Nicholas R. Galloway, MBCHB, BA, FRCS, MD,

Peter H. Galloway, MBBS, FRCOphth

FRCOphth

Consultant Ophthalmologist, St James’

Surgeon Emeritus

University Hospital, Leeds, UK

Eye, Ear, Nose and Throat Centre

University Hospital

Queen’s Medical Centre

Nottingham, UK

Winfried M.K. Amoaku, MBCHB, FRCS,

Andrew C. Browning, BSc, FRCOphth

FRCOphth, PhD

Division of Ophthalmology and Visual

Senior Lecturer and Honorary Consultant

Sciences, Eye, Ear, Nose and Throat Centre,

Ophthalmologist, University of Nottingham

University Hospital, Queen’s Medical

and University Hospital, Queen’s Medical

Centre, Nottingham, UK

Artwork marked with

symbol throughout the book is original to the 2nd edition (Galloway

NR, Amoaku WMK. Common Eye Diseases and their Management, 2nd edition. Springer-Verlag

London Ltd, 1999) and is being republished in this 3rd edition.

A catalogue record for this book is available from the British Library

Library of Congress Control Number: 2005925513

ISBN-10:

1-85233-985-3 3rd edition

e-ISBN 1-84628-033-8

Printed on acid-free paper

ISBN-13:

978-1-85233-985-2

ISBN

1-85233-050-3 2nd edition

ISBN

3-540-13659-2 1st edition

First published 1985

Second edition 1999

Third edition 2006

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Preface to Third Edition

It is a pleasure to welcome two new authors who have contributed to the third edition

of “Common Eye Diseases”: Peter Galloway and Andrew Browning. Six years have passed

since the last edition but even in this relatively short time there have been significant

advances in the diagnosis and management of eye disease and an update has become

necessary. Each author has taken a block of chapters for revision and, where needed,

illustrations have been added or removed. Apart from the four main authors, I am

indebted to Mr Roland Ling for his invaluable work on the chapter on the retina and

once again to Professor Rubinstein for his help with the chapter on contact lenses.

The original aims of the book have not been changed. It remains as a textbook for

medical students and those starting a career in ophthalmology, but also for those in

primary care who are likely to deal with eye problems, including nurses, optometrists

and general practitioners.

It has been the intention to keep explanations as simple and nontechnical as possible

without losing scientific accuracy; more detailed accounts should be sought in the larger

textbooks. An updated reference list for further reading is given at the end of the book.

An internet version of this edition is being planned and, in order to keep down the retail

price, some financial help is needed. For this we are grateful for the interest of Pfizer Ltd,

whose policy of educational support has allowed this edition to go forward at its present

low price.

Acknowledgements

Although it is now many years since the first edition appeared, I still owe a great debt to

my former secretary, Mrs A. Padgett, for her original help in preparing the basis for these

further editions. No amount of word processing can replace this painstaking work. In

this new edition, I have kept Geoffrey Lyth’s original cartoons, which will perhaps lighten

the heaviness of the text for those with an artistic bent. The two new authors have revised

a number of chapters and their fresh input to an ageing textbook has been essential and

much appreciated.

Finally, I would like to acknowledge the help and encouragement from Melissa Morton

of Springer-Verlag, who has kept the ball bouncing back into my court with great

efficiency and thereby played an important part in ensuring the birth of this new edition.

Preface to Second Edition

Like the first edition, this textbook is intended primarily for medical students, but it is

also aimed at all those involved in the primary care of eye disease, including general

practitioners, nurses and optometrists. The need for the primary care practitioner to be

well informed about common eye conditions is even more important today than when

the first edition was produced. A recent survey from North London has shown that 30%

of a sample of the population aged 65 and over are visually impaired in both eyes and a

large proportion of those with treatable eye conditions were not in touch with eye serv-

ices. It is clear that better strategies for managing problems of eyesight need to be set

up. One obvious strategy is the improved education of those conducting primary care

and it is hoped that this book will contribute to this. For this second edition, I am grate-

ful for the help of my coauthor Winfried Amoaku, whose personal experience in teach-

ing medical students here in Nottingham has been invaluable. His expertise in the

management of macular disease, now a major cause of sensory deprivation in the elderly,

is also evident in these chapters.

The format of the book has not changed but some of the chapters have been expanded.

For example, there is now a section dealing with the eye complications of acquired

immune deficiency syndrome (AIDS). This problem barely existed at the time of the first

edition. Cataract surgery has changed a great deal in this short time and is becoming

one of the commonest major surgical procedures to be performed in a hospital. The

management of glaucoma has also changed with the introduction of a range of new med-

ications. Our aim has been to keep the original problem-oriented layout and to keep it

as a book to read rather than a book to look at. There are a number of good atlases on

eye disease and some of these are mentioned in the section at the end on further reading.

Although the title of the book is “Common Eye Diseases”, some less common conditions

are mentioned and it is hoped that the reader will gain some overall impression of the

incidence of different eye diseases.

vii

The Scope of Ophthalmology

Although the eye and its surrounding structures

number of elderly people in the population. The

would seem to provide an ideal anatomical and

problem is that of sensory deprivation owing to

functional basis for specialisation, ophthalmol-

degenerative disease. Degenerative changes in

ogy can no longer regard itself as a specialty on

the eye are now a major cause of blindness and

its own but more the heading for a group of sub-

although support services are being developed

specialties. There are those who know all about

there is still no effective cure.

the pigment epithelium of the retina and yet

The broad and detailed scientific interest in

bow to those who have a special knowledge of

the eye and vision is witnessed by the large

the bipolar cells in the retina. Over the past 100

number of journals, conferences and meetings

years the science has advanced at an unbeliev-

that now exist, possibly more than in any other

able rate and with the increase in our knowledge

specialty. There are several hundred ophthal-

has come the development of treatments and

mological journals all contributing to the

cures, which have had a great impact on our

scientific literature on the subject and many are

everyday lives.

now accessible through the internet or on CD-

The importance of the eye and its function is

ROM. As an organ of clinical specialisation,

sometimes underrated, but a consideration of

the eye does have a special advantage; it can

the part played by vision in our consciousness

be seen. Using the slit-lamp microscope it is

makes us soon realise its value. If we think of

possible to examine living nerves, including

dreams, memories, photographs and almost

nervous system tissues and blood vessels, in a

anything in our daily existence, it is difficult to

manner that is not possible in other parts of the

express them without visual references. After a

body without endoscopy or biopsy. So much

little careful consideration of the meaning of

are the component parts of the eye on display

blindness, it is easy to sense the rational and

to the clinician that when a patient presents

irrational fears that our patients present to us in

to a casualty department with symptoms, the

the clinic. Nevertheless, in a modern European

explanation of the symptoms should be made

community the effects of blindness are not so

evident by careful examination. Compare this

apparent as in former years, and blind people

with the vague aches and pains that present

tapping their way about the street or begging

to the gastroenterologist or the neurologist,

for food are less in evidence to remind us of the

symptoms that might ultimately resolve with-

deprivation that they suffer. This is due to the

out any cause being found for them. The

effective application of preventive medicine and

student or newly qualified doctor must be

the efficacy of modern surgical techniques.

warned that if the patient presents with eye

However, in the western world we have a new

symptoms and no abnormality can be found

and increasing problem related to the increasing

after examination, then he or she must look

Common Eye Diseases and their Management

again, because it is likely that something has

in the eye associated with systemic diseases

been missed.

such as hypertension and anaemia became

Most of the work of the ophthalmologist is

recognised. Several blinding conditions limited

necessarily centred on the globe of the eye it-

to the eye itself, such as glaucoma and macula

self, and there are a number of conditions that

degeneration, were also described at this time.

are limited to this region without there being

But we must not belittle the developments

any apparent involvement of the rest of the

that had occurred before the invention of the

body. Ophthalmology is usually classified as

ophthalmoscope. In the eighteenth century, con-

a surgical specialty but it provides a bridge

siderable advances had been made in the tech-

between surgery and medicine. Most of the

nique and instrumentation of cataract surgery,

surgery is performed under the microscope and

and the science of optics was being developed

here the application of engineering principles in

to enable the better correction of refractive

the design of finer and finer instruments has

errors in the eye. If we go back to the seven-

played an important part. There is overlap with

teenth century, the existing ophthalmological

the fields of the plastic surgeons and the neuro-

services were definitely limited, as is revealed in

surgeons. On the medical side, the ophthal-

the writings of the famous diarist, Samuel

mologist has links with the physicians and

Pepys. Although we have no record of his eye

particularly the diabetic specialists and

condition other than his own, he did consult an

cardiologists, not to mention paediatricians

oculist at the time and unfortunately received

and dermatologists.

little comfort or effective treatment. His failing

eyesight brought his diary to an abrupt end in

spite of the use of “special glasses” and the

Historical Background

medicaments, which caused him great pain.

Although records of eye surgical techniques

In 1847, the English mathematician and inven-

go back as far as 3000 years, modern eye surgery

tor Charles Babbage showed a distinguished

was largely developed thanks to the introduc-

ophthalmologist his device for examining the

tion of cocaine and then of general anaesthesia

inside of the eye, but unfortunately this was

at the end of the nineteenth century. The use of

never exploited and it was not until 1851 that

eserine eye drops to reduce the intraocular pres-

Hermann von Helmholtz published his classic

sure in glaucoma was introduced at the same

description of his instrument, the ophthalmo-

time, this being the forerunner of a number of

scope. He developed the idea from his knowl-

different medical treatments that are now avail-

edge of optics and the fact that he had

able. Cataract surgery saw great advances at

previously demonstrated the “red reflex” to

the beginning of the twentieth century, with

medical students with a not dissimilar instru-

the introduction of the intracapsular cataract

ment. In principle, he had, for the purposes of

extraction. In the

1920s, successful attempts

his demonstration, looked through a hole in a

were being made to replace the detached retina,

small mirror, which reflected light from a lamp

which had previously been an irreversible cause

into the subject’s eye. This produced the red

of blindness. Such early surgical techniques

reflex in the pupil well known to photographers

have now been developed to produce some of

and night drivers and no doubt this fascinated

the most dramatic means of restoring sight. As

medical students at that time. Von Helmholtz

a spin-off from the last war came a revolution-

worked out that a similar device could be used

ary idea of “spare-part” surgery in the eye. The

to inspect the inside of the eye. According to

observation that crashed fighter pilots were able

correspondence of the time, it took him about a

to tolerate small pieces of perspex in their eyes

week to learn the technique of examining in

led to the use of acrylic intraocular implants, the

detail the structures within the eye and he wrote

lens of the eye being replaced by an artificial

a letter to his father telling him that he had made

one. Such spare-part surgery has now become

a discovery that was “of the utmost importance

commonplace, as will be seen in Chapter 11. The

to ophthalmology”. Soon after this, a mass of

operating microscope was introduced in the

descriptive information on the optic fundus

1960s, and with it came the development of fine

appeared in the scientific literature and modern

suture materials and the use of instruments too

clinical ophthalmology was born. The changes

small for manipulation with the naked eye. This

The Scope of Ophthalmology

in turn has led to small incision techniques and

optics is helpful and most important is a

sutureless surgery, which has made the day-case

considerable degree of manual dexterity. Good

cataract operation a routine. Forty years ago,

binocular vision goes along with the manual

the vitreous was a surgical no-man’s land, but

dexterity demanded by microscopic surgery.

instruments have now been developed that can

That is to say, the future surgeon should see well

cut, aspirate and inject fluid simultaneously, all

out of each eye and should be able to use the

these procedures being carried out through

eyes together to give proper stereoscopic vision.

fine-bore needles. Membranes, blood or foreign

In many cases, an interest in the subject is

bodies can now be removed from the vitreous

aroused in medical school by a mentor or a good

as a routine. Much important eye disease is

teacher. By and large, those who see ophthal-

inherited and it is not surprising that very

mology as a soft option are not happy in their

important advances have occurred recently in

career. Those who, as most doctors do, set out to

the field of ophthalmic genetics. The gene con-

improve the lot of the patient, find the specialty

trolling the development of the eye has now

very rewarding because it is undoubtedly

been identified and perhaps the answer to the

extremely effective in this respect.

tragic problem of inherited degenerative retinal

In the UK, medically qualified graduates can

disease is on the horizon.

start their eye training with a senior house

In the early days of the development of the

officer (SHO) job and thence look for a special-

specialty, a number of specialised hospitals

ist registrar post in one of the training centres.

were built throughout the UK. The first of these

A question sometimes asked is what jobs as an

was Moorfields Eye Hospital, founded largely to

SHO, other than ophthalmology, are best suited

combat the epidemic of trachoma, which was

to an eventual career in ophthalmology.

prevalent in London at the time. Subsequently

Obvious ones are in plastic surgery, neurology

other eye hospitals appeared in the main cities

or neurosurgery but sometimes a seemingly

of this country, often the result of pressures of

unrelated one can prove to be good experience.

local needs such as the treatment of industrial

The membership part of the FRCOphth

accidents. In recent years, there has been a ten-

qualification is needed at this point and once on

dency for eye departments to become incorpo-

the training ladder there is an exit examination

rated within the larger district general hospitals,

before training is completed. The rules about

although individual eye hospitals remain and

training arrangements can vary from time to

are still being built.

time and advice on this can be provided by the

Royal College of Ophthalmologists. A handbook

for trainees is supplied by the college on appli-

cation. When the doctor is fully trained, he or

Making a Career

she can decide whether to start applying for

in Ophthalmology

consultant posts or whether to gain a fellowship

in a subspecialty and perhaps obtain a higher

Ophthalmology is a popular specialty and so the

degree. At the present time consultant posts are

aspiring eye surgeon can expect considerable

often advertised as requiring some special

competition. There are certain essential require-

expertise, such as paediatric ophthalmology or

ments. First, an initial interest in physics and

retina surgery.

Basic Anatomy and Physiology of the Eye

The three coats of the eye are as follows:

Introduction

(a) Outer fibrous layer:

The eye is the primary organ of vision. Each one

• cornea

of the two eyeballs is located in the orbit, where

• sclera

it takes up about one-fifth of the orbital volume

• lamina cribrosa.

(Figure 2.1). The remaining space is taken up

(b) Middle vascular layer (“uveal tract”):

by the extraocular muscles, fascia, fat, blood

• iris

vessels, nerves and the lacrimal gland.

• ciliary body - consisting of the pars

The eye is embryologically an extension of

plicata and pars plana

the central nervous system. It shares many

common anatomical and physiological proper-

• choroids.

ties with the brain. Both are protected by bony

walls, have firm fibrous coverings and a dual

• pigment epithelium of the retina

blood supply to the essential nervous layer in

• retinal photoreceptors

the retina. The eye and brain have internal cav-

• retinal neurons.

ities perfused by fluids of like composition and

The three compartments of the eye are as

under equivalent pressures. As the retina and

follows:

optic nerve are outgrowths from the brain, it is

not surprising that similar disease processes

(a) Anterior chamber - the space between

affect the eye and central nervous system. The

the cornea and the iris diaphragm.

physician should constantly remind himself or

(b) Posterior chamber - the triangular space

herself of the many disease conditions that can

between the iris anteriorly, the lens and

simultaneously involve the eye and the central

zonule posteriorly, and the ciliary body.

nervous system.

the lens and zonule.

The three intraocular fluids are as follows:

Basic Structure of the Eye and

(a) Aqueous humour - a watery, optically

clear solution of water and electrolytes

Supporting Structures

similar to tissue fluids except that

aqueous humour has a low protein

The Globe

content normally.

The eye has three layers or coats, three com-

(b) Vitreous humour - a transparent gel

partments and contains three fluids (Figure 2.2).

consisting of a three-dimensional

Common Eye Diseases and their Management

Mucocutaneous junction

Cornea

Upper palpebral furrow

Iris

Ciliary body

Conjunctiva

Upper punctum

Sclera

Caruncle

Choroid

Retina

Lower punctum

Openings of tarsal glands

Figure 2.2. Layers of the globe.

Semilunar folds

Figure 2.1. Surface anatomy.

sixths are formed by the sclera and lamina

cribrosa. The cornea is transparent, whereas the

sclera, which is continuous within it, is white.

network of collagen fibres with the

The junction of cornea and sclera is known as

interspaces filled with polymerised

the limbus. The cornea has five layers antero-

hyaluronic acid molecules and water. It

posteriorly (Figure 2.3):

fills the space between the posterior

surface of the lens, ciliary body and

Epithelium and its basement membrane -

retina.

stratified squamous type of epithelium

with five to six cell layers of regular

(c)

Blood - in addition to its usual func-

arrangement.

tions, blood contributes to the main-

tenance of intraocular pressure. Most

Bowman’s layer - homogeneous sheet of

of the blood within the eye is in the

modified stroma.

choroid. The choroidal blood flow rep-

Stroma - consists of approximately 90%

resents the largest blood flow per unit

of total corneal thickness. Consists of

tissue in the body. The degree of

lamellae of collagen, cells and ground

desaturation of efferent choroidal

substance.

blood is relatively small and indicates

Descemet’s membrane

- the basement

that the choroidal vasculature has

membrane of the endothelium.

functions beyond retinal nutrition. It

Endothelium - a single layer of cells lining

might be that the choroid serves as a

the inner surface of Descemet’s membrane.

heat exchanger for the retina, which

absorbs energy as light strikes the

retinal pigment epithelium.

Epithelium

Clinically, the eye can be considered to be

Bowman’s membrane

composed of two segments:

1. Anterior segment - all structures from

(and including) the lens forward.

2. Posterior segment - all structures post-

Stroma

erior to the lens.

The Outer Layer of the Eye

Descemet’s membrane

Endothelium

The anterior one-sixth of the fibrous layer of the

eye is formed by the cornea. The posterior five-

Figure 2.3. The cornea.

Basic Anatomy and Physiology of the Eye

In the region of the limbus, the epithelium on

of the triangle

(mainly ciliary muscles) lies

the outer surface of the cornea becomes con-

against the sclera. The inner side is divided into

tinuous with that of the conjunctiva, a thin,

two zones: (1) the pars plicata forms the ant-

loose transparent nonkeratinising mucous

erior 2 mm and is covered by ciliary processes

membrane that covers the anterior part of the

and (2) the pars plana constitutes the posterior

sclera, from which it is separated by loose con-

4.5-mm flattened portion of the ciliary body.

nective tissue. Above and below, the conjunctiva

The pars plana is continuous with the choroid

is reflected onto the inner surface of the upper

and retina.

and lower lids. This mucous membrane, there-

The choroid consists of the following:

fore, lines the posterior surface of the eyelids

• Bruch’s membrane - membrane on the

and there is a mucocutaneous junction on the

external surface of the retinal pigment

lid margin. Although the conjunctiva is con-

epithelium (RPE). It consists of the base-

tinuous, it can be divided descriptively into three

ment membrane of RPE cells and chorio-

parts: palpebral (tarsal), bulbar and fornix.

capillaris. Between the two layers of

The sclera consists of irregular lamellae of

basement membrane are the elastic and

collagen fibres. Posteriorly, the external two-

collagenous layers. Small localised thick-

thirds of the sclera become continuous with the

enings of Bruch’s membrane

(which

dural sheath of the optic nerve, while the inner

increase with age) are called drusen.

one-third becomes the lamina cribrosa - the

• The choriocapillaris - a network of capil-

fenestrated layer of dense collagen fibres

laries supplying the RPE and outer retina.

through which the nerve fibres pass from the

retina to the optic nerve. The sclera is thickest

• Layer of larger choroidal blood vessels

posteriorly and thinnest beneath the insertions

external to the choriocapillaris.

of the recti muscles. There is a layer of loose

• Pigmented cells scattered in the choroid

connective tissue deep to the conjunctiva, over-

external to the choriocapillaris.

lying the sclera, called the episclera.

Inner Layer

Middle Layer

The inner layer of the eye, which lines the vas-

The middle layer is highly vascular. If one were

cular uvea, is the neurosensory layer. This layer

to peel the sclera away from this layer (not an

forms the retina posteriorly; but, anteriorly it

easy task), the remaining structure would

comes to line the inner surface of the ciliary

resemble a grape, as this middle layer, which is

body and iris as a two-layered pigment epithe-

called the uvea, is heavily pigmented as well as

lium. These same layers can be traced into the

being vascular. The anterior part of the uvea

retina, which is composed of an outer pigment

forms the bulk of the iris body and hence

epithelium and an inner sensory part, which

inflammation of the iris is called either anterior

contains the rods and cones, bipolar cells and

uveitis or iritis. The posterior part of the uvea is

ganglion cells (Figure 2.4). The junction of the

called the choroid.

retina and the pars plana forms a scalloped

The iris is the most anterior part of the uvea.

border known as the ora serrata.

It is a thin circular disc perforated centrally

It is important to note that the photoreceptor

by the pupil. Contraction of the iris sphincter

cells are on the external side of the sensory

muscle constricts the pupil, while contraction of

retina. The relationship of the retinal elements

the dilator pupillae muscle dilates the pupil.

can be understood most readily by following the

The ciliary body is part of the uveal tissue and

formation of the optic cup. As the single-cell

is attached anteriorly to the iris and the scleral

layer optic vesicle “invaginates” to form the two-

spur; posteriorly it is continuous with the

cell layered optic cup, the initially superficial

choroid and retina. The ciliary body is also

cells become the inner layer of the cup. The RPE

referred to as the intermediate uvea.

develops from the outer layer of the cup, facing

The ciliary body is triangular in cross-

the photoreceptors across the now obliterated

section. The anterior side of the ciliary body is

cavity of the optic vesicle. The neurons of the

the shortest and borders the anterior chamber

sensory retina differentiate from the inner layer

angle; it gives origin to the iris. The outer side

of the optic cup.

Common Eye Diseases and their Management

Ganglion cells

Bipolar cells

Lacrimal gland

Lacrimal artery

Long posterior ciliary artery

Rods and cones

Optic nerve

Pigment epithelium

Ophthalmic artery

Choroid

Internal carotid artery

Figure 2.4. The retina.

Figure 2.5. Blood supply of the eye.

Optic Nerve

The optic nerve meets the posterior part of the

Blood Supply

globe slightly nasal to the posterior pole and

slightly above the horizontal meridian. Inside

The blood supply of the globe is derived from

the eye this point is seen as the optic disc. There

three sources: the central retinal artery, the

are no light-sensitive cells on the optic disc -

anterior ciliary arteries and the posterior ciliary

and hence the blind spot that anyone can find in

arteries. All these are derived from the ophthal-

their field of vision. The optic nerve contains

mic artery, which is a branch of the internal

about one million nerve fibres, each of which

carotid. The central retinal artery runs in the

has a cell body in the ganglion cell layer of

optic nerve to reach the interior of the eye and

the retina

(Figure

2.6). Nerve fibres sweep

its branches spread out over the inner surface of

across the innermost part of the retina to reach

the retina supplying its inner half. The anterior

ciliary arteries emerge from the insertion of the

recti muscles and perforate the globe near the

Optic disc

Macula

iris root to join an arterial circle in the ciliary

body. The posterior ciliary arteries are the fine

branches of the ophthalmic artery, which pene-

trate the posterior pole of the eye. Some of these

supply the choroid and two or more larger

vessels run anteriorly to reach the arterial circle

in the ciliary body. The larger vessels are known

as the long posterior ciliary arteries, and those

supplying the choroid are known as the short

posterior ciliary arteries. The branches of the

central retinal artery are accompanied by an

equivalent vein, but the choroid, ciliary body

and iris are drained by approximately four

vortex veins. These leave the posterior four

quadrants of the globe and are familiar land-

marks for the retina surgeon (Figure 2.5).

Figure 2.6. The optic fundus.

Basic Anatomy and Physiology of the Eye

the optic disc. They can be seen with the

and pain is also sometimes experienced during

ophthalmoscope by carefully observing the way

laser coagulation treatment of the chorioretina

light is reflected off the inner surface of the

- this would seem to prove the existence of

retina (Figure 2.7). The retinal vessels are also

sensory fibres in the iris and choroid. The

embedded on the inner surface of the retina.

cornea is extremely sensitive, but again, the only

There is therefore a gap, which is the thickness

sensory endings are those for pain.

of the transparent retina, between the retinal

The visual pathways include the following:

vessels and the stippled pigment epithelium.

The retina:

Apart from the optic nerve, the posterior pole of

• rods and cones

the globe is also perforated by several long and

short ciliary nerves. These contain parasympa-

• bipolar cells

thetic, sympathetic and sensory fibres, which

• ganglion cells.

mainly supply muscles of the iris (dilator and

Axons of the ganglion cells visual and

sphincter) and ciliary body (ciliary muscles).

pupillary reflex pathways:

Patients can experience pain when the iris is

• nerve fibre layer of retina

handled

under

inadequate

local

anaesthesia,

• optic nerve

• optic chiasm

• optic tract.

Subcortical centres and relays:

• superior colliculus - reflex control of

eye movements

• pretectal nuclei - pupillary reflexes

• lateral geniculate body - cortical relay.

Cortical connections:

• optic radiations

• visual cortex

(area

17) - vision and

reflex eye movements

• association areas (areas 18 and 19)

• frontal eye field

- voluntary eye

movements.

the rods and cones are considered analo-

gous to the sensory organs for touch, pressure,

temperature, etc. then the bipolar cells may be

compared to the first-order sensory neurons

of the dorsal root ganglia. By the same token,

the retinal ganglion cells can be compared to

the second-order sensory neurons, whose cell

bodies lie within the spinal cord or medulla.

The Eyelids

The eyelids may be divided into anterior and

posterior parts by the mucocutaneous junction

- the grey line (Figure 2.8). The eyelashes arise

from hair follicles anterior to the grey line, while

the ducts of the meibomian glands (modified

Figure 2.7.

The normal fundus of a a Caucasian and b an

sebaceous glands) open behind the grey line.

African. The background is darker in the African owing to

increased pigment in the retinal pigment epithelium (RPE). The

The meibomian glands are long and slender,

nerve fibre layer is noticeable, especially along the superior and

and run parallel to each other, perpendicular to

inferior temporal arcades.

the eyelid margin, and are located in the tarsal

Common Eye Diseases and their Management

Levator muscle of Muller

nasolacrimal duct opens into the inferior

meatus of the nose.

The Extraocular Muscles

There are six extraocular muscles that help to

move the eyeball in different directions: the

superior, inferior, medial and lateral recti, and

the superior and inferior obliques. All these

muscles are supplied by the third cranial nerve

except the lateral rectus (supplied by the sixth

nerve) and superior oblique (fourth nerve).

All the extraocular muscles except the

Levator

inferior oblique originate from a fibrous ring

expansion

around the optic nerve (annulus of Zinn) at the

orbital apex. The muscles fan out towards the

eye to form a “muscle cone”. All the recti

Orbicularis

oculi

muscles attach to the eyeball anterior to the

equator while the oblique muscles attach behind

the equator. The optic nerve, the ophthalmic

blood vessels and the nerves to the extraocular

muscles (except fourth nerve) are contained

within the muscle cone (Figure 2.9).

Opening of

meibomian

The levator palpebrae superioris is associated

gland

with the superior rectus. It arises from just

above the annulus of Zinn, runs along the roof

Figure 2.8.

The eyelid.

of the orbit overlying the superior rectus and

attaches to the upper lid skin and anterior

surface of the tarsal plate of the upper lid.

Tenon’s capsule is a connective tissue covering

plate of the eyelids. The tarsal plate gives stiff-

that surrounds the eye and is continuous with

ness to the eyelids and helps maintain its

the fascial covering of the muscles.

contour. The upper and lower tarsal plates are

about 1 mm thick. The lower tarsus measures

about 5 mm in height, while the upper tarsus

measures about 10-12 mm.

The orbicularis oculi muscle lies between

the skin and the tarsus and serves to close the

Levator palpebrae superioris

eyelids. It is supplied by the facial nerve. The

skin and subcutaneous tissue of the lids are

Superior oblique

thin. The inner surface of the eyelids is lined by

the palpebral conjunctiva.

Superior rectus

Optic nerve

The Lacrimal Apparatus

Medial

Inferior rectus

rectus

The major lacrimal gland occupies the superior

temporal anterior portion of the orbit. It has

ducts that open into the palpebral conjunctiva

above the upper border of the upper tarsus.

Tears collect at the medial part of the palp-

ebral fissure and pass through the puncta and

the canaliculi into the lacrimal sac, which term-

inates in the nasolacrimal duct inferiorly. The

Figure 2.9. Anatomy of the orbit.

Basic Anatomy and Physiology of the Eye

Physiology of the Eye

The Cornea

The primary function of the cornea is refrac-

The primary function of the eye is to form a clear

tion. In order to perform this function, the

image of objects in our environment. These

cornea requires the following:

images are transmitted to the brain through the

optic nerve and the posterior visual pathways.

• transparency

The various tissues of the eye and its adnexa

• smooth and regular surface

are thus designed to facilitate this function.

• spherical curvature of proper refractive

power

• appropriate index of refraction.

The Eyelids

Corneal transparency is contributed to by

anatomical and physiological factors:

Functions include: (1) protection of the eye

from mechanical trauma, extremes of temp-

Anatomical:

erature and bright light, and (2) maintenance

• absence of keratinisation of epithelium

of the normal precorneal tear film, which is

• tight packing of epithelial cells

important for maintenance of corneal health

and clarity.

• mucous layer providing smooth lubri-

Normal eyelid closure requires an intact

cated surface

nerve supply to the orbicularis oculi muscles

• homogeneity of membranes - Bowman’s

(facial nerve). Eyelid opening is affected by the

and Descemet’s

levator palpebrae superioris supplied by the

• regular arrangement of corneal lamel-

IIIrd cranial nerve.

lae (parallel collagen fibres within each

lamella, with adjacent lamellae being

perpendicular). Regularity produces a

diffraction grating

The Tear Film

• paucity of corneal stromal cells, which

The tear film consists of three layers: the

are flattened within lamellae

mucoid, aqueous and oily layers.

• interspaces - absence of blood vessels.

The mucoid layer lies adjacent to the corneal

Physiological

epithelium. It improves the wetting properties of

• active dehydration of the cornea

the tears. It is produced by the goblet cells in the

through Na⁺/HCO3- metabolic pump

conjunctival epithelium.

located in the corneal endothelium.

The watery (aqueous) layer is produced by

This dehydration is supplemented by

the main lacrimal gland in the superotemporal

the physical barrier provided by the

part of the orbit and accessory lacrimal glands

corneal epithelium and endothelium.

found in the conjunctival stroma. This aqueous

layer contains electrolytes, proteins, lysozyme,

immunoglobulins, glucose and dissolved

The Aqueous Humour

oxygen (from the atmosphere).

The oily layer (superficial layer of the tear

The aqueous humour is an optically clear sol-

film) is produced by the meibomian glands

ution of electrolytes (in water) that fills the

(modified sebaceous glands) of the eyelid

space between the cornea and the lens. Normal

margins. This oily layer helps maintain the ver-

volume is 0.3 ml. Its function is to nourish the

tical column of tears between the upper and

lens and cornea.

lower lids and prevents excessive evaporation.

The aqueous is formed by active secretion and

The tears normally flow away through a

ultrafiltration from the ciliary processes in the

drainage system formed by the puncta (inferior

posterior chamber. The fluid enters the anterior

and superior), canaliculi

(inferior and sup-

chamber through the pupil,circulates in the anter-

erior), the common canaliculus (opening into

ior chamber and drains through the trabecular

the lacrimal sac) and the nasolacrimal duct

meshwork into the canal of Schlemm,the aqueous

(which drains into the nose).

veins and the conjunctival episceral veins.

Common Eye Diseases and their Management

The aqueous normally contains a low con-

2. Circular fibres - form the inner part and

centration of proteins, but a higher concentra-

run circumferentially. Contraction moves

tion of ascorbic acid compared with plasma.

the ciliary processing inwards towards the

Inflammation of the anterior uvea leads to

center of the pupil leading to relaxation of

leakage of proteins from the iris circulation into

the zonules.

the aqueous (= plasmoid aqueous).

Accommodation

The Vitreous Body

Accommodation is the process whereby relax-

ation of zonular fibres allows the lens to become

The vitreous consists of a three-dimensional

more globular, thereby increasing its refractive

network of collagen fibres with the interspaces

power. When the ciliary muscles relax, the

filled with polymerised hyaluronic acid mole-

zonular fibres become taut and flatten the lens,

cules, which are capable of holding large quan-

reducing its refractive power. This is associated

tities of water. The vitreous does not normally

with constriction of the pupil and increased

flow but is percolated slowly by small amounts

depth of focus.

of aqueous. There is liquefaction of the jelly with

Accommodation is a reflex initiated by visual

age, with bits breaking off to form floaters. This

blurring and/or awareness of proximity of

degeneration occurs at an earlier age in myopes.

the object of interest. The maximum amount

of accommodation (amplitude of accommo-

dation) is dependent on the rigidity of the lens

The Lens

and contractility of the ciliary muscle. As the

lens becomes more rigid with age (and contrac-

The lens, like the cornea, is transparent. It is

tions of the ciliary body reduce), accommo-

avascular and depends on the aqueous for nour-

dation decreases. Reading and other close

ishment. It has a thick elastic capsule, which

work become impossible without optical

prevents molecules (e.g., proteins) moving into

correction - presbyopia.

or out of it.

The lens continues to grow throughout life,new

lens fibres being produced from the outside and

The Retina

moving inwards towards the nucleus with age.

This is the “photographic film” of the eye that

The lens is comprised of 65% water and 35%

converts light into electrical energy (transduc-

protein. The water content of the lens decreases

tion) for transmission to the brain. It consists of

with age and the lens becomes less pliable.

two main parts:

The lens is suspended from the ciliary body

by the zonule, which arises from the ciliary body

1. The neuroretina - all layers of the retina

and inserts into the lens capsule near the equator.

that are derived from the inner layer of the

embryological optic cup.

2. The RPE - derived from the outer layer of

The Ciliary Body

the optic cup. It is comprised of a single

layer of cells, which are fixed to Bruch’s

The ciliary muscle (within the ciliary body) is a

membrane. Bruch’s membrane separates

mass of smooth muscle, which runs circumfer-

the outer retina from the choroid.

entially inside the globe and is attached to the

The retinal photoreceptors are located on the

scleral spur anteriorly. It consists of two main

outer aspect of the neuroretina, an arrangement

parts:

that arose from inversion of the optic cup and

1. Longitudinal (meridional) fibres - form

allows close proximity between the photosens-

the outer layers and arise from the scleral

itive portion of the receptor cells and the

spur and insert into the choroid. Contrac-

opaque RPE cells, which reduce light scattering.

tion of this part of the muscle exerts trac-

The RPE also plays an important role in

tion on the trabecular meshwork and also

regeneration/recycling of photopigments of the

the choroid and retina.

eye and during light-dark adaptation.

Basic Anatomy and Physiology of the Eye

In order for the light to reach the photo-

vision in poor (dim) light and for the wide field

receptors to form sharp images, all layers of the

of vision.

retina inner to the photoreceptors must be

The retinal capillary network (derived from

transparent. This transparency is contributed to

the central retinal artery) extends no deeper

by the absence of myelin fibres from the retinal

than the inner nuclear layer and nourishes the

neurons. The axons of the retina ganglion cells

neuroretina from inside up to part of the outer

normally become myelinated only as they pass

plexiform layer. It is an end-arterial system. The

through the optic disc to enter the optic nerve.

choroid serves to nourish the RPE and the

There are two main types of photoreceptors

photoreceptors

(by diffusion of nutrients).

in the retina - the rods and the cones. In the

There are no blood vessels in the outer retina.

fovea centralis the only photoreceptors are

The central fovea is completely avascular and

cones, which are responsible for acute vision

depends on diffusion from the choroidal circ-

(visual details) and colour vision. Outside the

ulation for its nourishment. Thus, normal func-

fovea, rods become more abundant towards the

tioning of the retina requires normal retinal and

retinal periphery. The rods are responsible for

choroidal circulation.

Examination of the Eye

As in all other medical examinations, examin-

the camera around to the relevant views and

ation of a patient with an eye problem should

allows the camera (or macula) to make sense of

include history, physical examination and

the scene. If the macula area is damaged by, for

special investigation. The age as well as social

example, age-related macular degeneration, the

history, including the occupation of the patient,

patient might be unable to see even the largest

should not be forgotten in such evaluation. A

print on the test type and yet have no difficulty

summary of such evaluation is provided in

in walking about the room. Navigational vision

Table 3.1.

is largely dependent on the peripheral field of

vision. On the other side of the coin, the patient

with marked constriction of the peripheral field

of vision but preservation of the central field

How to Find Out What a

might behave as though blind. The same patient

Patient Can See

could read the test chart down to the bottom

once he has found it. This situation sometimes

One obvious way to measure sight is to ask the

arises in patients with advanced chronic

patient to identify letters that are graded in size.

simple glaucoma.

This is the basis of the standard Snellen test for

It should be becoming clear that measuring

visual acuity (Figure 3.1). This test only meas-

the visual acuity, although very useful, is not an

ures the function of a small area of retina at the

adequate measure of vision on its own. For a

posterior pole of the eye called the macula. If we

proper clinical examination, we need to assess

stare fixedly at an object, for example a picture

the visual fields and colour vision. A number of

on the wall, and attempt to keep our eyes as still

other facets of visual function can also be meas-

as possible, it soon becomes apparent that we

ured, such as dark adaptation or the perception

can only appreciate detail in a small part of the

of flicker.

centre of the field of vision. Everything around

us is ill-defined and yet we can detect the slight-

est twitch of a finger from the corner of our eyes.

Visual Acuity

The macula region is specialised to detect fine

detail, whereas the whole peripheral retina is

The familiar Snellen chart has one large letter at

concerned with the detection of shape and

the top, which is designed to be just visible to a

movement. In order to see, we use the periph-

normal-sighted person at 60 m. The chart is

eral retina to help us scan the field of view. The

viewed from a distance of 6 m. If a patient is just

peripheral retina can be considered as equiv-

able to see this large letter, the vision is recorded

alent to the television cameraman who moves

as 6/60. Below the large letter are rows of smaller

Common Eye Diseases and their Management

Table 3.1.

History

Age

Ophthalmic:

Subnormal vision

Duration. Difference

between eyes

Disturbances of vision

Distortion, haloes,

floaters, flashing

lights, momentary

losses of vision -

field defects

Pain/discomfort

Increase/decrease

Discharge

Change in

appearance -

discolouration

Change in lacrimation

Swelling/mass

Diplopia

Displacement

General medical:

Diabetes/

hypertension/

COAD/dysthyroid/

connective tissue

disease

Drugs

FH social/

Figure 3.1. The Snellen chart.

occupational

Examination

letters, decreasing in size down to the bottom.

The size of letter normally visible to a normal-

VA: distance/near (with and

without glasses)

sighted person at 6 m is usually on the second-

Colour vision

to-bottom line. Patients reading this line are

Visual fields

said to have a vision of 6/6. If a patient cannot

Orbit

Proptosis/

read the top letter, he is taken nearer to the

enophthalmos

chart. If the top letter becomes visible at 3 m, the

Ocular movements -

Eyelids and lacrimal

acuity is recorded as 3/60. If the letter is still not

conjugate and convergence

apparatus

visible, the patient is asked if he can count

Pupils

Intraocular pressure

fingers (recorded as “CF”) and, failing this, if

Position of eyes

he can see hand movements (“HM”). Finally, if

Conjunctiva, cornea

even hand movements are not seen, the ability

Iris

to see a light is tested (“PL”).

Media - lens/vitreous

Fundus - retina/choroid,

optic disc

Special investigations

Fluorescein angiography

Radiological and ultrasound

Haematological/biochemical

Bacteriological/immunological

Diagnosis

Anatomical

E.g., cataract

Aetiological

E.g., diabetes

Figure 3.2. The Stycar test.

Examination of the Eye

Young children and illiterates can be asked to

do the “E” test, in which they must orient a large

wooden letter “E” so that it is the same way up

as an indicated letter “E” on a chart. Perhaps

better than this is the Stycar test (Figure 3.2), in

which the child is asked to point at the letter on

a card that is the same as the one held up at

6 m. Other ways of measuring visual acuity are

discussed in Chapter 17.

Visual Field

Figure 3.4. Ishihara plates for colour vision.

Some measurements of the visual field can be

made by sitting facing the patient and asking if

the movement of one’s fingers can be discerned.

The patient is instructed to cover one eye with

a hand and the observer also covers one of his

eyes so that he can check the patient’s field

records the reliability of the patient by showing

against his own. The test can be made more

false-positive and false-negative errors. In prac-

accurate by using a pin with a red head on it as

tice this is very useful, as poor reliability is often

a target. None of these confrontation methods

an explanation for poor performance.

can match the accuracy of formal perimetry. A

number of specialised instruments of varying

complexity are available. Using such equipment,

Colour Vision

the patient is presented with a number of

different-sized targets in different parts of the

The Ishihara plates provide a popular and effec-

visual field, and a map of the field of vision is

tive method for screening for colour vision

charted. An accurate map of the visual field is

defects (Figure 3.4). The patient is presented

often of great diagnostic importance. In the

with a series of plates on which are printed

past, it was customary to map out the central

numerous coloured dots. The normal-sighted

part of the visual field using the Bjerrum screen,

subject will see numbers on the majority of the

and the peripheral field using a perimeter. The

plates, whereas the colour-defective patient will

Goldmann perimeter was then introduced, and

fail to see many of the numbers. The test is easy

this instrument allows both central and periph-

to do and will effectively screen out the more

eral fields to be plotted out on one chart. The

common red-green deficiency found in 8% of

Humphrey field analyser is a further develop-

the male population. There are other tests avail-

ment in field testing. It provides an automated

able that will measure blue-green defects, for

visual field recording system (Figure 3.3). It also

example, the City University test. Other tests,

such as the Farnsworth 100 Hue test, are avail-

able for the more detailed analysis of colour

vision.

Spectacles

Measurement of the visual acuity might not be

valid unless the patient is wearing the correct

spectacles. Some patients, when asked to read a

Snellen chart, will put on their reading glasses.

As these glasses are designed for close work,

the chart might be largely obscured and the

uninitiated doctor might be surprised at

Figure 3.3. The Humphrey field analyser

the poor level of visual acuity (Figure 3.5). If the

Common Eye Diseases and their Management

How to Start Examining

an Eye

Evaluating the Pupil

Examination of the pupil is best performed in a

dimly lit room.

Size and symmetry of pupils is assessed by

asking the patient to fixate on a distant object,

such as a letter on the Snellen chart. A dim light

is then directed on to the face from below so that

both pupils can be seen simultaneously in the

diffuse illumination. Normally, the two pupils in

any individual are of equal size, although slight

I borrowed my husband‘s glasses

differences in size might be observed in up to

20% of the population. Usually, physiological

Figure 3.5. The uninitiated might be surprised at the poor level

unequal pupils (anisocoria) remain unaltered

of visual acuity.

by changing the background illumination.

