice a day.

agents are felt to be insufficient or when they cannot

Indications. Though the IOP lowering effect of

be taken for reasons such as nausea. Its recommended

verapamil is not superior than the standard topical

dose is 1-2 gm/kg body weight. It is used as a 20

antiglaucoma drugs, it has a place in the mangement

percent solution. It should be administered very

of patients with POAG, where miotics, beta-blockers

rapidly over 20-30 minutes. Its action peaks in 30

and sympathomimetics are all contraindicated e.g., in

minutes and lasts for about 6 hours. It does not enter

patients suffering simultaneously from axial cataract,

the glucose metabolism and thus is safe in diabetics.

bronchial asthma and raised blood pressure. It can

However, it should be used cautiously in hypertensive

also be used for additive effect with pilocarpine and

patients.

timolol.

3. Urea. When administered intravenously it also

lowers the IOP. However, because of lower efficacy

Antiglaucoma drugs: Mechanism of lowering IOP

at a glance

and more side-effects than mannitol, it is not

recommended for routine use.

Drugs which increase trabecular outflow

4. Isosorbide. It is an oral hyperosmotic agent, similar

Miotics (e.g., pilocarpine)

to glycerol in action and doses. However,

Epinephrine, Dipivefrine

metabolically it is inert and thus can be used

Bimatoprost

repeatedly in diabetics.

Drugs which increase uveoscleral outflow

F. Prostaglandin derivatives

Prostaglandins

(latanoprost)

1. Latanoprost (0.005%). It is a synthetic drug

Epinephrine, Dipivefrine

which is an ester analogue of prostaglandin F₂-α. It

Brimonidine

is acts by increasing uveoscleral outflow and by

Apraclonidine

causing reduction in episcleral venous pressure. It is

Drugs which decrease aqueous production

as effective as timolol. It has additive effect with

pilocarpine and timolol. Its duration of action is 24

Carbonic anhydrase inhibitors (e.g., acetazola-

hours and is, thus, administered once daily. Its side-

mide, dorzolamide)

effects include conjunctival hyperaemia, foreign body

Alpha receptor stimulators in ciliary process

sensation and increased pigmentation of the iris.

(e.g., epinephrine, dipivefrine, clonidine, brimoni-

2. Bimatoprost (0.03%). It is a prostamide which

dine, apraclonidine.

decreases IOP by decreasing ocular outflow

Beta blockers (e.g., timolol, betaxolol, levobunolol)

resistance. It is used once a day (OD).

Hyperosmotic agents (e.g., glycerol, mannitol, urea)

428

Comprehensive OPHTHALMOLOGY

CORTICOSTEROIDS

Betamethasone

0.1% solution and

These are 21-C compounds secreted by the adrenal

sodium phosphate

0.1%

cortex. They have potent anti-inflammatory, anti-

ointment

allergic and anti-fibrotic actions. Corticosteroids

Medryson

1% suspension

reduce inflammation by reduction of leukocytic and

Fluromethalone

0.1% suspension

plasma exudation, maintenance of cellular membrane

Loteprednol

0.5% suspension

integrity with inhibition of tissue swelling, inhibition

(B) Systemic corticosteroid preparations used

of lysosome release from granulocytes, increased

commonly are:

stabilisation of intracellular lysosomal membranes and

Prednisolone

As 5 mg, 10 mg tab and

suppression of circulating lymphocytes.

solution for injection in the

Classification and relative anti-inflammatory drug

strength of 20 mg/ml

potency

Dexamethasone

As 0.5 mg tab and solution

for injection in the strength

See Table 18.2

of 4 mg/ml

Table 18.2: Corticosteroids: equivalent antiinflammatory

Betamethasone

0.5 mg and 1 mg tab

oral dose (mg) and relative antiinflammatory potency.

Drug

Equivalent

Relative anti-

Ocular indications

anti-inflam-

inflammatory

1. Topical preparations are used in uveitis, scleritis,

matory oral

potency

allergic conjunctivitis

(vernal catarrh and

dose (mg)

phlyctenular conjunctivitis), allergic keratitis,

Glucocorticoids

cystoid macular oedema and after intraocular

1. Short acting

surgery.

Hydrocortisone

2. Systemic preparations are indicated in posterior

(Cortisol)

uveitis, sympathetic ophthalmia, Vogt-Koyanagi-

Cortisone

0.8

Harada syndrome (VKH), papillitis, retrobulbar

Prednisolone

Prednisone

neuritis, anterior ischaemic optic neuropathy,

Methylprednisolone

scleritis, malignant exophthalmos, orbital

2. Intermediate-acting

pseudotumours, orbital lymphangioma and corneal

Triamcinolone

graft rejections.

Fluprednisolone

1.5

3. Long-acting

Side-effects

Dexamethasone

0.75

Injudicious use of topical steroids may cause

Betamethasone

0.60

glaucoma, cataract, activation of infection (if given

II. Mineralocorticoids

in herpetic, fungal and bacterial keratitis), dry eye

Fludrocortisone

and ptosis.

Misuse of systemic corticosteroids may cause

Preparations and modes of administration

ocular and systemic side-effects. Ocular complications

Corticosteroids may be administered locally in the

include cataract, glaucoma, activation of infection,

form of drops, ointments or injections and

delayed wound healing, papilloedema, and central

systemically in the form of tablets or injections.

retinal vein occlusion.

(A) Topical ophthalmic preparations used com-

Systemic complications include peptic ulcer,

monly are as follows:

hypertension, osteoporosis, aggravation of diabetes

Cortisone acetate

As 0.5% suspension and 1.5%

mellitus, mental changes, cushingoid state and

ointment

reactivation of tuberculosis and other infections.

Hydrocortisone

As 0.5% suspension acetate

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS

and 0.2% solution

Dexamethasone

As 0.1% solution and sodium

Nonsteroidal anti-inflammatory drugs (NSAIDs),

phosphate 0.5% ointment

often referred to as ‘aspirin-like drugs’, are a

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

429

heterogeneous group of anti-inflammatory, analgesic

Uveitis. NSAIDs are usually not used as the

and antipyretic compounds. These are often

primary agents in therapy of uveitis. They are,

chemically unrelated (although most of them are

however, useful in the long-term therapy of

organic acids), but share certain therapeutic actions

recurrent anterior uveitis, initially controlled by

and side-effects.

steroid therapy. Phenylbutazone is of use in

uveitis associated with ankylosing spondylitis.

Mechanisms of action

Cystoid macular oedema (CME). Topical and/or

The NSAIDs largely act by irreversibly blocking the

systemic antiprostaglandin drugs are effective in

enzyme cyclo-oxygenase, thus inhibiting the

preventing the postoperative CME occurring after

cataract operation. The drug

(e.g.,

0.03%

prostaglandin biosynthesis. They also appear to block

flurbiprofen eyedrops) is started

2 days

other local mediators of the inflammatory response

preoperatively and continued for 6-8 weeks post-

such as polypeptides of the kinin system, lysosomal

operatively.

enzymes, lymphokinase and thromboxane A2; but not

Pre-operatively to maintain dilatation of the

the leukotrienes.

pupil. Flurbiprofen drops used every 5 minutes

for 2 hours preoperatively are very effective in

Preparations

maintaining the pupillary dilatation during the

A. NSAIDs available for systemic use can be

operation of extracapsular cataract extraction with

grouped as follows:

or without intraocular lens implantation.

1. Salicylates e.g., aspirin.

Spring catarrh. Sodium cromoglycate 2 percent

2. Pyrazolone derivatives e.g., phenylbutazone,

inhibits degranulation of the mast cells and thus

oxyphenbutazone, aminopyrine and apazone.

is more useful when used prophylactically in

patients with spring catarrh. Topical

3. Para-aminophenol derivatives e.g., phena-

antiprostaglandins are effective in the treatment

cetin and acetaminophen.

of spring catarrh.

4. Indole derivatives e.g., indomethacin and

Topical antihistaminics are helpful in cases of

sulindac.

mild allergic conjunctivitis.

5. Propionic acid derivatives e.g., ibuprofen,

VISCOELASTIC SUBSTANCES

naproxen and flurbiprofen.

Use of viscous or viscoelastic substances has become

6. Anthranilic acid derivatives e.g., mefenamic

almost mandatory in the modern microphthalmic

acid and flufenamic acid.

surgery, especially intraocular lens implantation,

7. Other newer NSAIDs e.g., ketorolac trometha-

which involves a risk of involuntary tissue damage

mine, carprofen and diclofenac.

due to intraocular manipulations.

B. Topical ophthalmic NSAIDs preparations

Properties of viscoelastic substances

available include:

An ideal viscoelastic substance should have the

1. Indomethacin suspension (0.1%)

following properties:

2. Flurbiprofen, 0.3% eyedrops

1. Chemically the material should be inert, iso-

3. Ketorolac tromethamine, 0.5% eyedrops

osmotic, free from particulate matter, non-

pyrogenic, non-antigenic, non-toxic and sterile.

4. Diclofenac sodium, 0.1% eyedrops

2. Optically clear.

3. Viscosity of the substances should be enough to

Ophthalmic indications of NSAIDs

provide sufficient space for manipulation within

1. Episcleritis and scleritis. Recalcitrant cases of

the eye.

episcleritis may be treated with systemic NSAIDs

4. Hydrophilic and dilutable properties are necessary

such as oxyphenbutazone

100 mg TDS or

to irrigate the material out of the eye after the

indomethacin 25 mg BD.

operation.

NSAIDs may also suppress the inflammation in

5. Protectability and maintenance of space. It

diffuse and nodular varieties of scleritis, but are

should protect the endothelium, separate the

not likely to control the necrotizing form.

tissues, maintain the space and act as a lubricant.

430

Comprehensive OPHTHALMOLOGY

Preparations

LASERS IN OPHTHALMOLOGY

1. Methylcellulose. It is the most commonly used

substance. It is only a viscous and not a

The word LASER is an acronym for ‘Light

viscoelastic substance. Its active ingredient is

Amplification by Stimulated Emission of Radiation’.

highly purified 2% hydroxypropyl methylcellulose.

Laser light is characterised by monochromaticity,

2. Sodium hyaluronate (1%) (Healon). Being

coherence and collimation. These properties make it

extremely viscoelastic and non-inflammatory, it is

the brightest existing light.

the best available viscoelastic substance. However,

PRODUCTION OF LASER BEAM

being expensive, it is less popular than

In the laser system atomic environments of various

methylcellulose.

types are stimulated to produce laser light. A laser

3. Hypromellose (2%). It is a viscous substance

system consists of a transparent crystal rod or a gas

similar to methylcellulose.

or liquid filled cavity constructed with a fully

4. Chondroitin sulfate

(20% and 50%). It is a

reflective mirror at one end and a partially reflective

viscoelastic substance similar to sodium

mirror at the other. Surrounding the rod or cavity is

hyaluronate. It is also available as 1:3 mixture of

an optical or electrical source of energy that will raise

4% chondroitin sulfate and

3% sodium

the energy level of the atoms within the cavity or rod

hyaluronate (Viscoat) and in combination with

to a high and unstable level. This phenomenon is

methylcellulose (Ocugel).

called population inversion. From this level, the atoms

spontaneously decay back to a lower energy level,

Alternatives to viscoelastic substances

releasing the excess energy in the form of light which

Substances used as alternative to viscoelastics for

is amplified to an appropriate wavelength. Thus, laser

maintenance of anterior chamber are air, serum and

is created mainly by two means: population inversion

other blood products and balanced salt solution.

in active medium and amplification of appropriate

However, none of these match the properties of

wavelength of light.

viscoelastic substances.

TYPES OF LASERS

Clinical uses

There are various types of lasers depending upon

the type of atomic environment stimulated to produce

1. Cataract surgery with or without IOL implanta-

the laser beam. Common types of lasers are depicted

tion. It is the most important indication. Here the

in Table 18.3.

viscoelastic substance is used for:

Maintenance of anterior chamber;

Table 18.3. Lasers used in ophthalmology

ii.

Protection of corneal endothelium;

Type of laser

Atomic environ-

Effects

iii. Coating the IOL

ment used

produced

iv. Preventing the entry of blood and fluid in the

1. Argon

Argon gas

Photocoagulation

anterior chamber.

2. Other uses. Viscoelastic substances are also

2. Krypton

Krypton gas

Photocoagulation

useful in glaucoma surgery, keratoplasty, retinal

3. Diode

Diode crystal

Photocoagulation

detachment surgery and repair of the globe in

4. Diode-

Diode and

Photocoagulation

pumped

Nd:YAG

perforating injuries.

frequency crystals

doubled

Side-effects

Nd:YAG

Post-operative rise in intraocular pressure may occur

5. Nd:YAG

A liquid dry or a

Photodisruption

if a considerable amount of viscoelastic substance is

solid compound

left inside the anterior chamber; so it must be washed

of yttrium-alumi-

off after surgery.

nium garnet and

neodymium

VITREOUS SUBSTITUTES

6. Excimer

Helium and

Photoablation

flourine gas

See page 247.

OCULAR THERAPEUTICS, LASERS AND CRYOTHERAPY IN OPHTHALMOLOGY

431

MECHANISMS OF LASER EFFECTS AND THEIR

Macular diseases, such as central serous

THERAPEUTIC APPLICATIONS

retinopathy, and age-related macular degenera-

1. Photocoagulation. The principal lasers used in

tion (ARMD).

ophthalmic therapy are the thermal lasers, which

For sealing of holes in retinal detachment.

depend upon absorption of the laser light by tissue

Complications of laser photocoagulation. These

pigments. The absorbed light is converted into heat,

include: accidental foveal burns, macular oedema and

thus raising the temperature of the target tissue high

macular pucker, pre-retinal fibrosis, haemorrhage from

enough to coagulate and denature cellular elements.

retina and choroid, retinal hole formation, ischaemic

Argon, diode, krypton and diode pump frequency

papillitis, localised opacification of lens and

doubled Nd-YAG lasers are based on this mechanism.

accidental corneal burns.

Modes of action. Photocoagulation is effective in

2. Photodisruption. Laser based on this mechanism

treating ocular diseases by production of a scar,

ionize the electrons of the target tissue producing a

occlusion of vessels, tissue atrophy, and tissue

physical state called plasma. This plasma expands

contraction.

with momentary pressures as high as 10 kilobars,

Therapeutic applications based on photocoagu-

exerting a cutting/incising effect upon the tissues.

lation are as follows:

Nd:YAG laser is based on this mechanism.

Eyelid lesions such as haemangioma.

Therapeutic applications of Nd:YAG laser include

Corneal conditions e.g., reduction of

capsulotomy for thickened posterior capsule and

postoperative astigmatism from cataract sutures—

membranectomy for pupillary membranes. Recently

by Argon laser suturotomy and treatment of

it has also been tried for phacolysis (laser phaco

corneal neovascularisation.

surgery) in phacoemulsification technique of cataract

Laser for glaucoma. Procedures employed include

extraction.

laser iridotomy for narrow-angle glaucoma, argon

3. Photoablation. Lasers based on this mechanism

laser trabeculoplasty

(ALT) for open-angle

produce UV light of very short wavelength which

glaucoma, laser goniopunctures for developmental

breaks chemical bonds of biologic materials,

glaucoma, prophylactic pan-retinal photocoagul-

converting them into small molecules that diffuse

ation to prevent neovascular glaucoma in patients

away. These lasers are collectively called excimer

with retinal hypoxic states (e.g., central retinal

(excited dimer) lasers. These act by tissue modelling.

vein occlusion) and cyclophotocoagulation for

Therapeutic applications of excimer lasers are:

absolute or near absolute glaucoma.

photorefractive keratectomy (PRK), laser assisted in-

Lesions of iris. These include laser coreoplasty

for updrawn pupil, photomydriasis for pathologic

situ keratomileusis (LASIK) for correction of refractive

miotic pupil, laser sphincterotomy and laser

errors and phototherapeutic keratectomy (PTK) for

shrinkage of iris cyst.

corneal diseases such as band-shaped keratopathy.

Lesions of retina and choroid. These form the

most important indications. Common conditions

are:

CRYOTHERAPY IN

Diabetic retinopathy in which pan-retinal

OPHTHALMOLOGY

photocoagulation

(PRP) is carried out for

Cryopexy means to produce tissue injury by

proliferative retinopathy and focal or grid-

application of intense cold (-40^o C to -100^o C). This

photocoagulation for exudative maculopathy.

is achieved by a cryoprobe from a cryo-unit

Peripheral retinal vascular abnormalities such

as Eales’ disease, proliferative sickle cell

(Fig. 18.1).

disease, Coats’ disease and retinopathy of

Principle.Working of cryoprobes is based on the

prematurity.

Joule Thompson principle of cooling.

Intraocular tumours such as retinoblastoma,

Cryounit and probe. The cryounit uses freon, nitrous

malignant melanoma and choroidal haeman-

oxide or carbon dioxide gas as cooling agent.

gioma.

Cryoprobes are available in different sizes such as, 1

432

Comprehensive OPHTHALMOLOGY

Fig. 18.2. Ophthalmic cryo unit.

Uses

1. Lids. Cryosurgery may be used for following

lesions: (i) Cryolysis for trichiasis, (ii) Cryotherapy

for warts and molluscum contagiosum,

(iii)

Cryotherapy for basal cell carcinoma and

Fig. 18.1. Cryoprobes : A and B, for cataract extraction-

haemangioma.

straight and curved, respeativaly; C, for cyclocryopexy;

2. Conjunctiva. Cryotherapy is used for

and D, internal structure

hypertrophied papillae of vernal catarrh.

3. Cornea. Herpes simplex keratitis may be treated

mm for intravitreal use, 1.5 mm straight or curved probe

by cryotherapy.

for cataract extraction, 2.5 mm for retina and 4 mm for

4. Lens. Cryoextraction of the lens used to be the

cyclocryopexy (Fig. 18.2). Temperature produced

best intracapsular technique. However, now-a-

depends upon the size of the cryoprobe tip, duration

days intracapsular cataract extraction (ICCE) is

of freezing process and the gas used.

no more performed.

Modes of action

5. Ciliary body. Cyclocryopexy for absolute

Cryopexy produces the required therapeutic effect

glaucoma and neovascular glaucoma.

by different modes which include tissue necrosis (as

6. Retina. (i) Cryopexy is widely used for sealing

in cyclocryopexy and cryopexy for tumours),

retinal holes in retinal detachment. (ii) Prophylactic

production of adhesions between tissues (e.g.

cryopexy to prevent retinal detachment in certain

between retina, pigment epithelium and choroid in

prone cases. (iii) Anterior retinal cryopexy (ARC) in

retinal detachment), vascular occlusions (as in Coats’

retinal ischaemic disease e.g., retinopathy of

disease) and adherence of the cryoprobe to the iceball

primaturty to prevent neovascularization. (iv) Cryo-

in the tissue (as in cataract extraction).

treatment of retinoblastoma and angioma.

Systemic

CHA 1

Ophthalmology

OCULAR MANIFESTATIONS OF

Disorders of skin and mucous

SYSTEMIC DISEASES

membranes

Introduction

Haematological diseases

Nutritional deficiences

OCULAR ABNORMALITIES IN TRISOMIES

- Xerophthalmia

Systemic infections

ADVERSE OCULAR EFFECTS OF

Metabolic disorders

COMMON SYSTEMIC DRUGS

the eyes due to conjunctival irritation and

OCULAR MANIFESTATIONS OF

vascularisation of the cornea.

SYSTEMIC DISEASES

4. Deficiency of vitamin C. It may be associated

with haemorrhages in the conjunctiva, lids, anterior

INTRODUCTION

chamber, retina and orbit. It also delays wound

healing.

Ocular involvement in systemic disorders is quite

5. Deficiency of vitamin D. It may be associated

frequent. It is imperative for the ophthalmologists as

with zonular cataract, papilloedema and increased

well as physicians to be well conversant with these.

lacrimation.

Many a time, the ocular manifestations may be the

presenting signs and the ophthalmologist will refer

XEROPHTHALMIA

the patient to the concerned specialist for diagnosis

They term xerophthalmia is now reserved (by a joint

and/or management of the systemic disease. While,

WHO and USAID Committee, 1976) to cover all the

in other cases the opinion for ocular involvement may

ocular manifestations of vitamin A deficiency,

be sought for by the physician who knows to look

including not only the structural changes affecting

for it.

the conjunctiva, cornea and occasionally retina, but

Ocular lesions of the common systemic disorders

also the biophysical disorders of retinal rods and

are enumerated and a few important ones are

cones functions.

described here.

Etiology

OCULAR MANIFESTATIONS OF NUTRITIONAL

It occurs either due to dietary deficiency of vitamin

DEFICIENCES

A or its defective absorption from the gut. It has long

1. Deficiency of vitamin A. Ocular manifestations of

been recognised that vitamin A deficiency does not

vitamin A deficiency are referred to as

occur as an isolated problem but is almost invariably

xerophthalmia.

accompanied by protein-energy malnutrition (PEM)

2. Deficiency of vitamin B₁ (thiamine). It can cause

and infections.

corneal anaesthesia, conjunctival and corneal

dystrophy and acute retrobulbar neuritis.

WHO classification (1982)

3. Deficiency of vitamin B₂

(riboflavin). It can

The new xerophthalmia classification (modification

produce photophobia and burning sensation in

of original 1976 classification) is as follows:

434

Comprehensive OPHTHALMOLOGY

XN Night blindness

X1A Conjunctival xerosis

X1B Bitot’s spots

Corneal xerosis

X3A

Corneal ulceration/keratomalacia affecting

less than one-third corneal surface

X3B Corneal ulceration/keratomalacia affecting

more than one-third corneal surface.

XS Corneal scar due to xerophthalmia

XF Xerophthalmic fundus.

Clinical features

1. X N (night blindness). It is the earliest symptom of

xerophthalmia in children. It has to be elicited by

taking detailed history from the guardian or relative.

2. X1A (conjunctival xerosis). It consists of one or

Fig. 19.2. Xerophthalmia, stage XIB: Bitot spots.

more patches of dry, lustreless, nonwettable

conjunctiva (Fig. 19.1), which has been well described

4. X2 (corneal xerosis). The earliest change in the

as ‘emerging like sand banks at receding tide’ when

cornea is punctate keratopathy which begins in the

the child ceases to cry. These patches almost always

lower nasal quadrant, followed by haziness and/or

involve the inter-palpebral area of the temporal

granular pebbly dryness (Fig. 19.3). Involved cornea

quadrants and often the nasal quadrants as well. In

lacks lustre.

more advanced cases, the entire bulbar conjunctiva

5. X3A and X3B (corneal ulceration/keratomala-

may be affected. Typical xerosis may be associated

cia), Stromal defects occur in the late stage due to

with conjunctival thickening, wrinkling and

colliquative necrosis and take several forms. Small

pigmentation.

ulcers (1-3 mm) occur peripherally; they are

characteristically circular, with steep margins and are

sharply demarcated (Fig. 19.4). Large ulcers and areas

of necrosis may extend centrally or involve the entire

cornea. If appropriate therapy is instituted immediately,

stromal defects involving less than one-third of

corneal surface (X3A) usually heal, leaving some

useful vision. However, larger stromal defects (X3B)

(Fig. 19.5) commonly result in blindness.

Fig. 19.1. Xerophthalmia, stage XIA: Conjunctival xerosis.

3. X1B (Bitot’s spots). It is an extension of the xerotic

process seen in stage X1A. The Bitot’s spot is a

raised, silvery white, foamy, triangular patch of

keratinised epithelium, situated on the bulbar

conjunctiva in the inter-palpebral area (Fig. 19.2). It is

usually bilateral and temporal, and less frequently

Fig. 19.3. Xerophthalmia, stage X2: Corneal xerosis.

nasal.

SYSTEMIC OPHTHALMOLOGY

435

Fig. 19.4. Xerophthalmia, stage X3A: Keratomalacia

Fig. 19.6. Xerophthalmia, stage XS: Corneal scars.

involving less than one-third of corneal surface.

Fig. 19.5. Xerophthalmia, stage X3B: Keratomalacia

involving more than one-third of corneal surface.

Fig. 19.7. Xerophthalmia, stage XF: Xerophthalmic fundus.

6. XS (corneal scars). Healing of stromal defects

2. Vitamin A therapy. Treatment schedules apply to

results in corneal scars of different densities and sizes

all stages of active xerophthalmia viz. XN, X1A, X1B,

which may or may not cover the pupillary area (Fig.

X2, X3A and X3B. Oral administration is the

19.6). A detailed history is required to ascertain the

recommended method of treatment. However, in the

cause of corneal opacity.

presence of repeated vomiting and severe diarrhoea,

7. XFC (Xerophthalmic fundus). It is characterized

intramuscular injections of water-miscible preparation

by typical seed-like, raised, whitish lesions scattered

should be preferred. The WHO recommended

uniformly over the part of the fundus at the level of

schedule is as given below:

optic disc (Fig. 19.7).

i. All patients above the age of

1 year (except

Treatment

women of reproductive age): 200,000 IU of vitamin

It includes local ocular therapy, vitamin A therapy

A orally or 100,000 IU by intramuscular injection

and treatment of underlying general disease.

should be given immediately on diagnosis and

1. Local ocular therapy. For conjunctival xerosis

repeated the following day and 4 weeks later.

artificial tears (0.7 percent hydroxypropyl methyl

ii. Children under the age of 1 year and children

cellulose or 0.3 percent hypromellose) should be

instilled every 3-4 hours. In the stage of keratomalacia,

of any age who weigh less than 8 kg should be

full-fledged treatment of bacterial corneal ulcer

treated with half the doses for patients of more

should be instituted (see pages 120-123).

than 1 year of age.

436

Comprehensive OPHTHALMOLOGY

iii. Women of reproductive age, pregnant or not: (a)

2. Medium-term approach. It includes food

Those having night blindness (XN), conjunctival

fortification with vitamin A.

xerosis (X1A) and Bitot’s spots (X1B) should be

3. Long-term approach. It should be the ultimate

treated with a daily dose of 10,000 IU of vitamin

aim. It implies promotion of adequate intake of vitamin

A orally (1 sugar coated tablet) for 2 weeks.

A rich foods such as green leafy vegetables, papaya

(b) For corneal xerophthalmia, administration of

and drum- sticks (Fig. 19.8). Nutritional health

full dosage schedule (described for patients above

education should be included in the curriculum of

1 year of age) is recommended.

school children.

3. Treatment of underlying conditions such as PEM

and other nutritional disorders, diarrhoea,

dehydration and electrolyte imbalance, infections and

parasitic conditions should be considered

simultaneously.

Prophylaxis against xerophthalmia

The three major known intervention strategies for the

prevention and control of vitamin A deficiency are:

1. Short-term approach. It comprises periodic

administration of vitamin A supplements. WHO

recommended, universal distribution schedule of

vitamin A for prevention is as follows:

Infants 6-12

100,000 IU orally every

months old and

3-6 months.

Fig. 19.8. Rich sources of vitamin A.

any older children

who weigh less

Note. The short-term approach has been mostly in

than 8 kg.

vogue especially in Asia. The best option perhaps is

ii.

Children over

200,000 IU orally every

a combination of all the three methods with a gradual

1 year and under

6 months.

weaning away of the short-term approach.

6 years of age

OCULAR MANIFESTATIONS OF SYSTEMIC

iii. Lactating

20,000 IU orally once at

INFECTIONS

mothers

delivery or during the next

2 months. This will raise

A. VIRAL INFECTIONS

the concentration of vitamin

Measles. Ocular lesions are: catarrhal conjunctivitis,

A in the breast milk and

Koplik’s spots on conjunctiva, corneal ulceration,

therefore, help to protect

optic neuritis and retinitis.

the breastfed infant.

Mumps. Ocular involvement may occur as

iv. Infants less

50,000 IU orally should

conjunctivitis, keratitis, acute dacryoadenitis and

than 6 months

be given before they

uveitis.

old, not being

attain the age of 6

Rubella. Ocular lesions seen in rubella (German

breastfed.

months.

measles) are congenital microphthalmos, cataract,

A revised schedule of vitamin A supplements being

glaucoma, chorioretinitis and optic atrophy.

followed in India since August 1992, under the

Whooping cough. There may occur subconjunctival

programme named as ‘Child Survival and Safe

haemorrhages and rarely orbital haemorrhage leading

Motherhood (CSSM)’ is as follows:

to proptosis.

First dose (1 lakh I.U.)—at 9 months of age along

with measles vaccine.

Ocular involvement in AIDS

Second dose (2 lakh I.U.)—at 18 months of age

AIDS (Acquired Immune Deficiency Syndrome) is

along with booster dose of DPT/OPV.

caused by Human immunodeficiency virus (HIV)

Third dose (2 lakh I.U.)—at 2 years of age.

which is an RNA retrovirus.

SYSTEMIC OPHTHALMOLOGY

437

Modes of spread include:

2. Usual ocular infections. These are also seen in

Sexual intercourse with an infected person,

healthy people, but occur with greater frequency and

Use of infected hypodermic needles,

produce more severe infections in patients with AIDS.

Transfusion of infected blood and

These include:

Transplacental spread to foetus from the infected

Herpes zoster ophthalmicus,

mothers.

Herpes simplex infections,

Pathogenesis of AIDS. The HIV infects T-cells, T-

Toxoplasmosis (chorioretinitis),

helper cells, macrophages and B-cells and thus

Ocular tuberculosis, syphilis and fungal corneal

interferes with the mechanism of production of

ulcers.

immune bodies thereby causing immunodeficiency.

3. Opportunistic infections of the eye. These are

Immune deficiency renders the individuals prone

caused by microorganisms which do not affect normal

to various infections and tumours, which involve

patients. They can infect someone whose cellular

multiple systems and finally cause death.

immunity is suppressed by HIV infection or by other

Ocular manifestations. These occur in about 75

causes such as leukaemia. These include:

percent of patients and sometimes may be the

cytomegalovirus (CMV) retinitis (see page 253 Fig

presenting features of AIDS in an otherwise healthy

11.5), candida endophthalmitis, cryptococcal

person or the patient may be a known case of AIDS

when his eye problems occur. Ocular lesions of AIDS

infections and pneumocystis carini, choroiditis.

may be classified as follows:

4. Unusual neoplasms. Kaposi’s sarcoma is a

1. Retinal microvasculopathy. It develops from

malignant vascular tumour which may appear on the

vaso-occlusive process which may be either due to

eyelid or conjunctiva as multiple nodules. It is seen

direct toxic effects of virus on the vascular

in about 3 percent cases of AIDS. Burkitt’s lymphoma

endothelium or immune complex deposits in the

of the orbit is also seen in a few patients.

precapillary arterioles.

5. Neuro-ophthalmic lesions. These are thought to

It is characterised by non-specific lesions (Fig.

be due to CMV or other infections of the brain. These

19.9):

include isolated or multiple cranial nerve palsies

Multiple ‘cotton-wool spots’ occur in 50 percent

resulting in paralysis of eyelids, extraocular muscles,

cases,

loss of sensory supply to the eye and optic nerve

Superficial and deep retinal hemorrhages occur in

involvement causing loss of vision.

15-40 percent cases.

Microaneurysms and telangiectasia may also be

Management. It consists of the measures directed

seen rarely.

against the associated infection/lesions. For example:

CMV infections can be treated by zidovudine,

gancyclovir and foscarnet (see page 422).

Kaposi’s sarcoma responds to radiotherapy.

Horpes zoster ophthalmicus, is treated by

acyclovir.

B. BACTERIAL INFECTIONS

1. Septicaemia. Ocular involvement may occur in

the form of metastatic retinitis, uveitis or

endophthalmitis.

2. Diphtheria. There may occur: membranous

conjunctivitis, corneal ulceration, paralysis of

accommodation and paralysis of extraocular

muscles.

3. Brucellosis. It may involve the eye in the form of

Fig. 19.9. Retinopathy in AIDS.

iritis, choroiditis and optic neuritis.

438

Comprehensive OPHTHALMOLOGY

Gonococcal ocular lesions are: ophthalmia

OCULAR MANIFESTATIONS OF COMMON

neonatorum, acute purulent conjunctivitis in adults

ENDOCRINAL AND METABOLIC DISORDERS

and corneal ulceration.

Gout

Meningococcal infection may be associated with:

Ocular lesions of gout include:

metastatic conjunctivitis, corneal ulceration,

Episcleritis,

paresis of extraocular muscles, optic neuritis and

Scleritis, and

metastatic endophthalmitis or panophthalmitis.

Uveitis.

Typhoid fever. It may be complicated by optic

neuritis and corneal ulceration due to

Diabetes mellitus

lagophthalmos.

Ocular involvement in diabetes is very common.

Tuberculosis. Ocular lesions seen are

Structure-wise ocular lesions are as follows:

granulomatous conjunctivitis, phlyctenular

1. Lids. Xanthelasma and recurrent stye or internal

keratoconjunctivitis, interstitial keratitis,

hordeolum

nongranulomatous and granulomatous uveitis,

2. Conjunctiva. Telangiectasia, sludging of the blood

Eales’ disease, optic atrophy (following chiasmal

in conjunctival vessels and subcon-junctival

arachnoiditis secondary to meningitis), and

haemorrhage

papilloedema (due to raised intracranial pressure

3. Cornea. Pigment dispersal at back of cornea,

following intracranial tuberculoma).

decreased corneal sensations (due to trigeminal

Syphilitic lesions (acquired) seen in primary stage

neuropathy), punctate kerotapathy, Descemet’s

are conjunctivitis and chancre of conjunctiva. In

folds, higher incidence of infective corneal ulcers

secondary stage there may occur iridocyclitis.

and delayed epithelial healing due to abnormality

Tertiary stage lesions include chorioretinitis and

in epithelial basement membrane

gummata in the orbit. Neurosyphilis is associated

4. Iris. Rubeosis iridis (neovascularization)

with optic atrophy and pupillary abnormalities.

5. Lens. Snow-flake cataract in patients with IDDM,

Ocular lesions of congenital syphilis are: interstitial

keratitis, iridocyclitis and chorioretinitis.

posterior subcapsular cataract, early onset and

Leprosy. Ocular lesions of leprosy include

early maturation of senile cataract

cutaneous nodules on the eyelids, madarosis,

6. Vitreous. Vitreous haemorrhage and fibre- vascular

interstitial keratitis, exposure keratitis,

proliferation secondary to diabetic retinopathy

granulomatous uveitis and dacryocystitis.

7. Retina. Diabetic retinopathy and lipaemia retinalis

(see page 259).

C. PARASITIC INFECTIONS

8. Intraocular pressure. Increased incidence of

1. Toxoplasmosis is known to produce necrotising

POAG, neovascular glaucoma and hypotony in

chorioretinitis (see page 157).

diabetic ketoacidosis (due to increased plasma

2. Taenia echinococcus infestation may manifest as

bicarbonate levels)

hydatid cyst of the orbit, vitreous and retina.

9. Optic nerve. Optic neuritis

3. Taenia solium infestation. Cysticercus cysts are

10. Extraocular muscles. Ophthalmoplegia due to

known to involve conjunctiva, vitreous, retina,

diabetic neuropathy

orbit and extra-ocular muscles.

11. Changes in refraction. Hypermetropic shift in

4. Toxocara infestation may be associated with

hypoglycemia, myopic shift in hyperglycemia and

endophthalmitis (see page 158).

decreased accommodation

5. Onchocerciasis is a common cause of blindness

Galactosemia

in African countries. Its ocular features include

sclerosing keratitis, uveitis, chorioretinitis and

It is usually associated with congenital cataract (page

optic neuritis invariably ending in optic atrophy.

181).

D. FUNGAL INFECTIONS

Homocystinuria

It is associated with bilateral subluxation of lens (page

Systemic fungal infections may be associated with

202).

corneal ulceration and endophthalmitis.

SYSTEMIC OPHTHALMOLOGY

439

Mucopoly saccharidosis

OCULAR MANIFESTATIONS OF

Ocular lesions include:

HAEMATOLOGICAL DISEASES

Corneal opacification,

1. Anaemias. Anaemic retinopathy may occur in

Pigmentary retinopathy,

severe anaemia of any etiology (see page 264).

Glaucoma, and

2. Leukaemias. Ocular involvement in leukaemias

Optic atrophy

may occur in the form of:

Proptosis due to leukaemic deposits in the orbital

Hyperthyroidism

tissue.

Ocular lesions include:

Leukaemic retinopathy is of common occurrence

Thyroid ophthalmopathy (see page 390)

in lymphocytic as well as myeloid leukaemias

Superior limbic keratoconjunctivitis (page 111),

(see page 264).

and

3. Sickle cell disease. Ocular involvement may occur

Optic disc oedema

as:

Dilated conjunctival vessels and

Hypoparathyroidism

Sickle cell retinopathy (see page 264)

Ocular lesions include:

4. Lymphomas may cause following ocular lesions:

Fasciculation

Lid and/or orbital deposits, and

Cataract and

Uveitis

Optic disc oedema

Wilson disease

OCULAR ABNORMALITIES IN

Ocular lesions include:

TRISOMIES

Kayser - Fleisher ring

Sunflower cataract

Trisomy 13 (D Trisomy or Patau Syndrome)

OCULAR MANIFESTATIONS OF COMMON

Microphthalmos

DISORDERS OF SKIN AND MUCOUS

Colobomas (almost 100%)

MEMBRANES

Retinal dysplasia

Cataract

1. Atopic dermatitis. It may be associated with

Corneal opacities

conjunctivitis, keratoconus and cataract.

Optic nerve hypoplasia

2. Rosacea. Its ocular lesions include blepharitis,

Cyclopia

conjunctivitis, keratitis and rosacea pannus.

Intra-ocular cartilage

3. Dermatitis herpetiformis. Its ocular complications

include recurrent bullae, ulceration and

Trisomy 18 (E trisomy or Edwards syndrome)

cicatrization.

Blepharophimosis

4. Epidermolysis bullosa. Ocular complications,

Ptosis

Epicanthal fold

when they occur, take the form of cicatrizing

Hypertelorism

conjunctivitis and keratitis.

Microphthalmos

5. Stevens-Johnson syndrome. Stevens-Johson

Uveal coloboma

syndrome is an acute illness often caused by

Congenital glaucoma

hypersensitivity to drugs, particularly

Corneal opacities

sulphonamides. It is characterized by acute

ulceration of the conjunctiva and other mucous

Trisomy 21 (G Trisomy or Down’s syndrome)

membranes like that of mouth and vagina.

Upward slanting palpebral fissure

(Mongoloid

Conjunctival ulceration is followed by cicatrizing

slant)

conjunctivitis. The clinical picture at this stage is

Almond-shaped palpebral fissure

the same as in ocular pemphigoid.

Epicanthus

440

Comprehensive OPHTHALMOLOGY

Telecanthus

Blue sclera

Narrowed interpupillary distance

Eccentric pupils

Esotropia (35% cases)

Cataract

High refractive errors

Colour blindness

Cataract

Pigmentary disturbances of fundus

Iris hypoplasia

Keratoconus

ADVERSE OCULAR EFFECTS OF

Ocular abnormalities in chromosomal deletion

COMMON SYSTEMIC DRUGS

syndromes

Cri-du-Chat syndrome (5p.)

C.V.S. drugs

Hypertelorism

Digitalis: Disturbance of colour vision, scotomas

Epicanthus

Quinidine: Optic neuritis (rare)

Antimongoloid slant

Thiazides: Xanthopsia (yellow vision), Myopia

Strabisums

Carbonic anhydrase inhibitors: Ocular hypotony,

Cri-du-Chat syndrome (11 p.)

Transient myopia

Aniridia

Amiodarone: Corneal deposits

Glaucoma

Oxprenolol: Photophobia, Ocular irritation

Foveal hypoplasia

G.I.T. drugs

Nystagmus

Anticholinergic agents: Risk of angle-closure

Ptosis

glaucoma due to mydriasis, Blurring of vision

Cri-du-Chat syndrome (13 q.)

due to cycloplegia (Occasional).

Retinoblastoma

Hypertelorism

C.N.S. drugs

Microphthalmos

Barbiturates: Extraocular muscle palsies with

Epicanthus

diplopia, Ptosis, Cortical blindness

Ptosis

Chloral hydrate: Diplopia, Ptosis, Miosis

Coloboma

Phenothiazines: Deposits of pigment in

Cataract

conjunctiva, cornea, lens and retina, Oculogyric

De Grouchy syndrome (18q.)

crisis

Hypertelorism

Amphetamines: Widening of palpebral fissure,

Epicanthus

Dilatation of pupil, Paralysis of ciliary muscle

Ptosis

with loss of accommodation

Strabismus

Monoamine oxidase inhibitors: Nystagmus,

Myopia

Extraocular muscle palsies, Optic atrophy

Glaucoma

Tricyclic agents: Pupillary dilatation (glaucoma

Microphthalmos (with or without cyst)

risk), Cycloplegia

Coloboma

Phenytoin: Nystagmus, Diplopia, Ptosis, Slight-

Optic atrophy

blurring of vision (rare)

Corneal opacity

Neostigmine: Nystagmus, Miosis

Turner syndrome (XO)

Morphine: Miosis

Antimongoloid slant

Haloperidol: Capsular cataract

Epicanthus

Lithium carbonate: Exophthalmos, Oculogyric

Ptosis

crisis

Strabismus

Diazepam: Nystagmus.

SYSTEMIC OPHTHALMOLOGY

441

Hormones

Amoebicides

Female sex hormones

Diiodohydroxy quinoline: Subacute myelo optic

neuropathy (SMON), optic atrophy

Retinal artery thrombosis

Retinal vein thrombosis

Chemotherapeutic agents

Papilloedema

Sulfonamides: Stevens-Johnson syndrome

Ocular palsies with diplopia

Ethambutol: Optic neuritis and atrophy

Nystagmus

Isoniazid: Optic neuritis and optic atrophy

Optic neuritis and atrophy

Retinal vasculitis

Heavy metals

Scotomas

Gold salts: Deposits in the cornea and conjunctiva

Migraine

Lead: Optic atrophy, Papilloedema, Ocular palsies

Mydriasis

Cyloplegia

Chelating agents

Macular oedema

Penicillamine: Ocular pemphigoid, Ocular

Corticosteroids

neuritis, Ocular myasthenia

Cataract (posterior subcapsular)

Oral hypoglycemic agents

Local immune suppression causing susceptibility

to viral

(herpes simplex), bacterial and fungal

Chloropropamide: Transient change in refractive

infections

error, Diplopia, Stevens-Johnson syndrome

Steroid-induced glaucoma

Vitamins

Antibiotics

Vitamin A

Chloramphenicol: Optic neuritis and optic

Papilloedema

atrophy

Streptomycin: Optic neuritis

Retinal haemorrhages

Tetracycline: Pseudotumour cerebri, Transient

Loss of eyebrows and eyelashes

myopia

Nystagmus

Diplopia and blurring of vision

Antimalarial

Vitamin D

Chloroquine

Band-shaped keratopathy

Macular changes (Bull’s eye maculopathy)

Central scotomas

Antirheumatic agents

Pigmentary degeneration of the retina

Salicylates: Nystagmus, Retinal haemorrhages,

Chloroquine keratopathy

Cortical blindness (rare)

Ocular palsies

Ptosis

Indomethacin: Corneal deposits

Electroretinographic depression

Phenylbutazone: Retinal haemorrhages

Community

CHA 2

Ophthalmology

INTRODUCTION

Vision 2020: Right to Sight

Vision for the future (VFTF)

BLINDNESS AND ITS CAUSES

Definition of blindness

NATIONAL PROGRAMME FOR CONTROL

Magnitute of blindness

OF BLINDNESS IN INDIA

Global blindness

Objectives

Blindness in India

Plan of action and activities

Causes of blindness

Basic programme components

Global blindness

Programme organization

Blindness in India

Strategic plan for Vision 2020: Right

Developing versus developed

to Sight in India

countries

Role of eye camps in prevention of

GLOBAL INITIATIVES FOR

blindness

PREVENTION OF BLINDNESS

Eye banking

Global programme for prevention of

blindness

Rehabilitation of the blind

INTRODUCTION

BLINDNESS AND ITS CAUSES

In recent years, community ophthalmology has

DEFINITION OF BLINDNESS

developed as an important branch of community

Different definitions and terms for blindness such as

medicine. Its activities emphasize the prevention of

total blindness, economic blindness, legal blindness

ocular diseases and visual impairment; reduction of

and social blindness are in vogue in different

ocular disability; and promotion of ocular health,

countries so much so that 65 definitions of blindness

quality of life and efficiency of a group of people at

are listed in a WHO publication (1966).¹ In

the community level. Thus, it can be defined as a

ophthalmology, the term blindness strictly refers to

system (rather than a branch of community medicine)

the inability to perceive light (PL absent).

which utilises the full scope of ophthalmic knowledge

WHO definition of blindness. In order to have

and skill, methodology of public health and services

comparable national and international statistics, the

of other medical and non-medical agencies to promote

WHO in 1972 proposed a uniform criterion and defined

ocular health and prevent blindness at the community

level with an active, recognised and crucial role of

blindness as, “Visual acuity of less than 3/60

community participation.

(Snellen) or its equivalent”.² In order to facilitate

The concept of community ophthalmology has

the screening of visual acuity by non-specialised

become more relevant and essential to achieve the

persons, in the absence of appropriate vision charts,

goal of ‘Vision 2020: The Right to Sight’ and to,

the WHO in 1979 added the “Inability to count

accomplish the theme behind ‘Vision for the Future

fingers in day-light at a distance of 3 metres” to

(VFTF)’.

indicate vision less than 3/60 or its equivalent.³

444

Comprehensive OPHTHALMOLOGY

Visual filed less than 10º, irrespective of the level of

MAGNITUDE OF BLINDNESS

visual acuity in also labelled as blindness (WHO,

Magnitude of global blindness

1977⁴).

The number of blinds across the globe is not within

Other definitions of blindness in vogue are:

the exact realms of counts. However, from time to

Economic blindness: vision in better eye <6/60

time, the World Health Organization (WHO) provides

to 3/60

the estimates. At present, WHO estimated:

Social blindness: Vision in better eye <3/60 to 1/

180 million people worldwide are visually disabled

of whom nearly 45 million are blind.

Legal blindness: Vision in better eye <1/60 to

About 80% of blindness is avoidable, i.e., either

perception light

curable or potentially preventable.

Total blindness: No light perception (PL -ve).

About 32% of the world’s blind people are in the

Categories of visual impairment. In the Ninth

age bracket of 45-59 years but a big majority i.e.,

Revision (1977) of the International Classification of

about 58% are over 60 years of age.⁵

Diseases (ICD), the visual impairment (maximum vision

Geographial distribution of global blindness. About

less than 6/18 Snellen) has been divided into 5

90% of the world’s blinds live in developing countries

categories. Categories 1 and 2 constitute “low vision”

and around 60% of them reside in sub-Saharan Africa,

and categories 3, 4 and 5 constitute “blindness”

China and India. There is a significant difference in

(Table 20.1). Patients with the visual fields between

the level of blindness in the developing as compared

5° and 10° are placed in category 3 and those with

to the developed countries of the world, as there are:

less than 5° in category 4.

3 blind people/1000 population in developed

countries of Europe, America and Japan,

Table 20.1. Categories of visual impairment

(WHO, 1977)⁴

9 blind people /1000 population in Asia, and

12 blind people /1000 population in Africa.

Category of visual

Level of visual acuity (Snellen)

Regional burden of blindness. For having an easy

impairment

means of comparison among different regions of the

Normal vision

6/6 to 6/18

world, a ratio referred to as the Regional Burden of

Low vision

Less than 6/18 to 6/60

Blindness (RBB) was evolved. This means the ratio

Less than 6/60 to 3/60

of the proportion of the number of blind in a particular

Less than 3/60 (FC at 3 m)

region to the global number of blind and the

to 1/60 (FC at 1m) or

proportion of the regional population to the world

Blindness

visual field between 5°and 10°

population. The sub-Saharan Africa, India and other

Less than 1/60 (FC at 1 m) to

Asia and Islands have RBB ratio greater than unity ⁶.

light perception or visual field

This indicates that in these regions, the burden of

less than 5°

blindness is to be taken into special consideration in

No light perception

terms of fixing priorities on a global scale.

Avoidable blindness. The concept of avoidable

Magnitude of blindness in India

blindness includes both preventable blindness and

While the problem of blindness is global, its

curable blindness.

magnitude is much higher in India. Of the estimated

Preventable blindness is that which can be easily

45 million, India alone has 8.9 million blind people,

prevented by attacking the causative factor at an

(2001-2002 survey, NPCB), which comes to about one-

appropriate time. For example, corneal blindness

fifth of the total in the world. The prevalence of

due to vitamin A deficiency and trachoma can be

blindness in India, as determined by the three major

prevented by timely measures.

surveys conducted in the last 3 decades is as below:

Curable blindness is that in which vision can be

Prevalence

Source

restored by timely intervention. For example,

1.38%

ICMR (1971 - 74)⁷

cataract blindness can be cured by surgical

1.49%

WHO-NPCB (1986-89)⁸

1.1%

NPCB (2001-2002)⁹

treatment.

COMMUNITY OPHTHALMOLOGY

445

Factors for higher prevalence of blindness in India

continue to change, though the major causes of

are:

blindness still continue to be the same (Table 20.2).^7,8,9

1. Gross inadequacy of ophthalmic personnel.

Developed countries versus developing countries

2. Lack of availability of services near the homes of

the people and the problem of communication.

The main causes of blindness in developed countries

3. Under-utilisation of available manpower.

are different from those of developing countries.

4. Rural/urban imbalance in availability of services.

In developed countries, 50 percent of all blindness

5. Lack of knowledge and concern, malnutrition,

is because of age related macular degeneration

lack of eyecare, superstitions and ignorance.

(ARMD), while another 10-20 percent each is

6. Prevalence of infections.

because of glaucoma, diabetic retinopathy and

7. Man-made blindness due to quack practice and

cataract.

home remedies.

In developing countries the frequent causes are

cataract, infectious diseases, xerophthalmia,

CAUSES OF BLINDNESS

injuries, glaucoma, and onchocerciasis.

Causes of global blindness

Major causes of blindness and the estimated number

GLOBAL INITIATIVES FOR

of blinds due to them are as under⁵:

PREVENTION OF BLINDNESS

Cataract

19 million

Glaucoma

6.4 million

The concept of avoidable blindness (i.e., preventable

Trachoma

5.6 million

or curable) has gained increasing recognition during

Childhood blindness

the last three decades. Inter-national Agency for the

including xerophthalmia

>1.5 million

Prevention of Blindness (IAPB) formed in 1974, is an

Onchocerciasis

0.29 million

inter-national non-governmental agency which has a

Others

10 million

close and complementary relationship with WHO (an

Causes of blindness in India

international inter-governmental agency in the field

The problem of blindness in India is not only of its

of prevention of blindness).

gigantic size, but also of its causes, which are largely

The major global initiatives taken for prevention

preventable or curable with the present available

of blindness are:

knowledge and skill. Three major population based

Global programme for prevention of blindness.

surveys have been carried out in India to estimate

the magnitude and causes of blindness. These

Vision 2020: The Right to Sight, and

surveys have shown that trends in blindness

Vision for the future (VFTF).

Table 20.2: Major causes of blindness in India.

NPCB Survey (2001-02)⁹

WHO-NPCB Survey (1986-89)⁸

ICMR Survey (1971-74)⁷

Disease

Percent

Disease

Percent

Disease

Percent

condition

blindness

condition

blindness

condition

blindness

Cataract

62.6

Cataract

80.1

Cataract

Refractive errors

19.7

Refractive errors

7.35

Malnutrition

Glaucoma

5.8

Glaucoma

1.7

Glaucoma

0.5

Posterior segment

Trachoma and

disorders

4.7

Trachoma

0.39

associated infections

Surgical complications

1.2

Aphakic blindness

4.67

Injuries

1.2

Corneal blindness

0.9

Corneal opacity

1.52

Small pox seaquele

Others

5.0

Others

4.25

Others

446

Comprehensive OPHTHALMOLOGY

GLOBAL PROGRAMME FOR CONTROL OF

STRATEGIC APPROACHES: GLOBAL

BLINDNESS

PROSPECTIVE

The WHO launched a global programme for

Strategic approaches of Vision 2020: Right to Sight

prevention of blindness in 1978. In accordence with

(Global prospective) are:

which many countries have already come up with a

Disease prevention and control,

‘National Blindness Control Programme’.

Training of eye health personnel,

Strengthening of existing eye care infrastructure,

Control strategies suggested by WHO include:

Use of appropriate and affordable technology,

1. Assessment of common blinding disorders at

and

local, regional and national levels.

Mobilization of resources.

2. Establishment of national level programmes for

control of blindness suited to the national and

Disease prevention and control

local needs.

Globally, WHO has identified five major blinding eye

3. Training of eye care providers.

conditions, for immediate attention to achieve the

4. Operational research to improve and apply

goals of Vision 2020, which are:

appropriate technology.

Cataract

VISION 2020: THE RIGHT TO SIGHT

Childhood blindness,

‘Vision 2020: The Right to Sight’,¹⁰ is a global initiative

Trachoma,

launched by WHO in Geneva on Feb. 18,1999 in a

Refractive errors and low vision, and

broad coalition with a ‘Task Force of International

Onchocerciasis.

Non-Governmental Organisations (NGOs)’ to combat

These conditions have been chosen on the basis

the gigantic problem of blindness in the world.

of their contribution to the burden of blindness,

Partners of Vision 2020: Right to Sight include:

feasibility and affordability of interventions to control

World Health Organisation (WHO),

them. Each country will decide on its priorities based

II.

Task Force of International NGOs, which has

on the magnitude of specific blinding conditions in

following members:

that country.

International Agency for Prevention of

Cataract

Blindness (IAPB)

Cataract remains the single largest cause of blindness.

Christopher Blindness Mission (CBM)

There is an estimated figure of 19 million people

Helen Keller International

worldwide who are blind because of curable cataract.

ORBIS International

Aim under ‘Vision 2020’ is to eliminate avoidable

Sight Savers International

blindness due to cataract, i.e., to decrease the number

Al Noor Foundation

of cataract blinds in the world from 19 million to zero

International Federation of Ophthalmological

by the year 2020.

Societies

Strategy to achieve the aim is to increase the cataract

Lions Clubs International Foundation

surgery rate (CSR), i.e., number of cataract surgeries

Operation Eye Sight Universal

per million population per year as below:

The Carter Centre

Objective of vision 2020. Objective of this new global

Year

Global cataract

Global number of

initiative is to eliminate avoidable blindness by the

surgical rate

cataract operation

year 2020 and to reduce the global burden of

(million)

blindness which currently affects an estimated 45

2000

million people worldwide.

2010

3000

Implementation of vision 2020. Vision 2020 will be

2020

4000

implemented through four phases of five year plans,

the first one started in 2000 and second in 2005. The

Emphasis is to be placed on achieving:

two subsequent phases of implementation will

High success rates in terms of restored vision

commence from 2010 and 2015, respectively.

and quality-of-life outcome.

COMMUNITY OPHTHALMOLOGY

447

Affordable and accessible services

Surgery to correct lid deformity and prevent

Measures to overcome barriers and increased

blindness,

use of services.

Antibiotics for acute infections and community

control,

Childhood blindness

Facial hygiene, and

Childhood blindness is considered a priority area due

Environmental change including improved

to the number of years of blindness that ensues.

access to water and sanitation and health

Prevalence is 0.5-1 per 1000 children aged 0-15 years.

education.

There are 1.5 million blind children estimated in the

Elimination of blindness due to trachoma is

considered feasible, eradication of trachoma is not.

world of whom 1 million live in Asia and 3 lakhs in

Trachoma has disappeared from North America and

Africa. There are 5 lakh children going blind each

Europe because of improved socio-economic

year (one per minute) also.

conditions and hygiene. Research needs include

Causes of childhood blindness vary from place to

validation of rapid community assessment

place and change over time. The main causes include:

techniques, identification of barriers to the

Vitamin A deficiency, measles, conjunctivitis,

acceptance of preventive surgical procedure, studying

ophthalmia neonatorum, congenital cataract and

effectiveness of annual treatment cycles and cost-

retinopathy of prematurity (ROP).

effective studies. W.H.O. has organized an Alliance

Aim is to eliminate avoidable causes of childhood

for Global Elimination of Trachoma by the year 2020

blindness by the year 2020.

(GET 2020).

Strategies and activitis under the global initiative

Refractive errors and low vision

vision 2020 include:

Aim is to eliminate visual impairment (visual acuity

I. Elimination of preventable blindness by:

less than 6/18) and blindness due to refractive errors

Measles immunisation,

or other causes of low vision. It is estimated that

Vitamin A supplementation (see page 436),

there are 35 million people in the world who require

Monitoring use of oxygen in the premature

low vision care.

new born,

Strategies recomended under ‘Vision 2020’ initiative

Avoidance of harmful traditional practices,

include:

Promoting school screening programmes for

Screening to identify individuals with poor vision

diagnosis and management of common

which can be improved by spectacles or other

conditions like refractive errors and trachoma

optical devices.

in endemic areas, and

Refraction services to be made available to

individuals identified with significant refractive

Promoting eye health education in schools.

errors.

II. Management of surgically avoidable causes of

Ensure optical services to provide affordable

childhood blindness such as cataract, glaucoma,

spectacles for individuals with significant

and retinopathy of prematurity (ROP).

refractive errors.

Low vision services and low vision aids to be

Trachoma blindness

provided for all those in need.

Trachoma is a leading cause of preventable blindness

Onchocerciasis

worldwide with an estimated 5.9 million persons blind

Onchocerciasis (river blindness) is known to be

or at immediate risk because of trichiasis.¹⁰ The

endemic in 37 countries. An estimated 17 million people

disease accounts for nearly one-sixth of the global

are infected with onchocerciasis. Approximately 0.3-

burden of blindness. In India, blindness due to

0.6 million people are blind from the disease. About

trachoma (0.39%, WHO-NPCB 1986-89) is on the

95% of infected persons reside in Africa, where the

decline when compared with previous figures (20%,

disease is most severe along the major rivers in 30

ICMR 1975).

countries. Outside Africa, the disease occurs in

Effective interventions have been demonstrated

Mexico, Guatemala, Ecuador, Columbia, Venezuela and

in developing nations using the SAFE strategy:

Brazil in the America, and in Yemen in Asia.

448

Comprehensive OPHTHALMOLOGY

Aim is to eliminate blindness due to onchocerciasis

NATIONAL PROGRAMME FOR

by the year 2020.

CONTROL OF BLINDNESS (NPCB)

Target is to develop ‘National Onchocerciasis Control

IN INDIA

Programme’ with satisfactory coverage in all the 37

countries where disease is endemic.

India was the first country in the world to launch the

Strategy is to introduce community directed treatment

‘National Programme for Control of Blindness (NPCB)’

with annual doses of Mectizan (ivermectin). The

in the year 1976 as 100 percent centrally sponsored

disease in expected to be brought under control by

programme which incorporated the earlier trachoma

the year 2010, if present efforts in endemic countries

control programme started in the year 1963 and vitamin

are successfully implemented.

A prophylaxis programme launched in 1970.

STRATEGIC PLAN FOR ‘VISION 2020’:

OBJECTIVES

THE RIGHT TO SIGHT IN INDIA

In 1976, the NPCB was launched with following goals:

To provide comprehensive eye care facilities for

It is described under National Programme for Control

primary, secondary and tertiary levels of eye

of Blindness in India (page 451).

health care.

To reduce the prevalence of blindness in

VISION FOR THE FUTURE (VFTF)

population from 1.38% (ICMR 971-74) to 0.31 by

Vision for the future

(VFTF): International

2000 AD.

Ophthalmology Strategic Plan to Preserve and Restore

The programme got a major flip drug 1994-2001

Vision¹¹, launched in Feb 2001, is another global

when World Bank assisted “Cataract Blindness

initiative (in addition to Vision 2020) for prevention

Control Project” was launched to reduce the cataract

of blindness.

back-log in 7 States which were identified to have the

Implementation of this program is being done by

highest prevalence of cataract blindness by WHO-

International Council of Ophthalmology (ICO) by

NPCB survey (1986-89). These, in descending order,

working closely with other international,

are: Uttar Pradesh, Tamil Nadu, Madhya Pradesh,

supranational and national organizations. It is parallel

Maharashtra, Andhra Pradesh, Rajasthan and Orissa.

to and complementary of ‘Vision 2020’. Care is being

However, the latest survey conducted between

taken to avoid duplication.

2001 and 2002 has estimated a prevalence of 1.1% in

Top priorties for action of this programme are:

the general population, indicating just a marginal

reduction in the prevalence of blindness.

Enhancement of ophthalmology residency training

Recently, government of India has adopted ‘Vision

around the world, particularly through definition

2020: Right to Sight’ under National Programme for

of principles, guidelines and curricula.

Control of Blindness. The initiative ‘Vision 2020’ has

Development of model guidelines and

been launched with the objective to eliminate

recommendations for ophthalmic clinical care in

avoidable blindness by the year 2020.

critical disease areas.

Dissemination of sample curricula for training of

PLAN OF ACTION AND ACTIVITIES

medical students and allied health personnel.

The plan of action and activities of ‘National

Advocacy and support for ‘Vision 2020: Right to

Programme for Control of Blindness (NPCB) in India

Sight’, particularly by encouraging national

can be described under three headings:

ophthalmologic societies to support the initiative

Basic programme components,

and become involved.

Programme organization, and

Helping national ophthalmologic societies

Strategic plan for ‘Vision 2020: Right to Sight’ in

develop more effective organizations.

India.

COMMUNITY OPHTHALMOLOGY

449

BASIC PROGRAMME COMPONENTS

the most significant developments in the field of eye

health care over the last few years. A wide range of

The basic components of NPCB since its inception

eye conditions can be treated/prevented at the grass-

includes the following ¹²:

root level by locally-trained primary health workers

Extension of eye care services.

who are the first to make contact with the community.

Establishment of permanent infrastructure.

Peripheral sector for primary eye care at PHC and

Intensification of eye health education.

subcentre levels is being strengthened by:

A. Extension of eye care services

Providing necessary equipment,

It is being done through the state and district mobile

Posting a paramedical ophthalmic assistant, and

units by adopting an ‘eye camp approach’ and by

Organising refresher courses for doctors and

enlisting the participation of voluntary organisations.

other staff of PHC on prevention of blindness.

The following facilities are being provided in remote

By the year

2002,

5033 PHCs had been

areas:

strengthened.

1. Medical and surgical treatment for the prevention

Community ophthalmic practice at primary care

and control of common eye diseases. Eye camp

level is summarized in Table 20.3.

approach is of great help in reducing the back-

2. Establishment of intermediate sector for

log of cataract by mass surgeries. Recent

‘secondary eye care’. Secondary eye care involves

emphasis is on reach-in-approach.

definitive management of common blinding conditions

2. Detection and correction of refractive errors.

such as cataract, glaucoma, trichiasis, entropion and

3. Thorough ocular examination including vision of

ocular trauma.

school children for early detection of eye diseases

The intermediate sector for secondary eye care is

and promoting ocular health.

being strengthened by development of diagnostic

4. Rehabilitation training of visually handicapped.

and treatment facilities at district and subdivisional

5. General survey for prevalence of various eye

levels under the charge of an eye specialist.

diseases.

3. Establishment of central level for ‘tertiary eye

care’. Tertiary eye care services include the

B. Establishment of permanent infrastructure

sophisticated eye care such as retinal detachment

The ultimate goal of NPCB is to establish permanent

surgery, laser treatment for various retinal and other

infrastructure to provide eye care services. It is being

ocular disorders, corneal grafting and other complex

done in three-tier system i.e., peripheral, intermediate

forms of management not available in secondary eye

and central level.

care centres.

1. Establishment of peripheral sector for primary

The central level for tertiary eye care services and

eye care. The concept of primary eye care is one of

development of manpower is being strengthened by

Table 20.3: Community Ophthalmology Practice at Primary Level.

Promotive

Preventive

Curative

Rehabilitative

Nutrition Education

Ocular prophylaxis

Vision

Provision of low

Improved maternal

at birth

screening

vision services

and child nutrition

Vitamin A doses

Treatment for

Community based

Health education

Measles vaccine

vitamin A def.

rehabilitation

Face washing

Perinatal care

Referral for

Counselling of the

Good antenatal care

Avoid medication in

surgery

incurably blind

Safe water

pregnancy

Emergency

Certification of blind

Improved -

Avoid hypoxia at birth

management

by eye surgeon

environmental

Examine neonate’s eyes

Treatment for

Sensitise about

sanitation

Nutrition

trachoma

concessions

supplementation

Treatment for

other common

eye diseases

450

Comprehensive OPHTHALMOLOGY

upgradation of eye departments of state medical

Central level activities include:

colleges and by establishment of regional institutes

l. Procurement of goods (major equipments, bulk

of ophthalmology (RIO).

consumables, vehicles, etc.)

4. Establishment of an apex National Institute of

2. Non-recurring grant-in-aid to NGOs.

Ophthalmology. An apex National Institute of

3. Organizing central level training courses.

Ophthalmology has been established at Dr. Rajendra

4. Information, education and communication (IEC)

Prasad Centre for Ophthalmic Sciences, New Delhi.

activities

(prototype development and mass

This institute has been converted into a centre of

media).

excellence to provide overall leadership, supervision

5. Development of MIS, monitoring and evaluation.

and guidance in technical matters to all services and

6. Procurement of services and consultancy.

technical institutions under the programme.

7. Salaries of additional staff at the central level.

C. Intensification of eye health education

2. State level

Health education is an important long-term measure

The NPCB is implemented through the State

in order to create community awareness of the

Government. A ‘State Programme Cell’ is already in

problem, to motivate the community to accept total

place for which five posts including that of a Joint

eye health care programmes, and to secure community

Director (NPCB) have been created.

participation.

State-level activities include:

Intensification of eye health education is being

l. Execution of civil works for new units.

done through mass communication media (television

2. Repairs and renovation of existing units/

talks, radio talks, films, seminars and books), school

equipments.

teachers, social workers, community leaders, mobile

3. State level training and IEC activities.

ophthalmic units, and existing medical and paramedical

4. Management of State Project Cell.

staff. Main stress is laid on care and hygiene of eyes

5. Salaries for additional staff.

and prevention of avoidable diseases.

Recently, it has been proposed to establish ‘State

Health education about hygiene of vision in school

Blindness Control Society’ (SBCS) in major states for

children is being imparted with regard to good reading

monitoring and implementing the programme at the

posture, proper lighting, avoidance of glare, and a

state level. The SBCS will release grant-in-aid to

proper distance.

District Blindness Control Societies (DBCS) for

various activities.

PROGRAMME ORGANIZATION

3. District level

Various programme activities implemented at central,

state and district levels are as follows:¹³

To organize the programme at district level, ‘District

Blindness Control Societies’ have been established.

1. Central level

District blindness control society

At the central level, programme organization is the

responsibility of the

‘National Programme

The concept of ‘District Blindness Control Society

Management Cell’ located in the office of Director

(DBCS)’ has been introduced, with the primary

General Health Services (DGHS), Department of

purpose to plan, implement and monitor the blindness

Health, Government of India (GOI). To oversee the

control activities comprehensively at the district level

implementation of the programme three national

under overall control and guidance of the ‘National

bodies have been constituted as below:

Programme for Control of Blindness'. This concept

National Blindness Control Board, chaired by

has been implemented after pioneering work by

Secretary Health to GOI.

DANIDA in five pilot districts in India.

National Programme Co-ordination Committee,

Objective of DBCS establishment is to achieve the

chaired by Additional Secretary to GOI.

maximum reduction in avoidable blindness in the

National Technical Advisor Committee, headed

district through optimal utilisation of available

by Director General Health Services, GOI.

resources in the district.

COMMUNITY OPHTHALMOLOGY

451

Need for establishment of DBCS was considered

STRATEGIC PLAN FOR VISION 2020:

because of the following factors:

THE RIGHT TO SIGHT IN INDIA

1. To make control of blindness a part of the

The Government of India has adopted ‘Vision 2020:

Government’s policy of designating the district

Right to Sight’ under ‘National Programme for Control

as the unit for implementing various development

of Blindness’ at a meeting held in Goa on October 10-

programmes.

13, 2001 and constituted a working group. The draft

2. To simplify administrative and financial

plan of action submitted by the ‘Working Group’ to

procedures.

the Ministry of Health and Family Welfare Govt. of

3. To enhance participation of the community and

India in August, 2002 includes following strategies:¹³

the private sector.

A. Strengthening advocacy

Composition of DBCS. Each DBCS will have a

B. Reduction of disease burden

maximum of 20 members, consisting of 10 ex-officio

C. Human resource development, and

and 10 other members with following structure:

D. Eye care infrastructure development

Chairman: Deputy Commissioner/District

Magistrate.

A. Strengthening advocacy

Vice-Chairman: Civil Surgeon/District Health

To strengthen advocacy and generate public

Officer.

awareness various activities are proposed at national,

Member Secretary: District Programme Manager

state, and district level under Vision 2020 initiative in

(DPM) or District Blindness Control Co-ordinator

India. The essence of these activities is:

(DBCC), who is appointed by the Chairman. DPM

Public awareness and information about eye care

will co-ordinate the activities of the programme

and prevention of blindness.

between the government and non-government

Introduction of topics on eye care in school

organizations (NGOs).

curricula.

Members will include District Eye Surgeon, District

Education Officer, President local IMA branch,

Involvement of professional organizations such

President Rotary Club, representatives of various

as All India Ophthalmological Society (AIOS),

NGOs and local voluntary action groups. The ex-

Eye Bank Association of India (EBAI) and Indian

officio members will be the members of the society

Medical Association

(IMA) in the National

as long as they hold the post. The term of other

Programme for Control of Blindness.

members is notified by the Chairman.

To strengthen the functioning of District

Advisor of the society is the State Programme

Blindness Control Society (DBCS).

Manager.

To enhance involvement of NGOs, local

Technical guidance is provided by the Chief

community societies and community leaders.

Ophthalmic Surgeon/Head of the Ophthalmo-logy

To strengthen hospital retrieval programmes for

Department of Medical College.

eye donation through effective grief counselling

Revised strategies adopted for implementation of

by involving volunteers, Forensic Deptt., Police

programme at district level are:

etc.

1. Annual district action plan is to be submitted by

DBCS. Funding will be in two instalments through

B. Reduction of disease burden (disease-specific

GOI/SBCS.

approach)

2. NGO participation made accountable; allotted area

Target diseases identified for intervention under

of operation.

‘Vision 2020’ initiative in India include:

3. Revised guidelines for DBCS

— capping of

Cataract,

expenditure; phasing out contract managers.

Childhood blindness,

4. Emphasis on utilization of existing government

Refractive errors and low vision,

facilities.

Corneal blindness,

5. Gradual shift from camp surgery to institutional

surgery.

Diabetic retinopathy,

6. Development of infrastructure and manpower for

Glaucoma, and

IOL surgery.

Trachoma (focal)

452

Comprehensive OPHTHALMOLOGY

Cataract

disorders, refractive errors, squint, amblyopia and

Cataract continues to be the single largest cause of

corneal diseases:

blindness. According to latest National Survey in

At the time of primary immunization,

India (1999-2001), 62.6% of blindness in 50 +

At school entry, and

population of India was found to be cataract related.

Periodic check up every 3 years for normal and

Objective. To improve the quantity and quality of

every year for those with defects.

cataract surgery.

2. Preventable childhood blindness to be taken

Targets and strategies include:

care of through cost effective measures:

To increase the cataract surgery rate to 4500 per

Prevention of xerophthalmia is of utmost value

million per year by 2005, 5000 by 2010, 5500 by

in preventing childhood blindness (see page

2015 and 6000 by 2020.

436).

To improve the visual outcome of surgery to

Prevention and early treatment of trachoma by

conform to standards set by WHO (i.e., 80% to

active intervention (see page 67 and 447).

have visual outcome 6/18 or >6/18 after surgery).

Refractive errors to be corrected at primary eye

IOL surgery for >80% by the year 2005 and for

care centres.

all by the year 2010.

Childhood glaucomas to be treated promptly.

YAG capsulotomy services at all district hospitals

Harmful traditional practics need to be avoided.

by 2010.

Prevention of ROP by proper screening and

monitoring use of oxygen in premature new

Grant-in aid for cataract surgery may continue to be

borns.

released through DBCS.

3. Curable childhood blindness due to cataract,

Childhood blindness

ROP, corneal opacity and other causes to be

Childhood blindness is an important public health

taken care of by the experts at secondary and

problem in developing countries due to its social and

tertiary level eye care services.

economic implications. Though prevalence of

Targets include:

childhood blindness is low as compared to blindness

Establishment of Paediatric Ophthalmology

in the aged, it assumes significance due to large

units. In India, 50 Pediatric Ophthalmology units

number of disability years of every child remaining

are to be established by

2010 for effective

blind.

management of childhood diseases.

Extent and causes of problem. Prevalence of

Establishment of refraction services and low

childhood blindness in India has been projected to

vision centers (see below ).

be 0.8/1000 children by using the correlation between

Refractive errors and low vision

under five mortality rate and prevalence. Currently,

Aim and stratigies are same as described for ‘Vision

there are an estimated 270,000 blind children in India.

2020’ Global initiative (see page 447)

Common causes of childhood blindness are vitamin

Targets. To combat refractive error and low vision

A deficiency, measles, conjunctivitis, ophthalmia

following targets have been set in India:

neonatorum, injuries, congenital cataract, retinopathy

Refraction services to be available in all primary

of prematurity (ROP), and childhood glaucoma.

health centres by 2010. Availability of low-cost,

Refractive errors are the commonest cause of visual

good quality spectacles for children to be insured.

impairment in children.

Low vision service centres are to be established

Aim is to eliminate avoidable causes of childhood

at 150 tertiary level eye care institutions. 50 such

blindness by the year 2020.

centres are to be developed by 2010, another 50

Strategies and activities under Vision 2020: Right to

by 2015 and the final 50 by 2020.

Sight initiative in India include:

1. Detection of eye disorders. Following schedule

Glaucoma

of ophthalmic examination of children is

As per the ‘National Survey on Blindness’ (1999-2001,

recommended to identify early childhood

Govt. of India Report 2002)⁹ glaucoma is responsible

COMMUNITY OPHTHALMOLOGY

453

for 5.8% cases of blindness in 50+ population.

ophthalmology and is a great challenge to the medical

Effective intervention for prevention of glaucoma

profession in general and ophthalmolgists in

resultant blindness is quite difficult. Failure of early

particular. This challenge can be faced boldly by the

detection of the disease poses a management problem

combined efforts of the public and the government;

towards controlling glaucomatous blindness.

especially the education department, school teachers,

Population based screening of glaucoma is not

general medical practitioners and ophthalmologists.

recommended as a strategy in developing countries.

Objectives regarding corneal blindness under ‘Vision

Following measures are recommended for

2020’ in India are:

opportunistic glaucoma screening (case detection)

To reduce prevalence of preventable and curable

by tonometry and fundus examination:

corneal blindness.

Opportunisitic screening at eye care institutions

To identify the infants at risk in cooperation with

should be done in all persons above the age of

RCH programme.

35 years, those with diabetes mellitus, and those

Strategies for control of corneal blindness include:

with family history of glaucoma.

Eye infections. Health education and improvement

Community based referral by multi-purpose

in personal hygiene will reduce the incidence of

workers of all persons with dimunition of vision,

conjunctivitis, corneal ulcer and other eye

coloured haloes, rapid change of glasses, ocular

infections. Early treatment of eye infections will

pain and family history of glaucoma.

prevent corneal blindness.

Opportunistic screening at eye camps in all

Eye injuries. Education of people regarding

patients above the age of 35 years.

avoidance of ocular trauma like cracker blast,

industrial accidents, road accidents and other

Diabetic retinopathy

trauma, thereby reducing irreversible corneal

Diabetic retinopathy (DR) is emerging as an important

blindness. Ocular trauma cases should be

cause out of 4.7% cases of blindness due to posterior

immediately referred to specialists for effective

segment disorders in 50+ population (National Survey

management. Facilities for administrating general

1999-2001)⁹. To prevent visual loss occurring from

anaesthesia for ocular trauma patients at

diabetic retinopathy a periodic follow-up (see page

secondary eye care level.

262) is very important for timely intervention.

Trachoma Blindness. In India the corneal

Following recommendations are made:

blindness due to trachoma (0.39% WHO-NPCB,

Awareness generation by health workers.

1986-88) is on the decline when compared with

All known diabetics to be examined and referred

previous figures (20% ICMR 1975). However, In

to Eye Surgeon by the Ophthalmic Assistant.

isolated pockets

(focal) blindness related to

Confirmation by fundus fluorescein angiography

trachoma continues to be important. For

(FFA) and laser treatment of diabetic retinopathy

prevention of trachoma blindness see page 67

at tertiary level.

and 447.

The strategy must be to bring down the medical

Prevention of Xerophthalmia will make a strong

management of DR at the secondary level.

dent in the number of corneal blinds. The three

major known intervention strategies for the

Corneal blindness

prevention and control of vitamin A deficiency

Background. A significant number of cases of visual

are described on page 436.

impairment and gross degree of loss of vision occur

A total ban should be placed on the ophthalmic

due to diseases of the cornea. There are about 1

practice by quacks and sale of harmful eye

million corneal blinds in India. Majority of these

medicines especially various ‘surmas’.

persons are affected in the first and second decade

The eyes of industrial workers and agriculturists

of life. The major causes of this blindness are corneal

should be given protection by goggles and eye

ulcers due to infections, trachoma, ocular injuries and

shades.

keratomalacia caused by nutritional deficiencies.

7. Corneal blindness and keratoplasty. There is a

Thus, corneal blindness is one of the outstanding

need of around

1 lakh corneas per year for

problems in the field of preventive and community

transplantation to clear the backlog of corneal

454

Comprehensive OPHTHALMOLOGY

blindness. Currently we are collecting around

25000 eyes per year. As keratoplasty operation

can restore vision in a significant number of

corneal blinds, an intensive publicity and

cooperation of government and non-government

agencies is needed to enhance the voluntary eye

donations. More eye banks should be established

and more ophthalmic surgeons should be trained

for corneal grafting. Under Vision 2020: Indian

initiative emphasis is on hospital retrieval system

to get better donor material.

C. Human resource development

For ‘Vision 2020’ initiative in India, the human resource

needs identified to combat blindness by 2020 are

depicted in Table 20.4.

Mid-Level Ophthalmic Personnel (MLOP). The term

MLOP has been introduced to include all categories

of paramedics who work full time in eye care. Broadly

Fig. 20.1. The infrastructure pyramid, based on the

two streams of such personnels are envisaged:

recommendations of WHO.

1. Hospital-based MLOP. These include ophthalmic

nurses, ophthalmic technicians, optometrists, and

service centres at secondary level — each with

orthoptists etc.

two ophthalmologists and 8 paramedics (Hospital

2. Community-based MLOP include those with out-

based MLOP), covering a population of 500000.

reach/field functions such as primary eye care

One eye care manager will be required at each

workers and ophthalmic assistants.

service centre.

Training Centres. There is a need to develop 200

D. Eye care infrastructure development

‘Training Centres’ for the training of

Based on the recommendations of WHO, there is need

Ophthalmologists. Each tertiary level training

to develop the infrastructure pyramid which includes

centre will cater to a population of 5 million.

(Fig. 20.1):

Centre of Excellence (COE). There is need to

1. Primary level Vision Centres. There is a need to

develop 20 COE with well developed all sub

develop

20000 vision centres, each with one

Ophthalmic Assistant or equivalent (Community

specialities of Ophthalmology. Each advanced

based MLOP) covering a population of 50000.

tertiary level center of excellence will cater to a

2. Service Centres. There is need to develop 2000

population of 50 millions.

Table 20.4: Human resource needs for the country to combat blindness by 2020.

Sr. No. Category

Current

Required by the year

number

2005

2010

2015

2020

Ophthalmic surgeons

12000

15000

18000

21000

25000

Ophthalmic assistants

6000

10000

15000

20000

25000

(community)

Ophthalmic paramedics

18000

30000

36000

42000

48000

(Hospital)

Eye-care managers

200

500

1000

1500

2000

Community eye health

100

150

200

specialists

COMMUNITY OPHTHALMOLOGY

455

ROLE OF EYE CAMPS IN PREVENTION OF

5. Other activities. These include arrangement for

BLINDNESS

medicines and food for the patients, stay

arrangements for the medical team and mobilization

Objectives

of volunteers and social workers, for rendering

Eye camp approach for prevention of blindness still

assistance to the camp team.

plays a vital role in the developing countries where

B. Intensive phase. Eye camps should last 7 days out

infrastructure is not fully established. It is particularly

of which 2-3 days should be set apart for intensive

more relevant keeping in view the fact that still 62.6%

phase, during which following activities need to be

of blindness in India is due to cataract which can be

performed:

very well cured in eye camps.

The medical team comprising at least one resident

doctor, 2 nurses, 2 operation theatre assistants

Organization of an eye camp

and 2 paramedical personnel should reach the

Presently two types of eye camps are held:

camp site an evening before the scheduled

Comprehensive eye care camps with ‘Reach-out

commencement of the camp. They should set up

Approach’, and

the OPD, ward and operation theatre. The OT

Screening eye camps (Reach-in-Approach with

room should be fumigated with formalin vapours

comprehensive eye care).

and kept closed overnight.

As mentioned earlier the recent emphasis is on the

Patients are provided comprehensive eye care

‘Reach-in-Approach’.

services including refraction. Those requiring

surgical intervention for cataract or other diseases

I. Comprehensive eye - care camps with ‘Reach-

are admitted in the ward. For performing

Out-Approach’

ophthalmic surgery, following guidelines laid

down by Govt. of India should be adhered to:

A. Preparatory phase is most important for the

At least one anaesthetist with arrangements to

successful organization of an eye camp. Activities

meet common emergencies should be available.

during this phase are:

At least one, preferably two, operating

1. Finalization of organizers and medical team.

surgeons should be there and each surgeon

Presently, most of the eye camps are planned and

should not perform more than thirty operations

co-ordinated by the DBCS. Usually, the organizers

in a day.

are voluntary organizations of repute. The medical

Presently extracapsular cataract extraction (by

team is either from district mobile ophthalmic

any technique) with posterior chamber

units or charitable hospitals or state mobile

intraocular lens implantation is the

ophthalmic units.

recommended method.

2. Permission to hold eye camp. Permission is sought

Ideally the number of operations performed

by the organizers from the Chief Medical Officer/

per day should not exceed 50 and in a camp

Civil Surgeon of the district.

should not exceed 200 to maintain quality and

3. Selection of the camp site. The eye camps should

safety of sterilization, surgery and post-

operative care.

preferably be held at CHC/PHC/charitable

Both the eyes should never be operated at

hospitals/ civil hospital, so that available operation

one go.

theatre facilities can be used.

Cases with poor surgical risk such as severe

4. Publicity and mobilisation of community

diabetics, severe hypertensives and those

resources. These are most important aspects for

having cardiac problems should not be

the success of an eye camp. Publicity should

operated in camps. The cases associated with

start at least a fortnight prior to the actual camp

problems like these should be referred to the

dates. Method of publicity should include public

base hospitals.

announcements, radio broadcast and display of

Along with curative and preventive services, eye

banners and posters at prominent places like

health education is also carried out

bus-stands, railway stations, schools etc.

simultaneously.

456

Comprehensive OPHTHALMOLOGY

C. Consolidation phase of 4-5 days follows the

Functions of an eye bank include:

intensive phase with following activities:

1. Promotion of eye donation by increasing

Care of operated and other admitted patients.

awareness about eye donation to the general

Out-patient’s care including refraction.

public.

Community eye health and morbidity surveys

2. Registration of the pledger for eye donation.

with greater emphasis on school children.

3. Collection of the donated eyes from the deceased.

D. Culmination and retrieval phase. On the morning

4. Receiving and processing the donor eyes.

of last day, each patient is very carefully examined

5. Preservation of the tissue for short, intermediate,

and discharged after proper guidance. After this, the

long or very long term.

men and material resources are packed up and

6. Distribution of the donor tissues to the corneal

transported back to the base hospital.

surgeons.

7. Research activities for improvement of the

E. Follow-up phase. One ophthalmic surgeon with

preservation methodology, corneal substitute and

the help of one ophthalmic assistant, one staff nurse

and paramedical personnel conducts the follow-up

utilisation of the other components of eye.

examination after 4-6 weeks of closing of the camp.

Eye bank personnel include:

During this, phase, glasses are prescribed after

Eye bank incharge. He should be a qualified

removing the sutures and the patients are given

ophthalmologist to evaluate, process and

further necessary advice.

distribute the donor tissue.

Eye bank technician. The duties of a trained eye

II. Screening eye camps (Reach-in-Approach)

bank technician are:

According to revised strategies, emphasis is to shift

To keep the eye collection kits ready.

from ‘Reach-out to the ‘Reach-in-Approach’. In

To assist in enucleation of donor eyes.

‘Reach-in-Approach’, the ‘screening camps’ are held

To record data pertaining to donor material

in rural and remote areas where eye-care facilities are

and waiting list of patients.

not available. Patients are provided comprehensive

To process and treat the donor eyes with

eye care services including refraction. Patients in need

antibiotics.

of cataract surgery are then transported to the nearest

To assist in corneal preservation and storage.

well-equipped hospitals (Base hospital approach).

To maintain asepsis in the eye bank.

Emphasis is on extracapsular cataract extraction with

Clerk-cum-storekeeper. The duties are:

posterior chamber IOL implantation for better quality

To maintain meticulous records.

of vision. Many eye surgeons are now performing

To coordinate with other eye banks.

sutureless small incision cataract surgery (SICS) with

To deal with other eye banks and exert with

posterior chamber intraocular lens implantation. The

trained surgeons are even performing the cataract

efficiency regarding donor’s correspondence.

surgery by latest technique i.e., phacoemulsification

To distribute cornea to eye surgeons/eye

in eye camps.

banks.

Medical social worker or public relation officer

Documentation, monitoring and evaluation

is required:

A complete and meticulous record of the patients

To supply publicity material to common public

treated in the eye camp along with the post-operative

To promote voluntary eye donation.

complications noted and managed should be kept.

He may be a voluntary or paid worker.

Each eye camp should be monitored by the competent

Driver-cum-projectionist is required:

authorities and evaluated in terms of various activities

To maintain vehicle of the eye bank.

assigned to such camps and the results obtained.

To screen films of eye donation promotion in

EYE BANKING

the community.

Eye collection centres. These are the peripheral

Eye bank is an organization which deals with the

satellites of an eye bank for better functioning. One

collection, storage and distribution of cornea for the

collection centre is viably located at an urban area

purpose of corneal grafting, research and supply of

the eye tissue for other ophthalmic purposes.

with a population of more than 200,000. About 4-5

COMMUNITY OPHTHALMOLOGY

457

collection centres are attached with each eye bank.

REHABILITATION OF THE BLIND

Functions of eye collection centre are:

Rehabilitation of the blind is as important as the

Local publicity for eye donation.

prevention and control of blindness; spiritually

Registration of voluntary donors.

speaking even more. A blind person needs the

Arrangement for collection of eyes after death.

following types of rehabilitation:

Initial processing, packing and transportation of

1. Medical rehabilitation. By low vision aids (LVA)

collected eyes to the attached eye bank.

many visually handicapped can have a useful

Personnel needed for eye collection centre are:

vision.

Ophthalmic technician trained in eye bank.

2. Training and psychosocial rehabilitation. It is

Local honorary workers/voluntary agencies like

the most important aspect. First of all the blinds

Lions club, Rotary club etc. to boost the eye

should be assured and made to feel that they are

donation campaign.

equally useful and not inferior to the sighted

Services of honorary ophthalmic surgeon or

persons. Their training should include:

medical officer trained in enucleation available on

Mobility training with the help of a stick.

call.

Training in daily living skills such as bathing

Legal aspect. The collection and use of donated eyes

washing, putting on clothes, shaving, cooking

come under the perview of ‘The Transplantation of

and other household work.

Human Organs Act, 1994’.

3. Educational rehabilitation. It includes education

avenues in ‘Blind Schools’ with the facility of

Facts about eye donation

Braille system of education.

Almost anyone at any age can pledge to donate

4. Vocational rehabilitation. It will help them to

eyes after death; all that is needed is a clear

earn their livelihood and live as useful citizens.

healthy cornea.

Blinds can be trained in making handicrafts,

The eyes have to be removed within six hours of

canning, book binding, candle and chalk making,

death.

cottage industries and as telephone operators.

Eye donation gives sight to two blind persons as

To conclude, it should never be forgotten that, one

one eye is transplanted to one blind person.

of the basic human rights is the right to see. The

The eyes can be pleged to an eye bank and can

strategicians MUST ensure that:

be actually donated to any nearest eye bank at

No citizen goes blind needlessly due to

the time of death.

preventable causes.

The donated eyes are never bought or sold.

All avenues are exhausted to restore the best

Eye donation is never refused.

possible vision to curable blinds.

The eyes cannot be removed from a living human

Blinds not amenable to curable measures receive

being inspite of his/her consent and wish.

comprehensive rehabilitation.

458

Comprehensive OPHTHALMOLOGY

REFERENCES

1. WHO (1966). Epi and Vital Statis. Rep., 19: 437.

General Health Services, Ministry of Health and

Family Welfare, New Delhi.

2. The Prevention of Blindness. Report of a WHO Study

Group. Geneva, World Health Organization, 1973

9. Govt of India, National Survey on Blindness: 1999-

(WHO Technical Report Series, No. 518).

2001, Report 2002.

3. WHO (1979). WHO Chronicle 33: 275.

10. Strategic plan for Vision 2020: The Right to Sight

4. WHO

(1977). International Classification of

WHO Report. SEA-Ophthal 177, 2000

Diseases. Vol. 1, p. 242.

11. Vision for the Future, International ophthalmology

5. WHO (1997), The World Health Report

1997,

strategic plan to preserve and Restore Vision, 2001.

Conquering suffering, Enriching humanity, Report

12. Govt. of India (1992), Present Status of National

of the Director-General WHO.

Programme

for

Control

Blindness,

6. Thylefors B et al. Global Data on Blindness. Bull.

Ophthalmology Section, DGHS, New Delhi, 1992.

WHO 1995; 73: (1) 115-121.

13. Strategic plan for Vision 2020: The Right to sight

7. Indian Council of Medical Research : Collaborative

initiative in India, National Programme for control

study on Blindness (1971-74).

of blindness, Director General of Health Services,

8. Report of National Workshop

(1989). National

Ministry of Health and Family Welfare Govt. of

Programme for Control of Blindness. Director

India.

INTRODUCTION TO

PRACTICAL OPHTHALMOLOGY

Medical graduates have to apply the knowledge

3. OPHTHALMIC INSTRUMENTS AND

gained during their five and a half years of exhaustive

OPERATIVE OPHTHALMOLOGY

study course, for the management and care of a patient

The aim of this part of practical examination is to

in one or the other way. Therefore, it is imperative for

assess the students for their exposure and

them to learn and practise the art of medicine.

acquaintance with functioning of the ophthalmic

Consequently the practical examinations have been

operation theatre. Students should be able to identify

given equal importance to that of theory examinations

and tell the utility of common eye instruments. They

during the entire study course. Practical training is

should be able to describe the techniques of local

thus supplementary and complementary to the lecture

ocular anaesthesia and to enumerate the main steps

course.

of a few common eye operations. Students are also

Practical examinations in ophthalmology are

conducted with the main aims to evaluate a student

supposed to be familiar with the commonly used

for his or her capability to identify and diagnose

ophthalmic equipment including uses of cryo and

common eye diseases to provide primary eye care

lasers in ophthalmology. Subject matter relevant to

and to timely refer the patients needing secondary

this part of practical examinations is described in

and tertiary level services to the eye hospitals as per

Chapter 24 of this book.

the indications.

To assess the students for the above-mentioned

4. SPOTTING

capabilities, the practical examinations are conducted

In some centres, spotting also forms a part of practical

under the following heads:

examinations. This allows an overall objective

evaluation of the candidate. Commonly employed

1. CLINICAL CASE PRESENTATION

spots in ophthalmology practical examinations

Under this section, students are assessed for their

include : a typical photograph of any common eye

knowledge and art of a meticulous history taking,

disorder, an instrument, photograph of any

methods of examination, diagnostic skills and plan of

ophthalmic equipment, a darkroom appliance, a

management of an ophthalmic patient. For this

purpose, the students are supposed to work up a

fundus photograph or a visual field chart.

long case and/or 2 to 3 short cases with common eye

disorders. The approach to clinical work of an

5. VIVA QUESTIONS

ophthalmic patient is given in Chapter 21 of the book.

Viva questions form an integral and important part of

The clinical case presentation along with the related

each section of the practical examination, viz. clinical

viva questions have been described in Chapter 22 of

case presentation, darkroom examination and

this book.

description of ophthalmic instruments. Therefore,

relevant questions have been described in the

2. DARKROOM EXAMINATIONS

concerned sections.

Students are evaluated for their knowledge of basic

The main aim of the examiner during the session

principles, clinical applications, procedures and the

of viva questions is to assess the student's overall

equipment required for the commonly performed

familiarity with common disorders of the eye, their

darkroom procedures. These procedures along with

management and important recent developments in

relevant viva questions have been described in

Chapter 23 of this book.

the field of ophthalmic practice.

CHAPTER

ogy

21^Opihthallmo

HISTORY AND EXAMINATION

Electroretinography and electrooculography

History

Visually evoked response (VER)

General physical and systemic

Ultrasonography

examination

SPECIAL EVALUATION SCHEMES*

Ocular examination

Evaluation of a case of glaucoma

- Testing of visual acuity

Examination of a case of squint

- External ocular examination

- Fundus examination

Evaluation of a case of epiphora

Evaluation of a case of dry eye

TECHNIQUES OF OCULAR EXAMINA-

Evaluation of a case of proptosis

TION AND DIAGNOSTIC TESTS

Determination of refractive errors

Oblique illumination

Tonometry

LABORATORY INVESTIGATIONS*

Techniques of fundus examination

ROENTGEN EXAMINATIONS*

Perimetry

PATHOLOGICAL STUDIES*

Fundus fluorescein angiography

* Discussed in the related chapters

patient is also useful for noting down and ruling out

HISTORY AND EXAMINATION

the particular diseases pertaining to different age

groups and a particular sex.

HISTORY

Occupation. An information about patient’s

The importance of painstaking meticulous history

occupation is helpful since ophthalmic manifestations

cannot be overemphasized. The complete history-

due to occupational hazards are well known, e.g.:

taking should be structured as:

Ocular injuries and trauma due to foreign bodies

Demographic data

have typical pattern in factory workers, lathe

Chief presenting complaints

workers, farmers and sport persons.

History of present illness

Computer vision syndrome is emerging as a

History of past illness

significant ocular health problem in computer

Family history

professionals.

Heat cataract is known in glass factory workers.

Demographic data

Photophthalmitis is known in welders not taking

Demographic data should include patient’s name, age,

adequate protective measures.

sex, occupation and religion.

In addition, information about the patient’s

Name and address. Name and address are primarily

occupation is useful in providing ocular health

required for patient’s identification. It also proves

education and patient’s visual rehabilitation.

useful for demographic research.

Religion. Recording the religion of the patient may

Age and sex. In addition to the utility in patient’s

be helpful in ascertaining the diseases which are more

identification, knowledge of the age and sex of the

common in a particular community. It also helps in

462

Comprehensive OPHTHALMOLOGY

knowing the aptitude and practices prevalent in

History of any systemic disease in the past such

different communities for various common eye

as tuberculosis, syphilis, leprosy may sometimes

problems.

explain the occurrence of present disease.

History of drug intake is also important.

Chief presenting complaints

Family history

Chief presenting complaints of the patients should

Efforts should be made to establish familial

always be recorded in a chronological order with their

predisposition of inheritable ocular disorders like

duration.

congenital cataract, ptosis, squint, corneal

The common presenting ocular complaints are:

dystrophies, glaucoma and refractive error.

Defective vision

Watering and/or discharge from the eyes

Common ocular symptoms and their causes

Redness

1. Defective vision. It is the commonest ocular

Asthenopic symptoms

symptom. Enquiry should reveal its onset (sudden or

Photophobia

gradual), duration, whether it is painless or painful,

Burning/itching/foreign body sensation

whether it is more during the day, night or constant,

and so on. Important causes of defective vision can

Pain (eyeache and/or headache)

be grouped as under:

Deviation of the eye

Diplopia

Sudden painless loss of vision

Black spots in front of eyes

Central retinal artery occlusion

Coloured halos

Massive vitreous haemorrhage

Distorted vision

Retinal detachment involving macular area

Ischacmic central retinal vein occlusion

History of present illness

Sudden painless onset of defective vision

The patients should be encouraged to narrate their

Central serous retinopathy

complaints in detail and the examiner should be a

Optic neuritis

patient listener. While history taking, the examiner

Methyl alcohol amblyopia

should try to make a note of the following points

Non-ischacmic central retinal vein occlusion

about each complaint:

Sudden painful loss of vision

Mode of onset with duration

Acute congestive glaucoma

Severity

Acute iridocyclitis

Progression

Chemical injuries to the eyeball

Accompaniment of each symptom

Mechanical injuries to the eyeball

History of past illness

Gradual painless defective vision

A probe into history of past illness should be made

Progressive pterygium involving pupillary area

to know:

Corneal degenerations

History of similar ocular complaint in the past. It

Corneal dystrophies

is specially important in recurrent conditions such

Developmental cataract

as herpes simplex keratitis, uveitis and recurrent

Senile cataract

corneal erosions.

Optic atrophy

History of similar complaints in other eye is

Chorioretinal degenerations

important in bilateral conditions such as uveitis,

Age-related macular degeneration

senile cataract and retinal detachment.

Diabetic retinopathy

History of trauma to eye in the past may explain

Refractive errors

occurrence of lesions such as delayed rosette

Gradual painful defective vision

cataract and retinal detachment.

Chronic iridocyclitis

It is important to know about history of any

Corneal ulceration

ocular surgery in the past.

Chronic simple glaucoma

CLINICAL METHODS IN OPHTHALMOLOGY

463

Transient loss of vision (Amaurosis fugax)

Distorted vision. Distorted vision is a feature of

macular lesions e.g., central chorioretinitis. It may be

Carotid artery disease

in the form of:

Papilloedema

Micropsia (small size of objects),

Giant cell arteritis

Macropsia (large size of objects),

Migraine

Metamorphopsia (distorted shape of objects).

Raynaud’s disease

Severe hypertension

Coloured halos. Patient may perceive coloured halos

Prodromal symptom of CRAO

around the light. It is a feature of:

Acute congestive glaucoma

Night blindness (Nyctalopia )

Early stages of cataract

Vitamin A deficiency

Mucopurulent conjunctivitis

Retinitis pigmentosa and other tapetoretinal

Diplopia, i.e., perceiving double images of an object

degenerations

is a very annoying symptom. It should be ascertained

Congenital night blindness

whether it occurs even when the normal eye is closed

Pathological myopia

(uniocular diplopia) or only when both eyes are open

Peripheral cortical cataract

(binocular diplopia). Common causes of diplopia are:

Day blindness (Hamarlopia)

Uniocular diplopia

Central nuclear or polar cataracts

Subluxated lens

Central corneal opacity

Double pupil

Central vitreous opacity

Incipient cataract

Congenital deficiency of cones (rarely)

Keratoconus

Diminution of vision for near only

Eccentric IOL

Presbyopia

Binocular diplopia

Cycloplegia

Paralytic squint

Internal or total ophthalmoplegia

Myasthenia gravis

Insufficiency of accommodation

Diabetes mellitus

2. Other visual symptoms. Visual symptoms other

Thyroid disorders

than the defective vision are as follows:

Blow-out fracture of floor of the orbit

Black spots or floaters in front of the eyes may appear

Anisometropic glasses (e.g., uniocular aphakic

singly or in clusters. They move with the movement

glasses)

of the eyes and become more apparent when viewed

After squint correction in the presence of

against a clear surface e.g., the sky. Common causes

abnormal retinal correspondence

(paradoxical

of black floaters are:

diplopia).

Vitreous haemorrhage

3. Watering from the eyes. Watering from the eyes is

Vitreous degeneration. e.g.,

another common ocular symptom. Its causes can be

- senile vitreous degeneration

grouped as follows:

- vitreous degeneration in pathological myopia

Excessive lacrimation, i.e., excessive formation of

Exudates in vitreous

tears occurs in multiple conditions (see page 367).

Lenticular opacity

Epiphora, i.e., watering from the eyes due to blockage

Flashes of light in front of the eyes (photopsia). Occur

in the flow of normally formed tears somewhere in the

due to traction on retina in following conditions:

lacrimal drainage system (see page 367).

Posterior vitreous detachment

4. Discharge from the eyes. When a patient complains

Prodromal symptom of retinal detachment

of a discharge from the eyes, it should be ascertained

Vitreous traction bands

whether it is mucoid, mucopurulent, purulent,

Sudden appearance of flashes with floaters is a

serosanguinous or ropy. Discharge from the eyes is a

sign of a retinal tear

feature of conjunctivitis, corneal ulcer, stye, burst

Retinitis

orbital abscess, and dacryocystitis.

464

Comprehensive OPHTHALMOLOGY

5. Itching, burning and foreign body sensation in

establishing the aetiological diagnosis, e.g.,

the eyes. These are very common ocular symptoms.

ankylosing spondylitis may be associated with

Their causes are:

uveitis. Further, it is essential to treat associated

Chronic simple conjunctivitis

diseases like bronchial asthma, hypertension,

Dry eye

diabetes and urinary tract problems before taking up

Trachoma and other conjunctival inflammations

the patient for cataract surgery.

Trichiasis and entropion

OCULAR EXAMINATION

6. Redness of the eyes. It is a common presenting

symptom in many conditions such as conjunctivitis,

Testing of visual acuity

keratitis, iridocyclitis and acute glaucomas.

External ocular examination

Fundus examination

7. Ocular pain. Pain in and around the eyes should

be probed for its onset, severity, and associated

I. TESTING OF VISUAL ACUITY

symptoms. It is a feature of ocular inflammations and

Visual acuity should be tested in all cases, as it may

acute glaucoma. Ocular pain may also occur as

be affected in numerous ocular disorders. In real sense

referred pain from the inflammation of surrounding

acuity of vision is a retinal function (to be more

structures such as sinusitis, dental caries and

precise of the macular area) concerned with the

abscess.

appreciation of form sense.

8. Asthenopic symptoms. Asthenopia refers to mild

Distant and near visual acuity should be tested

eyeache, headache and tiredness of the eyes which

separately.

are aggravated by near work. Asthenopia is a feature

of extraocular muscle imbalance and uncorrected mild

The distant visual acuity

refractive errors especially astigmatism.

Snellen’s test types. The distant central visual acuity

9. Other ocular symptoms are as follows:

is usually tested by Snellen’s test types. The fact

Deviation of the eyeball (squint)

that two distant points can be visible as separate

Protrusion of the eyeball (proptosis)

only when they subtend an angle of 1 minute at the

Drooping of the upper lid (ptosis)

nodal point of the eye, forms the basis of Snellen’s

Retraction of the upper lid

test-types. It consists of a series of black capital letters

Sagging down of the lower lids (ectropion)

on a white board, arranged in lines, each progressively

Swelling on the lids (e.g., chalazion and tumours)

diminishing in size. The lines comprising the letters

(These specific symptoms have been discussed

have such a breadth that they will subtend an angle

in the concerned chapter).

of 1 min at the nodal point. Each letter of the chart is

so designed that it fits in a square, the sides of which

GENERAL PHYSICAL AND

are five times the breadth of the constituent lines.

SYSTEMIC EXAMINATION

Thus, at the given distance, each letter subtends an

General physical and systemic examination should

angle of 5 min at the nodal point of the eye (Fig. 21.1).

be carried out in each case. Sometimes it may help in

The letters of the top line of Snellen’s chart (Fig. 21.2)

Fig. 21.1. Principle of Snellen’s test types.

CLINICAL METHODS IN OPHTHALMOLOGY

465

Similarly, depending upon the smallest line which the

patient can read from the distance of 6 m, his vision is

recorded as 6/9, 6/12, 6/18, 6/24, 6/36 and 6/60,

respectively. If he cannot see the top line from 6 m, he

is asked to slowly walk towards the chart till he can

read the top line. Depending upon the distance at

which he can read the top line, his vision is recorded

as 5/60, 4/60, 3/60, 2/60 and 1/60, respectively.

If the patient is unable to read the top line even

from 1 m, he is asked to count fingers (CF) of the

examiner. His vision is recorded as CF-3’, CF-2’,

CF-1’ or CF close to face, depending upon the distance

at which the patient is able to count fingers. When

the patient fails to count fingers, the examiner moves

his hand close to the patient’s face. If he can

appreciate the hand movements (HM), visual acuity

is recorded as HM +ve. When the patient cannot

distinguish the hand movements, the examiner notes

whether the patient can perceive light (PL) or not. If

yes, vision is recorded as PL +ve and if not it is

recorded as PL -ve.

Other tests which are based on the same principle

as Snellen’s test types are as follows:

(a) Simple picture chart: used for children

(b) Landolt’s C-chart: used for illiterate patients

Visual acuity equivalents in some common notations

are depicted in Table 21.1

Fig. 21.2. Snellen’s test types.

Table 21.1. Visual acuity equivalents in some common

notations

should be read clearly at a distance of 60 m. Similarly,

Decimal

Snellen

Angle table

the letters in the subsequent lines should be read

resolution

6-m table

20-foot

system

table

from a distance of 36, 24, 18, 12, 9, 6, 5 and 4m,

respectively.

1.0

6/6

20/20

1 . 0

Procedure of testing. For testing distant visual acuity,

0.8

5/6

20/25

1 . 3

0.7

6/9

20/30

1 . 4

the patient is seated at a distance of 6m from the

0.6

5/9

15/25

1 . 6

Snellen’s chart, so that the rays of light are practically

0.5

6/12

20/40

2 . 0

parallel and the patient exerts minimal accommodation.

0.4

5/12

20/50

2 . 5

The chart should be properly illuminated (not less

0.3

6/18

20/70

3 . 3

than 20 ft candles). The patient is asked to read the

0.1

6/60

20/200

10 .0

chart with each eye separately and the visual acuity

is recorded as a fraction, the numerator being the

Visual acuity for near

distance of the patient from the letters, and the

Near vision is tested by asking the patient to read the

denominator being the smallest letters accurately read.

near vision chart (Fig. 21.3), kept at a distance of 35

When the patient is able to read up to 6 m line, the

cm in good illumination, with each eye separately. In

visual acuity is recorded as 6/6, which is normal.

near vision charts, a series of different sizes of printer

466

Comprehensive OPHTHALMOLOGY

type are arranged in increasing order and marked

J. 1 (Sn. 0.5)

50 cm.

accordingly. Commonly used near vision charts are

As she shoke Moses came slowly on foot, and aweating under the deal box which

he had strapt round his shoulders like a pediar “Welcome, welcome, Moses! well,

as follows:

my boy, what have you brought us from the fair?—“I have brought

1. Jaeger’s chart. In this chart, prints are marked

from 1 to 7 and accordingly patient’s acuity is

J. 2 (Sn. 0.6)

60 cm.

labelled as J1 to J7 depending upon the print he

five shillings and twopence is no bad day’s work. come, let us have it

can read.

then.”—“I have brought back no money,” cried Moses again. “I have laid

2. Roman test types. According to this chart, the

it all out in a bargain and here it is, “pulling out a bundle from his

near vision is recorded as N5, N8, N10, N12 and

N18 (Printer’s point system) (Fig. 21.3).

J. 4 (Sn. 0.8)

80 cm.

3. Snellen’s near vision test types.

mother,” cried the boy, “why won’t you listen to reason. I had

them a dead bargain, or I should not have brought them. The

II. EXTERNAL OCULAR EXAMINATION

silver rims alone will sell for double the money”—“A fig for

External ocular examination should be carried out as

follows:

J. 6 (Sn. 1)

1 m.

A. Inspection in diffuse light should be performed

the rims, for they are not worth sixpence; for I perceive

first of all for a preliminary examination of the eyeballs

they are only copper varnished over.”—“What! cried

and related structures viz. lids, eyebrows, face and

my wife,” not silver! the rims not silver?”—“No,”

head.

B. Focal (oblique) illumination examination should

J. 8 (Sn. 1.25)

1.25 m.

be carried out for a detailed examination under

with copper rims and shagreen cases? A murrain

magnification. It can be accomplished using a

take such trumpery! The blockhead has been

magnifying loupe (uniocular or binocular) and a

imposed upon, and should have know his

focussing torch light or preferably a slit-lamp.

C. Special examination is required for measuring

intraocular pressure (tonometry) and for examining

J. 10 (Sn. 1.5)

1.5 m.

angle of the anterior chamber (gonioscopy).

the idiot!” returned she, “to bring me such

Scheme of external ocular examination is described

stuff: if I had them I would throw them in

here. For details of the examination techniques see

the fire.”—“There again you are wrong, my

page 479. Scheme of examination includes the

structure to be examined and the signs to be looked

for. Further, the important causes of the common signs

J. 12 (Sn. 1.75)

1.75 m.

are also listed to fulfill the prerequisite that ‘the eyes

see what the mind knows’. Both eyes should be

By this time the unfortunate Moses

examined in each case.

was undeceived. He now saw that

The external ocular examination should proceed in

the following order:

J. 14 (Sn. 2.25)

2.25 m.

1. Examination for the head posture

Position of the head and chin should be noted first of

asked the circumstances of

all. Head posture may be abnormal in a patient with

paralytic squint (head is turned in the direction of the

his deception. He sold the

action of paralysed muscle to avoid diplopia) and in

complete ptosis (chin is elevated to uncover the

pupillary area in a bid to see clearly).

Fig. 21.3. Near vision chart.

CLINICAL METHODS IN OPHTHALMOLOGY

467

2. Examination of forehead

- Distichiasis i.e., an abnormal extra row of cilia

Forehead may show increased wrinkling (due to

taking place of meibomian glands.

overaction of frontalis muscle) in patient with

- Madarosis i.e., absence of cilia may be seen in

ptosis.

patients with chronic blepharitis, leprosy and

Complete loss of wrinkling in one-half of the

myxoedema.

forehead is observed in patients with lower motor

- Poliosis i.e., greying of cilia is seen in old age

neuron facial palsy.

and also in patients with Vogt-Koyanagi-

Facial asymmetry may be noted in patient with

Harada’s disease.

Bell’s palsy and facial hemiatrophy.

Scales at lid margins are seen in blepharitis.

Swelling at lid margin may be stye, papilloma or

3. Examination of eyebrows

marginal chalazion.

Level of the two eyebrows may be changed in a

iv. Abnormalities of skin. Common lesions are

patient with ptosis (due to overaction of frontalis).

herpetic blisters, molluscum contagiosum lesions,

Cilia of lateral one-third of the eyebrows may be

absent (madarosis) in patients with leprosy or

warts, epidermoid cysts, ulcers, traumatic scar etc.

myxoedema.

v. Palpebral aperture. The exposed space between

the two lid margins is called palpebral fissure which

4. Examination of the eyelids

measures 28-30 mm horizontally and 8-10 mm vertically

All the four eyelids should be examined for their

(in the centre). Following abnormalities may be

position, movements, condition of skin and lid

observed:

margins.

Ankyloblepharon (horizontally narrow palpebral

i. Position. Normally the lower lid just touches the

fissure) is usually seen following adhesions of

limbus while the upper lid covers about 1/6th (2 mm)

the two lids at angles, e.g., after ulcerative

of cornea.

blepharitis and burns.

In ptosis, upper lid covers more than 1/6th of

Blepharophimosis (all around narrow palpebral

cornea.

fissure) is usually a congenital anomaly.

Upper limbus is visible due to lid retraction as in

Vertically narrow palpebral fissure is seen in:

thyrotoxicosis and sympathetic overactivity.

- Inflammatory conditions of conjunctiva, cornea

ii. Movements of lids. Normally the upper lid follows

and uvea due to blepharospasm

the eyeball in downward movement but it lags behind

- Ptosis (drooping) of upper eyelid

in cases of thyroid ophthalmopathy.

- Enophthalmos (sunken eyeball)

Blinking is involuntary movement of eyelids.

- Anophthalmos (absent eyeball)

Normal rate is 12-16 blinks per minute. It is

- Microphthalmos (congenital small eyeball)

increased in local irritation. Blinks are decreased

- Phthisis bulbi

in trigeminal anaesthesia and absent in those

- Atrophic bulbi

with 7th nerve palsy.

Vertically wide palpebral fissure may be noted

Lagophthalmos is a condition in which the patient

in patients with:

is not able to close his eyelids. Causes of

- Proptosis

lagophthalmos are:

- Large-sized eyeball

- Facial nerve palsy

- Retraction of upper lid

- Extreme degree of proptosis

- Facial nerve palsy

- Symblepharon

iii. Lid margin. Note presence of any of the following:

5. Examination of lacrimal apparatus

Entropion (inward turning of lid margin).

A thorough examination of lacrimal apparatus is

Ectropion (outward turning of lid margin).

indicated in patients with epiphora, corneal ulcer and

Eyelash abnormalities such as:

in all patients before intraocular surgery. The

- Trichiasis i.e., misdirected cilia rubbing the

examination should include:

eyeball. Common causes are trachoma,

Inspect lacrimal sac area for redness, swelling

blepharitis, stye and lid trauma.

or fistula

468

Comprehensive OPHTHALMOLOGY

Inspect the lacrimal puncta, for any defect such

iv. Movements of eyeball should be tested

as eversion, stenosis, absence or discharge.

uniocularly (ductions) as well as binocularly

Regurgitation test. It is performed by pressing

(versions) in all the six cardinal directions of gaze

over the lacrimal sac area just medial to the

(see pages 315).

medial canthus and observing regurgitation of

7. Examination of conjunctiva

any discharge from the puncta. Normally it is

negative. A positive regurgitation test indicates

i. Bulbar conjunctiva can be examined by simply

dacryocystitis. A false negative regurgitation

retracting the upper lid with index finger and lower lid

test may be observed in internal fistula, wrong

with thumb of the left hand.

method of performing regurgitation test, patient

ii. Lower palpebral conjunctiva and lower fornix

might have emptied the sac just before coming to

can be examined by just pulling down the lower lid

the examiner’s chamber, encysted mucocele.

and instructing the patient to look up (Fig. 21.4).

Lacrimal syringing. It is done to locate the

probable site of blockage in patients with epiphora

(see page 368).

Other tests such as Jone’s dye test I and II,

dacryocystography etc. can be performed when

indicated (see page 368).

6. Examination of eyeball as a whole

Observe the following points:

i. Position. Normally, the two eyeballs are

symmetrically placed in the orbits in such a way that

a line joining the central points of superior and inferior

orbital margins just touches the cornea. Abnormalities

of the position of eyeball can be:

(a) Proptosis/exophthalmos i.e., bulging of eyeballs;

note whether proptosis is:

axial or eccentric

reducible or non-reducible

pulsatile or non-pulsatile

Fig. 21.4. Examination of the lower fornix and lower

(b) Enophthalmos (sunken eyeball)

palpebral conjunctiva.

ii. Visual axes of eyeballs. Normally the visual axes

of the two eyes are simultaneously directed at the

iii. Upper palpepral conjunctiva can be examined

only after everting the upper eyelid. Eversion of upper

same object which is maintained in all the directions

lid can be carried out by one-hand or two-hand

of gaze. Deviation in the visual axis of one eye is

technique.

called squint (complete evaluation of a case of squint

One-hand technique. In it patient looks down

is a specialised examination) (see pages 322, 327).

and the examiner grasps the lid margin along with

iii. Size of eyeball. Obvious abnormalities in the size

lashes with left index finger and thumb. Then

of eyeball can be detected clinically. However, precise

swiftly everts the upper lid by making index

measurement of size can only be made by

finger a fulcrum. This, however, requires some

ultrasonography (A-scan). The size of eyeball is

practice.

increased in conditions like buphthalmos and

Two-hand technique. It is comparatively easier.

unilateral high myopia. The causes of small-sized

Procedure is same as above, except that here the

eyeball are: congenital microphthalmos, phthisis

lid is rotated around a fixed probe which is held

bulbi, and atrophic bulbi.

above the level of tarsal plate with right hand

CLINICAL METHODS IN OPHTHALMOLOGY

469

(Fig. 21.5). In slight modification of two-hand

technique, index finger of right hand can be used

instead of probe.

iv. Examination of superior fornix requires double

eversion of upper lid using Desmarre’s lid retractor.

Conjunctival signs

Normal conjunctiva is a thin semi-transparent

structure. A fine network of vessels is distinctly seen

in it. Following signs may be observed:

i. Discoloration of conjunctiva may be brownish in

melanosis and argyrosis (silver nitrate deposits),

greyish due to surma deposits, pale in anaemia,

bluish in cyanosis and bright red due to

subconjunctival haemorrhage.

ii. Congestion of vessels. Congestion may be

superficial

(in conjunctivitis) or ciliary/

circumcorneal/deep (in iridocyclitis, and keratitis)

or mixed

(in acute congestive glaucoma).

Differences between conjunctival and ciliary

congestion are depicted in Table 21.2.

iii. Conjunctival chemosis (oedema) may be observed

in allergic and infective inflammatory conditions.

iv. Follicles. These are seen as greyish white raised

areas (mimicking boiled sago-grains) on fornices

and palpebral conjunctiva. Follicles represent

areas of aggregation of lymphocytes. Follicles

may be seen in following conditions:

Trachoma

Acute follicular conjunctivitis

Chronic follicular conjunctivitis

Benign (School) folliculosis

Fig. 21.5. Two-hand technique of upper lid eversion.

Table 21.2. Differences between conjunctival and ciliary congestion

S. no. Feature

Conjunctival congestion

Ciliary congestion

Site

More marked in the fornices

More marked around the limbus

Colour

Bright red

Purple or dull red

Arrangement of vessels

Superficial and branching

Deep and radiating from limbus

On moving conjunctiva

Congested vessels also move

Congested vessels do not move

On mechanically squeezing out Vessels fill slowly from

Vessels fill rapidly from

the blood vessels

fornix towards limbus

limbus towards fornices

Blanching, i.e., on putting one

Vessels immediately blanch

Do not blanch

drop of 1 in 10000 adrenaline

Common causes

Acute conjunctivitis

Acute iridocyclitis, keratitis (corneal

ulcer)

470

Comprehensive OPHTHALMOLOGY

Papillae are seen as reddish raised areas with

8. Examination of sclera

flat tops and velvety appearance. These

Normally anterior part of sclera covered by bulbar

represent areas of vascular and epithelial

conjunctiva can be examined under diffuse

hyperplasia. Papillae are seen in following

illumination. Following abnormalities may be seen:

conditions:

i. Discoloration. Normally sclera is white in colour. It

Trachoma

becomes yellow in jaundice. Bluish discoloration may

Spring catarrh

be seen as an isolated anomaly or in association with

Allergic conjunctivitis

osteitis deformans, Marfan’s syndrome, pseudo-

xanthoma elasticum. Pigmentation of sclera is also

Giant papillary conjunctivitis

seen in naevus of Ota, and melanosis bulbi.

vi.

Concretions are seen as yellowish-white hard

looking raised areas, varying in size from pin-

ii. Inflammation. A superficial localised pink or purple

circumscribed flat nodule is seen in episcleritis. While

point to pin-head. They represent inspissated

a deep, dusky patch associated with marked

mucous and dead epithelial cells in glands of

inflammation and ciliary congestion is suggestive of

Henle. Common causes of concretions are

scleritis.

trachoma, conjunctival degeneration and

idiopathic.

iii. Staphyloma is a thinned out bulging area of sclera

which is lined by the uveal tissue. Depending upon

vii.