In order to assess the pupil light reflex, a

strong focal light is shone on the pupils, one

after the other. The direct reaction and the

consensual reaction (other pupil) are observed.

If the afferent arc of the pupil pathway were

normal, the direct and consensual reactions

would be equal.

glasses have been left at home, long sight or

To assess the near response of the pupil, ask

short sight can be largely overcome by asking

the patient to gaze at a distant object (e.g.,

the patient to view the chart through a pinhole.

Snellen chart), then at a near object (e.g., his

Similarly, an appropriate spectacle correction

own finger tip just in front of his nose). Observe

(near) must be worn when testing visual fields

the pupil as the patient changes gaze from

and colour vision. In an ophthalmic depart-

distant to near fixation and vice versa. Gener-

ment, a check of the spectacle prescription is a

ally, if the pupil light reflex is intact, the near

routine part of the initial examination. Figure

reflex is normal.

3.6 shows how the converging power of the

optical media and the length of the eye are mis-

External Eye and Lids

matched to produce the need to wear spectacles

(the dotted lines indicate the paths for rays of

The eyelids should be inspected to make sure

light without any corrective lens).

that the lid margins and puncta are correctly

HYPERMETROPE

MYOPE

Figure 3.6. Optical defects of the eye.

Examination of the Eye

aligned against the globe and that there are no

ingrowing lashes. Early basal cell carcinomas

(also known as rodent ulcers) on eyelid skin can

easily be missed, especially if obscured by cos-

metics. The presence of ptosis should be noted

and the ocular movements assessed by asking

the patient to follow a finger upwards, down-

wards and to each side. Palpation of the skin

around the eyes can reveal an orbital tumour or

swollen lacrimal sac. Palpation with the end of

a glass rod is sometimes useful to find points of

tenderness when the lid is diffusely swollen.

Such tenderness can indicate a primary infec-

tion of a lash root or the lacrimal sac. Both sur-

faces of the eyelids should be examined. The

Figure 3.7. Focal illumination.

inside of the lower lid can easily be inspected by

pulling down the skin of the lid with the index

finger. The upper lid can be everted by asking

that can be used for this purpose. A magnified

the patient to look down, grasping the lashes

image of the anterior segment of the eye can be

gently between finger and thumb, and rolling

viewed with a direct ophthalmoscope held

the lid margins upwards and forwards over a

about 1/3 m away from the eye through a +10 or

cotton-wool bud or glass rod. The lid will

+12 lens. The principle has been developed to a

usually remain in this everted position until the

high degree in the slit-lamp (Figure 3.8). This

patient is asked to look up. Foreign bodies quite

instrument allows a focused slit of light to be

often lodge themselves under the upper lid and

shone through the eye, which can then be exam-

they can only be removed by this means. As a

ined by a binocular microscope. By this means,

general rule, if a patient complains that there is

an optical section of the eye can be created.

something in his eye, there usually is, and if you

The method can be compared with making

find nothing, it is necessary to look again more

a histological section, where the slice of

closely or refer the patient for microscopic

tissue is made with a knife rather than a beam

examination. A feeling of grittiness can result

from inflammation of the conjunctiva and this

might be accompanied by evidence of purulent

discharge in the lashes. The presence of tear

overflow and excoriation of the skin in the outer

canthus should also be noted.

The Globe

Much ophthalmic disease has been described

and classified using the microscope. In spite of

this, many of the important eye diseases can be

diagnosed using a hand magnifier and an

ophthalmoscope. At this point, it is important to

understand the principle of examining the eye

with a focused beam of light. If a pencil of light

is directed obliquely through the cornea and

anterior chamber, it can be made to illuminate

structures or abnormalities that are otherwise

invisible. One might inspect the glass sides and

water of a fish tank using a strong, focused torch

in the same manner (Figure 3.7). Many ophthal-

moscopes incorporate a focused beam of light

Figure 3.8. Slit-lamp examination.

Common Eye Diseases and their Management

of light. The slit-lamp is sometimes called the

biomicroscope. By means of such optical aids,

the cornea must be carefully inspected for scars

or foreign bodies. The presence of vascular con-

gestion around the corneal margin might be of

significance. Closer inspection of the iris might

show that it is atrophic or fixed by adhesions.

Turbidity or cells in the aqueous might be seen

in the beam of the inspection light. The lens and

Figure 3.10. The Tonopen.

anterior parts of the vitreous can be examined

by the same means.

Once the anterior segment of the eye has been

read from a dial. The readings provided by this

examined, the intraocular pressure is measured.

measurement are highly reproducible and are

The “gold-standard” method of measurement is

given in millimetres of mercury (mmHg).

to use the Goldmann tonometer (Figure 3.9),

Some optometrists, however, employ “air-

which relies on the principle of “applanation”.

puff ” tonometers, which are more portable and

In essence, the application of this principle

do not require attachment to a slit-lamp. These

provides a derived measurement of intraocular

instruments are excellent for screening but

pressure by flattening a small known area of

are generally not as accurate as applanation

cornea with a variable force. The amount of force

tonometers. A convenient hand-held instru-

required to flatten a specific area is proportional

ment (the Tonopen) is available (Figure 3.10)

to the intraocular pressure reading, and this is

and is commonly used by ophthalmologists

when a slit-lamp is not available.

At this stage, the pupil can be dilated for

better examination of the fundi and optical

media. A short-acting mydriatic is preferable,

for example tropicamide 1% (Mydriacyl). These

particular drops take effect after 10 min and take

2-4 h to wear off. Patients should be warned that

their vision will be blurred and that they will be

more sensitive to light over this period. Most

people find that their ability to drive a car is

unimpaired, but there is a potential medicolegal

risk if the patient subsequently has a car accid-

ent. Once the pupils have been dilated, the eye

can then be examined with the ophthalmoscope.

How to Use the

Ophthalmoscope

Before the middle of the nineteenth century,

nobody had seen the inside of a living eye and

much of the science of medical ophthalmology

was unknown. In 1851, Hermann von Helmholtz

introduced his ophthalmoscope and it rapidly

became used in clinics dealing with ophthalmo-

logical problems. The task of von Helmholtz was

to devise a way of looking through the black

pupil and, at the same time, illuminate the

Figure 3.9. The Goldmann tonometer

interior of the globe. He solved the problem by

Examination of the Eye

arranging to view the fundus of the eye through

ophthalmoscope adjusted so that fundus detail

an angled piece of glass. A light projected from

becomes visible. It is best to look for the optic

the side was reflected into the eye by total inter-

disc first, remembering its position nasal to the

nal reflection. Most modern ophthalmoscopes

posterior pole and slightly above the horizontal

employ an angled mirror with a small hole in it

meridian. The patient should be asked to look

to achieve the same end. They also incorporate

straight ahead at this point. The important

a series of lenses that can be interposed between

points to note about the disc are the clarity of

the eye of the patient and that of the observer,

the margins, the colour, the nature of the central

thereby overcoming any refractive problems

cup, the vessel entry and the presence or

that might defocus the view. These lenses are

absence of haemorrhages. Once the disc has

positioned by rotating a knurled wheel at the

been examined carefully, the vessels from the

side of the ophthalmoscope. A number on the

disc can be followed. For example, the upper

face of the instrument indicates the strength of

temporal branch vessels can be followed out to

the lens. When choosing an ophthalmoscope, it

the periphery and back, then the lower tempo-

is worth remembering that large ones take

ral branch vessels, then the upper nasal vessels

larger batteries, which last longer (or, better still,

and then, finally, the lower nasal vessels. Having

they might have rechargeable batteries); small

examined the vessels, ask the patient to look

ophthalmoscopes are handy for the pocket.

directly at the ophthalmoscope light and the

Some ophthalmoscopes have a wider field of

macular region should come into view. At first,

view than others and this is an advantage when

this might look unremarkable, like a minute dot

learning to use the instrument.

of light that follows our own light. More careful

If examining the patient’s right eye, it is best

examination will reveal that it has a yellowish

to hold the ophthalmoscope in the right hand

colour. To obtain a highly magnified view of

and view through one’s own right eye. A left eye

the macular region, it is usually necessary to

should be viewed with the left eye using the left

examine it with a special contact lens on the slit-

hand (Figure 3.11). It is best if the patient is

lamp microscope, the Goldmann fundus lens. A

seated and the doctor is standing. The first thing

fundus photograph is also helpful. After viewing

to observe is the red reflex, which simply refers

the macula, the general fundus background

to the general reddish colouring seen through

should be observed. The appearance here

the pupil. If viewed from about 30 cm away from

depends on the complexion of the patient: in a

the eye, slight and subtle opacities or defects in

lightly pigmented subject, it is possible to see

the optical media can be seen against the back-

through the stippled pigment epithelium and

ground of the red reflex. The patient’s eye must

obtain an indefinite view of the choroidal vas-

always be brought into focus by rotating the lens

culature. In heavily pigmented subjects, the

wheel on the ophthalmoscope.

pigment epithelium is uniformly black and

Having observed the red reflex, the eye can

prevents any view of the choroid, which lies

be approached closely and the focus of the

behind it. Finally, the peripheral fundus can be

inspected by asking the patient to look to the

extremes of gaze and by refocusing the ophthal-

moscope. Examining the peripheral fundus

demands some special skill, even with the

ordinary ophthalmoscope, but it is best seen

using the triple-mirror gonioscope. This is a

modified contact lens that has an angled mirror

attached to it. A view through this mirror is

obtained using the slit-lamp microscope.

There are a number of other methods of

examining the fundus. The ophthalmoscope

described above is known as the direct ophthal-

moscope. The indirect ophthalmoscope was

introduced shortly after direct ophthalmoscopy.

If one examines an eye with the pupil dilated

Figure 3.11. Direct ophthalmoscopy

through a mirror with a hole in it, the patient

Common Eye Diseases and their Management

Figure 3.14. Fluorescein angiogram of normal fundus.

Figure 3.12. Indirect ophthalmoscopy.

being at arm’s length from the observer and the

convex lenses provide inverted reversed images

mirror being held close to the observer’s eye, the

like the indirect ophthalmoscope. Another

red reflex is seen. If a convex lens is placed in

useful way of examining the fundus is by means

the line of sight about 8 cm from the patient’s

of fundus photography. The photographs

eye, then, rather surprisingly, a clear wide field

provide a permanent record of the fundus. A

inverted view of the fundus is obtained. The

special type of fundus photograph, known as a

view can be made binocular, and the binocular

fluorescein angiogram, shows up the retinal

indirect ophthalmoscope is an essential tool of

vessels, including the capillaries, in great detail.

the retinal surgeon (Figure 3.12). If we want

The technique involves taking repeated photo-

a highly magnified view of the fundus, the

graphs in rapid succession after the injection of

slit-lamp microscope can be used. However, a

the dye fluorescein into the antecubital vein. The

special lens must be placed in front of the

dye in the vessels is selectively photographed by

patient’s eye. This can be in the form of the

using filters in the camera (Figure 3.14). Indo-

triple-mirror contact lens

(Figure

3.13). In

cyanine green angiography (ICG) is more useful

recent years, it has become a routine practice to

in assessing the choroidal circulation as

examine the fundus with the slit-lamp and

ICG-A fluorescence is transmitted through the

strong convex lenses (e.g., VOLK +60, +78 or

retinal pigment epithelium

(RPE; compared

+90DS aspheric lenses). These high-power

with fluorescein [Figure 3.15]). Video filming is

Figure

3.15. Indocyanine green angiography of normal

Figure 3.13. The Goldmann triple mirror.

fundus.

Examination of the Eye

becoming an important method for observing

changing events in the fundus and it is now pos-

sible to view a real-time image of the optic

fundus on a television screen using the scanning

laser ophthalmoscope. This type of equipment

will undoubtedly become a routine tool for the

ophthalmologist.

Other Tests Available in

an Eye Department

Several special tests are available to measure the

Figure 3.17. The exophthalmometer.

ability of the eyes to work together. A depart-

ment known as the orthoptic department is

usually set aside within the eye clinic for making

the walls of the orbit caused by tumours.

these tests. When there is a defect of the ocular

Computed tomography

(CT) scanning has

movements, this can be monitored by means of

become an important diagnostic technique,

the Hess chart (see Chapter 14). The ability to

especially for lesions in the orbit (Figure 3.18),

use the eyes together is measured on the synop-

particularly those involving bony tissues. This

tophore, and any tendency of one eye to turn out

specialised X-ray has surpassed plain X-rays for

or in can be measured with the Maddox rod and

most ophthalmic purposes. Magnetic resonance

Maddox wing test (Figure 3.16). The use of

imaging (MRI) is more useful in assessing soft

contact lenses and also of intraocular implants

tissues of the orbit and cranium. Ultrasonogra-

has demanded more accurate measurements of

phy is a technique for measuring the length of

the cornea and of the length of the eye. A ker-

the eye (which is a prerequisite for all cataract

atometer is an instrument for measuring the

surgery); it can also be used to depict tissue

curvature of the cornea, and the length of the

planes within the eye, showing, for example, the

eye can now be accurately measured by ultra-

size of intraocular tumours or the presence of

sound. If one eye appears to protrude forwards

vitreous membranes. It can be used to deter-

and one wishes to monitor the position of the

mine the presence or absence of retinal diseases,

globes relative to the orbital margin, an exoph-

especially in eyes with opaque media

(e.g.,

thalmometer is used (Figure 3.17). X-rays of the

cataract or vitreous haemorrhage). Electro-

eye and orbit are still used. An X-ray is essential

retinography provides a measure of the electri-

if an intraocular foreign body is suspected and

it is useful for detecting bony abnormalities in

Figure 3.18. Computed tomography (CT) scan of eyes and orbit

Figure 3.16. The Maddox wing.

(normal).

Common Eye Diseases and their Management

Figure 3.19. The Heidelberg retina tomograph.

cal changes that take place in the retina when

Technological advances have led to increas-

the eye is exposed to light. It can indicate retinal

ing dependence on imaging devices, such as

function in the same way that the electrocar-

digital fundus cameras for retinal screening

diogram indicates cardiac function. The visually

in patients with diabetes. In addition, recent

evoked potential is a measure of minute electri-

laser technologies, such as the Heidelberg

cal changes over the back of the scalp, which

retina tomograph, allow for a quick and easy

occur when the eyes are stimulated with a

way of scanning the optic nerve head in

flashing light. This test has been shown to be

three dimensions

(Figure

3.19) and the

useful in detecting previous damage to the optic

retinal nerve fibre layer. This is especially

nerve in patients with suspected multiple

helpful in evaluating changes in patients with

sclerosis.

glaucoma.

Long Sight, Short Sight

It is useful to distinguish between long-sighted

patient. The clinical importance of this is that

and short-sighted patients as you will see later

with a little practice the physician can tell the

in this chapter, but straight away we come across

difference at a glance as the patient enters

a problem with terminology. Think of the

the room. This often helps with the diagnosis

“short-sighted” old man who cannot see to read

because certain eye diseases are associated with

without glasses and, at the same time, the

myopia and others with hypermetropia.

“short-sighted” young lady who cannot see

The nature of the spectacle correction can be

clearly in the distance. The term “short sight” is

verified by moving the lens from side to side in

used in these instances unwittingly by the

front of one’s hand. If the hand appears to move

layman to mean two different situations; either

in the opposite direction to that of the move-

it can mean presbyopia (caused by diminished

ment of the spectacle lens, it is convex (Figure

focusing power with ageing, as in the case of the

4.3). The spectacles of the myopic patient

old man) or it can mean myopia (caused by a

contain concave, or diverging, lenses and, if

larger eyeball, as in the case of the young lady).

these are moved to and fro in front of one’s

Leaving aside presbyopia for the time being,

hand, the hand appears to move in the same

we need to realise that the myopic person has

direction as the movement. As a further clue,

physically larger than normal eyes, with an

when we look at the hypermetrope from a slight

anteroposterior diameter of more than 24 mm,

angle, the line of the cheek goes out behind the

and, by contrast, the hypermetropic (or long-

magnifying lenses and vice versa for the myope

sighted person) person has smaller than usual

(see Figures 4.1 and 4.2).

eyes, with an anteroposterior diameter of less

Here, again, let us remind ourselves that

than 24 mm. To obtain a clear image, this abnor-

hypermetropia and myopia have nothing to do

mal length of the eye needs optical correction

with presbyopia, which is the failure of the eyes

with a lens to bring light rays to a focus on the

to focus on near objects, appearing in middle

retina. The hypermetropic requires a convex

age. This is nothing to do with the length of the

lens to converge the rays, whereas the myopic

eyeball but is related to a diminished ability to

person requires a concave lens to make light

change the shape of the lens. It is corrected in

rays diverge before reaching the eye.

otherwise normal eyes by using a convex lens.

Glasses with convex lenses in them make the

Obviously myopes, hypermetropes and those

eyes look bigger and glasses with concave lenses

with no refractive error are all susceptible

in them make the eyes look smaller. Figure 4.1

to presbyopia.

shows a long-sighted (hypermetropic) patient

When we examine hypermetropic and

whose glasses seem to enlarge the eyes and

myopic eyes with the ophthalmoscope, we find

Figure

4.2 shows a short-sighted

(myopic)

that there are physical differences between the

Common Eye Diseases and their Management

Figure 4.3. Concave lens “with”; convex lens “against”. Try this

for yourself in the clinic.

two. The optic disc of the hypermetrope tends

to be smaller and pinker, and in extreme cases,

especially in children, the disc can appear to be

swollen when in fact it is quite normal. By con-

trast, the optic disc of the myope is larger and

paler with well-defined margins and can be mis-

taken for an atrophic disc.

Figure 4.1.

A long-sighted person.

Hypermetropia is associated with certain eye

conditions, notably narrow-angle glaucoma and

childhood amblyopia of disuse. Myopia is asso-

ciated with other conditions, particularly retinal

detachment, cataract and myopic retinal degen-

eration.You must be aware, though, that whereas

Table 4.1. Eye disease and refractive error.

Myopia (“short sight”)

Hypermetropia

(“long sight”)

Conditions associated

Conditions associated with

with myopia

hypermetropia

Retinal detachment

Narrow-angle glaucoma

Macula haemorrhages

Concomitant squint

Cataract

Amblyopia of disuse

Myopic chorioretinal

degeneration

Down’s syndrome

Keratoconus (conical

cornea)

Conditions causing

myopia

hypermetropia

Large eye

Small eye

Cataract

Retinal detachment

Diabetes mellitus

Orbital tumours

Accommodation spasm,

Macula oedema

or “pseudomyopia”

Congenital glaucoma

Figure 4.2.

A short-sighted person.

Long Sight, Short Sight

refractive errors are extremely common, these with seeing flashes of light, he may be about to

particular conditions are relatively rare in the have a retinal detachment.

general population. Table 4.1 shows a more com-

If we take note of whether a patient is long

prehensive list of these associations.

sighted or short sighted at an early stage, this

Having observed the nature of the spectacle information can influence the type of questions

lenses, we have now made a small step towards that are best asked when taking a history.

diagnosing the eye condition. If the patient

Finally, it is worth remembering that the

is middle aged and complaining of evening myopic patient can see objects close at hand and

headaches, seeing haloes around street lights read without glasses at any age, whereas the

and, at the same time, blurring of vision, hypermetropic patient has to focus to see at

narrow-angle glaucoma is the wrong diagnosis all distances. If the hypermetrope has good

if the patient is myopic. It could well be the right focusing power (i.e., the younger patient), the

diagnosis if the patient is hypermetropic. If the distance vision may be clear without glasses

patient in Figure 4.2 were to complain of the but when hypermetropia is more severe, the

sudden appearance of black spots combined

unaided vision is poor at all ranges.

Common Diseases of the Eyelids

lus and thence into the tear sac (Figure 5.1).

The Watering Eye

The tear sac is connected directly to the naso-

lacrimal duct, which opens into the inferior

Quite often, patients present at the clinic or

meatus of the nose below the inferior turbinate

surgery complaining of watering eyes. It could be

bone. The lacrimal puncta are easily visible to

the golfer whose glasses keep misting up on the

the naked eye and, in the elderly, the opening

fairway, the housewife who is embarrassed by

of the lower punctum can appear to project

tears dropping on food when cooking, or the

upwards like a miniature volcano. Inadequate

six-month-old baby whose eyes have watered

drainage of tears can result from displacement

and discharged since birth. Sometimes an

of the punctum; the lower lid in the elderly

elderly patient might complain of watering eyes

sometimes becomes turned inwards

(entro-

when on examination there is no evidence of tear

pion) because the whole tarsal plate rotates on

excess but the vision has been made blurred by

a horizontal axis (Figure 5.2). This, in turn, is

cataracts. Some degree of tear overflow is, of

caused by slackening of the fascial attachments

course, quite normal in windy weather, and the

of the lower margin of the tarsal plate. At first,

anxious patient can overemphasise this; it is

the eyelid turns in whenever the patient screws

important to assess the actual amount of

up the eyes but, eventually, the lid becomes

overflow by asking the patient whether it occurs

permanently turned in so that the lashes are no

all the time both in and out of doors.

longer visible externally and rub on the cornea.

An eye can water because the tears cannot

Such patients complain of watering, sore eyes

drain away adequately or because there is exces-

and the matter can be corrected effectively by

sive secretion of tears.

eyelid surgery. Entropion can also result from

scarring and contracture of the conjunctiva on

Impaired Drainage of Tears

the inner surface of the eyelid.

Not only can the punctum become turned

Normally, the tears drain through two minute

inwards, but it can also be turned outwards.

openings at the inner end of the lid margins,

Sometimes the eversion is slight, but enough to

known as the upper and lower lacrimal puncta.

cause problems. The patient might have been

using eyedrops, which, combined with the

The Lacrimal Passageway

overflow of tears, sometimes causes excoriation

Most of the tears drain through the lower

and contracture of the skin of the lower eyelid.

punctum. The puncta mark the opening of the

This leads to further eversion or ectropion

lacrimal canaliculi and these small tubes

of the lower eyelid

(Figure

5.3). Often, the

conduct tears medially to the common canalicu-

ectropion arises as the result of increasing

Common Eye Diseases and their Management

Upper punctum

Sac

Canaliculus

Nasolacrimal

duct

Figure 5.1. The lacrimal passageway.

laxity of the skin in the elderly but it might also

result from scarring and contracture of the skin

caused by trauma (cicatricial ectropion). Ectro-

pion can be corrected effectively by suitable

Figure 5.3. Ectropion.

lid surgery.

Drainage of tears along the lacrimal canali-

culi depends to some extent on the muscular

sac and it is thought that the walls of the sac

action of certain fibres of the orbicularis oculi

are thereby stretched, producing slight suction

muscle. This band of fibres encloses the lacrimal

along the canaliculi. Whatever the exact mech-

anism, when the orbicularis muscle is paralysed,

the tear flow is impaired even if the position of

the punctum is normal. Sometimes patients

who have suffered a Bell’s palsy complain of a

watering eye even though they appear to have

otherwise made a complete recovery.

Misplacement of the drainage channels, par-

ticularly of the punctum, can thus affect the

outflow of tears, but perhaps more commonly

the drainage channel itself becomes blocked. In

young infants with lacrimal obstruction, the

blockage is usually at the lower end of the naso-

lacrimal duct and takes the form of a plug of

mucus or a residual embryological septum that

has failed to become naturally perforated. In

these cases, there is nearly always some purulent

discharge, which can be expressed from the tear

sac by gentle pressure with the index finger over

the medial palpebral ligament. The mother is

shown how to express this material once or

twice daily and is instructed to instil antibiotic

drops three or four times daily. This treat-

ment alone can resolve the problem and many

cases undoubtedly resolve spontaneously.

Sometimes it is necessary to syringe and probe

the tear duct under a short anaesthetic. Usually

Figure 5.2.

Bilateral entropion. The inwardly turned lower

one waits until the child is at least nine months

eyelids are largely obscured by purulent discharge.

old before considering probing. In adults, the

Common Diseases of the Eyelids

Figure 5.4. Dacryocystogram (with acknowledgement to Mr R. Welham).

obstruction is more often in the common

stages, the condition can be aborted by the use

canaliculus or nasolacrimal duct. In these cases

of local and systemic antibiotics, but once an

the tear duct can be syringed after the instil-

abscess has formed this can point and burst on

lation of local anaesthetic drops. This procedure

the skin surface. Surgical incision and drainage

is simple, although it must be done with care to

of a lacrimal abscess can lead to the formation

avoid damaging the canaliculus, and even if the

of a lacrimal fistula (Figure 5.5).

obstruction is not cleared, it can allow the

Rarely, the lacrimal canaliculi can become

surgeon to identify the site of the obstruction.

infected by the fungus Actinomycosis and a

Sometimes a permanent obstruction is

small telltale bead of pus can be expressed

identified at the lower end of the nasolacrimal

from the punctum. The condition is resistant to

duct, which can be relieved by surgery under

ordinary treatment with local antibiotics, and is

general anaesthesia or the more recently intro-

best treated by opening up the punctum with a

duced laser treatment applied through the nose.

fine knife specially designed for the purpose -

The initial investigation of lacrimal obstruction

the procedure being called canaliculotomy -

entails syringing and if this does not give the

and then irrigating the canaliculi and tear duct

information required, it is possible to display

with a suitable antibiotic.

the tear duct by X-ray using a radio-opaque con-

trast medium. This is injected into the lower

canaliculus with a lacrimal syringe (Figure 5.4).

The technique is known as dacryocystography.

Acute Dacryocystitis

Sometimes the lacrimal sac can become infec-

ted. This can occur in children or adults but is

more common in adult females. The condition

might present initially as a watering eye and, in

its early stages, the diagnosis can be missed if the

tear sac is not gently palpated and found to be

tender. Subsequently, there is marked swelling

and tenderness at the inner canthus and event-

Figure

5.5. Acute dacryocystitis

(with acknowlegement to

ually the abscess can point and burst. In its early

Mr R. Welham).

Common Eye Diseases and their Management

quate simply because the patient complains of

dryness, or even if the symptoms appear to be

improved by artificial tears.

The normal tear film consists of three layers

and the integrity of this film is essential for

comfort and more importantly for good vision.

The anterior, or outermost, layer is formed by

the oily secretion of the meibomian glands and

the layer next to the cornea is mucinous to allow

proper wetting by the watery component of the

tears, which lies sandwiched between the two.

This three-layered film is constantly maintained

Figure 5.6. Diagnostic use of lacrimal syringing. (1) Obstruction

by the act of blinking.

in canaliculus shown by regurgitation of saline back through

punctum. (2) Common canaliculus obstruction shown by return

of saline through upper punctum. (3) Obstruction in naso-

Causes

lacrimal duct shown by filling of lacrimal sac.

• Systemic disease with lacrimal gland

involvement:

The diagnosis of lacrimal obstruction there-

- sarcoidosis

fore depends firstly on an examination of

- rheumatoid

arthritis

(Sjögren’s

the eyelids, secondly on syringing the tear

syndrome).

ducts, and then if necessary dacryocystography.

Figure

5.6 illustrates the diagnostic use of

• Trachoma (chlamydial conjunctivitis and

lacrimal syringing.

keratitis - see next chapter).

• Neuroparalytic keratitis.

Excessive Secretion of Tears

• Exposure keratitis.

• Old age.

A wide range of conditions affecting the eye

• Other rare causes.

can cause an excessive production of tears, from

acute glaucoma to a corneal abscess, but these

do not usually present as a watering eye because

Signs

the other symptoms, such as pain or visual loss,

Slit-lamp Examination

are more evident to the patient. Occasionally the

unwary doctor can be caught out by an irrita-

In a normal subject, the tear film is evident as a

tive lesion on the cornea, which mimics the

rim of fluid along the lid margin and a

more commonplace lacrimal obstruction. For

deficiency of this can be seen by direct exam-

example, a small corneal foreign body or an

ination. Prolonged deficiency of tears can be

ingrowing eyelash can present in this way. Not

associated with the presence of filaments

uncommonly, a loose lash may float into the

microscopic strands of mucus and epithelial

lower lacrimal canaliculus where it might

cells, which stain with Rose Bengal. Punctate

become lodged,causing chronic irritation at the

staining of the corneal epithelium is also seen

inner canthus. Its removal after weeks of dis-

after applying a drop of fluorescein. In some dry

comfort produces instant relief and gratitude.

eye syndromes, for example, ocular pemphigoid

and Stevens-Johnson syndrome, keratin-

isation of the cornea and conjunctiva with the

The Dry Eye

formation of contracting adhesions between the

opposed surfaces of the conjunctiva occurs. A

A patient might complain of dryness of the eyes

similar change is apparent following chemical

simply because the conjunctiva is inflamed, but

or thermal burns of the eyes.

when the tear film really is defective, the patient

might complain of soreness and irritation

Schirmer’s Test

rather than dryness. The diagnosis of a dry eye

depends on a careful examination and it is quite

One end of a special filter paper strip is placed

erroneous to assume that the tear film is inade-

between the globe and the lower eyelid. The

Common Diseases of the Eyelids

must not forget that there is also some smooth

muscle in the upper and lower eyelids, which

has clinical importance apart from its influence

on facial expression when the subject is under

stress. Loss of tone in this muscle accounts for

the slight ptosis seen in Horner’s syndrome;

increased tone is seen in thyrotoxic eye disease.

These muscles (that in the upper lid is known

as Muller’s muscle) are attached to the skeleton

of the lid, which is the tarsal plate, a plate of

fibrous tissue (not cartilage) that contains the

meibomian glands.

Figure 5.7. Schirmer’s test.

Epicanthus

Figure 5.9 shows that this is characterised by

vertical folds of skin at the inner canthus. These

other end projects forward and the time taken

folds are seen quite commonly in otherwise

for the tears to wet the projecting strip is meas-

normal infants and they gradually disappear as

ured. The test is not an accurate measure of

the facial bones develop. Children with epican-

tear secretion but it provides a useful guide

thus might

appear

the uninitiated to

(Figure 5.7).

Tear Film Break-up Time

Levator muscle of Muller

Using the slit-lamp microscope, the time for the

tear film to break up when the patient stops

blinking is measured. This test is sometimes

used as an index of mucin deficiency.

Management of the Dry Eye

This, of course, depends on the cause of the dry

eye and the underlying systemic cause might

require treatment in the first place. Artificial

tear drops are a mainstay in treatment and

various types are available, their use depending

on which component of the tear film is defec-

tive. In severe cases, it might be necessary to

consider temporary or permanent occlusion of

Levator

the lacrimal puncta.

expansion

Deformities of the Eyelids

Orbicularis

oculi

The Normal Eyelid

Figure 5.8 is a diagram of the normal eyelid in

cross-section. The lids contain two antagonistic

voluntary muscles: the more superficial orbicu-

Opening of

laris oculi, supplied by the seventh cranial

meibomian

nerve, which closes the eye, and the tendon of

gland

the levator palpebrae superioris, supplied by the

third cranial nerve, which opens the eye. We

Figure 5.8.

Cross-section of a normal eyelid.

Common Eye Diseases and their Management

upper eyelid caused by trachoma. This is rare in

the UK but still common in the Middle East and

countries where trachoma is still rife.

Ectropion

This commonly seen outward turning of the

lower eyelid in the elderly is eminently treatable

and responds well to minor surgery. Senile

ectropion can begin with slight separation of

the lower eyelid from the globe, and the mal-

position of the punctum leads to overflow of

tears and conjunctival infection. Irritation of the

skin by the tears and rubbing of the eyes lead to

Figure 5.9. Epicanthus.

skin contracture and further downward pulling

of the eyelids. Like entropion, ectropion can be

cicatricial and result from scarring of the skin

of the eyelids. It can also follow a seventh cranial

squinting and this can cause considerable

nerve palsy caused by complete inaction of

parental anxiety. It is important to explain that

the orbicularis muscle; this is called paralytic

the squint is simply an optical illusion once the

ectropion.

absence of any true deviation of the eyes has

been confirmed. Epicanthus persists into adult

life in Mongolian races, and occasionally it is

Lagophthalmos

seen in European adults. It can also be associ-

This is the term used to denote failure of proper

ated with other eyelid deformities.

closure of the eyelids caused by inadequate

blinking or lid deformity. In all these cases, the

Entropion

cornea is inadequately lubricated and exposure

keratitis can develop. If untreated, this can lead

This is an inversion of the eyelid. The common

to a serious situation; initially, the cornea shows

form is the inversion of the lower eyelid seen in

punctate staining when a drop of fluorescein is

elderly patients. Often, the patient does not

placed in the conjunctival sac and subsequently,

notice that the eyelid is turned in but complains

a corneal ulcer might appear. This, in turn, can

of soreness and irritation. Closer inspection

lead to the spread of infection into the eye and

reveals the inverted eyelid, which can be

without prompt treatment with antibiotics, the

restored to its normal position by slight down-

eye might eventually be lost.

ward pressure on the lower eyelid, only to turn

As a general principle, it is important to

in again when the patient forcibly closes the

realise that the sight could be lost simply

eyes. The inwardly turned eyelashes tend to rub

because the eyes cannot blink. The principle

on the cornea and, if neglected, the condition

applies especially to the unconscious or anaes-

can lead to corneal scarring and consequent loss

thetised patient, where a disaster can be avoided

of vision. The condition is often associated with

by taping or padding the eyelids and applying

muscular eyelids and sometimes seems to be

an antibiotic ointment.

precipitated by repeatedly screwing up the eyes.

Slackening of the fascial sling of the lower eyelid

with ageing combined with the action of the

Blepharospasm

orbicularis muscle allows this to happen. This

common type of entropion is called spastic

Slight involuntary twitching of the eyelids is

entropion and it can be promptly cured without

common and not usually considered to

leaving a visible scar by minor eyelid surgery.

be of any pathological significance other than

Entropion can also be seen following scarring of

being a symptom of fatigue or sometimes

the conjunctival surface of the eyelids and one

of an anxiety state. The condition is termed

must mention, in particular, the entropion of the

“myokymia”. True blepharospasm is rare. It can

Common Diseases of the Eyelids

be unilateral or bilateral and cause great in-

either upper or lower lids or both and is char-

convenience and worry to the patient. It tends

acterised by slight ptosis, small pupil, loss of

slowly to become more marked over many

sweating on the affected side of the face and

years. A small proportion of patients eventually

slight enophthalmos (posterior displacement of

develops Parkinsonism. Cases of recent onset

the globe).

need to be investigated because they might

The management of ptosis depends on the

result from an intracranial space-taking lesion.

cause and thus on accurate diagnosis. Surgical

In most cases, though, no underlying cause

shortening of the levator tendon is effective in

can be found. Patients with this type of ble-

some cases of congenital ptosis and sometimes

pharospasm

(essential blepharospasm) can

in long-standing third cranial nerve palsies.

often be treated quite effectively by injecting

Before embarking on surgery, it is important to

small doses of botulinum toxin into the eyelids,

exclude myasthenia gravis and corneal anaes-

but these need to be repeated every few months.

thesia. Children with congenital ptosis need

to be assessed carefully before considering

surgery. In young children, ptosis surgery is

Redundant Lid Skin

indicated where the drooping lid threatens to

Excessive skin on the eyelids is commonly seen

cover the line of sight and where the ptosis

in elderly people, often as a family characteris-

causes an unacceptable backwards tilt of the

tic. It might result from chronic oedema of the

head. In one rather strange type of congenital

eyelids caused, for example, by thyrotoxic eye

ptosis, the problem disappears when the mouth

disease or renal disease. The problem is made

is opened and the patient might literally wink

worse in some cases by herniation of orbital fat

unavoidably when chewing. Careful consider-

through the orbital septum, and excision of the

ation is needed before making the decision for

redundant skin and orbital fat might sometimes

surgery in these cases.

be necessary.

Causes of Ptosis

Ptosis

• Pseudoptosis: small eye, atrophic eye, lid

Drooping of one upper lid is an important clin-

retraction on other side.

ical sign. In ophthalmic practice, ptosis in chil-

• Mechanical ptosis: inflammation, tumour,

dren is usually congenital and in adults is either

and excess skin.

congenital or caused by a third cranial nerve

• Myogenic ptosis: myasthenia gravis.

palsy. These more common causes must always

• Neurogenic ptosis: sympathetic - Horner’s

be kept in mind but there are a large number of

syndrome, third cranial nerve palsy, any

other possible ones. When confronted with a

lesion in the pathway of these, carcinoma

patient whose upper lid appears to droop, the

of the lung can cause Horner’s syndrome.

first thing to decide is whether the eyelid really

• Drugs: guanethidine eye drops cause

is drooping or whether the lid on the other side

ptosis.

is retracted. The upper lid might droop because

the eye is small and hypermetropic or shrunken

• Congenital: ask for childhood photograph,

from disease. Having eliminated the possibility

ask for family history.

of such “pseudoptosis”, the various other causes

can be considered, beginning on the skin of the

Ingrowing Eyelashes (Trichiasis)

eyelid - styes, meibomian cysts - and advan-

cing centrally through muscle

- myasthenia

The lashes could grow in an aberrant manner

gravis

- along nerves

- oculomotor palsy,

even though the eyelids themselves are in good

Horner’s syndrome - to the brainstem. Marked

position. This might be the result of chronic

ptosis with the eye turned down and out and a

infection of the lid margins or follow trauma.

dilated pupil is an oculomotor palsy, whereas

Sometimes one or two aberrant lashes appear

slight ptosis, often not noticed by the patient or

for no apparent reason (Figure 5.10). The lashes

sometimes by the doctor, is more likely to mean

tend to rub on the cornea producing irritation

Horner’s syndrome. This syndrome is caused by

and secondary infection. The condition is

damage to the sympathetic nervous supply to

referred to as “trichiasis”. When one or two

Common Eye Diseases and their Management

becomes distended and cystic. The retained

secretions of the gland set up a granulating

reaction and the cyst itself might become

infected. The patient might complain of sore-

ness and swelling of the eyelid, which subsides,

leaving a pea-sized swelling that remains for

many months and sometimes swells up again.

During the stage of acute infection, the best

treatment is local heat, preferably in the form of

steam. This produces considerable relief and is

preferable to the use of systemic or local anti-

biotics. Antibiotics might be required if the

patient has several recurrences or if there are

signs and symptoms of septicaemia. Once a pea-

sized cyst remains in the tarsal plate, this can be

promptly removed under a local anaesthetic

unless the patient is a child, in which case

a general anaesthetic might be required. The

Figure 5.10. Trichiasis. This ingrowing eyelash on the lower

method of removal involves everting the eyelid

eyelid has been causing a sore eye for three months.

and incising the cyst through the conjunctiva

and then curetting the contents. Postoperatively,

local antibiotic drops or ointment are pre-

lashes are found to be the cause of the patient’s

scribed (Figure 5.11).

discomfort, it is common practice simply to

epilate them with epilating forceps. This prod-

uces instant relief, but often the relief is short-

Styes

lived because the lashes regrow. At this stage, the

best treatment is to destroy the lash roots by

These are distinct from meibomian infections,

electrolysis before epilation. Needless to say,

being the result of infection of the lash root.The

before removing lashes it is essential to be

eyelid might swell up and become painful and

familiar with the normal position of the lash

at this stage, the site of the infection can be

line and to realise, for example, that hairs are

uncertain. However, a small yellow pointing area

normally present on the caruncle. When the

is eventually seen around the base of an eyelash.

lash line is grossly distorted by injury or disease,

the rubbing of the lashes on the cornea can be

prevented by fitting a protective contact lens or,

if this measure proves impractical, it might be

necessary to transpose or excise the lashes and

their roots.

Infections of the Eyelids

Meibomian Gland Infection

The opening of the meibomian glands could

become infected at any age, resulting in mei-

bomitis, seen initially as redness along the line

of a gland when the eyelid is everted. A small

abscess might then form, with swelling and

redness of the whole eyelid, and this can point

and burst either through the conjunctiva or less

often through the skin. The orifice of a gland

could become occluded and the gland then

Figure 5.11. A meibomian cyst.

Common Diseases of the Eyelids

Hot steaming, again, is effective treatment and

to the lid margins twice daily with good effect

once the pus is seen, the eyelash can be gently

in many, but not all, cases. In severe cases with

epilated, with resulting discharge and sub-

ulceration of the lid margin, it might be neces-

sequent resolution of the infection.

sary to consider prescribing a systemic anti-

Children aged from about six to ten years

biotic, preferably after identifying the causative

sometimes seem to go through periods of their

organism by taking a swab from the eyelids.

lives when they can be dogged by recurrent styes

Local steroids when combined with a local

and meibomian infections, much to the distress

antibiotic are very effective treatment, but the

of the parents. Under these conditions, frequent

prescriber must be aware of the dangers of

baths and hairwashing are advised and some-

using steroids on the eye and long-term treat-

times a long-term systemic antibiotic might be

ment with steroids should be avoided. Steroids

considered. Recurrent lid infections can raise the

should not be used without monitoring the

suspicion of diabetes mellitus but in practice,

intraocular pressure.

this is rarely found to be an underlying cause.

Eyelid infections such as these rarely cause

any serious problems other than a day or two off

Molluscum Contagiosum

work and it is extremely unusual for the infec-

This is a viral infection usually seen in children.

tion to spread and cause orbital cellulitis. Recur-

The lesions on the eyelids are discrete, slightly

rent swelling of the eyelid in spite of treatment

raised and umbilicated and usually multiple.

can indicate the need for a lid biopsy because

There are also likely to be lesions elsewhere on

some malignant tumours can, on rare occasions,

the body, especially the hands, and brothers or

present in a deceptive manner.

sisters might have the same problem. It is rare

for the eye itself to be involved. In persistent

Blepharitis

cases, an effective form of treatment with chil-

dren is careful curettage of each lesion under a

This refers to a chronic inflammation of the lid

general anaesthetic; in adults, cryotherapy is

margins caused by staphylococcal infection. The

used for individual lesions, especially if they are

eyes become red rimmed and there is usually an

adjacent to the lid margin with the propensity

accumulation of scales giving the appearance of

to cause conjunctivitis.

fine dandruff on the lid margins. The condition

is often associated with seborrhoea of the scalp.

Sometimes it becomes complicated by recurrent

Orbital Cellulitis

styes or chronic infection of the meibomian

glands. The eye itself is not usually involved,

Although this is not strictly a lid infection, it

although there could be a mild superficial punc-

may be confused with severe meibomitis. The

tate keratitis, as evidenced by fine staining of the

infection is deeper and the implications much

lower part of the cornea with fluorescein. In

more serious. In a child, where the condition is

more sensitive patients, the unsightly appear-

more common, there is eyelid swelling, pyrexia

ance can cause difficulties, but in more severe

and malaise; urgent referral is needed. This

cases, the discomfort and irritation can interfere

applies especially if there is diplopia or visual

with work. Severe recurrent infection can lead

loss, because a scan will be required to decide

to irregular growth of the lashes and trichiasis.

whether surgical intervention is going to be

In the management of these patients, it is

needed to drain an infected sinus.

important to explain the chronic nature of the

condition and the fact that certain individuals

seem to be prone to it. Attention should be

Lid Tumours

given to keeping the hair, face and hands as

clean as possible and to avoid rubbing the eyes.

Benign Tumours

When the scales are copious, they can be gently

removed with cotton-wool moistened in

Papilloma

sodium bicarbonate lotion twice daily.Dandruff

of the scalp should also be treated with a suit-

Commonly seen on lids near or on the margin,

able shampoo. A local antibiotic can be applied

these can be sessile or pedunculated, and are

Common Eye Diseases and their Management

Haemangioma

Seen as a red “strawberry mark” at or shortly

after birth, this lesion can regress completely

during the first few years of life. Figure 5.13

shows a gross example of the rare cavernous

haemangioma, which might be disfiguring.

This also can regress in a remarkable way. “Port

wine stain” is the name applied to the capillary

haemangioma. This is usually unilateral and

when the eyelids are involved, there is a risk of

association with congenital glaucoma, haeman-

gioma of the choroid and haemangioma of the

Figure 5.12. Lid margin papilloma.

meninges on the ipsilateral side (Sturge-Weber

syndrome). Children with port wine stains

involving the eyelids need full ophthalmological

sometimes keratinised. These lesions are caused

and neurological examinations.

by the papilloma virus and are easily excised,

but care must be taken if excision involves the

Dermoid Cyst

lid margin (Figure 5.12).

These quite common lumps are seen in or

adjacent to the eyebrow. They feel cystic and

Naevus

are sometimes attached to bone. Typically, they

This is a flat brown spot on the skin; it might

present in children as a minor cosmetic

have hairs, and rarely becomes malignant.

problem. The cysts are lined by keratinised

Figure 5.13. a Large disfiguring haemangioma in infancy. b The same lesion, which in this case had remained untreated, showing

spontaneous regression.

Common Diseases of the Eyelids

epithelium and can contain dermal appendages

Malignant Melanoma

and cholesterol. A scan might be needed

This raised black-pigmented lesion is highly

before removal because some extend deeply into

malignant, but rare.

the skull.

Xanthelasma

Allergic Disease of the Eyelids

These are seen as yellowish plaques in the skin;

they usually begin at the medial end of the lids.

This can present as one of two forms or a

They are rarely associated with diabetes, hyper-

mixture of both. The more dramatic is acute

cholesterolaemia and histiocytosis. Usually,

allergic blepharitis in which the eyelids swell up

there is no associated systemic disease.

rapidly, often in response to contact with a plant

or eyedrops. The cause must be found and elim-

inated and treatment with local steroids might

Malignant Tumours

be needed. Chronic allergic blepharitis is seen in

atopic individuals, for example hay fever suffer-

Basal Cell Carcinoma

ers or patients with a history of eczema. The

This is the most common malignant tumour of

diagnosis might require a histological examin-

the lids, usually occurring on the lower lid. It

ation of the conjunctival discharge. Drop treat-

appears as a small lump, which tends to bleed,

ment to alleviate symptoms includes mast cell

forming a central crust with a slightly raised

stabilisers (such as lodoxamide) and histamine

hard surround. The tumour is locally invasive

antagonists

(such as emedastine), and these

only but should be excised to avoid spread into

agents could take weeks to take effect. Patients

bone. Even large lesions can be approached surg-

with seasonal allergic conjunctivitis might

ically (Figure 5.14) and “Mohs” micrographic

require medication for a prolonged period over

surgery is recognised as a tissue-sparing gold-

the spring and summer months each year.

standard approach in many centres. Radio-

therapy is only occasionally used with a greater

risk of recurrence than formal surgical excision.

Lid Injuries

Squamous Cell Carcinoma

One of the commonest injuries to the eyelids is

caused by the presence of a foreign body under

This tends to resemble basal cell carcinoma

the eyelid - a subtarsal foreign body. A small

and biopsy is needed to differentiate. It can also

particle of grit lodges near the lower margin of

be mimicked by a benign self-healing lesion

the lid, but to see it the lid must be everted.

known as keratoacanthoma.

Every medical student should be familiar with

the simple technique of lid eversion. This is per-

formed by gently grasping the lashes of the

upper lid between finger and thumb and at the

same time placing a glass rod horizontally

across the lid. The eyelid is then gently everted

by drawing the lid margin upwards and for-

wards. The manoeuvre is only achieved if the

patient is asked to look down beforehand, and

the everted lid is replaced by asking the patient

to look upwards. If a small foreign body is seen,

it is usually a simple matter to remove it using

a cotton-wool bud (Figure 5.15).

Cuts on the eyelids can be caused by broken

glass or sharp objects, such as the ends of screw-

drivers. The important thing here is to realise

Figure 5.14. Cystic basal cell carcinoma that has extended to

that cuts on the lid margin can leave the patient

involve most of the upper eyelid.

with a permanently watering eye if not sewn up

Common Diseases of the Conjunctiva and Cornea

and-socket joint. The analogy takes on more

Subconjunctival

meaning when the relation between conjunc-

Haemorrhage

tivitis and some joint diseases is seen.

There are a large number of different specific

This is common and tends to occur spontaneo-

causes of conjunctivitis. Some of these are inter-

usly or sometimes after straining, especially

esting but rare and it is important that the student

vomiting. It can also occur in acute haemor-

obtains an idea of the relative importance and

rhagic conjunctivitis caused by certain viruses

frequency of the different aetiological factors.

and occasionally bacterial conjunctivitis.The eye

For this reason, in this chapter a more or less

becomes suddenly red and although the patient

categorical list is given of the different causes. In

might experience a slight pricking, the condition

the chapter on the red eye (Chapter 7), you will

is usually first noticed in the mirror or by a

find a plan of approach to the red eye that deals

friend. The haemorrhage gradually absorbs in

with the importance and more common causes

about 14 days and investigations usually fail

of conjunctivitis seen in day-to-day practice.

to reveal any underlying cause. Rarely, it is

Although the conjunctiva is continuously

necessary to cauterise the site of bleeding if the

exposed to infection, it has special protection

haemorrhage is repeated so often that it becomes

from the tears, which contain immunoglobulins

a nuisance to the patient (Figure 6.1).

and lysozyme. The tears also help to wash away

debris and foreign bodies and this protective

action can explain the self-limiting nature of

Conjunctivitis

most types of conjunctivitis.

Inflammation of the conjunctiva is extremely

Symptoms

common in the general population and the

general practitioner is often expected to find out

In all types of conjunctivitis, the eye becomes

the cause and treat this condition. If we consider

red and feels irritable and gritty, as if there were

that the conjunctiva is a mucous membrane,

a foreign body under the lid. There is usually

which is exposed during the waking hours to

some discharge and if marked this may make

wind and weather more or less continuously,

the eyelids stick together in the mornings.

year in, year out, then it is not surprising that

Itchiness could also be present, especially in

this membrane is rather susceptible to

cases of allergic conjunctivitis. The discharge

inflammation. Furthermore, the conjunctiva

around the eyelids tends to make vision only

can be compared with the lining of a joint, the

intermittently blurred (if at all) and the patient

eye being considered as an unusual type of ball-

may volunteer that blinking clears the sight.

Common Eye Diseases and their Management

conjunctival scrapings have been taken. A drop

of local anaesthetic is placed in the conjunctival

sac and the surface of the conjunctiva at the site

of maximal inflammation is gently scraped with

the blade of a sharp knife or a Kimura spatula.

The material obtained is placed on a slide and

stained with Gram’s stain and Giemsa stain. The

infecting organism can thus be revealed or

the cell type in the exudate might indicate the

underlying cause.

Conjunctival Culture

Figure 6.1. Subconjunctival haemorrhage.

In most cases of conjunctivitis, it might be good

medical practice to take a culture from the con-

junctival sac and the eyelid margin, but such a

Signs

measure might not always be possible if a

microbiological service is not near at hand. The

Visual acuity is usually normal in conjunctiv-

cultures can be taken with sterile cotton-tipped

itis. The conjunctiva appears hyperaemic and

applicators and sent to the laboratory, in an

there can be evidence of purulent discharge on

appropriate medium, as soon as possible.

the lid margins, causing matting together of the

eyelashes. The redness of the conjunctiva

extends to the conjunctival fornices and is

Causes

usually less marked at the limbus. When a rim

• Bacterial.

of dilated vessels is seen around the cornea, the

examiner must suspect a more serious inflam-

• Chlamydial.

matory reaction within the eye.Apart from being

• Viral.

red to a greater or lesser degree,the eyes also tend

• Other infective agents.

to water, but a dry eye might lead one to suspect

• Allergic.

conjunctivitis results from inadequate tear

• Secondary to lacrimal obstruction,corneal

secretion. Drooping of one or both upper lids is

disease, lid deformities, degenerations,

a feature of some types of viral conjunctivitis

systemic disease.

and this can be accompanied by enlargement

• Unknown cause.

of the preauricular lymph nodes. The ophthal-

mologist should train himself or herself to feel

for the preauricular node as a routine part of the

Bacterial Conjunctivitis

examination of such a case. Closer inspection of

the conjunctiva might reveal numerous small

In the UK, the commonest organisms to cause

papillae, giving the surface a velvety look, or the

conjunctivitis are the pneumococcus, Haemo-

papillae may be quite large. Giant papillae under

philus spp. and Staphylococcus aureus. The last

the upper lids are a feature of spring catarrh, a

mentioned is normally associated with chronic

form of allergic conjunctivitis. Close inspection

lid infections, and the acute purulent conjunc-

of the conjunctiva might also reveal follicles or

tivitis, known more familiarly as “pink eye”, is

lymphoid hyperplasia. Being deep to the epith-

usually caused by the pneumococcus. Chronic

elium, they are small, pale, raised nodules and

conjunctivitis can also be caused by Moraxella

are commonly seen in viral conjunctivitis. Fol-

lacunata but this organism is rarely isolated

licles under the upper lids are especially charac-

from cases nowadays. An important but rare

teristic of trachoma.

form of purulent conjunctivitis is that caused by

Neisseria gonorrhoeae; this is still an occasional

cause of a severe type of conjunctivitis seen in

Microscopy

the newborn babies of infected mothers.

The examination of a severe case of conjunc-

Untreated, the cornea also becomes infected,

tivitis of unknown cause is not complete until

leading to perforation of the globe and perma-

Common Diseases of the Conjunctiva and Cornea

should be taken before starting treatment.

Commonsense precautions against spread of

the infection should also be advised, although

they are not always successful.

Attempts to culture bacteria from the conjunc-

tival sac of cases of chronic conjunctivitis do not

yield much more than commensal organisms.

One particular kind of chronic conjunctivitis

in which the inflammation is sited mainly near

to the inner and outer canthi is known as

angular conjunctivitis with follicles on the

superior tarsal conjunctiva. Another feature of

this is the excoriation of the skin at the outer

Figure 6.2. Ophthalmia neonatorum.

canthi from the overflow of infected tears. The

clinical picture has been recognised in associa-

tion with infection by the bacillus M. lacunata.

nent loss of vision. Purulent discharge, redness

Often, zinc sulphate drops and the application

and severe oedema of the eyelids are features of

of zinc cream to the skin at the outer canthus

the condition, which is generally known as oph-

are sufficient treatment in such cases. Tetracy-

thalmia neonatorum (Figure 6.2). Ophthalmia

cline ointment might be more effective.

neonatorum can also be caused by staphylococci

and the chlamydia (see inclusion conjunctivitis

of the newborn). The disease is notifiable and

Chlamydial Conjunctivitis

any infant with purulent discharge from the

eyes, particularly between the second and

The chlamydia comprise a group of “large

twelfth day postpartum, should be suspect. At

viruses” that are sensitive to tetracycline and

one time, special blind schools were filled with

erythromycin and that cause relatively minor

children who had suffered ophthalmia neonato-

disability to the eyes in northern Europe and the

rum. An active campaign against this cause of

USA when compared with the severe and wide-

blindness began at the end of the last century

spread eye infection seen especially in Africa

when Carl Crede introduced the principle of

and the Middle East. Inclusion conjunctivitis

careful cleansing of the infant’s eyes and the

(“inclusion blenorrhoea”) is the milder form of

instillation of silver nitrate drops. Blindness

chlamydial infection and is caused by serotype

from this cause has now disappeared in the UK

D to K of Chlamydia trachomatis. The condition

but there is still a low incidence of ophthalmia

is usually, but not always, sexually transmitted.

neonatorum. Those affected require treatment

The conjunctivitis typically occurs one week

with both topical medication (e.g., chloram-

after exposure. It can cause a more severe type

phenicol 0.5% eye drops) and intramuscular

of conjunctivitis in the newborn child, which

benzylpenicillin (a cephalosporin, such as cefo-

can also involve the cornea. The infection is

taxime, is an alternative). Both parents of the

usually self-limiting but often has a prolonged

child should also be assessed.

course, lasting several months. The diagnosis

Pink eye is the name given to the type of acute

depends on the results of conjunctival culture

purulent conjunctivitis that tends to spread

and examination of scrapings and the associa-

rapidly through families or around schools. The

tion of a follicular conjunctivitis with cervicitis

eyes begin to itch and within an hour or two

or urethritis.

produce a sticky discharge, which causes the

Chlamydial conjunctivitis responds to treat-

eyelids to stick together in the mornings. If the

ment with tetracycline. In children and adults,

disease is mild, it can be treated by cleaning

tetracycline ointment should be used at least

away the discharge with cotton-wool, and it

four times daily. In adults, the treatment can be

does not usually last longer than three to five

supplemented with systemic tetracycline, but

days. More severe cases might warrant the pre-

this drug should not be used systemically in

scription of antibiotic drops instilled hourly

pregnant mothers or children under seven years

during the day for three days followed by four

of age. Azithromycin and other macrolide anti-

times daily for five days. A conjunctival culture

biotics are known to be particularly effective

Common Eye Diseases and their Management

in treating systemic chlamydial infection;

azithromycin can be given conveniently as a

one-off dose. A referral to genitourinary med-

icine is advisable on presentation, as a screening

measure, because reinfection from partners can

trigger a recurrent infection.

Trachoma

Although a doctor practicing in the UK might

rarely see a case of trachoma, and even then

only in immigrants, it is the commonest cause

of blindness in the world and, furthermore, the

disease affects about 15% of the world’s pop-

ulation. It is spread by direct contact and per-

Figure 6.4. Adenoviral keratoconjunctivitis.

petuated by poverty and unhygienic conditions.

Trachoma is caused by C. trachomatis serotypes

A, B and C and affects underprivileged popula-

symptoms follow an upper respiratory tract

tions living in conditions of poor hygiene.

infection and, although nearly always bilateral,

The disease begins with conjunctivitis, which,

one eye might be infected before the other. The

instead of resolving, becomes persistent, esp-

affected eye becomes red and discharges;

ecially under the upper lid where scarring and

characteristically, the eyelids become thickened

distortion of the lid can result. The inflam-

and the upper lid can droop. The ophthalmolo-

matory reaction spreads to infiltrate the cornea

gist’s finger should feel for the tell-tale tender

from above and ultimately the cornea itself can

enlarged preauricular lymph node. In some

become scarred and opaque (Figure 6.3).At one

cases, the cornea becomes involved and subep-

time, trachoma was common in the UK, esp-

ithelial corneal opacities can appear and persist

ecially after the Napoleonic wars at the end of

for several months (Figure 6.4). If such opacities

the eighteenth century. It had been eliminated

are situated in the line of sight, the vision can be

by improved hygienic conditions long before the

impaired. There is no known effective treatment

introduction of antibiotics.

but it is usual to treat with an antibiotic drop to

prevent secondary infection.

Adenoviral Conjunctivitis

From time to time, epidemics of viral con-

junctivitis occur and it is well recognised that

Acute viral conjunctivitis is common. Several of

spread can result from the use of improperly

the adenoviruses can cause it. Usually, the eye

sterilised ophthalmic instruments or even con-

taminated solutions of eye drops, and poor

hand-washing techniques.

Herpes Simplex Conjunctivitis

This is usually a unilateral follicular conjunc-

tivitis with preauricular lymph node enlarge-

ment. In children, it might be the only evidence

of primary herpes simplex infection.

Acute Haemorrhagic Conjunctivitis

Acute haemorrhagic conjunctivitis is caused by

enterovirus

(picornavirus) and usually

Figure 6.3. Trachoma trichiasis of upper lid and corneal vasc-

occurs in epidemics. The disease is hugely con-

ularisation (with acknowledgement to Professor D. Archer).

tagious but self-limiting.

Common Diseases of the Conjunctiva and Cornea

Other Infective Agents

keratoconjunctivitis have a higher risk than

normal for the development of herpes simplex

The conjunctiva can be affected by a wide

keratitis; the condition is also associated with

variety of organisms, some of which are too rare

the corneal dystrophy known as keratoconus or

to be considered here, and sometimes the

conical cornea. They are likely to develop skin

infected conjunctiva is of secondary importance

infections and chronic eyelid infection by

to more severe disease elsewhere in the rest of

staphylococcus. The recurrent itch and irrit-

the body. Molluscum contagiosum is a virus

ation (in the absence of infection) is relieved by

infection, which causes small umbilicated

applying local steroid drops, but in view of the

nodules to appear on the skin of the lids and

long-term nature of the condition, these should

elsewhere on the body, especially the hands. It

be avoided if possible because of their side

can be accompanied by conjunctivitis when

effects. (Local steroids can cause glaucoma in

there are lesions on the lid margin. The infec-

predisposed individuals and aggravate herpes

tion is usually easily eliminated by curetting

simplex keratitis.)

each of the lesions. Infection from Phthirus

pubis (the pubic louse) involving the lashes and

Vernal Conjunctivitis (Spring Catarrh)

lid margins can initially present as conjunc-

Some children with an atopic history can

tivitis but observation of nits on the lashes

develop a specific type of conjunctivitis charac-

should give away the diagnosis.

terised by the presence of giant papillae under

the upper lid. The child tends to develop

Allergic Conjunctivitis

severely watering and itchy eyes in the early

spring, which can interfere with schooling.

Several types of allergic reaction are seen on the

Eversion of the upper lid reveals the raised

conjunctiva and some of these also involve the

papillae, which have been likened to cobble-

cornea. They may be listed as follows:

stones. In severe cases, the cobblestones can

coalesce to give rise to giant papillae (Figure

Hay Fever Conjunctivitis

6.5). Occasionally, the cornea is also involved,

initially by punctate keratitis but sometimes it

This is simply the commonly experienced red

can become vascularised. It is often necessary

and watering eye that accompanies the sneezing

to treat these cases with local steroids, for

bouts of the hay fever sufferer. The eyes are itchy

example, prednisolone drops applied if needed

and mildly injected and there might be con-

every two hours for a few days, thus enabling the

junctival oedema. If treatment is needed,

child to return to school. The dose can then be

vasoconstrictors, such as dilute adrenaline or

reduced as much as possible down to a main-

naphazoline drops, can be helpful; sodium

tenance dose over the worst part of the season.

cromoglycate eye drops can be used on a more

More severe cases can derive some benefit from

long-term basis. Systemic antihistamines are of

limited benefit in controlling the eye changes.

Atopic Conjunctivitis

Unfortunately, patients with asthma and eczema

can experience recurrent itching and irritation

of the conjunctiva. Although atopic conjunc-

tivitis tends to improve over a period of many

years, it might result in repeated discomfort and

anxiety for the patient, especially as the cornea

can become involved, showing a superficial

punctate keratitis or, in the worst cases, ulcer

formation and scarring.

The diagnosis is usually evident from the

history but conjunctival scrapings show the

Figure

6.5. Vernal conjunctivitis

(spring catarrh) papillary

presence of eosinophils. Patients with atopic

reaction.

Common Eye Diseases and their Management

topical cyclosporin drops, or eyelid injections of

climates as a natural ageing phenomenon, but

triamcinolone to control the inflammatory

under suitable conditions the heaped-up tissue

response. Less severe cases can respond well to

spreads into the cornea, drawing a triangular

sodium cromoglycate drops; these can be

band of conjunctiva with it. The eye becomes

useful as a long-term measure and in prevent-

irritable because of associated conjunctivitis

ing but not controlling acute exacerbations.

and in worst cases the degenerative plaque

Other medications with a similar modest

extends across the cornea and affects the vision.

benefit in symptoms include lodoxamide (a

The early stage of the condition, which is

mast cell stabiliser) and emedastine (a topical

common and limited to a small area of the con-

antihistamine).

junctiva, is termed a pingueculum and the more

advanced lesion spreading onto the cornea is

known as a pterygium (Figure 6.6). Pterygium

Secondary Conjunctivitis

is more common in Africa, India, Australia,

China and the Middle East than in Europe. It is

Inflammation of the conjunctiva can often

rarely seen in white races living in temperate cli-

be secondary to other more important pri-

mates. Treatment is by surgical excision if the

mary pathology. The following are some of the

cornea is significantly affected with progression

possible underlying causes of this type of

towards the visual axis; antibiotic drops might

conjunctivitis:

be required if the conjunctiva is infected. Non-

• Lacrimal obstruction

infective inflammation of pterygium is treated

• Corneal disease

with topical steroids.

• Lid deformities

Finally, when considering secondary causes

of conjunctivitis, one must be aware that

• Degenerations

redness and congestion of the conjunctiva with

• Systemic disease.

secondary infection can be an indicator of sys-

Lacrimal obstruction can cause recurrent

temic disease. Examples of this are the red eye

unilateral purulent conjunctivitis and it is

of renal failure and gout, and also polycythemia

important to consider this possibility in recal-

rubra. The association of conjunctivitis, arthri-

citrant cases because early resolution can be

tis and nonspecific urethritis makes up the triad

achieved simply by syringing the tear ducts.

of Reiter’s syndrome. Some diseases cause

Corneal ulceration from a variety of causes is

abnormality of the tears and these have already

often associated with conjunctivitis and here

been discussed with dry eye syndromes, the

the treatment is aimed primarily at the cornea.

most common being rheumatoid arthritis.

Occasionally, the presence of one of the two

However, there are other rarer diseases that

common acquired lid deformities, entropion

upset the quality or production of tears, such as

and ectropion, can be the underlying cause.

sarcoidosis, pemphigus and Stevens-Johnson

Sometimes the diagnosis may be missed, esp-

syndrome. Thyrotoxicosis is a more common

ecially in the case of entropion, when the defor-

mity is not present all the time. Other lid

deformities can also have the same effect. A

special type of degenerative change is seen in

the conjunctiva, which is more marked in hot,

dry, dusty climates. It appears that the com-

bination of lid movement in blinking, dryness

and dustiness of the atmosphere and perhaps

some abnormal factor in the patient’s tears or

tear production can lead to the heaping up of

subconjunctival yellow elastic tissue, which is

often infiltrated with lymphocytes. The lesion is

seen as a yellow plaque on the conjunctiva in the

exposed area of the bulbar conjunctiva and

usually on the nasal side. Such early degener-

ative changes are extremely common in all

Figure 6.6. Pterygium.

Common Diseases of the Conjunctiva and Cornea

dence of this occurrence on windy, dry days.

Small foreign bodies also become embedded as

the result of using high-speed grinding tools

without adequate protection of the eyes. The

dentist’s drill can also be a source of foreign

bodies, but the most troublesome are those

particles that have been heated by grinding or

chiselling. It is important to have some under-

standing of the anatomy of the cornea if one is

attempting to remove a corneal foreign body.

One must realise, for example, that the surface

epithelium can be stripped off from the under-

lying layer and can regrow and fill raw areas

with extreme rapidity. Under suitable cond-

itions the whole surface epithelium can reform

in about 48 h. The layer underlying, or posterior,

to the surface epithelium is known as Bowman’s

membrane and if this layer is damaged by the

injury or cut into unnecessarily by overzealous

use of surgical instruments, a permanent scar

might be left in the cornea. When the epithelium

alone is involved, there is usually no scar, and

healing results in perfect restoration of the

optical properties of the surface.

Figure 6.7. Acne rosacea.

The stroma of the cornea is surprisingly

tough, permitting some degree of boldness

systemic disease, which is associated with con-

when removing deeply embedded foreign

junctivitis, but the other eye signs, such as lid

bodies. It should be remembered that if the

retraction, conjunctival oedema and proptosis,

cornea has been perforated, the risk of intra-

are usually more evident. A rather persistent

ocular infection or loss of aqueous dictates that

type of conjunctivitis is seen in patients with

the wound should be repaired under full sterile

acne rosacea. Here, the diagnosis is usually, but

conditions in the operating theatre.

not always, made evident by the appearance of

the skin of the nose, cheeks and forehead, but

the corneal lesions of rosacea are also quite

Signs and Symptoms

characteristic (Figure 6.7). The cornea becomes

invaded from the periphery by wedge-shaped

Patients usually know when a foreign body has

tongues of blood vessels associated with recur-

gone into their eye and the history is clear-cut -

rent corneal ulceration. Severe rosacea kerato-

but not always. Occasionally, the complaint is

conjunctivitis is seen less commonly now,

simply a red sore eye, which might have been

perhaps because it responds well to treatment

present for some time. Spotting these corneal

with the combination of systemic doxycycline,

foreign bodies is really lesson number one in

lubricants for associated dry eye and the judi-

ocular examination. It involves employing the

cious use of weak topical steroids. Usually, it is

important basic principles of examining the

also necessary to instruct the patient to clean

anterior segment of the eye. Most foreign bodies

the lids and perform “lid hygiene”, as such

can be seen without the use of the slit-lamp

patients are often also affected by blepharitis.

microscope if the eye is examined carefully and

with a focused beam of light. Figure 6.8 dem-

Corneal Foreign Body

onstrates the great advantage of the focused

beam, and, in fact, this principle is used in slit-

Small particles of grit or dust commonly

lamp microscopy. If the foreign body has been

become embedded in the cornea and every

present for any length of time, there will be a

casualty officer is aware of the increasing inci-

ring of ciliary injection around the cornea

Common Eye Diseases and their Management

Figure 6.8. Focal illumination of corneal foreign body.

caused by the dilatation of the deeper episcleral

Once the foreign body has been removed, an

capillaries, which lie near the corneal margin.

antibiotic drop is placed in the eye and the lids

Ciliary injection is a sure warning sign of

are then splinted together by means of a firm

corneal or intraocular pathology.

pad. There is no doubt that the corneal epi-

thelium heals more quickly if the eyelids are

splinted in this way. It is usually advisable to see

Treatment

the patient the following day if possible to make

The aim of treatment is, of course, to remove the

sure that all is well, and if the damaged spot on

foreign body completely. Sometimes this is not

the cornea is no longer staining with fluor-

as easy as it might seem, especially when a hot

escein, the pad can be left off. Antibiotic drops

metal particle lies embedded in a “rust ring”. In

should be continued at least three times daily

instances when it is clear that much digging is

for a few days after the cornea has healed. The

going to be needed, it can be prudent to leave

visual acuity of the patient should always be

the rust ring for 24 h, after which it becomes

checked before final discharge.

easier to remove. The procedure for removing a

There are one or two factors that should

foreign body should be as follows: the patient

always be borne in mind when treating patients

lies down on a couch or dental chair and one or

with corneal foreign bodies: in most instances,

two drops of proparacaine hydrochloride 0.5%

healing takes place without any problem but,

(Ophthaine) or a similar local anaesthetic are

rarely, the vision can be permanently impaired

instilled onto the affected eye. A good light on a

by scarring. Also, on rare occasions, the site

stand is needed, preferably one with a focused

of corneal damage becomes infected and if

beam and the eyelids are held open with a

speculum (Figure 6.9). The doctor will also

usually require some optical aid in the form of

special magnifying spectacles, for example

“Bishop Harman’s glasses” or the slit-lamp.

Many foreign bodies can be easily removed with

a cotton-wool bud (particularly those lodged

under the upper lid), but otherwise at the slit-

lamp a 25-gauge orange needle angled nearly

perpendicular to the plane of the iris can be

used to lift off the foreign body. When the

foreign body is more deeply embedded, a

battery-powered handheld blunt-tipped drill

can be used to clean any rust deposits that

remain, again under the careful control of the

slit-lamp microscope.

Figure 6.9. Removing corneal foreign body.

Common Diseases of the Conjunctiva and Cornea

neglected, the infection can enter the eye and

Corneal Ulceration

cause endophthalmitis, with total blindness

of the affected eye. This is a well-recognised

Corneal ulcers can arise spontaneously

tragedy, which should never happen in an age of

(primary) or they might result from some defect

antibiotics. Of course, if the eye has been perfor-

in the normal protective mechanism or some-

ated, endophthalmitis is a frequent sequel in

times they are part of a more generalised sus-

the absence of antibiotic treatment. One only

ceptibility to infection (secondary). The nerve

has to examine old hospital case notes from the

endings in the cornea are pain-sensitive endings

pre-antibiotic era to obtain proof of this.

and a light touch is felt as a sharp pain. Fur-

It is important to remember that a perfor-

thermore, stimulation of these nerves causes a

ating injury of the eye is a surgical emergency.

vigorous blink reflex and the eye begins to water

Any doubt about the possibility of a perforating

excessively. An effective protective mechanism

injury of the cornea can usually be resolved by

is therefore brought into action, which tends to

examining it carefully with the slit-lamp micro-

clear away infection or foreign bodies and

scope. One other factor to bear in mind is the

warns the patient of trouble. In most instances

possibility of a retained intraocular foreign

of corneal ulceration, the eye is painful, photo-

body. Sometimes the patient can be quite

phobic and waters. The conjunctiva is usually

unaware of such an injury and this might

injected and there might be ciliary injection.

mislead the doctor into underestimating the

serious nature of the problem. The answer for

Types of Corneal Ulcer

the doctor is “when in doubt, X-ray”, especially

when a hammer and chisel or high-speed drill

Owing to Direct Trauma

have been used. A retained intraocular foreign

body might not set up an inflammatory reaction

The corneal epithelium becomes disrupted and

or irreversible degenerative changes until

abraded by certain characteristic injuries. It is

several weeks or even months have elapsed

surprising how the same old story keeps repeat-

(Figure 6.10).

ing itself: the mother caught in the eye by the

child’s fingernail, the edge of a newspaper, or the

backlash from the branch of a tree. The injury

is excruciatingly painful and the symptoms are

often made much worse by the rapid eye move-

ments of an anxious patient and sometimes by

vigorous rubbing of the eye. The patient com-

plains that there is something in the eye and

once the diagnosis has been made it can be

difficult to persuade the patient that there is no

foreign body. A denuded area of cornea is seen,

which stains with fluorescein. It might not be

possible to examine the patient until a drop of

local anaesthetic has been instilled into the eye,

but, as a general rule, local anaesthetic drops

should not be used to treat a “sore eye”. This

is because healing is impaired and serious

damage to the eye could result. Anaesthetic

drops should only be used as a single-dose

diagnostic measure in such cases. Treatment

involves the instillation of a mydriatic (such as

homatropine 1%) and an antibiotic ointment

(such as chloramphenicol 0.5%), after which

special care is needed to fix the eyelids. This is

probably best achieved by directly sticking the

Figure 6.10. Beware of the full-thickeness corneal scar, when in

eyelids together with two vertically placed short

doubt do an X-ray.

strips of micropore surgical tape. A pad is then

Common Eye Diseases and their Management

placed over the closed eyelids. The patient is

ately sore. Examination reveals conjunctival

then given some analgesic tablets to take home

congestion, which is often mainly localised to an

and is advised to rest quietly until the eye is

area adjacent to the corneal ulcer. The ulcer is

inspected the following day. The pad can be left

often seen as a white crescent-shaped patch near

off once the epithelium has healed over, but even

the corneal margin but there is usually, but not

then the patient should continue to instill an

always, a small gap of clear cornea between it

antibiotic ointment in the eye at night for

and the limbus (the corneoscleral junction).

several weeks. The reason for taking a little

Such marginal ulcers are thought to be caused

trouble over the management of a patient with

by exotoxins from S. aureus, mainly because

a corneal abrasion is the recurrent nature of the

they are often associated with S. aureus ble-

condition. All too often, after some months or

pharitis. On the other hand, it is not possible to

even a few years, the patient begins to experi-

grow the organism from the corneal lesion, and

ence a sharp pain in the injured eye on waking

for this reason, it is said that the infiltrated area

in the morning. It is as if the cornea, or the weak

is some form of allergic response to the infect-

part of the cornea, becomes stuck to the poste-

ing organism. Furthermore, these marginal

rior surface of the upper lid during the night.

ulcers respond rapidly to treatment with a

The pain wears off after an hour or two and

steroid-antibiotic mixture. It is essential that

when the patient presents to the doctor there

the usual precautions before applying local

might be no obvious cause for the symptoms. In

steroids to the eye are taken, that is to say, the

fact, careful examination with the slit-lamp

possibility of herpes simplex infection should

reveals minute cysts or white specks at the site

be excluded and the intraocular pressure should

of the original abrasion, indicating a weak area

be monitored if the treatment is to continue on

of attachment of the corneal epithelium. Severe

a more long-term basis.

recurrent corneal abrasion is best dealt with

A wide range of other bacteria are known to

in an eye department where slit-lamp control

cause corneal ulceration, but, by and large,

is available.

infections only occur as a secondary problem

when the defenses of the cornea are impaired

(e.g., by underlying corneal disease, trauma,

Owing to Bacteria

bullous keratopathy, dry eyes or contact

The commonest ulcer of this type is known as a

lens wear).

“marginal ulcer” (Figure 6.11). The patient com-

There are three bacteria that can produce

plains of a persistently red eye, which is moder-

corneal infection despite healthy epithelium:

N. gonorrhoea, Neisseria meningitidis and

diphtheria. Pathogens most often associated

with corneal infections, however, are S. aureus,

Streptococcus pneumoniae, Pseudomonas aerug-

inosa and the enterobacteria (Escherichia coli,

Proteus spp. and Klebsiella spp.). Pseudomonas

spp. is an especially virulent bacterium as it can

cause rapid corneal perforation if inadequately

treated.

Usually there is pain, photophobia, watering

and discharge in addition to redness. Examin-

ation reveals ciliary injection and a corneal

defect, which might have a greyish base (infiltra-

tion). There is most often an associated (sec-

ondary) iritis, which can be severe, giving rise

to a hypopyon (layer of pus in the anterior

chamber).

Bacterial corneal ulcers are sight threatening

and require urgent treatment. The causative

organism needs to be identified by corneal

Figure 6.11. Marginal ulcer caused by bacterial infection.

scrapes. Appropriate antibiotics, usually a

Common Diseases of the Conjunctiva and Cornea

combination of gentamicin and cefuroxime,

After a few days, or sometimes weeks, the

which are applied frequently in hospital,

epithelial lesion heals and at this point, complete

provide a broad spectrum until the organisms

resolution can occur or an inflammatory reac-

are identified.

tion can appear in the stroma deep to the

infected epithelium. The eye remains red and

Owing to Acanthamoeba spp.

irritable to an incapacitating degree and further

dendritic ulcers might subsequently appear. In

Acanthamoeba spp. are a free-living genus of

worse cases, the cornea can become anaesthetic

amoeba that has been increasingly associated

so that, although the eye might be more com-

with keratitis. The keratitis is usually chronic

fortable, the problems of a numb cornea are

and can follow minor trauma. Contact lens

added to the original condition. Healing tends

wearers are particularly at risk of this infection.

to occur with a vascular scar.

Owing to Viruses

Treatment of Herpes Simplex Keratitis

Apart from other rare types of virus infection,

there is one outstanding example of this

Antiviral agents are usually the first line of

herpes simplex keratitis. The condition seems to

treatment. Examples of currently used antiviral

be more common than it used to be, perhaps

agents are idoxuridine, trifluorothymidine,

because the incidence of other types of corneal

cytarabine and acyclovir. The most effective is

ulcer has become less with the more liberal

acyclovir. Unfortunately, none of these agents is

use of local antibiotics on the eye. Every eye

curative, but they are thought to have some

casualty department has a few patients with this

effect on acute rather than chronic cases. Early

debilitating condition, which can put a patient

diagnosis and treatment seem to give the best

off work for many months. Fortunately, it is only

chance of avoiding recurrences. The removal of

a few cases that cause such a problem, and most

virus-containing epithelial cells (debridement)

instances of this common condition give rise to

is now indicated only in cases that are resistant

a week or ten days of incapacity. Herpes simplex

to antiviral agents, where there is toxicity to the

is thought to produce a primary infection in

drugs, or there is difficulty in acquiring or

infants and younger children, which is trans-

applying the antiviral agents. An antibiotic drop

ferred from the lips of the mother and might be

and cycloplegic are instilled and a firm pad and

subclinical. Sometimes a vesicular rash develops

bandage applied. Touching the debrided area

around the eyelids, accompanied by fever and

with iodine is now obsolete. Following this pro-

enlargement of the preauricular lymph nodes.

cedure, the eye can become very sore and the

Whatever the initial manifestation of primary

patient is given an analgesic. Often the corneal

infection, it is thought that many members of

epithelium will heal after 48 h and the condition

the population harbour the virus in a latent

will be cured. Larger ulcers might not respond

form so that overt infection in an adult tends to

satisfactorily to this treatment. Steroids should

appear in association with other illnesses. Most

not be used in the treatment of dendritic ulcers

people are familiar with the cold sores that

of the cornea (Figure 6.12b). It is well recognised

appear on the lips because of herpes simplex.

that steroid drops enhance the replication of the

Sometimes, after a cold, one eye becomes sore

herpes simplex virus

(Figure

6.12c). They

and irritable and inspection of the cornea shows

reduce the local inflammatory reaction and

the characteristic corneal changes of herpes

could give the false impression that the eye is

simplex infection. A slightly raised granular,

improving. However, persistent use of local

star-shaped or dendriform lesion is seen, which

steroids in such cases could result in corneal

takes up fluorescein (Figure 6.12a). The virus

thinning and even corneal perforation. Once the

can be cultivated from this lesion and the size

dendritic ulcer has healed, residual stromal

of the dendriform figure is some guide to

infiltration is then sometimes treated by care-

prognosis. A large lesion extending across the

fully gauged doses of steroids, but this should

cornea, especially across the optical axis (i.e., the

be under strict ophthalmological supervision.

centre of the cornea), is likely to be the one that

In more severe cases, secondary iritis or sec-

is going to give trouble and it is better that the

ondary glaucoma can complicate the picture

patient should be warned about it at this stage.

and require special treatment. The decision

Common Eye Diseases and their Management

My eye seemed much better at first

on those steroid drops.

Figure 6.12. a Dendritic ulcer of cornea. b Use of steroid drops in herpes simplex keratitis. c Progression of herpes simplex keratitis

following use of steroid eye drops (with acknowledgement to Professor H. Dua).

whether or not to apply a pad to the eye depends

cornea can become numb and there is a high

on the state of the corneal epithelium and also

risk of corneal ulceration. Such neurotropic

on the patient’s response. In the worst cases, it

ulcers are characteristically painless and easily

might be advisable to perform a tarsorrhaphy,

become infected, with possible disastrous res-

that is to say, the lids are stitched together in

ults. A tarsorrhaphy might be needed to save the

such a way that they remain closed when the

eye but sometimes a soft contact lens can

stitches are removed. An alternative is to induce

suffice, provided the ulcer is not infected at

drooping of the eyelid by an injection of botu-

the time. Before embarking on the treatment of

linum toxin into the levator muscle. Surpris-

an anaesthetic cornea, the cause should be

ingly, the keratitis seems to heal usually in one

established and this may involve a full neuro-

to two weeks when this is done and the patient

logical investigation.

may be able to return to work, providing the

work, does not require the use of both eyes.

Owing to Exposure

When herpetic keratitis has taken its toll,

leaving a scarred cornea, the sight can even-

When the normal “windscreen wiper” mech-

tually be restored again by a corneal graft.

anism of the lids is faulty, as, for example, when

Unfortunately, recurrences still often occur and

the eyelids have been injured or in a case of

dendritic ulcers might appear on the graft.

facial palsy, the surface of the cornea can dry

and become ulcerated. The same problem

occurs in the unconscious patient unless great

Owing to Damage to the Corneal Nerve Supply

care is taken to keep the eyelids closed. Most

When the ophthalmic division of the trigeminal

cases of Bell’s palsy recover sufficiently quickly

nerve is damaged by disease or injury, the

to prevent exposure keratitis, but when severe

Common Diseases of the Conjunctiva and Cornea

and when recovery is poor, a tarsorrhaphy, or at

least treatment with an eye pad and local anti-

biotic ointment at night, might be needed. Bot-

ulinum toxin injection into the lid may obviate

the need for surgery; this has the effect of drop-

ping the upper lid for approximately three

months, and is a useful temporising measure in

some cases. It is important to bear in mind that

the same risk of corneal exposure is evident in

patients with severe thyrotoxic exophthalmos.

Corneal Dystrophies

Figure 6.13. Keratoconus; Placido’s disc image.

There are a number of specific corneal dystro-

phies, most of which are inherited and most of

which cannot be diagnosed without the aid of

the slit-lamp microscope. For this reason, they

him so that one can look down on his down-

will not be dealt with in any detail here. A list

turned eye. By holding up the upper lids, one

for reference is shown in Table 6.1.

can make an estimate of the abnormal shape of

Keratoconus (or conical cornea) is perhaps

the cornea by noting how the cornea shapes the

the commonest. It is still rare in the general pop-

lower lid. Alternatively, the patient’s cornea can

ulation but is familiar to general practitioners

be observed using Placido’s disc. This ingenious

looking after student populations because it

instrument is simply a disc with a hole in the

tends to appear in this age group. The condition

centre, through which one observes the patient’s

is bilateral and can be inherited as an autosomal

cornea. On the patient’s side of the disc is a

recessive trait, although most patients do not

series of concentric circles, which can be seen by

have a positive family history. It should be sus-

the observer reflected on the patient’s cornea

pected in patients who show a rapid change of

(Figure 6.13). Distortion of these circles ind-

refractive error, particularly if a large amount of

icates the abnormal shape of the cornea. Of

myopic astigmatism suddenly appears. Often,

course, more accurate assessment of the cornea

but not always, there is an associated history of

can be made by observing it with the slit-lamp

asthma and hay fever. The cornea shows central

microscope and still more information can be

thinning and protrudes anteriorly. This can be

obtained by keratometry or corneal topography,

observed with the naked eye by asking the

that is, using an instrument to measure the

patient to sit down and then standing behind

curvature of the cornea in different meridians.

Keratoconus tends to progress slowly and

contact lenses can be helpful. Sometimes a

Table 6.1. Corneal dystrophies.

corneal graft is required. Less common corneal

Anterior dystrophies (corneal epithelium and

dystrophies include Fuch’s endothelial, stromal

Bowman’s membrane):

and anterior dystrophies.

Microcystic

Reis Buckler’s

Stromal dystrophies:

Corneal Degenerations

Lattice

Macular

Granular

Apart from the inherited corneal dystrophies,

Posterior dystrophies (corneal endothelium and

certain changes are often seen in the cornea

Descemet’s membrane):

with ageing, such as arcus senilis and endothe-

Fuch’s

lial pigmentation. Band degeneration refers to a

Posterior polymorphous

deposition of calcium salts in the anterior layers

Ectatic dystrophies:

of the cornea. The calcification is first seen at the

Keratoconus

margin of the cornea in the nine o’clock and

Keratoglobus

three o’clock area, but it can gradually extend

Common Eye Diseases and their Management

• Trauma

• Contact lenses

• Postoperative

• Fuch’s endothelial dystrophy.