Foreign bodies are commonly lodged in fornices

its location, scleral staphylomas may be intercalary,

and sulcus subtarsalis on palpebral conjunctiva.

ciliary, equatorial and posterior.

viii.

Scarring on the conjunctiva may be in the form

of a single line in the area of sulcus subtarsalis

iv. Traumatic perforations in blunt trauma are usually

(Arlt’s line), irregular, or star-shaped. Common

seen in the region of limbus or at the equator.

causes of scarring are:

9. Examination of cornea

Trachoma

Loupe and lens examination or preferably slit-lamp

Healed membranous or pseudomembranous

biomicroscopy is a must to delineate corneal lesions.

conjunctivitis

While examining the cornea, a note of following points

Healed traumatic wounds

should be made:

Surgical scars

i. Size. The anterior surface of normal cornea is

ix.

Pinguecula is a degenerative condition of

elliptical with an average horizontal diameter of 11.7

conjunctiva observed in many adult patients. It

mm and vertical diameter of 11 mm. Abnormalities of

is seen on the bulbar conjunctiva, near the

corneal size can be:

limbus, in the form of a yellowish triangular

Microcornea, when the anterior horizontal

nodule resembling a fat drop.

diameter is less than 10 mm. It may occur isolated

Pterygium is a degenerative conjunctival fold

or as a part of microphthalmos.

which encroaches on the cornea in the palpebral

Corneal size also decreases in patients with

area. It must be differentiated from pseudoptery-

phthisis bulbi.

gium (an inflammatory fold of conjunctiva

Megalocornea is labelled when the horizontal

diameter is more than 13 mm. Common causes are

encroaching on cornea).

congenital megalocornea and buphthalmos.

xi.

Conjunctival cysts which may be observed are:

ii Shape (curvature). Normal cornea is like a watch

Retention cyst

glass with a uniform posterior curve in its central area.

Implantation cyst

In addition to biomicroscopy, keratometry and corneal

Lymphatic cyst

topography is required to confirm changes in corneal

Cysticercosis.

curvature. Abnormalities of corneal shape (curvature)

xii.

Conjunctival tumours. A few common tumours

are:

are dermoids, papillomas and squamous cell

Keratoglobus. It is an ectatic condition in which

carcinoma.

cornea becomes thin and bulges out like a globe.

CLINICAL METHODS IN OPHTHALMOLOGY

471

Keratoconus. It is an ectatic condition in which

cornea becomes cone shaped.

Cornea plana i.e., flat curvature of cornea which

may occur in patients with severe hypotony and

phthisis bulbi and rarely as a congenital anomaly.

iii. Surface. Smoothness of corneal surface is

disturbed due to abrasions, ulceration, ectatic scars

and facets. Changes in smoothness of surface can be

detected by slit-lamp biomicroscopy, window reflex

test and Placido’s disc.

Placido’s keratoscopic disc It is a disc painted with

alternating black and white circles (Fig. 21.6). It may

be used to assess the smoothness and curvature of

corneal surface. Normally, on looking through the

hole in the centre of disc a uniform sharp image of the

circles is seen on the cornea (Fig. 21.7). Irregularities

in the corneal surface cause distortion of the circles

(Fig. 21.8).

Fig. 21.6. Placido’s disc.

iv. Sheen. Normal cornea is a bright shining structure.

Sheen of corneal surface is lost in ‘dry eye’ conditions.

A loss of the normal polish of the corneal surface

causes loss in the sharpness of the outline of the

image of circles on Placido’s disc test.

v. Transparency of cornea is lost in corneal oedema,

opacity, ulceration, dystrophies, degenerations,

vascularization and due to deposits in the

cornea.

Examination for corneal ulcer. Once corneal ulcer is

suspected, a thorough biomicroscopic examination

before and after fluorescein staining should be

performed to note the site, size, shape, depth, floor

Fig. 21.7. Placido’s disc reflex from normal cornea.

and edges of the corneal ulcer.

Examination for corneal opacity is best done with

the help of a slit-lamp. Note the number, site, size,

shape, density (nebular, macular or leucomatous) and

surface of the opacity.

vi. Corneal vascularization. The cornea is an

avascular structure but its vascularization may occur

in many diseases. When vessels are present, an exact

note of their position, whether superficial or deep

and their distribution whether localised, general, or

peripheral should be made.

Differences between superificial and deep

vascularization of cornea are shown in Table 21.3.

vii. Corneal sensations. Cornea is a very sensitive

Fig. 21.8. Placido’s disc reflex from irregular

corneal surface.

structure, being richly supplied by the nerves. The

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Comprehensive OPHTHALMOLOGY

Table 21.3. Differences between superficial and deep corneal vascularization.

Superficial corneal vascularization

Deep corneal vascularization

Corneal vessels can be traced over the limbus into the

Corneal vessels abruptly end at the limbus.

conjunctiva.

Vessels are bright red and well-defined.

Vessels are ill-defined and cause only a diffuse

reddish blush.

Superficial vessels branch in an arborescent manner.

Deep vessels run parallel to each other in a radial

fashion.

Superficial vessels raise the epithelium and make the

Deep vessels do not disturb the corneal surface.

corneal surface irregular.

sensitivity of cornea is diminished in many affections

2. Bengal rose

(1%) stains the diseased and

of the cornea, viz., herpetic keratitis, neuroparalytic

devitalized cells red, e.g., as in superficial punctate

keratitis, leprosy, diabetes mellitus, trigeminal block

keratitis and filamentary keratitis. Bengal rose

for post-herpetic neuralgia and absolute glaucoma.

dye is very irritating. Therefore, a drop of 2%

To test the corneal sensations, patient is asked to

xylocaine should be instilled before using this

look ahead; the examiner touches the corneal surface

dye.

with a fine twisted cotton (which is brought from the

3. Alcian blue dye stains the excess mucus

side to avoid menace reflex) and observes the blinking

selectively, e.g., as in keratoconjunctivitis sicca.

response. Normally, there is a brisk reflex closure of

10. Examination of anterior chamber

lids. Always compare the effect with that on the

opposite side. The exact qualitative measurement of

It is best done with the help of a slit-lamp.

corneal sensations is made with the help of an

i. Depth of anterior chamber. Normal depth of anterior

aesthesiometer.

chamber is about 2.5 mm in the centre (slightly shallow

viii. Back of cornea should be examined for keratic

in childhood and in old age). On slit-lamp

biomicroscopy, an estimate of depth is made from the

precipitates (KPs) which are cellular deposits and a

position of iris. Anterior chamber may be normal,

sign of anterior uveitis.

shallow, deep or irregular in depth.

KPs can be of different types such as fine,

pigmented, or mutton fat (see page 142).

Causes of shallow anterior chamber

ix. Corneal endothelium. It is examined with specular

Primary narrow angle glaucoma

microscope which allows a clear morphological study

Hypermetropia

of endothelial cells including photographic

Postoperative shallow anterior chamber

(after

documentation. The cell density of endothelium is

intraocular surgery due to wound leak or cilio-

around 3000 cells/mm² in young adults, which

choroidal detachment).

decreases with advancing age.

Malignant glaucoma

Anterior perforations

(perforating injuries or

Biomicroscopic examination after staining of

perforation of corneal ulcer).

cornea with vital stains

Anterior subluxation of lens

1. Fluorescein staining of cornea is carried out

Intumescent (swollen) lens

either using one drop of 2 percent freshly prepared

aqueous solution of the dye or a disposable

Causes of deep anterior chamber

autoclaved filter paper strip impregnated with the

Aphakia

dye. The area denuded of epithelium due to

Total posterior synechiae

abrasions or corneal ulcer is stained brilliant

Myopia

green with fluorescein. When examined using

Keratoglobus

cobalt blue light the stained area appears opaque

Buphthalmos

green.

Keratoconus

CLINICAL METHODS IN OPHTHALMOLOGY

473

Anterior dislocation of lens into the anterior

i. Colour of the iris. It varies in different races; it is

chamber.

light blue or green in caucasians and dark brown in

Posterior perforation of the globe.

orientals. Other colour variations are:

Congenital heterochromia iridum (different colour

Causes of irregular anterior chamber

of two irises) and heterochromia iridis (different

Adherent leucoma

colour of sectors of the same iris) may be present

Iris bombe formation due to annular synechiae

in some individuals.

Tilting of lens in subluxation

Greyish atrophic patches are seen in healed

iridocyclitis.

ii. Contents of anterior chamber. Anterior chamber

Darkly pigmented spots

(naevi) are common

contains transparent watery fluid—the aqueous

freckles on the iris.

humour. Any of the following abnormal contents may

be detected on examination:

ii. Pattern of normal iris is peculiar due to presence

of collarette, crypts and radial striations on its anterior

Blood in the anterior chamber is called hyphaema

surface. This pattern is disturbed due to ‘muddy iris’

and may be seen after ocular trauma, surgery,

in acute iridocyclitis and due to atrophy of iris in

herpes zoster and gonococcal iridocyclitis.

healed iridocyclitis.

Pus in the anterior chamber (hypopyon) may be

seen in cases of corneal ulcer, iridocyclitis,

iii. Persistent pupillary membrane (PPM) is seen

endophthalmitis and panophthalmitis.

sometimes as abnormal congenital tags of iris tissue

adherent to the collarette area.

Aqueous flare in anterior chamber occurs due to

collection of inflammatory cells and protein

iv. Synechiae i.e., adhesions of iris to other intraocular

particles in patients with iridocyclitis. Aqueous

structures may be seen. Synechiae may be anterior

flare is demonstrated in fine beam of slit-lamp

(in adherent leucoma) or posterior (in iridocyclitis).

light as fine moving

(Brownian movements)

Posterior synechiae may be total, annular (ring), or

suspended particles. It is based on the Tyndall

segmental.

phenomenon (see page 143).

v. Iridodonesis (tremulousness of the iris). It is

Pseudohypopyon due to collection of tumour

observed when its posterior support is lost as in

cells in anterior chamber may be seen in patients

aphakia and subluxation of lens.

with retinoblastoma.

vi. Nodules on the iris surface. These are observed

Foreign bodies—wooden, iron, glass particles,

in granulomatous uveitis (Koeppe’s and Busacca’s

stone particles, cilia etc. may enter the anterior

nodules), melanoma, tuberculoma and gumma of the

chamber after perforating trauma.

iris.

Crystalline lens may be observed in anterior

vii. Rubeosis iridis (new vessel formation on the iris).

chamber after anterior dislocation of lens.

It may occur in patients with diabetes mellitus, central

Lens particles in anterior chamber after trauma,

retinal vein occlusion and chronic iridocyclitis.

planned extracapsular cataract extraction (ECCE)

viii. A gap or hole in the iris. It may be congenital

is a frequent observation.

coloboma or due to iridectomy (surgical coloboma).

Parasitic cyst e.g., cysticercus cellulosae has

Separation of iris from ciliary body is called

been demonstrated in anterior chamber.

iridodialysis.

Artificial lens. Anterior chamber intraocular lens

ix. Aniridia or irideremia (complete absence of iris).

may be observed in patients with pseudophakia.

It is a rare congenital condition.

iii. Examination of angle of anterior chamber is

x. Iris cyst. It may be seen near the pupillary margin

performed with the help of a gonioscope and slit lamp.

in patients using strong miotic drops.

Gonioscopy is a specialized examination required in

12. Examination of pupil

patients with glaucoma (see page 546).

Note the following points:

11. Examination of the iris

i. Number. Normally there is only one pupil. Rarely,

It should be performed with reference to following

there may be more than one pupil. This congenital

points:

anomaly is called polycoria.

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Comprehensive OPHTHALMOLOGY

ii. Location. Normally pupil is placed almost in the

Greyish white in immature senile cortical cataract;

centre (slightly nasal) of the iris. Rarely, it may be

Pearly white in mature cortical cataract;

congenitally eccentric (corectopia).

Milky white in hypermature cataract;

Brown in cataracta brunescence, and

iii. Size. Normal pupil size varies from 3 to 4 mm

Brownish black in cataracta nigra.

depending upon the illumination. But it may be

Leucocoria (white reflex in pupil) in children is

abnormally small (miosis) or large (mydriasis).

seen in congenital cataract, retinoblastoma,

Causes of miosis

retrolental fibroplasia (retinopathy of prematurity),

Effect of local miotic drugs (parasympathomi-

persistent primary hyperplastic vitreous and

metic drugs).

toxocara endophthalmitis. The yellowish white,

Effect of systemic morphine.

semidilated, non-reacting pupil seen in

Iridocyclitis (narrow, irregular, non-reacting pupil).

retinoblastoma and pseudogliomas is also called

Horner’s syndrome.

as amaurotic cat’s eye reflex.

Head injury (pontine haemorrhage).

Greenish hue is observed in pupillary area in

Senile rigid miotic pupil.

some patients with glaucoma.

Due to effect of strong light.

Dirty white exudates may occlude the pupil

During sleep pupil is pinpoint.

(occlusio pupillae) in patients with iridocyclitis.

Causes of mydriasis

vi. Pupillary reactions. Note as follows:

Effect of topical sympathomimetic drugs (e.g.,

The direct light reflex. To elicit this reflex the

adrenaline and phenylephrine).

patient is seated in a dimlighted room. With the

Effect of topical parasympatholytic drugs (e.g.,

help of a palm one eye is closed and a narrow

atopine, homatropine, tropicamide and

beam of light is shown to other pupil and its

cyclopentolate).

response is noted. The procedure is repeated

Acute congestive glaucoma (vertically oval large

for the second eye. A normal pupil reacts briskly

immobile pupil).

and its constriction to light is well maintained.

Absolute glaucoma.

The consensual light reflex. To determine

Optic atrophy.

consensual reaction to light, patient is seated in

Retinal detachment.

a dimly-lighted room and the two eyes are

Internal ophthalmoplegia.

separated from each other by an opaque curtain

3rd nerve paralysis.

kept at the level of nose (either hand of examiner

Belladonna poisoning.

or a piece of cardboard). Then one eye is

exposed to a beam of light and pupillary response

iv. Shape. Normal pupil is circular in shape.

is observed in the other eye. The same

Irregular narrow pupil is seen in iridocyclitis.

procedure is repeated for the second eye.

Festooned pupil is the name given to irregular

Normally, the contralateral pupil should also

pupil obtained after patchy dilatation (effect of

constrict when light is thrown onto one pupil.

mydriatics in the presence of segmental posterior

Swinging flash light test. It is performed when

synechiae).

relative afferent pathway defect is suspected in

Vertically oval pupil

(pear-shaped pupil or

one eye (unilateral optic nerve lesion with good

updrawn pupil) may occur post-operatively due

vision). To perform this test, a bright flash light

to incarceration of iris or vitreous in the wound

is shone on to one pupil and constriction is

at 12 O’clock position.

noted. Then the flash light is quickly moved to

v. Colour. Of course, pupil is a hole in the iris, but the

the contralateral pupil and response noted. This

pupillary area does exhibit colour depending upon

swinging to-and-fro of flash light is repeated

the condition of the structures located behind it. Pupil

several times while observing the pupillary

looks:

response. Normally, both pupils constrict

Greyish black normally,

equally and the pupil to which light is transferred

Jet black in aphakia;

remains tightly constricted. In the presence of

CLINICAL METHODS IN OPHTHALMOLOGY

475

relative afferent pathway defect in one eye, the

distant direct ophthalmoscopy. In the presence

affected pupil will dilate when the flash light is

of substantial degree of subluxation, half pupil

moved from the normal eye to the abnormal

may be phakic and half aphakic (and patient may

eye. This response is called

‘Marcus Gunn

experience unilateral diplopia). Common causes

pupil’ or a relative afferent pupillary defect

of subluxation of lens are trauma. Marfan’s

(RAPD). It is the earliest indication of optic

syndrome, homocystinuria, Weill-Marchesani

nerve disease even in the presence of normal

syndrome.

visual acuity.

Aphakia (absence of lens) is diagnosed by jet

The near reflex. In it pupil constricts while

black pupil, deep anterior chamber, empty patellar

looking at a near object. This reflex is largely

fossa on slit lamp biomicroscopy, hypermetropic

determined by the reaction to convergence but

eye on ophthalmoscopy and absence of 3rd and

accommodation also plays a part.

4th Purkinje images.

To determine the near reflex, patient is asked

Pseudophakia. When posterior chamber IOL is

to focus on a far object and then instructed

present it is diagnosed by a black pupil, deep

suddenly to focus at an object (pencil or tip of

anterior chamber, shining reflexes from the anterior

index finger) held about 15 cm from patient’s

surface of IOL and presence of all the four

eye. While the patient’s eye converges and

Purkinje’s images. Examination after dilatation of

focuses the near object, observe the constriction

pupil confirms pseudophakia.

of pupil.

ii. Shape of lens. Normal lens is a biconvex structure,

Abnormal pupillary reactions include (i) amaurotic

which is nicely demonstrated in an optical section of

pupil, (ii) efferent pathway defect, (iii) Wernicke’s

the lens on slit-lamp examination (Fig. 21.9). The

hemianopic pupil, (iv) Marcus Gunn pupil, (v) Argyll

optical section of the lens shows from within outward

Robertson pupil, and (vi) the tonic pupil (for details

embryonic, foetal, infantile and adult nuclei, cortex

see page 292).

and capsule. An anterior Y-shaped and posterior

13. Examination of the lens

inverted Y-shaped sutures may also be seen.

A thorough examination of the lens can be

Abnormalities in the lens shape may be:

accomplished with the help of oblique illumination,

Spherophakia i.e., spherical lens.

slit-lamp biomicroscopy and distant direct

Lenticonus anterior i.e., an anterior cone-shaped

ophthalmoscopy with fully-dilated pupils. Following

bulge in the lens.

points should be noted:

i. Position. A normal lens is positioned in the patellar

fossa (space between the vitreous and back of iris)

by the zonules. Abnormalities of position may be:

Dislocation of lens i.e., lens is not present in its

normal position (i.e., patellar fossa) and all its

supporting zonules are broken. In anterior

dislocation the intact lens (clear or cataractous)

is present in the anterior chamber. While in

posterior dislocation the lens is present in

vitreous cavity where it might be floating (lensa

nutans) or fixed to retina (lensa fixata).

Subluxation of lens i.e., lens is partially displaced

from its position. Here zonules are intact in some

quadrant and lens is shifted on that side. With

dilated pupil, edge of subluxated lens is seen as

shining golden crescent on focal illumination and

Fig. 21.9. Optical section of the cornea and adult lens

as a dark line (due to total internal reflection) on

as seen on slit-lamp examination.

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Comprehensive OPHTHALMOLOGY

Lenticonus posterior i.e., a cone-shaped bulge in

vi. Purkinje images test. This test does not have

the posterior aspect of lens.

much significance and thus is not frequently employed

Coloboma of lens i.e., a notch in the lens.

in clinical practice. However, it is described as a tribute

to the original worker who used this test to diagnose

iii. Colour. On focal illumination the normal lens in

mature cataract and aphakia. Normally, when a strong

young age appears almost clear or gives a faint blue

beam of light is shown to the eye, four images

hue.

(Purkinje images) are formed from the four different

In old age even the clear lens gives greyish

reflecting surfaces, viz., anterior and posterior

white hue due to marked scattering of light as a

surfaces of cornea and anterior and posterior surfaces

result of increased refractive index of lens with

of lens (Fig. 21.10). In patients with mature cataract,

advancing age. It is usually mistaken for cataract.

fourth image (formed by posterior surface of lens) is

In cortical cataract lens may be greyish white,

absent i.e., three Purkinje images are formed and in

pearly white or milky white in colour in immature,

aphakia third as well as fourth Purkinje images (formed

mature and hypermature cataracts, respectively.

by anterior and posterior surface of lens) are absent

In nuclear cataract lens may look brown or black

i.e., only two images are formed.

in colour.

A rusty

(orange) discoloration is seen in

cataractous lens with siderosis bulbi

(due to

retained intraocular iron foreign body).

iv. Transparency. Normal lens is a transparent

structure. Any opacity in the lens is called cataract,

which looks greyish or yellowish white on focal

illumination. On distant direct ophthalmoscopy the

lenticular opacities appear black against a red fundal

reflex. On slit-lamp biomicroscopy the morphology

of cataract can be studied in detail:

A complicated cataract in the early stages

exhibits polychromatic lustre and gives bread

crumb appearance.

A true diabetic cataract presents ‘snow flake’

opacities.

A typical ‘sunflower cataract’ is seen in disorder

of copper metabolism (Wilson’s disease).

An early and late ‘rosette-shaped cataract’ is

typical of concussion injury of lens.

v. Deposits on the anterior surface of lens may be:

Vossius ring. It is a small ring-shaped pigment

dispersal seen on the anterior surface of lens

Fig. 21.10. Purkinje images

after blunt trauma.

Pigmented clumps may be deposited on lens in

14. The intraocular pressure (IOP)

patients with iridocyclitis.

The measurement of IOP (ocular tension) should be

Dirty white exudates may be present on lens in

made in all suspected cases of glaucoma and in routine

patients with uveitis and endophthalmitis.

after the age of 40 years. A rough estimate of IOP can

Deposition of ferrous ions

(rusty deposits) is

be made by digital tonometry. For this procedure

seen in siderosis bulbi.

patient is asked to look down and the eyeball is

Deposition of copper ions (greenish deposits) is

palpated by index fingers of both the hands, through

seen in chalcosis.

the upper lid, beyond the tarsal plate. One finger is

CLINICAL METHODS IN OPHTHALMOLOGY

477

kept stationary which feels the fluctuation produced

Observations during fundus examination

by indentation of globe by the other finger (Fig.

During fundus examination following observations

21.11). It is a subjective method and needs experience.

should be made:

When IOP is raised, fluctuation produced is feeble or

1. Media. Normally the ocular media is transparent.

absent and the eyeball feels firm to hard. When IOP

Opacities in the media are best diagnosed by distant

is very low eye feels soft like a partially filled water

direct ophthalmoscopy, where the opacities look black

bag.

against the red glow.

Causes of opacities in media are: corneal opacity,

lenticular opacity, vitreous opacities (may be

exudates, haemorrhage, degeneration, foreign bodies

and vitreous membranes).

Optic disc

Size (diameter) of the optic disc is 1.5 mm which

looks roughly 15 times magnified during direct

ophthalmoscopy. Disc is slightly smaller in

hypermetropes and larger in myopes.

Shape of the normal disc is circular. In very high

astigmatism, disc looks oblong.

Margins of the disc are well defined in normal

cases. Blurring of the margins may be seen in

papilloedema, papillitis, postneuritic optic atrophy

and in the presence of opaque nerve fibres.

Colour. Normal disc is pinkish with central pallor

area.

(i) Hyperaemia of disc is seen in

papilloedema and papillitis, (ii) Paler disc is a sign

of partial optic atrophy, (iii) Chalky-white disc is

seen in primary optic atrophy, (iv) Yellow-waxy

Fig. 21.11. Technique of digital tonometry.

disc is typical of consecutive optic atrophy.

The exact measurement of IOP is done by an

Cup-disc ratio. Normal cup disc ratio is 0.3. (i)

instrument called tonometer. Indentation (Schiotz

Large cup may be physiological or glaucomatous.

tonometer) and applanation (e.g., Goldmann’s

(ii) Cup becomes full in papilloedema and papillitis.

tonometer) tonometers are frequently used (for

Splinter haemorrhages on the disc may be seen

detailed techniques see pages 479-481).

in primary open angle glaucoma and papilloedema.

Normal IOP range is 10-21 mm of Hg with an average

Neovascularization of the disc may occur in

tension of 16 ± 2.5 mm of Hg. When IOP is less than

diabetic retinopathy and sickle-cell retinopathy.

10 mm of Hg, it is called hypotony. An IOP of more

Opticociliary shunt is a sign of orbital

than 21 mm of Hg should always arouse suspicion of

meningioma.

glaucoma and such patients should be thoroughly

Peripapillary crescent is seen in myopia.

investigated.

Kesten-Baum index refers to ratio of large blood

vessels versus small blood vessels on the disc.

III. FUNDUS EXAMINATION

Normal ratio is 4:16. This ratio is decreased in

patients with optic atrophy.

This is essential to diagnose the diseases of the

vitreous, optic nerve head, retina and choroid. For

3. Macula. The macula is situated at the posterior

thorough examination of the fundus pupils should

pole with its centre (foveola) being about 2 disc

be dilated with 5 per cent phenylephrine and/or 1 per

diameters lateral to temporal margin of disc. Normal

cent tropicamide eye drops. The fundus examination

macula is slightly darker than the surrounding retina.

can be accomplished by ophthalmoscopy (see page

Its centre imparts a bright reflex (foveal reflex).

564) and focal illumination (see page 568).

Following abnormalities may be seen on the macula:

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Comprehensive OPHTHALMOLOGY

Macular hole. It looks red in colour with punched-

Superficial retinal haemorrhage may be found

out margins.

in hypertension, diabetes, trauma, venous

Macular haemorrhage is red and round.

occlusions, and blood dyscrasias.

Cherry red spot is seen in central retinal artery

Deep retinal haemorrhages are typically seen in

occlusion, Tay-Sach’s disease, Niemann-Pick’s

diabetic retinopathy.

disease, Gaucher’s disease and Berlin’s oedema.

Soft exudates

(cotton wool spots) appear as

Macular oedema may occur due to trauma,

whitish fluffy spots with indistinct margins. These

intraocular operations, uveitis and diabetic

may occur in hypertensive retinopathy, toxaemic

maculopathy.

retinopathy of pregnancy, diabetic retinopathy,

Pigmentary disturbances may be seen after

anaemias and collagen disorders like DLE, PAN

trauma, solar burn, age-related macular

and scleroderma.

degeneration (ARMD), central chorioretinitis and

Hard exudates are small, discrete yellowish, waxy

chloroquine toxicity.

areas with crenated margins. Common causes are

Hard exudates. These may be seen in

diabetic retinopathy, hypertensive retinopathy,

hypertensive retinopathy and exudative diabetic

Coats’ disease and circinate retinopathy.

maculopathy.

Colloid bodies also called drusens occur as

Macular scarring. It may occur following trauma

numerous minute, whitish, refractile spots with

and disciform macular degeneration.

pigmented margins, mainly involving the posterior

4. Retinal blood vessels. Normal arterioles are bright

pole. They are seen in senile macular degeneration

red in colour and veins are purplish with a caliber

and Doyne’s honeycomb dystrophy.

ratio of 2: 3. Following abnormalities may be detected:

Pigmentary disturbances may be seen in

Narrowing of arterioles is seen in hypertensive

tapetoretinal dystrophies e.g., retinitis pigmentosa

retinopathy, arteriosclerosis, and central retinal

and healed chorioretinitis.

artery occlusion.

Microaneurysms are seen as multiple tiny dot-

Tortuosity of veins occurs in diabetes mellitus,

like dilatations along the venous end of capillaries.

central retinal vein occlusion and blood

They are commonly found in diabetic retinopathy.

dyscrasias.

Other causes include hypertensive retinopathy,

Sheathing of vessels may be seen in periphlebitis

retinal vein occlusions, Eales’ disease and sickle

retinae, and hypertensive retinopathy.

cell disease.

Vascular pulsations. Venous pulsations may be

Neovascularization of retina occurs in hypoxic

seen at or near the optic disc in 10-20% of normal

people and can be made manifest by increasing

states like diabetic retinopathy, Eales’ disease,

the intraocular pressure by slight pressure with

sickle-cell retinopathy, and following central retinal

the finger on the eyeball. Venous pulsations are

vein occlusion.

conspicuously absent in papilloedema. Arterial

Tumours of fundus include retinoblastoma,

pulsations are never seen normally and are always

astrocytoma and melanomas.

pathological. The true arterial pulsations may be

Peripheral retinal degenerations include lattice

noticed in patients with aortic regurgitation, aortic

degeneration, paving stone degeneration, white

aneurysm and exophthalmic goitre. True arterial

areas with and without pressure.

pulsations are not limited to disc. While a pressure

Retinal holes are seen as punched out red areas

arterial pulse which is seen in patients with very

with or without operculum. These may be round

high IOP or very low blood pressure is limited to

or horse-shoe in shape.

the optic disc.

Proliferative retinopathy is seen as disorganized

5. General background. Normally the general

mass of fibrovascular tissue in patients with

background of fundus is pinkish red in colour.

proliferative diabetic retinopathy, sickle cell

Physiological variations include dark red background

retinopathy, following trauma and in Eales’

in black races and tessellated or tigroid fundus due to

disease.

excessive pigment in the choroid. Following abnormal

Retinal detachment. Retina looks grey, raised

findings may be seen in various pathological states:

and folded.

CLINICAL METHODS IN OPHTHALMOLOGY

479

RECORD OF OPHTHALMIC CASE

alcohol, acetone or by heating the footplate in the

Both right and left eye should be examined and

flame of spirit.

findings should be recorded in ophthalmic clinical

After anaesthetising the cornea with 2-4 per cent

case sheet (Appendix I, page 496).

topical xylocaine, patient is made to lie supine on a

couch and instructed to fix at a target on the ceiling.

Then the examiner separates the lids with left hand

TECHNIQUES OF OCULAR

and gently rests the footplate of the tonometer

EXAMINATION AND DIAGNOSTIC

vertically on the centre of cornea. The reading on

TESTS

scale is recorded as soon as the needle becomes

steady (Fig. 21.13).

OBLIQUE ILLUMINATION

See page 543

TONOMETRY

The intraocular pressure (IOP) is measured with the

help of an instrument called tonometer. Two basic

types of tonometers available are: indentation and

applanation.

Indentation tonometery

Indentation (impression) tonometry is based on the

fundamental fact that a plunger will indent a soft eye

more than a hard eye. The indentation tonometer in

current use is that of Schiotz, who devised it in 1905

and continued to refine it through 1927. Because of

its simplicity, reliability, low price and relative

accuracy, it is the most widely used tonometer in the

world.

Schiotz tonometer. It consists of (Fig. 21.12):

Handle for holding the instrument in vertical

position on the cornea;

Footplate which rests on the cornea;

Plunger which moves freely within a shaft in the

footplate;

Bent lever whose short arm rests on the upper

end of the plunger and a long arm which acts as

a pointer needle. The degree to which the plunger

Fig. 21.12. Schiotz tonometer.

indents the cornea is indicated by the movement

of this needle on a scale; and

It is customary to start with 5.5 gm weight.

Weights: a 5.5 g weight is permanently fixed to

However, if the scale reading is less than 3, additional

the plunger, which can be increased to 7.5 and 10

weight should be added to the plunger to make it 7.5

gm.

gm or 10 gm, as indicated; since with Schiotz

Technique of Schiotz tonometry. Before tonometry,

tonometer the greatest accuracy is attained if the

the footplate and lower end of plunger should be

deflection of lever is between 3 and 4. In the end,

sterilized. For repeated use in multiple patients it can

tonometer is lifted and a drop of antibiotic is instilled.

be sterilized by dipping the footplate in ether, absolute

A conversion table is then used to derive the

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Comprehensive OPHTHALMOLOGY

prism applanates the cornea in an area of 3.06 mm

diameter.

Technique (Fig. 21.14). After anaesthetising the

cornea with a drop of 2 per cent xylocaine and staining

the tear film with fluorescein patient is made to sit in

front of slit-lamp. The cornea and biprisms are

illuminated with cobalt blue light from the slit-lamp.

Biprism is then advanced until it just touches the

apex of cornea. At this point two fluorescent

semicircles are viewed through the prism. Then, the

applanation force against cornea is adjusted until the

inner edges of the two semicircles just touch (Fig.

21.15). This is the end point. The intraocular pressure

is determined by multiplying the dial reading with

ten.

Fig. 21.13. Technique of Schiotz tonometry.

intraocular pressure in mm of mercury (mmHg) from

the scale reading and the plunger weight.

The main advantages of Schiotz tonometer are that

it is cheap, handy and easy to use. Its main

disadvantage is that it gives a false reading when

Fig. 21.14. Technique of applanation tonometry.

used in eyes with abnormal scleral rigidity. False low

levels of IOP are obtained in eyes with low scleral

2. Perkin’s applanation tonometer (Fig. 21.16). This

rigidity seen in high myopes and following ocular

is a hand-held tonometer utilizing the same biprism

surgery.

as in the Goldmann applanation tonometer. It is small,

easy to carry and does not require slit lamp. However,

Applanation tonometry

it requires considerable practice before, reliable

The concept of applanation tonometry was

readings can be obtained.

introduced by Goldmann is 1954. It is based on Imbert-

Fick law which states that the pressure inside a sphere

3. Pneumatic tonometer. In this, the cornea is

(P) is equal to the force (W) required to flatten its

applanated by touching its apex by a silastic

surface divided by the area of flattening (A); i.e., P =

diaphragm covering the sensing nozzle (which is

W/A.

connected to a central chamber containing

The commonly used applanation tonometers are:

pressurised air). In this tonometer, there is a

1. Goldmann tonometer. Currently, it is the most

pneumatic-to-electronic transducer, which converts

popular and accurate tonometer. It consists of a

the air pressure to a recording on a paper-strip, from

double prism mounted on a standard slit-lamp. The

where IOP is read.

CLINICAL METHODS IN OPHTHALMOLOGY

481

Fig. 21.15. End point of applanation tonometry. (A) too small; (B) too large; (C) end point.

TECHNIQUES OF FUNDUS EXAMINATION

A. Ophthalmoscopy, and

B. Slit-lamp biomicroscopic examination of the

fundus by:

Indirect slit-lamp biomiscroscopy,

Hruby lens biomicroscopy,

Contact lens biomicroscopy

For details see page 564-568

Fig. 21.16. Perkin’s hand-held applanation tonometer.

PERIMETRY

The visual field is a three-dimensional area of a

4. Pulse air tonometer is a hand-held, non-contact

subject’s surroundings that can be seen at any one

tonometer that can be used with the patient in any

time around an object of fixation. The extent of normal

position.

visual field with a 5 mm white colour object is superiorly

5. Tono-Pen is a computerised pocket tonometer. It

50^o, inferiorly 70^o, nasally 60^o and temporally 90^o (Fig.

employs a microscopic transducer which applanates

21.17). The field for blue and yellow is roughly 10^o

the cornea and converts IOP into electric waves.

less and that for red and green colour is about 20^o

less than that for white. Perimetry with a red colour

Tonography

object is particularly useful in the diagnosis of

Tonography is a non-invasive technique for

bitemporal hemianopia due to chiasmal compression

determining the facility of aqueous outflow (C-value).

and in the central scotoma of retrobulbar neuritis.

The C-value is expressed as aqueous outflow in

The visual field can be divided into central, and

microlitres per minute per millimetre of mercury. It is

peripheral field (Fig. 21.17):

estimated by placing Schiotz tonometer on the eye

Central field includes an area from the fixation

for 4 minutes. For a graphic record the electronic

point to a circle

30° away. The central zone

Schiotz tonometer is used. C-value is calculated from

contains physiologic blind spot on the temporal

special tonographic tables taking into consideration

side.

the initial IOP (P₀) and the change in scale reading

Peripheral field of vision refers to the rest of the

over the 4 minutes.

area beyond 30° to outer extent of the field of

Clinically, C-value does not play much role in the

vision.

management of a glaucoma patient. Although, in

general, C-values more than 0.20 are considered

Methods of estimating the visual fields

normal, between 0.2 and 0.11 border line, and those

Perimetry. It is the procedure for estimating extent

below 0.11 abnormal.

of the visual fields. It can be classified as below:

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Comprehensive OPHTHALMOLOGY

1. Confrontation method. This is a rough but rapid

and extremely simple method of estimating the

peripheral visual field. Assuming the examiner’s fields

to be within the normal range, they are compared with

patient’s visual fields.

The patient is seated facing the examiner at a

distance of 1 metre. While testing the left eye, the

patient covers his right eye and looks into the

examiner’s right eye. The examiner occludes his left

eye and moves his hands in from the periphery

keeping it midway between the patient and himself.

The patient and the examiner ought to see the hand

simultaneously, for the patient’s field to be considered

normal. The hand is moved similarly from above,

below and from right and left.

2. Lister’s perimeter (Fig. 21.18). It has a metallic

Fig. 21.17. Extent of normal visual field.

semicircular arc, graded in degrees, with a white dot

for fixation in the centre. The arc can be rotated in

Kinetic versus static perimetry

different meridians.

Kinetic perimetry. In this the stimulus of known

The patient is seated facing the arc with his chin

luminance is moved from periphery towards the

firmly in the chin-rest. With one eye occluded, he

centre to establish isopters. Various methods of

fixates the white dot in the centre. A test object

kinetic perimetry are: confrontation method,

(usually white and of size 3 to 5 mm) is moved along

Lister’s perimetery, tangent screen scotometry

the arc from extreme periphery towards the centre,

and Goldmann’s perimetry.

and the point at which the patient first sees the object

Static perimetry. This involves presenting a

is registered on a chart. The arc is moved through 30^o

stimulus at a predetermined position for a preset

each time and 12 such readings are taken. The details

duration with varying luminance. Various methods

of the object regarding its colour and size are noted.

of static perimetry adopted are Goldmann

With the help of this perimeter extent of peripheral

perimetry, Friedmann perimetry, automated

field is charted.

perimetry.

3. Campimetry (scotometry) is done to evaluate the

Peripheral versus central field charting

central and paracentral area (30^o) of the visual field.

Peripheral field charting

The Bjerrum’s screen is used and can be of size 1

Central field charting

metre or 2 metres square (Fig. 21.19). Accordingly,

- Confrontation method

the patient is seated at a distance of 1 metre or 2

- Perimetery: Lister’s, Goldmann’s and automated.

metres, respectively. The screen has a white object

- Campimetry or scotometry

for fixation in its centre, around which are marked

- Goldmann’s perimetry

concentric circles from 5^o to 30^o. The patient fixates

- Automated field analysis

at the central dot with one eye, the other being

Manual versus automated perimetry

occluded. A white target (1-10 mm diameter) is brought

Manual perimetry

in from the periphery towards the centre in various

Automated perimetry

meridians. Initially the physiologic blind spot is

charted, which corresponds to the optic nerve head

A. MANUAL PERIMETRY

and is normally located about 15^o temporal to the

Most of the kinetic methods of field testing are done

fixation point. Dimensions of blind sports are

manually as described below:

horizontally 7-8^o and vertically 10-11^o.

CLINICAL METHODS IN OPHTHALMOLOGY

483

Central/paracentral scotomas can be found in

optic neuritis and open angle glaucoma.

4. Goldmann’s perimeter (Fig. 21.20). It consists of a

hemispherical dome. Its main advantage over the

tangent screen is that the test conditions and the

intensity of the target are always the same. It permits

greater reproducibility.

B. AUTOMATED PERIMETRY

Automated perimeters are computer assisted and test

visual fields by a static method. The automated

perimeters automatically test suprathreshold and

threshold stimuli and quantify depth of field defect.

Commonly used automated perimeters are: Octopus,

Field Master and Humphrey field analyser (Fig. 21.21).

Advantages of automated perimetry over manual

perimetry

Presently, use of manual perimetry has markedly

decreased because of the following advantages of

automated perimetry over manual perimetry:

Automated computerized perimetry offers an

unprecedented flexibility, a level of precision and

consistency of test method that are not generally

possible with manual perimetry.

Fig. 21.18. Lister’s perimeter.

Fig. 21.19. Bjerrum’s screen.

Fig. 21.20. Goldmann’s perimeter.

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Comprehensive OPHTHALMOLOGY

Fig. 21.21. Humphrey field analyser

Fig. 21.22. Stimulus intensity scales compared.

(automated perimeter).

Other important advantages of automated

3. Stimulus size. HFA usually offers five sizes of

perimeters are data storage capability, ease of

stimuli corresponding to the Goldmann perimeter

operation, well controlled fixation, menu driven

stimuli I through V. Unless otherwise instructed, the

software and on line assistance making them

standard target size for automated perimetry is

easy to learn and use.

equivalent to Goldmann size III (4 mm²) white target.

Automated perimetry also provides facility to

4. Stimulus duration. Stimulus duration should be

compare results statistically with normal

shorter than the latency time for voluntary eye

individuals of the same age group and with

movements (about 0.25 seconds). HFA uses a

previous tests of the same individual.

stimulus duration of 0.2 sec. while octopus has 0.1

sec.

Interpertation of automated perimetry print out

field charts

Testing strategies and programes

Before embarking on the interpertation of automated

The visual threshold is the physiologic ability to

perimetry printout field charts, it will be worth while

detect a stimulus under defined testing conditions.

to have a knowledge about:

The normal threshold is defined as the mean threshold

Automated perimeter variables and

in normal people in a given age group at a given

Testing strategies and programmes

location in the visual field. It is against these values

The following description is mainly based on

that the machine compares the patient’s sensitivity.

Humphrey’s field Analyser (HFA).

Thresholds are reported is decibels in a range of

0-50. Fifty decibels (db) is the dimmest target the

Automated perimeter variables

perimeter can project. 0 db is the brightest illumination

1. Background illumination. HFA uses 31.5 apostilb

the perimeter can project. The lower the decibel value

(asb) background illumination. Apostilb (asb) is a unit

the lower the sensitivity; the higher the decibel value,

of brightness per unit area (and is defined as 35^-1

the higher is the sensitivity.

candela / m²).

Two basic testing strategies are used in automated

static perimetry:

2. Stimulus intensity. HFA uses projected stimuli

which can be varied in intensity over a range of more

A. Suprathreshold testing. It uses targets that are

than 5% log units (51 decibels) between 0.08 and

well above the brightness that the patient should be

10,000 asb. In decibel notation (db), the value refers

able to see (suprathreshold). It is simply a screening

to retinal sensitivity rather than to stimulus intensity.

procedure to detect gross defects.

Therefore, 0 db corresponds to 10,000 asb and 51 db

B. Threshold testing. Threshold testing provides

to 0.08 asb (Fig. 21.22). In contrast to kinetic perimetry,

more precise results than suprathreshold testing and

the higher numbers indicate a logarithmic reduction

is thus preferred by most clinicians, although it takes

in test object brightness, and hence greater sensitivity

more time and the equipment often costs more.

of vision (Fig. 21.22).

Strategies used for threshold testing are:

CLINICAL METHODS IN OPHTHALMOLOGY

485

1. Full threshold testing. A full threshold test

1. Central 30-2 test. It offers the most comprehensive

determines the threshold value at each point by the

form of visual field assessment of the central 30

bracketing technique (4-2 on the Humphrey and 4-2-

degrees. It consists of 76 points 6 degrees apart on

1 on the Octopus perimeter). In it, a stimulus is

either side of the vertical and horizontal axes, such

presented at a test point for 0.2 seconds and the

that the inner most points are three degrees from the

machine waits for Yes/No response. If the stimulus is

fixation point.

not seen, the intensity of the stimulus is increased in

2. Central 24-2 test. In it, 54 points are examined. It is

4 db steps till it is seen. Once the threshold is crossed,

near similar to the 30-2 test except that the two

the stimulus intensity is decreased in 2db steps till

peripheral nasal points at 30 degrees on either side of

the stimulus is not seen. A full threshold test is

the horizontal axis are not included while testing the

appropriate for a patient’s first test, because it crosses

central 24 degrees.

the threshold twice (first with a 4 dB increment).

3. Central 10-2 test. When most points in the arcuate

Accurately determinied threshold values make

region between 10 and 30 degrees show marked

subsequent tests easier because it allows the

depression then this test helps to assess and follow-

perimeter to begin with the previous threshold values

up 68 points 2 degrees apart in the central 10 degree

are examined.

for determining future data points. Full threshold test

is, however, a time consuming process.

4. Macular grid test is used when the field is limited

2. Fast Pac. It is a more rapid testing strategy where

to central 5 degrees. This test examines 10 points

the threshold is only crossed once

(in

3dB

spaced on a 29 degree square grid centred on the

increments), but this strategy is often not appropriate.

point of fixation.

3. SITA (Swedish Interactive Threshold Alogarithm).

Evaluation of Humphrey single-field print-out

It is a strategy of threshold testing which dramatically

The standard HFA single field printout is obtained

reduces test time. It is available as SITA - standard

using a software called Statpac printout. For the

and SITA-fast.

purpose of evaluation, the Humphry single-field

printout (Statpac printout) with central 30-2 test can

Test programmes

be studied in eight parts or zones I to VIII as described

The standard test programmes used with static

below (Fig. 21.23):

threshold strategy on the Humphrey’s Field Analyser

I. Patient data and test parameters. At the top of

(HFA) can be grouped as below:

printout page (part I or zone I) are printed:

A. Central field tests

Patients data (name, date of birth, eye (right/

Central 30 - 2 test,

left) pupil size visual acuity).

Central 24 - 2 test,

Test parameters (test name, strategy, stimulus

Central 10 - 2 test,and

used,background)

Macular test

II. Reliability indices. The part II or zone II of the

B. Peripheral field tests

printout shows the reliability indices and test duration

Peripheral 30/60-1,

(Fig. 21.23). The visual field examination is considered

Peripheral 30/60-2,

unreliable if three are more of the following reliability

Nasal step, and

indices have below mentioned values:

Temporal crescent

Fixation losses ≥ 20%,

C. Speciality tests

False positive error ≥ 33%,

Neurological-20,

False negative error ≥ 33%,

Neurological -50,

Short-term fluctuations ≥ 4.0 dB,

Central 10-12, and

Total questions ≥ 400.

Macular test

III. Gray scale simulation of the test data is depicted

D. Custom tests

in zone III or part III of the printout (Fig. 21.23). The

darker the printout, the worse is the field. The gray

Central field tests are more commonly required. These

scale provides the field defects at a glance. However,

include:

486

Comprehensive OPHTHALMOLOGY

capable of revealing the hidden scotomas that

may be present in the overall depressed field.

V. Pattern deviation plots. The two pattern deviation

plots (numeric pattern deviation plot and probability

pattern deviation plot) shown in zone V of the

printout are similar to the total deviation plots except

that here Statpac software has corrected the results

for the changes caused by cataract, small pupil, etc.

VI. Global indices are depicted in the zone VI of the

printout. Global indices refer to some calculations

made by Statpac to provide overall guide lines to help

the practitioner assess the field results as a whole

rather than on point-to-point basis as shown in the

total deviation and pattern deviation plots.

Below mentioned four global indices are provided

with the full threshold program which summerize the

status of the visual field at a glance. Principally, the

global indices are used to monitor progression of

glaucomatous damage rather than for initial diagnosis.

1. Mean deviation (MD). This is the mean difference

(in decibel value) between the normative data for

that age compared with that of collected data. It

Fig. 21.23. Arbitraty division of humphry single field print

is more an indicator of the general depression of

out (statpac printout) with central 30-2 test in sparts

the field. Worse than normal value is indicated

(zones) for the purpose of discription and understanding.

by a negative value.

in general we do not make a diagnosis based on the

2. Pattern standard deviation (PSD). It is a measure

grey scale. The main empahasis on statistical help

of variability within the field i.e, it measures the

shows in zone IV to VIII of the printout (threshold

difference between a given point and adjacent

values).

points. It actually points out towards localized

field loss and is most useful in identifying early

IV. Total deviation plots provide the deviation of

defects. It loses its advantage in marked

patient’s threshold values from that of age corrected

depression.

normal data. The two total deviation plots are numeric

3. Short-term fluctuation (SF). It is a measure of the

value plot and the probability plot (grey scale symbol

variability between two different evaluations of

plot).

the same 10 points in the field. It is not available

Numeric value plot represents the differences in

with SITA strategy. A high SF means either

decibels. A zero value means that the patient has

decreased reliability or an early finding indicative

the expected threshold for that age. Positive

of glaucoma.

numbers reflect points that are more sensitive

4. Corrected pattern standard deviation (CPSD). It

than average for that age; whereas negative

is the PSD corrected for SF. It indicates the

numbers reflect points that are depressed

variability between adjacent points that may be

compared with the average.

due to disease rather than due to intra-test

Probability plot (grey scale symbol plot). In the

variability.

lower part of zone IV of the printout, the total

deviation plot is represented graphically. The

VII. Glaucoma hemifield test (GHT) comapares the

darker the graphic representation. the more

five clusters of points in the upper field (above the

significant it is.

horizontal midline) with the five mirror images in the

Note: In general, the total deviation plot is an

lower field. These clusters of points have been

indicator of the general depression and is not

developed based on the anatomical distribution of

CLINICAL METHODS IN OPHTHALMOLOGY

487

the nerve fibres and are specific to the detection of

Indications. It is indicated in many disorders of ocular

gluacoma. Depending upon the differences between

fundus, viz., (1) Diabetic retinopathy (2) Vascular

the upper and lower clusters of points the following

occlusions; (3) Eales’ disease. (4) Central serous

five messages may be displayed:

retinopathy, (5) Cystoid macular oedema.

Outside normal limits. The GHT outside normal

Technique. The technique of FFA comprises rapidly

limits denotes that either the values between

injecting 5 ml of 10 per cent solution of sterile sodium

upper and lower clusters differ to an extent found

fluorescein dye in the antecubital vein and taking

in less than 1% of the population or any one pair

serial photographs (with fundus camera) of the fundus

of clusters is depressed to the extent that would

of the patient who is seated with pupils fully dilated.

be expected in less than 0.5% of the population.

The fundus camera has a mechanism to use blue light

(420-490 nm wavelength) for exciting the fluorescein

Border line. The GHT is considered border line

present in blood vessels and to use yellow-green filter

when the difference between any one of the

for receiving the fluorescent light (510-530 nm

upper and lower mirror clusters is what might be

wavelength) back for photography.

expected in less than 3% of population.

The first photograph is taken after 5 seconds, then

General reduction in sensitivity. The GHT is

every second for next 20 seconds and every 3-5

considered to have general reduction in sensitivity

seconds for next one minute. The last pictures are

if the best part of visual field is depressed to an

taken after 10 minutes.

extent expected in less than

0.5% of the

Complications. FFA is comparatively a safe

population.

procedure. Minor side effects include: discoloration

Abnormally high sensitivity is labelled when the

of skin and urine, mild nausea and rarely vomiting.

best part of the visual field is such as would be

Anaphylaxis or cardiorespiratory problems are

found in less than 0.5% of the population.

extremely rare. However, a syringe filled with

Within normal limits. GHT is considered within

dexamethasone and antihistaminic drug along with

normal limits when none of the above criteria is

other measures should be kept ready to deal with

met.

such catastrophy.

VIII. Actual threshold values shown in part VIII of

Phase of angiogram. Normal angiogram consists of

the printout

(Fig. 21.23) may be inspected for any

following overlapping phases:

pattern or scotoma when clinical features are

1. Pre-arterial phase. Since the dye reaches the

suspeciant and even if all the seven other parts of

choroidal circulation 1 second earlier than the

the printout are normal. A scotoma by definition is

retinal arteries, therefore in this stage choroidal

the depressed part of the field as compared to the

circulation is filling, without any dye in retinal

surrounding and not as compared to normals. When

arteries.

the actual test threshold values are below 15dB, the

2. Arterial phase. It starts 1 second after prearterial

sensitivity of the test is lost.

phase and lasts until the retinal arterioles are

completely filled.

Diagnosis of glaucoma field defects on HFA

3. Arteriovenous phase. This is a transit phase and

single-field printout

involves the complete filling of retinal arterioles

(See page 220).

and capillaries with a laminar flow along the

retinal veins (Fig. 21.24).

FUNDUS FLUORESCEIN ANGIOGRAPHY

4. Venous phase. In this phase, veins are filling and

Fundus flourescein angiography (FFA) is a valuable

arterioles are emptying. This phase can be

tool in the diagnosis and management of a large

subdivided into early, mid, and late venous phase.

number of fundus disorders.

Abnormalities detected by FFA. In the blood

Basically, FFA gives information by allowing the

fluorescein is readily bound to the albumin. Normally

examiner to study the changes, produced by various

the dye remains confined to the intravascular space

fundus disorders, in the flow of fluorescein dye along

due to the barriers formed by the tight junctions

the vasculature of the retina and choroid.

between the endothelial cells of retinal capillaries

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Comprehensive OPHTHALMOLOGY

Occlusion of retinal or choroidal vasculature, e.g.,

as seen in central retinal artery occlusion and

occlusion of capillaries in diabetic retinopathy.

Loss of vasculature as occurs in patients with

choroideremia and myopic degeneration.

ELECTRORETINOGRAPHY AND

ELECTRO-OCULOGRAPHY

The electrophysiological tests allow objective

evaluation of the retinal functions. These include:

electroretinography (ERG), electro-oculography

(EOG), and visually-evoked response (VER).

Electroretinography (ERG)

Electroretinography (ERG) is the record of changes

in the resting potential of the eye induced by a flash

of light. It is measured in dark adapted eye with the

active electrode (fitted on contact lens) placed on

Fig. 21.24. Normal fluorescein angiogram

the cornea and the reference electrode attached on

(arteriovenous phase).

the forehead (Fig. 21.25).

(inner blood-retinal barrier) and that between the

pigment epithelial cells (outer blood-retinal barrier).

In diseased states abnormalities in the form of

hyperfluorescence and hypofluorescence may be

detected on FFA.

1. Hyperfluorescence. The causes are:

A window defect in RPE due to atrophy shows

background choroidal fluorescence.

Pooling of dye under detached RPE.

Pooling of dye under sensory retina after

breakdown of the outer blood-retinal barrier as

occurs in central serous retinopathy (CSR).

Leakage of dye into the neurosensory retina due

to a breakdown in inner blood-retinal barrier e.g.,

as seen in cystoid macular edema (CME).

Leakage of dye from the choroidal or retinal

neovascularization e.g., as seen in cases of

proliferative diabetic retinopathy, and subretinal

neovascular membrane in age-related macular

degeneration.

Staining i.e., long retention of dye by some tissues

e.g., as seen in the presence of drusen.

Leakage of dye from optic nerve head as seen in

papilloedema.

2. Hypofluorescence. The causes are:

Blockage of background fluorescence due to

abnormal deposits on retina e.g., as seen due to

the presence of retinal haemorrhage, hard

Fig. 21.25. Technique of electroretinogram (ERG)

recording.

exudates and pigmented clumps.

CLINICAL METHODS IN OPHTHALMOLOGY

489

Normal record of ERG consists of the following

2. Extinguished response is seen when there is

waves (Fig. 21.26):

complete failure of rods and cones function e.g.,

a-wave. It is a negative wave possibly arising

advanced retinitis pigmentosa, complete retinal

from the rods and cones.

detachment, central retinal artery occlusion and

b-wave. It is a large positive wave which is

advanced siderosis.

generated by Muller cells, but represents the

3. A negative response indicates gross disturbances

acitivity of the bipolar cells.

of the retinal circulation.

c-wave. It is also a positive wave representing

metabolic activity of pigment epithelium.

Electro-oculography (EOG)

Both scotopic and photopic responses can be

Electro-oculography is based on the measurement of

elicited in ERG. Foveal ERG can provide information

resting potential of the eye which exists between the

about the macula.

cornea (+ve) and back of the eye (-ve).

Technique (Fig. 21.27). Electrodes are placed over

the orbital margin near the medial and lateral canthi.

The patient is asked to move the eye sideways

(medially and laterally) and keep there for few

seconds, during which recording is done. In this

procedure, the electrode near the cornea (e.g.,

electrode placed near lateral canthus, when the eye is

rotated laterally) becomes positive. The recording is

done every minute for 12 minutes. This procedure is

performed first in the dark adapted stage and then

Fig. 21.26. Components of normal electroretinogram

repeated for light adapted stage.

(ERG).

Normally, the resting potential of the eye decreases

during dark adaptation and reaches its peak in light

Uses. ERG is very useful in detecting functional

adaptation.

abnormalities of the outer retina (up to bipolar cell

layer), much before the ophthalmoscopic signs

appear. However, ERG is normal in diseases involving

ganglion cells and the higher visual pathway, such

as optic atrophy.

Clinical applications of ERG

1. Diagnosis and prognosis of retinal disorders such

as retinitis pigmentosa, Leber’s congenital

amaurosis, retinal ischaemia and other chorioretinal

degenerations.

2. To assess retinal function when fundus

examination is not possible, e.g., in the presence

of dense cataract and corneal opacity.

3. To assess the retinal function of the babies

where possibilities of impaired vision is

considered.

Abnormal ERG response. It is graded as follows:

1. Subnormal response. b-wave response is

subnormal in early cases of retinitis pigmentosa

even before the appearance of ophthalmoscopic

signs. A subnormal ERG indicates that a large

Fig. 21.27. Technique of electro-oculography (EOG)

area of retina is not functioning.

and record of normal electro-oculogram.

490

Comprehensive OPHTHALMOLOGY

Interpretation of results. Results of EOG are

go white and white become black) but the overall

interpreted by finding out the Arden ratio as follows:

illumination remains same. The pattern reversal VER

Maximum height of light peak

depends on form sense and thus may give a rough

Arden ratio =

× 100

estimate of the visual acuity.

Minimum height of dark trough

Normal curve values are 185 or above.

Normal versus abnormal record of VER. In normal

Subnormal curve values are less than 150.

VER record, an initial positive wave is followed by a

Flat curve values are less than 125.

negative deflection to be followed by larger

hyperpolarization, before the potential returns to

Uses. Since the EOG reflects the presynaptic function

resting level (Fig. 21.28). Normally, the response is of

of the retina, any disease that interferes with the

the order of 10-25 uV and is fully established by the

functional interplay between the retinal pigment

age of 6 months.

epithelium (RPE) and the photoreceptors will produce

an abnormal or absent light rise in the EOG. Thus,

EOG is affected in diseases such as retinitis

pigmentosa, vitamin A deficiency, retinal detachment

and toxic retinopathies. Hence, EOG serves as a test

that is supplementary and complementary to ERG and

in certain states is more sensitive than the ERG.

VISUALLY EVOKED RESPONSE (VER)

As we know when light falls on the retina, a series of

nerve impulses are generated and passed on to the

visual cortex via the visual pathway. The changes

produced in the visual cortex by these impulses can

be recorded by electroencephalography (EEG) (Fig.

21.28). Thus, visually-evoked response (VER) is

nothing but the EEG recorded at the occipital lobe.

VER is the only clinically objective technique

available to assess the functional state of the visual

system beyond the retinal ganglion cells. Since there

is disproportionately large projection of the macular

area in the occipital cortex, the VER represents the

macula-dominated response. VER is of two types

depending upon the techniques used.

1. Flash VER. It is recorded by using an intense

flash stimulation. It merely indicates that light has

been perceived by the visual cortex. It is not affected

by the opacities in the lens and cornea.

Clinical uses. (i) It can assess the integrity of macula

and visual pathway in infants, mentally retarded and

aphasic patients. (ii) It can distinguish between cases

of organic and psychological blindness (e.g.,

malingering and hysterical blindness). (iii) It can detect

visual potentials in eyes with opaque media.

2. Pattern reversal VER. It is recorded using some

patterned stimulus, as in the checker board. In it the

Fig. 21.28. Technique of recording visually evoked

pattern of the stimulus is changed (e.g., black squares

response (VER) and record of normal VER pattern.

CLINICAL METHODS IN OPHTHALMOLOGY

491

In the lesions affecting the conduction of the nerve

A-scan (Time amplitude). The A-scan produces a

impulse by visual pathway (e.g., retrobulbar neuritis)

unidimensional image and echoes are plotted as

the amplitude is reduced and there is delay in the

spikes.

transmission time. The timing of the response is more

Interpretation of A-scan. (i) The distance between

reliable than the amplitude.

the two echo spikes provides an indirect measurement

of tissue such as eyeball length or anterior chamber

OCULAR ULTRASONOGRAPHY

depth and lens thickness.