When the intraocular pressure is suddenly

raised from any cause, the cornea becomes

oedematous. The normal cornea needs to be

relatively dehydrated in order to maintain its

transparency, and the necessary level of dehyd-

ration seems to depend on active removal of

water by the corneal endothelium, as well as an

adequate oxygen supply from the tears. The

Figure 6.14. Band keratopathy.

mechanism is impaired not only by raising the

intraocular pressure, but also by infection or

trauma. Senile degenerative changes might also

be the sole underlying cause because of failure

across the normally exposed part of the cornea.

of the endothelial pumping mechanisms.

It is seen in cases of chronic iridocyclitis, in par-

Contact lenses, if ill fitting and worn for too long

ticular in patients with juvenile rheumatoid

a period, can prevent adequate oxygen reaching

arthritis and also in those with sarcoidosis. In

the cornea, with resulting oedema.

fact, band degeneration is seen in any eye that

The management of corneal oedema depends

has become degenerate or in cases of long-

on the management of the underlying cause.

standing corneal disease (Figure 6.14). Although

Oedema due to endothelial damage can respond,

band degeneration can, if sufficiently advanced,

in its early stages, to local steroids and some-

be diagnosed quite easily with the naked eye,

times a clear cornea can be maintained by the

most degenerative conditions of the cornea can

use of osmotic agents, such as hypertonic saline

only be diagnosed and classified under the

or glycerol. Chronic corneal oedema tends to be

microscope. Other corneal degenerations

painful and often acute episodes of pain occur

include Salzmann’s nodular dystrophy and

when bullae rupture leaving exposed corneal

lipid keratopathies.

nerves. In such cases, it can be necessary to con-

sider a tarsorrhaphy, or in some instances, a

corneal graft can prove beneficial. The pain of

Corneal Oedema

corneal oedema is a late symptom and in its

early stages, oedema simply causes blurring of

To the naked eye, corneal oedema might not be

the vision and the appearance of coloured

obvious but careful inspection will reveal a

haloes around light bulbs. This is simply

lack of luster when the affected cornea is com-

“bathroom window” effect. Patients with

pared with that on the other side. The normal

cataracts also see haloes, so that defects in other

sparkle of the eye is no longer evident and the

parts of the optical media of the eye might give

iris becomes less well defined. Microscopically,

a similar effect.

a bedewed appearance is seen, minute droplets

being evident in the epithelium. When the

stroma is also involved, this can seem misty and

Absent Corneal Sensation

might also be infiltrated with inflammatory

cells, which are seen as powdery white dots.

Corneal sensation is supplied by the fifth nerve.

When the oedema is long-standing, the droplets

About 70 nerve fibres are present in the super-

in the epithelium coalesce to produce blisters

ficial layers of the cornea and they can often be

or bullae.

seen when the cornea is examined with the slit-

The more important causes of corneal

lamp microscope. They appear as white threads

oedema are as follows:

running mainly radially. Asking the patient to

• Acute narrow-angle glaucoma

gaze straight ahead and then lightly touching

• Virus keratitis

the cornea with a fine wisp of cotton-wool can

Common Diseases of the Conjunctiva and Cornea

assess corneal anaesthesia. Care must be taken

not to touch the lid margins when doing this.

The blink reflex is then noted and it is also

important to ask the patient what has been felt.

In the case of elderly people, the blink reflex

might be reduced, but a slight prick should be

evident when the cornea is touched. Attempts

to quantify corneal anaesthesia have led to the

development of graded strengths of bristle,

which can be applied to the cornea instead

of cotton-wool.

Corneal anaesthesia can result from a lesion

at any point in the fifth cranial nerve from the

cornea to the brainstem. In the cornea itself,

Figure 6.15. Herpes zoster ophthalmicus.

herpes simplex infection can ultimately result in

anaesthesia. Herpes zoster is especially liable

to lead to this problem and, because this con-

dition can often be treated at home rather

than in the ward, it will be considered in more

occurs with remarkably little scarring of the

detail here.

skin considering the appearance in the acute

stage. However, the cornea can be rendered per-

manently anaesthetic and the affected area of

Herpes Zoster Ophthalmicus

skin produces annoying paresthesiae, amount-

ing quite often to persistent rather severe neu-

This is caused by the varicella-zoster virus, the

ralgia, which can dog the patient for many years.

same virus that causes chickenpox. It is thought

Other complications include extraocular muscle

that the initial infection with the virus occurs

palsies or rarely, encephalitis. Iridocyclitis is

with an attack of childhood chickenpox and that

fairly common and glaucoma can develop and

the virus remains in the body in a latent form,

lead to blindness if untreated. At present, there

subsequently to manifest itself as herpes zoster

is no known effective treatment other than the

in some individuals. The virus appears to lodge

use of local steroids and acyclovir for the

in the Gasserian ganglion. The onset of the con-

uveitis, and acetazolamide or topical beta-

dition is heralded by headache and the appear-

blockers for the glaucoma. Administration of

ance of one or two vesicles on the forehead. Over

systemic acyclovir or famciclovir early in the

the next three or four days the vesicles multiply

disease is known to reduce the severity of the

and appear on the distribution of one or all of

neuralgia, but these medications need to be

the branches of the fifth cranial nerve. The

administered as soon as possible after the onset

patient can develop a raised temperature and

of symptoms for best effect. The disease has to

usually experiences malaise and considerable

run its course and the patient, who is usually

pain. Sometimes a chickenpox-like rash appears

elderly, could require much support and advice,

over the rest of the body. The eye itself is most

especially when post-herpetic neuralgia is

at risk when the upper division of the fifth nerve

severe. It is accepted practice to treat the eye at

is involved. There might be vesicles on the lids

risk with antibiotic drops and a weak mydriatic.

and conjunctiva and, when the cornea is

Analgesics are, of course, also usually needed,

affected, punctate-staining areas are seen, which

often on a long-term basis.

become minute subepithelial opacities. After

Other causes of corneal anaesthesia include

four days to a week, the infection reaches its

surgical division of the fifth cranial nerve for

peak; the eyelids on the affected side might be

trigeminal neuralgia or any space-occupying

closed by swelling, and oedema of the lids might

lesion along the nerve pathway. The possibility of

spread across to the other eye (Figure 6.15). The

exposure and drying of the cornea must always

vesicles become pustular and form crusts,

be borne in mind in the unconscious or the

which are then shed over a period of two or

anaesthetized patient because corneal ulceration

three weeks. In most cases, complete resolution

and infection will soon result if this is neglected.

The Red Eye

Redness of the eye is one of the commonest

Red Eye That Is Not Painful

signs in ophthalmology, being a feature of a

wide range of ophthalmological conditions,

and Sees Normally

some of which are severe and sight threatening,

whereas others are mild and of little cons-

Subconjunctival Haemorrhage

equence. Occasionally, the red eye can be the

Careful examination of the eye will easily

first sign of important systemic disease. It is

confirm that its redness is due to blood rather

important that every practicing doctor has an

than dilated blood vessels, and the redness

understanding of the differential diagnosis of

might be noticed by someone other than the

this common sign, and a categorisation of the

patient. The condition is common and resolves

signs, symptoms and management of the red

in about 10-14 days. It is extremely unusual for

eye will now be made from the standpoint of the

a blood dyscrasia to present with subconjunc-

nonspecialist general practitioner.

tival haemorrhages. Although vomiting or a

The simplest way of categorising these

bleeding tendency can also be rare causes,

patients is in terms of their visual acuity. As a

the normal practice is to reassure the patient

general rule, if the sight, as measured on the

rather than embark on extensive investigations,

Snellen test chart, is impaired, then the cause

because the majority of cases are caused by

might be more serious. The presence or absence

spontaneous bleeding from a conjunctival cap-

of pain is also of significance, but as this

illary. This might be spontaneous and can result

depends in part on the pain threshold of the

from a sudden increase in venous pressure, for

patient, it can be a misleading symptom.

example after coughing.

Disease of the conjunctiva alone is not usually

painful, whereas disease of the cornea or iris is

generally painful.

Conjunctivitis

The red eye will, therefore, be considered

under three headings: the red eye that sees well

Examination of the eye reveals inflammation,

and is not painful, the red painful eye that can

that is, dilatation of the conjunctival capillaries

see normally, and the red eye that does not see

and larger blood vessels, associated with more

well and is acutely painful.

or less discharge from the eye. The exact site of

Common Eye Diseases and their Management

the inflammation should be noted and it is esp-

symptoms to be elicited and these can be related

ecially useful to note whether the deeper capil-

to a checklist of causes mentioned below.

laries around the margin of the cornea are

The key symptoms of chronic conjunctivitis

involved. The resulting pink flush encircling the

are as follows:

cornea is called “ciliary injection” and is a

• Environmental factors, especially eye

warning of corneal or intraocular inflam-

drops, make-up or foreign bodies.

mation. For clinical purposes, it is useful to

divide conjunctivitis into acute and chronic

• Lids stick in mornings?

types.

• Do the eyes itch?

• Emotional stress or psychiatric illness?

Acute Conjunctivitis

The following is a checklist of causes of

This is usually infective and caused by a bac-

chronic conjunctivitis:

terium; it is more common in young people. It

can spread rapidly through families or schools

•

Eyelids: deformities, such as entropion or

without serious consequence other than a few

ectropion.

days incapacity. When adults develop acute con-

•

Displaced eyelashes.

junctivitis, it is worth searching for a possible

•

Chronic blepharitis.

underlying cause, especially a blocked tear duct

•

Refractive error: a proportion of patients

if the condition is unilateral. Sometimes an

who have never worn glasses and need

ingrowing lash might be the cause or occasion-

them or who are wearing incorrectly pre-

ally a free-floating eyelash lodges in the lacrimal

scribed or out-of-date glasses present with

punctum. The important symptoms of acute

the features of chronic conjunctivitis, the

conjunctivitis are redness, irritation and stick-

symptoms being relieved by the proper use

ing together of the eyelids in the mornings.

of spectacles. The cause is not clear but

Management entails finding the cause and using

possibly related to rubbing the eyes.

antibiotic drops if the symptoms are severe

•

Dry eye syndrome: the possibility of a

enough to warrant this. However, it must be

defect in the secretion of tears or mucus can

remembered that the inadequate and intermit-

only be confirmed by more elaborate tests,

tent use of antibiotic eye drops could simply

but this should be suspected in patients

encourage growth of resistant organisms.

with rheumatoid arthritis or sarcoidosis.

•

Foreign body: contact lenses and mascara

Chronic Conjunctivitis

particles are the commonest foreign

This is a common cause of the red eye and almost

bodies to cause chronic conjunctivitis.

a daily problem in nonspecialised ophthalmic

•

Stress: often a period of stress seems to

practice. If we consider that the conjunctiva is a

be closely related to the symptoms and

mucous membrane that is exposed daily to the

perhaps eye rubbing is also the cause in

elements, it is perhaps not surprising that after

these patients.

many years it tends to become chronically

•

Allergy: it is unusual to be able to incrim-

inflamed and irritable. The frequency and

inate a specific allergen for chronic con-

nuisance value of the symptoms are reflected

junctivitis, unlike allergic blepharitis. On

in the large across-the-counter sales of various

the other hand, hay fever and asthma could

eyewashes and solutions aimed at relieving “eye-

be the background cause.

strain” or “tired eyes”. The symptoms of chronic

conjunctivitis are, therefore, redness and irrita-

•

Infection: chronic conjunctivitis can begin

tion of the eyes, with a minimal degree of dis-

as an acute infection, usually viral and

charge and sticking of the lids. If there is an

usually following an upper respiratory

allergic background, itching might also be a

tract infection.

main feature. The chronically inflamed conjunc-

•

Drugs: the long-term use of adrenaline

tiva accumulates minute particles of calcium

drops can cause dilatation of the conjunc-

salts within the mucous glands. These conjunc-

tival vessels and irritation in the eye. In

tival concretions are shed from time to time, pro-

1974, it was shown that the beta-blocking

ducing a feeling of grittiness. When confronted

drug practolol (since withdrawn from the

with such a patient, there are a number of key

market) could cause a severe dry eye

The Red Eye

syndrome in rare instances. Since then

there have been several reports of mild

reactions to other available beta-blockers,

although such reactions are difficult to

distinguish from chronic conjunctivitis

from other causes.

• Systemic causes: congestive cardiac failure,

renal failure,Reiter’s disease,polycythaemia,

gout, rosacea, as well as other causes of

orbital venous congestion, such as orbital

tumours, can all cause vascular congestion

and irritation of the conjunctiva. Migraine

can also be associated with redness of the

eye on one side and chronic alcoholism is a

cause of bilateral conjunctival congestion.

Figure 7.2. Scleritis.

Episcleritis

Sometimes the eye becomes red because of

Red Painful Eye That

inflammation of the connective tissue underly-

ing the conjunctiva, that is, the episclera. The

Can See Normally

condition can be localised or diffuse. There is no

discharge and the eye is uncomfortable,although

Scleritis

not usually painful. The condition responds to

sodium salicylate given systemically and to the

Inflammation of the sclera is a less

common

administration of local steroids or nonsteroidal

cause of red eye. There is no discharge but the

anti-inflammatory agents. The underlying cause

eye is painful. Vision is usually normal, unless

is often never discovered, although there is a

the inflammation involves the posterior sclera.

well-recognised link with the collagen and

It is most often seen in association with

dermatological diseases, especially acne rosacea.

rheumatoid arthritis and other collagen dis-

Episcleritis tends to recur and might persist for

eases and sometimes can become severe and

several weeks, producing a worrying cosmetic

progressive to the extent of causing perforation

blemish in a young person (Figure 7.1).

of the globe (Figure 7.2). For this reason, steroids

must be administered with extreme care. Treat-

ment normally is with systemically adminis-

tered nonsteroidal anti-inflammatory agents,

for example flurbiprofen (Froben) tablets.

Red Painful Eye That

Cannot See

It is worth emphasising again that the red

painful eye with poor vision is likely to be a

serious problem, often requiring urgent admis-

sion to hospital or at least intensive outpatient

treatment as a sight-saving measure. The fol-

lowing are the principal causes.

Acute Glaucoma

Figure 7.1. Episcleritis (with acknowledgement to Professor

The important feature here is that acute glau-

H. Dua).

coma occurs in long-sighted people and there is

Common Eye Diseases and their Management

usually a previous history of headaches and

seeing haloes around lights in the evenings. The

raised intraocular pressure damages the iris

sphincter and for this reason, the pupil is semi-

dilated. Oedema of the cornea causes the eye to

lose its luster and gives the iris a hazy appear-

ance (Figure 7.3). The eye is extremely tender

and painful and the patient could be nauseated

and vomiting. Immediate admission to hospital

is essential, where the intraocular pressure is

first controlled medically and then bilateral

laser iridotomies or surgical peripheral iridec-

tomies are performed to relieve pupil block.

Mydriatics should not be given to patients with

Figure

7.4. Acute iritis. The pupil has been dilated with

suspected narrow-angle glaucoma without con-

drops.

sultation with an ophthalmologist.

sarcoidosis or ankylosing spondylitis. The

condition lasts for about two weeks but tends

Acute Iritis

to recur over a period of years. After two or

three recurrences there is a high risk of the

The eye is painful, especially when attempting

development of cataract, although this might

to view near objects, but the pain is never so

form slowly.

severe as to cause vomiting. The cornea remains

bright and the pupil tends to go into spasm and

is smaller than on the normal side (Figure 7.4).

Acute Keratitis

Acute iritis is seen from time to time mainly in

the 20-40-year age group, whereas acute glau-

The characteristic features are sharp pain, often

coma is extremely rare at these ages. Unless

described as a foreign body in the eye, marked

severe and bilateral, acute iritis is treated on an

watering of the eye, photophobia and difficulty

outpatient basis with local steroids and mydria-

in opening the affected eye. The clinical picture

tic drops. Some expertise is needed in the use

is different from those of the above two cond-

of the correct mydriatic, and systemic steroids

itions and the commonest causes are the herpes

should be avoided unless the sight is in jeop-

simplex virus or trauma. The possibility of a

ardy. Because the iris forms part of the uvea,

perforating injury must always be borne in

acute iritis is the same as acute anterior uveitis.

mind. Sometimes children are reticent about

In many cases, no systemic cause can be found

any history of injury for fear of incriminating a

but it is important to exclude the possibility of

friend, and sometimes a small perforating

injury is surprisingly painless. The treatment of

acute keratitis has already been discussed in

Chapter

6 and the management of corneal

injuries will be considered in Chapter 16.

Neovascular Glaucoma

The elderly patient who presents with a blind

and painful eye and who might also be diabetic

should be suspected of having neovascular glau-

coma. Often, a fairly well-defined sequence of

events enables the diagnosis to be inferred from

the history, as in many cases secondary neo-

vascular glaucoma arises following a central

retinal vein occlusion. Following retinal vein

occlusion, patients typically notice that the

Figure 7.3. Acute angle-closure glaucoma.

vision of one eye becomes blurred over several

Failing Vision

Failing vision means that the sight, as measured

Failing Vision in an Eye That

by the standard test type, is worsening. The

patient might say “I can’t see so well doctor” or

Looks Normal

they might feel that their spectacles need chang-

ing. Some patients might not notice visual loss,

especially if it is in one eye. Sometimes, more

When the Fundus Is Normal

specific symptoms are given; the vision might be

blurred, for example in a patient with cataract, or

Often a patient will present with a reduction of

objects might appear distorted or straight lines

vision in one or both eyes and yet the eyes them-

bent if there is disease of the macular region of

selves look quite normal. In the case of a child,

the retina. Disease of the macular can also make

the parents may have noticed an apparent

objects look larger or smaller. Double vision is an

difficulty in reading or the vision may have been

important symptom because it can be the result

noticed to be poor at a routine school eye test.

of a cranial nerve palsy, but if monocular, it could

The next step is to decide whether the fundus is

be caused by cataract. Patients quite often com-

also normal, but before dilating the pupil to

plain of floating black spots. If these move slowly

allow fundus examination, it is important to

with eye movement, they might be caused by

check the pupil reactions and to eliminate the

some disturbance of the vitreous gel in the centre

possibility of refractive error. Once the glasses

of the eye. If they are accompanied by seeing

have been checked and the fundus examined,

flashing lights, the possibility of damage to the

the presence of a normal fundus narrows the

retina needs to be kept in mind. “Vitreous

field down considerably. The likely diagnosis

floaters” are common and in most instances are

depends on the age of the patient. Infants with

of little pathological significance. Patients quite

visual deterioration might require an examina-

often notice haloes around lights and, although

tion under anaesthesia to exclude the possibil-

this is typical of an attack of acute glaucoma,

ity of a rare inherited retinal degeneration or

haloes are also seen by patients with cataracts.

other retinal disease. Other children, particu-

Like many such symptoms, they are best not

larly those in the 9-12-year age group, must first

asked for specifically. The question “do you ever

be suspected of some emotional upset, perhaps

see haloes?” is likely to be followed by the answer

due to domestic upheaval or stress at school.

“yes”. Night blindness is another such symptom.

This can make them reluctant to read the test

No one can see too well in the dark,but if a patient

type. Sometimes such children discover that

has noticed a definite worsening of his or her

exercising their own power of accommodation

ability to see in dim light, an inherited retinal

produces blurring of vision and they might

degeneration, such as retinitis pigmentosa,

present with accommodation spasm. The

might be the cause.

commonest cause of unilateral visual loss in

Common Eye Diseases and their Management

children is amblyopia of disuse. This important

limited to the eye itself, but disease elsewhere in

cause of visual loss with a normal fundus is con-

the body can often first present as a visual

sidered in more detail in Chapter 14 on squint.

problem. In this context, we must remember

When, for any reason, one retina fails to receive

what has been the commonest cause of blind-

a clear and correctly orientated image for a

ness in young people - diabetic retinopathy, as

period of months or years during the time of

well as the occasional case of severe hyper-

visual development, the sight of the eye remains

tension. Intracranial causes of visual loss are

impaired. The condition is treatable if caught

perhaps less common in general practice and,

before the visual reflexes are fully developed,

for this reason, are easily missed. Intracranial

that is, before the age of eight years. Young

tumours can present in an insidious manner, in

adults who present with unilateral visual loss

particular the pituitary adenoma, and the diag-

and normal fundi could, of course, have

nosis might be first suspected by careful plot-

amblyopia of disuse and the condition can be

ting of the visual fields. In the case of the elderly

confirmed by looking for a squint or a refractive

patient who complains of visual deterioration in

error more marked on the affected side. We

one eye, the ophthalmoscope all too commonly

must also remember that retrobulbar neuritis

reveals age-related macular degeneration, but

presents in young people as sudden loss of

it is also common to find that the patient has

vision on one side with aching behind the

suffered a thrombosis of the central retinal

eye and a reduced pupil reaction on the

vein or one of its branches. Unlike the situa-

affected side. This contrasts with amblyopia

tion with a central retinal artery occlusion,

of disuse, in which the pupil is normal.

which is less common, some vision is pre-

Migraine is another possibility to be considered

served with a central retinal vein thrombosis in

in such patients.

spite of the dramatic haemorrhagic fundus

Elderly patients who present with visual loss

appearance. Temporal arteritis is another

and normal fundi might give the history of a

important vascular cause of visual failure in

stroke and are found to have a homonymous

the elderly.

haemianopic defect of the visual fields caused

Finally, there are a large number of less

by an embolus or thrombosis in the area of dis-

common conditions, only one or two of which

tribution of the posterior cerebral artery.

will be mentioned at this point. At any age, the

Hysteria and malingering are also causes of

ingestion of drugs can affect the eyesight, but

unexplained visual loss, but these are extremely

there are very few proven oculotoxic drugs

rare and it is important that the patient is

still on the market. One important example is

investigated carefully before such a diagnosis

chloroquine. When a dose of 100 g in one year is

is made.

exceeded, there is a risk of retinotoxicity, which

might not be reversible. Although age-related

macular degeneration is normally seen in the

over-60s, the same problem may occur in

younger people often with a recognised inherit-

When the Fundus Is Abnormal

ance pattern. A completely different condition

Quite a proportion of patients who complain of

can also affect the macular region of young

loss of vision with eyes that look normal on

adults, known as central serous retinopathy.

superficial inspection show changes on ophthal-

This tends to resolve spontaneously after a

moscopy. The three important potentially blind-

few weeks, although treatment by laser coag-

ing but eminently treatable ophthalmological

ulation is occasionally needed. Unilateral pro-

conditions must be borne in mind: cataract,

gressive visual loss in young people can also

chronic glaucoma and retinal detachment. It is

be caused by posterior uveitis, which is the same

an unfortunate fact that the commonest cause of

as choroiditis. The known causes and manage-

visual loss in the elderly is usually untreatable

ment of this condition will be discussed in

at the present time. It is known as age-related

Chapter 18.

macular degeneration and forms part of the

The more common causes of failing vision

sensory deprivation, which is an increasing

in a normal-looking eye are summarised in

scourge in elderly people. These diseases are

Table 8.1.

Failing Vision

Table 8.1. Failing vision in a normal-looking eye.

Fundus normal

Fundus abnormal

Child

Refractive error

Cataract

Disuse amblyopia

Macular degeneration

Inherited retinal degeneration

Posterior uveitis

Emotional stress

Young adult

Refractive error

Diabetic retinopathy

Retrobulbar neuritis

Retinal detachment

Intracranial space-occupying lesion

Macular disease

Drug toxicity

Hypertension

Posterior uveitis

Elderly

Homonymous haemianopia

Macular degeneration

Central vein thrombosis

Chronic glaucoma

Cataract

Vitreous haemorrhage

Temporal arteritis

applied steroids also play a sight-saving role in

Treatable Causes of

the management of temporal arteritis in the

Failing Vision

elderly and in the treatment of uveitis. In recent

years, the treatment of diabetic retinopathy has

Nobody can deny that the practice of ophthal-

been greatly advanced by the combined effect

mology is highly effective. Many eye diseases

of laser coagulation and scrupulous control of

can be cured or arrested, and it is possible to

diabetes. In the past, about one-half of patients

restore the sight fully from total blindness.

with the proliferative type of retinopathy would

Many of the commoner causes of blindness,

be expected to go blind over five years and many

especially in the third world, are treatable. The

of these were young people at the height of their

most important treatable cause of visual failure

in the UK is cataract, and, of course, no patient

should be allowed to go blind from this cause,

although this does occasionally happen (Figure

8.1). Retinal detachment is less common than

cataract but it provides a situation where the

sight could be lost completely and then be fully

restored. For the best results, surgery must be

carried out as soon as possible, before the retina

becomes degenerate, whereas delay before

cataract surgery does not usually affect the

outcome of the operation. Acute glaucoma is

another instance where the sight could be lost

but restored by prompt treatment. The treat-

ment of chronic glaucoma has less impression

on the patient because it is aimed at preventing

visual deterioration, although in sight-saving

terms it can be equally effective.

It is easy to overlook the value of antibiotics

in saving sight. Before their introduction,

many more eyes had to be removed following

injury and infection. Systemic and locally

Figure 8.1. The family thought it was just old age.

Common Eye Diseases and their Management

careers. The proper management of ocular

it accounts for loss of reading vision in many

trauma often has a great influence on the visual

elderly people. Some myopic patients are sus-

result, and the rare but dreaded complication

ceptible to degeneration of the retina in later

of ocular perforating injuries

- sympathetic

years; known as myopic chorioretinal degener-

ophthalmia - can now be treated effectively

ation, it can account for visual deterioration in

with systemic steroids. Amblyopia of disuse has

myopes who have otherwise undergone suc-

already been mentioned; the treatment is

cessful cataract or retinal surgery.

undoubtedly effective in some cases but the

Scarring of the retina following trauma is

results are disappointing if the diagnosis is

another cause of permanent and untreatable

made when the child is too old or when there is

visual loss, but the most dramatic and irrevoca-

poor patient co-operation.

ble loss of vision occurs following traumatic

section of the optic nerve. One must be careful

here before dismissing the patient as untreat-

able because on rare occasions a contusion

Untreatable Causes of

injury to the eye or orbit can result in a haem-

Failing Vision

orrhage into the sheath of the optic nerve. Some

degree of visual recovery can sometimes occur

Ophthalmologists are sometimes asked if the

in these patients and it has been claimed that

sight can be restored to a blind eye and, as a

recovery might be helped by surgically opening

general rule, one can say that if there is no per-

the nerve sheath. There is one odd exception

ception of light in the eye, it is unlikely that the

to this dramatic form of blindness that can

sight can be improved, irrespective of the cause.

follow optic nerve insult: visual loss due to optic

There are several ophthalmological conditions

neuritis. Patients with retrobulbar neuritis

for which there is no known effective treatment

(optic neuritis) nearly always recover their

and it is sometimes important that the patient

vision again, whether or not they receive treat-

is made aware of this at an early stage in order

ment. The explanation is that the visual loss is

to avoid unnecessary anxiety, and perhaps

caused by pressure from oedema rather than to

unnecessary visits to the doctor. Most degener-

damage to the nerve fibres themselves. It is

ative diseases of the retina fail to respond to

hardly necessary to say that any neurological

treatment. If the retina is out of place, it can be

damage proximal to the optic nerve tends to

replaced, but old retinae cannot be replaced

produce permanent and untreatable visual

with new. So far, there has been no firm evidence

loss, as exemplified by the homonymous

that any drug can alter the course of inherited

haemianopic field defect that can follow a

retinal degenerations, such as retinitis pigmen-

cerebrovascular accident.

tosa, although useful information is beginning

Malignant tumours of the eye come into this

to appear about the biochemistry and genetics

category of untreatable causes of visual failure

of these conditions. Age-related macular degen-

but in fact serious attempts are now being made

eration tends to run a progressive course in

to treat them with radiotherapy in specialised

spite of any attempts at treatment, and although

units and the prognosis appears to be improv-

most patients do not become completely blind,

ing in some cases.

Headache

Headache must be one of the commonest symp-

tend not to have an organic basis; the patient

toms, and few specialities escape from the diag-

with an organic headache is not usually smi-

nostic problems that it can present. We must

ling. The time of day could be important: raised

begin with the realisation that more or less

intracranial pressure has the reputation of

everyone suffers from headache at some time or

causing an early morning headache, which is

other. In fact, the majority of headaches that

described as bursting or throbbing and can be

present have no detectable cause and are often

made worse by straining or coughing. We must

labelled psychogenic if there seems to be a back-

always remember the triad of headache, vomit-

ground of stress. The implication is that the suf-

ing and papilloedema in this respect, especially

ferer is perhaps exaggerating mild symptoms in

as the vomiting might not be accompanied

order to gain sympathy from his or her spouse,

by nausea, and is not necessarily mentioned

or even perhaps the doctor. One must, of course,

by the patient. The family history should also

be extremely cautious about not accepting

be noted, especially where there is a history

symptoms at their face value, and certainly

of migraine.

cerebral tumours have been overlooked for this

reason. If the psychogenic headache is the com-

monest, then the headache caused by raised

Classification

intracranial pressure and a space-occupying

lesion must be the most important. Between

When considering the different common causes

these two, the whole spectrum of causes must be

of headache, an anatomical classification is a

considered. It is essential, therefore, to memo-

useful way of providing a reference list. The

rise a permanent checklist in order that obvious

following should be considered by the

causes are not omitted.

examining doctor.

Cerebrospinal Fluid

History

A rise or fall from normal of the cerebrospinal

Often the history is the total disease in the

fluid pressure is associated with headache.

absence of any physical signs and it is important

When the pressure of the cerebrospinal fluid is

to note the nature of the pain, the total duration

raised, the patient usually experiences a burst-

and frequency of the pain, the time of day it

ing pain, which can interrupt sleep or appear in

occurs, and its relation to other events or the

the early morning. It tends to be intermittent

taking of analgesics. Headaches that are present

and is made worse by coughing or lying down.

“all the time” and are described in fanciful terms

It can also, of course, be accompanied by

Common Eye Diseases and their Management

papilloedema and vomiting, and another

oping normal tension glaucoma two- or four-

important symptom is blurring and transient

fold. Interestingly, migraine is one of the few

obscurations of vision. The situation of the

risk factors for this condition.

pain is usually diffuse rather than focal, but we

There is some doubt as to whether essential

must remember that a bursting headache made

hypertension causes headaches, but there is no

worse by coughing is sometimes described by

doubt that when the blood pressure becomes

otherwise healthy individuals. When the

acutely raised, a severe headache may ensue,

rise of intracranial pressure is caused by a

accompanied by blurring of vision. Any adults

space-occupying lesion, signs of focal brain

with headaches should have their blood pres-

damage can also be present.

sure measured. Another form of headache

associated with abnormality of the blood

vessels is that caused by an intracranial

Blood Vessels

aneurysm of the internal carotid artery or one

A variety of diseases involving the blood vessels

of its branches. The pain in this case is usually

can cause headache. The commonest is prob-

throbbing in nature and there might be other

ably migraine. Classical migraine is thought to

signs of a space-occupying lesion at the apex of

be caused by an initial spasm followed by dilata-

the orbit, for example a cranial nerve palsy or a

tion of the meningeal arteries. There is usually

bruit heard with the stethoscope. In the case of

a family history of the same problem showing

elderly patients, the possibility of giant cell

dominant inheritance, and attacks can some-

arteritis must always be kept in mind. This is an

times be precipitated by stress or taking certain

inflammation of the walls of many of the

foods, such as cheese. Before the headache

medium-sized arteries in the body, but it tends

begins, there is usually a visual aura charac-

to affect the temporal arteries preferentially. The

terised by a shimmering effect before one or

walls of the vessels become thickened by

both eyes, which spreads across the vision, or

inflammatory cells and giant cells mainly in the

the appearance of zig-zag lines known as

media and there is fibrosis of the intima (Figure

fortifications because of their resemblance to

9.1). The lumen of the affected vessels becomes

the silhouette of a fortress. The visual distur-

occluded. Affected patients are usually over the

bance can take the form of a hemianopic

age of 70 years and complain of tenderness of

scotoma or, rarely, of a formed hallucination

the scalp, especially over the temporal arteries,

but, whatever their nature, they tend to last for

which can be seen and felt to be inflamed, and

about 10-20 min and are followed by a headache

typically no pulse can be felt in them. The

that is centred above the eye and is described

headache is made particularly bad by brushing

as a boring pain. The headache lasts for any time

the hair and other systemic symptoms include

between 1 h and 24 h and then disperses. The

jaw claudication, weight loss and malaise. The

patient might experience nausea and vomiting

as the attack ends. Migraine can begin quite

early in childhood and continue at regular inter-

vals for many years. Migraines are more

common in women and tend to improve at the

time of the menopause. Atypical migraine can

sometimes pose a diagnostic problem. The

visual aura might appear by itself or the

migraine attack might be accompanied by

gastrointestinal symptoms or by ophthalmople-

gia. The attack might be preceded by oliguria

and fluid retention and be followed by a

diuresis. Rarely, a permanent hemianopic

scotoma or ophthalmoplegia can result from an

attack of migraine, but in these circumstances

Figure 9.1. Cross-section of the temporal artery from patient

the original diagnosis must be reviewed care-

with temporal arteritis. The artery is almost occluded. Note

fully. Of some importance is the fact that a

the large number of giant cells (with acknowledgement to

history of migraine increases the risk of devel-

Dr J. Lowe).

Headache

importance of this type of headache rests on the

merges with cluster headache, being described

fact that the eye is involved in about 60% of

as severe ocular pain associated with meiosis

cases and the patient can suddenly go blind in

and ptosis. Trigeminal neuralgia can be easily

one eye and then a short time later go blind in

distinguished from these other forms of

the other. Patients with giant cell arteritis invar-

headache by its distribution over one or all of the

iably have a raised erythrocyte sedimentation

terminal branches of the trigeminal nerve and

rate (ESR) and C-reactive protein level (typi-

the fact that the severe pain is triggered by

cally the ESR is found to be above 70 mm/h). A

touching a part of the cheek or by chewing and

temporal artery biopsy is helpful in specific sit-

swallowing. The pain is so severe that the patient

uations to assist with the diagnosis, particularly

can become suicidal, and surgical division of the

in those with indeterminate clinical findings.

trigeminal nerve at the level of the Gasserian

When giant cell arteritis is first considered as a

ganglion has been a method of treatment.

diagnosis, it is advisable to start treatment with

Postherpetic neuralgia is an extremely debil-

systemic steroids without delay, before awaiting

itating form of headache experienced by elderly

confirmatory diagnosis on histology. Steroid

people after an attack of trigeminal herpes

treatment is effective in preventing blindness

zoster. The pain seems to be more severe in the

and is required usually for a

12-18-month

elderly and it can persist for many years. The

period. Once instituted, the response to treat-

cause of the headache is usually evident when

ment and the side effects should be very care-

one inspects the skin of the forehead, which is

fully monitored, preferably in co-operation with

slightly whitened and scarred from the previous

a general physician with regular measurement

attack of herpes zoster. Apart from the use of

of the ESR and other inflammatory markers.

analgesics, antidepressant drugs can also help,

Other less common vascular causes of headache

together with the application of local heat or

include intracranial angioma and subarachnoid

vibration massage. Fortunately, the prompt

or subdural haemorrhage.

treatment of the original attack of herpes zoster

at primary care level with systemic acyclovir

does seem to be reducing the incidence of this

Blood

troublesome condition.

Changes in the blood itself can also be asso-

ciated with headache. It is easy to forget that

Bones

anaemic patients often have headaches, which

can be cured by treating the anaemia. Likewise,

In Paget’s disease of bone, the bones of the head

patients with polycythaemia might also com-

enlarge and grow abnormally, the abnormal

plain of headache. Hypoglycaemia is another

growth being associated with headache and,

recognised cause; here, the symptoms occur

incidentally, an increase in hat size. The eyes

after strenuous exercise or insulin excess in a

themselves might show optic atrophy, and close

diabetic patient.

inspection of the fundi can reveal the curious

appearance of wavy lines known as angioid

streaks. Oxycephaly is a congenital defect of the

Nerves

skull caused by premature closure of the

In many respects, cluster headache resembles

sutures; patients sometimes complain of

migraine, although it is more common in men in

headache, as well as visual loss because of optic

the third or fourth decade. The word “cluster”

nerve compression. Multiple myeloma is the

refers to the timing of the attacks, which can be

name given to a malignant proliferation of

repeated several times over a few weeks, fol-

plasma cells within the bone marrow. There is

lowed by a period of remission for several

also an excessive production of immunoglobu-

months. The pain is described as being severe

lins. Osteolytic bone lesions occur especially in

and unilateral. There is conjunctival congestion

the skull, and headache can be an accompani-

and constriction of the pupil on the affected

ment. The disease is more common in the

side, and the attack can last from minutes to

elderly and is accompanied by a high ESR. Diag-

hours. Tenderness over the affected side of

nosis is made by examining the urine for

the face and nasal discharge are also features.

Bence-Jones proteins and the serum for abnor-

Raeder’s paratrigeminal neuralgia probably

mal immunoglobulins. Disease of the cervical

Common Eye Diseases and their Management

vertebrae is another cause of headache, because

commonly in adults aged 30-40 years who are

of the effect of spasm of the neck muscles. Relief

beginning to have difficulty in accommodating

of the pain by neck manipulation has been

through their long-sightedness. For reasons of

claimed, but the exact diagnosis must be made

vanity, patients might have been deliberately

before embarking on such treatment.

avoiding the use of glasses and it might have to

be explained to them that they have the choice

of having headaches or wearing glasses. In the

Meninges

patient with no refractive error, the onset of

It is presumed that the pain and headache that

presbyopia can be accompanied by headache,

accompany meningitis or encephalitis are

which is sometimes delayed until the morning

mediated through the sensory nerve supply to the

after prolonged reading. An otherwise normal

meninges. The pain-sensitive structures in the

person aged 45 years should be suspected of

middle and anterior cranial fossa are supplied by

having presbyopic headaches. Uncorrected

the fifth cranial nerve, and inflammation can

myopes do not usually complain of headaches.

produce referred pain to the region of the eye.

If the spectacle prescription is incorrect for

any reason, a sensitive person can experience

headache, but it is surprising how some people

The Eyes

will tolerate an incorrect spectacle lens without

The classical eye headache is that of subacute

complaint. Ocular muscle imbalance is an

narrow-angle glaucoma. Here, the headache is

uncommon cause of headache but it is an impor-

an evening one, tends to be over one eye and

tant one because it can be corrected with con-

is nearly always accompanied by blurring of

siderable relief to the patient. Usually, the patient

vision and seeing coloured haloes around street

shows a significant difference in refractive error

lights. If the intraocular pressure is measured

between the two eyes and when the eyes are

when the headache is present and is found to be

dissociated by such means as the cover test or

normal, it is unlikely that narrow-angle glau-

the Maddox wing test, one eye tends to drift

coma is the correct diagnosis. On the other

upwards or downwards. Relief of symptoms can

hand, the diagnosis cannot be so easily excluded

be achieved by incorporating a prism into the

if the headache is absent at the time of exam-

spectacle lens or, if the deviation is marked, by

ination. Patients with narrow-angle glaucoma

ocular muscle surgery. Horizontal imbalance of

are long-sighted - therefore, beware the middle-

the ocular movements is less closely linked with

aged, long-sighted patient with evening

headache, although there is a group of patients,

headaches and blurring of vision. Chronic

usually young adults under stress, who seem

open-angle glaucoma rarely causes headache

unable to converge their eyes on near objects;

because the rise of intraocular pressure is too

instead, they allow one eye to drift outwards

gradual and not great enough. The possibility

when reading. Some elderly patients have the

should be borne in mind when a patient exper-

same problem but do not so often have asso-

iences headaches following ocular trauma or

ciated headache. This so-called convergence

eye surgery, that there might be secondary glau-

insufficiency can be greatly improved by a

coma. This type of glaucoma often responds

course of convergence exercises and provides

well to treatment but if ignored, can lead rapidly

one of the few instances where exercises of the

to blindness. Acute iritis is associated with

eye muscles have any therapeutic value.

headache but in practice rarely presents as such

because the other ocular symptoms override

this. Patients developing endophthalmitis com-

Pain Referred from Other Sites

plain of severe pain in the eye and headache, this

being a particularly important symptom fol-

Sinusitis is well recognised as a common cause

lowing cataract surgery.

of headache and the patient with headache

It has been argued that refractive error does

should be questioned about recent upper res-

not cause headache, but nothing could be

piratory tract infections or a previous history of

further from the truth. Refractive headache is

sinus disease. Tenderness over the affected sinus

most commonly seen in uncorrected hyper-

is an important sign. The headache tends to

metropes, sometimes in children, but more

begin after rising in the morning and reaches a

Headache

peak later in the morning. Pain from an infected

do sometimes seek an ophthalmological

tooth can be referred over the side of the face

opinion for their symptoms without relating

and cause some diagnostic confusion but it is

them to alcohol intake, perhaps urged on by an

usually worse when chewing or biting. Pain

anxious relative or friend. Chronic poisoning by

from a middle ear infection can cause similar

other drugs is too rare a cause of headache in

problems. The temporomandibular joint is a

ophthalmic practice to be considered here but it

recognised source of referred pain over the side

might have to be borne in mind.

of the face, and malfunctioning of the joint can

result from incorrect jaw alignment or poorly

Posttraumatic Headache

fitting dentures.

Nearly all patients who have suffered a

significant head injury complain of headaches.

Drugs

The pain can remain severe for many months

Overindulgence in alcohol is one of the three

and in the worst case can last a few years.

causes of morning headache; the other two

Usually, no obvious explanation can be found

being raised intracranial pressure and acute

apart from the original injury. The severity of

sinusitis. The diagnostic difficulty with alco-

the headache can sometimes appear to be

holism tends to be failure of the patient to admit

related to clinical depression following the

or recognise excessive drinking. It might seem

injury but other causes of headache, such as

strange that such a patient should ever seek a

ocular muscle imbalance or raised intracranial

doctor’s opinion about headache, but alcoholics

pressure, need to be excluded.

Contact Lenses

The widespread use of contact lenses means

soft contact lens was introduced. This had the

that the general practitioner and the ophthal-

great advantage of being soft and malleable and

mic casualty department find themselves con-

hence more comfortable to wear, but optically it

fronted with more and more patients who have

has never been quite as good as the rigid lens,

run into wearing problems of one kind or

especially when the patient has high degrees of

another. For this reason, some of the likely

astigmatism. Several different materials have

emergency requirements are considered here.

now been used in the production of soft lenses,

although the basic material used is hydroxy-

ethylmethacrylate. The different types of soft

Types of Contact Lens

lenses differ in their ability to take up water and

transmit oxygen.Lenses are now being made that

As long ago as 1912, a glass contact lens was

can be worn for long periods without needing to

being produced,but because of the manufactur-

be removed and cleaned. Similarly, disposable

ing difficulties and wearing problems, the wide-

and “planned-replacement” contact lenses are

spread use of this type of optical aid was delayed

now widely available. Care should be taken that

until the introduction of plastic scleral lenses in

such lenses are used under professional care.

1937. The obvious advantage of placing a lens

Soft contact lenses tend to absorb and adsorb

directly on the cornea over the wearing of spec-

material from the tear film. It is particularly

tacles is the cosmetic one, but the system also

important to ensure that a patient is not wearing

has optical advantages. Because the lens moves

a soft lens before fluorescein dye is instilled into

with the eye, there are none of the problems

the eye.

associated with looking through the edge of the

lens experienced by the wearer of spectacles. In

addition, a more subtle effect is the more accu-

Side Effects

rate representation of image size on the retina in

subjects with high degrees of refractive error.

In general, soft contact lenses have more side

Although the original type of moulded scleral

effects than rigid lenses in the long term. The

contact lenses are still occasionally used, they

commonest complication of wearing modern

have been largely replaced by the modern rigid

contact lenses is losing them. Patients are well

and soft lenses, which are much smaller and

advised to have a pair of glasses at hand in case

thinner and hence cause less interference with

they have contact-lens-wearing problems or a

corneal physiology. Rigid lenses are made

lens is lost. More serious trouble can result

from gas-permeable plastics and have generally

from clumsy handling of the lens or leaving a

replaced the early “hard” lenses, which were

rigid lens in the eye for too long a period. Such

impermeable to oxygen. In 1960, the hydrophilic

patients quite often present with severe pain in

Common Eye Diseases and their Management

the eye, and examination reveals a partially

Indications

healed corneal abrasion. This must be treated

in the usual manner and the patient advised

These can be considered as either cosmetic or

against wearing the lens again for several weeks,

therapeutic.

depending on the extent of the abrasion. The

contact lenses themselves should also be exam-

Cosmetic

ined by the patient’s fitter to make sure that they

are not faulty. Bearing in mind the troubles that

There are obvious cosmetic advantages for the

can ensue when an abrasion becomes recurrent,

wearer of contact lenses, especially the teenager.

the indications for wearing the lenses in the first

However, the potential wearer should realise the

place should be reconsidered.

possible difficulties involved: the need to clean

The risk of infection by lens contamination

and sterilise the lenses and the need for some

or secondary to corneal abrasions is increased.

degree of finger dexterity when they are

Recently, Acanthamoeba keratitis has been

inserted and removed. There are numerous and

described. This disease occurs more often in

varied cleaning and disinfection systems on the

contact lens wearers.

market. Contact lenses might be required for

Another sequel to wearing contact lenses,

certain pursuits, such as golf or athletics, where

either rigid or soft, is the appearance of chronic

the spectacle wearer is handicapped by misting

inflammatory changes in the conjunctiva, often

up of the glasses in wet weather. Patients over

characterised by a papillary conjunctivitis. The

the age of 45 or 50 will find that they require

resulting irritation and redness of the eyes can

reading glasses as well and these, of course, must

persist for some weeks after the wearing of

be worn over the contact lenses, thereby some-

the contact lenses ceases. Unfortunately, these

what reducing the cosmetic value of the latter.

symptoms can appear after wearing lenses suc-

Multifocal contact lenses are available but have

cessfully for some years and they tend to recur

limited success. Some patients tolerate being

in spite of renewing or modifying the lenses.

corrected in one eye for distance vision and in

Some patients who tolerate contact lenses well

the other for reading with contact lenses. Care

can develop corneal changes after some years.

should be taken in this situation when assessing

Peripheral vascularisation can become evident

the visual acuity because the eye corrected for

and in neglected cases, there could be band

near vision will be blurred for distance.

degeneration of the cornea. Some contact-lens

wearers complain of recurrent blurring of their

Therapeutic

vision and this could be due to an ill-fitting lens

producing corneal epithelial oedema or simply

There are instances when the contact lens can

to the excessive accumulation of mucus on the

result in much better vision than spectacles,

lens (Figure 10.1).

for example in patients with high degrees of

corneal astigmatism that are not fully cor-

rectable with glasses. This accounts for the

benefit of contact lenses in patients with kera-

toconus. Soft contact lenses are sometimes used

as “bandage lenses” to protect the cornea after

corneal burns or in patients with bullous kera-

topathy. The contact lens has a special impor-

tance in the correction of unilateral aphakia

(see Chapter 11) by reducing the image size on

the retina to such an extent that the two eyes can

once again be used together. If eye drops are

being regularly instilled into the eyes, soft

contact lenses can absorb the drug being used

or the preservative in the drops. In fact, attempts

have been made to use soft contact lenses as a

Figure

10.1. Hard contact lens with lipid deposits

(with

slow-release system by impregnating them with

acknowledgement to Professor M. Rubinstein).

the drug before fitting.

Cataract

“Cataract” means an opacity of the lens and it is

for this reason, tends to assume a spherical

the commonest potentially blinding condition

shape, or would do if the moulding of the lens

that confronts the eye surgeon. This is not to say

fibres allowed. In situ the shape of the lens is

that every person with cataract is liable to go

maintained by a series of taut fibres known as

blind. Many patients have relatively slight lens

the zonule. The fibres exert radial tension on the

opacities that progress slowly. Fortunately, the

lens but the tension is reduced when the circ-

results of surgery are good, a satisfactory im-

ular part of the ciliary muscle contracts. The

provement of vision being obtained in over 90%

reduced tension of the zonule allows the lens to

of cases. It is usually possible to forewarn the

assume a more spherical shape and hence the

patients when there is an extra element of doubt

anteroposterior diameter of the lens increases.

about the outcome. To the uninformed patient,

As a result, the refracting power of the lens

the word “cataract” strikes a note of fear and it

increases, that is to say, light rays are more bent

might be necessary to explain that opacities in

and the eye becomes focused on near objects.

the lens are extremely common in elderly

This process of accommodation, which is pro-

people. It is only when the opaque lens fibres

duced by relaxation of the lens but contraction

begin to interfere with the vision that the term

of the ciliary muscle, gradually becomes less

“cataract” is used. Many patients have a slight

effective as we grow older, probably because the

degree of cataract, which advances so slowly

lens becomes less malleable rather than because

that they die before any visual problems arise.

the ciliary muscle is becoming weaker. This

Nobody need now go blind from cataract;

reduction in the range of accommodation

however, one still encounters elderly people

explains why the little child will present an

who, from ignorance or neglect, are left immo-

object close to an adult’s eyes and expect him

bilised by this form of blindness, and it is esp-

or her to see it clearly. It also explains why, in

ecially important that the general practitioner is

the mid-40s, it becomes necessary to hold a

able to recognise the condition.

book further from one’s eyes if it is to be read

easily and also the subsequent inability to read

without the assistance of a spectacle lens, which

The Lens

provides additional converging power. The need

for reading glasses occurs in people with normal

The human lens is a surprising structure. It is

eyes at about the age of 45 (presbyopia) but this

avascular and yet it is actively growing through-

is only a milestone in a slowly progressive path

out life, albeit extremely slowly. It receives its

of deterioration that begins at birth.

nourishment from the aqueous fluid that bathes

Histological section of the lens reveals that

it. The lens is enclosed in an elastic capsule and,

beneath the capsule there is an anterior

Common Eye Diseases and their Management

epithelium with a single layer of cells, but no

Aetiology

such layer is evident beneath the posterior

capsule. Furthermore, if one follows the single-

Having learned of the complex structure of the

layered anterior epithelium to the equator of the

lens, perhaps one should be more surprised that

lens, the epithelial cells can be seen to elongate

the lens retains its transparency throughout life

progressively and lose their nuclei as they are

than that some of the lens fibres might become

traced into the interior of the lens. Thus, one can

opaque. There are a number of reasons why lens

deduce from histological sections that the lens

fibres become opaque but the commonest and

fibres are being continuously laid down from

most important is ageing. The various causes

the epithelial cells at the equator. The actual

will now be considered.

arrangement of the lens fibres is quite complex,

each fibre being made up of a prismatic six-

sided band bound to its fellow by an amorphous

Age

cement substance.

The majority of cataracts are associated with the

Slit-lamp examination of the lens reveals the

ageing process, and some of the biochemical

presence of the lens sutures, which mark the

changes in the lens fibres are now being under-

points of junction of the end of the lens fibres.

stood. We know that certain families are more

Two such sutures are usually seen, both often

susceptible to age-related cataract, but a degree

taking the form of the letter “Y”, the posterior

of opacification of the lens is commonplace in

suture being inverted. The lens fibres contain

the elderly. Often the opacity is limited to the

proteins known as “crystallins” and have the

peripheral part of the lens and the patient might

property of setting up an antigen-antibody

be unaware of any problem. It is usual to limit

reaction if they are released into the eye from

the term “cataract” to the situation where the

the lens capsule. One other feature of the lens,

opacities are causing some degree of visual

which can usually be seen with the slit-lamp

impairment. Elderly patients are often reas-

microscope, is an object looking like a pig’s tail,

sured to learn that their eye condition is part of

which hangs from the posterior capsule. This is

the general ageing process and that only in

the remains of the hyaloid artery, a vessel that

certain instances does the opacification pro-

runs in the embryonic eye from the optic disc to

gress to the point where surgery is required.

the vascular tunic of the lens, which is present

at that stage (Figure 11.1).

Diabetes

The new junior doctor working in an eye hos-

pital must be impressed by the number of dia-

betics with cataracts who pass through his or

her hands, and might be forgiven for deducing

that diabetes is a common cause of cataract. To

see the situation in perspective, one must realise

that both cataracts and diabetes are common

diseases of the elderly and coincide quite often.

Of course, the matter has been investigated from

the statistical point of view and it has been

shown that there is a somewhat higher incid-

ence of cataract in diabetics, mainly because

they tend to develop lens opacities at an earlier

age. A special type of cataract is seen in young

diabetics and in these cases, the lens can become

rapidly opaque in a few months. Fortunately,

this is not common, usually occurring in

Figure 11.1. Cross-section of a child’s lens: aqueous on left, vit-

insulin-dependent (type 1) patients who have

reous on right. Note the hyaloid remnant and the “Y” sutures

had difficulty with the control of their diabetes.

(with acknowledgement to M. L. Berliner, 1949).

It is claimed that, in its early stages, this type of

Cataract

cataract can be reversible, but such an occur-

occasionally medicolegal claims are made for

rence is so rare that it has not presented much

compensation when a cataract has developed

opportunity for study.

following a blow on the side of the head.

Secondary Causes

Perforation

Cataract can be secondary to disease in the eye

A perforating wound of the eye bears a much

or disease elsewhere in the body.

higher risk of cataract formation. If the perf-

orating object (e.g., a broken beer glass) passes

through the cornea without touching the lens,

Secondary to Disease in the Eye

the lens is usually spared and, in the absence

More or less any terminal event in the eye tends

of significant contusion, a cataract does not

to be associated with cataract. Advanced uncon-

form. This, of course, also depends on careful

trolled glaucoma is often associated with an

management of the corneal wound and the

opaque lens, as are chronic iridocyclitis and

prevention of infection. Unfortunately, such

intraocular tumours. Certain specific eye dis-

perforating injuries can also involve splitting of

eases are accompanied by cataract; for example,

the lens capsule, with spilling out of the lens

patients who suffer from the inherited retinal

fibres into the anterior chamber. The series of

degeneration, retinitis pigmentosa, sometimes

events following such an injury is dependent on

develop a particular type of opacity in the pos-

the age of the individual. When the lens capsule

terior part of the lens. The removal of such a

of a child is ruptured, a vigorous inflammatory

cataract can sometimes restore a considerable

reaction is set up in the anterior chamber and

amount of vision, at least for a time.

the lens matter will usually gradually become

absorbed, in the absence of treatment, over a

period of about a month. This leaves behind the

Secondary to Disease Elsewhere

lens capsule and often a clear pupil. In spite of

It might be recalled that the lens is ectodermal,

this, the patient cannot see clearly because most

being developed as an invagination of the over-

of the refractive power of the eye is lost. This has

lying surface ectoderm. It is not surprising,

serious optical consequences and the need for

therefore, that some skin diseases are associated

an artificial intraocular lens. When the lens

with cataract. In particular, patients suffering

capsule of an adult is ruptured, a similar

from asthma and eczema might present to the

inflammatory reaction ensues, but there tends

eye surgeon in their late

50s. Dysfunction

to be more fibrosis, and a white plaque of fibrous

of the parathyroid glands is a rare cause of

tissue could remain to obstruct the pupil.

cataract and Down’s syndrome is a more

Rarely, it is possible for a lens to be perforated

common association.

with subsequent opacity limited to the site of

perforation - indeed, one occasionally sees a

foreign body within the lens surrounded by

Trauma

opaque fibres but limited to a small part of

the lens.

Contusion

A direct blow on the eye, if it is severe enough,

Radiation

can cause the lens to become opaque. An injury

from a squash ball is a typical example of the

Visible light does not seem to cause cataract,

type of force required. Sometimes the appear-

although claims have been made that indiv-

ance of the cataract might be delayed even for

iduals from white races living for long periods

several years. The onset of unilateral cataract

in the tropics can show a higher incidence of

must always make one suspect the possibility of

cataract. In practice, this is not easy to confirm.

previous injury, but a cause-and-effect relation-

In spite of public misapprehension, ultraviolet

ship can be difficult to prove in the absence of

light probably does not cause cataract either,

any other signs of previous contusion. It seems

because the shorter wavelengths fail to pene-

unlikely that a cataract would form unless there

trate the globe. These shorter wavelengths

had been a direct blow on the eye itself, although

beyond the blue end of the visible spectrum can

Common Eye Diseases and their Management

produce a dramatic superficial burn of the

Symptoms

cornea, which usually heals in about 48 h. This

injury, which is typified by “snow blindness” and

“welders’ flash”, will be discussed in Chapter 15.

Many patients complain of blurred vision,

Prolonged doses of infrared rays can produce

which is usually worse when viewing distant

cataract; this used to be seen occasionally in

objects. If the patient is unable to read small

glassblowers and steel workers, but the wearing

print, the surgeon might suspect that other

of goggles has now more or less eliminated

pathology, such as macular degeneration, could

this. X-rays and gamma rays can also produce

be present. One must bear in mind that some

cataracts, as was witnessed by the mass of

elderly patients say that they cannot read when

reports that followed the explosion of the

it is found that they can read small print if care-

atomic bombs at Nagasaki and Hiroshima in

fully tested. It is a curious fact that when the

Japan. Radiation cataract is now seen following

cataract is unilateral, the patient can claim that

whole-body radiation for leukaemia but the risk

the loss of vision has been quite sudden. Elu-

is only significant when therapeutic doses of

cidation of the history in these cases sometimes

X-rays are used.

reveals that the visual loss was noted when

washing and observing the face in the mirror.

When one hand is lowered before the other, the

Congenital Factors

unilateral visual loss is noticed for the first time

Many of the cases of congenital cataract seen in

and interpreted as a sudden event. The history

ophthalmic practice are inherited. Sometimes

in cataract cases might be further confused by a

there is a dominant family history and there are

natural tendency for patients to project their

many other possible associated defects, some

symptoms into the spectacles, and several pairs

of which fit into named syndromes. Acquired

might be obtained before the true cause of the

congenital cataract can result from maternal

problem is found. In order to understand the

rubella infection during the first trimester of

symptoms of cataract, it is essential to under-

pregnancy. The association of deafness, con-

stand what is meant by index myopia. This

genital heart lesions and cataract must always be

simply refers to the change in refractive power

borne in mind. The ophthalmic house surgeon

of the lens, which occurs as a preliminary to

must take special care when examining the con-

cataract formation. Index myopia can also

genital cataract case preoperatively and likewise,

result from uncontrolled diabetes. If we imagine

the paediatric house surgeon must bear in mind

an elderly patient who requires reading glasses

that congenital cataracts might be overlooked,

(for presbyopia) in the normal way but no

especially if they are not severe. Sometimes the

glasses for viewing distant objects, the onset of

cataracts can be slight at birth and gradually

index myopia will produce blurring of distance

progress subsequently, or sometimes they can

vision, but also the patient will discover to his

remain stationary until later years.

or her surprise that it is possible to read again

without glasses. In the same way, the hyper-

metropic patient will become less hyper-

Toxicity

metropic and find that it is possible to see again

Toxic cataracts are probably rare, although

in the distance without glasses. The ageing

several currently used drugs have been incrim-

fibres in the precataractous lens become more

inated, the most notable being systemic steroids.

effective at converging light rays so that parallel

Chlorpromazine has also been shown to cause

rays of light are brought to a focus more anteri-

lens opacities in large doses, and so has the use

orly in the eye.

of certain meiotics, including pilocarpine. Much

Apart from blurring of vision, the cataract

of our knowledge of drug-induced cataracts

patient often complains of monocular diplopia.

is based on former animal experiments. The

Sometimes even a slight and subtle opacity in

potential danger of new drugs causing cataract

the posterior part of the lens can cause the

was shown in the 1930s after the introduction of

patient to notice, for example, that car rear lights

dinitrophenol as a slimming agent. This pro-

appear doubled, and this can be reproduced

duced a large number of lens opacities before it

with the ophthalmoscope light. Monocular

was eventually withdrawn.

diplopia is sometimes regarded as a rather

Cataract

suspect symptom, the suggestion being that if a

Snellen test type depends as much on the pos-

patient continues to see double, even when one

ition of the opacities in the lens as on the

eye is closed, then he or she might not be giving

density of the opacities.

an accurate history. In actual practice nothing

could be further from the truth and this is quite

Findings of Ophthalmoscopy

a common presenting feature of cataract.

Glare is another common presenting symp-

The best way of picking up a cataract in its early

tom. The patient complains that he or she

stages is to view the pupil through the ophthal-

cannot see so well in bright light and might even

moscope from a distance of about 50 cm. In this

be wearing a pair of dark glasses. Glare is a

way, the red reflex is clearly seen. The red reflex

photographic term but here it refers to a

is simply the reflection of light from the fundus

significant reduction in visual acuity when an

and it is viewed in exactly the same manner that

extraneous light source is introduced. Light

one might view a cat’s eyes in the headlamps of

shining from the side is scattered in the catarac-

one’s car or the eyes of one’s friends in an ill-

tous lens and reduces the quality of the image

judged flash photograph. In fact, such a flash

on the retina. Glare becomes an important con-

photo could well show up an early cataract if an

sideration when advising an elderly cataractous

elderly relative were included in the photo-

patient on fitness to drive. The visual acuity

graph. When using the ophthalmoscope, the

might be within the requirements laid down

opacities in the lens are often seen as black

by law (seeing a number plate at 20.5 m) but

spokes against the red reflex (Figure 11.2). It is

only when the patient is tested in the absence

important to focus one’s eyes onto the plane of

of glare.

the patient’s pupil if the cataract is to be well

A consideration of all these factors makes it

seen, and it is preferable to dilate the pupil

relatively easy to diagnose cataract even before

beforehand or at least examine in a darkened

examining the patient. To summarise, a typical

room. Typical age-related lens opacities are

patient might complain that the glasses have

wedge shaped, pointing towards the centre of

been inaccurately prescribed, that the vision is

the pupil. At the same time, the central nucleus

much worse in bright sunlight, that sometimes

of the lens can take on a yellowish-brown

things look double and that there is difficulty in

colour, the appearance being termed

“lens

recognising people’s faces in the street rather

sclerosis”, and ultimately, the lens can become

than difficulty in reading. Patients with

nearly black in some instances.

cataracts alone do not usually complain that

After inspecting a cataract with the ophthal-

things look distorted or that straight lines look

moscope held at a distance from the eye, one

bent, nor do they experience pain in the eye.

must then approach closer and attempt to

Rarely, cataracts become hypermature; that is

examine the fundus. Further useful infor-

to say, the lens enlarges in the eye and this in

mation about the density of the cataract can be

turn can lead to secondary glaucoma and pain

obtained in this way. It is generally true that if

in the eye. Urgent surgery might be needed

under these circumstances. In its late stages, a

cataract matures and becomes white, so that

exceptionally a patient might complain of a

white spot in the middle of the pupil.

Signs

Reduced Visual Acuity

A reduction in visual acuity can, of course, be

an early sign of cataract formation but this is

not always the case. Some patients see surpris-

ingly well through marked lens opacities, and

Figure 11.2. Opaque areas in the lens can be seen clearly

the effect on visual acuity as measured by the

against the red reflex.

Common Eye Diseases and their Management

the observer can see in, the patient can see out.

likelihood of restoring good vision to a blind

If there is an obvious discrepancy between the

eye. The function of the peripheral retina can be

clarity of the fundus and the visual acuity of

usefully assessed by performing the light pro-

the patient, some other pathology might be sus-

jection test. This entails seating the patient in a

pected. Sometimes the patient might not have

darkened room, covering one eye, and asking

performed too well on subjective testing and

him or her to indicate, by pointing, the source of

such an error should be apparent when the

light from a torch positioned at different points

fundus is viewed. Some types of cataract can be

in the peripheral field. Checking the pupil and

misleading in this respect and this applies par-

the light projection test take a brief moment to

ticularly to those seen in highly myopic patients.

perform and are by far the most important

Here, there is sometimes a preponderance of

tests of retinal function when the retina can-

nuclear sclerosis, which simply causes distor-

not be seen directly. A number of other more

tion of the fundus while the disc and macula

sophisticated tests are available, for exam-

can be seen quite clearly.

ple ultrasonography, electroretinography and

measurement of the visually evoked potential.

Sometimes, at least an area of the peripheral

Findings on Slit-lamp Microscopy

retina can be seen when the pupils have been

A detailed view of any cataract can be obtained

dilated, and all cataract patients should be

with the slit-lamp. By adjusting the angle and

examined in this way before one embarks on

size of the slit beam, various optical sections of

more complex tests. A search for the signs of

the lens can be examined, revealing the exact

cataract thus involves a full routine eye exami-

morphology of the cataract. The presence of

nation, including a measurement of the best

small vesicles under the anterior lens capsule

spectacle correction.

can be seen as an early sign of senile cataract.

Cataracts secondary to uveitis or to drugs might

first appear as an opacity in the posterior sub-

Management

capsular region. For optical reasons, an opacity

in this region tends to interfere with reading

At the present time, there is no effective medical

vision at an early stage. Opacities in the lens

treatment for cataract in spite of a number of

can appear in a wide range of curious shapes

claims over the years. A recent report has sug-

and sizes, and earlier in the last century there

gested that oral aspirin can delay the progress of

was a vogue for classifying them with Latin

cataract in female diabetics. Although this

names, which are now largely forgotten. Such a

might be expected to have some effect on

classification is of some help in deciding the

theoretical grounds, any benefit is probably

cause of the cataract, although it can sometimes

marginal. Occasionally, patients claim that their

be misleading. Congenital cataracts are usually

cataracts seem to have cleared, but such fluc-

quite easily identified by their morphology, as

tuation in density of the lens opacities has not

are some traumatic cataracts. When a unilateral

been demonstrated in a scientific manner.

cataract appears many years after a mild contu-

Cataracts associated with galactosaemia are

sion injury, it can be difficult to distinguish this

thought to clear under the influence of prompt

from an age-related one.

treatment of the underlying problem.

Cataract is, therefore, essentially a surgical

problem, and the management of a patient with

Other Important Signs

cataract depends on deciding at what point

Certain other important signs need to be care-

the visual impairment of the patient justifies

fully elicited in a patient with cataracts. The

undergoing the risks of surgery. The cataract

pupil reaction is a particularly useful index of

operation itself has been practiced since

retinal function and it is not impaired by the

pre-Christian times, and developments in recent

densest of cataracts. A poor reaction might lead

years have made it safe and effective in a large

one to suspect age-related macular degeneration

proportion of cases. The operation entails

or chronic glaucoma, but a brisk pupil with a

removal of all the opaque lens fibres from

mature cataract might be described as a

within the lens capsule and replacing them with

“surgeon’s delight” because it indicates the

a clear plastic lens.

Cataract

In the early part of the last century the tech-

a visual acuity of 6/9, whereas others with less

nical side of cataract surgery necessitated

visual demands might be quite happy with a

waiting for the cataract to become “ripe”. Nowa-

vision of 6/12 or 6/18. Early surgery might be

days no such waiting is needed and it is

needed to keep a joiner or bus driver at work for

theoretically possible to remove a clear lens. The

which good binocular vision is needed.

decision to operate is based on whether the

patient will see better afterwards. Modern

Age of the Patient

cataract surgery can restore the vision in a

remarkable way and patients often say that they

By itself, the age of the patient need have little

have not seen so well for many years. Indeed,

influence on the decision to operate. Many

many patients have quite reasonable vision

people over the age of 100 years have had their

without glasses but this cannot be guaranteed

cataracts successfully removed. The general

and, because the plastic lens implant gives a

health of the patient must be taken into account

fixed focus, glasses will inevitably be needed for

and this can influence one’s decision in unex-

some distances. Probably the worst thing that

pected ways. Occasionally, one is presented with

can happen after the operation is infection

a patient who has difficulty with balancing,

leading to endophthalmitis and loss of the sight

perhaps as a result of Ménière’s disease or some

of the eye. Although this only occurs in about

other cause. The patient asks for cataract

one out of a thousand cases, the patient con-

surgery in the hope that this will cure the

templating cataract surgery needs to be aware of

problem. Unless the cataracts are advanced,

the possibility. Before the operation, it is now a

the result might be disappointing. Sometimes

routine to measure the length of the eye and the

cataract surgery is requested in a nearly blind,

corneal curvature. Knowing these two measure-

demented patient on the grounds that the

ments, one can assess the strength of lens

dementia will improve with improvement of the

implant that is needed. When deciding on the

vision. Although this occasionally happens,

strength of implant, it is necessary to consider

often the patient’s mental state is made worse

the other eye. The aim is usually to make the two

even though the sight is better. This raises some

eyes optically similar because patients find it

interesting ethical problems for the surgeon

difficult to tolerate two different eyes.

and relatives.

In the case of the child with congenital

cataracts, the indications for surgery depend

When to Operate

largely on the degree of opacification of the lens.

Even though the decision to operate on a

An incomplete cataract might permit a visual

cataract must be made by the ophthalmic

acuity of 6/12 or 6/18 and yet the child could be

surgeon, optometrists and the nonspecialist

able to read small print by exercising the large

general practitioner need to understand the rea-

amount of available focusing power. Such a

soning behind this decision. Elderly patients

child could undergo normal schooling, and

tend to forget what they have been told in the

cataract surgery might never be required. A

clinic and might not, for example, understand

complete cataract in both eyes demands early

why cataract surgery is being delayed when

surgery and this can be undertaken during the

macular degeneration is the main cause of visual

first few months of life. There is a high risk that

loss. An operation is usually not required if the

one eye could become amblyopic in these young

patient has not noticed any problem, although

patients, even after cataract surgery.

sometimes the patient can deny the problem

through some unexpressed fear. The require-

Traumatic Cataract

ments of the patient need to be considered;those

of the chairbound arthritic 80-year-old subject

This is usually a unilateral problem in a younger

who can still read small print quite easily are dif-

patient and sometimes the nature of the damage

ferent from the younger business person who

to the eye prevents the insertion of an intra-

needs to be able to see a car number plate at

ocular lens. The patient could be left with no

20.5 m in order to drive. The visual acuity by

lens in the eye, a situation known as aphakia.

itself is not always a reliable guide. Some patients

Vision can be restored by a strong convex

who have marked glare might need surgery with

spectacle lens but the difference between the

Common Eye Diseases and their Management

two eyes makes it impossible to wear glasses.

This is partly because everything looks much

bigger with the corrected aphakic eye; the image

on the retina is abnormally large. By wearing a

contact lens on the cornea, the optical problems

might be solved, but it is an unfortunate fact that

patients with traumatic cataracts usually have

working conditions that are unsuited to the

wearing of a contact lens.

The Cataract Operation

Every medical student should witness at least

one cataract operation during the period of

Figure 11.3. A typical plastic intraocular implant.There are dif-

training. It is an example of a classical pro-

ferent designs to suit different surgical techniques.

cedure, which has been practiced for 3000 years.

The earliest method for dealing with cataract

was known as couching. This entailed pushing

the lens back into the vitreous, where it was

complete lens within its capsule and, by this

allowed to sink back into the fundus of the eye.

means, avoided subsequent operations to open

Although this undoubtedly proved a simple and

up residual opaque posterior capsule.

satisfactory procedure in some instances, there

Perhaps the most dramatic change in cataract

was a tendency for the lens to set up a vigorous

surgery has occurred in the latter half of the

inflammatory reaction within the eye, with sub-

twentieth century, with the introduction of

sequent loss of sight.

intraocular acrylic lens implants. Initially, they

Modern cataract surgery was founded by the

were mostly employed with intracapsular

French surgeon Jacques Daviel in the eighteenth

surgery, but a new technique for extracapsular

century. The operation that he devised involved

surgery was then developed and found to be

seating the patient in a chair and making an

successful with implants. Many different types

incision around the lower half of the cornea.

and designs of intraocular lens have been used

The lens was then removed through the

over the years. Figure 11.3 shows a commonly

opening. The results claimed were remarkable

used type of lens implant. The trend is now

considering the technical difficulties that he

towards smaller incision surgery and the use of

must have encountered. Subsequently, the pro-

foldable or injectable implants, which unfold

cedure was facilitated by lying the patient down

into position as they are being inserted into the

and making the incision around the upper part

eye. An important and widely used technique is

of the cornea where, in the postoperative

phakoemulsification. Here, the opaque lens

period, it was protected by the upper eyelid. The

nucleus is removed through a complex cannula,

use of local anaesthesia was introduced at the

which breaks up the lens matter ultrasonically

end of the nineteenth century and at the same

before sucking it from the eye (Figures 11.4, 11.5

time, attempts were made to suture the cornea

and 11.6).

back into position. By the beginning of the

twentieth century, two methods had evolved for

the actual removal of the lens. The safest way

was to incise the anterior lens capsule and then

wash out or express the opaque nucleus, pre-

serving the posterior lens capsule as a protec-

tive wall against the bulging vitreous face. This

is known as the extracapsular technique. The

intracapsular cataract extraction became the

standard operation of choice in most patients

over the age of 50 years during the early part of

Figure 11.4. Type of probe used for phakoextraction of the

the twentieth century. It involved removing the

opaque lens nucleus.

Cataract

case work, dictated partly by economic reasons,

but also by safer surgery.

Convalescence

It is a fair generalisation to say that an eye

requires about four to six weeks for full healing

to take place following a cataract operation. On

the other hand, most of the healing takes place

in the first two weeks. It is usual for patients to

return to work after two weeks. After phakoe-

mulsification, glasses can be prescribed at this

point but after larger incision surgery the pre-

scription of new glasses is usually done after a

month. The visual recovery is undoubtedly

quicker after small incision surgery but the ulti-

mate visual result is probably no better than

when a larger incision is used. Most hospitals

provide a “hand-out” of do’s and don’ts for the

Figure. 11.5. Injection of intraocular lens implant through

patients. The important thing is for the patient

small incision.

to avoid rubbing the eye and to seek immediate

medical advice if the eye becomes painful,

because this can indicate infection, which

Time Spent in Hospital

requires immediate treatment to prevent blind-

ness. Following routine cataract surgery, it is

Many cataract operations are now done under

usual to instill antibiotic drops combined with a

local anaesthesia as day cases. General anaes-

steroid (usually in one bottle) four times daily

thesia is preferred in younger patients and esp-

for three to four weeks.

ecially where there is a risk of straining or

Infection is the rare but dreaded complication

moving during the procedure as, for example,

and this is usually heralded by pain, redness,

when the patient is deaf. An overnight stay is

discharge and deterioration of vision. The infec-

needed after a general anaesthetic in many

tion might be acquired from the patient’s own

cases. The elderly patient living alone with no

commensal eyelid flora or from contamination

relatives is also usually kept overnight in hospi-

at the time of surgery. The commonest types of

tal but the trend is towards more and more day-

bacterial infection are streptococcal and staphy-

lococcal species. About

10-20% of patients

develop opacification of the posterior lens

capsule behind the implant after months or

years. This is simply cured by making an

opening in the capsule with a special type of

laser. This is a day-case procedure, which

requires no anaesthetic and takes two or three

minutes. When corneal sutures have been used,

these can sometimes need to be removed and

this can also be done on a “while-you-wait” basis

in the outpatient department.

Summary

At primary care level, it is important to be able

to diagnose cataract but also to understand the

benefits and risks of cataract surgery in order to

Figure 11.6. Intraocular lens implant within capsular bag.

Common Eye Diseases and their Management

be able to give the patient advice as to when the

cataract is bad enough to need an operation. An

understanding of the meaning of aphakia and

the optical consequences of an implant are also

useful. Most patients who present with cataracts

are diagnosed as having age-related cataracts

and investigations as to the cause are limited to

tests to exclude diabetes and to confirm that the

patient is fit for surgery. An understanding of

the symptoms of cataract is helped by under-

standing the meaning of index myopia.

Figure 11.7 is a final reminder of the signs

and symptoms of cataract. An elderly woman

would not normally be able to read small

print without glasses and this lady’s eyes

must be abnormal. She might have inherited

myopia, allowing her to see near objects without

the need for a presbyopic lens, but the myopia

could also be index myopia, which in turn

could be caused by early cataract formation.

Another cause of index myopia could be

uncontrolled diabetes.

Figure 11.7. An elderly person cannot read without glasses

unless he or she is myopic. Myopia in the elderly can be caused

by cataract. (“Rembrandt’s mother”, with acknowledgement to

Rijksmuseum-Stichting.)

Glaucoma

The word “glaucoma” refers to the apparent

Maintenance of

grey-green colour of the eye suffering from an

attack of acute narrow-angle glaucoma. Now-

Intraocular Pressure

adays the term has come to cover a group of eye

diseases characterised by raised intraocular

If the eye is to function as an effective optical

pressure. These diseases are quite distinct and

instrument, it is clear that the intraocular pres-

the treatment in each case is quite different.

sure must be maintained at a constant level. At

Glaucoma might be defined as a “pathological

the same time, an active circulation of fluid

rise in the intraocular pressure sufficient

through the globe is essential if the structures

enough to damage vision”. This is to distinguish

within it are to receive adequate nourishment.

the normal elevation of intraocular pressure

The cornea and sclera form a tough fibrous and

seen in otherwise normal individuals. Here, we

unyielding envelope and within this an even

consider what is meant by the “normal intra-

pressure is maintained by a balance between the

ocular pressure”.

production and drainage of aqueous fluid.

Aqueous is produced by the ciliary epi-

thelium by active secretion and ultrafiltration. A

Normal Intraocular Pressure

continuous flow is maintained through the

pupil, where it reaches the angle of the anterior

Measurement of the intraocular pressure in a

chamber.

large number of normal subjects reveals a

On reaching the angle of the anterior

normal distribution extending from pressures

chamber, aqueous passes through a grill known

of 10-12 mmHg to 25-28 mmHg. The pattern of

as the trabecular meshwork and then reaches a

distribution fits a Gaussian curve, so that the

circular canal embedded in the sclera known as

majority of subjects have a pressure of about

Schlemm’s canal. This canal runs as a ring

16 mmHg. For clinical purposes, it is necessary

around the limbus (corneoscleral junction) and

to set an arbitrary upper limit of normal. By

from it, minute channels radiate outwards

and large, the eye can stand low pressures

through the sclera to reach the episcleral circ-

remarkably well, but when the pressure is

ulation. These channels are known as aqueous

abnormally high, the circulation of blood

veins and they transmit clear aqueous to the

through the eye becomes jeopardised and

episcleral veins, which lie in the connective

serious damage can ensue. For clinical pur-

tissue underlying the conjunctiva. In actual fact,

poses, an upper level of

21 mmHg is often

the proof of the route of drainage of aqueous

accepted. Above this level, suspicions are raised

can be verified by any medical student - it

and further investigations undertaken.

simply entails examining the white of the eye

Common Eye Diseases and their Management

around the cornea with extreme care, using the

measurement of the intraocular pressure is such

high power of the slit-lamp microscope. After a

a basic requirement in any eye clinic, attempts

time, one can sometimes detect that some of the

have been made to introduce even more rapid

deeper veins convey parallel halves of blood and

and efficient devices. Perhaps the most ingen-

aqueous in the region beyond the junction of

ious to date is the tonometer, which measures

aqueous and episcleral vein.

the indentation of the cornea in response to a

The relative parts played by ciliary epithelium

puff of air by a photoelectric method. This air-

and trabecular meshwork in maintaining what

puff tonometer is less accurate than applan-

is a remarkably constant intraocular pressure

ation, but it is useful for screening, although

throughout life are not fully understood. It

abnormal results should be confirmed by

would appear that the production of aqueous is

Goldmann tonometry.

an active secretion, whereas the drainage is

more passive, although changing the tone of the

ciliary muscle can alter the rate of drainage. In

Clinical Types of Glaucoma

normal subjects, the intraocular pressure does

not differ in the two eyes by more than about

It has been mentioned above that the word

3 mmHg. Wider differences can lead one to

“glaucoma” refers to a group of diseases. For

suspect early glaucoma, especially if there is a

clinical purposes, these can be subdivided into

family history of the disease. The normal

five types:

intraocular pressure undergoes a diurnal varia-

1. Primary open-angle glaucoma.

tion, being highest in the early morning and

gradually falling during the first half of the day.

2. Normal pressure glaucoma.

This diurnal change could become exaggerated

3. Acute angle-closure glaucoma.

as the first sign of glaucoma.

4. Secondary glaucoma.

5. Congenital glaucoma.

Measurement of

Primary Open-angle Glaucoma

Intraocular Pressure

The first important point to note about this

The gold-standard method of intraocular pres-

disease is that it is common, occurring in about

sure measurement is Goldmann applanation

1% of the population over the age of 50 years.

tonometry. The Goldmann tonometer is sup-

The second point is that the disease is inherited,

plied as an accessory to the slit-lamp micro-

and whereas the practice of screening the whole

scope. The principle of applanation is as follows:

population for the disease is problematic in

when two balloons are pushed together so that

terms of finance, it is well worth screening the

the interface is a flat surface, the pressure within

families of patients with the disease if those over

the two balloons must be equal. By the same

the age of 40 years are selected. This leads to the

argument, when a fixed flat surface is pressed

third point, which is that the incidence increases

against a spherical surface, such as the cornea,

with age, being rare under the age of 40 years.

at the point at which the spherical surface is

This insidious, potentially blinding disease

exactly flattened, the intraocular pressure is

affects those who are least likely to notice its

equal to the pressure being applied. The app-

onset, and elderly patients with advanced

lanation head is a small Perspex rod with a

chronic open-angle glaucoma are still seen from

flattened end, which is fitted to a moveable arm.

time to time in eye clinics.

The tension applied to the moveable arm can be

Primary open-angle glaucoma occurs more

measured directly from a dial on the side of the

commonly in high myopes and diabetics;

instrument. The observer looks through the rod

patients with Fuchs’ corneal endothelial dystro-

using the microscope of the slit-lamp, and the

phy and retinitis pigmentosa also have a higher

point at which exact flattening occurs can thus

incidence. Glaucoma is commoner in different

be gauged. For applanation tonometry, the

racial groups. For example, individuals of

patient is seated at the slit-lamp and not lying

African descent, especially those from West

down but it is still necessary to instill a drop of

Africa and the Caribbean, carry a significantly

local anaesthetic beforehand. Because the

greater risk of glaucoma.

Glaucoma

Pathogenesis and Natural History

The intraocular pressure creeps up gradually

to 30-35 mmHg, and it is this gradual rise that

Histologically, there are remarkably few changes

accounts for the lack of symptoms. Such a rise

to account for the raised intraocular pressure,

in intraocular pressure impairs the circulation

at least in the early stages of the disease.

of the optic disc, and the nerve fibres in this

Subsequently, degenerative changes have been

region become ischaemic. The combined effect

described in the juxtacanalicular trabecular

of raised intraocular pressure and atrophy

meshwork, with endothelial thickening and

of nerve fibres results in gradual excavation of

oedema in the lining of Schlemm’s canal. It has

the physiological cup, and it is extremely useful

been shown that in the majority of cases the

to be able to identify this effect of raised

problem is one of inadequate drainage rather

intraocular pressure at an early stage. Figure

than excessive secretion of aqueous. In the

12.1 shows an optic disc undergoing various

untreated patient, the chronically raised pres-

stages of pathological cupping. In the first

sure leads to progressive damage to the eye and

instance, the central physiological cup becomes

eventual blindness. The rate of progress of the

enlarged, with its long axis arranged vertically.

disease varies greatly from individual to indiv-

Notching of the neuroretinal rim of the optic

idual. It is possible for gross visual loss to occur

disc tissue, especially in the inferotemporal and

within months, but the process may take five

superotemporal region, is common. The edge of

years. Younger eyes survive a raised pressure

the optic disc cup corresponds to the bend in

rather better than older eyes, which could

the blood vessels as they cross the disc surface.

already have circulatory problems. Few eyes can

In some eyes the area of pallor can correspond

withstand a pressure of 50 mmHg for more than

to the cup, while in others the cup is larger than

a week or two or a pressure of 35 mmHg for

more than a few months.

Primary open-angle glaucoma is nearly

always bilateral, but often the disease begins in

one eye, the other eye not becoming involved

immediately. It is important to realise that the

progress of chronic glaucoma can be arrested by

treatment, but unfortunately, many ophthalmol-

ogists experience the natural history of the

disease by seeing neglected cases.

Symptoms

Most patients with chronic glaucoma have

no symptoms. That is to say, the disease is

insidious and is only detected at a routine eye

examination, either by an optometrist or

ophthalmologist, before the patient notices

any visual loss. Occasionally, younger patients

notice a defect in their visual field but this is

unusual. Unfortunately, the peripheral loss of

visual field can pass unnoticed until it has

reached an advanced stage.

Signs

The three cardinal signs are:

1. Raised intraocular pressure.

2. Cupping of the optic disc.

3. Visual field loss.

Figure 12.1. The effect of glaucoma on the optic disc.

Common Eye Diseases and their Management

the area of pallor. It is particularly useful to

observe the way in which the vessels enter and

leave the nerve head (Figure 12.2). A flame-

shaped haemorrhage at the disc margin can be

seen. Localised loss of retinal nerve fibres can

be observed, especially with a red-free light.

Diagnostic instrumentation, such as the GDx

nerve fibre layer analyser, is capable of measur-

ing the thickness of the retinal nerve fibre layer

in microns, and offers an adjunctive objective

measure for diagnosing and monitoring

Figure 12.3. GDx nerve fibre scan result.

glaucoma (Figure 12.3).