Ultrasonography has become a very useful diagnostic

(ii)The height of the spike indicates the strength of

tool in ophthalmology. The diagnostic ophthalmic

the tissue sending back the echo. The cornea, lens

ultrasound is based upon ‘pulse-echo’ technique.

and sclera produce very high amplitude spikes, while

Ultrasonic frequencies in the range of 10 MHz are

the vitreous membrane and vitreous haemorrhage

used for ophthalmic diagnosis. Rapidly repeating

produce lower spikes.

short bursts of ultrasonic energy are beamed into the

B-scan (intensity modulation). B-scan produces two-

ocular and orbital structures. A portion of this signal

dimensional dotted section of the eyeball. The

is returned back to the examining probe (transducer)

from areas of reflectivity. The echoes detected by the

location, size and configuration of the structures is

transducer are amplified and converted into display

easy to interpret.

form. The processed signal is displayed on cathode

Clinical uses of ocular ultrasound

ray tubes in one of the the two modes: A-scan or

1. Biometric studies using A-scan to calculate power

B-scan (Fig. 21.29).

of intraocular lens to be implanted.

2. Assessment of posterior segment in the presence

of opaque media.

3. Study of intraocular and orbital tumours and

other mass lesions.

4. Localization of intraocular and intraorbital foreign

bodies.

RELATED QUESTIONS

Enumerate the causes of sudden painless loss of

(I)

vision.

See page 462

Enumerate the causes of sudden painful loss of

vision.

See page 462

Enumerate causes of gradual painless loss of

vision.

See page 462

Enumerate the causes of gradual painful loss of

vision.

See page 462

What are the causes of transient loss of vision

(amaurosis fugax) ?

(II)

See page 463

Fig. 21.29. Ophthalmic ultrasonic A and B scan

Enumerate the causes of night blindness

machine (I) and diagrammatic depiction of echoes

(nyctalopia).

produced by normal ocular structures

with ‘A’ and ‘B’ scan ultrasonography (II).

See page 463

492

Comprehensive OPHTHALMOLOGY

Enumerate the causes of day blindness

Itching in the eyes is a feature of which disease?

(hamarlopia).

Allergic conjunctivitis

(marked itching is

See page 463

pathognomonic of spring catarrh).

What are the causes of defective vision for near

COMMON OCULAR SIGNS

only?

What are the causes of abnormal head posture?

See page 463

Paralytic squint

Severe ptosis

Name the common causes of black spots in front

of the eyes.

Enumerate the causes of madarosis of eyebrows.

See page 463

Leprosy

Myxoedema

What are the causes of flashes of light in front of

the eyes (photopsia)?

Enumerate the causes of ankyloblepharon.

See page 463

Ulcerative blepharitis

Burns of lid margins

What is the most common cause of micropsia

(small size of objects), macropsia (large size of

Enumerate the causes of narrow palpebral

objects) and metamorphopsia (distorted shape of

fissure.

objects) ?

Oedema of lids

Central chorioretinitis

Ptosis

Enophthalmos

Enumerate the causes of coloured halos.

Anophthalmos

See page 463

Microphthalmos

Enumerate the causes of diplopia.

Phthisis bulbi

See page 463

Atrophic bulbi

What are the causes of watering from the eyes?

Enumerate the causes of wide palpebral aperture.

See page 367

Proptosis

Buphthalmos

Enumerate the common causes of redness of

Congenital cystic eyeball

eyes.

Upper, lid retraction

Conjunctivitis

Facial nerve palsy

Keratitis

Enumerate the causes of lagophthalmos.

Iridocyclitis

Facial nerve palsy

Acute glaucomas

Leprosy

Subconjunctival haemorrhage

Myxoedema

Endophthalmitis

Panophthalmitis

Enumerate the causes of poliosis (greying of eye

lashes).

Ocular injuries

Vogt-Koyanagi-Harada’s disease

What are the common causes of pain in eyes?

Old age

Inflammatory conditions of lids, conjunctiva,

Vitiligo

cornea, uvea, sclera, endophthalmitis, pan-

Albinism

ophthalmitis

Enumerate the causes of circumcorneal

Acute glaucomas

congestion.

Refractive errors

Acute glaucomas

Ocular injuries

Keratitis and corneal ulcer

Asthenopia

Acute iridocyclitis

Enumerate the causes of the foreign body

Enumerate the causes of conjunctival follicles.

sensation.

Trachoma

Conjunctival or corneal foreign bodies

Acute follicular conjunctivitis

Trichiasis

Chronic follicular conjunctivitis

Corneal abrasion

Benign folliculosis

CLINICAL METHODS IN OPHTHALMOLOGY

493

Enumerate the causes of conjunctival papillae.

Intumescent (swollen cataractous) lens

Trachoma

Iris bombe formation

Spring catarrh

Adherent leucoma

Allergic conjunctivitis

Enumerate the causes of deep anterior chamber.

Giant papillary conjunctivitis

Aphakia

Enumerate the causes of concretions.

Total posterior synechiae

Trachoma

Myopia

Keratoglobus

Degenerative conditions

Keratoconus

Idiopathic

Anterior dislocation of lens in the anterior chamber

Enumerate the causes of decreased corneal

Posterior perforation of the globe

sensations.

Buphthalmos

Herpes simplex keratitis

Enumerate the causes of nodules on the iris

Neuroparalytic keratitis

surface.

Leprosy

Granulomatous uveitis (Koeppe’s and Busacca’s

Herpes zoster ophthalmicus

nodules

Absolute glaucoma

Melanoma of the iris

Acoustic neuroma

Tuberculoma

Enumerate the causes of superficial corneal

Gumma

vascularization.

Enumerate the causes of rubeosis

iridis

Trachoma

(neovascularization of iris).

Phlyctenular keratoconjunctivitis

Diabetes mellitus

Rosacea keratitis

Central retinal vein occlusion

Superficial corneal ulcer

Chronic iridocyclitis

Enumerate the causes of deep corneal

Sickle-cell retinopathy

vascularization.

Retinoblastoma

Interstitial keratitis

Enumerate the causes of iridodonesis.

Deep corneal ulcers

Dislocation of lens

Chemical burns

Aphakia

Sclerosing keratitis

Hypermature shrunken cataract

After keratoplasty

Buphthalmos

Enumerate the causes of increased corneal

Enumerate the causes of hyphaema.

thickness.

Ocular injuries

Corneal oedema

Postoperative

Enumerate the causes of abnormal corneal

Herpes zoster iritis

surface.

Gonococcal iritis

Corneal abrasion

Intraocular tumour

Corneal ulcer

Spontaneous (from rubeosis iridis).

Keratoconus

Enumerate the causes of hypopyon.

Enumerate the causes of shallow anterior

Corneal ulcer

chamber.

Iridocyclitis

Primary angle-closure glaucoma

Retinoblastoma

(pseudohypoyon)

Hypermetropia

Endophthalmitis

Malignant glaucoma

Panophthalmitis

Postoperative shallow anterior chamber due to

What is diameter of normal pupil ?

- Leaking wound

Diameter 3 to 4 mm

- Ciliochoroidal detachment

In infancy pupil is smaller than at birth

Corneal perforation

Myopes have larger pupil than hypermetropes

494

Comprehensive OPHTHALMOLOGY

Enumerate the causes of miosis.

Enumerate the causes of Marcus Gunn pupil.

Effect of miotic drugs

(parasympathomimetic

(In swinging flashlight test, the pupil on the diseased

drugs, e.g., pilocarpine)

side dilates on transferring light to it)

Effect of systemic morphine

Optic neuritis

Iridocyclitis (narrow, irregular non-reacting pupil)

Optic atrophy

Horner’s syndrome

Retinal detachment

Head injury (pontine haemorrhage)

Central retinal artery occlusion

Central retinal vein occlusion

Senile rigid miotic pupil

During sleep

Enumerate the causes of subluxation of lens.

Argyll Robertson pupil

Trauma

Poisonings

Marfan’s syndrome

- Alcohol

Homocystinuria

- Barbiturates

Weill-Marchesani syndrome

- Organophosphorus compounds

Enumerate the causes of deposits on anterior

- Morphine

surface of lens.

- Carbolic acid

Vossius ring — pigmented ring seen after blunt

Hyperpyrexia

trauma

Pigment clumps in iridocyclitis

Enumerate the causes of mydriasis.

Rusty (orange) deposits in siderosis bulbi

Topical sympathomimetic drugs such as

adrenaline and phenylephrine

Enumerate the causes of cherryred spot.

Topical parasympatholytic drugs such as

Central retinal artery occlusion

atropine, homatropine, cyclopentolate, tropicamide

Commotio retinae (Berlin’s oedema)

Acute congestive glaucoma (vertically oval, large,

Tay-Sachs’ disease

immobile pupil)

Niemann-Pick’s disease

Absolute glaucoma

Gaucher’s disease

Optic atrophy

Enumerate the causes of macular oedema.

Retinal detachment

Trauma

Internal ophthalmoplegia

Intraocular operations

Third nerve paralysis

Uveitis

Belladonna poisoning

Diabetic maculopathy

Coma

Enumerate the causes of superficial retinal

Sympathetic stimulation

haemorrhages.

- Aortic aneurysm

Hypertensive retinopathy

- Cervical rib

Diabetic retinopathy

- Mediastinal sarcoma, lymphosarcoma,

Central retinal vein occlusion

Hodgkin’s disease and pulmonary carcinoma

Anaemic retinopathy

- Emotional excitement

Leukaemic retinopathy

Severe anaemia

Retinopathy of AIDS

Adie’s tonic pupil is larger than its fellow

Enumerate the causes of soft exudates on the

Enumerate the causes of leukocoria (white reflex

retina.

in pupillary area).

Hypertensive retinopathy

Congenital cataract

Retinopathy of toxaemia of pregnancy

Retinoblastoma

Diabetic retinopathy

Persistent hyperplastic primary vitreous

Anaemic retinopathy

Retrolental fibroplasia

LE, PAN and scleroderma

Toxocara endophthalmitis

Leukaemic retinopathy

Coat’s disease

Retinopathy of AIDS

CLINICAL METHODS IN OPHTHALMOLOGY

495

Enumerate the causes of hard exudates on the

Enumerate the causes of tubular vision.

retina.

Terminal stage of advanced glaucomatous field

Diabetic retinopathy

defect

Hypertensive retinopathy

Advanced stage of retinitis pigmentosa

Coats’ disease

Enumerate the causes of ring scotoma.

Circinate retinopathy

Glaucoma

Enumerate the causes of neovascularization of

Retinitis pigmentosa

retina.

Enumerate the causes of central scotoma.

Diabetic retinopathy

Eales’ disease

Optic neuritis

Sickle-cell retinopathy

Tobacco amblyopia

Central retinal vein occlusion

Macular hole, cyst, degeneration

Enumerate the causes of proliferative retinopathy.

Enumerate the causes of bitemporal hemianopia

Proliferative diabetic retinopathy

Central lesions of chiasma:

Sickle cell retinopathy

Pituitary tumours (common)

Eales’ disease

Suprasellar aneurysms

Ocular trauma

Craniopharyngioma

Differential diagnosis of salt and pepper

Glioma of third ventricle

appearance of fundus.

Meningiomas at tuberculum sellae

Prenatal rubella

Enumerate the causes of homonymous

Prenatal influenza

hemianopia.

Varicella

Optic tract lesions

Mumps

Lateral geniculate body lesions

Congenital syphilis

Lesions involving total fibres of optic radiations

Enumerate the causes of arterial pulsations at

Visual cortex lesions (usually sparing of macula)

the disc.

Enumerate the causes of binasal hemianopia

Visible arterial pulsations are always pathological

Lateral chiasmal lesions:

True pulse waves are seen in:

- Aortic regurgitation

Distension of third ventricle

- Aneurysm

Atheroma of posterior communicating arteries

- Exophthalmic goitre

Enumerate the causes of altitudinal hemianopia

Pressure pulse is seen in:

Altitudinal hemianopia refers to loss of upper or

- Glaucoma

more rarely lower halves of field from pressure

- Orbital tumours

upon the chiasma. Causes are:

What is the significance of venous pulsations at

Early loss in upper half of field—intra or extrasellar

the disc ?

tumours.

Are visible in 10 to 20% of normal people

Early loss in lower half of field—suprasellar

Are absent in papilloedema

tumours.

In which condition capillary pulsations of the optic

Enumerate the causes of quadrantic hemianopia.

disc are seen ?

Are seen in aortic regurgitation as a systolic

Homonymous upper quadrantinopia (pie in the

reddening and diastolic paling of the disc.

sky)—temporal lobe lesions involving lower fibres

Enumerate the causes of enlargement of blind

of optic radiations.

spot.

Homonymous lower quadrantanopia (pie on the

Primary open-angle glaucoma

floor)—anterior parietal lobe lesions involving

Papilloedema

upper fibres of optic radiations.

Medullated nerve fibres

Quadrantic hemianopia also occurs due to lesions

Drusen of the optic nerve

in the occipital cortex involving the calcarine

Juxtapapillary choroiditis

fissure.

Clinical Ophthalmic

CHAPTER

Cases

INTRODUCTION

A case of primary open-angle glaucoma

DISEASES OF THE CONJUNCTIVA

A case of phacomorphic glaucoma

A case of Pterygium

A case of phacolytic glaucoma

DISEASES OF THE CORNEA AND

DISEASES OF THE EYELIDS

SCLERA

A case of blepharitis

A case of corneal ulcer

A case of chalazion

A case of corneal opacity

A case of stye

A case of anterior staphyloma

A case of trichiasis and entropion

DISEASES OF THE UVEAL TRACT

A case of ectropion

A case of acute iridocyclitis

A case of ptosis

A case of chronic iridocyclitis

DISEASES OF THE LACRIMAL APPARATUS

DISEASES OF THE LENS

A case of chronic dacryocystitis

A case of senile cataract

A case of congenital/developmental

DISEASES OF THE ORBIT

cataract

A case of proptosis

A case of aphakia

A case of pseudophakia

SQUINT AND NYSTAGMUS

A case of squint

GLAUCOMA

A case of primary narrow-angle

OCULAR INJURIES

glaucoma

A case blunt trauma

iii. Personal and professional history

INTRODUCTION

iv. Family history

4. General physical and relevant systemic

Clinical case discussion is the most important method

examination

of assessing the students’ clinical acumen. In

5. Ocular examination

ophthalmology practical examinations the students

6. Provisional diagnosis

are supposed to work-up a long case and/or 2 to 3

7. Differential diagnosis, if any

short cases with common eye disorders.

8. List of diagnostic tests required

Presentation of a long case

9. Line of management

Students are supposed to evaluate a long case under

List of long cases. During the eight weeks clinical

following headings:

posting in ophthalmology department, students

1. Name, age, sex, occupation and address of the

should evaluate and write in their clinical case

patient

registers, the common long cases. These include a

2. Chief complaints

case of—cataract, aphakia, pseudophakia, glaucoma,

3. History

iridocyclitis, corneal ulcer (bacterial, viral or fungal),

i. History of present illness

corneal opacity, leukocorea, red eye, chronic

ii. History of past illness

dacryocystitis or epiphora and anterior staphyloma.

500

Comprehensive OPHTHALMOLOGY

Presntation of a short case

Occasionally diplopia may occur due to limitation

Students are required to evaluate a short case under

of ocular movements.

following headings:

Usually there is history of prolonged exposure to

1. Name, age, sex, occupation and address of the

sunny, hot, dusty atmosphere.

patient.

Signs on examination. A wing-shaped fold of

2. Chief complaints with only one or two relevant

conjunctiva encroaching upon the cornea in the area

questions of history.

of palpebral aperture is seen (Fig.4.28), more

3. Ocular examination

commonly on the nasal than the temporal side.

4. Diagnosis and differential diagnosis if any

A fully-developed pterygium consists of three

5. List of important diagnostic tests

parts: head (optical part present on the cornea),

6. Line of management

neck (limbal part) and body (scleral part extending

List of short cases. During clinical posting in the

outdoor (OPD), students should see and evaluate

between limbus and the canthus).

the common short cases. These include a case of—

Pterygium may be progressive or regressive.

chalazion, stye, trichiasis, entropion, ectropion,

- Progressive pterygium is thick, fleshy and

ptosis, blepharitis, symblepharon, pterygium,

vascular with a few infiltrates in the cornea in

pinguecula, phlyctenular conjunctivitis, spring

front of the head (called cap of pterygium).

catarrh, trachoma, Bitot’s spots, xerosis, red eye,

- Regressive pterygium is thin, atrophic, attenuated

corneal ulcer, corneal opacity, arcus senilis, band-

with very little vascularity. There is no cap.

shaped keratopathy, anterior staphyloma, proptosis,

Ultimately it becomes membranous (pterygium

phthisis bulbi, senile cataract (immature, mature,

siccus) but never disappears.

hypermature, nuclear), congenital cataract, traumatic

Differential diagnosis Pterygium must be

cataract, aphakia, pseudophakia, iridocyclitis,

differentiated from pseudopterygium.

absolute glaucoma, fixed dilated pupil, miosed pupil,

amaurotic cat’s eye reflex etc.

RELATED QUESTIONS

Description of clinical cases and viva questions

What is a pterygium ?

Description of common clinical cases and related viva

Pterygium is degenerative condition of the

questions and other miscelaneous viva questions are

subconjunctival tissue which proliferates as

described chapterwise.

vascularized granulation tissue and is characterized

by formation of a triangular fold of conjunctiva

DISEASES OF THE CONJUNCTIVA

encroaching on the cornea.

What is a pseudopterygium; how does it differ from

A CASE OF PTERYGIUM

the pterygium?

CASE DISCRIPTION

Pseudopterygium is a fold of bulbar conjunctiva

attached to the cornea. It is formed due to adhesions

Age and sex. More common in males than females

of chemosed bulbar conjunctiva to the marginal

(2:1) and usually occurs past-middle age.

corneal ulcer. It usually occurs following chemical

Presenting symptoms. Patients usually present with:

A cosmetically unacceptable dirty white growth

burns of the eye.

on the cornea. Usually there are no other

Differences between the pterygium and

symptoms in early stages.

pseudopterygium are as depicted in Table 22.1.

Patient may experience slight irritation or foreign

What complications can occur in an untreated

body sensation.

case of pterygium ?

Diminution of vision may occur due to astigmatism

Cystic degeneration

produced by traction on the cornea. Gross

diminution of vision occurs when it encroaches

Neoplastic change

(rarely) to: epithelioma,

upon the pupillary area.

fibrosarcoma or malignant melanoma.

CLINICAL OPHTHALMIC CASES

501

Table 22.1: Differences between ptergium and

Conjunctival burns

(thermal, chemical or

pseudopterygium

radiational)

Prolonged exposure of conjunctiva as in

Pterygium

Pseudopterygium

lagophthalmos.

1. Aetiology

A degenerative Inflammatory

II. Epithelial xerosis: It occurs due to hypo-

process

vitaminosisA.

2. Age

Usually occurs

Can occur at

in elderly

any age

What is pannus ?

persons

Pannus is infiltration of the cornea associated with

3. Site

Always situated Can occur at

vascularization. In progressive pannus, the

in the palpebral any site

infiltration is seen ahead of the parallel blood vessels,

aperture

4. Stages

Either prog-

Always stationary

while in regressive pannus it stops short and the

ressive,

blood vessels extend beyond the corneal haze.

regressive or

stationary

5. Probe

Probe cannot

A probe can be

DISEASES OF THE CORNEA

test

be passed

easily passed

underneath

under its neck

AND SCLERA

How can we prevent the recurrence after surgical

A CASE OF CORNEAL ULCER

excision of the pterygium?

Recurrence of the pterygium after surgical excision is

CASE DESCRIPTION

the main problem (30-50%). It can be reduced by any

Age and sex. May occur at any age in both the sexes.

of the following measures:

Comparatively males are more commonly affected due

Peroperative use of mitomycin-C

to higher chances of injury to the eyes and exposure

Postoperative use of antimitotic drops such as

to infection because of outdoor activity.

mitomycin-C or thiotepa

Presenting symptoms. A case of corneal ulcer

Surgical excision with bare sclera

presents with pain, photophobia, lacrimation,

Surgical excision with mucous membrane grafts.

discharge, redness, swelling of eyelids and defective

Old methods not used now included:

vision.

- Transposition of pterygium to the lower fornix

Predisposing factors. A meticulous history taking

(MxReynold’s operation) and

may reveal presence of any of the following

- Postoperative beta-irradiation

predisposing factors:

Injury to the eye by vegetative matter, nail, foreign

What is a pinguecula ?

body, etc.

Pinguecula is a degenerative condition of the

Chronic dacryocystitis.

conjunctiva characterized by formation of a yellowish

Acute or chronic conjunctivitis

white triangular patch near the limbus.

Chronic foreign body sensation in the eye as in

trichiasis and concretions.

What are the causes of conjunctival xerosis ?

Contact lens wear

Depending upon the aetiology, conjunctival xerosis

Use of topical steroids

can be divided into two groups:

Diatetes mellitus.

I. Parenchymatous xerosis: It occurs due to

General physical and systemic examination should

cicatricial disorganization of the conjunctiva as

be performed with specific aim to rule out presence of

seen in the following conditions:

vitamin A deficiency, malnutrition, diabetes mellitus,

Trachoma

source of infection in the body including nasal cavity,

Membranous conjunctivitis

paranasal sinuses and teeth and gums.

Stevens-Johnson syndrome

Signs on ocular examination may include (Fig.5.5

Pemphigus

& 5.6):

Pemphigoid

Visual acuity is diminished

502

Comprehensive OPHTHALMOLOGY

Lids show oedema, blepharospasm, lashes may

Define corneal ulcer

be matted and trichiasis may be present

Corneal ulcer may be defined as discontinuation in

sometimes.

the normal epithelial surface of the cornea associated

Lacrimal sac. Regurgitation test is positive when

with necrosis of the surrounding corneal tissue.

there is associated chronic dacryocystitis.

Pathologically, it is characterized by oedema and

Conjunctiva reveals conjunctival as well as

cellular infiltration.

circumcorneal congestion and chemosis.

Classify keratitis

Concretions may be seen on tarsal conjunctiva

Keratitis can be classified in two ways:

due to old trachoma.

topographically and aetiologically.

Cornea on meticulous examination may reveal:

- Loss of normal corneal transparency

Topograhical (morphological) classification

- Corneal ulcer (better seen after staining with

(A) Ulcerative keratitis (corneal ulcer): It can be

2% fluorescein dye) should be described with

further classified variously as follows:

reference to its site, size, shape, depth, margins

1. Depending on location:

and floor. Typical features of the bacterial,

(a) Central corneal ulcer

fungal or viral ulcer may be seen.

(b) Peripheral corneal ulcer

- Window reflex and Placido’s disc reflex are

2. Depending on purulence:

distorted.

(a) Purulent corneal ulcer or suppurative corneal

ulcer

(mostly bacterial and fungal corneal

- Corneal sensations may be diminished or

ulcers are purulent).

absent.

(b) Non-purulent corneal ulcer (most of the viral,

- Superficial peripheral corneal vascularization

chlamydial, allergic and other non-infective

may be seen.

corneal ulcers are non-suppurative).

- A descematocele may sometimes be seen in a

3. Depending upon association of hypopyon:

deep ulcer.

(a) Simple corneal ulcer (without hypopyon)

Anterior chamber may or may not show pus

(b) Hypopyon corneal ulcer

(hypopyon). It is a feature of bacterial as well as

4. Depending upon depth:

fungal corneal ulcers.

(a) Superficial corneal ulcer

Iris may be slightly muddy in colour.

(b) Deep corneal ulcer

Pupil small due to associated toxin-induced iritis.

Intraocular pressure is usually normal. IOP may

(d) Perforated corneal ulcer

be raised if hypopyon or associated uveitis is

5. Depending upon slough formation:

present.

(a) Non-sloughing corneal ulcer

(Note: To record IOP, Schiotz tonometer is never used

(b) Sloughing corneal ulcer

in corneal ulcer. Always non-contact tonometer is

(B) Non-ulcerative keratitis

used)

1. Superficial keratitis

Differential diagnosis. Efforts should be made to

(a) Superficial punctate keratitis

describe the type of corneal ulcer whether bacterial,

(b) Diffuse superficial keratitis

fungal, viral, degenerative or nutritional.

2. Deep keratitis

(a) Non-suppurative

(1) Interstitial keratitis

RELATED QUESTIONS

(2) Disciform keratitis

Define keratitis

(3) Keratitis profunda

Keratitis refers to inflammation of the cornea. It is

(4) Sclerosing keratitis

characterized by corneal oedema, cellular infiltration

(b) Suppurative deep keratitis

and conjunctival reaction, Keratitis may be either

(1) Central corneal abscess

ulcerative or non-ulcerative.

(2) Posterior corneal abscess

CLINICAL OPHTHALMIC CASES

503

Aetiological classification

Name the bacteria which can invade the intact

1. Infective keratitis

corneal epithelium and produce ulceration.

(a) Bacterial

Neisseria gonorrhoeae

(b) Viral

Neisseria meningitidis

Corynebacterium diphtheriae

(d) Chlamydial

Name the layers of cornea.

(e) Protozoal

(f) Spirochaetal

1. Epithelium

2. Allergic keratitis

2. Bowman’s membrane

(a) Phlyctenular keratitis

3. Corneal stroma

(b) Vernal keratitis

4. Descemet’s membrane

5. Endothelium

3. Trophic keratitis

What are the pathological stages of corneal

(a) Exposure keratitis

ulceration?

(b) Neuroparalytic keratitis

1. Stage of progressive infiltration

4. Keratitis associated with diseases of the skin and

2. Stage of active ulceration

mucous membranes.

3. Stage of regression

5. Keratitis associated with systemic collagen

4. Stage of cicatrization

vascular disorders.

6. Traumatic keratitis which may be due to

What are the characteristic features of bacterial

mechanical trauma, chemical burns, radiational

corneal ulcer ?

burns or thermal burns.

A clinical diagnosis of bacterial corneal ulcer is made

7. Idiopathic keratitis, e.g.,

in patients with a greyish white central or marginal

(a) Mooren’s ulcer

ulcer associated with marked pain, photophobia,

(b) Superior limbic keratoconjunctivitis

blepharospasm, lacrimation, circumcorneal

congestion, purulent/mucopurulent discharge,

Name the common bacteria responsible for

presence or absence of hypopyon with or without

corneal ulceration?

vascularization.

Common bacteria associated with corneal ulceration

are: Staphylococcus aureus, Pseudomonas

What do you mean by hypopyon corneal ulcer?

pyocyanea, Streptococcus pneumoniae, E.coli,

A purulent corneal ulcer associated with collection

Proteus, Klebsiella, Neisseria gonorrhoeae, Neisseria

of pus in the anterior chamber is called hypopyon

meningitidis and Corynebacterium diphtheriae.

corneal ulcer.

What is the prerequisite for most of the infecting

Name the common organisms responsible for

agents to produce corneal ulceration?

hypopyon corneal ulceration.

Damage to the corneal epithelium is a prerequisite for

1. Most fungal ulcers are associated with hypopyon.

most of the infecting organisms to produce corneal

2. Common bacteria producing hypopyon ulcer are

ulceration. Damage to corneal epithelium may occur

Pneumococcus, Pseudomonas, Gonococcus and

in following forms:

Staphylococcus.

Corneal abrasion due to small foreign body,

misdirected cilia, trivial trauma, etc.

What is ulcus serpens ?

Necrosis of epithelium as in keratomalacia.

The characteristic hypopyon ulcer caused by

Epithelial damage due to trophic changes as in

pneumococcus is called ulcus serpens.

neuroparalytic keratitis.

Desquamation of epithelial cells as a result of

Name the complications of corneal ulcer

corneal oedema, corneal xerosis and exposure

1. Toxic iridocyclitis

keratitis.

2. Secondary glaucoma

504

Comprehensive OPHTHALMOLOGY

3. Descemetocele

Laboratory investigations

4. Corneal perforation, which may be complicated

1. Routine laboratory investigations such as

by:

haemoglobin, TLC, DLC, ESR, blood sugar and

Iris prolapse

complete urine examination should be carried out

Subluxation or dislocation of the lens

in each case.

Anterior capsular cataract

2. Microbiological investigations: Material is

Purulent iridocyclitis often leading to

obtained by scraping the base and margins of the

endophthalmitis or even panophthalmitis

corneal ulcer (under topical anaesthesia) and is

Intraocular haemorrhage in the form of a

used for following investigations:

vitreous haemorrhage or expulsive choroidal

Gram and Giemsa-stained smears for possible

haemorrhage.

identification of infecting organisms.

5. After healing of corneal ulcer following

10 per cent KOH wet preparation is made for

complications: may be left as sequelae:

identification of fungal hyphae

Keractasia

Culture on blood agar medium for aerobic

Corneal opacity which may be nebular, macular,

organisms

leucomatous or adherent leucoma

Culture on Sabouraud’s dextrose agar medium

Anterior staphyloma which usually follows a

for fungi.

sloughing corneal ulceration

Treatment of uncomplicated corneal ulcer

What is a descemetocele ?

I. Specific treatment for the cause: Bacterial corneal

When a corneal ulcer extends up to Descemet’s

ulcer is treated by topical and systemic antibiotics.

membrane, it herniates (bulges out) as a transparent

1. It is preferable to start concentrated amikacin

vesicle called the descemetocele or keratocele.

(40-100 mg/ml) eyedrops along with fortified

cephazolin

(33 mg/ml) eyedrops every one

What are the signs of an impending corneal

hourly for first five days and then reduced to

perforation?

2 hourly, 3 hourly, 4 hourly and 6 hourly.

Descemetocele formation associated with excessive

2. Antibiotic eye ointment should be applied at

corneal oedema are the signs of an impending corneal

night

perforation.

3. Subconjunctival injection of gentamicin 40 mg

What are the clinical features of perforation of

and cephazolin 125 mg once a day for 5 days

corneal ulcer ?

should be given in sloughing corneal ulcer

Following perforation of a corneal ulcer, immediately

II. Non-specific treatment includes:

pain is decreased and patient feels some hot fluid

1. Cycloplegic drugs, e.g., 1 per cent atropine, 0.5

(aqueous) coming out of the eyes. Anterior chamber

per cent homatropine or cyclopentolate

becomes shallow and iris prolapse may occur.

2. Systemic analgesics and anti-inflammatory

drugs to relieve the pain and oedema

How will you manage a case of corneal ulcer ?

3. Vitamins (A, B-complex and C) help in early

Management of a case of corneal ulcer is as follows:

healing of the ulcer

Clinical evaluation

III. Physical and general measures:

1. Meticulous history should be taken and a

1. Hot fomentation gives comfort, reduces pain

thorough ocular examination including slit-lamp

and causes vasodilatation

biomicroscopy should be carried out to reach at

a clinical diagnosis for the type of corneal ulcer.

2. Rest and good diet are useful for smooth

2. Regurgitation test and syringing of lacrimal sac

convalescence

should be carried out to rule out associated

What do you mean by a non-healing corneal ulcer?

dacryocystitis.

Enumerate its common causes.

3. General physical and systemic examination should

When a corneal ulcer does not start healing despite

be carried out to elucidate the associated

the best therapy for about 7 to 10 days it is labelled

malnutrition, diabetes mellitus and any other

as a non-healing corneal ulcer. Common causes of

chronic debilitating disease.

CLINICAL OPHTHALMIC CASES

505

non-healing corneal ulcers are as follows:

5. Conjunctival flap may be used to cover and

support the weak tissue.

Local causes

6. Bandage soft contact lenses are also useful.

Associated raised intraocular pressure

7. Therapeutic keratoplasty, when available, is

Multiple large concretions

considered the best mode of treatment.

Misdirected cilia

An impacted foreign body

How will you treat a case of perforated corneal

Dacryocystitis

ulcer?

Wrong diagnosis, e.g., fungal ulcer being treated

The best treatment is an immediate therapeutic

as a bacterial ulcer

keratoplasty. However, short of it, depending upon

Lagophthalmos

the size and location of the perforation measures like

Excessive vascularization of the ulcer area

use of a tissue glue (cyanoacrylate), bandage soft

Systemic causes

contact lens or conjunctival flap may be used over

and above the conservative management with

Diabetes mellitus

pressure bandage.

Severe anaemia

Malnutrition

What is a marginal catarrhal ulcer ?

Chronic debilitating diseases

Marginal catarrhal ulcer is a superficial ulcer situated

Immunocompromised patients

near the limbus, usually seen in association with

Patients on systemic steroids

chronic staphylococcal blepharo-conjunctivitis. It is

How will you treat a case of non-healing corneal

thought to be caused by hypersensitivity reaction to

ulcer?

staphylococcal toxins.

1. Removal of any known cause of non-healing: A

Name the common fungi associated with mycotic

thorough search should be made to find out any

corneal ulceration.

already missed cause of non-healing and when

The fungi most commonly responsible for mycotic

found it should be removed.

corneal ulceration are: Aspergillus, Candida and

2. Mechanical debridement of the ulcer to remove

Fusarium.

necrosed material may hasten the healing.

3. Chemical cauterization with pure carbolic acid or

What are the predisposing factors for a mycotic

10 to 20 per cent trichloroacetic acid may be

corneal ulcer ?

considered in indolent cases.

1. Injury by vegetative material.

4. Peritomy, i.e., severing of perilimbal conjunctival

2. Immunosuppressed patients are prone to

vessels may be useful in the presence of excessive

secondary fungal ulcers.

corneal vascularization.

3. Excessive use of topical antibiotics and steroids

What extra measures will you take for the

predispose the cornea for fungal infections.

treatment of impending perforation ?

1. Patient should be advised to avoid strain during

What are the characteristic features of a fungal

corneal ulcer?

sneezing, coughing, passing stool, etc.

2. Pressure bandage should be applied to give some

1. A typical fungal corneal ulcer is dry looking,

external support.

greyish white with elevated rolled-out margins

3. Lowering of intraocular pressure by simultaneous

and delicate feathery finger-like extensions into

use of acetazolamide 250 mg qId orally, 0.5 per

the surrounding stroma under the intact

cent timolol eyedrops twice a day and intravenous

epithelium.

mannitol (20%) drip stat. Even paracentesis with

2. A sterile immune ring (yellow line of demarcation)

slow evacuation of the aqueous from the anterior

may be present where fungal antigen and host

chamber may be done, if required.

antibodies meet.

4. Tissue adhesive glue such as cyanoacrylate is

3. Multiple, small satellite lesions may be present

helpful in preventing perforation.

around the ulcer.

506

Comprehensive OPHTHALMOLOGY

4. Usually a massive and thick hypopyon is present

Sometimes, the branches of the dendritic ulcer

even if the ulcer is very small.

enlarge and coalesce to form a large epithelial ulcer

5. A history of trauma (especially by vegetative

typically known as geographical or amoeboid ulcer.

material) and clinical signs out of proportion to

What are the features of herpes simplex virus

the symptoms, i.e., less marked photophobia and

(HSV)?

lacrimation with intense ciliary and conjunctival

Herpes simplex virus is an epitheliotropic, DNA virus.

congestion support a fungal origin.

It is of two types: HSV type-1 which typically causes

How will you confirm the diagnosis of a fungal

infection above the waist (herpes labialis) and HSV

corneal ulcer ?

type-II which causes infection below the waist (herpes

Confirmation is made by laboratory investigations,

genitalis).

which include examination of a wet KOH, Gram’s and

Name the predisposing/precipitating stress

Giemsa-stained films for fungal hyphae and culture

stimuli which trigger an attack of herpetic keratitis.

on Sabouraud’s dextrose agar medium.

Fever, especially malaria

Name the ocular antifungal drugs.

General ill health

Polyene antifungals, e.g.,

Exposure to ultraviolet rays

1. Nystatin 3.5 per cent eye ointment

Mild trauma

2. Amphotericin-B (0.75 to 3% eyedrops)

Use of topical and systemic steroids

3. Natamycin 5 per cent suspension

Immunosuppression

II. Imidazole antifungal drugs, e.g., ketoconazole,

What is disciform keratitis ?

fluconazole miconazole, clotrimazole and

econazole

Disciform keratitis is stromal keratitis which occurs

III. Pyrimidine, e.g., flucytosine

due to delayed hypersensitivity reaction to the HSV

IV. Silver compounds, e.g., silver sulphadiazine

antigen. It is characterized by a focal disc-shaped

eyedrops

patch of stromal oedema without necrosis.

Associated diminished corneal sensations and fine

Enumerate the ocular lesions of herpes simplex.

keratic precipitates differentiate it from other causes

Ocular involvement by herpes simplex virus (HSV)

of stromal oedema.

occurs in two forms:

Primary herpes - It is characterized by:

Name the antiviral drugs.

1. Vesicular lesions involving the skin of lids

Idoxuridine (IDU), trifluorothymidine (TFT), adenine

2. Acute follicular conjunctivitis

arabinoside (vidarabine) and acyclovir.

3. Fine or coarse epithelial punctate keratitis

Which antiviral drug is effective for stromal viral

II. Recurrent herpes - Its lesions are as follows:

keratitis?

1. Punctate epithelial keratitis

Acyclovir

2. Dendritic ulcer

3. Geographical or amoeboid ulcer

Enumerate the causes of decreased corneal

4. Disciform keratitis

sensations.

Describe the characteristic features of recurrent

Viral keratitis, neuroparalytic keratitis, diabetic

herpetic keratitis.

neuropathy and leprosy.

Dendritic ulcer is a typical epithelial lesion of the

What is herpes zoster ophthalmicus?

recurrent herpetic keratitis. The ulcer is of an irregular

Herpes zoster ophthalmicus is an acute infection of

zigzag linear branching shape (Fig.5.9). The branches

the gasserian ganglion of the fifth cranial nerve by

are generally knobbed at the ends. Floor of the ulcer

varicella zoster virus. In it, frontal nerve is more

stains with fluorescein and the virus laden cells at

frequently affected than the lacrimal and nasociliary

the margin take up rose bengal stain. There is an

nerve. About 50 per cent cases of herpes zoster

associated marked diminution of the corneal

ophthalmicus develop ocular complications.

sensations.

CLINICAL OPHTHALMIC CASES

507

Ocular involvement in herpes zoster

2. Chlamydial infections, e.g., trachoma

ophthalmicus is associated with involvement of

3. Toxic, e.g., in association with blepharo-

which nerve ?

conjunctivitis

Nasociliary nerve.

4. Trophic lesions, e.g., exposure keratitis and

neuroparalytic keratitis

What are the characteristic features of herpes

5. Allergic lesions, e.g., vernal keratitis

zoster?

6. Keratoconjunctivitis sicca

1. Fever and malaise occur at the onset

7. Specific type of idiopathic SPK, e.g., Thygeson’s

2. The vesicular eruptions are preceded by severe

SPK and superior limbic keratoconjunctivitis

neuralgic pain along the course of the involved

8. Photophthalmitis

nerves

3. The lesions are strictly limited to one side of the

What is photophthalmia ?

midline of head (pathognomonic feature)

Photophthalmia refers to occurrence of multiple

epithelial erosions due to exposure to ultraviolet rays

Enumerate the ocular lesions of herpes zoster

having a wavelength of 290-311 mµ. It occurs in the

ophthalmicus.

following conditions:

Conjunctivitis, keratitis, episcleritis, scleritis,

1. Exposure to naked arc light as in industrial welding

iridocyclitis and secondary glaucoma.

and cinema operators

2. Exposure to bright light of a short circuit

What is Mooren’s ulcer ?

3. Snow blindness due to reflected ultraviolet rays

Mooren’s ulcer (chronic serpiginous or rodent ulcer)

from the snow surface

is a peripheral degenerative ulcerative keratitis of

unknown aetiology. It is characterized by a shallow

What is filamentary keratitis/keratopathy? Name

furrow-shaped ulcer having whitish overhanging

its few important causes.

margin at the advancing edge (Fig.5.13).

Filamentary keratitis is a type of superficial punctate

keratitis associated with formation of corneal

What are the features of neuroparalytic keratitis?

epithelial filaments. Its common causes are:

1. No pain, no lacrimation and complete loss of

1. Keratoconjunctivitis sicca (KCS)

corneal sensations

2. Recurrent corneal erosion syndrome

2. Marked ciliary congestion

3. Herpes simplex keratitis

3. Corneal sheen is dull

4. Thygeson’s superficial punctate keratitis

4. Corneal ulcer is usually superficial and involves

5. Prolonged patching of the eye particularly

the interpalpebral area

following ocular surgery like cataract

6. Trachoma

What are the causes of exposure keratitis ?

1. Extreme proptosis

What is interstitial keratitis? What are its common

2. Bell’s palsy

causes ?

3. Symblepharon

Interstitial keratitis is inflammation of the corneal

4. Patients in deep coma

stroma without primary involvement of the epithelium

or endothelium. Its common causes are: congenital

What is superficial punctate keratitis; name a few

syphilis, tuberculosis, acquired syphilis, Cogan’s

of its causes ?

syndrome (interstitial keratitis with acute tinnitus,

Superficial punctate keratitis (SPK) refers to

vertigo and deafness).

occurrence of multiple, spotty lesions in superficial

layer of cornea. Its common causes are:

What are corneal dystrophies ?

1. Viral infections, e.g., adenovirus infection,

Corneal dystrophies are inherited disorders

epidemic keratoconjunctivitis, herpes zoster

characterized by development of corneal haze in

keratitis, herpes simplex keratitis, and

otherwise normal eyes that are free of inflammation

pharyngoconjunctival fever

or vascularization. These are classified as follows:

508

Comprehensive OPHTHALMOLOGY

1. Anterior dystrophies which primarily affect

What are common causes of corneal opacity?

epithelium and Bowman’s membrane, e.g.,

1. Congenital opacities

recurrent corneal erosion syndrome.

2. Healed corneal wounds

2. Stromal dystrophies: These include: granular

3. Healed corneal ulcers

dystrophy, macular dystrophy and lattice

What are the types of corneal opacity?

dystrophy

1. Nebular corneal opacity. It is a faint opacity

3. Posterior dystrophies which primarily affect the

which results due to scars involving up to a few

corneal endothelium and Descemet’s membrane,

superficial lamellae of corneal stroma.

e.g., cornea guttata, Fuchs’ dystrophy

2. Macular opacity. It is a dense opacity produced

4. Ectatic dystrophies e.g., keratoconus, kerato-

by scars involving up to about half the thickness

globus.

of the stroma.

3. Leucomatous corneal opacity (leucoma- simplex).

What is Fuchs’ dystrophy ?

It is a very dense,white opacity, which results

Also called as epithelial endothelial dystrophy,

due to scarring of more than half thickness of

affects females more than the males between 5th and

corneal stroma.

7th decade of life. It is a slowly progressive bilateral

4. Adherent leucoma. It results when healing occurs

condition. Its clinical features can be divided into

after perforation of cornea with incarceration of

following four stages:

the iris.

Stage of cornea guttata

Oedematous stage or stage of endothelial

Name the secondary changes which can occur in

decompensation

a long standing case of corneal opacity.

Stage of bullous keratopathy

1. Hyaline degeneration

Stage of scarring

2. Calcareous degeneration

3. Pigmentation

Define keratoconus and describe its treatment.

4. Atheromatous ulceration

Keratoconus is a non-inflammatory ectatic condition

How will you treat a case with corneal opacity?

of the cornea. It is usually bilateral and manifests at

1. Optical iridectomy. It may be performed in cases

puberty with gradual loss of vision.

with central macular or leucomatous corneal

The high myopic irregular astigmatic refractive

opacities; provided vision improves with pupillary

error seen in keratoconus may be treated by hard

dilatation.

contact lens in early stages. Ultimately penetrating

2. Keratoplasty. It provides good visual results in

keratoplasty is required.

uncomplicated cases with corneal opacities; where

optical iridectomy is not of much use.

A CASE OF CORNEAL OPACITY

3. Tattooing of scar. It used to be performed for

CASE SUMMARY

cosmetic purposes. It is suitable only for firm

Presenting symptoms. A patient with corneal opacity

scars in a quite eye without useful vision.

usually presents with a whitish scar, causing

Presently it is sparingly used.

defective vision as well as cosmetic blemish.

How do you perform tattooing ?

History may reveal a history of trauma to the eye or

First of all, the epithelium covering the opacity is

symptoms suggestive of healed corneal ulceration.

removed under topical anaesthesia. Then a piece of

Examination reveals an opacity on the cornea

blotting paper of the same size and shape soaked in 4

(Fig.5.20) which may be nebular, macular or

per cent gold chloride (for brown eyes) or 2 per cent

leucomatous. The location, size, shape and density

platinum chloride (for dark colour) is applied over it.

of the opacity must be described.

After 2 to 3 minutes the piece of blotting paper is

removed and a few drops of freshly-prepared

RELATED QUESTIONS

hydrazine hydrate (2%) solution are poured over it.

What is a corneal opacity ?

Lastly, eye is irrigated with normal saline and patched

The term corneal opacity is used for the loss of

after instilling antibotic and atropine eye ointment.

corneal transparency due to scarring.

Epithelium grows over the pigmented area.

CLINICAL OPHTHALMIC CASES

509

What are the causes of corneal vascularization?

What is the optimum time for the removal of donor

Normal cornea is avascular. In pathological states,

eyes from the body of a deceased ?

superficial or deep corneal vascularization may occur

The donor eyes should be removed as early as

(Fig.5.22).

possible (within 6 hours of death) and should be

1. Superficial corneal vascularization. In it, vessels

stored under sterile conditions.

are arranged in an arborizing pattern, present

What are the methods of corneal preservation?

below the epithelium and their continuity can be

1. Short-term storage (up to 48 hours): The whole

traced with the conjunctival vessels. Its common

globe is preserved at 4°C in a moist chamber.

causes are:

2. Intermediate storage (up to 2 weeks): The donor

Trachoma

corneal button is prepared and stored in McCarey-

Phlyctenular keratoconjunctivitis

Kaufman (MK) medium and various chondroitin

Superficial corneal ulcers

sulphate-enriched media such as optisol.

Rosacea keratitis

3. Long-term storage (up to 35 days): It is done by

2. Deep corneal vascularization. In it, the vessels

organ culture method or cryopreservation.

are generally derived from the anterior ciliary

arteries and lie in the corneal stroma. These

Enumerate the complications of keratoplasty

vessels are usually straight, not anastomosing

operation.

and their continuity cannot be traced beyond the

I. Early complications are: flat anterior chamber,

limbus. Its common causes are:

iris prolapse, infection, secondary glaucoma,

Interstitial keratitis

epithelial defects, primary graft failure

Disciform keratitis

II. Late complications are: graft rejection, recurrence

Deep corneal ulcers

of disease, marked astigmatism and cystoid

Chemical burns

macular oedema.

Sclerosing keratitis

From which sources cornea derives its nutrition?

Corneal graft vascularization

Perilimbal capillaries

What is keratoplasty ?

Aqueous humour

Keratoplasty is an operation in which the patient’s

Oxygen from atmosphere

diseased cornea is replaced by the donor’s healthy

What is the nerve supply of cornea ?

clear cornea. It is of two types:

1. Lamellar keratoplasty (partial thickness)

Cornea is supplied by the nasociliary branch of the

2. Penetrating keratoplasty (full thickness)

ophthalmic division of the trigeminal nerve.

What is a corneal facet?

Name the indications for keratoplasty.

A corneal facet is a transparent depressed scar. On

Lamellar keratoplasty

slit-lamp examination light beam appears to dip in the

Indolent corneal ulcer, superficial corneal opacity

area of a facet.

and lattice dystrophy.

Penetrating keratoplasty

What is kerotomalacia ?

1. Optical, i.e., to improve vision in patient with

Keratomalacia refers to corneal necrosis due to

corneal opacity, bullous keratopathy, corneal

vitamin A deficiency. In this condition, there is no

dystrophies and advanced keratoconus

inflammatory reaction.

2. Therapeutic, i.e., to replace inflamed cornea not

responding to treatment (indolent deep ulcer)

What is arcus senilis?

3. Tectonic grafts, i.e., to restore the integrity of

Arcus senilis is a degenerative condition of the cornea

eyeball in corneal perforation and marked corneal

characterized by an annular lipid infiltration

thinning

concentric to limbus. The ring of opacity is about

4. Cosmetic, i.e., to improve appearance of the eye

1-mm wide and is separated from the limbus by a clear

in deep leucomas with no vision in the eye.

zone (lucid interval of Vogt).

510

Comprehensive OPHTHALMOLOGY

A CASE OF ANTERIOR STAPHYLOMA

2. In patient where there is a chance of getting

useful vision, keratoplasty (wherever possible)

CASE SUMMARY

or keratoprosthesis may be performed.

Presenting symptoms. Patient presents with loss of

vision, bluish discoloration and bulging of the

What are the causes of posterior staphyloma?

anterior part of the eye.

Pathological myopia

History is suggestive of symptoms of corneal

Posterior scleritis

ulceration (pain, redness, photophobia, watering, loss

Perforating injuries

of vision and whitish discoloration) followed by the

What is episcleritis ? Describe features of a nodule

bluish discoloration and bulging of the anterior part

of episcleritis.

of the eye.

Episcleritis is a benign recurrent inflammation of the

Examination reveals that cornea is replaced by a

episclera, involving the overlying Tenon’s capsule

lobulated ectatic scar tissue which is blackened due

but not the underlying sclera.

to the iris plastered behind it (Fig.5.21).

A typical nodule of episcleritis is flat, pink or

purple, surrounded by injection and is usually

RELATED QUESTIONS

situated 2 to 3 mm away from the limbus.

What is a staphyloma ?

What is the differential diagnosis of nodular

Staphyloma refers to a localized bulging of weak and

episcleritis?

thin outer tunic of the eyeball (cornea or sclera) lined

Inflamed pinguecula

by uveal tissue which shines through the thinned-

Foreign body embedded in the bulbar conjunctiva

out fibrous coat.

Scleritis

What are the types of staphyloma?

1. Anterior staphyloma

DISEASES OF THE UVEAL TRACT

2. Ciliary staphyloma

A CASE OF ACUTE IRIDOCYCLITIS

3. Intercalary staphyloma

4. Equatorial staphyloma

CASE DESCRIPTION

5. Posterior staphyloma

Presenting symptoms. A patient with acute

iridocyclitis (anterior uveitis) presents with moderate

How is an anterior staphyloma formed?

to severe pain which radiates all over the distribution

In a patient with sloughing corneal ulcer when the

of trigeminal nerve, photophobia, watering, redness

whole cornea sloughs out, the inflamed iris is covered

and some diminution of vision of sudden onset.

with exudates. Ultimately these exudates organize and

History of present illness. In addition to the details

form a fibrous layer over which the conjunctival or

about the presenting symptoms, the history of present

corneal epithelium rapidly grows and thus a

illness should also explore the following associations:

pseudocornea is formed. Since the pseudocornea is

History of allergic conditions like bronchial asthma,

thin and cannot withstand the intraocular pressure, it

hay fever, allergic rhinitis, allergic skin conditions

usually bulges forward along with the plastered iris

History of joint pains to rule out rheumatoid

tissue. This ectatic cicatrix is called anterior

disease

staphyloma.

History suggestive of urethritis

History of any dental problem

What is the treatment of anterior staphyloma?

History of chronic rhinitis and/or sinusitis

1. Most of the times there is no chance of getting

History of trauma to eye

useful vision in such eyes. Therefore, treatment

Past history should include enquiries about:

is carried out to improve the cosmetic appearance.

History of similar attacks in the past

Localized staphylectomy under heavy doses of

History of chronic systemic infections such as

steroids may be carried out. After healing,

tuberculosis, syphilis, leprosy, measles, mumps

cosmetic artificial shell may be advised.

and any other infection

CLINICAL OPHTHALMIC CASES

511

History of non-infectious systemic disorders such

RELATED QUESTIONS

as diabetes, gout, rheumatoid arthritis and

Define uveitis

collagen disorder

Uveitis refers to inflammation of any part or whole of

History of allergic and autoimmune disorders

the uveal tract. Uveal tract includes iris, ciliary body

General physical and systemic examination should

and choroid.

be conducted to rule out systemic diseases

How do you classify uveitis ?

enumerated in the history. Special care should be

Anatomical classification

given to dental, ENT, lymph nodes and joint

1. Anterior uveitis (iridocyclitis)

examinations.

2. Intermediate uveitis (pars planitis)

Ocular examination may reveal following signs

3. Posterior uveitis (choroiditis)

(Fig.7.8):

4. Panuveitis

Visual acuity is diminished.

II. Clinical classification

Lids may show slight oedema.

1. Acute uveitis

2. Chronic uveitis

Circumcorneal congestion is marked.

III. Pathological classification

Cornea may be slightly hazy due to oedema and

1. Suppurative or purulent uveitis

KPs at the back of cornea which are seen on slit-

2. Non-suppurative uveitis, which may be:

lamp examination.

(i) Non-granulomatous uveitis

Anterior chamber shows aqueous cells and

(ii) Granulomatous uveitis

aqueous flare,hypopyon may also be present

IV. Aetiological classssification

(Duke-Elder’s)

Iris may show loss of normal pattern, muddy

1. Infective uveitis

2. Allergic uveitis

colour, posterior synechiae, iris nodules and

3. Toxic uveitis

patches of atrophy

4. Traumatic uveitis

Pupil is narrow, irregular and sluggishly reacting.

5. Uveitis associated with non-infective

Exudates may be present in pupillary area,occlusio

systemic diseases

pupillae and seclusio pupillae may be seen in

6. Idiopathic uveitis

some cases.

What is the differential diagnosis of acute

Lens. Pigment dispersal, exudates and iris

iridocyclitis?

adhesion may be seen on anterior capsule.

Acute iridocyclitis must be differentiated from other

Complicated cataract may also occur.

causes of acute red eye; especially acute congestive

IOP may be normal, low or raised. It is raised

glaucoma and acute conjunctivitis. The differentiating

firstly in hypertensive uveitis and secondly in

features are shown in Table 7.1.

pupillary block secondary glaucoma.

What are the differences between granulomatous

and non-granulomatous uveitis?

A CASE OF CHRONIC IRIDOCYCLITIS

These are as shown in Table 7.2.

CASE DESCRIPTION

What are the common causes of acute anterior

Presenting symptoms are mild to moderate dull ache

uveitis?

in the eye, mild photophobia and diminution of vision.

1. Microbial allergy, e.g., allergy to tubercular

History of present illness and past history should

proteins, streptococcal proteins, spirochaetal

explore the diseases mentioned in a case of acute

proteins, etc.

iridocyclitis.

2. Atopic uveitis

Ocular examination may reveal mild circumcorneal

3. HLA associated uveitis, e.g., HLA-B₂₇: Anterior

flush, keratic precipitates, aqueous flare, aqueous

uveitis is associated with ankylosing spondylitis

cells, iris atrophic patches, iris nodules, posterior

and Reiter’s syndrome.

synechial neovascularization and irregular pupil.

4. Idiopathic

512

Comprehensive OPHTHALMOLOGY

What are the causes of granulomatous uveitis?

2. Posterior synechiae: These refer to adhesions of

Tuberculosis

posterior surface of iris to the anterior surface of

Syphilis

crystalline lens or intraocular lens implant or

Sarcoidosis

posterior capsule or anterior phase of the vitreous.

Leprosy

These are of the following types:

Vogt-Koyanagi-Harada’s disease

Posterior segmental synechiae (Fig.7.8)

Sympathetic ophthalmia

Annular synechiae (Fig.7.13), and

Total posterior synechiae (Fig.7.14).

What are the common causes of unilateral

iridocyclitis?

What is seclusio pupillae and iris bombe ?

Traumatic uveitis

Annular or ring synechiae are 360° adhesions of

Herpes zoster uveitis

pupillary margin to anterior capsule of the lens.

Fuchs’ heterochromic cyclitis

These prevent the circulation of aqueous humour from

Retinal detachment

posterior to anterior chamber (seclusio pupillae).

Haemophthalmitis

Thus, the aqueous collects behind the iris and pushes

Iridocyclitis secondary to intraocular tumours

it anteriorly (leading to iris bombe formation).

What are the keratic precipitates; what are their

What is occlusio pupillae?

types and significance?

Occlusio pupillae refers to occlusion of pupil by the

Keratic precipitates are proteinaceous-cellular

exudates.

deposits occurring at the back of cornea (Fig.7.9).

What is festooned pupil?

These are of the following types:

When atropine is instilled in the presence of

1. Fine KPs are characteristic of Fuchs’ cyclitis and

segmental posterior synechiae, the pupil does not

herpes zoster uveitis.

dilate in the areas of synechiae, but dilates in the

2. Small and medium size KPs are seen in acute and

areas without synechiae. This results in an irregular

chronic non-granulomatous uveitis. These are

and dilated pupil known as festooned pupil.

composed of lymphocytes and may number in

hundreds (usually 40-60).

Name the various types of HLA associated

3. Mutton fat KPs. These typically occur in

uveitis.

granulomatous iridocyclitis and are composed of

HLA-B₂₇ :

Anterior uveitis seen with

epithelioid cells and macrophages. They are large,

ankylosing spondylitis and Reiter’s

thick, fluffy, lardaceous KPs, having a greasy or

syndrome

waxy appearance. They are usually few (10-15) in

HLA-B₅ :

Behcet’s disease

number.

HLA-BW₅₄:

Glaucomatocyclitic crisis

HLA-BW₂₂:

Vogt-Koyanagi-Harada’s synd-

What are iris nodules ?

rome

Iris nodules typically occur in granulomatous uveitis.

Nodules situated at pupillary border are known as

What are the causes of diminution of vision in a

Koeppe’s nodules, while those seen near the

patient with iridocyclitis?

collarette are called Busacca’s nodules (Fig.7.12).

One or more of the following factors cause diminution

of vision:

What are synechiae; describe their types?

Corneal oedema

Synechiae are adhesions of the iris with other

Aqueous haze

intraocular structures. These can be divided into

Exudates in the pupillary area

following types:

Complicated cataract

1. Anterior synechiae: These include anterior

Cyclitic membrane

peripheral synechiae seen in the angle of anterior

Vitreous haze

chamber and anterior central synechiae seen in

Papillitis

adherent leucoma.

Macular oedema

CLINICAL OPHTHALMIC CASES

513

What are the complications of iridocyclitis?

What are the features of glaucomatocyclitic crisis

(Posner-Schlossman syndrome) ?

Complicated cataract (Fig.7.15)

Secondary glaucoma

It typically affects young adults and is characterized

by:

Cyclitic membrane

Recurrent attacks of acute rise of IOP (40-50 mm

Cystoid macular oedema

of Hg) without shallowing of anterior chamber

Secondary periphlebitis retinae

Fine KPs at the back of cornea without any

Band-shaped keratopathy

posterior synechiae

Phthisis bulbi

Epithelial corneal oedema

What is the treatment of iridocyclitis?

A dilated pupil

I. Non-specific treatment

A white eye (no congestion)

a) Local therapy

What is sympathetic ophthalmitis ?

1. Mydriatic-cycloplegic drugs, e.g.,

1 percent

Sympathetic ophthalmitis is rare bilateral

atropine, eyedrops or ointment; or percent

granulomatous panuveitis which occurs following

homatropine eyedrops

penetrating ocular trauma usually associated with

2. Corticosteroid

eyedrops

such

incarceration of uveal tissue in the wound. The

dexamethasone eyedrops 4 times a day

injured eye is called exciting eye and the fellow eye

b) Systemic therapy

which also develops uveitis is called sympathizing

1. Corticosteroids are quite useful in severe cases.

eye.

2. Non-steroidal anti-inflammatory drugs

(NSAIDs) such as aspirin and phenylbutazone

What are Dalen-Fuchs’ nodules?

are used when steroids are contraindicated.

Dalen-Fuchs’ nodules are proliferation of the pigment

3. Immunosuppressive drugs are used in

epithelium of iris and ciliary body to form nodular

desperate and extremely serious cases.

aggregations in sympathetic ophthalmitis.

4. Adrenocorticotropic hormone (ACTH) may be

What is Behcet’s disease ?

required in recalcitrant cases.

Behcet’s disease is an idiopathic multisystem disease

c) Physical measures

associated with HLA-B₅. It is characterized by:

1. Hot fomentation. It is very soothing, diminishes

Recurrent acute iridocyclitis associated with

pain and increases circulation.

hypopyon

2. Dark goggles give feeling of comfort by

Aphthous ulceration

reducing photophobia.

Genital ulceration

II. Specific treatment

Erythema multiforme

It consists of treatment of the cause when discovered,

e.g., antitubercular drugs for the underlying Koch’s

What are ocular lesions of sarcoidosis ?

disease, adequate treatment of associated syphilis,

1. Sarcoid plaque on the skin of the eyelids

toxoplasmosis, etc.

2. Granulomatous infiltration of the lacrimal gland

with xerosis

What are the features of Fuchs’ uveitis?

3. Conjunctival sarcoid nodules

Fuchs’ uveitis is a chronic non-granulomatous type

4. Episcleritis

of low-grade anterior uveitis. It is unilateral and affects

5. Iridocyclitis may occur as:

middle-aged persons. The disease is characterized

Acute iridocyclitis

by:

Chronic granulomatous iridocyclitis

(more

Heterochromia of iris

common) with Koeppe’s and Busacca’s

Fine KPs at the back of cornea

nodules on the iris and mutton fat KPs

Faint aqueous flare

Uveoparotid fever (Heerfordt’s syndrome)

Absence of posterior synechiae

6. Vitritis with snowball opacities

A fairly common rubeosis iridis

7. Choroidal and retinal granulomas

Comparatively early development of complicated

8. Secondary periphlebitis retinae with candle wax

cataract and secondary glaucoma

droppings

514

Comprehensive OPHTHALMOLOGY

What is VKH Syndrome ?

Metamorphopsia

(patient perceives distorted

Vogt-Koyanagi-Harada’s (VKH) syndrome is an

images of the objects) results due to alteration in

idiopathic multisystem disorder associated with HLA-

the retinal contour caused by a raised patch of

BW22. It is characterized by:

choroiditis

Cutaneous lesions such as: alopecia, poliosis

Macropsia, i.e., perception of the objects larger

and vitiligo

than they are, may occur due to crowding together

Neurological lesions include meningism,

of cones

encephalopathy, tinnitus, vertigo and deafness

Photopsia, i.e., a subjective sensation of flashes

Ocular features are: chronic granulomatous

of light may result due to irritation of cones by

anterior uveitis, posterior uveitis and exudative

inflammatory oedema.

retinal detachment.

What is the most common cause of central

What is endophthalmitis? Enumerate common

choroiditis?

causes of purulent endophthalmitis.

Toxoplasmosis.

Endophthalmitis is inflammation of the inner

What is pathognomonic feature of fungal endopht-

structures of the eyeball which include uveal tissue,

halmitis?

retina and vitreous. Purulent endophthalmitis is a

dreaded complication. Its common causes are:

Flufy ball opacities in the vitreous are pathognomonic

1. Exogenous infections following:

of fungal endophthalmitis.

Perforating injuries

At what stage vitrectomy operation should be

Perforation of corneal ulcer

performed in a patient with endophthalmitis?

Intraocular operations such as cataract surgery

Vitrectomy is the treatment of choice for fungal

and glaucoma surgery

endophthalmitis. In bacterial endophthalmitis it

2. Endogenous or metastatic endophthalmitis may

should be performed when the condition does not

occur rarely through blood stream from some

improve with intensive conservative therapy for 48

septic focus in the body such as caries teeth,

hours.

puerperal sepsis and generalized speticaemia.

What is Reiter’s syndrome ?

What is panophthalmitis? Describe its treatment.

Reiter’s syndrome is characterized by a triad of

Panophthalmitis is an intense purulent inflammation

urethritis, arthritis and conjunctivitis. In 20 to 30 per

of the whole eyeball including the Tenon’s capsule.

cent cases, acute non-granulomatous uveitis is also

Since there is little hope of saving such an eye,

associated.

evisceration operation should be performed to remove

the pus and infected intraocular contents leaving

What are the causes of a patch of iris atrophy?

behind the sclera.

Senile

Post-inflammatory

Which is the most common presenting symptom

in a patient with choroiditis ?

Glaucomatous

Neurogenic, in lesions of ciliary ganglion

Floaters, i.e., moving small black spots in front of the

Essential iris atrophy

eyes is the most common presenting symptom in a

patient with choroiditis. Floaters occur due to pouring

of exudates in the vitreous.

DISEASES OF THE LENS

What are the symptoms of central choroiditis?

A CASE OF SENILE CATARACT

Defective vision

CASE DESCRIPTION

Floaters

Micropsia (patient complains of seeing the objects

Age and sex. It is seen equally in persons of either

smaller than normal) due to separation of cones

sex, usually above the age of 45 years (average 50-60

of macula due to oedema)

years).

CLINICAL OPHTHALMIC CASES

515

Presenting symptoms. Patient usually presents with

2. Acquired cataract

a gradual, painless and progressive loss of vision. In

1. Senile cataract

the early stages there may or may not be associated

2. Traumatic cataract

history of coloured haloes, uniocular polyopia, glare

3. Complicated cataract

and misty vision.

4. Metabolic cataract

History of present illness. In addition to the details

5. Electric cataract

about the presenting symptoms, the history of present

6. Radiational cataract

illness should be taken:

7. Toxic cataract, e.g.,

To rule out other cause of acquired cataract

a) Corticosteroid-induced cataract

e.g., history of exposure to radiations (radiation

b) Miotics-induced cataract

cataract) excessive heat in industrial workers

c) Copper-and iron-induced cataracts (in

especially in glass workers and iron workers

chalcosis and siderosis respectively)

(heat cataract), history of injury to the affected

8. Cataract associated with skin diseases

eye

(traumatic cataract), history of diabetes

(dermatogenic cataract)

mellitus

(diabetic cataract), history of atopic

9. Cataract associated with osseous diseases

diseases (atopic cataract),history of steroid intake

10. Cataract associated with miscellaneous

(steroid cataract), history suggestive of anterior

syndromes e.g.,

uveitis (complicated cataract) etc.

Dystrophia myotonica

To rule out diseases affecting surgical treatment

Down’s syndrome

such as history of hypertension, diabetes mellitus,

II. Morphological classification (Fig.8.4)

bronchial asthma.

1. Capsular cataract: It involves the capsule and

Ocular signs observed in different types of senile

may be:

cataract are shown in Table 8.1, page 179

a) Anterior capsular cataract

General physical and systemic examination (see

page 183)

b) Posterior capsular cataract

Ocular examination. In addition to ocular

2. Cortical cataract: It involves the cortex of the

examination to note signs of different types of

lens

cataract, the following useful information is essential

3. Nuclear cataract: It involves the nucleus of the

before the patient is considered for surgery (see page

crystalline lens

183):

4. Polar cataract: It involves the capsule and

Retinal function tests,

superficial part of the cortex in the polar region

Search for local source of infection,

and may be:

Slit-lamp examination for anterior segment status,

a) Anterior polar cataract

and

b) Posterior polar cataract

IOP measurement.

What are the types of senile cataract ?

RELATED QUESTIONS

Cortical cataract

Nuclear cataract

What is your diagnosis?

Senile cataract (immature, mature, hypermature or

Name the stages of maturation of senile cortical

nuclear, depending upon the type of cataract).

cataract.

Define cataract.

Stage of lamellar separation

Stage of incipient cataract

Normal crystalline lens is a transparent structure. Any

Stage of immature senile cataract (cuneiform or

opacity in the lens or its capsule is called a cataract.

cupuliform)

How do you classify cataracts ?

Stage of mature senile cataract

I. Aetiological classification

Stage of hypermature senile cataract (Morgagnian

1. Congenital and developmental cataract

or sclerotic type)

516

Comprehensive OPHTHALMOLOGY

What do you mean by nuclear sclerosis?

What preoperative evaluation would you like to

Nuclear siderosis is an aging process in which lens

carry out before cataract surgery ?

nucleus becomes inelastic and hard. Refractive index

1. General physical and systemic examination to

of the lens is increased resulting in myopia. These

rule out: diabetes mellitus, hypertension,

changes begin centrally and spread peripherally. On

obstructive lung disorders and any potential

oblique illumination pupillary area looks greyish.

source of infection in the body such as septic

gums, urinary tract infection, etc.

How will you differentiate immature senile

2. Ocular examination with special reference to:

cataract (ISC) from nuclear sclerosis without

cataract changes?

1. Retinal function tests

2. Search for local source of infection, i.e.,

See Table 8.3, Page 180

conjunctivitis, dacryocystitis, blepharitis, etc.

Name the complications which can occur during

3. Intraocular pressure measurement.

maturation of cortical cataract.

(a) Lens-induced glaucoma, which may be:

Name the retinal function tests that you would like

1. Phacomorphic glaucoma

(secondary narrow-

to carry out before planning cataract surgery?

angle glaucoma). It occurs due to intumescent

1. Light perception (PL)

(swollen) lens causing blockage of the angle of

2. Projection of light rays (PR)

anterior chamber and pupil

3. A test for Marcus Gunn pupillary response

2. Phacolytic glaucoma

(secondary open-angle

4. Two-light discrimination test

glaucoma). It occurs due to blockage of trabecular

meshwork by macrophages laden with lens

What is the most accurate method of predicting

the macular potential for visual acuity in the

proteins leaked from the Morgagnian hypermature

presence of advanced cataract?

cataract

Laser interferometry.

(b) Phacoanaphylaxis

Name the objective tests for evaluating posterior

segment of eye in a cataract patient.

What are the characteristics of diabetic cataract?

1. Ultrasonography (A and B scan)

A true diabetic cataract is characterized by appearance

2. Electroretinography

of bilateral snowflake-like opacities hence the name

‘snowflake cataract’ or ‘snow-storm cataract’

3. Electro-oculography

4. Visually-evoked response

What are the characteristics of a complicated

cataract?

Surgical management of adulthood cataracts

A typical complicated cataract is characterized by

For questions related to surgical management of

‘bread-crumb’ appearance of the opacities situated

cataract, see page 587

in the posterior subcapsular area, which exhibit

‘polychromatic lustre’ on slit-lamp examination.

A CASE OF CONGENITAL/

Enumerate the indications for extraction of a

DEVELOPMENTAL CATARACT

cataractous lens.

CASE DESCRIPTION

1. Grossly diminished vision hampering easy living

2. Medical indications, e.g.,

Age and sex. Congenital cataract is present since

Lens-induced glaucoma

birth. Developmental cataract may occur any time

Phacoanaphylaxis

from infancy to adolescence. It is equally common in

Patient having diabetic retinopathy or retinal

both sexes.

detachment, treatment of which is hampered

Presenting symptoms. Parents may bring the child

by the presence of lens opacities

with one or more of the following complaints:

3. Cosmetic indication. Some patients may insist for

White reflex in the pupillary area (leukocoria)

cataract extraction (even with no hope of getting

Inability of the child to see well which may be

useful vision) in order to obtain a black pupil.

noticed by the parents

CLINICAL OPHTHALMIC CASES

517

Wandering movements of the eyes

Enumerate the aetiological factors associated

Deviation (squint) in one eye

with congenital cataract.

Nystagmus

1. Heredity (about 3 per cent cases)

History of present illness should include:

2. Maternal factors, e.g.,

Details about the time of appearance and progress

Malnutrition during pregnancy

of the above symptoms

Rubella infection

Obstetrical history to explore occurrence of

Toxoplasmosis

rubella, malnutrition, diabetes mellitus, exposure

Cytomegalo inclusion disease

to radiations and drug intake during pregnancy.

Drug ingestion during pregnancy, e.g.,

Birth history should include information about:

thalidomide, corticosteroids

home or hospital delivery; full-term or premature

3. Fetal or infantile factors, e.g.,

birth; normal or low birth weight (LBW) for age;

Anoxia due to placental haemorrhage

history of birth trauma; and history of ocular

Metabolic disorders, e.g., galactosaemia,

infections after birth

neonatal hypoglycaemia

Family history should include history of similar

Lowe’s syndrome

complaints in the family, history of any other

Myotonia dystrophica

ocular or systemic defects in the family, history

Birth trauma

of diabetes mellitus and history of consangui-

Malnutrition in early infancy

nous marriage.

4. Idiopathic (about 50 per cent cases)

General physical and systemic examination should

be carried out thoroughly with special attention for

What are the features of zonular (lamellar)

any associated mental retardation, cerebral palsies,

cataract?

features of rubella, features of galactosaemia,

Zonular cataract typically occurs in a zone of fetal

hepatosplenomegaly and cardiovascular anomalies

nucleus surrounding the embryonic nucleus (Fig. 8.5).

such as patent ductus arteriosus (PDA), ventricular

The area of the lens internal and external to the zone

septal defect (VSD) and pulmonary stenosis (PS).

of cataract is clear, except for small linear opacities

Ocular examination. Conspicuous sign is leukocoria

like spokes of a wheel (riders) which run outwards

(white reflex in pupillary area). Make special note of

towards the equator. It is usually bilateral and

visual acuity (if possible), any associated squint,

frequently causes severe visual defect.

nystagmus and other congenital anomalies such as

microphthalmos, microcornea, aniridia, iris coloboma,

What is the differential diagnosis of a white

and persistent pupillary membrane. Lens should be

pupillary reflex?

examined in detail after dilation of the pupil. If possible

1. Congenital cataract

fundus should be examined to know the status of the

2. Retinoblastoma

posterior segment.

3. Retinopathy of prematurity (retrolental fibroplasia)

4. Persistent hyperplastic primary vitreous

RELATED QUESTIONS

5. Parasitic endophthalmitis

Name the types of congenital cataract.

6. Exudative retinopathy of Coats

Cataracta centralis pulverulenta

(embryonic

How will you manage a case of congenital

nuclear cataract)

cataract?

Lamellar (zonular) cataract

1. Small stationary lens opacities which do not

Sutural cataract

interfere with vision can safely be ignored

Anterior polar cataract

2. Incomplete central stationary cataracts may be

Posterior polar cataract

treated by optical iridectomy or use of mydriatics

Coronary cataract

to improve the vision considerably

Blue dot punctate cataract

3. Complete cataracts should be removed surgically

Total congenital cataract

as early as possible

518

Comprehensive OPHTHALMOLOGY

Name the surgical procedures in vogue for

A CASE OF PSEUDOPHAKIA

management of childhood cataracts

CASE DESCRIPTION

1. Discission (needling) operation (almost obsolete)

Presenting symptoms

2. Anterior capsulotomy and irrigation aspiration of

the lens matter

Patient usually gives a history of cataract

operation and may also be aware of the intraocular

3. Lensectomy

lens (IOL) implantation.

How should paediatric aphakia be corrected?

Patient may give history of normal far vision

1. Children above the age of 5 years can be corrected

(emmetropia produced by IOL) but defective near

by implantation of posterior chamber intraocular

vision due to loss of accommodation.

Some patients may give history of normal near

lens during surgery

vision but defective far vision

(due to 2-3 D

2. Those below the age of 5 years should preferably

myopia produced by a high power IOL).

be treated by extended wear contact lens.

Some patients are uncomfortable due to defective

Spectacles can be prescribed in bilateral cases.

vision both for distance and near. This occurs

At a later stage secondary IOL implantation may

due to hypermetropia produced by a low power

be considered

IOL and loss of accommodation.

3. Epikeratophakia and keratophakia are still under

trial

Signs of pseudophakia

Surgical limbal scar may be seen

A CASE OF APHAKIA

Anterior chamber is slightly deeper than normal

When implanted, the angle supported anterior

CASE DESCRIPTION

chamber IOL (Fig.8.23) and iris claw IOL (Fig.8.25)

Presenting symptoms. Patient usually gives history

are seen in the anterior chamber.

of cataract extraction operation (postoperative

Mild iridodonesis (tremulousness of iris) may be

aphakia). Sometimes patient may present with such a

demonstrated

situation following trauma to the eye (aphakia due to

Purkinge image test shows four images

traumatic posterior dislocation of lens) and rarely

Pupil is blackish in colour. When light is thrown

without any cause (aphakia due to spontaneous

in pupillary area, shining reflexes are observed.

posterior dislocation of lens).

When examined under magnification after dilating

the pupil, the presence of posterior chamber IOL

Patient usually has marked loss of vision both for

when implanted is confirmed (Fig.8.26)

distance and near due to high hypermetropia and

Visual status and refraction of the patient will

absence of accommodation, respectively.

vary depending upon the power of IOL implanted

Patient may complain of seeing red (erythropsia)

as described above.

and blue (cyanopsia) images. This occurs due to

excessive entering of ultraviolet and infra red

RELATED QUESTIONS

rays in the absence of crystalline lens.

Define aphakia

Signs of aphakia seen on ocular examination:

Aphakia literally means absence of the crystalline lens

Limbal scar may be seen in surgical aphakia

from the eye. However, from the optical point of view,

Anterior chamber is deeper than normal

it may be considered as a condition in which the lens

Iridodonesis, i.e., tremulousness of the iris can

is absent from the pupillary area and does not take

be demonstrated

part in refraction. Optically aphakia may be:

Pupil is jet black in colour

Complete aphakia i.e, whole of the lens is absent

Purkinge image test shows only two images

from its normal position.

(normally four images are seen)

Partial aphakia, i.e., part of the lens is present

Fundus examination shows hypermetropic small

in the pupillary area. In this situation aphakic and

disc

phakic portions are seen simultaneously in

Retinoscopy reveals high hypermetropia

pupillary area.

CLINICAL OPHTHALMIC CASES

519

Enumerate the refractive changes which occur in

What are fundus findings in a patient with high

an aphakic eye.

hypermetropia?

1. Eye becomes highly hypermetropic.

Fundus examination in a patient with high

2. Total power of the eye is reduced to +44 DS from

hypermetropia may show:

+60 DS.

Pseudopapillitis

3. Anterior focal distance becomes 23 mm (from 15

Shot silk appearance of the retina

mm in normal phakic eye).

Enumerate the signs of aphakia.

4. Posterior focal distance becomes 31 mm (from 24

Deep anterior chamber

mm in normal phakic eye).

Iridodonesis

5. There is anterior shift of nodal point and principal

Jet black pupil

focus.

Purkinje’s image test shows only two images

6. There is complete loss of accommodation due to

(normally four)

absence of lens.

Fundus examination shows small optic disc.

7. Astigmatism is induced due to corneal/limbal

Retinoscopy, reveals high hypermetropia.

scar.

What is the average standard power of the lenses

Name the various modalities for correction of

required for spectacle correction of aphakia ?

aphakia and enumerate advantages and

In preoperative emmetropic patient, the standard

disadvantages of each.

power of the lenses required for spectacle correction

1. Spectacles

of aphakia for distance vision is + IODS with an

Advantages: It is cheap, easy and safe method of

additional cylindrical lens for acquired astigmatism.

correcting aphakia.

For near vision correction an additional +3DS is

Disadvantages: (i) Image is magnified by 30 per cent,

required as the accommodation is absent in an aphakic

so not useful in unilateral aphakia (produces

eye.

diplopia), (ii) problems of spherical and chromatic

aberrations may be troublesome, (iii) field of vision is

What is pseudophakia?

limited, (iv) prismatic effect of thick glasses causes,

Pseudophakia refers to presence of an intraocular lens

‘roving ring scotoma’ (v) cosmetic blemish, especially

in the pupillary area.

in young aphakics.

What is the refractive position of the pseudophakic

2. Contact lenses

eye ?

Advantages: (i) Less magnification (5%) of the image,

(ii) elimination of aberrations and prismatic effect of

A pseudophakic eye may be emmetropic, myopic or

thick glasses, (iii) wider and better field of vision, (iv)

hypermetropic depending upon the power of the IOL

cosmetically better accepted by young persons.

implanted.

Disadvantages: (i) more cost, (ii) cumbersome to wear,

What is the average standard power of the

especially in old age and in childhood, (iii) corneal

posterior chamber IOL ?

complications may occur.

Exact power of an IOL to be implanted varies from

3. Intraocular lens implantation

individual to individual and is calculated by biometry

It is the best available method of treatment.

using keratometer and A-scan ultrasound.

Advantage: It offers all the advantages which the

contact lenses offer over the spectacles. In addition,

What is the average weight of an IOL?

the disadvantages of contact lenses are also taken

Average weight of an IOL in air is 15 mg and in aqueous

care of.

humour is about 5 mg.

Disadvantages: It requires more skilled surgeons and

costly equipment.

What is the power of the IOL in air vis-a-vis in the

aqueous humour?

4. Refractive corneal surgery

It is still under trial and includes keratophakia and

Power of an IOL in air is much more (about +60D)

epikeratophakia.

than that in the aqueous humour (about + 20D).

520

Comprehensive OPHTHALMOLOGY

What is the difference in the power of an anterior

4. Chronic congestive glaucoma. Patients have dull

chamber IOL versus posterior chamber IOL ?

and constant pain in the eye along with marked

Equivalent power of an anterior chamber IOL is less

diminution of vision. Patients usually give history of

(say about +18D) than that of posterior chamber IOL

preceding attack of acute congestive glaucoma or

(+20D).

repeated attacks of intermittent glaucoma.

5. Absolute glaucoma. Such patients present with:

Surgical management of cataract

Pain in the eye which is severe and irritating

For questions related to surgical management of a

Constant headache

cataract patient, see page 587.

Watering and redness of the eye

Complete loss of vision

(no perception of

light)

GLAUCOMA

This stage results if the chronic phase is left

untreated.

Ocular examination. The signs observed on ocular

A CASE OF PRIMARY NARROW ANGLE

examination depend upon the stage of glaucoma (See

GLAUCOMA

page 225-231):

CASE DESCRIPTION

1. Latent glaucoma (prodromal stage). The eye is

white and quiet. Anterior chamber is shallow.

Age and sex. Primary narrow-angle glaucoma usually

Gonioscopy reveals narrow angle. IOP is usually

presents between 50 and 60 years of age. It occurs

normal.

more commonly in females than males in a ratio of 4:1.

2. Intermittent glaucoma (subacute glaucoma).

Presenting symptoms depend upon the stage of the

Usually the patient presents after the attack is over

disease as follows:

and eye looks normal except for a shallow anterior

1. Latent glaucoma (Primary angle-closure glaucoma

chamber and narrow angle (on gonioscopy)

suspect). Patient does not present in this stage as

3. Acute congestive glaucoma. Signs are as follows:

there are no symptoms. Latent primary angle-closure

Lids may be oedematous

glaucoma is diagnosed:

Conjunctiva is chemosed, and congested,

On routine slit-lamp examination in patients

(both conjunctival and ciliary vessels are

presenting with some other eye disease, and

congested).

In fellow eye of the patients presenting with

Cornea becomes oedematous and insensitive.

subacute or acute angle-closure glaucoma.

Anterior chamber is very shallow. Aqueous

2. Intermittent glaucoma (Subacute glaucoma).

flare or cells may be seen in anterior chamber.

Patient presents with transient blurring of vision,

Angle of anterior chamber is completely closed

coloured haloes around the light due to corneal

as seen on gonioscopy.

oedema and mild headache. These symptoms are due

Iris may be discolored.

to transient rise in intraocular pressure (IOP) and occur

Pupil is semidilated, vertically oval and fixed.

in intermittent attacks at irregular intervals. The

It is non-reactive to both light and accommo-

attacks are usually precipitated by overwork in the

dation.

evening, anxiety and fatigue.

IOP is markedly elevated, usually between 40

3. Acute congestive glaucoma (acute angle- closure

and 70 mm of Hg.

glaucoma). Patient presents with an attack of sudden

Optic disc is oedematous and hyperaemic.

onset of very severe pain in the eye which radiates

Fellow eye shows shallow anterior chamber

along the branches of fifth nerve. Frequently there is

and a narrow angle.

history of associated nausea, vomiting and

4. Chronic closed-angle glaucoma. Signs are as

prostrations. There is history of rapidly progressive

follows:

loss of vision, redness, photophobia and watering.

The IOP remains constantly raised.

About 5 per cent patients give history of typical

The eye remains permanently congested and

previous intermittent attacks.

irritable, except in cases where chronic closed

CLINICAL OPHTHALMIC CASES

521

angle glaucoma results due to gradual creeping

Occasionally an observant patient may notice a

synechial angle closure. (In such cases, eye is

defect in the visual field (scotoma).

painless and white like primary open-angle

In late stages patient may complain of delayed

glaucoma).

dark adaptation.

Visual field defects appear which are similar to

Ocular examination. Anterior segment is usually

those in POAG.

normal. In advanced cases the pupils are sluggishly

Optic disc may show glaucomatous cupping

reacting. Fixed and dilated pupils are seen in absolute

(Pl.III.5).

glaucoma. Diagnosis is usually made from triad of

Visual acuity is decreased.

raised intraocular pressure (IOP), glaucomatous optic

Gonioscopy reveals angle closed by peripheral

disc changes and visual field changes (see pages

anterior synechiae.

215-220) In a case of POAG operated for

Absolute glaucoma. Signs are as follows:

trabeculectomy, a filteration conjunctival bleb is seen

Lids show mild oedema.

at the site of operation near the limbus.

Palpebral aperture is slightly narrow.

The anterior ciliary veins are dilated with a

A CASE OF PHACOMORPHIC GLAUCOMA

slight ciliary flush around the cornea

Presenting symptoms. Patient presents with a sudden

(perilimbal reddish blue zone).

onset of severe pain, redness, watering from the eyes

In long-standing cases, few prominent and

and marked loss of vision. Usually there is associated

enlarged vessels are seen in the form of ‘caput

nausea, vomiting, headache and prostration. Patient

medusae’.

always gives history of preceding gradual painless

Cornea in early cases is clear but insensitive.

loss of vision.

Slowly it becomes hazy and may develop

Ocular examination reveals following signs

epithelial bullae

(bullous keratopathy) or

(Fig.9.20):

filaments (filamentary keratitis).

Lids may be oedematous.

Anterior chamber is very shallow.

Conjunctiva is chemosed and congested (both

Iris becomes atrophic.

conjunctival and ciliary vessels are congested).

Pupil becomes fixed and dilated and gives a

Cornea becomes oedematous and insensitive.

greenish hue.

Anterior chamber is very shallow (opposite eye

Optic disc shows glaucomatous optic atrophy.

normal). Aqueous flare and cells may be seen in

Intraocular pressure is high; eyeball becomes

the anterior chamber

stony hard.

Pupil is semidilated, vertically oval and fixed.

Lens is cataractous, swollen and bulging forward

A CASE OF PRIMARY OPEN-ANGLE

(intumescent cataract).

GLAUCOMA

IOP is markedly elevated.

CASE DESCRIPTION

A CASE OF PHACOLYTIC GLAUCOMA

An early case of primary open-angle glaucoma

(POAG) is usually not given in undergraduate

CASE DESCRIPTION

examinations. However, an advanced or a case of

The presenting symptoms and signs are similar to

POAG which has been operated for trabeculectomy

phacomorphic glaucoma except for following

may be kept as short or long case.

differences:

Age and sex. POAG usually affects about 1 in 100 of

Anterior chamber is not shallow. It is normal or

the general population (of either sex) above the age

slightly deep. Aqueous is turbid.

of 40 years. The disease is essentially bilateral.

Lens shows hypermature Morgagnian senile

Presenting symptoms. The disease is insidious and

cataract.

usually asymptomatic. Mild symptoms experienced

by the patients include:

RELATED QUESTIONS

Mild headache and eyeache.

What are normal values of intraocular pressure?

Difficulty in reading (patients usually give history

Range: 10 to 21 mm of Hg

of frequent change in near vision glasses).

Mean: 16 ± 2.5 mm of Hg

522

Comprehensive OPHTHALMOLOGY

What is the normal amount of aqueous humour

Name the precipitating factors for an attack of

present in the eye ?

acute congestive glaucoma.

Normal amount of aqueous humour present in the

Dim illumination

Emotional stress, anxiety and excitement

anterior chamber is about 0.25 ml and in posterior

Use of mydriatics

chamber is 0.06 ml.

Describe the mechanism of rise in IOP in acute

What is the normal rate of aqueous production?

narrow-angle glaucoma.

2.3 µl/minute.

Mid-dilated pupil — increased contact between the

lens and relative iris pupil block - physiological iris

What is the site of aqueous production?

bombe formation — appositional angle closure

Ciliary processes.

(causing transient rise in IOP) — synechial angle

closure — prolonged rise in IOP.

Name the mechanisms concerned with aqueous

production?

Name the clinical stages of primary angle-closure

glaucoma.

Diffusion

1. Latent primary angle-closure glaucoma

Ultrafiltration

2. Intermittent or subacute glaucoma.

Active secretion

3. Acute angle-closure (acute congestive) glaucoma

4. Chronic angle-closure glaucoma

Define glaucoma.

5. Absolute glaucoma.

Glaucoma is not a single disease but a group of

disorders in which intraocular pressure is sufficiently

Name the provocative tests used in latent or

subacute glaucoma stage to confirm the

raised (above the tolerance limit of the affected eye)

diagnosis.

to impair normal functioning of the optic nerve.

1. Darkroom test

2. Prone test

How do you classify glaucoma?

3. Prone darkroom test

Congenital/developmental glaucomas

4. Mydriatic test (10% phenylephrine test)

1. Primary congenital glaucoma

(without

5. Mydriatic-miotic test

(10% phenylephrine and

associated anomalies)

2% pilocarpine test)

2. Developmental glaucoma with other

Enumerate the sequelae of an attack of acute

associated anomalies

narrow-angle glaucoma.

II. Primary glaucoma

Sectoral iris atrophy

1. Primary open-angle glaucoma (POAG)

Spiralling of iris fibres

2. Primary angle-closure glaucoma (PACG)

Iris hole (pseudopolycoria)

3. Primary mixed mechanism glaucoma

Large irregular pupil

III. Secondary glaucomas

Glaucomflecken

Peripheral anterior synechiae

What is the incidence of primary angle-closure

Chronic corneal oedema

glaucoma ?

How will you treat a case of acute narrow angle

1 in 1000 people over 40 years

glaucoma?

Male to female ratio is 1:4

I. Immediate medical treatment to control pain and

Name the predisposing factors for PACG.

lower the intraocular pressure

1. Injectable analgesic to relieve the severe pain

Hypermetropic eyes

2. Acetazolamide 500 mg stat and then 250 mg

Small corneal diameter

qId orally.

Relative large size of the crystalline lens

3. Hyperosmotic agents, e.g., glycerol 1to 2 g per

Short axial length of eyeball

kg body weight orally in lemon juice and/or

Shallow anterior chamber

mannitol 1to 2g per kg body weight (20%

Plateau iris configuration

solution) IV over 30 minutes

CLINICAL OPHTHALMIC CASES

523

4. Pilocarpine eyedrops 2 to 4 per cent every 15

Grade 0 (Closed angle)

minutes for one hour and then qId

Angle width is 0°

5. 0.5 per cent timolol maleate eyedrops bd

None of the angle structures are seen

6. Topical steroid 3 to 4 times a day to control

(iridocorneal contact)

the inflammation

Completely closed angle

II. Surgical treatment

Name the structures forming aqueous outflow

1. Peripheral iridectomy/laser iridotomy is

system.

sufficient when peripheral anterior synechiae

1. Trabecular meshwork

(PAS) are formed in less than 50 percent of the

2. Schlemm’s canal

angle.

3. Collector channels

2. Filtration surgery

(e.g., trabeculectomy) is

performed when PAS are formed in more than

What is the incidence of primary congenital/

50 percent of the angle

developmental glaucoma?

3. Peripheral iridectomy/laser iridotomy should

Affects 1 in 10,000 live births

also be considered as prophylaxis for the

Male to female ratio is 3:1.

fellow eye.

What is the pathogenesis of developmental

Name the structures forming angle of the anterior

glaucoma?

chamber.

Failure in the absorption of mesodermal tissue

1. Root of the iris

resulting in failure of development of the angle

2. Anterior most part of the ciliary body

structures.

3. Scleral spur

What are gonioscopic findings of developmental

4. Trabecular meshwork

glaucoma ?

5. Schwalbe’s line (prominent end of Descemet’s

Barkan’s membrane may be present

membrane of cornea).

Thickening of trabecular meshwork

How will you grade the angle width

Insertion of iris above the scleral spur

gonioscopically?

Peripheral iris stroma hypoplasia

Shaffer’s grading system is as follows:

What is buphthalmous ?

Grade 4 (Wide open angle)

This term is used when eyeball enlarges (corneal

Angle width is 35°-45º

diameter becomes more than 13 mm) in children

Structures seen are from Schwalbe’s line to

developing congenital glaucoma at an early age

ciliary body

(before the age of 3 years).

Closure impossible

Grade 3 (Open angle)

What is the treatment of primary congenital

Angle width is 20°-35°

glaucoma?

Structures seen are from Schwalbe’s line to

1. Goniotomy

scleral spur

2. Trabeculotomy

Closure impossible

3. Trabeculectomy (with antifibrosis treatment)

Grade 2 (Moderately narrow angle)

Angle width is about 20°

What are the causes of secondary congenital

Structures seen are from Schwalbe’s line to

glaucoma?

trabecular meshwork

Glaucoma associated with mesodermal

Angle closure is possible but unlikely

dysgenesis of the anterior ocular segment, e.g.:

Grade 1 (Very narrow angle)

1. Posterior embryotoxon

Angle width is about 10°

2. Axenfeld’s anomaly

Structure seen is Schwalbe’s line only

3. Rieger’s syndrome

High-angle closure risk

4. Peter’s anomaly

524

Comprehensive OPHTHALMOLOGY

II. Glaucoma associated with aniridia (50%)

What is low-tension glaucoma (LTG)?

III. Glaucoma associated with ectopia lentis

This term is used when typical glaucomatous disc

syndrome

cupping with or without visual field changes is

1. Marfan’s syndrome

associated with an IOP constantly below 21 mm of

2. Weill-Marchesani’s syndrome

Hg.

3. Homocystinuria

What are the other ocular associations of POAG?

IV. Glaucoma associated with phacomatoses:

1. High myopia

1. Sturge-Weber syndrome (50% cases)

2. Fuchs’ dystrophy

2. Von Recklinghausen’s neurofibromatosis

3. Retinitis pigmentosa

(25% cases)

4. Central retinal vein occlusion (CRVO)

V. Miscellaneous conditions

5. Primary retinal detachment

1. Lowe’s syndrome (50% cases)

What are glaucomatous field defects ?

2. Naevus of Ota

3. Nanophthalmos

1. Baring of the blind spot

4. Congenital microcornea (60%)

2. Paracentral scotoma in Bjerrum’s area (an arcuate

area extending above and below the blind spot to

5. Congenital rubella syndrome (10% cases).

between 10° and 20° of fixation point)

What is the incidence of primary open-angle

3. Seidel scotoma

glaucoma?

4. Arcuate or Bjerrum’s scotoma

It affects 1 in 100 population (of either sex) above

5. Double arcuate scotoma

the age of 40 years.

6. Roenne’s central nasal step

It forms about one-third cases of all glaucomas.

7. Advanced field defects with tubular vision

What are the features of glaucomatous cupping

What is the treatment for primary open-angle

glaucoma?

of the disc?

1. Medical treatment: It is still the initial therapy.

These include (Fig.9.9 & 9.10) the following:

Topical timolol maleate 0.25 per cent BD which

1. Cup/disc ratio is increased (normal 0.3 to 0.4),

may be increased to 0.5 per cent BD Pilocarpine

asymmetry of more than 0.2 is suspicious

TDS 2 per cent which may be increased to 4 per

2. Notching of the rim

cent BD. was previously used as drug of second

3. Nasal shift of the vessels at disc

choice. Recently latanoprost (0.005%, OD) is being

4. Pallor area on the disc

considering the drug of first choice (provided

5. Presence of splinter haemorrhages on or near the

patients can afford to buy it. Dorzolamide (2%, 2-

disc margin

3 times/day) has replaced pilocarpine as the

second drug of choice and even as adjunct drug.

Name the predisposing factors for POAG.

If the patient does not respond to a single drug

1. Heredity (positive family history)

the two drugs can be combined. If still the IOP

2. Age (between 5th and 7th decade)

is not controlled, tablet acetazolamide 250 mg

3. High myopia

TDS may be added.

4. Diabetes mellitus

2. Argon laser trabeculoplasty: It may be

considered as an alternative to medical therapy

What is the characteristic triad of POAG?

or as an additional measure in patients not

1. Intraocular pressure more than 21 mm of Hg

responding to medical therapy alone.

2. Glaucomatous cupping of the disc

3. Surgical therapy: It is usually undertaken when

3. Glaucomatous field defects

patient does not respond to maximal medical

therapy alone or in combination with laser

What is ocular hypertension ?

trabeculoplasty. Recently it is also being

Ocular hypertension or glaucoma suspect is the term

considered as the primary line of treatment. Surgical

used when a patient has an IOP constantly more than

treatment mainly consists of filtration surgery

23 mm of Hg but no optic disc or visual field changes.

trabeculectomy.

CLINICAL OPHTHALMIC CASES

525

What are secondary glaucomas ?

It is characterized by a markedly raised intraocular

In secondary glaucomas, intraocular pressure is raised

pressure, persistent flat anterior chamber and a

due to some other primary ocular or systemic disease.

negative Seidel’s test.

Depending upon the causative primary disease,

What is differential diagnosis of acute congestive

secondary glaucomas are classified as follows:

glaucoma?

Lens-induced glaucomas

Acute conjunctivitis

Glaucomas associated with uveitis

Acute iridocyclitis

Pigmentary glaucoma

Secondary acute congestive glaucomas

Neovascular glaucoma

- Phacomorphic glaucoma

Pseudoexfoliative glaucoma

(glaucoma

capsulare)

- Phacolytic glaucoma

Glaucomas associated with intraocular

- Glaucomatocyclitic crisis

haemorrhages

What is post-inflammatory glaucoma ?

Steroid-induced glaucoma

Postinflammatory glaucoma refers to rise in

Traumatic glaucoma

intraocular pressure due to following complications

Glaucoma in aphakia

of anterior uveitis:

10. Glaucoma associated with intraocular tumours

Annular synechiae

11. Glaucomas associated with iridocorneal

endothelial (ICE) syndromes

Occlusio pupillae

12. Ciliary block glaucoma (malignant glaucoma)

Angle closure following iris bombe formation

Angle closure due to organization of the

What are lens-induced glaucomas?

inflammatory debris

1. Phacomorphic glaucoma: Herein IOP is raised

due to secondary angle closure and/or pupil

What is pigmentary glaucoma?

block by:

Pigmentary glaucoma refers to raised IOP in patients

Intumescent

(swollen) cataractous lens

with pigment dispersion syndrome. It typically affects

(Fig.9.20)

young myopic males. Its features are similar to POAG

Anterior subluxated lens

with associated pigment deposition on corneal

Spherophakia

endothelium (Krukenberg’s spindle) trabecular

2. Phacolytic glaucoma: Here in IOP is raised due

meshwork, iris, lens and zonules.

to clogging of trabecular meshwork by the

macrophages laden with the leaked lens proteins,

What is neovascular glaucoma?

usually in hypermature cataract.

Neovascular glaucoma refers to raised IOP occurring

3. Lens particle glaucoma: It occurs due to

due to formation of a neovascular membrane

blockage of trabeculae by the lens particles

involving angle of the anterior chamber. Usually,

following rupture of the lens or after ECCE.

stimulus to new vessel formation is retinal ischaemia

4. Phacoanaphylactic glaucoma: Sensitization of

as seen in diabetic retinopathy, CRVO, Eales’ disease.

eye or its fellow to lens proteins. Inflammatory

Other rare causes are chronic uveitis, intraocular

material clogs trabecular meshwork.

tumours, old retinal detachment, CRAO and

5. Phacotoxic glaucoma: Herein IOP is raised due

retinopathy of prematurity.

to lens matter induced uveitis.

What is pseudoexfoliation glaucoma ?

What is malignant glaucoma ?

Pseudoexfoliation glaucoma is a type of secondary

Malignant or ciliary block glaucoma occurs rarely as

open-angle glaucoma associated with pseudo-

a complication of any intraocular operation.

Classically, it occurs following peripheral iridectomy

exfoliation (PEX) syndrome. PES refers to amyloid

or filtration operation for primary narrow angle

like deposits on pupillary border, anterior lens

glaucoma. Its pathogenesis includes cilio-lenticular

surface, posterior surface of iris, zonules and ciliary

or ciliovitreal block.

processes.

526

Comprehensive OPHTHALMOLOGY

What is steroid-induced glaucoma?

RELATED QUESTIONS

Steroid-induced glaucoma is secondary open-angle

What is blepharitis and how do you classify it?

glaucoma having features similar to POAG. It probably

Blepharitis is a chronic inflammation of the lid margins.

occurs due to deposition of mucopolysaccharides in

It can be divided into four classical types:

the trabecular meshwork in patients using topical

1. Seborrhoeic or squamous blepharitis

steroid eyedrops. Roughtly 5 per cent of general

2. Ulcerative blepharitis

population is high steroid responder (develop marked

3. Mixed ulcerative with seborrhoeic blepharitis

rise of IOP after about 6 weeks of steroid therapy), 35

4. Posterior blepharitis or meibomitis.

per cent are moderate and 60 per cent are non-

How will you differentiate squamous blepharitis

responders.

from ulcerative blepharitis?

Enumerate the causes of glaucoma in aphakia.

1. In squamous blepharitis white dandruff-like scales

are seen at the lid margin while in ulcerative

Raised IOP due to postoperative hyphaema,

blepharitis yellow crusts are seen.

inflammation, vitreous filling the anterior chamber.

2. On removing the white scales underlying surface

Angle closure due to flat anterior chamber

is found to be hyperaemic in sqamous blepharitis.

Pupil block with or without angle closure

While in ulcerative blepharitis, small ulcers which

Undiagnosed pre-existing POAG

Steroid-induced glaucoma

bleed easily are seen on removing the crusts.

Epithelial ingrowth

3. Cilia may be glued together in ulcerative

Aphakic malignant glaucoma

blepharitis, but not so in squamous belpharitis.

What are the complications of ulcerative

blepharitis?

DISEASES OF THE EYELIDS

When not treated for a long time, the following

complications may occur:

A CASE OF BLEPHARITIS

1. Chronic conjunctivitis

CASE DESCRIPTION

2. Trichiasis

3. Madarosis (sparseness or absence of lashes)

Age and sex. Though more common in children,

4. Poliosis (greying of cilia)

blepharitis may occur at any age equally in both sexes.

5. Tylosis (thickening of lid margin)

Presenting symptoms. Patients usually complain of

6. Eversion of punctum leading to epiphora

deposits at the lid margin, associated with irritation,

7. Recurrent styes

discomfort, occasional watering and history of falling

of cilia or gluing of cilia.

How will you treat a case of squamous blepharitis?

Ocular examination may reveal signs of either

1. Scales should be removed from the lid margin

seborrhoeic or ulcerative (Fig.14.8) or mixed

with the help of lukewarm solution of 3 per cent

blepharitis.

soda-bicarb or some baby shampoo.

Signs of seborrhoeic blepharitis are: accummu-

2. Combined steroid and broad spectrum eye

lation of white dandruff-like scales on the lid

ointment should be rubbed at the lid margin twice

margin. On removing these scales underlying

daily.

surface is found to be hyperaemic (no ulcers).

3. Associated seborrhoea should be treated

Lashes fall out easily. In long standing cases lid

adequately.

margin is thickened and the sharp posterior lid

border tends to be rounded leading to epiphora.

How will you treat a case of ulcerative blepharitis?

Signs of ulcerative blepharitis. Yellow crusts are

1. Hot compresses.

seen at the root of cilia which glue them together.

2. Crusts should be removed after softening with 3

Small ulcers, which bleed easily, are seen on

percent soda bicarb.

removing the crusts. In between the crusts, the

3. Antibiotic ointment should be applied at lid margin

anterior lid margin may show dilated blood vessels

immediately after removal of crusts.

(rosettes).

CLINICAL OPHTHALMIC CASES

527

4. Antibiotic eye drops should be instilled 3 to 4

It is characterized by a localized, hard, red, tender

times a day.

swelling at the lid margin (PI.IV.I). In advanced stage,

5. Oral antibiotics such as amoxycillin, cloxacillin,

a pus point is visible at the lid margin.

erythromycin or tetracycline may be useful.

What is hordeolum internum? How will you

differentiate it from hordeolum externum?

A CASE OF CHALAZION (MEIBOMIAN CYST)

Hordeolum internum is a suppurative inflammation

CASE DESCRIPTION

of the meibomian gland associated with blockage of

Presenting symptoms. Patient usually presents with

the duct. It may occur as primary staphylococcal

a painless swelling near the lid margin. Patient may

infection of the meibomian gland or due to secondary

be concerned about the cosmetic disfigurement

infection in a chalazion (infected chalazion).

caused and may also feel mild heaviness in the lids.

Its symptoms are similar to hordeolum externum

except that pain is more intense due to the swelling

Sometimes, mild defective vision may occur due to

being deeply embedded in the dense fibrous tissue.

astigmatism caused by pressure of chalarzion on the

On examination it can be differentiated from hordeolum

cornea.

externum by the facts that in it, the point of maximum

Ocular examinations reveal a small, firm to hard, non-

tenderness and swelling is away from the lid margin

tender swelling present slightly away from the lid

and that pus usually points on the tarsal conjunctiva

margin (Fig.14.12). Overlying skin is normal and

(seen as a yellowish area on everting the lid) and not

mobile. The swelling usually points on the

on the root of cilia.

conjunctival side as red, purple or grey area seen on

everting the lid. Sometimes, the main bulk of swelling

When not treated, what complications can occur

may project on the skin side and occasionaly on the

in a case of chalazion ?

lid margin.

1. A large chalazion of the upper lid may press on

Differential diagnosis. Chalazion needs to be

the cornea and may cause blurred vision due to

differentiated from meibomian gland carcinoma,

induced astigmatism.

tuberculomata and tarsitis.

2. A large chalazion of the lower lid may rarely

cause eversion of the punctum or even ectropion

A CASE OF STYE

and epiphora.

Presenting symptoms include acute pain and swelling

3. Occasionally, a chalazion may burst on the

in the lid. Patient also experiences heaviness in the

conjunctival side forming a fungating mass of

eyelid, mild photophobia and watering.

granulation tissue.

Ocular examination during stage of cellulitis reveals

4. Due to secondary infection the chalazion may be

tender swelling, redness and oedema of the affected

converted into hordeolum internum.

lid margins (Fig.14.11). During stage of abscess

5. Calcification may occur, though very rarely.

formation a visible plus point on the lid margin in

6. Malignant change into meibomian gland

relation to the roof of affected cilia is formed.

carcinoma may be seen occasionally in elderly

Differential diagnosis. Stye (hordeolum externum

people.

should be differentiated from hordeolum internum.

How do you treat a case of chalazion?

RELATED QUESTIONS

1. Conservative treatment in the form of hot

What is a chalazion ?

fomentation, topical antibiotic eyedrops and oral

anti-inflammatory drugs may lead to self-resolution

Chalazion is also known as tarsal or meibomian cyst.

It is a chronic non-infective granulomatous inflam-

in a small, soft and recent chalazion.

mation of the meibomian gland.

2. Intralesional injection of long acting steroid

(triamcinolone) is reported to cause resolution in

What is hordeolum externum (stye) ?

about 50 per cent cases.

Hordeolum externum is an acute suppurative

3. Incision and curettage is the conventional and

inflammation of one of the Zeis’ glands.

effective treatment for chalazion.

528

Comprehensive OPHTHALMOLOGY

Describe the steps of incision and curettage of a

RELATED QUESTIONS

chalazion.

Define trichiasis.

1. Local anaesthesia is obtained by topical

Trichiasis refers to inward misdirection of cilia which

instillation of 4 percent Xylocaine drops in the

rub against the eyeball.

conjunctival sac and infiltration of the lid in the

region of chalazion with 2 per cent Xylocaine.

What are the common causes of trichiasis?

2. A chalazion clamp is applied with its fenestrated

1. Cicatrizing trachoma

side on the conjunctival side and the lid is

2. Ulcerative blepharitis

everted.

3. Healed membranous conjunctivitis

3. A vertical incision is made to avoid injury to the

4. Healed hordeolum externum

other meibomian glands.

5. Mechanical injuries

4. The contents are curetted out with the help of a

6. Burns and operative scars on the lid margin

chalazion scoop.

When not treated in time, what complications can

5. To avoid recurrence its cavity should be cauterized

occur in a case of trichiasis?

with carbolic acid.

1. Corneal abrasions

6. An antibiotic eye ointment is instilled and eye is

2. Superficial corneal opacities

padded.

3. Corneal vascularization

What is the treatment of a marginal chalazion?

4. Non-healing corneal ulceration

Destruction by diathermy is the treatment of choice

What is distichiasis?

for a marginal chalazion.

Distichiasis is condition of an extra posterior row of

cilia which occupy the position of meibomian glands.

A CASE OF TRICHIASIS AND ENTROPION

DESCRIPTION OF A CASE OF TRICHIASIS

How will you treat a case of trichiasis?

Presenting symptoms. Patients may present with a

1. Epilation: It is a temporary measure.

foreign body sensation, photophobia, irritation and

2. Electrolysis: After local infiltration anaesthesia, a

lacrimation. Sometimes patient may experience

current of 2 milliampere is passed for about 10

troublesome pain.

seconds through a fine needle inserted into the

Past history of the disease causative of trichiasis such

lash root. The loosened cilia with destroyed

follicles are then removed with the help of an

as cicatrizing trachoma, ulcerative blepharitis,

epilation forceps.

membranous conjunctivitis, mechanical injuries, burns

3. Cryoepilation: After infiltration anaesthesia, the

and operation of the lid margin may be explored.

cryoprobe (-20°C) is applied for 20 to 25 seconds

Ocular examination reveals one or more misdirected

to the external lid margin. The loosened lash is

cilia touching the eyeball (Fig.14.16). There may or

pulled with an epilation forceps.

may not be signs of the causative disease.

4. Surgical correction: It is similar to cicatricial

DESCRIPTION OF A CASE OF ENTROPION

entropion and should be employed when many

cilia are misdirected.

Presenting symptoms and past history exploration

are similar to a case of trichiasis.

Define entropion.

Ocular examination reveals inturned lid margin

Entropion refers to turning in of the lid margin.

(Fig.14.17). Depending upon the degree of inturning

the entropion can be divided into three grades. In

What are the types of entropion?

grade I entropion, only the posterior lid border is

Depending upon the cause,entropion may be of the

inrolled. Grade II entropion includes inturning up to

following types:

the intermarginal strip, while in grade III, the whole

1. Congenital entropion

lid margin including the anterior lid border is inturned.

2. Cicatricial entropion

Examination may also reveal signs of the causative

3. Spastic entropion

disease.

4. Mechanical entropion

CLINICAL OPHTHALMIC CASES

529

What are the causes of cicatricial entropion?

What is the treatment of senile ectropion?

1. Trachoma

Depending upon the severity of the ectropion,

2. Membranous conjunctivitis

following three operations are commonly performed:

3. Chemical burns

1. Medial conjunctivoplasty

4. Pemphigus

2. Horizontal shortening

5. Stevens-Johnson syndrome

3. Byron-Smith’s modified Kuhnt-Szymanowski

Name the surgical techniques employed for

operation.

correcting cicatricial entropion.

What is a symblepharon?

1. Resection of skin and muscle

Symblepharon is a condition in which lids become

2. Resection of skin, muscle and tarsus

3. Modified Burow’s operation

adherent with the eyeball. It results from healing of

4. Jaesche-Arlt’s operation

the kissing raw surfaces of the palpebral and bulbar

5. Modified Ketssey’s operation

conjunctiva.

Name the surgical techniques used to correct a

What are the common causes of symblepharon?

senile (involutional) entropion.

1. Chemical burns

1. Modified Wheeler’s operation

2. Thermal burns

2. Bick’s procedure with Reeh’s modification

3. Membranous conjunctivis

3. Weiss operation

4. Conjunctival injuries

4. Tucking of inferior lid retractors (Jones, Reeh and

5. Ocular pemphigus

Webing operation).

6. Stevens-Johnson syndrome

A CASE OF ECTROPION

What do you mean by ankyloblepharon?

CASE DESCRIPTION

Ankyloblepharon refers to the adhesions between

Presenting symptoms include watering (epiphora) and

margins of the upper and lower lids. It may be

cosmetic disfigurement. Patients may also have

congenital or may result after healing of chemical or

symptoms of associated chronic conjunctivitis which

thermal burns.

include irritation, discomfort and mild photophobia.

Ocular examination. The lid margin is outrolled (Fig.

What is blepharophimosis?

14.24). Depending upon the degree of outrolling,

In blepharophimosis vertical as well as horizontal

ectropion can be divided into three grades. In grade I

extent of the palpebral fissure is decreased.

ectropion, only the punctum is everted. In grade II

ectropion lid margin is everted and palpebral

What is lagophthalmos? Enumerate its common

conjunctiva is visible while in grade III the fornix is

causes.

also visible.

Lagophthalmos refers to the inability to voluntarily

Examination may also reveal signs of aetiological

close the eyelids. Its common causes are:

condition such as scar in cicatricial ectropion (Fig.

1. Paralysis of seventh nerve

14.25) and seventh nerve palsy in paralytic ectropion.

2. Marked proptosis

RELATED QUESTIONS

3. Cicatricial contraction of the lids

4. Following over-resection of the levator palpebrae

What is ectropion ?

superioris

Outrolling or outward turning of the lid margin is called

5. Symblepharon

ectropion.

6. Comatosed patient

What are the types of ectropion?

What is belpharospasm ?

1. Senile ectropion

2. Paralytic ectropion

Belpharospasm refers to the involuntary, sustained

3. Cicatricial ectropion

and forceful closure of the eyelids. It is of two types:

4. Spastic ectropion

essential belpharospasm and reflex blepharospasm.

530

Comprehensive OPHTHALMOLOGY

A CASE OF PTOSIS

How do you grade levator function?

Depending upon the amount of lid excursion caused

CASE DESCRIPTION

by levator muscle (Burke’s method), its function is

Age and sex. Ptosis may be congenital or acquired.

graded as follows:

Acquired ptosis may occur at any age in either sex.

Normal

15 mm

History. It should include age of onset, family history,

Good

8 mm or more

history of trauma, eye surgery, and variability in degree

of ptosis.

Fair

5-7 mm

Examination should include:

Poor

4 mm or less

1. Inspection to note:

Which test is carried out to confirm the diagnosis

True ptosis or pseudoptosis

in a patient with ptosis suspected of myasthenia

Unilateral or bilateral ptosis

gravis?

Eyelid crease and function of orbicularis

Presence of Jaw winking phenomenon

Tensilon or edrophonium test.

Associated weakness of extraocular muscles

Which test is carried out in a patient suspected of

Bell’s phenomenon

Horner’s syndrome?

2. Measurement of degree of ptosis

3. Assessment of levator function

Phenylephrine test.

4. Special investigations for acquired ptosis

Name the three basic surgical procedures for

For details see page 357

ptosis correction.

RELATED QUESTIONS

1. Fasanella - Servat operation

2. Levator resection operation

What is ptosis ?

3. Frontalis sling operation

Abnormal drooping of the upper eyelids is called

ptosis. Normally upper lid covers about upper one-

Name the common lid tumours.

sixth (2 mm) of the cornea. Therefore, in ptosis it

Benign tumours

covers more than 2 mm.

1. Simple papilloma

What are the types of ptosis?

2. Naevus

Congenital ptosis which may be:

3. Haemangioma

1. Simple congenital ptosis (not associated with

4. Neurofibroma

any other anomaly) (Fig.14.32A).

II. Precancerous conditions

2. Congenital ptosis with associated weakness

1. Solar keratosis

of the superior rectus muscle.

2. Carcinoma in-situ

3. As a part of blepharophimosis syndrome

3. Xeroderma pigmentosa

(Fig.14.32B).

4. Congenital synkinetic ptosis (Marcus Gunn

III. Malignant tumours

jaw winking ptosis).

1. Squamous-cell carcinoma

II. Acquired ptosis includes:

2. Basal-cell carcinoma

1. Neurogenic ptosis

3. Malignant melanoma

2. Myogenic ptosis

4. Sebaceous gland carcinoma

3. Aponeurotic ptosis

4. Mechanical ptosis

Which is the most common malignant tumour of

How do you grade ptosis ?

the lids?

Depending upon the amount of ptosis in mm, it is

Basal-cell carcinoma

graded as follows:

1. Mild ptosis (2 mm)

Which is the most common site for occurrence of

2. Moderate ptosis (3 mm)

basal cell carcinoma ?

3. Severe ptosis (4 mm).

Medial canthus.

CLINICAL OPHTHALMIC CASES

531

What is the structure of an eyelid ?

A swelling may be seen at the medial canthus

Each eyelid from anterior to posterior consists of the

(Fig.15.8). Milky or gelatinous mucoid fluid

following layers:

regurgitates from the lower punctum on pressing

1. Skin

the swelling (lacrimal mucocele).

2. Subcutaneous areolar tissue

Sometimes on pressing the swelling, a frank

3. Layer of striated muscle (orbicularis oculi and

purulent discharge flows from the lower punctum

levator palpebrae superioris in upper lid only)

(lacrimal pyocele).

4. Submuscular areolar tissue

Sometimes a swelling is seen at the inner canthus

5. Fibrous layer (tarsal) plate and septum orbitale

with a negative regurgitation test

(encysted

6. Layer of non-striated muscle fibres

(Muller’s

mucocele).

muscle)

7. Conjunctiva

RELATED QUESTIONS

Name the glands of the eyelids.

What are the causes of a watering eye ?

1. Meibomian glands

Watering from the eyes may occur either due to

2. Glands of Zeis

excessive lacrimation or may result from obstruction

3. Glands of Moll

to the outflow of normally secreted tears (epiphora).

4. Accessory lacrimal glands of Wolfring

The common causes of watering eye are listed at page

367.

What are the causes of pseudoproptosis.

Anophthalmos

Name the tests which you would like to carry out

to evaluate a case of watering eye.

Enophthalmos

Phthisis bulbi

1. Examination with diffuse illumination under

Atrophic bulbi

magnification to rule out causes of hyper-

Trachoma (stage of sequelae)

lacrimation and punctal causes of epiphora

Any tumour or nodule of upper lid

2. Regurgitation test for chronic dacryocystits

3. Fluorescein dye disappearance test (FDDT)

4. Lacrimal syringing test

5. Jone’s dye test I and II

DISEASES OF THE LACRIMAL

6. Dacryocystography

APPARATUS

7. Lacrimal scintillography

A CASE OF CHRONIC DACRYOCYSTITIS

What is regurgitation test ?

In regurgitation test a steady pressure with index

CASE DESCRIPTION

finger is applied over the lacrimal sac area above the

Age and sex. The disease may occur at any age and

medial palpebral ligament. Reflux of mucopurulent

in any sex. However, in general, females are much

discharge (a positive regurgitation test) indicates

more commonly affected than males and the disease

chronic dacryocystitis with obstruction at the lower

is more common between 40 and 60 years of age.

end of sac or nasolacrimal duct.

Presenting symptoms. A patient presents with a long

standing history of watering from the eyes which may

What are the causes of a negative regurgitation

test?

or may not be associated with a swelling at the inner

cathus.

Causes of a negative regurgitation test are:

Ocular examination may reveal any of the following

Normal sac (no dacryocystitis)

signs:

Wrong site of pressure

No swelling is seen at the medial canthus but

Patient might have emptied the sac just before

regurgitation test is positive, i.e., a reflux of

coming to the examiner’s chamber

mucopurulent discharge from the puncta when

Encysted mucocele

pressure is applied over the lacrimal sac area.

Internal fistula

532

Comprehensive OPHTHALMOLOGY

Name the indications of lacrimal syringing.

Its treatment, depending upon the age at which

1. Diagnostic indications:

child is brought is as follows:

Epiphora

What is the treatment of choice in adulthood

For dacryocystography

chronic dacryocystitis?

2. Therapeutic indications:

Dacryocystorhinostomy (DCR) operation is the

Congenital dacryocystitis

Early cases of chronic catarrhal dacryocystitis

operation of choice since it re-establishes the lacrimal

3. Prognostic:

drainage. When DCR is contraindictated,

After DCR operation

dacryocystectomy may be performed.

Describe the procedure and interpretations of the

What is dacryocystectomy ? Enumerate its

results of lacrimal syringing.

indications.