The changes in the visual field can be

deduced from observing the disc and from con-

the optic nerve head in the right eye. The blind

sidering the arrangement of the nerve fibres in

spot is rounded and about 8-12° lateral to and

the eye. If we gaze fixedly with one eye at a spot

slightly below the level of fixation. It has already

on the wall and then move a small piece of paper

been mentioned that the glaucomatous disc is

on the end of a paper clip, or even the end of our

initially excavated above and below so that the

index finger, in such a manner as to explore our

patient with early glaucoma has a blank area in

peripheral field, it is soon possible to locate the

the visual field extending in an arcuate manner

blind spot. In the case of the right eye, this is

from the blind spot above and below fixation.

found slightly to the right of the point of fixation

This typical pattern of field loss is known as the

because it represents the projected position of

arcuate scotoma (Figure 12.4). If the glaucoma

remains uncontrolled, this scotoma extends

peripherally and centrally. It can be seen that

even at this stage the central part of the field

could be well preserved and the patient can still

be able to read the smallest letters on the Snellen

test chart. If the field loss is allowed to progress

further, the patient becomes blind.

Figure 12.2. a Glaucomatous cupping of the disc early cupping;

b advanced cupping.

Figure 12.4. Superior arcuate visual field defect, right eye.

Glaucoma

Treatment

genuinely anxious to preserve their eyesight.

Compliance with glaucoma medication is a

For many years, the mainstay of treatment for

major problem when medications are taken

primary open-angle glaucoma has been the use

more than once daily, and is a relatively

of miotic drops. The miotic of choice was

common reason for disease progression.

pilocarpine, starting with a 1% solution and

Timolol and other beta-blockers are effective

increasing to 4% if needed. Subsequently, beta-

over a 12-h period and need to be instilled only

blockers, for example, timolol, levubunolol

twice daily. As an ocular hypotensive agent,

(Betagan) and betaxolol

(Betoptic) replaced

these are probably not quite as effective as pilo-

pilocarpine, and now prostaglandin analogues,

carpine, but many cases of chronic glaucoma are

for example, latanoprost (Xalatan) have largely

now satisfactorily controlled by them and

replaced beta-blockers as first-line medications

furthermore, the drug may be used in combin-

(Table 12.1). In practice, these medications are

ation with pilocarpine. Beta-blockers have the

often used in combination.

further advantage that they do not cause any

Pilocarpine itself is effective in reducing

miosis. The main side effects of beta-blockers

intraocular pressure. After about half an hour

are bronchospasm, reduced cardiac contrac-

from the moment of instillation, the pupil

tility and bradycardia. They are, therefore,

becomes small and the patient experiences

contraindicated in patients with chronic obs-

dimming of the vision, aching over the eyebrow

tructive airway disease, heart block, hypo-

and a spasm of accommodation, which blurs the

tension and bradycardia.

distance vision. At the same time, the intra-

The cholinergic drugs (such as pilocarpine)

ocular pressure in the majority of fresh cases of

and the anticholinesterase drugs

(such as

glaucoma falls to within the normal range.

echothiopate iodide) act by increasing the rate

After about 4 h, the intraocular pressure begins

of outflow of aqueous, whereas timolol is

to rise again and the side effects wear off. This,

thought to inhibit the production of aqueous.

of course, means that a further drop of pilo-

Adrenaline drops also have the effect of reduc-

carpine must be instilled if good control is to be

ing aqueous production and they have been in

continued. It is here that we find the most

use for some years as a supplement to pilo-

difficult problem of treatment. Human nature is

carpine. However, their effect is not powerful

such that drops are rarely instilled four times

and they tend to cause chronic dilatation of

daily on a regular basis, although patients are

the conjunctival vessels in some patients, as well

Table 12.1. Topical glaucoma medication.

Drug type

Examples

Mechanism of action

ß-Blockers

Timolol

Reduce aqueous production

Betaxolol

Levubunolol

Carteolol

Cholinergics

Parasympathomimetics:

Increase aqueous outflow through

Pilocarpine

trabecular meshwork

Anticholinesterases:

Phospholine iodide

Adrenergic agonists

Adrenaline and prodrug

Decrease aqueous production and

(Dipivefrine)

increase uveoscleral outflow

a₂-Agonist

Brimonidine

Carbonic anhydrase

Dorzolamide

Reduce aqueous production

inhibitors

Prostaglandins

Latanoprost

Increased uveoscleral outflow

(prostaglandin 2a)

Common Eye Diseases and their Management

as the deposition of pigment in the conjunctiva

operations have been devised for the manage-

and subconjunctival fibrosis.

ment of primary open-angle glaucoma and

Oral acetazolamide is only occasionally used

most of these entail allowing the aqueous to

in chronic glaucoma because of its long-term

drain subconjunctivally through an artificial

side effects. Acetazolamide (Diamox) is a car-

opening made in the sclera. The commonest

bonic anhydrase inhibitor, which was intro-

operation performed currently is known as

duced many years ago as a diuretic. Its diuretic

“trabeculectomy”. In this operation, a

action is not well sustained, but it is a potent

superficial “trapdoor” of sclera is raised and the

drug for reducing intraocular pressure. If a

deeper layer, including the trabecular mesh-

normal subject takes a 250-500 mg tablet of the

work, is removed. The trapdoor is then sutured

drug, the eye becomes soft after about an hour.

back into position. Aqueous drains out around

Most patients taking acetazolamide experience

the edge of this scleral flap into the subcon-

paresthesiae of the hands and feet and some

junctiva (Figure 12.5). Although most of these

complain of gastric symptoms. Occasionally,

operations can reduce the intraocular pressure

patients become lethargic or even confused.

effectively and often for many years, they all

Young patients, particularly young males, could

tend to increase the rate of formation of

suffer renal colic. It should be pointed out that

cataract. This and the risk of postoperative

these more serious side effects are rare, and

endophthalmitis are the main reasons why

long-term acetazolamide is still sometimes

surgery is usually not considered the first line of

used when no other means of controlling the

treatment in chronic open-angle glaucoma by

intraocular pressure is available.

most ophthalmologists. Often, such surgery is

Newer glaucoma medications include

augmented by the use of antifibrotic agents per-

latanoprost, dorzolamide and brimonidine.

operatively, such as

5-fluorouracil and mito-

Latanoprost is a prostaglandin analogue, which

mycin C. These agents inhibit fibroblast activity,

produces its intraocular pressure-lowering

and increase the success rate of surgery, but

effect through increased uveoscleral outflow.

carry potential side effects and need to be used

The main side effects are slight conjunctival

cautiously.

congestion (hyperaemia) and increased iris pig-

In some patients, laser treatment known as

mentation in some patients with mixed coloured

“cyclodiode” is applied externally to the eye to

irides. Prostaglandin analogues are licensed as

lower intraocular pressure by ablating part of

first-line medication for glaucoma and have

the ciliary body (this area produces the aqueous

superseded beta-blockers in effectiveness and

humour). Such treatment, however, is irrever-

tolerability. Other prostaglandin-related medi-

sible, and although easier to perform than

cations include bimatoprost

(Lumigan) and

conventional glaucoma surgery, is generally

travoprost

(Travatan), which have similar

reserved for patients with advanced uncon-

mechanisms of action to latanoprost.

trolled glaucoma.

Dorzolamide

(Trusopt) and brinzolamide

(Azopt) are topically administered carbonic

anhydrase inhibitors. Their pressure-lowering

effect is inferior to that of timolol, but they are

useful adjunctive medications.

Brimonidine (Alphagan) is an a₂-adrenergic

agonist, which decreases aqueous production

and also increases the uveoscleral outflow. It has

a pressure-lowering effect comparable with that

of timolol. It has the advantage of not having

any effect on the respiratory system. It can,

therefore, be used in patients with obstructive

airway disease.

If the intraocular pressure remains uncon-

trolled by safe medical treatment and there is

evidence of continued loss of visual field, surgi-

cal treatment is indicated. A large number of

Figure 12.5. Trabeculectomy bleb.

Glaucoma

Normal-pressure Glaucoma

fits in more closely with the popular lay idea of

“glaucoma”. It tends to affect a slightly younger

This condition is similar to primary open-

age group than chronic glaucoma and only

angle glaucoma except that the intraocular

occurs in predisposed individuals. There is a

pressure is within normal limits (i.e., 21 mmHg

particular type of eye that is liable to develop

or less at the initial and subsequent visits). The

acute glaucoma: this is a small hypermetropic

condition is probably caused by low perfusion

eye with a shallow anterior chamber. One rarely

pressure at the optic nerve head so that the

meets a myope with acute glaucoma in Cau-

nerve head is susceptible to damage at normal

casians (in Asian populations, however, angle

intraocular pressure.

closure and myopia more often coexist).

Certain conditions that can mimic normal

pressure glaucoma include compressive lesions

Pathogenesis and Natural History

of the optic nerve and chiasma, carotid ischemia

Eyes that are predisposed to develop closed-

and congenital optic disc anomalies.

angle glaucoma generally have a shallow anter-

Treatment of normal-pressure glaucoma

ior chamber and are often hypermetropic. There

aims to reduce intraocular pressure to 12 mmHg

is forward bowing of the iris, which is more

or less.

evident in these individuals, and the corneal

diameter is slightly smaller than in normal eyes.

Management

Another factor is the gradual, but slight, increase

in size of the lens, which takes place with ageing.

Most eye units now run special clinics for

Raised intraocular pressure in angle closure is

dealing with glaucoma patients. From what has

caused by occlusion of the angle by the iris root

been said, it should be clear that patients with

and it can be precipitated by dilating the pupil.

glaucoma require much time and attention.

An uncontrolled acute attack of glaucoma can

Initially, the nature of the disease must be

lead to rapid and permanent loss of the sight of

explained and patients must realise that the

the affected eye. Although it is known that occa-

treatment is to arrest the progress of the cond-

sionally patients recover spontaneously from

ition and not to cure it. Furthermore, any visual

such an attack, they could be left with chronic

loss that occurs is irretrievable, so that regular

angle closure and a picture similar to that of

follow-up visits are essential for checking the

chronic open-angle glaucoma. About half the

intraocular pressure and carefully assessing the

patients with closed-angle glaucoma will

visual fields.

develop a similar problem in the other eye if

The initial treatment is a single topical

steps are not taken to prevent this, and it will be

agent - usually a prostaglandin analogue. The

seen that prophylactic treatment for the other

second-line treatments of choice are beta-

eye is now the rule.

blockers, brimonidine or dorzolamide. Com-

monly, patients with glaucoma require several

Symptoms

different medications to control intraocular

pressure effectively.

The subacute attack. Here, it might be helpful to

Increasingly, optometrists are providing

consider a typical patient, who might be a male

specialist care for patients with glaucoma.

or female, aged about 50 years. Such a patient

Some optometrists work alongside hospital

would have a moderate degree of hyper-

consultant-led teams, others work in the com-

metropia and rather a narrow gap between iris

munity to “refine referrals” and reduce the

and cornea, as shown by the shallow anterior

number of false-positive referrals to a specialist

chamber. During the autumn months, this

glaucoma clinic.

patient’s pupil might be noted to be slightly

wider, as one might expect with the dimmer illu-

mination, and one evening the pupil dilates

Acute Angle-closure Glaucoma

sufficiently to allow the iris root to nudge across

This condition is less common than chronic

the angle and obstruct the flow of aqueous.

open-angle glaucoma, making up about 5% of

Immediately, the intraocular pressure rises

all cases of primary glaucoma. It is a much more

acutely, perhaps to 30 mmHg or 40 mmHg and

dramatic condition than the chronic disease and

pain is felt over the eye. At the same time, the

Common Eye Diseases and their Management

acute rise of pressure causes the cornea to

become oedematous. Because it is evening, the

patient observes that streetlights when viewed

through the oedematous cornea appear to have

coloured rings around them, as if they were

being viewed through frosted glass. At this

point, the patient retires to bed and on sleeping

the pupil becomes small and the intraocular

pressure rise is relieved. After several of these

attacks, the patient might seek attention from

the family doctor. Patients present as healthy

people with evening headaches associated with

blurring of the vision and they are wearing

moderately thick convex lenses in their specta-

cles. Subacute glaucoma is easily missed, partly

Figure 12.6. Acute angle-closure glaucoma.

because it is rare among the large number of

sufferers from headache. If attention is not

sought at this stage or if the diagnosis is missed,

palpating it through the eyelids will elicit

one evening the acute attack develops.

another sign, that of tenderness of the globe.

The acute attack. After a number of subacute

The visual acuity might be reduced to “hand

attacks, an irreversible turn of events can occur.

movements” in a severe attack. There are two

The iris root becomes congested, raising the

rather subtle signs that often persist perm-

intraocular pressure further and producing

anently after the acute attack has been resolved.

further congestion. The headache becomes

The first is the presence of a white, irregular

much worse and the vision becomes seriously

microscopic deposit just deep to the anterior

impaired. The doctor, who might be called in the

surface of the lens, and the second is the pres-

following morning, is confronted with a patient

ence of whorl atrophy in the iris. The pattern of

who is nauseated and vomiting and at first sight,

the iris becomes twisted as if the sphincter has

an acute abdominal problem might be sus-

been rotated slightly. Both these signs can

pected, until the painful red eye should make

provide useful evidence of a previous attack that

the diagnosis obvious. Sometimes acute glau-

has resolved spontaneously.

coma does not cause much pain or nausea

Measurement of the intraocular pressure at

and in these cases, the physical signs in the eye

this point could reveal a reading of 70 mmHg or

become especially important (Figure 12.6).

more. Gentle palpation of the globe is usually

enough to confirm that the eye has the consis-

Signs

tency of a brick, especially when the pressures

of the two eyes are compared. It should be

The most obvious physical sign is the semi-

realised that digital palpation of the globe can

dilated fixed pupil. The iris and the constricting

be misleading and the method cannot be used

sphincter muscle of the pupil are damaged by

to detect smaller rises in intraocular pressure

the raised intraocular pressure. The pupil is

with any degree of reliability (Table 12.2).

not able to constrict and after a day or two the

Examination of the other eye will reveal a

iris becomes depigmented, taking on the grey

shallow anterior chamber. Shining a focused

atrophic colour that gave glaucoma its name.

Prompt and effective treatment should prevent

any damage to the iris. The eye is red and a pink

Table 12.2. Signs of acute glaucoma.

frill of engorged deeper capillaries is seen

around the corneal margin; this important sign,

•

Corneal oedema with resulting poor visual acuity

as opposed to conjunctival inflammation, is

•

Shallow anterior chamber

•

Ciliary injection

known as ciliary injection. Corneal oedema can

•

Semidilated oval pupil (caused by iris ischaemia)

usually be detected without optical aids by

•

Tenderness of globe

observing the lack of luster in the eye and any

•

Hard eye

attempts to assess the hardness of the eye by

Glaucoma

beam of light obliquely through the cornea and

ured before he or she is seated in a darkened

noting the width of the gap between where the

room for half an hour. The intraocular pressure

light strikes the cornea and where it strikes

is again measured immediately after this, and a

the iris can assess the depth of the anterior

rise in pressure of more than 5 mmHg can be

chamber. After inspecting a few normal eyes in

taken to be significant. Certain drugs can have

this way, the observer can soon learn when an

a similar effect by having a mildly mydriatic

anterior chamber is abnormally shallow. This

action when taken by mouth. The pheno-

facility is important to anyone who intends to

thiazines have been incriminated in this respect.

instill mydriatic drops into an eye. A shallow

Of course, such drugs will have no adverse effect

anterior chamber does not contraindicate

on patients who have already been treated and

mydriatic drops but it does indicate the need for

identified as cases of narrow- or closed-angle

extreme caution and care that the pupil is after-

glaucoma. Only in unsuspected cases of sub-

wards restored to its normal size. The angle of

acute narrow-angle glaucoma is there a real risk

the anterior chamber itself is not exposed to

of precipitating an acute attack.

direct inspection and it can only be seen through

a gonioscope (Figure 12.7). This instrument is a

Treatment

contact lens with a mirror mounted on it and

through it, the width of the angle can be esti-

Acute narrow-angle glaucoma is a surgical

mated. If the angle is open, the various struc-

problem and any patient suffering from the con-

tures adjacent to the iris root and inner surface

dition requires urgent admission to hospital. To

of the peripheral cornea can be identified.

do less than this is to undertreat the condition

Gonioscopy forms a routine part of the exam-

and run the risk of producing chronic narrow-

ination of any patient with glaucoma, although

angle glaucoma. On admission, the affected eye

in acute narrow-angle glaucoma the presence of

is treated with intensive miotic drops. A typical

a closed angle can often be presumed by the

regimen would be the application of pilocarpine

presence of the other physical signs.Where there

4% every minute for 5min, then every 5min

is any doubt, it might be necessary to apply a

for an hour, followed by instillation every hour.

drop of hypertonic glycerol to the cornea to clear

This treatment is supported by an injection

the oedema before applying the gonioscope.

of acetazolamide. If the renal function is unim-

The sooner closed-angle glaucoma is diag-

paired, acetazolamide can be given intra-

nosed and treated, the better are the results of

venously (usually 500 mg) followed by an oral

treatment. Unfortunately, it is in the early sub-

dose of 250 mg four times a day. Topical beta-

acute stage of the disease that the diagnosis can

blockers and/or alpha-agonists, for example

be difficult. A number of provocative tests have

apraclonidine

(Iopidine), and reduction of

been devised for the patient who presents with

inflammation and iris congestion by topical

suspicious symptoms but a normal intraocular

steroids can help achieve a quicker lowering

pressure. The simplest test is the “dark room

of intraocular pressure. In many cases, these

test”. The patient’s intraocular pressure is meas-

measures relieve the acute attack within hours.

However, some patients can require an intra-

venous infusion of mannitol. During this period,

the patient is kept in bed and analgesics are given

if required. It is important that the other eye is

also treated with pilocarpine 2% four times a day

in order to prevent a second disaster.

Once the intraocular pressure has been con-

trolled, the cure is maintained by performing a

peripheral iridotomy or iridectomy. This allows

the bulging iris bombe to sink backwards like a

punctured ship’s sail and is a sure means of pre-

venting further acute attacks. Usually, the fellow

eye is at risk of a similar problem and is lasered

at the same time. In some patients, the angle of

Figure 12.7. Preparing for gonioscopy.

the anterior chamber remains partially occluded

100

Common Eye Diseases and their Management

by peripheral adhesions from the iris. In these

pinkish hue to the iris and is termed rubeosis

cases, a simple peripheral iridectomy might not

iridis. Patients with a central retinal vein throm-

be adequate and it might be necessary to carry

bosis followed by secondary glaucoma have

out a drainage operation, such as a trabeculec-

another problem because there is a recognised

tomy. Most patients with acute narrow-angle

association between chronic open-angle glau-

glaucoma are cured by surgery, although a small

coma and central retinal vein occlusion. This

proportion develops cataracts in later years. The

means that some patients who present with an

prognosis in adequately treated narrow-angle

occluded vein are found to have chronic glau-

glaucoma is, therefore, good, but in the absence

coma in the other eye.

of treatment the result is disastrous.

Diabetes. Patients with severe diabetic

The treatment of narrow-angle glaucoma has

retinopathy can also develop rubeosis iridis and

undergone a small revolution over the past few

secondary glaucoma. The vascular occlusive fea-

years. This is because a new generation of lasers

tures of diabetic eye disease give it many resem-

has appeared, which make it possible to perfor-

blances to central retinal vein thrombosis and

ate the iris quite simply. The yttrium-

the secondary glaucoma that develops is also

aluminum-garnet (YAG) laser has replaced sur-

resistant to medical treatment. Panretinal

gical iridectomy in most cases. A special contact

laser photocoagulation, when applied early,

lens is used to focus the laser on the peripheral

causes regression of the rubeosis. The ultimate

iris, and one or two full-thickness openings in

outcome is sometimes a blind and painful eye,

the peripheral iris are created. Following such

which has to be removed.

laser treatment, topical steroids and pupil

dilatation are given to minimise the effects of

Secondary to Uveitis

uveitis. Occasionally, trabeculectomy surgery is

During an attack of acute iridocyclitis the

performed if intraocular pressures remain per-

intraocular pressure is often below normal

sistently high despite other treatments.

because the production of aqueous by the ciliary

body is reduced. When the normal production

of aqueous is resumed, it can induce a rise in

Secondary Glaucoma

pressure because the outflow channels have been

obstructed by inflammatory exudate. This type

The intraocular pressure can become raised as

of secondary glaucoma responds to vigorous

the result of a number of different disease

treatment of the iridocyclitis, and here it is

processes in the eye quite apart from the

essential to dilate and not constrict the pupil and

causes of primary glaucoma, which have just

to apply steroid treatment. Acetazolamide and

been described.

topical beta-blockers, for example timolol and

levubunolol, might also be required. The type of

Secondary to Vascular Disease in the Eye

secondary glaucoma that develops after the

iridocyclitis of herpes zoster infections can be

Central retinal vein thrombosis. This is a

particularly insidious. The intraocular pressure

common cause of sudden blurring of the vision

can remain high without obvious pain and with

of one eye in the elderly. The retinal veins can

relatively slight inflammatory changes in the

be seen to be dilated and surrounded by haem-

eye. Secondary glaucoma usually responds well

orrhages. In some cases, recovery is marred by

to treatment and once the underlying inflam-

a rise in intraocular pressure, which typically

mation has subsided, the eye returns to normal.

appears approximately three months after the

In iridocyclitis, glaucoma can also be caused

onset of the condition. The prompt appearance

by pupil block (inability of aqueous to pass from

of this painful complication has given it the

the posterior to anterior chamber) because of

name of “hundred-day glaucoma”. This type of

posterior synechiae (adhesions between the iris

glaucoma is usually difficult to control and even

and lens). Treatment is YAG laser iridotomy.

surgical measures can prove ineffective. A

typical feature is the appearance of a vascular

Secondary to Tumours

membrane over the anterior surface of the

iris and sometimes the angle of the anterior

Malignant melanoma of the choroid and

chamber. This vascularised tissue lends a

retinoblastoma can cause glaucoma. The raised

Glaucoma

101

intraocular pressure can be an important diag-

glaucoma. Removing the lens relieves the situa-

nostic feature when a suspected lesion is seen in

tion. Phacolytic glaucoma occurs when a mature

the fundus. When a patient presents with a blind

cataract causes a type of uveitis. This is thought

glaucomatous eye, the possibility of malignancy

to result from leakage of lens proteins through

must always be in the back of one’s mind.

the lens capsule. A dislocated or subluxated lens,

either the result of trauma or as a congenital

abnormality, can be associated with a rise in

Secondary to Trauma

intraocular pressure.

Trauma can precipitate a rise in intraocular

pressure in a number of different ways. Some-

Congenital or Developmental

times, especially in children, bleeding can occur

Glaucoma

into the anterior chamber after a contusion

injury. This can seriously obstruct the flow of

These glaucomas occur in eyes in which an

aqueous both through the pupil and into the

anomaly present at birth produces an intra-

angle. Such an episode of bleeding can occur on

ocular pressure rise.

the second or third day after the injury, turning

This type of glaucoma is extremely rare and

a slight event into a very serious problem. On

it is often, though not always, inherited. This

other occasions, a contusion injury might cause

means that the affected child might be brought

splitting or recession of the angle, which is

to the ophthalmologist by the parents because

associated with glaucoma. The iridocyclitis

they are aware of the condition in the family.

that follows perforating injuries tends to be

Children could be born with raised intraocular

complicated by glaucoma and the ophthalmol-

pressure and for these cases, the prognosis is not

ogist must be constantly aware of such

so good as in those where the pressure rise does

a complication.

not occur until after the first few months of life.

In primary developmental glaucoma, the

glaucoma is caused by a defective development

Drug-induced Glaucoma

of the angle of the anterior chamber, and

Local and systemic steroids can cause a rise in

gonioscopy shows that the normal features of

intraocular pressure and this is more likely to

the angle are obscured by a pinkish membrane.

occur in patients with a family history of glau-

Raised intraocular pressure in infancy has a

coma. Steroid glaucoma is a well-recognised

dramatic effect because it causes enlargement

phenomenon and “steroid responders” can be

of the globe. This can best be observed by

identified by measuring the intraocular pressure

noting an increase in the corneal diameter. The

before and after instilling a drop of steroid. The

enlarged eye has given the condition the name

less potent steroids, hydrocortisone and pred-

of buphthalmos or “bull’s eye” (Figure 12.8).

nisolone, are less likely to cause this problem

and other steroids have been manufactured that

have less effect on intraocular pressure, but

the anti-inflammatory strength is significantly

weaker. The use of systemic steroids can be

associated with glaucoma; asthmatics who use

steroid inhalers frequently are at a significantly

greater risk of developing glaucoma.

The possibility of inducing an attack of acute

glaucoma by drugs has already been mentioned.

Secondary to Abnormalities in the Lens

A cataractous lens can become hypermature

and swell up, pushing the iris diaphragm

forward and obstructing the angle of the anter-

Figure

12.8. Congenital glaucoma: note the enlarged left

ior chamber. This is referred to as phacomorphic

cornea (with acknowledgement to Mr R. Gregson).

Retinal Detachment

Detachment of the retina signifies an inward

year age group. There is a smaller peak in the

separation of the sensory part of the retina from

mid-20s to 30s owing to traumatic detachments

the retinal pigment epithelium (RPE). There is

in young males.

an accumulation of fluid in the space between

Certain groups of people are especially liable

the neural retina and the RPE known as subreti-

to develop detachment of the retina: severely

nal fluid (Figure 13.1). The retina bulges inwards

shortsighted patients have been shown to have

like the collapsed bladder of a football. Once

an incidence as high as

3.5% and about

detached, the retina can no longer function and,

1% of aphakic patients (see Chapter 11) have

in humans, it tends to remain detached, unless

detachments.

treatment is available.

In just under one-quarter of cases,if there is no

Although the condition is relatively rare in

intervention, the other eye becomes affected at

the general population, it is important for

a later date. This means that the sound eye must

several reasons. First, it is a blinding condition

be examined with great care in every instance.

that can be treated effectively and often dra-

matically by surgery. Second, retinal detach-

ment can on occasions be the first sign of

malignant disease in the eye. Finally, nowadays

Pathogenesis

the condition can often be prevented by pro-

phylaxis in predisposed eyes.

There is an embryological explanation for

retinal detachment in that the separating layers

open up a potential space that existed during the

Incidence

early development of the eye, as described pre-

viously (Chapter 2). The inner lining of the eye

Retinal detachment is rare in the general pop-

develops as two layers. In its earliest stages of

ulation but an eye unit serving a population of

development, the eye is seen as an outgrowth

500,000 might expect to be looking after three

of the forebrain, the optic vesicle, the cavity of

or four cases a week. It can be seen, therefore,

which is continuous with that of the forebrain.

that a doctor in general practice might see a case

The vesicle becomes invaginated to form the

once in every two or three years, especially if we

optic cup, and the two-layered cup becomes the

consider that some retinal detachment patients

two-layered lining of the adult eye. Anteriorly in

go directly to eye casualty departments without

the eye, the two layers line the inner surface of

seeking nonspecialist advice. Although children

the iris and ciliary body. Posterior to the ciliary

are sometimes affected, the incidence increases

body, the outer of the two layers remains as a

with age and reaches a maximum in the 50-60-

single layer of pigmented cells, known as the

103

104

Common Eye Diseases and their Management

tractional retinal detachment, and exudative

retinal detachment.

Rhegmatogenous

Retinal Detachment

This is the most common form of retinal

detachment, caused by the recruitment of fluid

from the vitreous cavity to the subretinal space

via a full-thickness discontinuity

(a retinal

“break”) in the sensory retina.

Retinal “breaks” can be further subdivided

into “tears”, which are secondary to dynamic

Figure 13.1. Histology of retinal detachment showing the

vitreoretinal traction, and “holes”, which are the

location of subretinal fluid.This eye has an underlying choroidal

result of focal retinal degeneration (see below).

melanoma.

Tractional Retinal Detachment

pigment epithelium. The inner of the two layers

This form of retinal detachment develops as a

becomes many cells thick and develops into the

result of tractional forces within the vitreous gel

sensory retina. In the adult, the sensory retina is

pulling on the retina, causing the retina to

closely linked, both physically and metabol-

be tented up from the RPE. The pure form of

ically, with the RPE and, in particular, the

tractional retinal detachment is different from

production of visual pigment relies on this

rhegmatogenous retinal detachment in that

juxtaposition. When the retina becomes

there are no retinal breaks. Examples of trac-

detached and the sensory retina is separated

tional retinal detachment include proliferative

from the RPE, the retina can no longer function

diabetic retinopathy and vitreomacular traction

and the sight is lost in the detached area. Both

syndrome.

RPE and sensory retina are included in the term

“retina” and in this sense “retinal detachment”

Exudative Retinal Detachment

is a misnomer.

This group of retinal detachments also occurs in

The retina receives its nourishment from two

the absence of retinal breaks. The fluid gains

sources: the inner half deriving its blood supply

access to the subretinal space through an

from the central retinal artery, and the outer half

abnormal choroidal circulation (e.g., from a

from the choroid. The important foveal region

choroidal malignant melanoma) or, rarely, sec-

is supplied mainly by the choroid. When the

ondary to inflammation of the RPE or deeper

retina is detached, the central retinal artery

layers of the eye (e.g., scleritis).

remains intact and continues to supply it

because it is also detached with it. The outer

half of the retina is deprived of nourishment,

Rhegmatogenous

being separated from the RPE and choroid.

Eventually degenerative changes appear, the

Retinal Detachment

fovea being affected at an early stage. It is inter-

esting that after surgical replacement the retina

The Presence of Breaks in

regains much of its function during the first few

Retinal Detachment

days but further recovery can occur over as long

a period as one or even two years.

It was noticed as long ago as 1853, only a short

time after the invention of the ophthalmoscope,

that many detached retinae have minute full-

Classification

thickness discontinuities (breaks) in them, but

it was not until the 1920s that the full signific-

Detachment of the retina can be classified as

ance of these breaks as the basic cause of the

follows: rhegmatogenous retinal detachment,

detachment became realised. The breaks can

Retinal Detachment

105

be single or multiple and are more commonly

original position again. The vitreous is usually

situated in the anterior or more peripheral part

perfectly transparent but most people become

of the retina. In order to understand how these

aware of small particles of cellular debris, which

breaks occur, it is necessary to understand

can be observed against a clear background

something of retinal degeneration and vitreous

such as a blue sky or an X-ray screen (vitreous

changes.

floaters). These particles can be seen to move

slowly with eye movement and appear to have

momentum, just as one would expect if one con-

Retinal Degeneration

siders the way the vitreous moves.

When examining the peripheral retina of other-

wise normal subjects, it is surprising to find that

Posterior Vitreous Detachment

from time to time there are quite striking degen-

erative changes. Perhaps this is not so surprising

Vitreous floaters are commonplace and tend to

when one considers that the retinal arteries are

increase in number as the years pass. But the vit-

end arteries and these changes occur in the

reous undergoes a more dramatic change with

peripheral parts of the retina supplied by the

age. Often in the late 50s, it becomes more fluid

distal part of the circulation. Peripheral retinal

and collapses from above, separating from its

degenerations are more commonly seen in

normal position against the retina and event-

myopic eyes, especially in association with

ually lying as a contracted mobile gel in the

Marfan’s and Ehlers-Danlos syndromes and

inferior and anterior part of the cavity of the

Stickler’s disease (see reading list).

globe. The rest of the globe is occupied by clear

Different types of degeneration have been

fluid. This then is the process known as poste-

described and named and certain types are

rior vitreous detachment (PVD).

recognised as being the precursors to formation

When this happens, the patient might com-

of retinal breaks. The most important degener-

plain of something floating in front of the vision

ations are lattice degeneration and retinal tufts.

and also the appearance of flashing lights. This

Lattice degenerations consist of localised areas

is because the mobile shrunken vitreous some-

of thinning in the peripheral retina. Progressive

times causes slight traction on the retina. As a

thinning of the retina within areas of lattice

rule, the same symptoms are then experienced

degeneration can eventually lead to formation

subsequently in the other eye. On the other

of retinal “holes”.

hand, it is also common to find a detached vit-

In addition, both lattice degenerations and

reous in an elderly person’s eye in the absence

retinal tufts also represent areas with abnor-

of any symptoms.

mally strong adhesions between the vitreous

and the retina. The presence of exaggerated

Retinal Breaks Formation

vitreoretinal adhesions can result in the for-

mation of retinal “tears” within areas of lattice

In the majority of eyes the vitreous separates

degeneration and retinal tufts during posterior

“cleanly” from the retina during PVD. Such

vitreous detachment (see below).

“uncomplicated” PVD is common and is usually

of no pathological significance. Unfortunately,

on rare occasions, the collapsing vitreous causes

The Vitreous

a retinal “tear” to form at a point of abnormally

The normal vitreous is a clear gel, which occu-

strong adhesion between vitreous and retina, for

pies most of the inside of the eye. Its consistency

example within an area of lattice degeneration or

is similar to that of raw white of egg and, being

retinal tufts. There might even be an associated

a gel, it takes up water and salts. It is made up of

vitreous haemorrhage, when the PVD causes the

a meshwork of collagen fibres whose interspaces

avulsion of a peripheral retinal blood vessel.

are filled with molecules of hyaluronic acid. The

vitreous is adherent to the retina at the ora

Mechanism of Rhegmatogenous

serrata (junction of ciliary body and retina) and

Retinal Detachment

around the optic disc and macula. If we move

our eyes, the vitreous moves, and, being

Once a retinal tear forms as a result of abnor-

restrained by its attachment, swings back to its

mal vitreous traction following PVD, the fluid

106

Common Eye Diseases and their Management

from within the vitreous cavity can gain access

can save sight and they will, therefore, be con-

to the subretinal space through the retinal tear.

sidered in more detail.

The progressive accumulation of fluid in the

subretinal space eventually causes the retina to

Flashes (“Photopsiae”)

separate from the underlying RPE, similar to

wallpaper being stripped off a wall. This inward

When questioned, the patient usually says that

separation of the retina from the RPE through

these are probably present all the time but are

the recruitment of fluid via a retinal break is

only noticeable in the dark. They seem to be

the basis for “rhegmatogenous” retinal detach-

especially apparent before going to sleep at

ment, which is the most common form of

night. The flashes are usually seen in the periph-

retinal detachment.

eral part of the visual field. They must be dis-

tinguished from the flashes seen in migraine,

which are quite different and are usually fol-

Rhegmatogenous Retinal

lowed by headache. The migrainous subject

tends to see zig-zag lines, which spread out from

Detachment Associated

the centre of the field and last for about 10 min.

with Trauma

Elderly patients with a defective vertebrobasilar

circulation may describe another type of pho-

Most rhegmatogenous retinal detachments

topsia in which the flashing lights tend to occur

occur as a result of spontaneous PVD-induced

only with neck movements or after bending.

retinal breaks. However, retinal tears can also

occur as a result of trauma. A perforating injury

of the eye can produce a tear at any point in the

Floaters

retina, but contusion injuries commonly

It has already been explained that black spots

produce tears in the extreme retinal periphery

floating in front of the vision are commonplace

and in the lower temporal quadrant or the super-

but often called to our attention by anxious

ior nasal quadrant. This is because the lower

patients. When the spots are large and appear

temporal quadrant of the globe is most exposed

suddenly, they can be of pathological

to injury from a flying missile, such as a squash

significance. For some reason, patients often

ball. The threatened eye makes an upward

refer to them as tadpoles or frogspawn, or even

movement as the lids attempt to close. Tears of

a spider’s web. It is the combination of these

this kind often take the form of a dialysis, the

symptoms with flashing lights that makes

retina being torn away in an arc from the ora

it important.

serrata. Warning symptoms in these patients are

Flashes and floaters appear because the vit-

usually masked by the symptoms of the original

reous has tugged on the retina, producing the

injury and they tend to present some months, or

sensation of light, and often when the tear

occasionally years, after the original injury with

appears there is a slight bleeding into the vit-

the symptoms of a retinal detachment. This is

reous, causing the black spots. When clear-cut

unfortunate because the tear can be treated if it

symptoms of this kind appear, they must not be

is located before the detachment occurs.

overlooked. The eyes must be examined fully

until the tear in the retina is found. Sometimes,

a small tear in the retina is accompanied by a

Signs and Symptoms

large vitreous haemorrhage and thus sudden

loss of vision.

of Retinal Tear and

Retinal Detachment

Shadow

Let us now consider a typical patient, possibly a

Once a retinal tear has appeared, the patient

myope in the mid-50s, either male or female,

might seek medical attention, and effective

who suddenly experiences the symptoms of

treatment of the tear can ensue. Unfortunately,

“flashes and floaters”, sometimes spontaneously

some patients do not seek attention, or, if they

or sometimes after making a sudden head move-

do, the symptoms might be disregarded. Indeed,

ment. Proper interpretation of such symptoms

in time the symptoms might become less, but

Retinal Detachment

107

after a variable period between days and years,

Exudative Retinal

a black shadow is seen encroaching from the

peripheral field. This can appear to wobble. If

Detachment

the detachment is above, the shadow encroaches

from below and it might seem to improve spon-

In such detachments, there are no photopsiae

taneously with bedrest, being at first better in

but floaters can occur from associated vitritis or

the morning. Loss of central vision or visual

vitreous haemorrhage. A visual field defect is

blurring occurs when the fovea is involved by

usual. Exudative detachments are usually convex

the detachment, or the visual axis is obstructed

shaped and associated with shifting fluid.

by a bullous detachment. Inspection of the

A malignant melanoma of the choroid might

fundus at this stage shows that fluid seeps

present as a retinal detachment. Often the

through the retinal break, raising up the sur-

melanoma is evident as a black lump with an

rounding retina like a blister in the paintwork

adjacent area of detached retina. If the retina is

of a car. A shallow detachment of the retina can

extensively detached over the tumour, the diag-

be difficult to detect but the affected area tends

nosis can become difficult. It is important to

to look slightly grey and, most importantly, the

avoid performing retinal surgery on such a case

choroidal pattern can no longer be seen. The

because of the risk of disseminating the tumour.

analogy is with a piece of wet tissue stuck

Suspicion should be raised by a balloon detach-

against grained wood. If the tissue paper is

ment without any visible tears, and the diag-

raised slightly away from the wood, the grain is

nosis can be confirmed by transilluminating the

no longer visible. As the detachment increases,

eye to reveal the tumour.

the affected area looks dark grey and corrugated

Retinal detachments secondary to inflam-

and the retinal vessels look darker than in flat

matory exudates are not common. One example

retina. The tear in the retina shines out red as

is Harada’s disease, which is the constellation of

one views the RPE and choroid through it.

exudative uveitis with retinal detachment,

Once a black shadow of this kind appears in

patchy depigmentation of the skin, meningitis

front of the vision, the patient usually becomes

and deafness. Its cause is unknown. Exudative

alarmed and seeks immediate medical atten-

detachments do not require surgery but treat-

tion. Urgent admission to hospital and retina

ment of the underlying cause.

surgery are needed.

Management of

Rhegmatogenous Retinal

Tractional Retinal

Detachment

Prophylaxis

In tractional retinal detachment, the retina can

be pulled away by the contraction of fibrous

Retinal tears without significant subretinal fluid

bands in the vitreous. Photopsiae and floaters

can be sealed by means of light coagulation. A

are usually absent but a slowly progressive

powerful light beam from a laser is directed at

visual field defect is noticeable. The detached

the surrounds of the tear (Figure 13.2). This pro-

retina is usually concave and immobile.

duces blanching of the retina around the edges

Advanced proliferative diabetic retinopathy

of the hole and, after some days, migration and

can be complicated by tractional retinal detach-

proliferation of pigment cells occurs from the

ment of the retina when a contracting band tents

RPE into the neuroretina and the blanched

up the retina by direct traction. Not infrequently

area becomes pigmented. A bond is formed

such a diabetic patient experiences further

across the potential space and a retinal detach-

sudden loss of vision in the eye, when the trac-

ment is prevented. This procedure can be

tion exerted by the contracting vitreous pulls a

carried out, with the aid of a contact lens, in a

hole in the area of tractional retinal detachment,

few minutes.

resulting in a combined rhegmatogenous and

A wider and more diffuse area of chorio-

tractional retinal detachment.

retinal bonding can be achieved by cryopexy,

108

Common Eye Diseases and their Management

cautery to the site of the tear combined with the

release of subretinal fluid was effective, it also

became evident that not all cases responded

to this kind of treatment. It was almost as if

the retina was too small for the eye in some

cases, an idea that led to the design of volume-

reducing operations, which effectively made the

volume of the globe smaller. This, in turn, led to

the concept of mounting the tear on an inward

protrusion of the sclera to prevent subsequent

redetachment.

Modern retinal reattachment surgery

carried out using either

the

cryobuckle

Figure

13.2. Laser photocoagulation of retinal tear

(with

vitrectomy technique.

acknowledgement to Mr R. Gregson).

which entails freezing from the outside. Cry-

opexy is occasionally necessary if the retinal

hole is peripheral, or when there is limited

blanching of the retina from laser photocoagu-

lation because of the presence of vitreous haem-

orrhage. A cold probe is placed on the sclera

over the site of the tear and an ice ball is allowed

to form over the tear. A similar type of reaction

(as occurs after photocoagulation) develops

following this treatment, but it tends to be

uncomfortable for the patient and local or

general anaesthesia is required.

Retinal Surgery

In the early part of the twentieth century, it was

generally accepted that there was no known

effective treatment for retinal detachment. It

was realised that a period of bedrest resulted in

flattening of the retina in many instances. This

entailed a prolonged period of complete

immobilisation, with the patient lying flat with

both eyes padded. This treatment can restore

the sight but only temporarily because the

retina redetaches when the patient is mobilised.

It was also dangerous for the patient in view of

the risk of venous thrombosis and pulmonary

embolism. In the 1920s, it began to be realised

that effective treatment of retinal detachment

depends on sealing the small holes in the retina

(Figure 13.3). It was already known by then that

the fluid under the retina could be drained off

externally simply by puncturing the globe, but

up till then no serious attempt had been made

to associate this with some form of cautery to

Figure

13.3.

Retinal

detachment

before

and

after

the site of the tear. Once it became apparent that

treatment. (After Gonin).

Retinal Detachment

109

Vitrectomy

The detached retina can also be reattached from

within the vitreous cavity. This involves the use

of fine-calibre instruments inserted through the

pars plana into the vitreous cavity. A light probe

is used to illuminate the operative field, while a

“vitrectomy cutter” is used to remove the vit-

reous, hence relieving the abnormal vitreous

adhesions that produced the retinal tear in the

first instance (Figure 13.5). The detached retina

is “pushed back” into place from within and

temporarily supported by an internal tamp-

onade agent (air, gas or silicone oil) while the

retina heals. The retinal breaks are identified

and treated by either laser photocoagulation or

cryopexy at the same time. Vitrectomy can also

be combined with a silicone strap encirclement

if further support of the peripheral retina

is needed.

Historically, vitrectomy is reserved for the

more difficult and complex cases of rheg-

matogenous retinal detachment, where multiple

tears and posteriorly located tears are present,

or as a “salvage” operation following failed cryo-

buckle. With advances in instruments, vitrec-

tomy is increasingly being used as the primary

operation for the repair of most acute PVD-

related rhegmatogenous retinal detachments,

regardless of the complexity of the detachment.

Prognosis

The retina can now be successfully reattached

by one operation in about 85% of cases. Of the

Figure 13.4.

a Retinal detachment surgery: retinal tear sur-

successful cases, those in which the macular

rounded by cryopexy and covered by indent. b Retinal detach-

region was affected by the retinal detachment

ment surgery: indent and encirclement band

(with

acknowledgement to Professor D. Archer).

Cryobuckle

This involves the sewing of small inert pieces of

material, usually silicone rubber, onto the

outside of the sclera in such a way as to make a

suitable indent at the site of the tear (Figure

13.4). This is combined with cryopexy to the

break. It is often necessary to drain off the sub-

retinal fluid and inject air or gas into the vit-

reous. In more difficult cases, the eye can be

encircled with a silicone strap to provide all-

round support to a retina with extensive

degenerative changes.

Figure 13.5. Vitrectomy.

110

Common Eye Diseases and their Management

do not achieve a full restoration of their central

“scarring” following initial retinal reattachment

vision, although usually the peripheral field

surgery, with the formation of fibrous tractional

recovers. The degree of recovery of central

membrane within the eye, resulting in recurrent

vision in such macula-detached cases depends

detachment of the retina.

largely on the duration of the macula detach-

When retinal surgery has failed, further

ment before surgery. Even when the retina has

surgery might be required and for a few patients

been detached for two years,it is still possible to

a series of operations is necessary. If it is

restore useful navigational vision.

thought that more than one operation is going

The main cause of failure of modern retinal

to be needed, it is helpful to the patient if he

reattachment surgery is proliferative vitreo-

is warned about this before the treatment

retinopathy. This is characterised by excessive

is started.

Squint

The word “squint” refers to a failure of the visual

fail. The ability to use the eyes together is called

axes to meet at the point of regard. For normal

binocular vision. It can be measured and graded

vision, each eye must be focused on and lined

by presenting each eye separately, but simul-

up with the object of regard. The fact that we

taneously, with a series of images. The instru-

have two eyes positioned some 60 mm apart

ment used to do this is called a synoptophore

means that we can accumulate considerably

(Figure 14.1).

more data about our environment than would

be possible with one eye alone. This can best be

1. Simultaneous macular perception is said to

exemplified by considering what happens when

be present if the subject can see two dis-

one eye is suddenly lost as the result of injury

similar images that are presented simul-

or disease. Apart from the obvious loss of visual

taneously to each eye, for example a

field, which necessitates turning the head to the

triangle to one eye and a circle to the other.

blind side, the patient experiences impaired dis-

2. Fusion is present if the subject can see two

tance judgement. The skilled worker notices a

parts of a whole image as one whole when

deterioration in the ability to perform fine tasks

each half is presented to a separate eye, for

and the elderly notice that they pour tea into the

example a picture of a house to one eye and

saucer rather than the cup. In time, depth per-

a picture of a chimney to the other, and the

ception might improve and the patient adapts to

whole picture is maintained as one as the

the defect to some extent; children can adapt

eyes converge. The range of fusion can be

to one-eyed vision in a remarkable way. But, it

measured in degrees.

seems that modern civilised living does not

3. Stereopsis, the third grade of binocular

have such great demands for binocular vision

vision, is present if, when slightly dis-

now that many tasks are carried out by

similar views of an object are presented

machines. It is no coincidence that those

to each eye separately, a single three-

animals whose survival depends on catching

dimensional view of the whole is seen.

their food by means of accurate distance judge-

Stereopsis itself can also be graded if

ment have their eyes placed in front of their

fine degrees of impairment of binocular

head, enabling the two eyes to be focused

function need to be measured.

together on their prey.

Investigation of a normal human population

This ability of ours to put together the images

reveals that although the eyes are situated on the

from each eye and make a single picture in our

front of the face, they do not always work

minds seems to develop during the early years

together, and it will be seen that there are a

of life and furthermore, its development seems

number of reasons why the mechanism might

to depend on visual input. Below the age of eight

111

112

Common Eye Diseases and their Management

Types of Squint

In lay terms, the word squint can just mean

screwing up the eyes but here we are referring

to a deviation of one eye from the line of sight.

This might be present all the time or just when

the patient is tired. It is important to notice

whether the eye movements are normal. For

example, if there is weakness of one lateral

rectus muscle, the affected eye will not turn

outward and the angle of the squint will be

much greater when looking to that side. Most

childhood squints are not associated with weak-

Figure 14.1. The synoptophore. An instrument for measuring

ness of one or more extraocular muscles so that

the angle of deviation of a squint and the ability of the eyes to

the angle of the squint is the same in all direc-

work together.

tions of gaze. The deviation of the squint can be

horizontal or sometimes vertical or the eyes

could be convergent or divergent.

years, any misalignment of the eyes that

disturbs binocular vision can permanently

damage this function.

If the alignment of the eyes is disturbed for

Squint in Childhood

any reason during childhood, the child might at

first, as one might expect, notice double vision

During the first few weeks of life the eyes might

but quickly learns to suppress the image from

seem to wander about aimlessly with limited

one eye, thereby eliminating the annoyance of

ability to fix. Between the ages of two and six

diplopia at the expense of binocular vision. In

months, fixation becomes steadier even though

fact, most, but not all, children learn to suppress

the fovea is not fully developed, and by the age

when using monocular instruments, switching

of six months convergence on a near object can

the other eye on again when the instrument is

be maintained for several seconds. Even at birth,

not being used. Prolonged suppression seems to

some degree of following movement of the eyes

lead to a more permanent state of visual loss

can be seen in response to a flashing light, but

called amblyopia of disuse. The word “ambly-

only the most gross squints can be diagnosed

opia” simply means blindness. Suppression is a

during these early months of life. If the eyes are

temporary switching off of one eye when the

definitely squinting at the age of six months,

other is in use, whereas amblyopia of disuse is a

urgent referral to an ophthalmologist is indic-

permanent impairment of vision, which could

ated. Before this or when there is some doubt,

affect the career prospects of the patient.

referral to an orthoptic screening service can

Amblyopia of disuse can also occur if the sight

be considered. These have been set up in many

of one eye is defective as the result of opacities

parts of the country. Orthoptists might be

in the media, even though the alignment of the

regarded as “physiotherapists of the eyes” and

eyes has not been disturbed. Again, this only

they are trained to examine the eye movements

occurs in children under the age of eight years.

in great detail. We need to detect squints early

Covering one eye of a baby could lead to per-

in children for the following reasons:

manent impairment of the vision of that eye, as

1. The squint could be caused by serious un-

well as impairment of the ability to use the eyes

derlying intracranial or intraocular disease.

together. An adult can have one eye covered for

many months or even years without suffering

2. The squint can result in amblyopia, which

visual loss.

is more effectively treated, the younger

Before considering the causes and effects of

the child.

squint in children and adults, it is necessary to

3. The cosmetic effect of a squint is an impor-

know something of the different kinds of squint.

tant consideration.

Squint

113

Amblyopia of Disuse

when we focus upon an object, not only is each

individual eye separately focused on it, but the

A special word is needed about this curious con-

eyes swivel together by the requisite amount to

dition, which accounts for unilateral impair-

allow them both to view the object at once. A

ment of vision in over 2% of the population. Any

given amount of accommodation must, there-

eye casualty officer is familiar with the patient

fore, be associated with an equivalent amount of

with a foreign body on the cornea of one eye

convergence. In hypermetropic subjects this

and the other eye being amblyopic. (“How can I

relationship is disturbed. In order to overcome

drive home with this patch on, doctor?”) The

hypermetropia, the eyes must accommodate

words “lazy eye” are sometimes used but in lay

and sometimes this excessive focusing induces

terms this can also mean squint.

an excess of convergence, hence causing a

The eye suffering from amblyopia of disuse

squint. This type of accommodative squint can

shows certain features:

be fully corrected by wearing spectacles: when

the glasses are on, the eyes are straight; and

• Impaired Snellen visual acuity but usually

when they are off, one eye turns in. More often,

able to decipher vertical lines of letters

the squint is only partially accommodative and

better than horizontal ones.

is improved, but not eliminated, by wearing

• Normal fundus.

glasses. The convergent squint associated with

• Small residual squint or, if not, the affected

hypermetropia is the commonest type of

eye relatively hypermetropic.

childhood squint.

• An indefinite central scotoma, which

is difficult to assess by routine visual

Opaque Media

field testing.

• History of poor vision in one eye since

Congenital cataract can occasionally present as

childhood.

a squint. In a similar manner, a corneal opacity,

as might result from herpes simplex keratitis or

The diagnosis of amblyopia can be by exclu-

injury, can cause a squint to appear. A com-

sion but it must never be reached without a

pletely blind eye from whatever cause tends to

careful examination of the eyes. In recent years,

converge if the blindness occurs in early child-

there has been a considerable research interest

hood. Blindness of one eye in an adult tends to

in this subject and there appear to be nerve con-

result in a divergent squint. This is sometimes a

duction anomalies in the occipital cortex, which

useful indicator of the age of onset of blindness.

can be induced by visual deprivation.

Disease of the Retina or Optic Nerve

Causes of Squint in Childhood

Such a possibility provides an important reason

for the careful examination of the fundus in

• Refractive error - hypermetropia, myopia.

every case.

• Opaque media

- corneal opacities,

cataract, uveitis.

• Disease of retina or optic nerve

Congenital or Acquired Muscle Weakness

retinoblastoma, optic atrophy.

Sixth, third or fourth cranial nerve palsies are

• Congenital or acquired weakness of

sometimes seen after head injuries and the

extraocular muscles.

surgeon must always bear in mind the possibil-

• Abnormalities of facial skeleton leading to

ity of a sixth or other cranial nerve palsy being

displacement of extraocular muscles.

associated with raised intracranial pressure.

Myasthenia gravis is extremely rare in children

but it can present as a squint. In some cases of

Refractive Error

squint there is a degree of facial asymmetry.

In order to understand how refractive error can

These patients might also have “asymmetrical

cause squint, one must first understand how the

eyes”, one being myopic or hypermetropic rela-

act of accommodation is linked to the act of

tive to the other. Sometimes there is no refrac-

convergence. That is to say, we must realise that

tive error but there might be an asymmetry of

114

Common Eye Diseases and their Management

the insertions of the extraocular muscles as a

possible cause of squint. There is a group of con-

ditions, known as musculofascial anomalies, in

which there is marked limitation of the eye

movements from birth in certain directions.

They are accompanied by abnormal eye move-

ments, such as retraction of the globe and nar-

rowing of the palpebral fissures on lateral gaze.

Overaction of muscles can cause a squint.

This is seen in school children sometimes with

a background of domestic or other stress. The

eyes tend to overconverge and overaccom-

modate, especially when being examined.

Abnormalities of Facial Skeleton

This is not a common cause but it should be kept

in mind.

Diagnosis

History

When faced with a case of suspected squint,

certain aspects of the history can be helpful in

assisting with the diagnosis. It is often useful

Figure 14.2.

Pseudosquint. The configuration of the eyelids

gives the appearance of a squint but the corneal reflexes show

to ask who first noticed the squint. Sometimes,

that this is not the case.

a mother has been made anxious by a well-

wishing neighbour or relative, and in these

cases, there might be no true squint but merely

the appearance of one. The mother herself is

nervous, a useful technique is to introduce

usually the best witness. Unfortunately, some

something of interest to the child in the conver-

children have a facial configuration that makes

sation with the parents. At this point, it is impor-

the eyes look as though they are deviating when

tant not to approach the child directly but to

they are not and it is essential that the student

allow him or her to make an assessment of the

or general practitioner should be able to make

doctor. It is quite impossible to examine an

this distinction in order to avoid sending unnec-

infant’s eyes in a noisy room, thus the number

essary referrals to the local eye unit (Figure

of people present should be minimal and they

14.2). Childhood squints often show a dominant

should not be moving about. The room lighting

pattern of inheritance and the family history

should be dim enough to enable the light of a

provides a useful diagnostic indicator. From the

torch to be seen easily. The first important part

point of view of prognosis, it is useful to find out

of the examination is to shine a torch at the

whether the squint is constant or intermittent

patient so that the reflection of the light can be

and also the age of onset. A full ophthalmic

seen on each cornea. The position of these

history must be taken, which should include the

corneal reflections is then noted carefully. The

birth history and any illness that might have

more mobile the child, the less time there is to

caused or initiated the problem.

observe this. If there is a squint, the reflections

will be positioned asymmetrically in the pupil.

If the patient has a left convergent squint, the

Examination

reflection from the left cornea is displaced

While the history is being taken from the

outward towards the pupil margin. A rough

parents, one should be making an assessment of

assessment of the angle of the squint can be

the child. If the child is obviously shy or

made at this stage by noting the abnormal

Squint

115

position of the reflection. One of the difficulties

produced by covering one eye is spotted by

experienced at this point is because of the con-

noting the small recovery movement made by

tinuous movement of the child’s eyes, which

the previously covered eye. Finally, the cover test

makes it difficult at first to know whether the

must be repeated with the patient looking at a

light is being accurately fixated. By gently

distant object. One type of squint in particular

moving the torch slightly from side to side, it is

can be missed unless this is done. This is the

usually possible to confirm that the child is

divergent squint seen in young children, which

looking, albeit momentarily, at the light.

is often only present when viewing distant

Once the light reflections have been exam-

objects. The parents might have noticed an

ined, the cover test can be performed. Once

obvious squint and yet testing by the doctor in

again the reflection of light from each eye is

the confines of a small room reveals nothing

noted, but this time one of the eyes is smartly

abnormal, with ensuing consternation all round.

covered, either with the back of the hand or a

After the cover test has been performed, it is

card. If the fixating eye is covered, a movement

necessary to test the ocular movements to

of the nonfixing eye to take up fixation can then

determine whether there is any muscle weak-

be observed (Figure 14.3). After some practice,

ness. At this stage, it is usual to instil a mydri-

it is possible to detect even slight movements of

atic and cycloplegic drop (e.g., cyclopentolate

this kind. The result of the test can be mislead-

1% or 0.5%) in order to obtain a measure of the

ing if the nonfixing eye is too weak to take

refractive error, by retinoscopy, when the eyes

up fixation, and quite often, an assessment of

are completely at rest. Next, the optic fundi are

the vision of the nonfixing eye can be made at

examined.

this stage.

In most instances, the nature of the squint

If, having performed this first stage of the

becomes apparent by this stage and further

cover test, no deviation can be detected, the

testing of the binocular function and more

cover can be quickly swapped from one eye to

accurate measurement of the angle of the squint

the other and any movement of the covered eye

are carried out using the synoptophore.

can be noted. That is to say, the latent deviation

Management of Squint in Childhood

Glasses

Any significant refractive error is corrected by

the prescription of glasses. Sometimes the

squint is completely straightened when glasses

are worn but more often the control is partial,

the glasses simply acting to reduce the angle of

the squint. Glasses can be prescribed in a child

Left eye covered

as young as six to nine months if really neces-

sary. It is important that the parents have a full

understanding of the need to wear glasses if

adequate supervision is to be expected. When

the spectacles are removed at bedtime, a previ-

ous squint might appear to become even worse

and the parents should be warned about this

possible rebound effect.

Right eye covered

Orthoptic Follow-up

The orthoptic department forms an integral and

important part of the modern eye unit. It is run

and manned by orthoptists who carry out the

RIGHT CONVERGENT SQUINT

careful measurement of visual acuity with and

Figure 14.3. The cover test.

without glasses and the measurement of eye

116

Common Eye Diseases and their Management

movements and binocular function. Once the

vision. Unfortunately, all too often, the first one

patient has been seen for the initial visit, follow

of these aims alone is achieved in spite of

up in the orthoptic department is arranged and

modern methods of treatment. The fault might

the question of treatment by occlusion of the

lie partly in late referral or difficulty with

good eye has to be considered. By covering

patient co-operation but better methods of

the good eye for a limited period, the sight of the

treatment are needed.

amblyopic eye can be improved. The younger the

child, the better are the chances of success. In

older children beyond the age of seven or eight

Squint in Adults

years, not only is amblyopia more resistant to

treatment, but the treatment itself can interfere

Adults who present with a squint have usually

seriously with school work. The type and

suffered defective action of one or more of the

amount of occlusive treatment have to be

extraocular muscles. It is important to have a

planned and discussed with the parents. Some-

basic understanding of these muscles.

times atropine eye drops are used as an alterna-

tive to patching one eye. Orthoptic exercises

Anatomy of the Extraocular Muscles

can also be used in an attempt to strengthen

binocular function.

The extraocular muscles can be divided into

three groups: the horizontal recti, the vertical

recti and the obliques.

Surgery

If the squint is not controlled by glasses, surgery

The Horizontal Recti

should be considered. Some parents ask if an

operation can be carried out as a substitute

The medial and lateral recti act as yoke muscles,

for wearing glasses. Unfortunately, surgery to

like the reins of a horse. They rotate the eye

correct refractive error is not yet at a stage where

about a vertical axis. The lateral rectus abducts

it can be applied to children with squints. Squint

the eye (turns it out) and the medial rectus

surgery involves moving the muscle insertions

adducts the eye (turns it in).

or shortening the muscles and from the cosmetic

point of view is highly effective. The adjustment

The Vertical Recti

of the muscles is measured in millimetres to

correspond with the angle of the squint in

These act as vertical yoke muscles but they run

degrees. Sometimes two or more operations are

diagonally from their origin at the apex of the

needed because of occasionally unpredictable

orbit to be inserted 7 mm or 8 mm behind the

results, but from the cosmetic point of view,

limbus above and below the globe. The action of

nobody need suffer the indignity of a squint,

these muscles depends on the initial position of

even though a series of operations might be

the eye. For example, the primary action of the

needed. Once the eyes have been put straight

superior rectus is to elevate the abducted eye

or nearly straight by surgery, the functional

and the inferior rectus depresses the abducted

result depends on the previous presence of good

eye. The secondary action of the superior rectus

binocular vision and good vision in each eye.

is to adduct and intort the adducted eye; the

Squint occurs in about 2% of the population

inferior rectus adducts and extorts the adducted

and so it is a common problem, but only

eye. Intorsion and extorsion refer to rotation

a small proportion of these cases eventually

about an anteroposterior axis through the

require surgery. The commonest type of squint

globe. The important thing to realise is that the

in childhood is the accommodative convergent

action of these muscles depends on the position

squint associated with hypermetropia and here

of the eye (Figure 14.4).

surgery is indicated only when spectacles prove

inadequate. Divergent squints are less common

The Obliques

but more often require early surgery.

The aim of treatment for a child with squint

These are also vertical yoke muscles but they run

is to make the eyes look straight, to make each

on a different line to the vertical recti. The supe-

eye see normally and to achieve good binocular

rior oblique depresses the adducted eye (makes

Squint

117

Intorts the adducted eye

Elevates the abducted eye

Figure 14.4. Primary and secondary actions of the superior rectus muscle.

the eye go down when it is turned in) and the

In adult life, a blind eye tends to turn out-

inferior oblique elevates the adducted eye.

wards and a divergent squint can be due solely

When a patient has a fourth cranial nerve

to impaired vision in one eye.

palsy on the right side, the right eye can no

longer look down when it is turned in because

Diagnosis

of the defective action of the superior oblique

muscle. Double vision is experienced, which is

In contrast to the situation with children, who

maximal (i.e., widest displacement of images)

usually present with concomitant squint asso-

when looking down to the left.

ciated with hypermetropia, the sudden onset of

When a patient has a sixth cranial nerve palsy

a squint in adult life is extremely disabling

on the right side, the right eye can no longer

because of intractable double vision.The double

abduct or turn outwards. A right convergent

vision is less apparent when the lesion is more

squint is seen and the patient experiences

central, involving the level of the cranial nerve

double vision, which is worse when looking to

nucleus or above. In the latter case, the patient

the right. There might be a head turn to the right.

tends to complain more of blurred vision

When a patient has a third cranial nerve palsy

and confusion.

on the right side, the right eye is turned down

A carefully taken history can reveal the diag-

and to the right and, if the palsy is complete, the

nosis. First, it is necessary to ensure that the

upper lid droops and the pupil is dilated. Move-

double vision is only present with both eyes

ment of the eye is limited.

open and then the patient can be questioned

about the position of the second image and

whether the separation of the images is maximal

Causes of Adult Squint

in any particular direction of gaze. The duration

Adults who present with a squint usually have a

and constant or intermittent nature of the squint

well-defined ocular muscle palsy. This can be

must be determined, as must the history of any

caused by a pathological process at any point

associated disease, past or present.

from the brain, through the nerve to the muscle.

Once the history has been obtained, the

This will be discussed elsewhere but two impor-

nature of the squint can be investigated by the

tant causes are disseminated sclerosis in the

cover test and measured by the Maddox wing

younger age groups and hypertensive vascular

and Maddox rod. An accurate record of the

disease in older patients. Diabetes is another

impaired muscle action can be recorded on the

important cause that must be excluded in all

Hess screen.

age groups.

Some adult squints prove to be concomitant

Maddox Wing

squints neglected from childhood. Sometimes a

latent squint, which has been well controlled

This ingenious but simple device is held in

throughout childhood, breaks down in adult life.

the patient’s hand. By looking through the

118

Common Eye Diseases and their Management

eyepieces, one eye is made to look at an arrow

of particular ocular muscle problems and serial

and the other eye at a row of numbers. If the eyes

records can be helpful in assessing progress.

are straight, the arrow points at zero, and if not,

the arrow indicates the angle of the squint.

Treatment

Many cases of adult squint recover spon-

Maddox Rod

taneously within a period of three to six

months. Once the cause of the squint has been

The Maddox wing measures the deviation at

investigated, the immediate treatment entails

reading distance and the Maddox rod is a

eliminating the diplopia by occluding one or

similar device to measure the deviation when

other eye. This can be conveniently achieved by

viewing a distant object. A special optical glass

applying adhesive tape to the spectacle lens. If

is placed in front of one eye, which turns the

the angle of the squint is sufficiently small, it

image of a light source into a line image. One

might be possible to regain binocular vision by

eye, therefore, views the point source of light

means of a prism. Fresnel prisms are thin and

and the other a line, and the separation of these

flexible and can be simply stuck onto the spec-

two images can be measured on a scale.

tacle lens as a temporary measure during the

recovery period. When the squint shows no sign

of recovery over a period of nine months or

Hess Screen

more, surgery is usually required to restore

Here, the eyes are dissociated by using either

binocular vision. Before applying these princi-

coloured filters or a mirror. The system is

ples of management, it is essential to treat the

arranged so that a screen is viewed with one eye

underlying cause of the squint. It would be a

and the end of a pointer with the other. The

serious error to treat diplopia because of raised

patient is told to place the pointer on various

intracranial pressure by means of prisms,

points on the screen. If the eyes are not straight,

without instituting a full neurological investiga-

the pointer is placed away from the correct pos-

tion, just as it would not help the patient with

ition. A map of the incorrect positions is made

myasthenia gravis to undergo squint surgery

(Figure 14.5). The shape of the map is diagnostic

before medical treatment has been started.

Figure 14.5. Hess chart depicting a right lateral rectus palsy.

Squint

119

are seen in otherwise normal individuals who

Ocular Muscle Imbalance

show a marked difference in refractive error

Mild latent squints can sometimes go undetec-

between the two eyes or in those with facial

ted until a period of stress or perhaps excessive

asymmetry. The provision of a small prism

reading precipitates symptoms of eyestrain and

incorporated into the spectacle lenses of such

headache. The effort to maintain both eyes in

patients can produce dramatic relief, but we

line causes the symptoms. The latent deviation

must always remember that the appearance of

could be inward or outward but because most

an ocular muscle imbalance might be the first

people’s eyes tend to assume a slightly divergent

indication of more serious disease. A small ver-

position when completely at rest, a degree

tical deviation can be the first sign of a tumour

of latent divergence (exophoria) is almost the

of the lacrimal gland or thyrotoxic eye disease

rule and of no significance. Vertical muscle

and a wide range of investigations might be

imbalance is less well tolerated and even a

needed before one can be satisfied with the

slight deviation can cause symptoms. Small but

excellent but sometimes deceptive results of

significant degrees of vertical muscle imbalance

symptomatic treatment.

Tumours of the Eye and Adnexae

In this chapter the more important ocular

be an associated exudative retinal detachment

tumours will be considered. There are a con-

or, less often, secondary glaucoma. Other asso-

siderable number of other rare tumours and the

ciated features might include choroidal haemor-

interested student should refer to one of the

rhage and serial photography might be needed

more specialised and comprehensive textbooks

to confirm the growth. The usual presentation is

of ophthalmology for further reading.

with decreased vision or a visual field defect.

Diagnosis is confirmed with careful clinical

examination, including indirect ophthalmo-

The Globe

scopy and slit-lamp biomicroscopy

(contact

lens or volk lens examination), fluorescein

Expanding tumours in the eye present diagnos-

angiography, ultrasonography and transvitreal

tic problems because it is not usually possible to

fine-needle aspiration in equivocal cases. The

biopsy them.

most common site for metastases is the liver,

so abdominal ultrasound, serum liver function

tests, and chest X-ray should be performed at

Choroidal Melanoma

regular intervals. The appearance of liver metas-

The most common primary intraocular tumour

tases can be delayed for several years and can

is the malignant melanoma of the choroid. In

occur even if the eye has been removed, sig-

white people, the tumour has an incidence of one

nifying micrometastases at the time of presen-

in 2500 and the average age at presentation is 50

tation. Approximately 40% of patients develop

years. The incidence rises with age with a peak

liver metastases within ten years of the initial

at 70 years. However, it is important to appre-

diagnosis, while the estimated five-year mortal-

ciate that no age is exempt because choroidal

ity rate for treated medium-size melanomas is

melanomas have been reported in children as

between 15% and 23%. The differential diagno-

young as three years. It is extremely rare in black

sis of choroidal melanoma includes retinal

people. It differs from melanoma of the skin in

detachment, metastatic choroidal tumours, wet

that it grows more slowly and metastasises late.

macular degeneration, large choroidal nevi,

Most choroidal melanomas are thought to orig-

choroidal haemangioma or choroidal effusion.

inate from choroidal nevi, which are present in

Historically, treatment involved enucleation

up to 10% of the population. At first, it is seen as

(removal of the globe); today, however, many

a raised pigmented oval area, which can be any-

alternative eye-sparing treatments are available,

where in the fundus (Figure 15.1). It is usually

partly dependent on the size and local spread

brown in colour although it can be amelanotic

of the tumour. Options include radiotherapy

(or greyish). As the tumour enlarges there might

(external plaque, proton beam or helium ion),

121

122

Common Eye Diseases and their Management

primary intraocular tumour in children, with an

incidence of one in 15,000 live births. It shows

certain rather strange and unusual features. It

is not usually present from birth, but occurs

most frequently in infancy to age three years

(although it can occur in older patients); it is

either inherited as an autosomal dominant trait

or can be sporadic in nature. Approximately

40% of cases are considered to be inherited. In

one-third of inherited cases it appears in both

eyes. A change in the RB1 gene on chromosome

13 is found in the inherited cases. Initially, it can

be seen in an individual, suspected on account

of the family history, as a small white, raised

mass. Examination under anaesthesia is essen-

tial in such cases because the tumour might be

in the extreme periphery of the fundus. A larger

tumour can present as a white mass in the pupil

(“leucocoria”) and such an appearance in

infancy demands immediate referral to an

ophthalmologist (Figure 15.2). Other presenting

features include strabismus, secondary glau-

coma, proptosis or intraocular inflammatory

signs. Computed tomography (CT) scanning

and ultrasound might show a calcified intra-

Figure 15.1.

Choroidal melanoma poorly pigmented (amelan-

ocular mass. Extension tends to occur locally

otic) melanoma a fundus photograph. b Bisected eye showing

along the optic nerve and enucleation is often

pigmented and nonpigmented portions of melanoma in same

life saving. Until recently, enucleation was the

eye (with acknowledgement to Mr A. Foss).

treatment of choice and cure rates of 90-95%

were achieved. Nowadays, eye-sparing therapy

laser photocoagulation for small lesions, local

is preferred, in an attempt at avoiding the

resection and transpupillary thermotherapy.

physical and psychological trauma involved in

Untreated, the tumour can extend into the

enucleating a young child. Alternative treat-

orbit and provide an unpleasant problem for

ment options include initial systemic tumour

the patient.

chemoreduction with carboplatin-based regi-

mens, followed by external beam radiotherapy,

Choroidal Metastases

plaque radiotherapy, cryotherapy or laser pho-

tocoagulation. Genetic counselling is essential

These make up the most common intraocular

for these patients in order to prevent the

tumours in adults. Although lesions can be

increasing incidence of the tumours, which will

demonstrated in at least 1-2.5% of patients with

result from effective medical treatment.

carcinomas, many cases remain asymptomatic

unless the macula is involved. In males, the most

Melanoma of the Iris

common primary tumour is found in the lung

and in females, it is the breast. The metastatic

This rare iris tumour usually presents as a sol-

tumours are usually treated with external

itary iris nodule, which might or might not be

beam radiotherapy.

pigmented. It can cause distortion of the pupil,

which can be an early warning sign. Other fea-

tures that can point to the diagnosis are local-

Retinoblastoma

ised lens opacity, iris neovascularisation and

This is a rare tumour of childhood, which arises

elevation of intraocular pressure. Melanoma of

not from the choroid but, as its name suggests,

the iris is extremely slow growing and probably

from the retina. It is, however, the commonest

much less malignant than choroidal melanoma,

Tumours of the Eye and Adnexae

123

Molluscum Contagiosum

This is caused by a viral infection and is most

commonly seen in children. The lesions consist

of several pale, waxy, umbilicated nodules on the

eyelids and face. Similar lesions can be located

on the trunk. The eyelid lesions shed viral par-

ticles, which produce a chronic conjunctivitis

and less often superficial keratitis. The lesions

might disappear in about six months, but can

need curettage or cautery.

Papilloma

Figure 15.2. Retinoblastoma: leucocoria.

This is the name used to describe a rather

common virus-induced nodule or filiform wart

often seen on the lid margin.

with a survival rate of at least 95% at five years.

Treatment is usually in the form of a sector or

Seborrhoeic Keratosis

total iridectomy.

This is common in the elderly and consists

of slow-growing, sessile, greasy lesions of the

The Eyelids

eyelid. They are usually brown and friable.

Benign Tumours

Senile Keratosis

Meibomian Cysts (Chalazion)

Senile keratosis consists of multiple, flat, scaly

This is the commonest eyelid lump in all ages.

lesions, which can occasionally undergo trans-

It is caused by blockage of the meibomian gland

formation into a squamous cell carcinoma.

orifice such that the secretions accumulate. A

granulomatous inflammation is set up, which

Xanthelasma

results in a painless, round, firm, slowly growing

lump in the tarsal plate (Figure 15.3).The cyst can

These are slightly elevated lesions consisting of

become infected, when it becomes red hot and

lipid deposits usually on the medial aspect of

painful. Treatment is by incision and curettage.

the eyelids. They can be associated with hyper-

lipidaemia, especially in the younger patient.

Keratoacanthoma

This is an example of a lesion that grows rapidly,

too rapidly for a neoplasm, over a period of

a few weeks and then resolves spontaneously

(Figure 15.4). It usually starts as a red papule,

which grows quickly into a nodule with a

keratin-filled crater. The lesion can resemble a

basal cell carcinoma. Small lumps on the eyelids

should be removed and biopsied. Larger lumps

can be biopsied by taking a small segment from

them before total excision if this proves neces-

sary. Special care should be taken with the exci-

sion of any lesion on the eyelid in view of the

risk of causing distortion of the lid margin or

Figure 15.3. Chalazion.

exposure keratitis.

124

Common Eye Diseases and their Management

Cavernous Haemangioma

These tumours lie more deeply in the skin and

appear as a bluish swelling in the lid, which

expands when the child cries. These lesions can

also disappear spontaneously or, if persistent,

they can be treated by freezing.

Telangiectatic Haemangioma

Also known as the port wine stain or naevus

flammeus, this tumour tends to be distributed

over the area supplied by one or more of the

branches of the fifth cranial nerve and usually

Figure

15.4. Keratoacanthoma

(with acknowledgement to

remains throughout life as a dark red dis-

Mr A. Sadiq).

colouration in the skin

(Figure

15.5). The

importance of this particular appearance is its

association with secondary glaucoma and hae-

Kaposi Sarcoma

mangioma of the meninges. The latter produces

This is a well-known association with acquired

calcification and a characteristic X-ray appear-

immune deficiency syndrome

(AIDS). The

ance. The combination of lesions is known as

lesions consist of purple nodules on the eyelid

the Sturge-Weber syndrome. There can be

and similar lesions in the lower conjunctival

hypertrophy of the affected area of the face,

fornix composed of proliferating endothelial

leading to asymmetry.

and spindle-shaped cells. Inflammatory cells

might also be present with vascular channels

Malignant Tumours of the Eyelids

without endothelial cell lining. Human herpes

virus 8 is thought to be important in the patho-

Basal Cell Carcinoma

genesis of these lesions.

This is the most common malignant tumour of

the eyelid in adults (80-90% of cases). Patho-

Benign Vascular Tumours of

the Eyelids

These fall into three types: capillary haeman-

gioma of the newborn (strawberry naevus),

cavernous haemangioma and telangiectatic

haemangioma.

Capillary Haemangioma of the Newborn

(Strawberry Naevus)

This is usually seen before the age of six months,

and nearly all examples regress spontaneously,

usually in few months and by the age of five years.

Tumours appear as red, slightly raised marks on

the skin. Even extensive tumours of this kind can

show a dramatic improvement over several years

and conservative management is usually indi-

cated unless the tumour is associated with a fold

of skin that occludes the eye, causing amblyopia.

Larger tumours can produce orbital enlarge-

ment. If treatment is required, intralesional

steroid injections have proved beneficial.

Figure 15.5. Port wine stain (naevus flammeus).

Tumours of the Eye and Adnexae

125

genesis is related to exposure to ultraviolet light,

hence it most frequently involves the lower

lid and medial canthus. The tumour begins as a

small insignificant nodule, which turns into a

small crater-like lesion with a slightly raised,

pearly-coloured edge with fine dilated blood

vessels on its surface (Figure 15.6). Although the

tumour rarely metastasises, it is locally invasive,

and, therefore, early diagnosis and treatment is

important. In the early stages, it is a simple

matter to remove the lesion and confirm the

diagnosis by biopsy, but if left the tumour tends

to spread into surrounding structures and into

the underlying bone and orbit (Figure 15.7).

Treatment depends on the size, extent and loca-

tion of the tumour. Usually, surgical excision

with wide margins is the technique of choice,

either by a simple excisional biopsy or by the

more complex Mohs’ procedure. The more

extensive, neglected basal cell carcinomata

are treated by radical surgery, cryotherapy or

palliative radiotherapy.

Squamous Cell Carcinoma

Squamous cell carcinoma is the second most

Figure 15.7.

Extensive basal cell carcinoma involving the orbit

common malignant eyelid lesion and cons-

and extending across the nose to the opposite side. a Clinical

titutes 5-10% of cases. It occurs most commonly

photograph; b computerised tomography scan.

in the elderly and is related to sunlight exp-

osure. The tumour can initially resemble a basal

cell carcinoma, although the edges are usually

not rolled. Spread tends to occur to the local

lymph nodes (preauricular for the upper lid and

submandibular for the lower lid). Treatment is

similar to a basal cell carcinoma.

Sebaceous Gland Carcinoma

This uncommon tumour constitutes 1-3% of

malignant eyelid tumours (higher in Asians). It

arises from the meibomian glands in the tarsal

plate. It appears as a discrete, firm nodule, which

often presents as a “recurrent chalazion”, thereby

delaying diagnosis. Treatment involves wide

excision with or without radiotherapy. Mortality

ranges from 6% to 30%, depending on site, size,

symptom duration and histological classification.

Melanoma of the Eyelid

Malignant melanoma of the eyelids is similar to

malignant melanoma elsewhere, appearing as a

raised, often shiny, black lump. It metastasises at

an early stage and the prognosis does not seem

to be altered by excision.

Figure 15.6. Early basal cell carcinoma of medial canthus.

126

Common Eye Diseases and their Management

The Conjunctiva

Benign Lesions

Benign Pigmented Lesions of

the Conjunctiva

Conjunctival epithelial melanosis occurs in

approximately 90% of black people and 10%

of white people, and is noticeable in early life.

The lesions are flat, brownish patches scattered

throughout the conjunctiva, but might be more

noticeable at the limbus (Figure 15.8). Usually,

they do not grow. Other pigmented lesions,

Figure 15.9. Pterygium.

for example the benign naevus, require closer

attention and specialist evaluation.

Malignant Lesions

Nonpigmented Lesions

Melanoma of the Conjunctiva

Pingueculum is a common mass lesion of the

Malignant melanomata can occur on the

conjunctiva. It is seen as a yellowish nodule

conjunctiva

(Figure

15.10) but they should

usually on the medial interpalpebral fissure. It is

not be confused with the relatively common

a fibrovascular degeneration and is seen in

benign conjunctival naevus. The latter is a

all climates.

slightly raised pigment-stippled lesion often

Pterygium is a growth of abnormal fibrovas-

seen at the limbus on the temporal side. Closer

cular tissue extending from the conjunctiva over

examination with the hand lens or microscope

the cornea (Figure 15.9). It is thought to result

reveals one or two minute cysts. It is generally

from to chronic irritation from dust and solar

accepted that these benign lesions should be

radiation. It is more common in hot climates

excised and biopsied if they become irritable or

and individuals who work out of doors. Recur-

sometimes simply on cosmetic grounds, but

rent inflammation of the pterygium is often

they rarely become malignant. The treatment of

self-limiting but responds to a short course of

conjunctival malignant melanoma involves

topical steroids. If it extends over the visual axis

wide surgical excision with adjuvant cryother-

of the cornea it can cause visual impairment

apy or radiotherapy. The five-year survival rate

and, therefore, surgical excision might be

is approximately 85%.

required, although regrowth occurs in a large

proportion of patients.

Figure 15.8. Conjunctival melanosis.

Figure 15.10. Melanoma of conjunctiva.

Tumours of the Eye and Adnexae

127

surgical resection and/or radiotherapy is indi-

The Orbit (see Table 15.1)

cated if intracranial spread is documented.

Lacrimal Gland and Sac Tumours

Rhabdomyosarcoma

Lacrimal gland tumours can either be inflam-

matory, mixed cell tumours or adenocarcino-

This rare but highly malignant orbital tumour

mas. They present with proptosis or a mass in

is seen in children. Its growth is so rapid that it

the outer part of the eyelid superotemporal

may be misdiagnosed as orbital cellulitis. If a

orbit. Lacrimal sac tumours are less common

correct diagnosis is made at an early stage, there

and present with sac swelling. Benign lesions

is some hope of reaching a cure by combining

and infections need to be excluded.

radiotherapy and chemotherapy. The tumour is

thought to arise from striated muscle and the

histological diagnosis is confirmed by finding

Dermoid Cyst

striation in the tumour cells. It is usually located

This cystic swelling is usually seen at the level of

in the superonasal orbit.

the eyebrow in the upper outer part of the orbit.

It is smooth and fluctuant and often fixed to bone.

Metastatic Tumours and Tumours

Sometimes a deeper part of the cyst can occupy

from Neighbouring Sites

a cavity in the bone and a computed tomography

(CT) scan is advisable when this is suspected.

A wide variety of tumours can invade the orbit

Rupture of the cyst can lead to profound orbital

and produce proptosis and often diplopia. Lym-

inflammation. Excision on cosmetic grounds and

phoma is one example. It can present as an iso-

for diagnosis is usually indicated.

lated lesion or in association with Hodgkin’s

disease or leukaemia. Examples of local spread

Cavernous Haemangioma

from adjacent structures include carcinoma

of the nasopharynx, carcinoma of the lacrimal

This is the commonest primary neoplasm of

gland and meningioma. In children, orbital

the orbit in adults. It is benign. It is unusual

metastases arise most commonly from neuro-

for surgery to be necessary in such cases. It is

blastoma and Ewing’s sarcoma. In the adult, the

usually located within the muscle cone, and

commonest primary sites are bronchus, breast,

gives rise to axial proptosis.

prostate and kidneys.

Glioma of the Optic Nerve

“Pseudotumour” (Idiopathic Orbital

Inflammatory Disease)

This rare tumour causes progressive proptosis

and optic atrophy but it can be slow growing.

This is an inflammatory swelling in the orbit of

There is an association with Von Reckling-

unknown cause, which can present with pain,

hausen’s disease

(neurofibromatosis type

proptosis and diplopia. A mass might be palpa-

and the presence of pigmented patches in the

ble in the orbit and biopsy reveals nonspecific

skin should make one suspect this. Treatment by

inflammatory tissue consisting mainly of lym-

phocytes. Diagnosis can eventually be made

Table 15.1. Primary orbital tumours.

by exclusion of other causes of proptosis. In

severe cases, a course of systemic steroids

Vascular

Capillary haemangioma

Cavernous haemangioma

and/or radiotherapy is usually effective.

Lymphangioma

Neural

Optic nerve glioma

Meningioma

Exophthalmos and Proptosis

Neurofibromatoma

Lacrimal gland

Both these terms mean forward protrusion of

Lymphoproliferative

the eyes but traditionally exophthalmos refers

Rhabdomyosarcoma

to the bilateral globe protrusion in thyroid

Histiocytosis

disease. Proptosis refers to unilateral forward

128

Common Eye Diseases and their Management

displacement of the globe from whatever cause.

In practice, the terms tend to be used rather

loosely and are now almost synonymous.

Causes of Proptosis (see Table 15.2)

When one eye seems to bulge forward, the

doctor might have a serious problem on his

hands and the following likely causes should be

considered:

•

Pseudoproptosis. An apparent bulging

forward of the eye occurs if the eye is too

big, as in unilateral high myopia, or if the

other eye is sunken following a blow-out

fracture of the maxilla

(orbital floor).

These need to be distinguished from a

true proptosis.

•

Thyrotoxicosis. This is the commonest

cause of unilateral or bilateral proptosis;

diagnosis is achieved from the history,

Figure 15.11.

Proptosis: dysthyroid disease.

examination and tests of thyroid function

(Figure 15.11).

•

Infection. Orbital cellulitis, usually from

neighbouring sinuses, requires urgent

•

Others. There are a large number of pos-

otorhinological opinion.

sible but rare causes of proptosis.

•

Trauma. Proptosis can occur as a result

of retro-orbital haemorrhage. Diagnosis

Assessment of Proptosis

should be possible from the patient’s history.