1. Topical anaesthesia is obtained by instilling 4 per

Dacryocystectomy is the excision of the lacrimal sac.

cent Xylocaine in the conjunctival sac

It should be performed only when DCR is

2. Lower punctum is dilated with a punctum dilator

contraindicated as in following conditions:

3. Normal saline is pushed into the lacrimal sac

1. Too young (less than 4 years) or too old (more

through the lower punctum with the help of a

than 60 years) a patient

syringe and lacrimal cannula (Fig.

3.7-2) and

2. Markedly shrunken and fibrosed sac

results are interpreted as follows:

3. Tuberculosis, syphilis, leprosy or mycotic

A free passage of saline through lacrimal

infection of the sac

passages into the nose indicates either no

4. Tumours of the sac

obstruction or partial obstruction.

5. Gross nasal diseases like atrophic rhinitis

In the presence of obstruction no fluid passes

6. An unskilled surgeon, because it is said that a

into the nose. When obstruction is in the

good ‘DCT’ is always better than a badly done

nasolacrimal duct, the sac fills with the normal

saline which refluxes from the upper punctum.

‘DCR’.

In case of lower canalicular obstruction, there

What are tears ?

will be immediate reflux of the saline through

Tears form the aqueous layer of tear film and are

the lower punctum. Under these circumstances

secreted by the accessory and main lacrimal glands.

the procedure should be repeated through the

upper punctum. A free passage of saline into

Tears mainly comprise water and small quantities of

the nose will confirm the blockage in the lower

salts such as sodium chloride, sugar, urea and

canaliculus while regurgitation back through

proteins. Therefore, it is alkaline and saltish in taste.

the same punctum will indicate block at the

It also contains antibacterial substances like

level of common canaliculus.

lysozyme, betalysin and lactoferrin.

What is dacryocystitis, how will you classify it?

What are the layers of tear film ?

Dacryocystits is inflammation of the lacrimal sac. It

Wolf described the following three layers of tear film:

can be classified as follows:

1. Mucous layer: It is the innermost and thinnest

1. Congenital dacryocystitis

layer of tear film. It consists of mucin secreted by

2. Adult dacryocystitis which may occur as:

the conjunctival goblet cells. It converts the

Chronic dacryocystitis, and

hydrophobic corneal surface into a hydrophilic

Acute dacryocystits

one.

2. Aqueous layer: It consists of tears secreted by

What is the aetiology of congenital dacryocystitis?

How will you treat it ?

the main and accessory lacrimal glands and forms

Congenital dacryocystitis follows stasis of secretions

the main bulk of the tear film.

in the lacrimal sac due to congenital blockage in the

3. Lipid or oily layer: It consists of secretions of

nasolacrimal duct (usually a membranous occlusion

the meibomian, Zeis and Moll’s glands. It prevents

at the lower end of NLD).

the overflow of tears and retards their evaporation.

CLINICAL OPHTHALMIC CASES

533

What are the functions of tear film ?

What is Schirmer 1 Test ?

1. It keeps the cornea and conjunctiva moist

Schirmer test measures the total tear secretions with

2. Provides oxygen to the corneal epithelium

the help of 5 × 35 mm strip of Whatman-42 filter paper.

3. It washes away debris and noxious irritants

Its normal values are more than 15 mm of wetting of

4. It prevents infection due to presence of

the filter paper strip in 5 minutes. Values between 5

antibacterial substances

and 10 mm are suggestive of mild to moderate

5. It facilitates movement of the lids over the globe.

keratoconjunctivitis sicca (KCS) and less than 5 mm

of severe KCS.

What is dry eye ?

Dry eye per se is not a disease entity but a symptom

What is Sjogren’s syndrome ?

complex occurring as a sequela to deficiency or

Sjogren’s syndrome is an autoimmune disease usually

abnormalities of the tear film.

occurring in women between 40 and 50 years of age.

Its main feature is an aqueous deficiency dry eye

What are the causes of dry eye ?

(KCS). It occurs in two forms:

1. Aqueous deficiency dry eye (keratoconjunctivitis

1. Primary Sjogren’s syndrome: In it, KCS is

sicca — KCS)

combined with xerostomia (dry mouth)

Congenital alacrimia

2. Secondary Sjogren’s syndrome: In it dry eye and

Sjogren’s syndrome

/or dry mouth is associated with an autoimmune

Riley-Day syndrome

disease, commonly rheumatoid arthritis.

Idiopathic hyposecretion

What is the treatment of dry eye?

2. Mucin deficiency dry eye

1. Supplementation by artificial tear solution such

Hypovitaminosis A (xerophthalmia)

as:

0.7 percent methylcellulose,

0.3 percent

Stevens-Johnson syndrome

hypromellose or 1.4 percent polyvinyl alcohol.

Trachoma

2. Preservation of existing tears by punctal

Chemical burns

occlusions with collagen implants or

electrocauterization

3. Lipid abnormalities

3. Mucolytics such as 5 percent acetylcysteine help

Chronic blepharitis

by dispersing the mucous threads.

Chronic meibomitis

4. Impaired eyelid function

Bell’s palsy

DISEASES OF THE ORBIT

Exposure keratitis

Ectropion

A CASE OF PROPTOSIS

5. Epitheliopathies of corneal surface

CASE DESCRIPTION

Name the important tear film tests performed to

Presenting symptoms. A patient presents with a

diagnose the dry eye.

history of the bulging of the eyeball which may be

Tear film break-up-time (BUT)

gradually or rapidly progressive. It may or may not

Schirmer 1 test

be associated with visual loss, diplopia, pain or other

Rose bengal staining

symptoms.

Ocular examination reveals outward protusion of

What is tear film break-up time?

the eyeball which may be:

Tear film break-up time is the interval between a

Unilateral (Fig.16.7) or bilateral (Fig.16.11),

complete blink and appearance of the first randomly

Axial or eccentric

distributed dry spot on the corneal surface. Its normal

Pulsatile or non-pulsatile

values range between 15 and 35 seconds. Values less

Reducible or non-reducible

than 10 seconds employ an unstable tear film.

May or may not be associated with lagophthalmos

534

Comprehensive OPHTHALMOLOGY

RELATED QUESTIONS

Secondaries from:

- Neuroblastoma

What is proptosis and exophthalmos ?

- Nephroblastoma

Proptosis refers to forward displacement of the

- Ewing’s sarcoma

eyeball beyond the orbital margin. Though the word

- Leukaemic infiltration

exophthalmos (out eye) is synonymous with

proptosis; somehow it has become customary to use

5. Systemic diseases, e.g.:

the term exophthalmos for the displacement

Histiocytosis-X

associated with thyroid eye disease.

Systemic amyloidosis

Xanthomatosis

What are the causes of unilateral proptosis?

Wegener’s granulomatosis

Congenital conditions

Dermoid cyst

What are the causes of acute proptosis ?

Congenital cystic eyeball

1. Orbital emphysema following fracture of medial

Teratoma

orbital wall

Traumatic lesions

2. Orbital haemorrhage

Orbital haemorrhage

3. Rupture of ethmoidal mucocele

Retained intraorbital foreign body

Traumatic aneurysm

What are the causes of intermittent proptosis?

Inflammatory lesions

1. Orbital varix (most common cause)

Orbital cellulitis or abscess

2. Periodic orbital oedema

Panophthalmitis

3. Highlyvascular tumour

Cavernous sinus thrombosis

What are the causes of pulsatile proptosis ?

Pseudotumour

Circulatory disturbances and vascular lesions

1. Caroticocavernous fistula (most common cause)

Orbital varix

2. Saccular aneurysm of ophthalmic artery

Aneurysm

3. Congenital orbital meningocele or meningo-

Cysts of the orbit

encephalocele

Implantation cyst

4. Hiatus in the orbital roof due to trauma, operation

Hydatid cyst

or that associated with neurofibromatosis

Cysticercus cellulosae

How will you investigate a case of proptosis ?

Tumours of the orbit, which may be

Primary tumours

(arising from the various

Evaluation of a case of proptosis includes the

intraorbital structures)

following:

Secondary tumours

(invading from the

Clinical evaluation

surrounding structures)

a) History

Metastatic tumours from the distant primary

b) Local examination

tumours.

(1) Inspection;

(2) palpation;

(3)

auscultation; (4) transillumination; (5) visual

Enumerate the causes of bilateral proptosis.

acuity;

(6) pupillary reactions;

(7)

1. Developmental anomalies of the skull

fundoscopy;

(8) ocular motility;

(9)

Oxycephaly

exophthalmometry

2. Inflammatory conditions

c) Systemic examination

Mikulicz’s syndrome

II. Laboratory investigations

Late stage of cavernous sinus thrombosis

3. Endocrine exophthalmos (most common cause)

Thyroid function tests

(Fig.16.11)

Haematological tests

4. Orbital tumours, e.g.:

Stool examination for cysts and ova

Lymphoma or lymphosarcoma

Urine analysis

CLINICAL OPHTHALMIC CASES

535

III. Roentgen examination

Class 3

: Proptosis is well established.

1. Plain radiograph of orbit

Class 4

: Extraocular muscle involvement (limitation

2. CT Scanning

of movements and diplopia).

3. Ultrasonography

Class 5

: Corneal involvement (exposure keratitis)

4. Magnetic resonance imaging (MRI)

Class 6

: Sight loss due to optic nerve involvement

5. Carotid angiography

with disc pallor or papilloedema.

IV. Histopathological studies

1. Fine-needle aspiration biopsy (FNAB)

What are the two clinical types of Graves’

2. Incisional biopsy

ophthalmopathy ?

3. Excisional biopsy

1. Thyrotoxic exophthalmos (exophthalmic goitre):

In this form, a mild exophthalmos is associated

What is enophthalmos? Enumerate its causes.

with lid signs and all signs of thyrotoxicosis

Enophthalmos is the inward displacement of the

which include: tachycardia, muscle tremors and

eyeball. Its common causes are:

raised basal metabolism

1. Congenital microphthalmos

2. Thyrotropic exophthalmos

(exophthalmic

2. Congenital maxillary hypoplasia

ophthalmoplegia): In it, marked exophthalmos and

3. Traumatic blow-out fractures of the orbital floor

an infiltrative ophthalmoplegia is associated with

4. Post-inflammatory cicatrization of the extraocular

euthyroidism or hypothyroidism.

muscles as in pseudotumour syndromes

5. Paralytic enophthalmos as seen in Horner’s

What are the causes of pseudoproptosis ?

syndrome

1. Buphthalmos

6. Atrophy of the orbital contents, e.g., senile

2. Lid retraction

atrophy of orbital fat, atrophy following irradiation

3. High-axial myopia

of malignant tumours.

4. Staphyloma

5. Enophthalmos of the opposite eye

What is Graves’ ophthalmopathy ?

This is a term coined to denote typical ocular changes

What are the causes of reducible proptosis?

which include: lid retraction, lid lag and proptosis

Early stages of ocular Graves’ disease

(Fig.16.11). These changes are also known

Haemangioma

as endocrine exophthalmos, dysthyroid

Orbital varix

ophthalmopathy, thyroid ophthalmopathy and ocular

Caroticocavernous fistula

Graves’ disease (OGD).

Which is the most common primary tumour of the

Name the extraocular muscle most frequently

orbit presenting as proptosis ?

affected in Graves’ ophthalmopathy.

Cavernous haemangioma

Inferior rectus.

Name the most common primary orbital tumour

What is American Thyroid Association

of childhood.

classification of Graves’ ophthalmopathy?

Rhabdomyosarcoma

American Thyroid Association (ATA) has classified

Graves’ ophthalmopathy irrespective of the hormonal

status into the following classes; characterized by

SQUINT AND NYSTAGMUS

the acronym ‘NOSPECS’:

Class 0

: No signs and symptoms.

A CASE OF SQUINT

Class 1

: Only signs, no symptoms. Signs are

CASE DESCRIPTION

limited to lid retraction with or without

lid lag and mild proptosis.

Presenting symptoms. Patient presents with deviation

Class 2

: Soft tissue involvement with signs of

of one eye which may be on medial side (convergent

class

1 and symptoms including

squint) or lateral side (divergent squint).

lacrimation, photophobia, lid or

History of present illness must include following

conjunctival swelling.

important points:

536

Comprehensive OPHTHALMOLOGY

Age of onset

What is the nerve supply of extraocular muscles?

Mode of onset, sudden or gradual

The extraocular muscles are supplied by third, fourth

Precipitating factors such as, systemic illness

and sixth cranial nerves. The third cranial nerve

ocular cause, emotional breakdown, trauma

(oculomotor) supplies the superior, medial and inferior

History of diplopia

recti and inferior oblique muscles. The fourth cranial

Birth history is important in early childhood onset

nerve (trochlear) supplies the superior oblique muscle,

and sixth cranial nerve supplies the lateral rectus

deviation.

muscle.

History of use of glasses

Family history is also important in a case of

What are the actions of extraocular muscles?

strabismus.

Action of each extraocular muscle is as below:

Ocular examination should reveal:

Muscle

Primary

Secondary Tertiary

Whether the manifest squint is convergent (Fig.

action

13.14) or divergent (Fig.13.15).

Medial rectus

Adduction

Abnormal head posture associated or not.

Lateral rectus

Abduction

Whether the squint is unilateral or alternating

Superior rectus Elevation

Intorsion

Adduction

Ocular movements are normal

(concomitant

Inferior rectus

Depression Extorsion Adduction

squint) or limited (paralytic or non-concomitant

Superior oblique Intorsion

Depression Abduction

squint).

Inferior oblique

Extorsion Elevation Abduction

Angle of squint on corneal reflex test

(Hirschberg’s test).

Describe uniocular movements of the eyeball.

Note: Detailed orthoptic examination is not expected

Uniocular movements of the eyeball are called

from an undergraduate student.

ductions. These are as follows:

RELATED QUESTIONS

1. Adduction. It is medial rotation along the vertical axis

2. Abduction. It is lateral rotation along the vertical

Name the various extraocular muscles.

axis

Superior rectus

3. Infraduction. It is downward movement

Inferior rectus

(depression) along the horizontal axis

Medial rectus

4. Supraduction.It is upward movement (elevation)

Lateral rectus

along the horizontal axis

Superior oblique

5. Incycloduction

(Intorsion). It is rotatory

Inferior oblique

movement along the anteroposterior axis in which

superior pole of cornea (12 O’ clock point) moves

What is the origin of rectus muscles ?

medially

The rectus muscles originate from a common

6. Excycloduction

(Extorsion). It is rotatory

tendinous ring (annulus of Zinn), which is attached

movement along the anteroposterior axis in which

at the apex of the orbit.

superior pole of cornea (12 O’clock point) moves

Where are the rectus muscles inserted ?

laterally

The rectus muscles are inserted into the sclera by flat

What are version movements of the eyeball ?

tendons at different distances from the limbus as

Versions also known as conjugate movements, are

under:

synchronous (simultaneous) symmetric movements

Medial rectus

5.5 mm

of both the eyes in the same direction. For example:

Inferior rectus

6.5 mm

Dextroversion is the movement of both eyes to

Lateral rectus

6.9 mm

the right.

Superior rectus

7.7 mm

Levoversion is the movement of both eyes to the left.

CLINICAL OPHTHALMIC CASES

537

What are vergence movements of the eyeball?

What is the primary position of gaze?

Vergences, also called as disjugate movements, are

It is the position assumed by the eyes when fixing a

synchronous and symmetric movements of both eyes

distant object (straight ahead) with the erect position

in opposite directions, e.g.:

of head.

Convergence is simultaneous inward movement

What are the secondary positions of gaze?

of both the eyes.

These are the positions assumed by the eyes while

Divergence is simultaneous outward movement

looking straight up, down to the right and to the

of both the eyes.

left.

Define synergists, antagonists and yoke muscles.

What are the cardinal positions of gaze?

1. Synergists are the muscles which have a similar

These are the positions which allow examination of

primary action in the same eye, e.g., superior

each of the 12 extraocular muscles in their main field

rectus and inferior oblique of the same eye act as

of action. There are six cardinal positions of gaze, viz.

synergistic elevators.

dextroversion, levoversion, dextroelevation,

2. Antagonists are the muscles which have opposite

levoelevation, dextrodepression and levodepression.

actions in the same eye, e.g., superior and inferior

What are the three grades of binocular single

recti are the antagonists to each other in the

vision?

same eye.

Grade 1. Simultaneous macular perception (SMP):

3. Yoke muscles (contralateral synergists) are a pair

It is the power to see two dissimilar objects which

of muscles (one from each eye) which contract

can be superimposed to form a joint picture. For

simultaneously during version movements.

example, when the picture of a lion is projected onto

Different pairs of yoke muscles are as follows:

the right eye and that of a cage to the left eye, an

Right medial rectus and left lateral rectus

individual with presence of SMP will see the lion in

Right lateral rectus and left medial rectus

the cage.

Right superior rectus and left inferior oblique

Grade II. Fusion: It consists of the power to

Right inferior rectus and left superior oblique

superimpose two incomplete but similar images to

Right superior oblique and left inferior rectus

form one complete image.

Right inferior oblique and left superior rectus

Grade III. Stereopsis: It consists of the ability to

perceive the third dimension (depth perception).

What is Hering’s law of equal innervation?

According to it, an equal and simultaneous

What is squint; how do you classify it ?

innervation flows from the brain to a pair of muscles

Normally visual axes of the two eyes are parallel to

which contract simultaneously (yoke muscles) in

each other in the primary position of gaze and this

different binocular movements, e.g., during

alignment is maintained in all positions.

dextroversion, right lateral rectus muscles and left

A misalignment of the visual axes of the two eyes

medial rectus muscles receive an equal and

is called squint or strabismus. Broadly it can be

simultaneous flow of innervation.

classified as:

1. Apparent squint or pseudostrabismus

What is Sherrington’s law of reciprocal

2. Latent squint (heterophoria)

innervation?

3. Manifest squint (heterotropia), which includes:

According to it, during ocular movements an

i. Concomitant squint

increased flow of innervation to the contracting

ii. Incomitant squint.

muscles is accompanied by a simultaneous decreased

flow of innervation to the relaxing antagonists. For

What is heterophoria; what are its types ?

example, during dextroversion an increased

Also known as latent squint, it is a condition in which

innervational flow to the right lateral rectus and left

the tendency of the eyes to deviate is kept latent by

medial rectus is accompanied by a decreased flow to

fusion. Therefore, when the influence of fusion is

the right medial rectus and left lateral rectus muscles.

removed the visual axis of one eye deviates.

538

Comprehensive OPHTHALMOLOGY

Common types of heterophoria are:

What is a concomitant squint ?

1. Esophoria: It is a tendency to converge when

Concomitant squint is a type of manifest squint in

binocularity is broken by any means

which the angle of deviation remains constant in all

2. Exophoria: It is a tendency to diverge

the directions of gaze; and there is no associated

3. Hyperphoria: It is a tendency to deviate upwards,

limitation of ocular movements.

while hypophoria is a tendency to deviate

How do you classify concomitant esotropia ?

downwards. However, in practice it is customary

to use the term right or left hyperphoria, depending

1. Infantile esotropia

2. Accommodative esotropia

on the eye which remains up as compared to the

3. Non-accommodative esotropia

other.

What is accommodative esotropia?

Name a few tests by which heterophoria can be

diagnosed.

Accommodative esotropia occurs due to overaction

of convergence associated with accommodation reflex.

1. Cover-uncover test

Refractive type of accommodative esotropia is

2. Maddox rod test

associated with high hypermetropia (+4 to +7D).

3. Maddox wing test

How do you classify concomitant exotropia

What is suppression ?

(divergent squint)?

Suppression is a temporary active cortical inhibition

1. Congenital exotropia

of the image of an object formed on the retina of the

2. Primary exotropia

squinting eye. This phenomenon occurs only during

a. Intermittent

binocular vision (with both eyes open). It can be

b. Constant

tested by Worth’s four-dot test.

Unilateral

What is abnormal retinal correspondence ?

Alternating

3. Secondary (sensory deprivation) exotropia

Normally, fovea of the two eyes act as corresponding

4. Consecutive exotropia

points and have the same visual direction (normal

retinal correspondence). Sometimes in, a patient with

What is paralytic squint ?

squint, fovea of the normal eye and an extra foveal

Paralytic squint is a type of incomitant squint in which

point on the retina of the squinting eye acquire a

ocular deviation results from complete or incomplete

common visual direction, i.e., become the

paralysis of one or more extraocular muscles.

corresponding points. This adjustment is called

What are the features of paralytic squint?

abnormal retinal correspondence (ARC).

1. History of diplopia and confusion.

2. Secondary deviation is greater than primary

Name a few methods by which angle of squint can

deviation.

be measured.

3. Ocular movements are restricted towards the

1. Hirschberg’s corneal reflex test

action of paralyzed muscle.

2. Prism bar cover test (PBCT)

4. Head is turned towards the action of paralyzed

3. By synoptophore (major amblyoscope)

muscle.

4. Krimsky’s corneal reflex test

5. Perimeter method

What are the features of complete third cranial

nerve palsy ?

Describe Hirschberg’s corneal reflex test.

These include the following (Fig.13.25):

Hirschberg’s corneal reflex test is a rough but handy

1. Ptosis due to paralysis of levator muscle

method to estimate the angle of manifest squint. In it,

2. Eyeball is deviated out and slightly down

the patient is asked to fixate at a point light held at a

3. Ocular movements are restricted in all the

distance of 33 cm and the deviation of the corneal

directions except outward

light reflex from the centre of pupil is noted in the

4. Pupil is fixed and dilated

squinting eye. Roughly, the angle of squint is 15°

5. Accommodation is completely lost

and 45° when the corneal light reflex falls on the border

6. Crossed diplopia is elicited on raising the

of pupil and limbus, respectively.

eyelid

CLINICAL OPHTHALMIC CASES

539

What are the differences between paralytic and

3. Acquired nystagmus, e.g.,

non-paralytic squint ?

Acquired ocular nystagmus

Feature

Paralytic squint

Non-paralytic

Peripheral verstibular nystagmus

squint

Central vestibular nystagmus

See-saw nystagmus

Onset

Usually sudden

Usually slow

Diplopia

Usually present

Usually absent

Ocular mo-

Limited in the

Full

OCULAR INJURIES

vements

direction of action

of paralysed

A CASE OF BLUNT TRAUMA

muscle

CASE DESCRIPTION

False pro-

It is positive, i.e.,

False

Age and sex. Trauma to the eyeball may occur at any

jection

patient cannot

projection

age in either sex. However, in general, ocular trauma

correctly locate

in negative

the object in space

is more common in children than adults and males

when asked to see

than females.

in the direction of

Presenting symptoms and history. Patient usually

paralyzed muscle

presents with a direct blow to the eyeball by a large

in early stages.

blunt object (tennis ball, cricket ball, fist etc) or injuries

Head pos-

A particular head

Normal

ture

posture depending

in a road side accident. There may be associated:

upon the muscle

Visual loss

paralyzed may

Pain and swelling of varying degree

be present

Ocular examination may reveal varying signs

Nausea

Present

Absent

depending upon the extent of trauma. In general the

and vertigo

traumatic lesions produced by blunt trauma can be

Secondary

More than the

Equal to

grouped as below:

deviation

primary deviation

primary

Closed globe injury

deviation

Globe rupture

In old cases

Present

Absent

Extraocular lesions

pathological

sequelae in

For details see page 403

the muscles

RELATED QUESTIONS

What is nystagmus.

What are the common sites for retention of an

Nystagmus is defined as to-and-fro oscillatory

extraocular foreign body ?

movements of the eyes.

Sulcus subtarsalis

Fornices

What are pendular and jerk nystagmus ?

Bulbar conjunctiva

In pendular nystagmus, movements are of equal

Cornea

velocity in each direction. In jerk nystagmus, the

movements have a slow component in one direction

How do you remove a corneal foreign body?

and a fast component in the other direction. The

Eye is anaesthetized with topical instillation of 2

direction of jerk nystagmus is defined by direction of

to 4 percent Xylocaine. X3

the fast component.

Lids are separated with universal eye speculum.

What are clinical types of nystagmus ?

An attempt should be made to remove the foreign

1. Physiological nystagmus, e.g., optokinetic

body with the help of a cotton swab stick. If it

nystagmus

fails then foreign body spud or hypodermic needle

2. Congenital nystagmus, e.g.,

should be used. X3

Congenital jerk nystagmus

After removal of the foreign body, pad and

Latent nystagmus

bandage with antibiotic eye ointment is applied

Spasmus nutans

for 24 to 48 hours.

540

Comprehensive OPHTHALMOLOGY

Enumerate the lesions which can result from a

What is siderosis bulbi ?

blunt trauma to the eye (contusional injury).

Siderosis bulbi refers to the degenerative changes

Lids: Ecchymosis, Black eye, Avulsion of the

produced by an iron foreign body retained inside the

lid, Traumatic ptosis

eyeball.

Orbit: Fracture of the orbital walls, Orbital

The iron particles undergo electrolytic

haemorrhage, Orbital emphysemas

dissociation. The iron ions combine with the

Lacrimal apparatus: Laceration of canaliculi,

intracellular proteins and produce degenerative

Dislocation of lacrimal gland

changes. Epithelial structures of the eye are most

Conjunctiva: Subconjunctival haemorrhage,

affected.

Chemosis, Lacerating tears of the conjunctiva

Cornea: Abrasion, Partial or complete corneal

What are the features of siderosis bulbi ?

tear, Deep corneal opacity

1. Orangish or rusty deposits arranged radially in a

Sclera: Scleral tear

ring in the anterior capsule and anterior epithelium

Anterior chamber: Traumatic hyphaema,

of the lens

Collapse of the anterior chamber following

2. Greenish or reddish brown staining of the iris

perforation

3. Pigmentary degeneration of the retina

Iris, pupil and ciliary body:Traumatic miosis,

4. Secondary open-angle glaucoma due to

Traumatic mydriasis, Radiating tears in iris

degenerative changes in the trabecular meshwork

stroma, Iridodialysis, Traumatic aniridia,

Traumatic cyclodialysis, Traumatic uveitis

What is chalcosis ?

Lens: Vossius ring, Concussion cataract, Early

Chalcosis refers to the specific changes produced by

rosette cataract, Late rosette cataract, Total

the alloy of copper in the eye.

cataract, Subluxation of the lens, Dislocation of

Copper ions from the alloy are dissociated

the lens

electrolytically and deposited under the membran-

10.

Vitreous: Traumatic vitreous degeneration,

eous structures of the eye. Unlike iron ions, these do

Traumatic vitreous detachment, Vitreous

not enter into chemical combination with intracellular

haemorrhage

proteins and thus produce no degenerative changes.

11.

Choroid: Rupture of the choroid, Choroidal

haemorrhage, Choroidal detachment, Traumatic

What are clinical manifestations of chalcosis?

choroiditis

1. Kayser-Fleischer ring in cornea

12.

Retina: Commotio retinae (Berlin’s oedema),

2. Sunflower cataract

Retinal haemorrhages, Retinal tears, Retinal

3. Deposition of golden plaques in retina

detachment, Traumatic macular oedema,

Traumatic macular degeneration

What are the methods of localizing an intraocular

13.

Optic nerve

foreign body (IOFB):

Laceration of the optic nerve

1. Radiographic localization

Optic nerve sheath haemorrhage

1. Limbal ring method

Avulsion of the optic nerve

2. Specialized radiographic techniques, e.g., Sweet

and Dixon’s method

What are the effects of a perforating ocular injury?

2. Ultrasonographic localization

1. Mechanical effects in the form of wounds of

3. CT Scan

different parts of the eyeball

What is sympathetic ophthalmitis?

2. Introduction of infection may result in:

Purulent iridocyclitis

Sympathetic ophthalmitis is a serious bilateral

Endophthalmitis

granulomatous panuveitis which follows a penetrating

Panophthalmitis

ocular trauma. The injured eye is called the exciting

3. Post-traumatic iridocyclitis

eye and the fellow eye which also develops uveitis is

4. Sympathetic ophthalmitis

called the sympathizing eye.

CLINICAL OPHTHALMIC CASES

541

What are the predisposing factors favouring

Name the measures to prevent occurrence of

development of sympathetic ophthalmitis?

sympathetic ophthalmitis?

1. Early excision of the injured eye with no vision

1. A perforating wound

2. Meticulous repair of the wound under microscope

2. Wounds in the ciliary region

(the so-called

followed by systemic and topical steroids should

dangerous zone) are more prone to it.

be undertaken in an eye with hope of saving

3. Wounds with incarceration of the uveal tissue

useful vision.

are more vulnerable

Why alkali burns are more serious than the acid

4. It is more common in children than in adults

burns?

5. It is more common in the absence of suppuration.

Alkalies penetrate deep into the tissues unlike acids

In fact, it does not occur when actual suppuration

(which cause instant coagulation of all the proteins

develops in the injured eye

which then acts as a barrier and prevents deep

penertration) and thus produce more damage.

What are the early features of sympathetic

What are the effects of ultraviolet radiations on

ophthalmitis?

the eye ?

Photophobia

1. May produce photophthalmia

Lacrimation

2. May be responsible for senile cataract

Transient blurring of near vision

What are the effects of infra-red radiations on the

Mild ciliary tenderness

eye?

A few fine keratic precipitates

Photoretinitis (solar macular burn or eclipse burn)

CHAPTER

23^{Darkroom Procedures}

OBLIQUE ILLUMINATION, ONIOSCOPY

Subjective refraction

AND TRANSILLUMINATION

Subjective verification

Oblique illumination

Subjective refinement

Loupe and lens examination

Correction for near vision

Slit-lamp examination

OPHTHALMOSCOPY

Gonioscopy Transillumination

Distant direct ophthalmoscopy

RETINOSCOPY

Direct ophthalmoscopy

Objective refraction

Indirect ophthalmoscopy

Retinoscopy

Refractometry

Slit-lamp biomicroscopic examination

Keratometry

of the fundus

Darkroom procedures (DRPs) form an essential part

anterior segment of the eye. Karl Himly (1806) was

of examination of the eyes in modern ophthalmic

the first to employ the technique of oblique

practice. Consequently, this section has been given

illumination examination. In it, a zone of light is made

a special slot in the undergraduate as well as

to fall upon the structure to be examined so that it is

postgraduate examinations. Most of the darkroom

brilliantly illuminated and stands out with special

procedures have been described vividly with the

clarity as compared to the surroundings which remain

support of self-explanatory illustrations. Common

in shadow.

darkroom procedures are:

There are two main methods of focal illumination:

Oblique illumination examination

Loupe and lens examination; and

- Loupe and lens examination

Slit-lamp examination.

- Slit-lamp biomicroscopy

Gonioscopy

Loupe and lens examination

Transillumination

Optical principle. It is based on the principle that

Retinoscopy

when an object is placed between a convex lens and

Ophthalmoscopy

its focal point, its image formed is virtual, erect,

magnified and on the same side as the object.

Prerequisites. (1) Darkroom, (2) source of light, (3)

OBLIQUE ILLUMINATION,

condensing lens of +13 D, (4) corneal loupe of +41 D,

GONIOSCOPY AND

made with two planoconvex lenses each of 20.5 D

TRANSILLUMINATION

(×10 magnification) (Fig. 23.1).

Procedure (1) Light source is placed about 2 feet

OBLIQUE ILLUMINATION

away, laterally and slightly in front of the patient’s

Oblique illumination also known as focal illumination,

eye (2) Light is focused on the structure to be

is a method for examination of the structures of the

examined with the help of +13 D condensing lens,

544

Comprehensive OPHTHALMOLOGY

held in one hand (3) The examination is carried out

with the help of corneal loupe. The loupe is held

between thumb and forefinger of the second hand,

the fourth and fifth fingers are supported on the

patient’s forehead, while the middle finger is used for

elevating the upper lid (Fig. 23.2). The loupe is

brought close to the patient’s eye till the illuminated

area is focused. The observer should also move his

or her eyes as close to the loupe as possible to have

a better view (4) By changing the position of the

condensing lens and loupe, various structures of the

Fig. 23.3. Binocular loupe.

anterior segment can be examined one by one.

Slit-lamp examination

Slit-lamp biomicroscope was invented in 1911 by

Gullstrand. Today, biomicroscopy forms an invaluable

and indispensable part of ophthalmological

examination.

Parts. Slit lamp consists of following three parts

(Fig. 23.4):

1. Observation system (Microscope)

2. Illumination system (Slit-lamp)

Fig. 23.1. Corneal loupe.

3. Mechanical system (Engineering support)

Fig. 23.2. Technique of loupe and lens examination.

Use of binocular loupe. The corneal loupe may be

replaced by a binocular loupe (Fig. 23.3), which gives

the added advantage of stereoscopic view and easy

manoeuvring, as normally it is fixed to the examiner’s

head by a band. However, the magnification achieved

with binocular loupe is much less than that of

uniocular corneal loupe.

Fig. 23.4. The slit-lamp.

DARKROOM PROCEDURES

545

Optics

i. Examination should be carried out in semidark

It works on the same principle as a compound

room so that the examiner’s eyes are partially

microscope.

dark adapted to ensure sensitivity to low

The objective lens (+22 D) is towards the patient,

intensities of light.

whose eye forms the object. The objective lens

ii. Diffuse illumination should be used for as

consists of two planoconvex lenses with their

short a time as necessary.

convexities facing towards each other.

iii. There should be a minimum exposure of retina

The eyepiece is +10 to +14 D and is towards the

to light.

examiner.

iv. Medications like ointments and anaesthetic

The illuminating system can be adjusted to vary

eyedrops produce corneal surface disturbances

the width, height and angle of incidence of the

which can be mistaken for pathology.

light beam.

v. Low magnification should be first used to

Slit-lamp biomicroscopy routine. While performing

locate the pathology and higher magnification

slit-lamp biomicroscopy, following routine may be

should then be used to examine it.

adopted (Fig. 23.5):

Start with diffuse illumination and examine the lid

Patient adjustment. Patient should be positioned

margins, bulbar conjunctiva, limbus, cornea, tear film,

comfortably in front of the slit-lamp with his/her

aqueous, iris and the lens one by one.

chin resting on the chin rest and forehead opposed

Methods of illumination. There are 7 basic methods

to head rest.

of illumination using the slit-lamp as described by

Instrument adjustment. The height of the table

Berliner:

housing the slit-lamp should be adjusted

Diffuse illumination. A diffuse broad beam of

according to patient’s height. The microscope

light is used, and a general view of the anterior

and illumination system should be aligned with

the patient’s eye to be examined. Fixation target

segment of eye is observed.

should be placed at the required position.

Direct illumination. The slit beam and microscope

Beginning slit-lamp examination. Some points

are focused on the same area, and examination is

to be kept in mind are:

performed. Changes in the corneal stroma and

epithelium are better noted by this technique.

Indirect illumination. The slit beam is focused

on a position just beside the area to be examined.

Corneal microcysts and vacuoles can be best

observed by this method.

Retroillumination. Light is reflected off the iris

or fundus, while the microscope is focused on

the cornea. This technique is especially helpful in

detecting corneal oedema, neovascularization,

microcysts and infiltrates.

Specular reflection. Here the angle between the

slit-lamp and microscope is increased to 60°, i.e.,

angle of incidence = angle of reflection. Changes

in the endothelium like polymegathism, guttate,

etc. can be viewed by this method.

Sclerotic scatter. It utilizes the phenomenon of

total internal reflection. The slit beam is focused

at the temporal limbus, and as it passes through

the cornea, it outlines any subtle stromal or

Fig. 23.5. Technique of slit-lamp examination.

epithelial opacities which may lie in its path.

546

Comprehensive OPHTHALMOLOGY

7. Oscillatory illumination of Koeppe. In this, the

Procedure. The patient is seated upright on the slit-

beam is given an oscillatory movement by which

lamp. A drop of 1 percent methylcellulose is placed in

it is often possible to see minute objects or

the concavity of the goniolens and with the patient

filaments, especially in the aqueous which would

looking up, one edge of the lens is positioned in the

otherwise escape detection.

lower fornix. The upper lid is elevated and the patient

is instructed to look straight ahead. The lens is rotated

GONIOSCOPY

into position against the eye. When checking the

Owing to lack of transparency of corneoscleral

lateral and medial angles, the slit beam should be

junction and total internal reflection of light (emitted

horizontal and when checking the superior and inferior

from angle structures) at anterior surface of cornea it

angles, the slit beam should be vertical.

is not possible to visualize the angle of anterior

The angle structures (Fig. 23.7) seen from behind

chamber directly. Therefore, a device (goniolens) is

forwards are (Fig. 23.7) :

used to divert the beam of light and this technique of

1. Root of the iris,

biomicroscopic examination of the angle of anterior

2. Anteromedial surface of the ciliary body (ciliary

chamber is called gonioscopy.

band),

Types of goniolens.: (i) Indirect goniolens provides

3. Scleral spur,

a mirror image of the opposite angle, e.g., Goldmann

4. Trabecular meshwork and Schlemm’s canal and

(Fig. 23.6) and the Zeiss goniolens; (ii) direct

5. Schwalbe’s line

goniolens provides a direct view of the angle. Koeppe

Applications of gonioscopy

goniolens is the most popular type.

1. Classification of glaucoma into open angle and

closed angle based on configuration of the angle.

2. Localization of foreign bodies, abnormal blood

vessels or tumours in the angle.

3. Demonstration of extent of peripheral anterior

synechiae and hence planning of glaucoma

surgery.

4. Direct goniolens is used during goniotomy.

Fig. 23.6. Goldmann’s goniolens (A) and technique of

Fig. 23.7. Structures forming angle of the

gonioscopy (B)

anterior chamber.

DARKROOM PROCEDURES

547

Gonioscopic grading of angle width

What are the prerequisites for loupe and lens

examination technique?

See page 205

A darkroom

TRANSILLUMINATION

Source of light

A condensing lens of +13 Ds

Herein an intense beam of light is thrown through the

A corneal loupe of +41 Ds

conjunctiva and sclera or pupil and illumination is

observed in the pupillary area.

Where is the source of light placed in oblique

illumination examination ?

1. Trans-scleral techniques. The beam of light is

The source of light is placed slightly laterally and 2

thrown through the sclera. Normally, the pupil

feet in front of the patient’s eye.

emits a red glow but in the presence of a solid

Enumerate the structures which can be examined

mass (e.g., intraocular tumour) in the path of

with a slit-lamp without any additional aid?

light, the pupil remains black as the beam is

Lid margin

obstructed by the mass.

Conjunctiva

2. Transpupillary technique. The beam of light is

Cornea

allowed to pass obliquely through the dilated

Sclera

pupil. Normally the pupil is well illuminated but in

Anterior chamber

detached retina, a grayish reflex is seen.

Iris and pupil

Lens

RELATED QUESTIONS

Anterior part of vitreous

Who invented the technique of oblique illumination

What are the advantages and disadvantages of

examination ?

slit-lamp examination over loupe and lens

examination?

Karl Himly (1806) was the first to employ the technique

Advantages

of oblique illumination examination.

1. Magnification can be increased and decreased.

Who invented the slit-lamp ?

2. Stereoscopic vision improves depth perception.

Gullstrand

3. Aqueous flare can be better demonstrated.

What is the power of the condensing lens used in

4. Applanation tonometry and gonioscopy can be

loupe and lens examination technique?

performed with the slit-lamp.

+13Ds

Disadvantages

What is the power of a corneal loupe?

1. Slit-lamp is very costly.

2. It is not handy.

+41Ds

Enumerate a few ocular conditions where

What is the magnification of a corneal loupe?

transillumination test helps in the diagnosis.

10 x

1. Intraocular tumour

What are the advantages and disadvantages of a

2. Retinal detachment

binocular loupe over the monocular corneal

3. Vitreous haemorrhage

loupe?

Advantages

Binocular loupe provides stereoscopic vision.

RETINOSCOPY

It is easier to use.

The procedure of determining and correcting

Disadvantages

refractive errors is termed as refraction. It is an art

Magnification is less.

that can only be mastered by practice. The refraction

What is the optical principle of oblique

comprises two complementary methods, objective

illumination?

and subjective.

It is based on the principle that when an object is

OBJECTIVE REFRACTION

placed between a convex lens and its focal point, the

image formed is virtual, erect, magnified and on the

The objective methods of refraction include

same side.

retinoscopy, refractometry and keratometry.

548

Comprehensive OPHTHALMOLOGY

RETINOSCOPY

Definition

Retinoscopy also called skiascopy or shadow test is

an objective method of finding out the error of

refraction by the method of neutralization.

Principle

Retinoscopy is based on the fact that when light is

reflected from a mirror into the eye, the direction in

which the light will travel across the pupil will depend

upon the refractive state of the eye.

Prerequisites for retinoscopy

1. A darkroom, preferably 6-m long, or which can

be converted into 6 m by use of a plane mirror.

2. A trial box containing spherical and cylindrical

lenses of variable plus and minus powers, a

pinhole, an occluder and prisms.

3. A trial frame (Fig. 23.8) preferably of adjustable

type which can be used in children as well as

adults.

4. Vision box. A Snellen’s self-illuminated vision

box (Fig. 23.9).

5. Retinoscope is a simple device to perform the

retinoscopy. Broadly, retinoscopes available are

of two types:

Fig. 23.9. Snellen’s vision box.

(a) Mirror retinoscopes are cheap and the most

commonly employed. A source of light is

required when using mirror retinoscope, which

single plane mirror

(Fig.

23.10A) or

is kept above and behind the head of the

combination of plane and concave mirrors

patient. A mirror retinoscope may consist of

(Pristley-Smith mirror- Fig. 23.10B.

Fig. 23.8. Trial frame.

DARKROOM PROCEDURES

549

Fig. 23.11. Streak retinoscope.

Procedure

The patient is made to sit at a distance of 1 m from the

examiner (Fig. 23.12). With the help of a retinoscope,

light is thrown onto the patient’s eye, who is

instructed to look at a far point (to relax the

accommodation). However, when a cycloplegic has

been used, the patient can look directly into the light

and have the refraction assessed along the actual

visual axis. Through a hole in the retinoscope’s mirror,

the examiner observes a red reflex in the pupillary

area of the patient. Then the retinoscope is moved in

horizontal and vertical meridia keeping a watch on

Fig. 23.10. Mirror retinoscopes: A, plane mirror;

B, Pristley-Smith, mirror.

the red reflex (which also moves when the retinoscope

is moved).

(b) Self-illuminated retinoscopes are costly but

handy. Two types of self-illuminated

retinoscope available are: a spot retinoscope

and a streak retinoscope (Fig. 23.11). The

streak retinoscope is more popular. In it the

usual circular beam of light is modified to

produce a linear streak of light by using a

planocylindrical retinoscopy mirror. The

streak retinoscopy is more sensitive than

spot retinoscopy in detecting astigmatism.

Plane versus concave mirror retinoscope

In practice, plane mirror is used for retinoscopy. In

patients with hazy media and high degree of ametropia

concave mirror is more useful.

Fig. 23.12. Procedure of retinoscopy.

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Comprehensive OPHTHALMOLOGY

In low degrees of refractive errors the shadow (red

retinoscopy. Its effect lasts for 10 to 20 days.

reflex) seen in the pupillary area is faint and moves

2. Homatropine is used as 2 percent drops. One

rapidly with the movement of the mirror; while in high

drop is often instilled every 10 minutes for 6

degrees of ametropia it is very dark and moves slowly.

times and the retinoscopy is performed after 1 to

In the presence of astigmatism, when the axis does

2 hours. Its effect lasts for 48 to 72 hours. It is

used for most of the hypermetropic individuals

not correspond with the movement of the mirror, the

between 5 and 25 years of age.

shadow appears to swirl around.

3. Cyclopentolate is a short acting cycloplegic. Its

Use of cycloplegics in retinoscopy

effect lasts for

6 to 18 hours. It is used as 1

Cycloplegics are the drugs which cause paralysis of

percent eyedrops in patients between 8 and 20

accommodation and dilate the pupil. These are used

years of age. One drop of cyclopentolate is

for retinoscopy, when the examiner suspects that

instilled after every 10-15 minutes for 3 times

accommodation is abnormally active and will hinder

(Havener’s recommended dose) and the

the exact retinoscopy. Such a situation is encountered

retinoscopy is performed 1 to 1/½ hours or 60 to

in young children and hypermetropes. When

90 min. later, after estimating the residual

retinoscopy is performed after instilling cycloplegic

accommodation which should not exceed one

drugs it is termed as wet retinoscopy in converse to

dioptre.

dry retinoscopy (without cycloplegics). The

4. Only mydriatic

(10% phenylephrine) may be

commonly employed cyclopegics are as follows:

needed in elderly patients when the pupil is

1. Atropine is indicated in children below the age of

narrow or media is slightly hazy.

5 years. It is used as 1 percent ointment thrice

Salient features of the common cycloplegic drugs

daily for 3 consecutive days before performing are summarized in Table 23.1.

Table 23.1: Salient features of common cycloplegic and mydriatic drugs

Sl. Name of

Age of the

Dosage of

Peak

Time

Duration

Period of

Tonus

no. the drug

patient when

instillation

effect

of action

postcyclo- allowance

indicated

performing

plegic test

retinoscopy

1. Atropine

< 5 year

TDS × 3 day

2-3 days

4th day

10-20 days

After 3 weeks

sulphate

of retinoscopy

(1% ointment)

2. Homatropine

5-8 years

One drop every 60-90 min. After 90

48-72 hours

After 3 days

0.5D

hydrobromide

10 min. for

min. of

of retinoscopy

(2% drops)

6 times

instillation

of first drop

3. Cyclopentolate

8-20 years One drop every 80-90 min. After 90

6-18 hours

After 3 days

0.75D

hydrochloride

15 min. for

min. of

of retinoscopy

(1% drops)

3 times

instillation

of first drop

4. Tropicamide

Not used as One drop

20-40 min.

—

4-6 hours

—

(0.5%, 1%

cycloplegic

every 15

drops)

for retino-

min. for

scopy; used

3 to 4

only as

times

mydriatic

5. Phenyephrine Used only

One drop

30-40 min.

—

4-6 hours

—

(5%, 10%

as mydriatic every 15 min.

drops)

alone or in

for 3 to 4

combination

times

with tropica-

mide

DARKROOM PROCEDURES

551

Note: The mydriatics should be used with care in

mirror). When a simple spherical error alone is

adults with shallow anterior chamber, owing to the

present, the movements of red reflex will be

danger of an attack of narrow-angle glaucoma. In older

neutralized in both vertical as well as the horizontal

people, mydriasis should be counteracted by the use

meridia. However, in the presence of an astigmatic

of miotic drug (2% pilocarpine).

refractive error, one meridian is neutralized by adding

appropriate cylindrical lens with its axis at right angle

Observations and inferences

to the meridian to be neutralized. It is important to

Depending upon the movement of the red reflex

note that sometimes, especially, when pupil is

(Fig. 23.13) when a plane mirror retinoscope is used

dilated, two light reflexes—one central and other

at a distance of 1 metre) the results are interpreted as:

peripheral—may be seen. Under such circumstances

1. No movement of red reflex indicates myopia of

one should neutralize the central glow because the

1D.

central parts of cornea and lens are more important

2. With movement of red reflex along the movement

in forming the image on the retina.

of the retinoscope, indicates either emmetropia or

hypermetropia or myopia of less than 1 D.

The end point of retinoscopy

3. Against movement of red reflex to the movement

With simple plane mirror retinoscope the end

of the retinoscope implies myopia of more than

point of retinoscopy is neutralization of red reflex

1 D.

in all the meridia, i.e., either no movement or just

Above assertions can be easily remembered from

reversal of the movement.

the Fig. 23.14.

With a streak retinoscope at the end point streak

Neutralization

disappears and the pupil appears completely

When the red reflex moves with or against the

illuminated or completly dark (Fig. 23.13).

movement of retinoscopy we do not exactly know

Problems in retinoscopy

the amount of refractive error. However, when the

red glow in the pupil does not move then we know

Certain difficulties encountered during the procedure

for certain that patient has myopia of 1D. Therefore,

of retinoscopy are summarized below:

to estimate the degree of refractive error, the

1. Red reflex may not be visible or may be poor.

movement of red reflex is neutralized by addition of

This may happen with small pupil, hazy media and

increasingly convex (+) spherical lenses (when the

high degree of refractive error. In most cases, this

red reflex was moving with the movement of plane

difficulty is overcome by causing mydriasis and/or

mirror) or concave (-) spherical lenses (when the

use of converging light with concave mirror

red reflex was moving against the movement of plane

retinoscope.

Fig. 23.13. Red reflex during streak retinoscopy: A, neutralization point; B, with movement; C, against movement.

552

Comprehensive OPHTHALMOLOGY

Fig. 23.14. Diagrammatic depiction of the relation of movement of pupillary red reflex with the error of refraction.

2. Changing retinoscopy findings are observed due

deductions for distance (e.g., 1D for 1 m and 1.5 D

to abnormallyactive accommodation and is corrected

when retinoscopy is performed at 2/3rd m distance)

by use of cycloplegia.

and deduction for the cycloplegic when used (e.g., 1

3. Scissors shadows may sometimes be seen in

D for atropine, 0.5 D for homatropine and 0.75 D for

patients with regular astigmatism with dilated pupils.

cyclopentolate).

Mostly this difficulty is diminished with the undilated

Thus briefly

pupil.

Amount of refractive error = Retinoscopic findings -

4. Conflicting shadows moving in various directions

deduction for distance - tonus allowance for

in different parts of the pupillary area are seen in

cycloplegic drug used.

patients with irregular astigmatism.

It is customary to do retinoscopy both vertically

5. Triangular shadow may be observed in patients

and horizontally and note the values separately (Fig.

with conical cornea (keratoconus), with its apex at

23.15). In Fig 23.15 A, X denotes retinoscopy value

the apex of cone. On moving the mirror the triangular

along horizontal meridian and Y denotes the value

reflex appears to swirl around its apex (yawning

along the vertical meridian.

reflex).

When retinoscopy values along horizontal and

Static versus dynamic retinoscopy

vertical meridia are equal then there is no

Static retinoscopy refers to the procedure performed

astigmatism and a spherical lens is required to

without active use of accommodation (as described

correct the refractive error. For example: When

retinoscopic finding is 7 D with the procedure

above). Dynamic retinoscopy implies when the

preformed at

1m distance using atroprine as

procedure is performed for near vision with active

cycloplegic than appropriate refractive error will

use of accommodation by the patient. However,

be: 7D-1D (for distance) - 1D (tonus allowance

usefulness of performing dynamic retinoscopy has

for atroprine) = 5D (Fig. 23.15B)

not yet been established in refraction.

When retinoscopy values along horizontal and

Rough estimate of refractive error after

vertical meridia are unequal, then it denotes

retinoscopy

presence of astigmatism which is corrected by a

Objectively a rough estimate of error of refraction is

cylindrical lens alone or in combination with a

made by taking into account the retinoscopic findings,

spherical lens (Figs. 23.15C and D).

DARKROOM PROCEDURES

553

Fig. 23.15. A: Customary way of writing retinoscopic findings, B, C and D: Calculation for rough estimate of refractive

error: (i) Retinoscopic findings, when performed at 1m distance under atropine cycloplegia; (ii) Deduction of -1D for

distance and -1D for the atropine from the retinoscopic findings. (iii) Rough estimate of refractive error along horizontal

and vertical meridian; and (iv) Prescription required.

REFRACTOMETRY

The refractometry (optometry) is an objective method

of finding out the error of refraction by use of an

equipment called refractometer (optometer).

Refractometry utilizes the principles of indirect

ophthalmoscopy. The conventional refractometers

include dioptron, ophthalmometron, Henker’s parallax

refractometer and coincidence-refractometer.

Presently, the computerized autorefractometers (Fig.

23.16) are being used increasingly. The computerized,

autorefractometer quickly gives information about the

refractive error of the patient in terms of sphere,

cylinder with axis and interpupillary distance. This

method is a good alternative to retinoscopy in busy

practice. It is also advantageous for mass screening,

research programmes and epidemiological studies.

Fig. 23.16. Computerized autorefractometer.

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Comprehensive OPHTHALMOLOGY

The subjective verification of refraction is a must even

after autorefractometry.

KERATOMETRY

The ‘keratometry’ or ‘ophthalmometry’ is an objective

method of estimating the corneal astigmatism by

measuring the curvature of central cornea. The

keratometry readings are not of much value in routine

refraction for prescribing glasses; but are of utmost

value for prescribing contact lenses and for

calculating the power of intraocular lens to be

implanted.

Principle. Keratometer is based on the fact that the

anterior surface of the cornea acts as a convex mirror;

so the size of the image produced varies with its

curvature. Therefore, from the size of the image formed

by the anterior surface of cornea (first Purkinje image),

the radius of curvature of cornea can be calculated.

The accurate measurement of the image size is

obtained by using the principle of visible doubling.

Fig. 23.17. Basic structure of Javal and Schiotz

keratometer.

Types. Two types of keratometers used in practice

are Javal-Schiotz model and Bausch & Lomb model.

The Javal-Schiotz model keratometer consists of

two illuminated ‘mires’ (A and B) fixed on a rotatable

circular arc (C) and a viewing telescope T (Fig. 23.17).

The double images (aa¹ and bb¹) of the mires (A and

B) are formed on the cornea. Keratometry readings

are obtained by coinciding the images a¹ and b as

Fig. 23.18. Mires during keratometry with

shown in Figure 23.18. The readings are noted first in

Javal-Schiotz Keratometer.

the horizontal meridian and then the arc is rotated

by 90^o and the readings are noted in the vertical

meridian.

Bausch & Lomb keratometer (Fig. 23.19). In it, the

‘mires’ are in the form of circles (Fig. 23.20). With this

keratometer the radius of curvature of cornea in

horizontal and vertical meridia can be measured

simultaneously without rotating the mires.

SUBJECTIVE REFRACTION

Subjective refraction is meant for finding out the most

suitable lenses to be prescribed. It should always be

carried out after getting a rough estimate of the

refractive error by the objective refraction as

described above. When a cycloplegic has been used

the subjective refraction (postmydriatic test) should

be carried out preferably after 3 to 4 days (when

homatropine or cyclopentolate is used) and 3 weeks

Fig. 23.19. Bausch and Lomb Keratometer.

(when atropine is used).

DARKROOM PROCEDURES

555

before the final prescription is made. It is always better

to first refine the cylinder and then sphere.

1. Refining the cylinder. Cylinder can be refined by

either use of Jackson’s crosscylinder

(more

commonly) or by astigmatic fan test.

i. Jackson’s crosscylinder test. It is used to verify the

strength and axis of the cylinder prescribed. The

crosscylinder is a combination of two cylinders of

equal strength but with opposite sign placed with

their axes at right angles to each other and mounted

in a handle (Fig. 23.21). The commonly used

crosscylinders are of ±0.25 D and ±0.5 D.

Verification of strength of the cylinder. To check

the power of the cylinder, the crosscylinder of

± 0.25 D is placed with its axis parallel to the axis

Fig. 23.20. Mires during keratometry with Bausch &

Lomb keratometer.

of the cylinder in the trial frame first with the

same sign and then with opposite sign. In the

The technique of subjective refraction requires the

first position, the cylindrical correction is

patient’s cooperation in arriving at the proper

enhanced by 0.25 D and in the second it is

estimation of the refractive error. The proper subjective

diminished by the same amount. When the visual

refraction includes three steps:

Subjective verification of refraction.

II.

Subjective refinement of refraction, and

III. Subjective binocular balancing.

I. The subjective verification of refraction

The subjective verification of refraction can be

performed by: the ‘trial-and-error’ method. For this,

the patient is seated at a distance of 6 metres from the

Snellen’s vision chart. A trial frame is put on the face

of the patient and the visual acuity is noted for both

the eyes, separately. Then an occluder is put in front

of one eye and the appropriate lens combination (as

indicated by retinoscopy or automated refractometry)

is placed in front of the other eye. By increasing or

decreasing the power of lens the most suitable

spherical lens is chosen (the strongest convex lens

and the weakest concave lens providing best vision

should be chosen in patients with hypermetropia and

myopia, respectively). Then the axis of the cylinder

and finally its strength should by finalized using the

same ‘trial-and-error’ method. The similar procedure

is repeated for the second eye.

II. Subjective refinement of refraction

The most suitable combination of lenses chosen after

the subjective verification of refraction is refined

Fig. 23.21. Jackson’s crosscylinder.

556

Comprehensive OPHTHALMOLOGY

acuity does not improve, in either of the positions

correction of astigmatism. The 1-mm wide stenopaeic

the power of cylinder in trial frame is correct.

slit (Fig. 23.23) when placed in front of the eye allows

However, if the visual acuity improves in any of

clearest vision when it is rotated into the axis of

the positions a corresponding correction should

astigmatism and the refraction will then be indicated

be made and reverified till final correction is

by the strongest convex lens which allows full vision

attained.

in this axis and again in the axis perpendicular to it.

Verification of axis of the cylinder. Crosscylinder

2. Refining the sphere. The spherical correction is

(±0.5 D) is placed before the eye with its axis at

refined after refining the cylinder power and axis.

45^o to the axis of cylinder in trial frame (first with

Refining of the sphere is done by using following

-0.5 D cylinder and then +0.5 D cylinder or vice-

tests:

versa) and the patient is asked to tell about any

i. The fogging technique. After the cylinder power

change in the visual acuity. If the patient notices

and axis have been refined, the eye to be tested is

no difference between the two positions, the axis

fogged by insertion of about +2D spherical lens in

of the correcting cylinder in the trial frame is

myopic patients and about +4D in hypermetropic

correct. However, if the visual improvement is

patients over the previously verified sphere. The

attained in one of the positions, a ‘plus’ correcting

patient is instructed to see the distant test types

cylinder should be rotated in the direction of the

through this, and gradually the additional convex lens

plus cylindrical components of the crosscylinder

is reduced (by about 1/2 D at a time) until full vision

(and vice-versa). The test is then repeated several

is restored. This method is more useful in

times until the neutral point is reached.

hypermetropia.

ii. The astigmatic fan test. It is used to confirm the

ii. Duochrome test. It is based on the principle of

cylindrical correction. The astigmatic fan consists of

chromatic aberration. In this, the patient is asked to

a dial of lines radiating at 10° interval to one another

read the red and green letters. In an emmetropic eye

(Fig. 23.22). In this test the patient is asked to see the

the green rays are focused slightly anterior and red

fan after fogging by +0.5 D added over and above the

rays slightly posterior to the retina. Therefore, to an

best suitable combination of lenses chosen. The

emmetropic patient letters of both colours look

stigmatic patient will see all the lines equally clear. In

equally sharp. When the patient tells that he or she

the presence of astigmatism, some lines will be seen

sees red letters more clearly than the green, it indicates

more sharply defined. The concave cylinder is then

that he or she is slightly myopic. His or her spherical

added with its axis at right angles to the clearest line

lenses should be adjusted such that he or she sees

until all the lines are equally sharp.

letters of both colours with equal clarity.

iii. A stenopaeic slit-test. Though not practically

iii. Pin-hole test. It helps in confirming whether the

used now, this test also helps in checking the

optical correction in the trial frame is correct or not.

Fig. 23.22. Astigmatic fan: A, As seen by an emmetropic person; B, As seen by a patient with astigmatism at

horizontal axis.

DARKROOM PROCEDURES

557

been satisfactorily corrected, the visual acuity

at working distance of the patient should be estimated

using any of the near vision charts (Jaeger’s chart or

Snellen’s reading test types or number points types

standardized by the faculty of ophthalmologists, N5

to N48). In case near vision is defective, a suitable

convex lens addition (tested separately for each eye)

should be made over the distant correction. The near

correction added should be such that about one-third

of the amplitude of accommodation should remain as

reserve. In general, it is better to undercorrect than

to overcorrect the presbyopia (also see page 42).

RELATED QUESTIONS

Fig. 23.23. Stenopaeic slit.

LIGHT AND GEOMETRICAL OPTICS

What is the wavelength of visible spectrum of the

light?

Between 390 and 700 nm.

Which light rays are absorbed by the cornea and

crystalline lens of the eye?

Cornea absorbs rays having wavelength shorter than

295 nm and the crystalline lens of the eye absorbs

rays having wavelength shorter than 350 nm.

White light consists of how many colours?

Seven, viz. violet, indigo, blue, green, yellow, orange

and red (VIBGYOR).

What do you mean by reflection of light?

Reflection of light is a phenomenon of change in the

Fig. 23.24. Pin-hole.

path of light rays without any change in the medium.

What are the features of an image formed by a

plane mirror?

An improvement in visual acuity while looking through

It is: (i) virtual, (ii) erect and laterally inverted, (iii) of

a pin hole (Fig. 23.24) indicates that optical correction

the same size as object, and (iv) at the same distance

in the trial frame is incorrect.

behind the mirror as the object is in front.

III. Subjective binocular balancing

What do you mean by refraction of light?

The final step in the subjective refraction is binocular

Refraction of light is a phenomenon of change in the

balancing—a process sometimes known as

path of light when it goes from one medium to another.

‘equalizing the accommodative effort’ or ‘equalization

Describe the features of the images formed by a

of vision’. This allows both eyes to have the retinal

concave mirror for different positions of the

image simultaneously in focus. The details of the

object.

See Table 3.1

techniques of binocular balancing are beyond the

scope of this book.

What is total internal reflection?

When a ray of light travelling from an optically denser

Correction for near vision

medium to an optically rarer medium is incident at an

Correction for near vision is indicated usually after

angle greater than the critical angle of the pair of media

the age of 40 years. When the distance vision has

in contact, the ray is totally reflected back into the

558

Comprehensive OPHTHALMOLOGY

denser medium. This phenomenon is called total

What is fixation axis ?

internal reflection.

It is the line joining the fixation point and the centre

of rotation of the eye.

What is the critical angle ?

What is visual angle ?

Critical angle refers to the angle of incidence in the

It is the angle subtended by an object on the nodal

denser medium corresponding to which angle of

point of the reduced eye.

refraction in the rarer medium is 90°.

What are angles alpha, gamma and kappa of the

What do you mean by Sturm conoid focal interval

eye- ball ?

of Sturm and circle of least diffusion?

1. Angle alpha is the angle formed between the

Sturm conoid refers to the configuration of the light

optical axis and visual axis at the nodal point of

rays refracted through an astigmatic (toric) surface.

the eyeball.

The parallel rays of light when refracted through a

2. Angle gamma is the angle formed between the

toric surface are not focused at one point but form

optical axis and fixation axis at the centre of

two focal lines. Distance between the two lines is

rotation of the eyeball.

called focal interval of Sturm. Circle of least diffusion

3. Angle kappa is formed between the visual axis

is formed between these two lines.

and control pupillary line. A positive angle kappa

Why a patient with mixed astigmatism has

results in pseudoexotropia and a negative angle

comparatively better vision?

kappa is seen in esotropia.

Because in such patients the circle of least diffusion

What is the refractive power of the eyeball (total),

is formed on the retina.

of the cornea and the crystalline lens.

Total refractive power of the eyeball is about +60D;

OPTICS OF THE EYE

out of this +44 D is contributed by the cornea and

about +10D by the crystalline lens.

What is a ‘reduced eye’ ?

The focusing system of the eye is composed of

What are the refractive indices of the media of

the eye?

cornea, aqueous humour, crystalline lens and vitreous

Refractive indices of the media of the eye are as

humour, the optics of which, otherwise is very

follows:

complex. However, Listing has chosen a simple data

Cornea

1.37

to understand the optics of eye. This is called Listing’s

Aqueous humour

1.33

reduced eye. Its cardinal points are:

Crystalline lens

1.42

Single nodal point situated (in the posterior part

Vitreous humour

1.33

of crystalline lens) is 7.2 mm behind the anterior

surface of cornea.

REFRACTIVE ERRORS

Anterior focal point is 15.7 mm in front of the

What is emmetropia ?

anterior surface of cornea.

Emmetropia (optically normal eye) is a state of

Posterior focal point (on the retina) is 24.4 mm

refraction when the parallel rays of light coming from

behind the anterior surface of cornea.

infinity are focused at the sensitive layer of retina

Total dioptric power is about +60D.

with accommodation at rest.

What is nodal point of the eyeball?

Define ametropia.

It is the optical centre of the entire focusing system

Ametropia (a condition of refractive error) is defined

of the eye consisting of cornea, aqueous and lens

as a state of refraction when the parallel rays of light

when considered as one lens.

coming from infinity are focused either in front or

What is optical axis of the eyeball ?

behind the retina. It includes myopia, hypermetropia

It is a line passing through the centre of cornea and

and astigmatism.

centre of the lens which meets the retina on the nasal

Define hypermetropia (long-sightedness).

side of fovea.

Hypermetropia is the refractive state of the eye

What is visual axis ?

wherein parallel rays of light coming from infinity are

It is a line joining the fixation object, nodal point and

focused posterior to the retina, with accommodation

the fovea.

at rest.

DARKROOM PROCEDURES

559

What is the refractive status of the eye at birth?

Enumerate the refractive changes which occur in

At birth the eyeball is relatively short and thus most

an aphakic eye.

infants are born with +2 to +3 D hypermetropia. This

1. Eye becomes highly hypermetropic.

is gradually reduced and by the age of 5 to 7 years

2. Total power of the eye is reduced to +44Ds from

usually the eye becomes emmetropic.

+60 Ds

3. Anterior focal distance becomes 23 mm (from 15

What are aetiological types of ametropic refractive

errors?

mm in normal phakic eye)

1. Axial ametropia: There is abnormal axial length

4. Posterior focal distance becomes 31 mm (from 24

of the eyeball, too long in myopia and too short

mm in normal phakic eye).

in hypermetropia.

Name the various modalities for correction of

2. Curvatural ametropia: There is abnormal

aphakia and enumerate advantages and

curvature of the cornea or lens or both; too

disadvantages of each.

strong in myopia and too weak in hypermetropia.

1. Spectacles

3. Index ametropia: There is abnormal refractive

Advantages: It is cheap, easy and safe method of

index of the media; too high in myopia and too

correcting aphakia.

low in hypermetropia.

Disadvantages: (i) Image is magnified by 30 percent,

4. Positional ametropia: Forward displacement of

so not useful in unilateral aphakia (produce diplopia),

the lens causes myopia and backward

(ii) problems of spherical and chromatic aberrations

displacement results in hypermetropia.

may be troublesome, (iii) field of vision is limited, (iv)

prismatic effect of thick glasses causes, ‘roving ring

What are the components of the hypermetropia?

scotoma’ (v) cosmetic blemish, especially in young

Total hypermetropia = latent + manifest (facultative +

aphakics.

absolute)

2. Contact lenses

1. Total hypermetropia: It is the total amount of

Advantages: (i) Less magnification (5%) of the image,

refractive error estimated after complete

(ii) elimination of aberrations and prismatic effect of

cycloplegia with atropine.

thick glasses, (iii) wider and better field of vision, (iv)

2. Latent hypermetropia is that which is corrected

cosmetically better accepted by young persons.

by inherent tone of the ciliary muscle.

Disadvantages: (i) More cost, (ii) cumbersome to

3. Manifest hypermetropia: It is the remaining

wear, especially in old age and in childhood, (iii)

portion of total hypermetropia, which is not

corneal complications may occur.

corrected by the ciliary tone.

3. Intraocular lens implantation

Name the most common factor responsible for

It is the best available method of treatment.

myopia and hypermetropia.

Advantage: It offers all the advantages which the

Too long axial length and too short axial length are

contact lenses offer over the spectacles. In addition,

responsible for myopia and hypermetropia,

the disadvantages of contact lenses are also taken

respectively.

care of.

Name the complications which may occur in non-

Disadvantages: It requires more skilled surgeons and

treated cases of hypermetropia.

costly equipments.

1. Recurrent styes and blepharitis,

4. Refractive corneal surgery

2. Accommodative convergent squint,

It is still under trial and includes keratophakia and

3. Amblyopia.

epikeratophakia.

Define aphakia.

What are fundus findings in a patient with high

Aphakia literally means absence of the crystalline lens

hypermetropia?

from the eye. However, from the optical point of view,

Fundus examination in a patient with high

it may be considered as a condition in which the lens

hypermetropia may show:

is absent from the pupillary area and does not take

- Pseudopapillitis

part in refraction.

– shot silk appearance of the retina.

560

Comprehensive OPHTHALMOLOGY

Enumerate the signs of aphakia.

Enumerate the fundus changes in pathological

Deep anterior chamber

myopia.

Iridodonesis

1. Optic disc appears large, pale and at its temporal

Jet black pupil

edge characteristic myopic crescent is present.

Purkinje’s image test shows only two images

2. Chorioretinal degeneration.

(normally four)

3. Foster-Fuchs’ spot at the macula.

Fundus examination shows small optic disc

4. Vitreous shows synchysis and syneresis.

Retinoscopy reveals high hypermetropia

5. Posterior staphyloma may be seen.

What is pseudophakia?

Name the surgical treatment of myopia.

Pseudophakia refers to presence of an intraocular lens

1. Radial keratotomy

in the pupillary area.

2. Photorefractive keratectomy (PRK) using excimer

laser.

What is the refractive position of the pseudophakic

3. Automated microlamellar keratectomy (ALK)

eye ?

4. Removal of clear crystalline lens by extracapsular

A pseudophakic eye may be emmetropic, myopic or

hypermetropic depending upon the power of the IOL

cataract extraction (ECCE) is recommended in

unilateral very high myopia.

implanted.

What is the average standard power of the

Name the complications of pathological myopia.

posterior chamber IOL ?

Complicated cataract

Exact power of an IOL to be implanted varies from

Choroidal haemorrhage

individual to individual and is calculated by biometry

Tears and haemorrhage in the retina

using keratometer and A-scan ultrasound.

Vitreous haemorrhage

Retinal detachment

What is the average weight of an IOL?

Average weight of an IOL in air is 15 mg and in aqueous

Name the diseases which can be associated with

humour is about 5 mg.

myopia.

Microphthalmos

What is the power of the IOL in air vis-a-vis in the

Congenital glaucoma

aqueous humour?

Microcornea

Power of an IOL in air is much more (about +60D)

Retrolental fibroplasia

than that in the aqueous humour (about + 20D).

Marfan’s syndrome

What is the difference in the power of an anterior

Turner’s syndrome

chamber IOL versus posterior chamber IOL ?

Ehlers-Danlos syndrome

Equivalent power of an anterior chamber IOL is less

What is the basic principle of radial keratotomy

(say about +18D) than that of posterior chamber IOL

operation for myopia ?

(+20D).

In radial keratotomy operation, multiple radial

What is myopia (short-sightedness) ?

incisions are given in the periphery of cornea (leaving

Myopia is a refractive error in which parallel rays of

central 4 mm optical zone) in order to flatten the

light coming from infinity are focused in front of the

curvature of cornea.

retina when accommodation is at rest.

What is the principle of photorefractive

Name the clinical varieties of myopia ?

keratectomy (PRK) operation for myopia?

1. Congenital myopia

In it, superficial keratectomy (reshaping) is performed

2. Simple myopia

in the central part of cornea with the help of excimer

3. Pathological or degenerative myopia

laser.

4. Acquired myopia which may be: (i) post-traumatic,

What is ALK operation for myopia?

(ii) post-keratitis,

(iii) space myopia, and

(iv)

It is automated lamellar keratectomy. In it a small disc

consecutive myopia (following overcorrection of

of corneal stroma is removed with the help of an

aphakia by intraocular lens).

automated machine.

DARKROOM PROCEDURES

561

What is LASIK operation for myopia?

What is the most common cause of irregular

It is laser-assisted in-situ keratomileusis. It is

astigmatism?

performed using ALK machine and the excimer laser.

Irregular corneal scars.

This procedure is good for myopia of more than - 8D.

What is anisometropia?

Define astigmatism.

In it, total refraction of the two eyes is unequal.

Astigmatism is a type of refractive error, wherein the

Practically a difference of more that 2.5 D (which

refraction varies in the different meridia. Consequently,

causes more than 5% difference in the retinal images

the rays of light entering in the eye cannot converge

of the two eyes) poses problem of anisometropia.

to a point focus but form focal lines.

What is aniseikonia ?

What are the clinical types of astigmatism?

Aniseikonia is defined as a condition, wherein the

1. Regular astigmatism, which may be:

images projected to the visual cortex from the two

(i)

With-the-rule (WTR) astigmatism, wherein

retinae are abnormally unequal in size and shape.

the vertical meridian is more curved than the

How much image magnification is caused by one

horizontal.

dioptre anisometropia?

(ii) Against-the-rule (ATR) astigmatism, wherein

One dioptre anisometropia produces image

the horizontal meridian is more curved than

magnification by 2 percent. An image difference up

the vertical meridian.

to 5 percent to 7 percent is well tolerated.

(iii) Oblique astigmatism, wherein the two

What are the common causes of aniseikonia?

principal meridia are not the horizontal and

Aniseikonia may be optical

(due to high

vertical though these are at right angles to

anisometropia), retinal (due to stretching or crowding

one another (e.g., 45° and 135°).

of retina in macular area) or cortical (due to abnormal

(iv) Bioblique astigmatism, wherein the two

cortical perception of the images).

principal meridia are not at right angle to

each other, e.g., one may be at 30° and the

ACCOMMODATION AND ITS ANOMALIES

other at 100°.

2. Irregular astigmatism: In it refraction varies in

Define accommodation?

multiple meridia which admits no geometrical

Accommodation is a mechanism by which the eyes

analysis. It commonly follows corneal scarring.

can focus the diverging rays coming from a near

object on the retina. In it, there occurs increase in the

What is the treatment of irregular astigmatism?

Contact lens prescription, which replaces the anterior

power of crystalline lens.

surface of the cornea for refraction.

What is presbyopia ?

What is simple, compound and mixed

Presbyopia is not an error of refraction but a condition

astigmatism?

of physiological insufficiency of accommodation

1. Simple astigmatism. Herein the rays of light

resulting from the decreased elasticity and plasticity

entering the eye are focused on the retina in one

of the lens due to advancing age (usually after the

meridian and either in front

(simple myopic

age of 40 years) leading to failing vision for near.

astigmatism, or behind

(simple hypermetropic

What is near point of the eye?

astigmatism) the retina in other meridian.

The nearest point at which small objects can be seen

2. Compound astigmatism. In this type of

clearly is called near point or punctum proximum. Its

astigmatism, light rays are focused in both the

value varies with age; being about 7 cm at 10 years of

principal meridia either in front (compound myopic

age and about 25 cm at about 40 years of age.

astigmatism)

behind

(compound

hypermetropic astigmatism) the retina.

What is far point of the eye ?

3. Mixed astigmatism. In this condition, light rays

The farthest point from where objects can be seen by

are focused in front of the retina in one meridian

the eye is called far point or punctum remotum. In an

and behind the retina in the other meridian.

emmetropic eye, far point is at infinity.

562

Comprehensive OPHTHALMOLOGY

Enumerate the causes of premature resbyopia?

What are the prerequisites for retinoscopy?

1. Uncorrected hypermetropia

1. A darkroom preferably 6-m long or which can be

converted into 6 metres by the use of a plane

2. Premature hardening of the lens

mirror.

3. General debility causing premature senile

2. A trial box containing spherical and cylindrical

weakness of the ciliary muscle

lenses of variable plus and minus powers, a

4. Chronic simple glaucoma

pinhole, an occluder and prisms.

What is range of accommodation ?

3. A trial frame

Range of accommodation is the distance between the

4. A Snellen’s self-illuminated vision box

near point and far point of the eye.

5. A retinoscope

What is amplitude of accommodation?

What are the common types of retinoscopes?

Amplitude of accommodation is the difference

1. Mirror retinoscopes, which may consist of a

between the dioptric power needed to focus at near

simple plane mirror or a combination of a plane

point and far point.

mirror (on one end) and a concave mirror (on the

What do you mean by insufficiency of accommo-

other end). e.g., Pristley-Smith’s mirror.

dation? Enumerate its causes.

2. Self-illuminated streak retinoscope.

Insufficiency of accommodation refers to a significant

What are the advantages of a streak retinoscope

decrease in accommodation power than the normal

over a simple plane mirror retinoscope ?

physiological limit for the patient’s age. Common

The streak retinoscope is more sensitive than the spot

causes of insufficiency of accommodation are:

retinoscope in detecting astigmatism.

Premature sclerosis of the lens.

Name the conditions where concave mirror

Weakness of ciliary muscle associated with

retinoscopy is more useful.

chronic debilitating disease, anaemia, malnutrition,

1. Patient with hazy media.

pregnancy, stress and so on.

2. Patient with very high degree of refractive

Primary open-angle glaucoma.

error.

What are the indications of using cycloplegic drugs

DETERMINATION AND CORRECTION OF

for retinoscopy?

REFRACTIVE ERRORS

Cycloplegics are used before retinoscopy in patients

where the examiner suspects that accommodation is

Enumerate objective methods of refraction.

abnormally active and will hinder the exact

Retinoscopy

retinoscopy. Such a situation is encountered in young

Autorefractometry

children especially hypermetropes.

Keratometry

What do you mean by wet retinoscopy and dry

Name some subjective methods of refraction.

retinoscopy?

Trial and error method

When retinoscopy is performed after instilling a

Fogging method

cycloplegic, it is termed ‘wet-retinoscopy’ in converse

Tests for confirming refraction subjectively

to dry retinoscopy (without cycloplegic).

- Duochrome test

Name the commonly used cycloplegics.

- Astigmatic fan test

1. Atropine

- Jackson’s crosscylinder test

2. Homatropine

- Pin-hole test

3. Cyclopentolate

Define retinoscopy (skiascopy or shadow test).

At what distance retinoscopy is performed?

Retinoscopy is an objective method of finding out

One meter or two-third metre.

the error of refraction by the method of neutralization.

When retinoscopy is performed with a plane

What is the principle of retinoscopy?

mirror at a distance of 1 m; what inferences are

Retinoscopy is based on the fact that when light is

drawn?

reflected from a mirror into the eye, the direction in

Depending upon the movement of the red reflex vis-

which light will travel across the pupil will depend

a-vis movement of the plane mirror, following

upon the refractive state of the eye.

inferences are drawn:

DARKROOM PROCEDURES

563

1. No movement of the red reflex indicates myopia

letters of both the colours look equally sharp; while

of 1 D.

to a slightly myopic patient the red letters appear

2. With movement of the red reflex indicates either

sharper and to a slightly hypermetropic patient the

emmetropia or hypermetropia or myopia of less

green letters look sharper.

than 1 D.

Name common problems which can arise while

3. Against movement indicates myopia of more than

performing retinoscopy.

1D.

Red reflex may not be visible. It occurs in:

small pupil,

What inferences are drawn from the movement

hazy media, and

of the red reflex when concave mirror retinoscope

is used?

high degree of refractive errors.

The inferences drawn while using a concave mirror

DARKROOM APPLIANCES

are reverse to that of plane mirror.

What is the point of neutralization while using a

What is a prism and what are its uses in

simple plane mirror retinoscope?

ophthalmology?

The end point of neutralization is either no movement

Prism is a refracting medium, having two plane

or just reversal of the movement of the pupillary

surfaces inclined at an angle. Its uses are:

shadow.

1. Objective measurement of angle of squint (prism

bar cover test, Krimsky’s test).

What is the end point of neutralization while using

2. Measurement of fusional reserve.

a streak retinoscope?

3. Diagnosis of microtropia.

At the end point, the streak disappears and the pupil

4. Used in ophthalmic equipment such as gonios-

appears completely illuminated or completely dark.

cope, keratometer, applanation tonometer, etc.

While performing retinoscopy, if the shadow

What are the uses of a convex spherical lens?

appears to swirl around, what does it indicate?

Its uses are:

Astigmatism.

For correction of hypermetropia, aphakia

While performing retinoscopy with dilated pupil,

and presbyopia

one central and another peripheral shadow may

be seen. It is important to neutralize which

In oblique illumination examination

shadow?

In indirect ophthalmoscopy

Central shadow.

As a magnifying lens

When a cycloplegic retinoscopy has been

How will you identify a convex lens ?

performed, how many dioptres should be deducted

A convex lens can be identified from following

to compensate for the ciliary tone?

features:

1 D for atropine

It is thicker at the centre.

0.75 D for cyclopentolate

An object held close to it appears magnified.

0.5 D for homatropine

When it is moved, the objects seen through it

What is an autorefractometer?

move in the opposite direction.

It is a computerized refractometer which quickly

How will you identify a concave lens

estimates the refractive error of the patient objectively

A concave lens can be identified from following

in terms of sphere, cylinder with its axis and

features:

interpupillary distance. The subjective verification is

It is thin at the centre and thick at the periphery.

a must even after autorefractometry.

An object seen through it appears minified.

What is a duochrome test ?

When it is moved, the objects seen through it

Duochrome test is based on the principle of chromatic

move in the same direction of the lens.

aberrations. It helps in verifying the spherical

What are the uses of concave lens?

correction subjectively. In it, the patient is asked to

tell the clarity of the letters with red background vis-

For correction of myopia

a-vis green background. To an emmetropic patient,

As Hruby lens for fundus examination.

564

Comprehensive OPHTHALMOLOGY

How will you identify a cylindrical lens?

Cheap, durable and have high optical quality.

When it is rotated around its optical axis, objects

Disadvantages

seen through it become distorted.

Can cause corneal hypoxia and corneal abrasions.

It acts only in one axis, i.e., when it is moved up

What are the advantages and disadvantages of

and down or sideways the object seen through

soft contact lenses?

it moves only in one direction (with the lens in

Soft contact lenses are made up of HEMA (hydroxy-

a convex cylinder and against the lens in a

ethylmethacrylate) which is hydrophilic.

concave cylinder).

Advantages

Being soft and oxygen permeable, they are most

What are the uses of cylindrical lenses ?

comfortable and so well tolerated.

Cylindrical lens is prescribed to: (i) correct astigmatic

Disadvantages

refractive error, (ii) it is used as a crosscylinder to

Problems of proteinaceous deposits, getting cracked,

check the power and axis of the cylindrical lens

limited life, inferior optical quality, more chances of

prescribed, subjectively.

corneal infections, and inability to correct astigmatism

What is a crosscylinder and what are its uses?

of more than one dioptre.

The Jackson’s crosscylinder is a combination of two

cylindrical lenses of equal strength but with opposite

sign placed with their axis at right angles to each

OPHTHALMOSCOPY

other and mounted in a handle. The crosscylinder

effect is obtained by combining a spherical lens with

TECHNIQUES OF FUNDUS EXAMINATION

a cylindrical lens (double the power of spherical lens)

A. Ophthalmoscopy, and

with opposite sign -0.25 D spherical and +0.5 D

B. Slit-lamp biomicroscopic examination of the

cylindrical. Commonly used crosscylinders are a

fundus by:

combination of 0.25 D and 0.5 D.

Indirect slit-lamp biomiscroscopy

A crosscylinder is used to verify the strength and

Hruby lens biomicroscopy

axis of the cylinder subjectively.

Contact lens biomicroscopy

What are the uses of red and green glasses or

A. OPHTHALMOSCOPY

filters?

These are used for:

Ophthalmoscopy is a clinical examination of the

Diplopia charting

interior of the eye by means of an ophthalmoscope. It

Worth’s four-dot test

is primarily done to assess the state of fundus and

Malingering test

detect the opacities of ocular media. The

While testing, the red glass is kept in front of the

ophthalmoscope was invented by Babbage in 1848,

right eye and the green glass is kept in front of the

however its importance was not recognized, and it

left eye.

was re-invented by von Helmholtz in 1850. Three

methods of examination in vogue are: (1) distant direct

Which glass is used most commonly for making

ophthalmoscopy, (2) direct ophthalmoscopy, and (3)

spectacles?

indirect ophthalmoscopy.

Crown glass with refractive index 1.5223 is most

commonly used for making spectacles.

1. DISTANT DIRECT OPHTHALMOSCOPY

What are the types of contact lenses you know of?

Hard contact lenses

It should be performed routinely before the direct

Soft contact lenses

ophthalmoscopy, as it gives a lot of useful

information (vide infra). It can be performed with the

Rigid gas-permeable (RGP) contact lenses

help of a self-illuminated ophthalmoscope or a simple

What are the advantages and disadvantages of

plain mirror with a hole at the centre.

hard contact lenses?

Hard contact lenses are made up of PMMA

Procedure. The light is thrown into patient’s eye

(polymethylmethacrylate) which is a light weight, non-

sitting in a semi-darkroom, from a distance of 20-25

toxic but of hydrophobic material.

cm and the features of the red glow in the pupillary

Advantages

area are noted.

DARKROOM PROCEDURES

565

Applications of distant direct ophthalmoscopy

A convergent beam of light is reflected into the

i. To diagnose opacities in the refractive media.

patient’s pupil (Fig. 23.27, dotted lines). The emergent

Any opacity in the refractive media is seen as a

rays from any point on the patient’s fundus reach the

black shadow in the red glow. The exact location

observer’s retina through the viewing hole in the

of the opacity can be determined by observing

ophthalmoscope (Fig. 23.27, continuous lines). The

the parallactic displacement. For this, the patient

emergent rays from the patient’s eye are parallel and

is asked to move the eye up and down while the

brought to focus on the retina of the emmetropic

examiner is observing the pupillary glow. The

observer when accommodation is relaxed. However,

opacities in the pupillary plane remain stationary,

if the patient or/and the observer is/are ametropic, a

those in front of the pupillary plane move in the

correcting lens (equivalent to the sum of the patient’s

direction of the movement of the eye and those

and observer’s refractive error) must be interposed

behind it will move in opposite direction (Fig.

(from the system of plus and minus lenses, inbuilt in

23.25).

the modern ophthalmoscopes).

ii. To differentiate between a mole and a hole of

Characteristics of image formed. In direct

the iris. A small hole and a mole on the iris

ophthalmoscopy, the image is erect, virtual and about

appear as a black spot on oblique illumination.

15 times magnified in emmetropes (more in myopes

On distant direct ophthalmoscopy, the mole looks

and less in hypermetropes).

black (as earlier) but a red reflex is seen through

Technique. Direct ophthalmoscopy should be

the hole in the iris.

performed in a semi-darkroom with the patient seated

iii. To recognize detached retina or a tumour

and looking straight ahead, while the observer

arising from the fundus. A grayish reflex seen on

standing or seated slightly over to the side of the eye

distant direct ophthalmoscopy indicates either a

to be examined (Fig. 23.28). Patients right eye should

detached retina or a tumour arising from the

be examined by the observer with his or her right eye

fundus.

and left with the left.

2. DIRECT OPHTHALMOSCOPY

It is the most commonly practised method for routine

fundus examination.

Optics. The modern direct ophthalmoscope (Fig.

23.26) works on the basic optical principle of glass

plate ophthalmoscope introduced by von Helmholtz.

Optics of direct ophthalmoscopy is depicted in Figure

23.27.

Fig. 23.25. Parallactic displacement on distant direct

ophthalmoscopy.

Fig. 23.26. Direct ophthalmoscope.

566

Comprehensive OPHTHALMOLOGY

Fig. 23.27. Optics of direct ophthalmoscopy.

The observer should reflect beam of light from the

ophthalmoscope into patient’s pupil. Once the red

reflex is seen the observer should move as close to

the patient’s eye as possible (theoretically at the

anterior focal plane of the patient’s eye, i.e., 15.4 mm

from the cornea). Once the retina is focused the details

should be examined systematically starting from disc,

blood vessels, the four quadrants of the general

background and the macula.

3. INDIRECT OPHTHALMOSCOPY

Indirect ophthalmoscopy introduced by Nagel in

1864, is now a very popular method for examination

of the posterior segment.

Optical principle. The principle of indirect

ophthalmoscopy is to make the eye highly myopic

by placing a strong convex lens in front of patient’s

Fig. 23.28. Technique of direct ophthalmoscopy.

eye so that the emergent rays from an area of the

fundus are brought to focus as a real, inverted image

the eyeball. About 5 times magnification is obtained

between the lens and the observer’s eye, which is

with a +13 D lens. With a stronger lens, image will be

then studied (Fig. 23.29).

smaller, but brighter and field of vision will be more.

Characteristics of image. The image formed in Prerequisites. (i) Darkroom, (ii) source of light and

indirect ophthalmoscopy is real, inverted and

concave mirror or self-illuminated indirect

magnified. Magnification of image depends upon the

ophthalmoscope, (iii) convex lens (now-a-days

dioptric power of the convex lens, position of the

commonly employed lens is of +20 D), (iv) pupils of

lens in relation to the eyeball and refractive state of

the patient should be dilated.

DARKROOM PROCEDURES

567

Fig. 23.29. Optics of indirect ophthalmoscopy.

Technique. The patient is made to lie in the supine

position, with one pillow on a bed or couch and

instructed to keep both eyes open. The examiner

throws the light into patient’s eye from an arm’s

distance (with the self-illuminated ophthalmoscope).

In practice, binocular ophthalmoscope with head band

or that mounted on the spectacle frame is employed

most frequently (Fig. 23.30). Keeping his or her eyes

on the reflex, the examiner then interposes the

condensing lens (+20 D, routinely) in the path of beam

of light, close to patient’s eye, and then slowly moves

the lens away from the eye (towards himself) until the

image of the retina is clearly seen. The examiner moves

around the head of the patient to examine different

quadrants of the fundus. He or she has to stand

opposite the clock hour position to be examined, e.g.,

to examine inferior quadrant (around 6 O’clock

meridian) the examiner stands towards patient’s head

(12 O’clock meridian) and so on. By asking the patient

to look in extreme gaze, and using of scleral indenter,

the whole peripheral retina up to ora serrata can be

examined.

Fig. 23.30. Technique of indirect ophthalmoscopy.

Applications. Indirect ophthalmoscopy is essential

for the assessment and management of retinal

Formation of reflexes by the two surfaces of

detachment and other peripheral retinal lesions.

convex lens can be eliminated by slightly tilting

the lens and use of aspheric lens.

Difficulties

Advantages of the binocular indirect

1. The technique is difficult and can be mastered by

ophthalmoscope

hours of practice.

1. The inbuilt illumination is strong and its intensity

2. Reflexes from the corneal surface can be decreased

can be changed.

by holding the condensing lens at a distance

2. It allows stereoscopic view of the image.

equal to its focal length from the anterior focus

Direct versus indirect ophthalmoscopy. See

of the eye.

Table 23.2.

568

Comprehensive OPHTHALMOLOGY

Table 23.2. Direct versus indirect ophthalmoscopy

Sr.

Feature

Direct

Indirect

no.

ophthalmoscopy

Condensing lens

Not required

Required

Examination distance

As close to patient’s

At an arm’s

eye as possible

length

Image

Virtual,

Real,

Erect

Inverted

Magnification

About 15 times

4-5 times

Illumination

Not so bright; so not

Bright; so, useful

useful in hazy media

for hazy media

Area of field

About 2 disc dioptres

About 8 disc

in focus

diopter

Stereopsis

Absent

Present

Accessible fundus view

Slightly beyond equator

Up to ora serrata

Examination through hazy media

Not possible

Possible

B. SLIT-LAMP BIOMICROSCOPIC EXAMINATION

OF THE FUNDUS

Biomicroscopic examination of the fundus can be

performed after full mydriasis using a slit-lamp and

any one of the following lenses:

1. Indirect slit-lamp biomicroscopy. +78 D, +90 D

small diameter lenses (Fig. 23.31A) is presently the

most commonly employed technique for

biomicroscopic examination of the fundus.

2. Hruby lens biomicroscopy. Hruby lens is a

planoconcave lens with dioptric power 58.6D (Fig.

23.31B). This lens provides a small field with low

magnification and cannot visualize the fundus beyond

equator.

3. Contant lens biomicroscopy can be performed by

Fig. 23.31. Lenses used for slit-lamp biomicroscopic

following lenses:

examination of fundus: A, +78D or +90D, small diameter

Posterior fundus contact lens is a modified

lens. B, Hruby lens; C, Posterior fundus contact lens

Koeppe’s lens (Fig. 23.31C). The image produced

(modified Koeppe’s lens); D, Goldmann’s three-mirror

contact lens.

by it is virtual and erect.

Goldmann’s three-mirror contact lens consists

of a central contact lens and three mirrors placed

What are the types of ophthalmoscopy?

in the cone, each with different angles of

Ophthalmoscopy is of three types:

inclination (Fig. 23.31D). With this the central as

1. Distant direct ophthalmoscopy.

well as peripheral parts of the fundus can be

2. Direct ophthalmoscopy

visualized.

3. Indirect ophthalmoscopy

What are the other methods of fundus

RELATED QUESTIONS

examination?

In addition to ophthalmoscopy fundus can also be

Define ophthalmoscopy.

examined by focal illumination using a slit-lamp

It is a darkroom procedure carried out to examine the

biomicroscope and any of the following lenses:

fundus oculi.

DARKROOM PROCEDURES

569

Hruby lens

What are the characteristics of the image formed

Posterior fundus contact lens

in indirect ophthalmoscopy?

Goldmann’s three-mirror contact lens

It is real, inverted, magnified about 5 times when +13

+78 D and +90 D small diameter lenses.

D lens is used and is formed between the convex

lens and the observer.

When and who invented the direct

ophthalmoscope?

What is the power of the convex lens most

Babbage in 1848.

commonly used in indirect ophthalmoscopy?

+20 D.

Who reinvented and popularised the ophthal-

moscope?

What are the advantages of indirect ophthal-

von Helmholtz in 1850.

moscopy over direct ophthalmoscopy?

At what distance distant direct ophthalmoscopy

1. It allows a stereoscopic view of the fundus.

is performed?

2. It allows examination in hazy media.

20-25 cm.

3. Periphery of the retina up to ora serrata can be

What are the uses (applications) of distant direct

examined.

ophthalmoscopy?

What are the advantages of direct ophthal-

1. To diagnose opacities in the ocular media

moscopy over indirect ophthalmoscopy?

2. To differentiate between a mole and a hole of the

1. It is a handy procedure

iris.

2. Easy to perform

3. To recognize a detached retina

3. Allows examination of the minute details of the

4. To recognize a subluxated lens.

approachable lesion, since image formed is 15

At what distance ‘direct ophthalmoscopy’ should

times magnified.

be performed?

4. Orientation and understanding of the lesion is

As near to the patient’s eye as possible.

easy as the image formed is erect.

What are the features of the image formed in direct

Name the common diseases of the optic disc

ophthalmoscopy?

which can be diagnosed on direct

The image formed is erect, virtual and about 15 times

ophthalmoscopy.

magnified in an emmetrope.

Papillitis

When and who invented the indirect ophthalmo-

Papilloedema

scopy?

Optic atrophy

Nagel in 1864

Glaucomatous cupping

What is the principle of indirect phthalmoscopy?

The principle of indirect ophthalmoscopy is to make

Name few common retinal disorders diagnosed

on direct/ indirect ophthalmoscopy.

the eye highly myopic by placing a strong convex

Diabetic retinopathy

lens in front of the patient’s eye so that emergent

rays from an area of the fundus are brought to focus

Hypertensive retinopathy

as a real, inverted image between the lens and the

Retinal detachment

observer’s eye.

Retinitis pigmentosa

CHAPTER

24^Oper

tive Ophthalmology

INTRODUCTION

Ophthalmic instruments

ANAESTHESIA FOR OCULAR SURGERY

Regional (local) anaesthesia

STERILIZATION, DISINFECTION

General anaesthesia

AND FUMIGATION

OPHTHALMIC EQUIPMENT AND

Sterilization and disinfection

INSTRUMENTS

Fumigation

Essential equipment for ophthalmic

operation theatre

RELATED QUESTIONS

low intraocular pressure with dilated pupil. Above

INTRODUCTION

all, in developing countries like India, with a large

number of cataract cases, it is much more economical.

To perform well in this section of practical

examinations, students are supposed to be well versed

REGIONAL (LOCAL) ANAESTHESIA

with the following topics:

Indications. Almost all ocular operations, namely,

Anaesthesia for ocular surgery

cataract extraction, glaucoma surgery, keratoplasty

Ophthalmic equipment

and other corneal surgeries, iridectomy, squint and

Ophthalmic instruments

retinal detachment surgery in adult can be performed

Sterilization techniques

under local anaesthesia.

Surgical steps of common eye operations

Goals. The main goals of regional anaesthesia for

- Cataract surgery (see page 187)

successful ocular surgery are: globe and conjunctival

- Glaucoma surgery (see page 237)

anaesthesia, orbicularis akinesia, ocular akinesia and

- Enucleation operation (see page 284)

low intraocular and intraorbital pressure.

- Evisceration operation (see page 154)

These goals can be achieved by a local anaesthesia

Lasers and cryotherapy in ophthalmology (see

comprising either surface anaesthesia, facial block

page 430-432)

and retrobulbar block or a combination of surface

anaesthesia and peribulbar block.

Surface (Topical) anaesthesia

ANAESTHESIA FOR OCULAR

Surface anaesthesia achieved by topical instillations

SURGERY

of 2 to 4 percent xylocaine or 1 percent amethocaine.

Ocular surgery may be performed under topical, local

Usually a drop of anaesthetic solution instilled 4 times

or general anaesthesia. Local anaesthesia is more

after every 4 minutes is sufficient to produce

frequently employed as it entails little risk and is less

conjunctival and corneal anaesthesia. Cataract

dependent upon patient’s general health. It is easy to

surgery by phacoemulsification can be performed

perform, has got rapid onset of action and provides a

under topical anaesthesia.

572

Comprehensive OPHTHALMOLOGY

Facial block

For intraocular surgery it is necessary to block the

facial nerve which supplies the orbicularis oculi

muscle, so that patient cannot squeeze the eyelids.

Orbicularis akinesia can be achieved by blocking

the facial nerve at its terminal branches (van Lint

block), superior branches (Atkinson block) or

proximal trunk (O’Brien or Nadbath block).

1. Blocking the peripheral branches of facial nerve

(van Lint’s block): This technique blocks the terminal

branches of the facial nerve, producing localized

akinesia of the orbicularis oculi muscle without

associated facial paralysis.

In this technique, 2.5 ml of anaesthetic solution is

injected in deeper tissues just above the eyebrow

Fig. 24.2. Diagrammatic distribution of the facial nerve

and just below the inferior orbital margin, through a

and technique of O'Brien’s block.

point about 2 cm behind the lateral orbital margin,

4. Atkinson’s block: In it superior branches of the

level with outer canthus (Fig. 24.1).

facial nerve are blocked by injecting anaesthetic

solution at the inferior margin of the zygomatic bone.

Retrobulbar block

Retrobulbar block was introduced by Herman Knapp

in 1884. It is administered by injecting 2 ml of anaesthetic

solution (2% xylocaine with added hyaluronidase 5 IU/

ml and with or without adrenaline one in one lac) into

the muscle cone behind the eyeball (Fig. 24.3 position

‘B’). It is usual to give the injection through the inferior

fornix or the skin of outer part of lower lid with the eye

in primary gaze (Fig. 24.4 position ‘B’). The needle is

first directed straight backwards then slightly upwards

and inwards towards the apex of the orbit, up to a depth

Fig. 24.1. Technique of van Lint’s block.

of 2.5 to 3 cm.

2. Facial nerve trunk block: at the neck of mandible

(O’Brien’s block). In it, facial nerve is blocked near

the condyloid process. The condyle is located 1 cm

anterior to the tragus. It is easily palpated if the

patient is asked to open and close the mouth with the

operator’s index finger located across the neck of the

mandible. At this point the needle is inserted until

contact is made with the periosteum and then 4 to 6

ml of local anaesthetic is injected while the needle is

withdrawn (Fig. 24.2).

This technique is associated with pain at the

injection site and unwanted facial paralysis.

3. Nadbath block: In this technique, the facial nerve

Fig. 24.3. Position of needle for peribulbar block in the

is blocked as it leaves the skull through the

peripheral orbital space (A) and for retrobulbar block in

stylomastoid foramen. This block is also painful.

the muscle cone (B).

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

573

Retrobulbar block anaesthetizes the ciliary nerves,

GENERAL ANAESTHESIA FOR OCULAR

ciliary ganglion and third and sixth cranial nerves thus

SURGERY

producing globe akinesia, anaesthesia and analgesia.

Indications include infants and children, anxious,

The superior oblique muscle is not usually paralyzed

unco-operative and mentally retarded adults,

as the fourth cranial nerve is outside the muscle cone.

perforating ocular injuries, major operations like

Complications encountered with it include

exenteration and the patients willing for operation

retrobulbar haemorrhage, globe perforation, optic

under general anaesthesia.

nerve injury, and extraocular muscle palsies.

Important points. During general anaesthesia for

ocular surgery, use of relaxants, endotracheal

Peribulbar block

intubation and controlled respiration is preferred.

This technique described in 1986 by Davis and Mandel

Under general anaesthesia, it must be ensured that

has almost replaced the time-tested combination of

patient does not develop carbon dioxide retention.

retrobulbar and facial blocks, because of its fewer

When this occurs, choroid swells to many times its

complications and by obviating the need for a separate

normal value and ocular contents prolapse as soon

facial block.

as the eye is opened.

Primarily the technique involves the injection of 6

In perforating injuries and other ocular emergency

to 7 ml of local anaesthetic solution in the peripheral

cases, use of suxamethonium should always be

space of the orbit (Fig. 24.3 position ‘A’), from where

preferred over non-depolarizing relaxants as the risk

it diffuses into the muscle cone and lids; leading to

of vomiting and regurgitation of stomach contents is

globe and orbicularis akinesia and anaesthesia.

less with it.

Classically, the peribulbar block is administered by

two injections; first through the upper lid (at the

junction of medial one-third and lateral two-third) and

OPHTHALMIC EQUIPMENT AND

second through the lower lid (at the junction of lateral

one-third and medial two third (Fig. 24.4 position ‘A’).

INSTRUMENTS

After injection orbital compression for 10 to 15

minutes is applied with superpinky or any other

ESSENTIAL EQUIPMENT FOR OPHTHALMIC

method.

OPERATION THEATRE

The anaesthetic solution used for peribulbar

In addition to the basic requirements of general

anaesthesia consists of a mixture of 2 per cent

operation theatre with equipment for general

lignocaine, and 0.5 to 0.75 per cent bupivacaine (in a

anaesthesia and facilities to deal with the cardio-

ratio of 2:1) with hyaluronidase 5 IU/ml and adrenaline

respiratory emergency situations, a modern

one in one lac.

ophthalmic operation theatre should also have the

following equipment:

An operating microscope (Fig. 24.5A),

An ophthalmic cryo unit (Fig. 24.5B),

A wet-field bipolar cautery (Fig. 24.5C),

An electrolysis machine,

An electromagnetic unit for removal of intraocular

foreign bodies,

A vitrectomy unit (Fig. 24.5D), and

Phacoemulsification machine

(Fig.

24.5E) for

modern cataract surgery.

OPHTHALMIC INSTRUMENTS

Fig. 24.4. Position of the needle on the skin for peribulbar

Commonly used ophthalmic instruments can be

block (A) and retrobulbar block (B).

grouped as under:

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

575

2. Eye speculum with guard (Fig. 24.7). It also keeps

(iv) To hold skin during eyelid surgery. (v) To hold

the lashes away from the field of operation.

nasal mucosal flaps and lacrimal sac flaps in DCR

operation.

Fig. 24.9.

2. Globe fixation forceps (Fig. 24.10). It has 2 × 3 or

Fig. 24.7.

3 × 4 teeth at the tip. It is applied near the limbus to

hold the conjunctiva and episcleral tissue together.

3. Wire speculum (Fig. 24.8). It is very light and

Uses: (i) To fix the eyeball during operations on the

causes minimal pressure on the eyeball. It is also

eyeball. (ii) To hold the eyeball during forced duction

universal.

test.

Fig. 24.10.

3. Superior rectus holding forceps (Fig. 24.11). It is

a toothed forceps (1 × 2 teeth) with S-shaped double

curve near the tip. Uses: It is used to hold the superior

rectus muscle while passing a bridle suture under it;

to stabilize the eyeball during any operation such as

cataract surgery, glaucoma surgery, corneal surgery,

etc.

Fig. 24.8.

Uses. Eye speculums are used to keep the lids apart

during:

Any intraocular operation such as cataract surgery

and glaucoma surgery.

Fig. 24.11.

Any extraocular surgery e.g., squint surgery,

4. Corneo-scleral forceps. These are available in

pterygium surgery.

many shapes and designs. Commonly used are

Enucleation and evisceration operation.

Colibri forceps (Fig. 24.12 A) and Lim’s forceps

Removal of conjunctival and corneal foreign

(Fig. 24.12 B). These are the forceps with very fine

bodies.

teeth (1 × 2) at the tip. Uses: These are used to hold

Cauterization of corneal ulcer.

the cornea or scleral edge (of incision) for suturing

Examination of the eye in a patient with

during cataract, glaucoma, repair of corneal and/or

blepharospasm.

scleral tears and keratoplasty operations.

II. Forceps

Many kinds of forceps are available for different

purposes. A few common ones are mentioned here.

1. Plain forceps (Fig. 24.9). It is simple forceps

Fig. 24.12 A

without any teeth. Serrations (either horizontal or

vertical) are present near the tip. Uses: (i) To hold the

conjunctiva during any surgical procedure. (ii) To tie

sutures. (iii) To hold scleral flap in trabeculectomy.

Fig. 24.12 B

576

Comprehensive OPHTHALMOLOGY

5. Iris forceps (Fig. 24.13). These are small and

bleeding vessels during operations of the lids and

delicate forceps having fine 1 × 2 teeth on the inner

lacrimal sac. (ii) To hold the skin and muscle stay

side of the limbs. These are also available in various

sutures. (iii) To hold small ‘pea-nut’ gauze pellets for

shapes and designs. Uses: These are used to catch

blunt dissection in lacrimal sac surgery and other

the iris for the purpose of iridectomy during

extraocular surgery. (iv) To hold gauze pieces while

operations for cataract, glaucoma, optical iridectomy

packing the socket after enucleation or exentration

and excision for iris prolapse, tumours and entangled

operation.

foreign bodies.

Fig. 24.13

6. Arruga’s intracapsular (capsule holding) forceps

Fig. 24.16

(Fig. 24.14). Intracapsular forceps have a cup on the

III. Hooks and retractors

inner side of the tip of each limb. The margins of the

cup are very smooth which do not damage the lens

1. Lens expressor (hook) (Fig. 24.17). It is a flat metal

capsule when applied. Uses: It is used to hold the

handle with a rounded curve at one end. Tip of the

lens capsule (usually at 6 O’clock position) during

curve is knobbed. The plane of the handle is at right

capsule forceps method of lens delivery in

angle to the curvature of the hook. Uses: (i) To apply

intracapsular cataract extraction. It is also used to

pressure on the limbus at the 6 O'clock position during

grasp and remove the capsular remnants after

the delivery of lens in intracapsular cataract extraction

accidental extracapsular lens extraction.

with Smith’s (tumbling) and capsule forceps

techniques.

(ii) To express the nucleus in

extracapsular cataract extraction. (iii) It can also be

used as muscle hook if the latter is not available. (v)

Also used along with wire vectis to extract out the

Fig. 24.14

dislocated lens.

7. Epilation forceps (Fig. 24.15). These are small

stout forceps with blunt and flat ends. Uses: These

are used to epilate the cilia in trichiasis and stye, to

Fig. 24.17

remove cilia after electrolysis and cryolysis and to

2. Muscle (strabismus) hook (Fig. 24.18). It is similar

remove cilia lodged in the punctum.

to the lens expressor in appearance but has a blunt

gaurding knob at the end to prevent muscle slippage.

The plane of the handle is the same as that of the

curvature of the hook. Uses: (i) It is used to engage

Fig. 24.15

the extraocular muscles during surgery for squint,

enucleation, and retinal detachment. (ii) In the

8. Artery (haemostatic) forceps (Fig. 24.16). It is a

absence of lens expressor, it may be used in its place.

blunt-tipped stout forceps having a scissors-like

configuration. It has multiple straight grooves (at right

angle to the limbs) near the tip and a locking mechnism

near the ringed end. These are available in large,

Fig. 24.18

medium and small size. The small-sized artery forceps,

also called as mosquito artery forceps are more

3. Desmarre’s retractor (Fig. 24.19). It is a saddle-

commonly used in ophthalmology. These can be

shaped instrument folded on itself at one end. It is

straight or with curved ends. Uses: (i) To catch the

available in two sizes: small (paediatric) and large

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

577

(adult). Uses: It is used to retract the lids during

examination of the eyeball in cases of blepharospasm

in children, in cases with marked swelling and

Fig. 24.22

ecchymosis, removal of corneoscleral sutures,

IV. Needle holders

removal of corneal foreign body and for double

eversion of upper lid to examine the superior fornix.

1. Spring action (Barraquer’s type) needle holder

Advantages. Allows continuous adjustment of the

(Fig. 24.23). These are available in various sizes with

lids and width of the palpebral aperture.

straight or curved tips, in different shapes and may

be with or without locking system. The jaws of the

needle holder are finely serrated to hold the fine

needles firmly. Uses: Spring type needle holders are

Fig. 24.19

used for passing sutures in the conjunctiva, cornea,

sclera and extraocular muscles.

Disadvantages. It is not self-retaining, so an assistant

is needed to hold it.

4. Cat’s paw lacrimal wound retractor (Fig. 24.20).

It is a fork-like instrument with the terminals bent

inward. Uses: It is used to retract the skin during

lacrimal sac and lid surgery.

Fig. 24.23

2. Castroviejo’s needle holder (Fig. 24.24). It is a

medium-sized spring action needle holder with a

Fig. 24.20

S-shaped locking system. Uses. It is generally used

5. Self-retaining lacrimal wound (Muller ’s)

in extraocular surgery e.g., conjunctival suturing,

retractor (Fig. 24.21). It is made up of two limbs with

squint surgery etc. It can also be used for intraocular

three curved pins on each for engaging the edges of

surgery.

the skin incision. The limbs are kept in a retracted

position with the help of a fixing screw. Uses: It is

used to retract the skin during surgery on the lacrimal

sac (e.g., DCT or DCR).

Fig. 24.24

3. Arruga’s, Stevens’, Silcock’s and Kelt needle

holder (Fig. 24.25). These are large needle holders

and all are of similar type with slight model differences.

The upper shank of these needle holders has a flat

and broad plate to accommodate the surgeon’s thumb.

Fig. 24.21

These are available with and without locking device.

Uses: These are very commonly used in lid surgery

6. Iris retractor (Fig. 24.22). It consists of a handle

and also for passing superior rectus suture.

with a curved blade (which conforms to the pupillary

margin) at one end. Its edges and corners are rounded

so as not to damage either the iris or the lens capsule.

Uses: To retract the upper edge of pupil in

cryoextraction technique of ICCE and also to aspirate

the lens matter from behind the iris at 12 O’clock

position in ECCE.

Fig. 24.25

578

Comprehensive OPHTHALMOLOGY

V. Callipers and rules

1. Castroviejo calliper (Fig. 24.26). It is a divider-

like instrument, to one arm of which is attached a

graduated scale (in mm). Its other arm can be moved

by a screw over the scale. Uses: It is used to take

measurements during squint, ptosis, retinal

Fig. 24.28

detachment and pars plana vitrectomy surgery. It is

3. Paracentesis needle (Fig. 24.29). It is a small lancet-

also used to measure corneal diameter and visible

shaped needle with sharp cutting edges resembling

horizontal iris diameter.

in appearance a small keratome. It has got a guard to

prevent inadvertent injury to the deeper structures.

Uses: It is used for paracentesis and to make very

small corneoscleral incisions.

Fig. 24.26

Fig. 24.29

2. Metallic rule: It is used as a scale for the

Castroviejo calliper for exact measurements and to

4. Tooke’s knife (Fig. 24.30). It has a short flat blade

measure the palpebral aperture width.

with a semicircular blunt dissecting edge, which is

bevelled on both the surfaces like a chisel. Uses: (i) It

V. Knives and knife-needlesh

can be used to separate the conjunctiva and

1. Von Graefe’s knife (Fig. 24.27). It is a long, narrow,

subconjunctival tissue from the sclera and limbus

thin and straight blade with a sharp tip and cutting

when limbal based flap is made for trabeculectomy

edge on one side. It is not used presently Uses: (i)

surgery. (ii) It can also be used to separate partial

Previously it was used for making an abinterno

thickness lamellae of sclera during trabeculectomy.

corneoscleral incision during cataract surgery and

(iii) To separate pterygium head or limbal dermoid

for iridectomy operation. (ii) It is also used for four-

from the underlying corneal lamellae. (iv) To separate

dot iridectomy operation in patients with iris bombe

corneal lamellae in lamellar keratoplasty.

formation. (iii) For making a puncture in pars plana

area during lensectomy and vitrectomy operation.

Fig. 24.30

Fig. 24.27

5. 15° side port entry blade (Fig. 24.31). It is a fine

2. Keratomes (Fig. 24.28). A keratome has a thin

straight knife with a sharp pointed tip and cutting

diamond-shaped blade with a sharp apex and two

edge on one side. Uses. It is used to make a small

cutting edges. Straight as well as curved keratomes

valvular clear corneal incision (commonly called as

are available in various sizes (2.8 mm, 3mm, 3.5mm,

side port incision) in phacoemulsification and other

5.5 mm). Presently disposable curved keratomes are

intraocular surgeries including pars plana vitrectomy.

more commonly used. Uses. Keratomes are used to

make valvular corneal incisions for entry into the

anterior chamber for all modern techniques of cataract

extraction viz. phacoemulsification, SICS and even

conventional ECCE and other intraocular surgeries,

iridectomies and paracentesis. Recently keratomes are

being used for making self-sealing incisions for

phacoemulsification and manual SICS operation.

Fig. 24.31

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

579

6. MVR or V lance blade (Fig. 24.32). It is a fine

straight but triangular knife similar to 15° side port

entry blade but with cutting edges on both sides.

Uses. Its uses are similar to 15° side port entry blade.

Fig. 24.36

10. Crescent knife (Fig. 24.37) . It is blunt-tipped,

Fig. 24.32

bevel up knife having cut-splitting action at the tip

7. Cystitome or capsulotome (Fig. 24.33). It is a small

and both the sides. Its blade is curved and either

needle knife with a bent tip which is sharp on both

mounted on a plastic handle (disposable) or can be

fixed with metallic handle. Uses: It is used to make

the edges. Presently disposable cystitome is prepared

tunnel incision in the sclera and cornea for

by bending the disposable 26 gauge or 30 gauge

phacoemulsification, manual small incision cataract

hypodermic needle. Uses: It is used for doing anterior

surgery (SICS), and sutureless trabeculectomy.

capsulotomy or capsulorhexis during extracapsular

cataract extraction.

Fig. 24.37

Fig. 24.33

VI. Scissors

1. Plain straight scissors (ringed) (Fig. 24.38): It is a

8. Foreign body spud (Fig. 24.34). It has a small, stout

fine pointed scissors with straight sharp cutting

and flat blade with blunt tip and edges on both sides.

blades. Uses: It is used to cut conjunctival sutures,

Uses: It is used to remove corneal foreign body.

eyelashes, and muscles.

Fig. 24.34

9. Razor blade fragment with blade holder. Razor

blade fragment holder (Fig. 24.35) is designed to hold

the razor blade fragment firmly in its jaws and has a

locking device. The razor blade fragments broken to

a uniform size and shape have the sharpest possible

Fig. 24.38

metal edge with an absolute point. Presently pre-

sterilized razor blade fragments mounted on a

2. Plain curved scissors (ringed) (Fig. 24.39). It is a

disposable plastic handle (Fig. 24.36) are also being

fine pointed scissors with curved, sharp cutting

preferred. Uses: It is the most commonly used cutting

blades. Uses: It is used to cut and undermine

device for making incisions in cataract, glaucoma,

conjunctiva in various operations and to undermine

keratoplasty, sclerotomy, pterygium and many other

skin during operations on lids and lacrimal sac.

operations.

Fig. 24.35

Fig. 24.39

580

Comprehensive OPHTHALMOLOGY

3. Tenotomy scissors or strabismus scissors (Fig.

24.40). They are plain straight or curved scissors with

blunt ends. Uses: (i) To cut the extraocular muscles

during squint surgery and enucleation operation. (ii)

Fig. 24.42

To separate the delicate tissues without damaging

the surrounding area in oculoplastic operations and

6. Spring scissors (Westcott’s) (Fig. 24.43). They are

squint surgery.

stout scissors available with straight or curved blades

with sharp or blunt tips. The blades are kept apart by

spring action. Uses: They are used as a handy

alternative to plain straight and plain curved ringed

scissors for cutting and undermining conjunctiva in

various operations and to cut sutures.

Fig. 24.40

4. Corneal scissors or section enlarging scissors

Fig. 24.43

(Fig. 24.41 A & B). They are fine curved scissors.

7. Vannas scissors (Fig. 24.44). These are very fine

Their cutting blades are kept apart by spring action.

delicate scissors with small cutting blades kept apart

They are available in various shapes and sizes. The

by spring action. The blades may be straight or

universal corneal scissors can be used for both sides

curved. Uses: (i) These are used for cutting anterior

while right and left curved corneal scissors are

capsule of the lens in extracapsular surgery and for

separated for the two sides. Uses: (i) These are used

cutting 10-0 nylon sutures. (ii) For cutting inner scleral

to enlarge corneal or corneoscleral incision for

flap in trabeculectomy. (iii) For doing pupillary

conventional intracapsular and extracapsular cataract

sphincterotomy. (iv) For performing iridectomy. (v)

extraction (sparingly performed procedures now-a-

For cutting pupillary membrane.

day) cataract surgery. (ii) To enlarge corneal incision

in keratoplasty operation. (iii) To cut the scleral and

trabecular tissue in trabeculectomy.

Fig. 24.44

8. Enucleation scissors (Fig. 24.45). They are large,

Fig. 24.41A

stout and strong scissors having curved sharp blades

with blunt ends. Uses: They are used to cut the optic

nerve during enucleation operation.

Fig. 24.41B

5. de Wecker’s scissors (Fig. 24.42). They are fine

scissors with small blades directed at right angles to

Fig. 24.45

the arms. The blades are kept apart, making V-shape,

by spring action. Uses: It is used to perform iridectomy,

VII. Clamps

iridotomy and to cut the prolapsed formed vitreous

1. Lid clamp or entropion clamp (Fig. 24.46). It

and pupillary membrane.

consists of a D-shaped plate opposed by a U-shaped

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

581

rim, which when tightened with the help of a screw,

VIII. Additional instruments for cataract surgery

clamps the tissues. Two clamps are required; one can

1. Lens spatula (Fig. 24.49). It is a flat metallic handle

be used for right upper and left lower lid and the

with tiny spoon-shaped ends. It is used to apply

second for right lower and left upper lid. While

counter-pressure at 12 O’clock position during

applying the lid clamp, the plate is kept towards the

extraction of lens in Smith’s technique and expression

conjunctival side, the rim on the skin side, and the

of nucleus in extracapsular cataract extraction.

handle is always situated on the temporal side.

Advantage over lid spatula: It is a self-retaining

instrument and does not need an assistant to hold.

Disadvantages: (i) Operative field is less. (ii) Pressure

Fig. 24.49

necrosis can occur if fitted tightly. Uses: It is used in

2. Wire vectis (Fig. 24.50). It is wire loop attached to

lid surgery e.g., entropion, and ectropion corrections.

It protects the eyeball, supports the lid tissue and

a metallic handle. Uses: It is used to remove dislocated

provides haemostasis during surgery.

or subluxated lens. and nucleus in ECCE.

Fig. 24.50

3. Irrigating wire vectis (Fig. 24.51). Is is a modified

vectis in which the loop is made of a thick hollow

Fig. 24.46

wire. The anterior end of the loop has three 0.3-mm

2. Chalazion clamp (Fig. 24.47). It consists of two

openings. The posterior end of the loop is continuous

limbs like forceps, which can be clamped with the

with a hollow handle. The posterior end of the hollow

help of a screw. The tip of one limb is flattened in the

handle has a hub similar to that of a hypodermic needle

form of round disc while the tip of the other arm has a

to which is attached a syringe or infusion set. The

small circular ring. Usually the flat disc is applied on

size of the loop of the vectis is variable. In commonly

the skin side and ring on the conjunctival side of the

used wire vectis the loop is 4 mm in width and about

chalazion. Uses: To fix the chalazion and achieve

8-9 mm in length. The superior surface of the loop

haemostasis during incision and curettage.

has a slight concavity to accommodate the lens

nucleus. Uses. Irrigating wire vectis is most commonly

used to deliver nucleus in manual small incision

cataract surgery (SICS) and in conventional ECCE by

hydroexpression or viscoexpression technique.

Fig. 24.47

3. Ptosis clamp (Fig. 24.48). It is like forceps with J-

shaped ends having internal serrations. The clamp

has a locking mechanism. Use: To hold levator

palpebrae superioris muscle during ptosis surgery.

Fig. 24.51

4. Two-way irrigation and aspiration cannula (Fig.

24.52). It is available in various designs, commonly

used are Simcoe’s classical or reverse cannula. Uses:

(i) For irrigation and suction of the lens matter in

extracapsular cataract extraction. (ii) Aspiration of

Fig. 24.48

hyphaema.

582

Comprehensive OPHTHALMOLOGY

3. Sinskey hook or IOL dialer (Fig. 24.56). It is a fine

but stout instrument with a bent tip. The tip engages

the dialing holes of the IOL. Uses: (i) It is used to dial

the PMMA non-foldable IOL for proper positioning

in the capsular bag or ciliary sulcus. (ii) It can also be

used to manipulate the nucleus in phacoemulsification

surgery. Nucleus mani-pulation may be in the form of

nucleus rotation in the capsular bag, cracking of the

nucleus and feeding of the nuclear fragments into

the phaco tip.

Fig. 24.52

5. Iris repositor (Fig. 24.53). It consists of a delicate,

flat, malleable, straight or bent blade with blunt edges

and tip attached to a handle. Uses: (i) To reposit the

Fig. 24.56

iris in the anterior chamber in any intraocular surgery.

4. Hydrodissection cannula (Fig. 24.57). It is a single

(ii) To break synechiae at the pupillary margin.

bore 25G, 27G or 30 G cannula wih a 45° angulation at

about 10 to 12 mm from the free end. The tip at the

free end can be flattened or bevelled. Uses. It is used

to perform hydrodissection (separation of posterior

Fig. 24.53

capsule from the cortex and hydrodelineation

IX. Additional instruments for intraocular lens

(separation of cortex from the nucleus) in

implantation

phacoemulsification and manual SICS. This cannula

For IOL implantation, the cataract surgery set should

is attached to the syringe carrying irrigating fluid.

contain the following basic additional instruments:

For hydrodissection its tip is introduced beneath the

1. IOL holding forceps (Fig. 24.54). It is a spring-

anterior capsular margin after capsulorhexsis and fluid

action forceps with short, blunt and curved blades

is injected to obtain subcapsular dissection.

having smooth edges and tips with plateform (no

teeth or serrations). Use: To hold optic of non-foldable

PMMA IOL during implantation.

Fig. 24. 54

Fig. 24.57

2. Kelman-McPherson forceps (Fig. 24.55). These

5. Chopper (Fig. 24.58). The chopper is a fine

are fine forceps with bent limbs. Uses: (i)To hold the

instrument resembling sinskey hook in shape. The

superior haptic of IOL during its placement. (ii) To

inner edge of the bent tip is cutting and may have

tear off the anterior capsular flap in ECCE. (iii) Can be

different angles. Uses. It is used to split or chop the

used for suture tying.

nucleus into smaller pieces and also for nuclear

manipulation in phacoemulsification surgery.

Fig. 24. 55

Fig. 24.58

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

583

6. Ring capsule polisher or posterior capsule

2. Lid spatula (Fig. 24.63). It is a simple metal plate

polishing curette (Fig. 24.59). It consists of a long

having slightly convex surfaces at either end. Uses:

handle and a bent slender neck. The tip of the

To protect the globe and support the lid during

instrument has a tiny circular ring. Uses. It is used to

entropion, ectropion, ptosis and other lid surgeries.

clear and polish the posterior lens capsule to make it

more clear in the extracapsular cataract surgery. It is

specially used when a plaque or sticky cortex is

adhered to the posterior capsule.

Fig. 24.63

XII. Additional instruments for lacrimal sac

Fig. 24.59

surgery (DCT and DCR)

1. Punctum dilator (Nettleship’s) (Fig. 24.64). It has

X. Additional instruments for glaucoma surgery

a cylindrical corrugated metal handle with a conical

1. Scleral punch (Fig. 24.60). It is of the shape of

pointed tip. Uses: To dilate the punctum and

corneal scissors with spring action mechanism. Its

canaliculus during syringing, probing, dacryocysto-

one blade is sharp and thick which presses into the

graphy, DCT and DCR procedures.

second blade which is a hollow rectangular frame.

Use: To perform punch sclerectomy during glaucoma

surgery.

Fig. 24.64

2. Lacrimal probes (Bowman’s) (Fig. 24.65). These

are a set of straight metal wires of varying thickness

(size 0-8) with blunt rounded ends and flattened

central platform. Uses: (i) To probe nasolacrimal duct

in congenital blockage. (ii). To identify the lacrimal

sac during DCT and DCR operations.

Fig. 24.60

2. Kelley’s punch (Fig. 24.61). It is used to enlarge

the bony opening during DCR operation by punching

the bone from margins of the opening. Carelessness

Fig. 24.65

during this step can cause accidental damage to the

3. Lacrimal cannula (Fig. 24.66). It is a long curved

nasal mucosa and the nasal septum. Uses. It is used

to perform punch sclerectomy in conventional as well

hypodermic needle with blunt tip. Uses: (i) For

as sutureless trabeculectomy operation.

syringing the lacrimal passages. (ii) As AC cannula

for putting air or balanced salt solution in the anterior

chamber during intraocular surgery.

Fig. 24.61

XI. Additional instruments for lid surgery

Fig. 24.66

1. Chalazion scoop (Fig. 24.62). It has a small cup

with sharp margins attached to a narrow handle. Use:

4. Bone punch (Fig. 24.67). It consists of a stout

To scoop out contents of the chalazion during incision

spring handle and two blades attached at right angle.

and curettage.

The upper blade has a small hole with a sharp cutting

edge. The lower blade has a cup-like depression. Uses:

It is used to enlarge the bony opening during DCR

Fig. 24.62

584

Comprehensive OPHTHALMOLOGY

operation by punching the bone from margins of the

opening. Carelessness during this step can cause

accidental damage to the nasal mucosa and the nasal

Fig. 24.71

septum.

XIII. Additional instruments for enucleation and

evisceration

1. Optic nerve guide (enucleation spoon) (Fig. 24.72).

It is a spoon-shaped instrument with a central

cleavage. Use: To engage the optic nerve during

enucleation.

Fig. 24.67

Fig. 24.72

5. Chisel (Fig. 24.68). It consists of a blade having a

sharp-cutting straight edge with one surface bevelled.

2. Evisceration spatula (Fig. 24.73). It consists of a

It has a long and stout handle. Use: To cut the bone

small but stout rectangular blade with slightly convex

during DCR and orbitotomy operations.

surface and blunt edges attached to a handle. Use:

To separate out the uveal tissue from the sclera during

evisceration operation.

Fig. 24.68

6. Hammer (Fig. 24.69). It is a small steel hammer

Fig. 24.73

attached to a corrugated handle. Use: To hammer the

chisel during DCR and orbitotomy operations.

3. Evisceration curette (Fig. 24.74). It consists of an

oval or rounded shallow cup with blunt margins

attached to a stout handle. Use: To curette out the

intraocular contents during evisceration operation.

Fig. 24.69

Fig. 24.74

7. Lacrimal sac dissector and curette (Fig. 24.70). It

is a cylindrical instrument, one end of which is a blunt-

STERILIZATION, DISINFECTION

tipped dissector and the other end is curetted. Use:

In lacrimal sac surgery.

AND FUMIGATION

STERILIZATION AND DISINFECTION

It is a process which kills or removes all micro-

organisms including bacterial spores from an article,

Fig. 24.70

surface or medium. It must be differentiated from

8. Bone gouge (Fig. 24.71). It consists of a stout

disinfection which destroys pathogenic micro-

metallic handle, one end of which is longitudinally

organisms but does not kill or remove spores.

scooped. The edges of the scoop are sharp. Use: To

Sterilization can be accomplished by physical

smoothen the irregularly cut margins of the bone by

agents (viz. sunlight, heat, filtration and radiation)

nibbling small projecting bone and in DCR operation

and chemical agents (such as alcohols, aldehydes,

and in orbitotomy operation.

halogens, phenol, surface acting agents and gases).

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

585

Methods

(B) Chemical sterilization

Savlon. It comprises of cetavlon or cetrimide and

(A) Heat sterilization

chlorhexidine. Cetavlon is a surface active agent

Both dry and moist heat can be used.

and chlorhexidine is a phenol. It is active against

most gram-positive organisms. It is used for

Dry heat sterilization methods

cleaning/preparation of skin. Scissors, catheters,

1. Flaming. It can be used to sterilize points of

knives etc. may also be sterilized with it.

forceps, hypodermic needles, tips of AC cannula

Spirit (95% alcohol). It kills bacteria and spores,

and scraping spatulas. The instrument is held in

but not viruses. It is mostly used with savlon.

a bunsen flame till it becomes red hot.

Methylated spirit. It is

70 percent isopropyl

2. Incineration. It is used to destroy soiled

alcohol. Schiotz tonometer can be sterilized by it.

dressings, beddings and pathological materials.

Formaldehyde

i. Formalin. 10 percent solution of formalin has

3. Hot air oven. It is the most commonly used

a marked bactericidal, sporicidal and some

method of sterilization by dry heat. It kills bacteria,

viricidal activity. It is suitable for cryoextractor

spores and viruses. This method is employed to

probes and heat sensitive instruments.

sterilize instruments like forceps, scissors,

ii. Formaldehyde gas. It may be used for

scalpels, glass syringes, glassware etc. The item

fumigating wards, sick rooms and laboratories.

must be double wrapped and kept at 150° C for

But this gas is irritant and toxic when inhaled.

2 hours.

Glutaraldehyde (2%). It is available as ‘Cidex’

solution. It has a special activity against tubercle

Moist heat sterilization methods

bacilli, fungi and viruses. It is mostly used for

1. Boiling. It kills bacteria and viruses. Heavier

sterilising endoscopes because it has no damaging

metallic ophthalmic instruments, e.g., Bard-Parker

effect on the lenses. It can be safely used for

handles, lid guards etc. can be sterilized by boiling

catheters, face-masks, anaesthetic tubes and metal

in water for 30 minutes. This method, however,

instruments. However, it is not suitable for silicone

blunts the cutting instruments.

tubing. It is specially used to sterilize sharp

instruments, as it does not affect the sharpness.

2. Steaming. It kills most bacteria and viruses, but

In three hours, the instruments are free of

not spores. The instruments are placed on a shelf

pathogens and spores. Instruments should be

above the level of water and steamed for about

thoroughly washed with sterile distilled water

30 minutes. Most of the metallic instruments e.g.,

before use.

scissors and knives can be sterilized by this

Hydrogen peroxide. A

3 percent solution of

method.

H₂O₂ is used for sterilisation of applanation

3. Autoclaving (steam under pressure).It is the most

tonometers, prisms and ophthalmoscopy lenses.

widely used method for sterilization. It is based

It is specially active against AIDS and herpes

on the principle that at boiling point of water, the

viruses.

vapour pressure equates the atmospheric

Ethylene oxide gas: It is a highly inflammable

pressure. So, if the pressure is increased, boiling

gas and is usually mixed with an inert gas like

nitrogen or carbon dioxide. It denatures the protein

point tends to rise, which increases the

molecules. It is effective against almost all bacteria,

penetrating power of the steam.

spores and viruses. Goniotomy lenses, indirect

Autoclaving at 121° C under 15 1b/in² pressure for

ophthalmoscopy lenses, DCR tubings and

20 min. or at 116° C under 10 1b/in² pressure for 40

cryoprobes can be sterilized with it.

min. kills bacteria, spores and viruses. This method

Acetone. Use of acetone is a quick and cheap

is suitable for sterilizing various instruments, linen,

method of sterilising instruments. Instruments

glass wares, rubber goods, gowns, towels, gloves

should be kept in acetone for 5 minutes and then

dressings and eyedrops.

thoroughly washed with sterile water before use.

586

Comprehensive OPHTHALMOLOGY

RELATED QUESTIONS

1. Ionising radiations: These include X-rays,

gamma-rays, cosmic rays. They are highly lethal

ANAESTHESIA FOR OCULAR SURGERY

to DNA and thus kill all types of micro-organisms.

They can penetrate solids and liquids without

How topical ocular anaesthesia is achieved? What

raising the temperature appreciably

(cold

are its indications?

Topical ocular anaesthesia is achieved by instillation

sterilisation). They are used for sterilizing plastic

of 2 to 4% xylocaine or 1% amethocaine, 4 times every

syringes, swabs, catheters, tubings etc.

4 minute.

2. Non-ionising radiations: They act as a form of

Indications

hot air sterilization since they are absorbed as

For minor procedures like removal of corneal

heat. They include the infrared rays which is

foreign body, removal of stitches etc.

used for rapid mass sterilization of disposable

Along with retrobulbar block.

syringes.

Recently, phacoemulsification operation is being

Fumigation of operation theatre

done under topical anaesthesia.

Fumigation refers to disinfection of the operating

What are various techniques of facial block

room by exposure to the fumes of a vaporised

anaesthesia?

disinfectant. Formaldehyde is an effective agent

Van Lint’s block: Terminal branches of facial

commonly used to sterilize the operating room. For

nerve are blocked by injecting 2.5 ml of anaesthetic

optimum disinfection, formaldehyde fumigation is

solution in deeper tissues just above the eyebrows

recommended fortnightly as a routine and at the end

and just below the inferior orbital margin.

of an operating session of a grossly infected case.

O’Brien’s block: Facial nerve is blocked at the

neck of mandible

Method of fumigation involves following steps:

Nadbath blcok: Facial nerve is blocked near the

Cleaning and scrubing of the operating room is

stylomastoid foramen.

done thoroughly and the floor is carbolised.

Atkinson’s block: Only superior branches of facial

Sealing of all the aperatures in the room is done

nerve are blocked by an injection at the inferior

prior to fumigation leaving only one door open.

margin of zygomatic bone.

Generation of formaldehyde is done by addition

Where injection is made for retrobulbar block?

of 150gm of potassium permanganate (KMnO₄)

For a retrobulbar block, 2 ml of 2% xylocaine is injected

to 280ml of formalin in a steel bucket for every

into the muscle cone.

1000 cubic feet of room volume. Alternatively,

What are the effects of retrobulbar block ?

500 ml of 40% formaldehyde in one litre of water

Ciliary nerve and ciliary ganglion block

is put into an electric boiler or a large bowl placed

Ocular akinesia

on a electric hot plate with safety cut-out when

Ocular anaesthesia and analgesia

boiling dry.

Dilatation of the pupil

Closure and sealing of the door is done quickly.

Ocular hypotony

After formaldehyde vapour is generated the room

Enumerate complications of retrobulbar block.

should be left closed for 24 to 48 hours.

Retrobulbar haemorrhage

Neutralization of formaldehyde is then carried

Globe perforation

out with ammonium solution left in the operating

Optic nerve injury

room for a few hours. One litre of ammonium

Extraocular muscle palsies

solution plus one litre of water is required to

What is the technique of peribulbar block?

neutralize every litre of 40% formaldehyde used.

An anaesthetic solution, 6 to 9 ml (a mixture of 2%

Replacement of left out formalin with air.

xylocaine and 0.5-0.75% bupivacaine) in a ratio of 2:1

Subsequently the room doors may be opened for

with hyaluronidase 5 I.U./ml with or without

a short period or the air-conditioning switched

adrenaline 1:1 lac is injected into the peripheral orbital

on to replace the formalin with air.

space.

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

587

What are the advantages of peribulbar block?

2. Posterior chamber IOL can be implanted after

No separate facial block is required.

ECCE, while it cannot be implanted after ICCE.

Complications associated with retrobulbar block

3. Postoperative vitreous-related problems (such as

are almost eliminated.

herniation in anterior chamber, pupillary block

and vitreous touch syndrome) associated with

OPHTHALMIC INSTRUMENTS AND EYE

ICCE are not seen after ECCE.

OPERATIONS

4. Incidence of postoperative complications such

Usually a student is asked to describe a particular

as endophthalmitis, cystoid macular oedema and

retinal detachment is much less after ECCE as

ophthalmic instrument in reference to following

compared to that after ICCE.

aspects:

Identification of the instrument

What are the advantages of ICCE over ECCE?

Methods of its sterilization

1. The technique of ICCE as compared to ECCE is

Uses of the instrument

simple, cheap, easy and does not need sophisti-

cated microinstruments.

2. Postoperative opacification of posterior capsule

OPERATIONS FOR CATARACT EXTRACTION

is seen in a significant number of cases after

Name the instruments required for intracapsular

ECCE. No such problem is there after ICCE.

cataract extraction.

3. ICCE is less time consuming and hence more

The instruments required for intracapsular cataract

useful than ECCE for mass scale operations in

extraction include superior rectus holding forceps,

eyecamps.

Stevens’ needle holder, artery forceps, plane forceps,

Name the methods of lens delivery in

curved ringed scissors, heat cautery or wet-field

intracapsular cataract extraction.

cautery, razor-blade fragment holder, corneo scleral

1. Indian Smith method

suturing forceps, corneoscleral section enlarging

2. Cryoextraction

scissors, iris forceps, deWecker’s iridectomy

3. Capsule forceps method

scissors, lens spatula, lens hook, anterior chamber

4. Irisophake method

cannula, iris repositor, spring action fine needle holder.

5. Wire-vectis method for subluxated lens

These instruments form the basic intraocular

Name the different techniques of extracapsular

surgery set.

catract extraction.

1. Discission or needling

Name the additional instruments required for

2. Linear extraction or curette evacuation

extracapsular cataract extraction.

3. Modern extracapsular cataract extraction (ECCE)

Cystitome, Vannas’ scissors, McPherson’s forceps,

4. Lensectomy

two-way irrigation-aspiration cannula; posterior

5. Phacoemulsification

capsule polisher.

What are the main steps of lens removal in ECCE

Name (pick up) the additional instruments required

operation ?

for an intraocular lens implantation.

1. Anterior capsulotomy

Anterior chamber cannula for injecting viscoelastic

2. Removal of nucleus

substance, intraocular lens (implant) holding forceps

3. Aspiration of the cortical lens matter

and intraocular lens dialer.

Name the techniques of anterior capsulotomy

Name the two main techniques of cataract

1. Can-opener technique

extraction.

2. Linear capsulotomy (envelope technique)

1. Intracapsular cataract extraction (ICCE)

3. Continuous circular capsulorhexis (CCC)

2. Extracapsular cataract extraction (ECCE).

What is phacoemulsification ?

What are the advantages of ECCE over ICCE?

Phacoemulsification is a technique of extracapsular

1. Extracapsular cataract extraction is a universal

cataract extraction in which after the removal of

operation and can be performed at all ages, except

anterior capsule (by capsulorhexis), the lens nucleus

when zonules are not intact. While ICCE cannot

is emulsified and aspirated by the probe of a

be performed below 40 years of age.

phacoemulsification machine.

588

Comprehensive OPHTHALMOLOGY

What are the advantages of phacoemulsification

Name the IOL-related complications.

over the conventional ECCE operation?

1. Malpositions of the IOL, e.g., inferior subluxation

1. Corneoscleral incision required is very small (3

(Sunset syndrome), superior subluxation (Sunrise

mm). Therefore, sutureless surgery is possible

syndrome), dislocation of IOL in the vitreous

with a self-sealing scleral tunnel incision

cavity (lost lens syndrome)

2. Early visual rehabilitation of the patient

2. Toxic lens syndrome (IOL-induced iritis).

3. Very less astigmatism

What are the advantages of an IOL implantation

What are the main types of intraocular lenses

over spectacle correction of aphakia?

(IOL)?

1. No magnification of the object.

The major classes of IOL based on the method of

2. No problem of anisometropia in uniocular aphakia.

fixation in the eye are as follows:

3. Elimination of aberrations and prismatic effect of

1. Anterior chamber IOL, e.g., ‘Kelman multiflex IOL’

thick glasses.

2. Iris supported lenses, e.g., Singh-Worst’s iris

4. Wider and better field of vision.

claw lens

5. Cosmetically more acceptable.

3. Posterior chamber lens

What is postoperative management of cataract

Name the absolute contraindications of an IOL

operation ?

implantation.

1. The patient is asked to lie quietly upon his/her

1. Proliferative diabetic retinopathy

back for about three hours and advised to take

2. Recurrent uveitis

nil orally.

When and who preformed the first successful

2. For mild to moderate postoperative pain, injection

intraocular implant operation ?

diclofenac sodium

(Voveran) may be given

Harold Ridley, a British ophthalmologist, performed

intramuscularly.

the first IOL implantation on November 29, 1949.

3. In the morning after about 24 hours of operation,

Name a few perioperative complications of

bandage is removed and the eye is inspected

cataract operation.

thoroughly for any postoperative complication.

1. Injury to cornea (Descemet’s detachment)

Under normal circumstances, eye is redressed

2. Accidental rupture of the lens capsule

with one drop of 1 percent cyclopentolate, one

3. Vitreous loss

drop of antibiotic and steroid drops and ointment.

4. Expulsive choroidal haemorrhage

Daily dressing and bandaging continues for about

3 to 4 days and after that dressing is removed

Name some early postoperative complications of

cataract extraction.

and tinted glasses are advised.

1. Hyphaema

4. Antibiotic steroid eyedrops are continued for

2. Iris prolapse

four times, three times, two times and then once

3. Striate keratopathy

a day for 2 weeks each.

4. Flat (shallow) anterior chamber

5. After 4 to 6 weeks of operation, corneo-scleral

5. Bacterial endophthalmitis

sutures are removed.

6. Final spectacles are prescribed after about 8 weeks

What are delayed complications of cataract

of operation

extraction?

1. Cystoid macular oedema (CME)

What do you understand by primary and

2. Retinal detachment (RD)

secondary IOL implantation ?

3. Epithelial ingrowth

Primary IOL implantation refers to the use of IOL

4. After-cataract

during surgery for cataract, while secondary IOL is

implanted to correct aphakia in a previously operated

What are the types of after-cataract ?

eye.

1. Thin membranous after-cataract

(thickened

posterior capsule).

How will you calculate the power of posterior

2. Dense membranous after-cataract

chamber IOL to be implanted ?

3. Soemmerring’s ring after-cataract

The power of the IOL to be implanted can be

4. Elschnig’s pearls

calculated using keratometry and A-scan ultrasound.

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

589

SRK formula commonly employed to calculate IOL

Early cases of acute congestive glaucoma, i.e.,

power is as follows:

when peripheral anterior synechiae are formed in

P = A - 2.5L - 0.9K; where P = IOL power in dioptres,

less than 50 percent of angle

A = specific constant of the IOL, L= axial length of

As a prophylaxis in other eye of the patient

the eyeball in mm and K= average keratometric

What are filtration operations for glaucoma?

reading.

In filtration operations, passage is made for the

IRIDECTOMY OPERATION

drainage of aqueous humour into the subconjunc-

tival space. Trabeculectomy is presently the most

What is iridectomy and what are its types?

frequently performed filtration surgery. Other filtration

Iridectomy is an abscission of a part of the iris. It is of

operations which are now performed sparingly

the following types:

include: Elliot’s sclerocorneal trephining, punch

Peripheral iridectomy

sclerectomy, iridencleisis, Scheie’s thermal

Key-hole iridectomy

sclerostomy and cyclodialysis.

Broad or sector iridectomy

What are the indications of trabeculectomy

What are the indications of iridectomy operation?

operation?

1. Abscission of the prolapsed iris

1. Primary angle-closure glaucoma with peripheral

2. For optical purposes (optical iridectomy)

anterior synechiae involving more than half of

3. As a part of cataract operation

the angle.

4. As a part of glaucoma operation

5. For removal of foreign body, cyst or tumour of

2. Primary open-angle glaucoma.

the iris

3. Congenital and development glaucoma where

6. In iris bombe formation (annular synechiae)

trabeculotomy and goniotomy fail.

4. Selective cases of secondary open as well as

What is iridotomy and how is it performed?

narrow-angle glaucoma.

Iridotomy means just incising a part of the iris. It can

be performed by two methods:

What are the advantages of trabeculectomy over

Surgical iridotomy

other filtration operations ?

Laser iridotomy

1. Incidence of postoperative shallow or flat anterior

What are indications of iridotomy operation?

chamber is very less.

1. As a part of cataract surgery

2. Incidence of postoperative hypotony is very low.

2. Laser iridotomy for primary narrow-angle

3. Chances of postoperative infection through the

glaucoma

filtration bleb are low.

3. Four-dot iridotomy for iris bombe

4. Quality of filtration bleb formed is good.

What is Seton operation ?

SURGICAL PROCEDURES FOR GLAUCOMA

In this operation, a valvular synthetic tube is

Name the various surgical procedures for

implanted which drains the aqueous humour from the

glaucoma.

anterior chamber into the subconjunctival space.

1. Peripheral iridectomy

It is performed for neovascular glaucoma and

2. Goniotomy

intractable cases of primary and other secondary

3. Trabeculotomy

glaucomas where medical treatment and conventional

4. Filtration operations

filtration surgery fail.

5. Seton operation (glaucoma valve operation)

6. Cycloablative procedures

What are cycloablative procedures ?

In these procedures, ciliary epithelium is destroyed

Peripheral iridectomy operation is performed for

which type of glaucoma?

to control the intraocular pressure. These procedures

In primary angle-closure glaucoma during:

are used for absolute glaucoma. Commonly employed

Prodromal stage

cycloablative procedures include: cyclocryopexy,

Stage of constant instability

cyclophotocoagulation and cyclodiathermy.

590

Comprehensive OPHTHALMOLOGY

Cyclodialysis operation is useful in which type of

LASERS AND CRYOTHERAPY IN

glaucoma?

OPHTHALMOLOGY

Glaucoma in aphakes

What are the properties of laser light?

Monochromaticity

ENUCLEATION AND EVISCERATION

Coherence

OPERATIONS

Collimation

What is enucleation operation ?

Name the different types of lasers and their

It is complete excision of the eyeball.

mechanism of action.

Enumerate indications of enucleation.

Type of laser

Mechanism of action

Absolute indications are:

Argon

Photocoagulation

Retinoblastoma

Krypton

Photocoagulation

Malignant melanoma

Diode

Photocoagulation

Relative indications are:

Nd-YAG

Photocoagulation

Painful blind eye due to absolute glaucoma

Excimer

Photoablation

Painful blind eye due to endophthalmitis

Enumerate uses of argon/diode laser.

Mutilating ocular injury

In glaucoma

Phthisis bulbi

1. Laser trabeculoplasty for primary open-angle

Anterior staphyloma

glaucoma.

What precautions should be taken while

2. Laser goniopuncture for developmental glaucoma.

performing enucleation in a patient with

3. Laser iridotomy for narrow-angle glaucoma.

retinoblastoma?

4. Cyclophotocoagulation for absolute glaucoma.

During enucleation the longest possible piece of optic

In lesions of retina

nerve should be excised.

1. Diabetic retinopathy

2. Eales’ disease

What is evisceration operation?

3. Coats’ disease

It is removal of the contents of the eyeball leaving

4. Sickle-cell retinopathy

behind the sclera. Frill evisceration is preferred over

5. Exudative age-related macular degeneration

simple evisceration. In it, only about 3 mm frill of the

sclera is left around the optic nerve.

What are the therapeutic uses of Nd-YAG laser?

1. Capsulotomy for thickened posterior capsule

What are the indications of evisceration?

2. Membranectomy for pupillary membranes

Panophthalmitis

What are therapeutic applications of excimer

Expulsive choroidal haemorrhage

laser?

Bleeding anterior staphyloma

1. Photorefractive keratectomy (PRK) for correction

How can the cosmetic appearance be improved

of myopia and hypermetropia.

after enucleation or evisceration operation?

2. Phototherapeutic keratectomy (PTK) for corneal

For best results, an orbital implant should be

diseases such as band-shaped keratopathy.

implanted at the time of surgery and an artificial eye

Describe the laser treatment for diabetic

of plastic should be worn after about 2 weeks of

retinopathy.

surgery. A delay in the use of artificial eye may lead

Photocoagulation by argon or diode laser is employed

to a contracted socket.

as follows:

1. Panretinal photocoagulation (PRP) is indicated

OPERATIONS ON EYELIDS

in severe cases of preproliferative and proliferative

For important questions related to eyelid operations

diabetic retinopathy.

see page 526-531

2. Focal laser burns are applied in the centre of the

hard exudate’s ring in focal exudative

LACRIMAL APPARATUS OPERATIONS

maculopathy.

Questions related to operations on the lacrimal

3. Grid pattern laser burns are applied in diffuse

apparatus are described on page 531-533

exudative maculopathy.

OPHTHALMIC INSTRUMENTS AND OPERATIVE OPHTHALMOLOGY

591

What do you mean by cryopexy ?

for warts and molluscum contagiosum,

(iii)

Cryopexy means to produce tissue injury by

cryotherapy for basal cell carcinoma and

application of extremely low temperature (-100°C

haemangioma

-40°C). This is achieved by a cryoprobe from a cryo-

2. Conjunctiva: Cryotherapy for hypertrophied

unit.

papillae of vernal catarrh

On what principle is the working of a cryoprobe

3. Lens: Cryoextraction of the cataractous lens

based?

Working of a cryoprobe is based on the Joule-

4. Ciliary body: Cryclocryopexy for absolute

Thompson principle of cooling.

glaucoma and neovascular glaucoma

Which gas is used in a cryo-machine?

5. Retina: (i) cryopexy is widely used for sealing

The cryounit uses freon, nitrous oxide or carbon-

retinal breaks in retinal detachment,

(ii)

dioxide gas as a cooling agent.

prophylactic cryopexy to prevent retinal

detachment in certain prone cases, (iii) anterior

Enumerate the applications of cryo in

ophthalmology?

retinal cryopexy (ARC) for neovascularization and,

1. Lids: (i) cryolysis for trichiasis, (ii) cryotherapy

(IV) cryotreatment of retinoblastoma.

Index

conjunctiva, 51

cornea, 89

Abnormal retinal correspondence, 320

extraocular muscles, 313

Abrasion, corneal, 404

eyeball, 3

Acanthamoeba keratitis, 106

iris, 133

Accommodation, 39-43

lacrimal apparatus, 363

amplitude, 41

lens, 167

anomalies, 41

lids, 339

insufficiency of, 42

optic disc, 249, 287

paralysis of, 42

optic nerve, 287

spasm of, 43

ora serrata, 250

Acetazolamide, 426

orbit, 377

Achromatopsia, 305

retina, 249

Acne rosacea, keratitis, 108

sclera, 127

Acquired immune

uveal tract, 133

deficiency syndrome (AIDS), 436

visual pathway, 287

Acute multifocal placoid

vitreous, 243

pigment epitheliopathy, 160

Angiography, fluorescein, 487

Acyclovir, 421

Angiomatosis, retinae, 285

Adaptation-dark, 15

Angle kappa, 27, 321

Adenocarcinoma, pleomorphic, 376

Angular conjunctivitis, 61

Adie's pupil, 293

Aniridia, 137

Age-related cataract, 175

Aniseikonia, 39

corneal degenerations, 115

Anisocoria, 293

macular degeneration, 274

Anisometropia, 38

Amaurosis, 306

Ankyloblepharon, 354

Amblyopia,

Ankylosing spondylitis, 157

congenital, 306

Annular scleritis, 129

ethyl alcohol, 296

Annular synechia, 144

ex anopsia, 319

Anomaloscope, Nagel's, 305

hysteria, 307

Anomalous retinal

methyl alcohol, 296

correspondence, 320

quinine, 297

Anterior chamber

tobacco, 296

antomy of, 4

Amblyoscope major, 329

angle, 205

Ametropia, 28

examination, 472

Aminoglycosides, 419

flat or shallow postoperative, 200

Amoxycillin, 419

Anterior ischaemic optic

Amphotericin B, 422

neuropathy, 297

Ampicillin, 419

Antibacterial agents, 418

Anaesthesia, ocular surgery, 571-573

Antifungal agents, 422

Anatomy of

Antiglaucoma drugs, 423-427

angle of anterior chamber, 205

Antiviral agents, 420

anterior chamber, 4

Aphakia, 31, 174

ciliary arteries, 135-136

Applanation tonometer, 480

ciliary body, 134

Aqueous flare, 143

594

Comprehensive OPHTHALMOLOGY

Aqueous humour, 207

Blindness

drainage, 208

cataract, 446, 452

flare, 143

causes, 445

nature and formation/

childhood 447, 452

production, 207

colour, 303

Aqueous veins, 207

corneal, 453

Arcus senilis and juvenilis, 115

cortical, 306

Argon laser trabeculoplasty, 223

definition, 443

Argyll Robertson pupil, 293

glaucoma, 452

Argyrosis, 85

hysterical, 307

Arlt's line, 64

magnitude, 444

Astigmatic fan, 556

prevention, 445-457

Astigmatism, 36

snow, 111

against the rule, 36

Blue sclera, 131

bioblique, 36

Bowman's membrane, 80

compound hypermetropic, 37

Brown's syndrome, 335

compound myopic, 37

Bruch's membrane, 135

irregular, 38

Buphthalmos, 212

mixed, 37

Burns

regular, 36

chemical, 414

simple hypermetropic, 36

thermal, 415

simple myopic, 36

Burow's operation, 350

with the rule, 36

Busacca's nodules, 144, 473

Atopic kerato-conjunctivitis, 76

Atropine, 98, 146, 550

Axes of the eye, 27

Calcific corneal degeneration, 115

Campimetry, 482

Canal of Cloquet, 243

Basal cell carcinoma

Canal of Schlemm, 207

conjunctiva, 87

Candidiasis uveitis in, 159

lids, 360

Capsulotomy, 201

Band keratopathy, 115

anterior, 189

Behcet's disease, 156

posterior, 202

Bell's phenomenon, 357

Carbonic anhydrase inhibitors, 426

Benedikt's syndrome, 310

Carcinoma

Bergmester's papilla, 253

of conjunctiva, 87

Berlin's oedema, 406

of lids, 360-361

Beta-adrenergic blockers, 425

Caruncle, 53

Binocular loupe, 544

Cataract, 170-202

Binocular vision, 318

acquired, 175

anomalies of, 318

aetiological classification of, 170

grades of, 318

after, 201

Birdshot retinochoroidopathy, 161

anterior capsular, 171

Bitot's spots, 434

black, 178

Bjerrum's

capsular, 171

scotoma, 219

complicated, 181

screen, 482

concussion, rosette-shaped, 405

Blepharitis, 344

congenital, 170

squamous, 344

coronary, 173

ulcerative, 344

cupuliform, 176

Blepharophimosis syndrome, 356

developmental, 170

Blepharospasm, 355

diabetic, 181

INDEX

595

electric, 182

haemorrhage, expulsive, 199

extraction, extracapsular, 185, 187

melanoma, 163

galactosaemic, 181

rupture, 406

implant surgery of, 195

Choroiditis, 148

intracapsular extraction of, 185, 187

anterior, 149

incipient, 176

central, 149

intumescent, 177

diffuse, 149

irradiation, 182

disseminated, 149

lamellar, 172

juxta papillary, 149

mature, 177

syphilitic, 155

metabolic, 181

treatment, 150

morgagnian, 177

tubercular, 155

morphological classification of,170

Chromatic aberrations, 27

myotonia dystrophica, 176

Ciliary body, 134

nuclear, 178

anatomy of, 134

parathyroid tetany, 181

injury, 404

phacoemulsification, 186, 191

partial destruction of, 240

polar, 171

tumours of, 165

posterior subcapsular, 170

Ciliary muscle, 135

punctate, 173

Ciliary processes, 135

reduplicated, 171

Ciliary staphyloma, 132

rosette, 405

Circle of least diffusion, 26

secondary, 201

Closed angle glaucoma, 225-231

senile, 175

Coat's disease, 266

SICS, 185-186, 189

Colloid bodies, 274

sunflower, 181

Coloboma

toxic, 182

iris, 137

traumatic, 405

lens, 204

treatment of, 174, 183

lid, 342

unilateral, treatment of, 174

optic disc, 252

zonular, 172

uveal tract, 137

Cataracta brunescens, 178

retina, 252

Cauterisation, corneal ulcer, 99

Colour

Cavernous sinus thrombosis, 387

blindness, 303

Central retinal artery occlusion,255

sense, 17

Central serous retinopathy, 272

vision, 17, 303

Cephalosporins, 419

testing of, 305

Chalazion, 346

Commotio retinae, 406

clamp, 347, 581

Concretions, 64, 82

Chalcosis, 410

Cones, 250

Chemical injuries, 414

Confrontation test, 482

Chemosis, conjunctival, 83

Conical cornea, 119

Cherry-red spot, 255, 406, 478

Conjunctiva/conjunctival

Chiasmal syndrome, 310

anatomy of, 51

Chlamydia, 62

chemosis, 83

Chloroquine maculopathy, 271

congestion,83

Choriocapillaris, 135

cysts, 85

Choroid, 135

degenerative conditions, 80

Choroidal

discoloration of, 85

atrophy, 162

ecchymosis, 83

coloboma, 137

examination, 468

degeneration, 162

hyperaemia, 83

detachment, 200

oedema, 83

596

Comprehensive OPHTHALMOLOGY

pinguecula, 80

sensitivity, 471

pterygium, 80

staining, 472

tumours, 86

vascularization, 122

xerosis, 84, 434

xerosis, 434

Conjunctivitis

Corneal ulcer, 92

acute haemorrhagic, 69

bacterial, 92

acute serous, 69

complications, 97

allergic, 73

dendritic, 102

atopic, 76

fungal, 100

angular, 61

healing, 94

bacterial, 55

hypopyon, 96

chlamydial,62

marginal, 99

follicular, 69

Mooren's, 109

giant papillary, 77

mycotic, 100

granulomatous, 79

perforation of, 97

inclusion, 68

serpiginous, 109

infective, 55

treatment of, 97

membranous, 59

viral, 101

muco-purulent, 56

Coronary cataract, 173

phlyctenular, 77

Cortical blindness, 306

purulent, 58

Corticosteroids, 428

pseudomembranous, 60

Cover test, 322, 327

simple chronic, 60

Craniofacial dysostosis, 383

vernal, 74

Craniosynostosis, 383

viral, 68

Cross-cylinder, 555

Consensual light reflex, 291

Cryotherapy, 431

Contact dermo-conjunctivitis, 79

Cryptophthalmos, 343

Contact lenses, 44

Cupping of disc

Contusional injuries, 403

glaucomatous, 216

Convergence

physiological, 216

insufficiency, 321

Cupuliform cataract,176

near point, 323

Cyclitis, 138

Corectopia, 137

Cyclocryopexy, 241

Cornea/corneal

Cycloplegia, 550

abrasion, 404

Cycloplegics, 98, 146, 550

anatomy, 89

Cyst,

congenital anomalies, 91

conjunctival, 85

degeneration, 114

tarsal, 346

dystrophies, 117

Cysticercus in conjunctiva, 86

epikeratophakia, 32

Cystoid macular oedema, 200, 273

examination, 470

Cytomegalovirus retinitis, 160, 253

facet, 122

fistula, 97

guttata, 118

inflammation, 91

Dacryo-adenitis, 375

keratoplasty, 124

Dacryocystectomy, 376

leucoma, 121

Dacryocystitis, 369-375

macula, 121

Dacryocystography, 368

nebula, 121

Dacryocystorhinostomy, 372

oedema, 121

conventional, 372

opacity, 121

endonasal, 373

perforation, 97

Dacryops, 376

physiology, 13, 90

Dalen-Fuch's nodules, 413

INDEX

597

Dalrymple's sign, 391

paralytic, 352, 353

Day-blindness, 303

senile, 351, 352

Defective vision

Electromagnet, 411

causes, 462

Electro-oculography, 489

Degenerations

Electroretinogram, 488

conjunctival, 80

Elschnig's pearls, 201

corneal, 114

Emmetropia, 28

macular 264

Encephalofacial angiomatosis, 285

retinal, 269-272

Endophthalmitis, 150

uveal tract, 161

Enophthalmos, 383

Demyelinating diseases, 310

Entropion, 348-351

cicatricial, 349

Dendritic ulcer, 102

Dermoids

congenital, 349

conjunctival, 86

senile, 349

spastic, 349

orbital, 393

Enucleation, 284

Dermo-lipoma, conjunctival, 86

Epicanthus, 342

Descemetocele, 97

Epidemic keratoconjunctivitis, 70

Descemet's membrane, 90

Epikeratophakia, 32

Detachment of

Epiphora, 12, 367

cilio-choroid, 200

Episcleritis, 128

retina, 275

Errors of refraction, 28-39

vitreous, 244

astigmatism, 36

Deuteranopia, 305

hypermetropia, 28

Development of eyeball, 5-11

myopia, 32

Deviation,

Esophoria, 321

primary, 331

Esotropia concomitant, 325

secondary, 331

Evisceration of eyeball, 154

Devic's disease, 310

Examination of eye

Diabetic

anterior chamber, 472

cataract, 181

conjunctiva, 468

retinopathy, 259

cornea, 470

Diffraction of light, 27

external eye, 466

Dilator pupillae, 134

field of vision, 481

Diplopia, 320, 331, 333, 463

fundus oculi, 477

Disciform

iris, 473

degeneration of macula, 264

lacrimal apparatus, 467

keratitis, 103

lens, 475

Distichiasis, 342

lid, 467

Doyne's honeycomb dystrophy, 478

oblique illumination, 543

Dry eye, 365

pupil, 473

Duane's retraction syndrome, 335

sclera, 470

Duochrome test, 556

Dystrophies

slit lamp, 544

corneal, 117

Excimer laser, 47

retinal, 268

Exophoria, 321

Exophthalmometry, 381

Exophthalmos (Proptosis) 379

bilateral, 381

Eales' disease, 254

endocrinal, 390

Ecchymosis, conjunctival, 83

pulsating, 381

Ectopia lentis, 202, 204

thyrotoxic, 391

Ectropion of lid, 351-353

thyrotropic, 391

cicatricial, 351, 353

unilateral, 380

598

Comprehensive OPHTHALMOLOGY

Exotropia, concomitant, 326

closed angle, 225-231

Exposure keratitis, 108

congenital / developmental, 212

Eyeball

infantile, 211

anatomy of, 3

inflammatory, 145, 233

development of, 5-11

juvenile, 211

dimensions of, 3

medical treatment of, 222

Eyebanking, 456

neovascular, 234

Eyecamps, 455

normal tension, 224

open angle, 214

operative treatment, 237

phacolytic, 181, 232

Faden operation, 335

phacomorphic, 181, 232

Far point of eye (punctum remotum), 41

pigmentary, 234

Farnsworth-Munsell test, 305

post-inflammatory, 145, 233

Fasanella-Servat operation, 358

primary, 214-225

Favre-Goldmann syndrome, 271

secondary, 231-237

Field of vision, 481

steroid induced, 235

Fincham's test, 228

Glaucomatocyclitic crisis, 160

Fixation, eccentric, 328

Glioma, optic nerve, 394

Fleischer's ring, 119

Goldmann three-mirror contact

Fluorescein angiography, 487

lens,546

Fluoroquinolones, 420

Gonioscopy, 546

Fogging method, 556

Goniotomy, 213

Follicular conjunctivitis, 69

Gonorrhoea conjunctivitis, 58, 71

Foreign body

Granulomatous

chalcosis, 410

conjunctivitis, 79

diagnosis, 410

uveitis, 141, 147

extraocular, 402

Grave's ophthalmopathy, 390

intraocular, 408

removal, 411

siderosis, 409

Form sense, 16

Haemangioma

Foster Fuch's spot, 34

choroidal, 162

Fovea centralis, 251

lids, 359-360

Foville's syndrome, 310

orbit, 393

Fuch's corneal dystrophy, 118

Haemorrhage

Fuch's heterochromic

choroidal, 199

iridocyclitis, 160

Fumigation, 586

expulsive, 199

Fundus

subhyaloid, 264

examination, 477

vitreous, 246

posterior fundus contact lens, 568

Halos

cataract, 178

glaucoma, 228

Hamarlopia, 303

Galactosaemia, cataract,181

Hand-Schuller-Christian disease,397

Giant papillary conjunctivitis, 77

Hassal-Henle bodies, 115

Glaucoma,

Head injury, ocular signs, 310

absolute, 231

Hemianopia, 290

acute congestive,229

binasal, 290

aphakic, 234

bitemporal, 290

capsulare, 234

homonymous, 290

chronic simple, 214

Hering's law, 316

INDEX

599

Herpes simplex, 101

sclera, 404, 408

Herpes zoster ophthalmicus, 103, 159

thermal, 415

Hess screen, 333

vitreous, 406

Heterochromia

Instruments, ophthalmic, 573-584

iridis, 137

Intraocular foreign bodies, 408

iridum, 137

Intraocular lens implantation, 195

Heterochromic iridocyclitis, 160

Intraocular pressure, 208

Heterophoria, 321

measurement of, 476, 479

Heterophoria, 321

Iridectomy, 589

esophoria, 321

for glaucoma, 237

exophoria, 321

optical, 122

technique of, 237

Histiocytosis-x, 396

Hordeolum

Irideremia (Aniridia), 137

externum, 345

Iridocorneal endothelial syndrome,237

Iridocyclitis, 141

internum, 347

acute, 141

Horner's syndrome, 356

chronic, 141

Hruby's lens, 568

granulomatous, 141, 146

Hutchinson's pupil, 311

heterochromic, 160

Hyperlacrimation, 367

hypertensive, 145, 233

Hypermetropia, 28

purulent, 150

Hypertensive retinopathy, 257

Iridodialysis, 404

Hyphaema, 199, 404

Iridodonesis, 31, 204, 473

Hypopyon ulcer, 96

Iridotomy, laser, 237, 431

Hysterical blindness, 307

Iris

anatomy, 133

anti-flexion, 404

atrophy, 161

Idoxuridine eye drops, 421

coloboma, 137

Inclusion conjunctivitis, 68

colour, 473

Infantile glaucoma, 211

examination, 473

Inflammations of

rupture, injury, 404

conjunctiva, 54

tumours, 166

cornea, 91

Iritis, 138

orbit, 384

Irradiation cataract, 182

retina, 253

Ishihara pseudo-isochromatic

sclera, 128

charts, 305

uvea, 138

Injuries, ocular

chemical, 414

choroid, 406

Jaeger's test types, 466

closed globe, 401, 403

Jaesche-Arlt operation, 350

contusions, 401

Jaw-winking synkinesis, 356

cornea, 404, 408

Jones dye test, 368

electrical, 416

Juvenile chronic arthritis

globe rupture, 407

uveitis in, 157

iris and ciliary body, 404

lens, 405, 408

mechanical, 401

open globe, 401

Kaposi's sarcoma, 437

optic nerve, 407

Kayser-Fleischer's ring, 410

perforating, 407

Keratectasia, 122

radiational, 416

Keratic precipitate, 142, 464

retina, 406

Keratitis, 91-114

600

Comprehensive OPHTHALMOLOGY

acanthamoeba, 106

development of, 8

acne rosacea, 108

dislocation, 24, 202

deep, 113

examination, 475

dendritic, 102

extraction, 187-202

disciform, 103

injury, 405, 408

exposure, 108

nucleus, 167

filamentary, 112

Lensectomy, 193

infective, 92

Lenses (optical), 23

interstitial, 113

cylinders, 25

metaherpetic, 103

spherical, 23

neuroparalytic, 107

Lenticonus, 204

non ulcerative, 110

Leucoma

phlyctenular, 78

adherent, 122

punctate, 110

corneal, 121

purulent, 92

Lids

syphilitic, 113

abnormalities, congenital, 342

Thygeson's, 112

anatomy, 339

ulcerative, 92

inflammations, 344

kerato-conjunctivitis sicca, 366

tumours, 359

Keratoconus, 119

Light reflex, 291, 474

Keratoglobus, 91, 120

Light sense, 15

Keratomalacia, 434

Low vision aids, 36, 269

Keratometer, 554

Keratopathy

band-shaped, 115

bullous, 119, 201

Macropsia, 150

filamentary, 112

Macular degeneration, 274

lipoid, 115

Macular disorders, 271

Keratoplasty, 124

Macular function tests, 184

Keratotomy, radial, 46

Macular oedema

Koeppe's nodule, 144, 473

cystoid, 200, 273

traumatic, 406

Madarosis, 66, 467

Maddox rod test, 322

Lacrimal apparatus

Maddox wing test, 323

anatomy and physiology,363-365

Malingering, 306

examination, 467

Mannitol, 427

gland, 363

Marcus Gunn pupil, 292

passage, 364

Marfan's syndrome, 202

syringing, 368

Marginal ulcer, 99

tumours, 376

Medullated nerve fibres, 253

Lagophthalmos, 354

Megalocornea, 91

Lasers in ophthalmology, 430

Meibomian glands, 341

Lasik, 47

Meibomitis, 345

Latanoprost, 427

Melanoma-malignant of

Lattice degeneration, 269

choroid, 163

Laurence-Moon-Biedl syndrome, 269

ciliary body, 165

Leber's disease, 295

conjunctiva, 88

Lens (crystalline)

iris, 166

anatomy, 167

lids, 361

capsule, 167

Membranous conjunctivitis, 59

coloboma, 204

Meningioma

congenital anomalies, 204

primary orbital, 395

cortex, 168

secondary orbital, 395

INDEX

601

Metamorphopsia, 150

Ocular ischaemic syndrome, 266

Methyl alcohol amblyopia, 296

Ocular movements, 315

Microcornea, 91

Opaque nerve fibres, 253

Micropsia, 150

Open angle glaucoma, 214

Mikulicz's syndrome, 376

Ophthalmia

Millard-Gubler's syndrome, 310

neonatorum, 71

Miosis, 474

nodosa, 80

Miotics, 423

Ophthalmic instruents, 573-584

Mittendorf dot, 253

Ophthalmoplegia

Molluscum contagiosum, 347

external, 333

Mooren's ulcer, 109

internal, 43

Morgagnian cataract, 177

internuclear, 333

Movements—ocular, 315

total, 333

Mucopurulent conjunctivitis, 56

Ophthalmoscopy, 564

Mucormycosis, orbital, 386

direct, 565

Multiple sclerosis, 310

distant—direct, 564

Muscles

indirect, 566

antagonists, 316

Optical aberrations, 27

extraocular, 313

Optic-atrophy, 301

synergists, 316

Optic chiasma, lesions, 288

Mycotic corneal ulcer, 100

Optic disc, 477

Mydriasis, 474

anatomy, 287

Mydriatics, 98, 146, 550

coloboma, 252

Myopia, 32

drusen, 252

glaucomatous cupping, 216

hypoplasia, 252

Optic Nerve, 287

Nagel's anomaloscope, 305

oedema, 298

Natamycin, 422

toxic amblyopias, 296

National programme for control of

tumours, 394

blindness (NPCB), 448

Optic neuritis, 294

Near point of eye (Punctum

Optic neuropathy, anterior 297

proximum), 41

Near reflex, 292

ischaemic, 297

Near vision,correction of, 557

Optic tract

Nebula, corneal, 121

anatomy of, 288

Neurofibromatosis, 285

lesions of, 290

Neuromyelitis optica, 310

Optic vesicle, 6

Neuroparalytic keratitis, 107

Opto-kinetic nystagmus, 336

Niemann-Pick's disease, 478

Optics

Night blindness, 303, 434, 463

geometrical, 19

Nodal point, 26

of the eye, 26

Non-steroidal anti-inflammatory agents, 428

Ora serrata, 250

Nystagmoid movements, 337

Orbit/orbital

Nystagmus, 336

anatomy, 377

cellulitis, 384-386

developmental anomalies, 383

exenteration, 399

Oblique muscles, 313

fracture, blow-out, 397

Occlusio pupillae, 145, 474

inflammations, 384

Ocular examination, 464-478

surgical spaces, 379

Ocular histoplasma syndrome, 158

tumours, 392-397

Ocular hypertension, 224

Orbitotomy, 399

602

Comprehensive OPHTHALMOLOGY

Pseudo-pterygium, 81

Pseudotumours of the orbit, 389

Pannus, trachomatous, 65

Pterygium, 80

Panophthalmitis, 153

Ptosis, 356

Papillitis, 294

Punctate keratitis, 110

Papilloedema, 298

Pupil/pupillary

Paralytic squint, 330

Adie's tonic, 293

Parinaud's oculoglandular syndrome, 79

Argyll-Robertson, 293

Pars plana vitrectomy, 247

contraction, 291

Pars planitis, 161

examination, 473

Penicillins, 419

membrane, persistent, 137

Perforating injuries, 407

miosis, 474

Perimeter/perimetry, 481

mydriasis, 474

automated, 483

reflexes, 291

manual, 482

Purkinje's images, 476

Periphlebitis retinae, 254

Persistent pupillary membrane, 137

Phacoanaphylactic uveitis, 160,181

Phacolytic glaucoma, 181, 232

Quinine amblyopia, 297

Phacoemulsification, 186, 191

Phakomatosis, 285

Phlyctenular

conjunctivitis, 77

Radial keratotomy, 46

keratitis, 78

Radiation cataract, 182

Photocoagulation, 263, 431

Rectus muscles, 313

Photo-ophthalmia, 111

recesion, 335

Photorefractive keratectomy (PRK),46

resection, 336

Photoretinitis, 271

Reduced eye, 26

Phthisis bulbi, 147

Refraction

Physiology of

determination, 547

cornea, 13, 90

errors of, 28

crystalline lens, 13, 168

objective, 547

tears, 364

subjective, 554

vision, 14

Refractive surgery, 46-49

Pigmentary retinal dystrophy, 268

Refractometry, 553

Pilocarpine, 222, 424

Reiter's disease, 157

Pin hole test, 556

Retina/retinal

Pinguecula, 80

anatomy, 249

Placido's keratoscopic disc,

471

artery occlusion, 255

Polychromatic lustre, 182

breaks, 277

Polycoria, 137

coloboma, 252

Presbyopia, 41

degenerations, 269-272

Presumed ocular histoplasmosis

detachment, 275

syndrome, 158

dystrophies, 268

Prisms, 22

edema, traumatic, 406

Proptosis, 379-383

function tests, 184

Prostaglandin derivatives, 427

holes, 277

latanoprost, 427

tears, 277

Provocative tests, for

tumours of, 279

narrow angle glaucoma, 227

vein occlusion, 256

open angle glaucoma, 221

Retinitis, 253

Pseudo-papillitis, 30, 301

Retinitis pigmentosa, 268

Pseudophakia, 32

Retinoblastoma, 280

INDEX

603

Retinopathy

Sphincter pupillae, 134

central serous, 272

Spring catarrh, 74

coat's, 266

Squamous blepharitis, 344

diabetic, 259

Squamous cell carcinoma

hypertensive, 257

of conjunctiva, 87

in toxaemia of pregnancy, 259

of lids, 361

prematurity, 264

Staphylomas, 131, 470

sickle cell, 264

anterior, 122

Retinoschisis, 270

ciliary, 132

Retinoscopy, 547

equatorial, 132

Retrobulbar neuritis, 294

inter calary,131

Rhabdomyosarcoma, 394

posterior, 132, 470

Rhodopsin, 14

Stevens-Johnson syndrome, 353,365

Roenne's nasal step, 220

Stenopaeic slit test, 556

Rosacea keratitis, 108

Sterilization, 584

Rubeosis iridis, 144, 234, 257

Stickler syndrome, 270

Strabismus or squint, 320-336

alternating, 325

concomitant, 321

Saccadic systems, 317

convergent, 325

Sarcoidosis

divergent, 326

conjunctivitis, 79

incomitant, 330

uveitis, 156

latent, 321

Schematic eye, 26

paralytic, 330

Schirmer's test, 366

pseudo, 321

Schwalbe's line, 206

Sturge-Weber syndrome, 285

Sclera

Sturm's conoid,25, 36

anatomy, 127

Stye, 345

blue, 131

Subconjunctival haemorrhage, 83, 407

examination, 470

Superior limbic keratoconjunctivitis,

Scleritis, 129

111

Scotoma,

Swimming pool conjunctivitis, 68

arcuate, 219

Swinging flashlight test, 474

Bjerrum's, 219

Symblepharon, 353

ring, 219, 268

Sympathetic ophthalmitis, 160, 413

sickle-shaped, 219

Sympathomimetic drugs, 424

Scotometry, 482

Synchisis scintillans, 245

Seclusio pupillae, 144

Synechiae

Seidel's test, 200

anterior peripheral, 145

Senile macular degeneration, 274

posterior, 144

Serpiginous ulcer, 109

Synoptophore, 329

Shadow test, 548

Systemic diseases, ocular

SICS, 185, 186, 189

manifestations of, 433-441

Siderosis bulbi, 409

Sinus-cavernous thrombosis, 387

Sjogren's syndrome, 366

Skiascopy, 547

Tarsorrhaphy, 355

Slit-lamp, 544

Tattooing, corneal opacity, 122

Snow blindness, 111

Tay-Sach's disease, 478

Soemmerring's ring, 201

Tear film, 364

spasm of accomodation, 43

Test types

Spectacles, 43

Jaeger's, 466

Spherical aberrations, 27

Snellen's, 464

604

Comprehensive OPHTHALMOLOGY

Therapeutics, ocular

Uveitis 138-161

administration of, 417

aetiology, 138

antibacterial agents, 418

anterior, 141

antifungal agents, 422

hypertensive, 145, 233

antiglaucoma drugs, 423-427

leprotic, 115

antiviral drugs, 420

pathology of, 140

corticosteroids, 428

posterior, 148

non-steroidal anti-inflammatory

purulent, 150

drugs, 428

sarcoid, 156

viscoelastic substances, 429

syphilitic, 155

timolol, 424

toxoplasmosis, 157

Tobacco amblyopia, 296

treatment, 146

Tonometer/tonometry, 479-481

tuberculous, 155

applanation, 480

viral, 159

indentation, 479

schiotz, 479

Total internal reflection, 22

Toxemia of pregnancy,

Vernal conjunctivitis, 74

retinopathy, 259

Viral conjunctivitis, 68

Toxic amblyopia, 296

keratitis, 101

Toxocara, 158

uveitis, 159

Toxoplasmosis, 157

Viscoelastic substances, 429

Trabecular meshwork, 206

Vision

Trabeculectomy, 238

binocular, 318

Trabeculotomy, 213

colour, 17, 305

Trachoma, 62

distant, 464

Transillumination, 547

field of, 481

Traumatic cataract, 405

near, 465

Trichiasis, 348

physiology of, 14

Tuberculosis of

Vision 2020, 446, 451

uveal tract, 155

Visual acuity, 16, 464

Tuberous sclerosis, 285

Visual agnosia, 307

Tumours of

Visual field

conjunctiva, 86

confrontation test, 482

lacrimal gland, 376

defects in glaucoma, 216

lids, 359

examination of, 481

orbit, 392

Visual hallucination, 307

retina, 279

Visual illusions, 308

uveal tract,162

Visual pathway

Tylosis, 66

anatomy of, 287

lesions of, 290

Visually evoked response, 490

Vitrectomy

Ulcer, corneal, 92

open sky, 247

Ulcus serpens, 96

pars plana, 247

Ultrasonography, 491

Vitreous

Uveal tract,

anatomy, 243

anatomy of, 133

detachment, 244

blood supply, 135

haemorrhage, 246

coloboma, 137

liquefaction, 244

congenital anomalies, 137

opacities, 245

degeneration, 161

substitute of, 247

inflammations of, 138

surgery of, 246