•

Haemangioma. This can expand after

In the clinic, proptosis is best assessed by stand-

bending down or crying.Ultrasound and CT

ing behind the seated patient and asking him to

scanning can confirm the diagnosis. Occa-

look down. The position of each globe in rel-

sionally, angiography might be required.

ation to the lids and face can be best seen by this

means. Proptosis can be measured by means

•

Pseudotumour. Biopsy should be carried

of an exophthalmometer. A number of such

out if possible, and other causes excluded.

instruments are on the market and they depend

•

Mucocele of sinuses. Diagnose by X-ray or

on measuring the distance from the rim of the

CT scan.

outer margin of the orbit to the level of the

•

Lymphoproliferative disease. A biopsy, full

anterior part of the cornea. These measure-

blood count and sternal marrow puncture

ments are not always accurate (especially for

should be carried out.

the novice) but best results are achieved by

ensuring that they are made by the same person,

using the same instrument on each occasion for

a given patient.

Once thyroid disease and trauma have been

Table 15.2. Causes of proptosis.

excluded, the patient would require further

•

Endocrine

investigations including systemic examination,

•

Vascular abnormalities

full blood picture, orbital ultrasound, CT scan,

•

Inflammatory disorders

magnetic resonance imaging

(MRI) scan,

•

Primary orbital tumours

possibly carotid angiography and sometimes

•

Metastases

orbital biopsy.

Ocular Trauma

The fact that injuries to the eye and its sur-

control are the use of protective guards in ice

rounding region demand special attention and

hockey and cricket. The surrounding orbital

create great concern for patient and doctor is

margin provides good protection to the eyes

self-evident when the eye alone is involved, but

from footballs and even tennis and cricket balls,

when other life-threatening injuries are present,

but the rare golf ball contusion injury usually

the eye injury, seeming slight at the time, might

leads to loss of the sight of the eye. Squash balls

be overlooked. Sometimes, the eyelids might be

and especially shuttle cocks have earned a bad

so swollen that it is difficult to examine the

reputation for inflicting contusion injuries and,

eyes and a serious perforating injury could be

from the economic point of view, leading to loss

obscured. When other injuries are present and

of time at work and hospital expenses.

an anaesthetic is needed, it is essential that the

The extent of damage to the eye from con-

eyes are examined carefully, if possible under

tusion depends on whether it has been possible

the same anaesthetic. As in the case of injuries

to close the eyelids in time before the moment

elsewhere, those to the eye demand urgent and

of impact. If the lids have been closed, bruising

immediate treatment, and neglect can result in

and swelling of the eyelids is marked and the

tragedy even though the problem might have at

injury to the eye might be minimal. It must be

first seemed slight.

remembered though that this is not an infallible

rule and the eyes themselves must always be

carefully examined, even when there is extreme

swelling of the lids. It is always possible to

Injuries to the Globe

examine an eye, if necessary using an eye spec-

ulum under general anaesthesia. In the primary

Contusion

care situation, one must be very careful not to

The eye casualty officer comes to recognise a

apply more than gentle pressure to the eyelids

familiar pattern of contusion, the effect of

in case the globe of the eye has been perforated

squash ball injuries and blows from flying

and when there is doubt, referral to the eye

objects in industry or after criminal assault.

department is advisable. The important clinical

Injuries from industrial causes have now

features of contusion injury are best considered

become quite uncommon thanks to better

by looking at the anatomical parts of the eye.

control by means of protective clothing and

proper guarding of machinery.As a result, sport-

Cornea

ing injuries have become more evident, although

here increasing public concern has also led to

The most common injury to the cornea is from

some improvement. Notable instances of good

the corneal foreign body and this has already

129

130

Common Eye Diseases and their Management

been described in Chapter 5.Almost as common

is the corneal abrasion. It is odd how this is so

often caused by the edge of a newspaper, a comb

or a child’s fingernail. Abrasions from the leaves

of plants or twigs need special attention because

of the type of infection that can occur (fungal),

but any abrasion can lead to the condition

known as recurrent abrasion. Here, the patient

experiences a sharp pain in the eye in the early

morning usually on waking, sometimes many

months after the initial injury. It is thought that

the lid margin adheres to the area of weakened

healed corneal epithelium during sleep. The

diagnosis is easily missed if the patient has

Figure 16.1. Hyphaema showing anterior chamber half filled

forgotten about the original injury and if the

with blood.

cornea is not examined carefully with the slit-

lamp biomicroscope. This problem of recurrence

temporal part of the eye and it is in this region

is a reason to treat these abrasions with some

of the iris that one is most likely to see periph-

care and to provide the patient with a lubricat-

eral iris tears (“iridodialysis”).

ing ointment to be used at night for some time

When the eye is compressed the iris periph-

after the original injury has healed. Sometimes,

ery is torn at its root, leaving a crescentic gap,

recurrent abrasion results from a rare inherited

which looks black, but through which the

disorder of the corneal epithelium.

fundus and red reflex can be observed. Such an

When a patient presents with a corneal abra-

injury also provides an excellent view of the

sion, the eyelids are often swollen perhaps from

peripheral part of the lens and the zonular lig-

rubbing and the distress and agitation can be

ament (Figure 16.2).

considerable. Examination may be impossible

Contusion can result not in a tear of the iris

without first instilling a drop of local anaes-

root, but in a tangential splitting of the iris and

thetic. These drops should never be continued

ciliary body from the sclera producing recession

as treatment because they could seriously delay

of the angle of the anterior chamber; the

the healing of the cornea.

appearance is often associated with secondary

glaucoma, sometimes many years after the

Anterior Chamber

injury and is identified using the special contact

lens known as the gonioscope.

A small bleed into the anterior chamber of the

A sudden impact on the eye can also pro-

eye is seen as a fluid level of blood inferiorly

duce microscopic radial tears in the pupillary

(“hyphaema”) (Figure 16.1). This is a sign of

potential problems because of the risk of sec-

ondary bleeding after two or three days. This

risk is especially serious in children and the

complication can lead to secondary glaucoma

and at worst, the loss of the eye. The parents need

to be warned about this if there is a hyphaema.

Treatment is by strict rest with little or no head

movement to avoid further bleeding and regular

measurement of the intraocular pressure.

Iris

When confronted by a flying missile, the normal

reaction is to attempt to close the eyelids and to

rotate the eyes upward. This is the reason why

Figure 16.2. Iridodialysis or splitting of the iris root in lower

the commonest point of impact is the lower

temporal quadrant. A sure sign of previous contusion.

Ocular Trauma

131

sphincter of the iris. This could be a subtle

Choroid

microscopic sign of previous injury when no

Tears in the choroid following contusion have a

other signs are present, or the damage might

characteristic appearance. They are concentric

be more severe, resulting in persistent dilatation

with the disc and are seen as white crescents

of the pupil (traumatic mydriasis). Unless the

where the sclera is exposed. When near the

eye is examined, this widening of the pupil

macula, there is usually permanent damage to

after injury can be mistaken for a third cranial

the central vision (Figure 16.3). They are also

nerve palsy.

potential sites for choroidal neovascularisation.

Lens

Optic Nerve

Any severe contusion of the eye is liable to cause

A variable degree of optic atrophy can become

cataract, but the lens might not become opaque

apparent a few weeks after a contusion injury.

for many years after the injury. The lens can

Blunt injuries to the eye can cause bleeding into

also become subluxated

(slightly displaced

the optic nerve sheath or tearing of the tiny pial

because of partial rupture of the zonular liga-

blood vessels that supply the nerve, both result-

ment) or even dislocated either anteriorly into the

ing in complete, irreversible loss of vision on

anterior chamber or posteriorly into the vitreous.

the affected side. Attempts have been made to

relieve the situation by emergency decompres-

sion of the optic nerve, nerve sheath fenestra-

Vitreous

tion, use of hyperbaric oxygen and high-

The vitreous can become displaced from its

dose steroids. No treatment has shown a clear

attachments around the processes of the ciliary

benefit except optic nerve decompression in

body or around the optic disc after a contusion

specific circumstances.

injury if it has not already undergone this

change as part of the normal ageing process.

Perforation

The patient might be aware of something

floating in front of the vision. More extensive

As soon as the globe of the eye is penetrated

floating black spots can indicate a vitreous

there is a serious risk of infection. The vitreous

haemorrhage caused by excessive vitreous trac-

is an excellent culture medium and in the

tion on a retinal blood vessel. Although such

haemorrhages usually clear completely in time,

they tend to accompany more serious damage to

the retina, which can only be fully revealed once

clearing has taken place.

Retina

Bruising and oedema of the retina are seen as

grey areas with scattered haemorrhages. The

macular region is susceptible to oedema after

contusion injuries, causing permanent damage

to the reading vision. Just as tears can occur to

the peripheral iris, so a similar problem is seen

in the peripheral retina. These crescent-shaped

retinal dialyses are also most common in the

lower temporal quadrant and their importance

lies in the fact that they may lead to a detach-

ment of the retina unless the tear is sealed by

laser treatment. Any significant contusion

injury of the eye requires a careful inspection of

Figure 16.3. Healed choroidal tear. Another sign of previous

the peripheral retina.

injury.

132

Common Eye Diseases and their Management

pre-antibiotic era, eyes were totally lost within

two or three days as a result of this. A perforat-

ing wound of the eye must, therefore, be consi-

dered a surgical emergency. Perforating injuries

are seen in children from scissor blades, screw-

drivers, darts and other more bizarre objects. In

adults, there has been a dramatic fall in the inci-

dence of such injuries since the introduction of

compulsory seat belts but “do-it-yourself ” acci-

dents and assaults still take their toll. Following

such an injury it is important to consider the

possibility of an intraocular foreign body, espe-

cially when there is a history of using a hammer

and chisel.

Figure

16.4. A small metallic foreign body lying on the

The outcome of a perforating injury is

retina.

dependent on the depth of penetration and the

care with which the wound is cleaned and

sutured. If the cornea alone is damaged, excel-

reous forceps under microscopic control or

lent results can be obtained by careful suturing

using a magnet. The exact surgical technique is

under general anaesthesia using the operating

planned beforehand once the foreign body has

microscope. If the lens has been damaged, early

been accurately localised in the eye. Airgun

cataract surgery might be needed and deeper

pellets cause particularly severe eye injuries and

penetration can result in the need for retinal

the eye is often lost because of the extensive dis-

detachment surgery.

ruption at the time of the injury. Some intraoc-

On admission or in the casualty department,

ular foreign bodies, such as glass particles or

the patient is given tetanus prophylaxis and

some alloys, might be tolerated quite well and a

both systemic and local antibiotics. If early

decision could have to be made as to whether

surgery under general anaesthesia is likely to be

observation is preferable in the first instance.

needed, it is better for the patient not to eat or

This especially applies when the sight of the eye

drink to avoid delays in hospital. If it becomes

remains good. When a foreign body is not to be

clear that the injury is a serious one, it is better

removed immediately, many ophthalmologists

to warn the patient at an early stage about the

would insert intravitreal antibiotics as a pro-

possible risk of losing the sight of the eye or

phylactic measure against endophthalmitis.

even the need to replace it with an artificial one.

When a foreign body is found lying deeply in

the cornea, its removal can result in loss of

aqueous and collapse of the anterior chamber.

Intraocular Foreign Body

It is prudent to arrange that removal should be

Metallic foreign bodies tend to enter the eyes of

done under full sterile conditions in the operat-

those who operate high-speed grinders without

ing theatre, where the corneal wound can be

goggles or those using a hammer and chisel on

sutured if necessary.

metal without eye protection. These injuries

might seem slight at first and sometimes

Sympathetic Ophthalmia

patients do not attach much importance to

them.Any such eye injury with this occupational

This rare complication of perforation is more

history warrants an X-ray of the eye. When

common in children. The injured eye remains

ferrous metals remain in the eye they can cause

markedly inflamed and the wound might have

immediate infection, or at a later date the depo-

been cleaned inadequately or too late. Over a

sition of ferrous salts, in a process known as

period of two weeks to several months or even

siderosis. This can eventually lead to blindness

years a particular type of inflammatory

of the eye. Other metals also tend to give reac-

response begins in the uvea and subsequently a

tions, particularly copper and for this reason the

similar reaction occurs in the other eye. The

metallic fragment should be removed (Figure

inflammation in both eyes can be so severe as to

16.4). This is achieved either by using intravit-

cause blindness. The condition does, however,

Ocular Trauma

133

respond well to steroid treatment and it is

paid when the medial part of the eyelid has been

extremely rare. Occasionally, one sees patients

torn, as this contains the lacrimal canaliculus.

who have an artificial eye complaining of tran-

Again, unless repair is carried out using an

sient blurring of the vision of their remaining

accurate technique under general anaesthesia in

eye. They need to be examined carefully for

theatre, the risk of a permanently watering eye

signs of uveitis.

is increased.

Contusion of the eyelids, otherwise known as

a black eye, is of course a common problem,

Injuries to the Eyelids

especially on Saturday nights in a general cas-

ualty department. Usually, the presence of a

Loss or destruction of eyelid tissue should

black eye is an indication that the afflicted was

always be treated as a threat to vision. The upper

smart enough to close his eye in time to avoid

lid especially is important in this respect. The

injury to the globe. It is unusual to find damage

immediate concern is to ensure that the cornea

to the eyes after Saturday night fist-fights, unless

is properly covered when the eyelids are closed.

a weapon was involved. Broken beer glasses

If more than one-third of the margin of the

produce devastating injuries to the eyes as well

upper lid is lost, this must be replaced by graft-

as to the eyelids.

ing from the lower lid. When less than one-third

is missing, the gaping wound can usually be

closed directly. Up to one-third of the lower lid

Injuries to the Orbit

can also be closed by direct suturing. When

more than this is lost or when it has been trans-

Blows on the side of the cheek and across one

ferred to the upper lid, a slide of tissue from the

or other eye occur in fights, industrial accidents

lateral canthus can be effected, combined if nec-

and road traffic accidents. The most common

essary with a rotating cheek flap.

type is the “blow-out fracture”. Here the globe

One of the most important features of the

and contents of the orbit are forced backwards,

repair of lid injuries is the method of suturing.

causing fracture of the orbital floor and dis-

If the lid margin is involved, the repair should

placement of bone downwards into the antrum

be made using the operating microscope and

of the maxillary sinus. The inferior rectus

the fine suture material available in an eye

muscle becomes tethered in the wound so that

department (Figure 16.5). An untidy repair can

there is mechanical limitation of upward move-

result in a permanently watering eye because of

ment. The infraorbital nerve, which traverses

kinking of the eyelid. This interferes with the

the orbital floor, can also be injured, producing

proper moistening of the cornea during blink-

anaesthesia of the skin of the cheek. Once the

ing or when asleep. Special attention must be

surrounding swelling has subsided, the post-

erior displacement of the globe becomes

obvious and the globe of the eye itself often

shows evidence of contusion. A considerable

improvement from the functional and cosmetic

point of view can be obtained by positioning a

plastic or Teflon implant in the floor of the orbit

after freeing the prolapsed tissue.

Fractures of the skull that extend into the orbit

can be accompanied by retro-orbital haemor-

rhage and proptosis. Cranial nerve palsies affect-

ing the ocular movements are also commonly

seen in this type of injury and the vision can be

affected by optic nerve damage.A blow on the eye

can result in sudden blindness with at first no

other evidence of injury (apart from an afferent

pupillary defect), but subsequently, the optic

disc becomes pale and atrophic after two or

Figure 16.5. Full thickness lower lid laceration.

three weeks.

134

Common Eye Diseases and their Management

effect, the symptoms appearing 2 h or 3 h after

Radiational Injuries

exposure and lasting for about 48 h. There is

usually severe pain and photophobia so that

The eyes might be exposed to a wide range of

it might not be possible to open the eyes,

electromagnetic radiation from the shorter

hence the term “snow blindness”. The use of

wavelength ultraviolet rays through the wave-

locally applied steroid and antibiotic drops

lengths of visible light to the longer infrared

hastens recovery.

waves, X-rays and microwaves. X-rays pass

Unlike ultraviolet light, infrared rays pene-

straight through the eye without being focused

trate the eye and can cause cataract. A specific

by the optical media and, in large enough doses,

kind of thermal cataract has been well des-

can cause generalised damage. It is important to

cribed in glass-blowers and furnace workers

realise that therapeutic but not diagnostic doses

but this is now rarely seen because of the use of

of X-rays tend to cause cataracts and the eye

protective goggles. Microwaves, in the form of

must be suitably screened during treatment.

diathermy, can cause cataract but the eye must

Excessive doses of X-rays also cause stenosis of

be in the path of the beam if damage is to occur,

the lacrimal canaliculi, destruction of the secre-

and microwave ovens would not be expected to

tory cells within the lacrimal glands and retinal

be dangerous in this respect. Concern is quite

neovascularisation. As one might expect, visible

often expressed in the press or elsewhere about

light does not normally damage the eyes,

the possibility of radiation damage to the eyes

although an intense light source can be absorbed

from visual display units. Such damage has

by the pigment epithelium behind the retina and

never been demonstrated any more than it has

converted to heat, producing a macular burn.

from the face of a television set. Someone not

After eclipses of the sun, there are usually a

used to working with a visual display unit who

number of patients who arrive in the casualty

is suddenly made to spend several hours a day

departments of eye hospitals with macular

in front of one might experience eyestrain, esp-

oedema and sometimes serious permanent

ecially if incorrect spectacles are worn.

impairment of visual acuity. Sun gazing, with

consequent retinal damage, has been reported

after taking lysergic acid diethylamide (LSD).

The laser beam provides a source of intense

light, which is used widely in ophthalmology as

Chemical Injuries

a deliberate means of producing gentle burns in

the retina or making holes in the lens capsule

These are quite common but usually not severe

after cataract surgery. However, uncontrolled

enough to warrant hospital attention. In indus-

use of lasers can cause blinding foveal burns as

trial premises there is now nearly always a first-

the subject tends to look directly at the beam

aid post with facilities to wash out the eyes.

momentarily, until they realise what it is. Ultra-

Plain water or a salt solution is the best fluid to

violet rays, which are shorter than visible light,

use and valuable time may be lost if washing is

do not normally penetrate the eye but in large

delayed in order to search for a specific antidote.

enough doses produce burns of the eyelids and

More severe burns can result from the catalysts

cornea. On the skin this is seen as erythaema

used in the manufacture of plastics or from

and later pigmentation, and on the cornea a

alkalis, such as caustic soda. Alkalis penetrate

punctate keratitis is seen with the slit-lamp.

the eye rapidly as they saponify lipids within

Ultraviolet damage of this kind is seen after

cell membranes, aiding passage, and can quickly

gazing with unprotected eyes at welder’s arcs,

reach the posterior segment. Acid burns as from

after exposure of the eyes to sunray lamps, and

exploding car batteries are quite commonly

after exposure to the sun under certain condi-

seen in large casualty departments but are

tions such as in snow on mountain tops. All

usually less severe as acids tend to coagulate

these types of ultraviolet injury show a delayed

corneal proteins, thereby slowing penetration.

Testing Visual Acuity

Measurement of visual acuity is the most

appears to be blind, being unable to find his way

important part of the ocular assessment per-

about, but he might surprise the ophthalmolo-

formed by the doctor and yet it is surprising

gist by reading the visual acuity chart from top

how often the nonspecialist omits it in exam-

to bottom once he has found it.

ination. It has already been shown that the

The simplest way to measure visual acuity

differential diagnosis of the red eye can be

might be to determine the ability to distinguish

simplified by noting the vision in the affected

two points when placed close together (resolu-

eye. After injuries of the eye, it is just as impor-

tion). Such a method was supposed to have been

tant to note the vision in the uninjured eye as in

used by the Arabs when choosing their horse-

the injured eye. Simple measurement of visual

men. They chose only those who were able to

acuity is of limited value without a knowledge

resolve the two stars that form the second “star”

of the spectacle correction or whether the

in the tail of the Great Bear constellation. A

patient is wearing the appropriate spectacles.

point source of light such as a star, although it

The best corrected visual acuity (i.e., with lenses

is infinitely small, forms an image with a diam-

in place) therefore needs to be recorded for each

eter of about 11mm on the retina. This is because

eye. This corrected visual acuity can also be est-

the optical media are not perfect and allow

imated with a pinhole held in front of the eye.

some scattering of the light. In practice, it is pos-

The effect of the pinhole is to eliminate the

sible for a person with normal vision to distin-

effect of refraction by the cornea and the lens

guish two points if they are separated by

on the extremely thin beam of light produced by

1 mm when placed 10 m away. Two such points

the pinhole.

would be separated by 2 mm on the retina. This

Measuring the visual acuity means measuring

might be surprising considering that a spot of

the function of the macula, which is of course

light casts a minimum size of image of 11 mm

only a small part of the whole retina. A patient

because of scatter, but such an image is not

might have grossly impaired visual acuity and

uniform, being brighter in the centre than at the

yet have a normal visual field, enabling him to

periphery. In fact, the resolving power of the eye

walk about and lead a normal life apart from

is limited by the size of the cones, which have a

being unable to read.This state of affairs is seen

diameter of 1.5 mm.

in patients with age-related macular degenera-

In the clinic, the distance visual acuity is

tion and can be compared with the situation in

measured by asking the patient to read a stan-

which a patient has grossly constricted visual

dard set of letters, the Snellen chart. This is

fields but normal macular function, as is some-

placed at a distance of 6 m from the eye. The

times seen in retinitis pigmentosa or advanced

single large letter at the top of this chart is

primary open-angle glaucoma. Here, the patient

designed to be just discernible to a normal-

137

138

Common Eye Diseases and their Management

sighted person at a range of 60 m. If the patient’s

vision is so poor that only this and no smaller

letter can be seen at 6 m, the vision is recorded

as the fraction

“6/60”. The normal-sighted

person who can read the chart down to the

smaller letters designed to be discerned at 6 m

is recorded as having a visual acuity of 6/6. The

normal range of vision extends between 6/4 and

6/9, depending on the patient’s age. In some

European countries, the visual acuity is

expressed as a decimal instead of a fraction.

Therefore, 6/60 would be expressed as 0.1. In the

USA, metres are replaced by feet, so 6/6 becomes

20/20. This is where the term “twenty twenty”

vision originates from, meaning clear or near-

perfect vision. Recently, a new type of visual

acuity chart has entered use in the clinic and in

research studies. It is called the LogMAR chart

and differs from the conventional Snellen chart

(Figure 3.1) by having five letters on each line

The newsprint these days isn’t what

rather than the “pyramid” shape of the Snellen

it used to be

chart. There are also smaller differences in type

Figure 17.1.

Reading glasses in presbyopia.

size between lines. Some of the advantages of

using this new chart are that the measurement

of poor visual acuity is more accurate as more

larger letters are included and small changes

in acuity are easier to detect (easier to detect

disease progression or treatment success).

shown to the child, who is asked to point to the

The near visual acuity is also measured using

same letter on the card, which is given to him.

a standard range of reading types in the style of

Up to the age of 18 months or two years, the

newsprint and, here, care must be taken to

optokinetic drum might be used. This makes

ensure that the correct spectacles for near work

use of the phenomenon of optokinetic nystag-

are used if the patient is over the age of 45 years

mus produced by moving a set of vertically

(Figure 17.1). Normally, the results of testing the

arranged stripes across the line of sight. When

near visual acuity are in agreement with those

the stripes are sufficiently narrow, they are no

for measuring distance vision providing the

longer visible and fail to produce any nystag-

correct spectacles are worn if needed.

mus. The eyes are examined using a graded

The visual acuity of each eye must always be

series of stripes. This kind of test can be used to

measured by placing a card carefully over one

measure visual acuity in animals other than

eye and then transferring this to the other eye

man. The “E” test is a way of measuring the

when the first eye has been tested. The visual

visual acuity of illiterate patients. This is based

acuity of both eyes together is usually the same

on the Snellen type but the patient is presented

or fractionally better than the vision of the

with a series of letter “E”s of different sizes and

better of the two eyes tested individually. In

orientations and is given a wooden letter “E” to

certain special circumstances, the binocular

hold in the hands. He is then instructed to turn

vision can be worse than the vision of each

the wooden letter to correspond with the letter

eye tested separately (e.g., in cases of macular

indicated on the chart.

disease causing distortion).

The Snellen type has the great advantage of

A number of other tests have been developed

being widely used and well standardised, but it

to measure visual acuity in the nonliterate

must be realised that it is a measure of some-

patient. Infants below the reading age can be

thing more complex than simply the function

measured with surprising accuracy using the

of the macula area of the retina. It involves a

Stycar test. Here, letters of differing size are

degree of literacy and also speech, and testing

Testing Visual Acuity

139

shy children or elderly patients can sometimes

both objective and subjective refractions are

be misleading.

performed and the results compared.

Other ways of measuring visual acuity have

been developed. One is to assess the patient’s

Objective Refraction

ability to resolve a grating. Here, the word

“grating” refers to a row of black-and-white

The patient is fitted with a spectacle trial frame

stripes where the black merges gradually into

into which different lenses can be slotted. In the

the white. Such a grating can be varied by alter-

case of young children, it is usually advisable to

ing either the contrast of black and white or the

instill a mydriatic and cycloplegic drop before-

width of the stripes (the “frequency”). Thus, for

hand to eliminate focusing. The ophthalmol-

a given individual, the threshold for contrast

ogist then views the eye to be examined through

and frequency

(contrast sensitivity) can be

an instrument known as a retinoscope, from

measured. This type of test has certain theor-

a distance of about one arm’s length. The red

etical advantages over standard methods but it

reflex can be seen and the instrument is then

is not widely used clinically as a routine. Finally,

moved slightly so that the light projected from

the electrical potentials generated by the retina

the retinoscope moves to and fro across the

and optic nerve can be measured to give an esti-

pupil. The shadow of the iris on the red reflex is

mate of visual acuity when the eye is presented

then seen to move, and the direction and speed

with targets of varying size and contrast. This

of movement depend on the refractive error of

method is useful in infants and in the assess-

the patient. By interposing different lenses in the

ment of adults with nonorganic visual loss.

trial frame,the movement of the iris shadow can

be “neutralised” and the exact refractive error

determined. The trial frame can accommodate

both spherical and cylindrical lenses so that the

Measuring for Spectacles

amount of astigmatism can be measured.

If a patient has not been tested recently for spec-

Subjective Refraction

tacles, not only can the measurement of visual

acuity be inaccurate, but the symptoms might

Here, considerable skill is also needed because

be caused by the need for a correct pair of

many patients become quite tense when being

glasses. The measurement, which determines

tested in this way and might not initially give

the type of spectacles needed, requires skill

accurate answers. Lenses both stronger and

developed by practice and the use of the right

weaker than the expected requirement are

equipment. The most obvious way to measure

placed in the trial frames and the patient is

someone for a pair of glasses is to try the effect

asked to read the letters of the Snellen chart and

of different lenses and ask the patient whether

to say whether they are more or less clear. A

the letters are seen better with one lens or

number of supplementary tests are available,

another. This is known as subjective testing and,

which enable one to check the patients’ answers.

by itself, it is not a accurate method because

It can be seen that the word “refraction” refers

some patients’ observations as to the clarity of

to the total test for glasses, although the same

letters can be unreliable. Furthermore, a healthy

word refers to the bending of the rays of light

young person might see quite clearly with a

as they pass from one medium to another.

wide range of lenses simply by exercising the

Accurate refraction takes 10 min or 15 min to

ciliary muscle

(i.e., accommodation). Fortu-

perform, or longer in difficult cases and it is an

nately, the refractive error of the eye can be

essential preliminary to an examination of the

measured by an objective method and an

eye itself.

answer can be reached without consulting the

patient. The method entails observing the rate

Automated Refraction

of movement of the shadow of the iris against

the red reflex from the fundus of the eye after

In recent years attempts have been made to

interposing different strengths of lenses

develop an automated system of refraction, and

(retinoscopy). In order to make an accurate

instruments are now commercially available.

measurement of the spectacle requirement,

They are, however, still expensive and not always

140

Common Eye Diseases and their Management

accurate when there are opacities in the optical

number of tests have been developed for this,

media, or when the patient overaccommodates.

but the simple Snellen chart remains an essen-

One further way of assessing the refractive error

tial part of any doctor’s surgery. It must be

without asking the patient any questions is by

remembered that this is a measure of function

making use of the visually evoked response.

in the centre of the visual field only and it is pos-

This is the name given to the minute electrical

sible to have advanced loss of peripheral vision

changes detectable over the back of the scalp

with normal visual acuity, as is seen sometimes

when the eyes are exposed to a repeated stim-

in patients with chronic glaucoma or retinitis

ulus, usually a flashing checkerboard. When fine

pigmentosa. The assessment of the rest of the

checks are viewed, interposing different lenses

visual field has also been standardised and a

can modify the response. This method is of

number of instruments have been developed to

great interest but it is still not reliable and takes

measure it. These have already been described

time to perform.

in Chapter 3 together with various other meas-

Considering the importance of the measure-

urements of different aspects of vision.

ment of visual acuity, it is not surprising that a

The Inflamed Eye

In an earlier chapter, we have already seen that

amiss with the eye. The vision is blurred and the

“the red eye” is an important sign in ophthal-

eye aches and can often be extremely painful.

mology, and there are a number of reasons why

Photophobia is usual and often pain on focusing

the eye can become inflamed. When the exposed

on near objects is a feature. The age incidence is

parts of the eye, such as the conjunctiva and the

wide but anterior uveitis is commonly seen in

cornea, are the primary sites of inflammation,

the third and fourth decades of life, and every

the cause is usually infection or trauma.

eye casualty officer becomes familiar with this

Common examples are chronic conjunctivitis or

particular form. When the disease presents for

a corneal foreign body. However, here we are

the first time in the elderly, the underlying cause

going to consider a type of inflammation that

is likely to be different and age provides an

arises deeper in the eye and primarily from the

important diagnostic feature. Acute anterior

uvea. The uvea has a tendency to become

uveitis usually appears quite suddenly over a

inflamed for no apparent external reason and in

period of about 24 h and then resolves on treat-

this respect can be compared to a joint; indeed,

ment in two or three weeks; however, it may last

there is a recognised association between uveitis

as long as six weeks. A further exacerbation

and arthritis. In spite of the fact that the eye is

might occur during this period and there is

open to microscopic examination, the exact

a strong tendency towards recurrence after a

cause of uveitis is usually obscure,although there

few months or several years in the same or the

is evidence to indicate a relationship with other

other eye.

kinds of autoimmune disease. Uveitis can be

divided into anterior or posterior uveitis; ante-

Signs

rior uveitis is the same entity as iridocyclitis, and

posterior uveitis is the same as choroiditis.Apart

The eye is red, but of especial importance is the

from the uvea, the sclera and the episclera (that

presence of a pink flush around the cornea (the

is, the connective tissue deep to the conjunctiva

ciliary flush), which indicates an inflammatory

and overlying the sclera) can also be affected by

process either in the cornea or within the anter-

similar inflammatory changes.

ior chamber of the eye itself. The pupil is small

because the iris sphincter goes into spasm.

Thus, the pupil of iritis is small and treatment

Anterior Uveitis

is aimed at making it larger, whereas the pupil

of acute glaucoma is large and treatment is

Symptoms

aimed at making it smaller. Unless there is sec-

The patient suffering from acute anterior uveitis

ondary glaucoma, the cornea remains bright

is usually aware that there is something seriously

and clear, but with a pen torch it might be pos-

141

142

Common Eye Diseases and their Management

sible to see that the aqueous looks turbid. That

is to say, a beam of light shone through the

aqueous resembles a beam of sunlight shining

through a dusty room (Figure 18.1). Normally,

of course, the aqueous is crystal clear even when

examined with the slit-lamp biomicroscope.

The presence of an occasional cell in the

aqueous can be normal, especially if the pupil

has been dilated with mydriatic eye drops, but

suspicion should be raised if more than three or

four cells are seen. In fact, the early diagnosis of

anterior uveitis can entail careful slit-lamp

examination. It is usual to discriminate between

the presence of cells in the aqueous and the

Figure 18.2. Keratic precipitates.

presence of flare. The latter reflects a high

protein content and is a feature of more long-

standing disease. Because there are convection

but they can remain more permanently as pig-

currents in the aqueous, inflammatory cells are

mented spots on the endothelium.

swept down the centre of the posterior surface

Anterior uveitis is often associated with the

of the cornea and become adherent to it, often

formation of adhesions between the posterior

forming a triangular-shaped spread of deposits

surface of the iris and the lens. These are called

known as keratic precipitates, or “KP”s (Figure

posterior synechiae and become evident when

18.2). The microscopic appearance of the KP is

attempts are made to dilate the pupil because

determined by the type of cells. If a granulo-

parts of the iris remain stuck to the pupil giving

matous type of inflammatory reaction is taking

it an irregular appearance. In severe cases of

place, involving epithelioid cells and macro-

anterior uveitis, pus can collect in the anterior

phages, the KP might be large, resembling oil

chamber to the extent that a fluid level can be

droplets (“mutton fat KP”). This form of KP is

seen where the layer of pus has formed inferi-

seen in uveitis associated with sarcoidosis and

orly. This is known as hypopyon - literally, “pus

also tuberculosis and leprosy. When the

below” (Figure 18.3). A hypopyon is an indica-

inflammation is nongranulomatous, a fine

tion of severe disease in the eye and the patient

dusting of the posterior surface of the cornea

could be evident. KPs tend to become absorbed

Figure 18.3. Hypopyon. In addition, there are red blood cells

and fibrinous exudate in the anterior chamber (with acknowl-

Figure 18.1. Flare.

edgement to Professor H. Dua).

The Inflamed Eye

143

should preferably be treated in hospital as an

negative result will be obtained. It is necessary

inpatient. Hypopyon tends to occur in certain

to explain this to patients otherwise consider-

specific types of anterior uveitis. It is occasion-

able anxiety might be created by the fact that

ally seen in elderly diabetics with inadequately

“no cause can be found” for their complaint.

treated corneal ulcers, particularly those with

When we say no cause can be found, we really

vascular occlusive disease. It is also seen in

mean that there is no evidence of any associated

Behçet’s disease, which is a rare disorder char-

systemic disease and this should be of some

acterised by hypopyon uveitis, and ulceration of

reassurance to the patient.

the mouth and genitalia. A hypopyon is occa-

It has already been mentioned that it can be

sionally seen following cataract surgery and in

helpful to consider the age of the patient when

such cases can be infective or noninfective in

trying to eliminate the possibility of underlying

origin. It is fortunately a rare complication of

systemic disease. Uveitis is rare in young chil-

modern cataract surgery and the use of intra-

dren, but when seen, the possibility of juvenile

ocular acrylic lenses.

rheumatoid arthritis must be borne in mind.

In young adults, sarcoidosis, gonorrhoea,

Reiter’s disease and ankylosing spondylitis are

Complications

all recognised associations. In former years,

The visual prognosis of acute anterior uveitis

tuberculosis was high on the list of suspected

as commonly seen in young people is usually

causes but this would appear to be a less

good unless recurrences are frequent. Chronic

common cause nowadays. Herpes simplex and

uveitis is more prone to complications. Sec-

zoster can also cause anterior uveitis. Septic foci

ondary glaucoma can cause serious problems

in adjacent structures, such as dental sepsis or

and a careful check on the intraocular pressure

sinusitis, have also been under suspicion but

must be maintained. The rise in intraocular

these are now thought to be relatively unimpor-

pressure might be due to direct obstruction of

tant. In the case of the elderly, the onset of

the aqueous outflow by inflammatory cells or by

anterior uveitis can prove to be a recurrence

the presence of adhesions between the periph-

of previous attacks and the same underlying

eral part of the iris and the posterior surface of

causes must be suspected, but here there is also

the cornea

(peripheral anterior synechiae).

the possibility of lens-induced uveitis asso-

Sometimes, especially when treatment has been

ciated with hypermature cataract. Three other

inadequate, the posterior synechiae sticking

types specific of anterior uveitis must be men-

the pupil margin to the anterior surface of the

tioned at this stage.

lens become extensive enough to obstruct the

passage of aqueous through the pupil. The iris

Sympathetic Ophthalmia

bulges forward, giving the appearance known as

iris bombe. Secondary glaucoma can also result

This is a rare but dramatic response of the uvea

from the use of topical steroids in predisposed

in both eyes to trauma. The significance of the

individuals. Cataract is a further serious com-

condition rests in the fact that although the

plication, which can appear after repeated

trauma has only affected one eye, the inflam-

attacks of anterior uveitis. It nearly always first

matory reaction occurs in both. It can follow

affects the posterior subcapsular zone of the lens

perforating injuries, especially when uveal

and, unfortunately, interferes with the vision at

tissue has become adherent to the wound edges.

an early stage. Cataracts can also result from

Occasionally it can occur following intraocular

long-term use of topical or systemic steroids.

surgery. The injured eye, which is referred to

as the “exciting eye”, remains severely inflamed

and, after an interval of between two weeks and

Causes

several years, the uninjured eye (“sympathising

For the majority of patients who present to eye

eye”) becomes affected. The inflammation in the

outpatient departments with this condition, no

sympathising eye usually starts in the region

specific cause is found. However, there are many

of the ciliary body and spreads anteriorly and

known causative agents. The ophthalmologist is

posteriorly. It is granulomatous. Careful wound

obliged to exclude at least some of these, even

toilet and repair of the injured eye can prob-

though he knows that more often than not a

ably prevent many cases, as can also removal of

144

Common Eye Diseases and their Management

blind, painful and inflamed eyes within the crit-

some infective types of anterior uveitis, the

ical two-week period following injury.

diagnosis is usually made before the uveitis

appears because the condition occurs as a sec-

ondary event. This is the case following herpes

Heterochromic Iridocyclitis

simplex keratitis and also in patients with

herpes zoster affecting the upper division of the

This type of anterior uveitis presents in 20-40

fifth cranial nerve. By contrast, anterior uveitis

year olds and is usually unilateral. The vision

can be an important clue to the diagnosis of a

becomes blurred and the iris becomes depig-

venereal disease.

mented. The eye usually remains white, the

The treatment involves the administration of

inflammatory reaction is low grade and chronic;

local steroids and mydriatic drops. When the

posterior synechiae do not develop. The

condition is severe, a subconjunctival injection

inflammation does not usually respond at all to

of steroid should be given and relief of symp-

treatment. Cataracts and chronic glaucoma

toms can be further achieved by local heat in the

occur commonly. The condition has been mim-

form of a warm compress.Atropine is the mydri-

icked by denervating the sympathetic supply of

atic of first choice except in the mildest cases,

the eyes in experimental animals and it seems

when homatropine or cyclopentolate drops can

possible that there might be a neurological

be used. Steroid drops should be administered

cause, unrelated and distinct from other types

every hour during the acute stage and then

of uveitis.

gradually tailed off over a period of a few weeks.

Systemic steroids are not usually indicated and

Pars Planitis (Intermediate Uveitis)

should be reserved for those cases in which the

sight becomes seriously jeopardised. If any

This refers to a low-grade inflammatory

underlying systemic disease is identified, then,

response, which is seen in young adults. It affects

of course, this should also be treated if effective

both eyes in up to 80% of cases, although the

treatment is available. The proper management

severity can be asymmetrical. There is minimal

of anterior uveitis demands the expertise of a

evidence of anterior uveitis and the patient

specialist ophthalmologist and, when the condi-

complains of floating spots in front of the

tion is affecting both eyes, it might be preferable

vision. Inspection of the fundus reveals vitreous

to admit the patient to hospital.

opacities and careful inspection of the periph-

A special word of warning is needed for those

eral retina shows whitish exudates in the over-

patients who have undergone previous intra-

lying vitreous. A mild-to-moderate peripheral

ocular surgery. For these patients, what is nor-

retinal phlebitis can occur. The condition runs

mally a mild infective conjunctivitis can lead to

a chronic course and occasionally can be com-

intraocular infection. The development of anter-

plicated by cataract, cystoid macular oedema

ior uveitis, weeks, and occasionally even years,

and tractional retinal detachment. The cause is

after the operation, can indicate disastrous

unknown in the majority of cases, although

consequences if urgent and intensive antibiotic

there is a known association with sarcoidosis.

treatment is not applied.

Treatment and Management

Posterior Uveitis

Once the diagnosis has been made, it is usual to

embark on a number of investigations, guided

Symptoms

in part by the history and especially taking into

account any previous chest or joint disease. An

When the choroid, as opposed to the ciliary body

X-ray of the chest, and a blood count, including

and iris, becomes inflamed, the eye is not usually

measurement of the erythrocyte sedimentation

painful or red and the patient complains of

rate (ESR), are routine in most clinics, but the

severe blurring or loss of vision. If the focus of

expense of further investigations is now often

choroiditis remains peripheral, the disease

spared if the patient appears completely fit and

might remain unnoticed, as is witnessed by the

well in other respects. The history and back-

relatively frequent observation of isolated

ground of the patient might lead one to suspect

healed foci in the fundi of asymptomatic

the possibility of venereal disease. In the case of

patients. Often, the inflammation spreads from

The Inflamed Eye

145

choroid to retina and then to the vitreous. When

this happens the vision becomes markedly

blurred, even when the original focus is remote

from the macula region. Alternatively, the

inflammation might originate from the retina

and spread to involve the choroid and vitreous

subsequently. Choroiditis at the macula itself

usually leads to permanent loss of central vision.

Signs

In its early stages, choroiditis can be seen as a

grey or yellowish raised area, which can be dis-

crete or multiple and anywhere in the fundus. A

cellular reaction could appear in the overlying

vitreous, seen as localised misting with the

ophthalmoscope, and eventually the whole vit-

reous can become clouded, obscuring any view

of the fundus and the original site of inflamma-

tion. The patient usually presents at this stage so

that the origin of the problem only becomes

apparent after the inflammation has subsided.

Retinitis manifests as an indistinct white cloudy

area. When a patch of choroiditis heals, the

margins become pigmented and a white patch

of bare sclera remains (Figure 18.4). This is the

result of atrophy of the pigment epithelium and

choroid. Sometimes larger choroidal vessels

survive as a clearly seen network overlying the

white sclera surrounded by a pigment halo.

During the active stage, inspection of the vit-

reous with the slit-lamp reveals the presence of

cells and often the anterior chamber also con-

tains cells. Posterior uveitis comes into the dif-

ferential diagnosis of a white eye with failing

Figure

18.4.

Chorioretinitis:

active

with

hazy

vitreous;

vision. When the vitreous becomes cloudy, the

b inactive scar.

condition must be distinguished from vitreous

haemorrhage. The latter nearly always occurs

acutely over a period of hours, whereas the

However, a number of

systemic associations

cloudiness following uveitis takes a few days to

have been recognised and often are related to

develop. Examination of the vitreous with the

specific types of posterior uveitis.

slit-lamp can reveal whether the vitreous is

filled with inflammatory cells or red cells.

Toxoplasmosis

Retinal vasculitis can occur. A predominantly

arteriolar inflammation can indicate a viral

Toxoplasma gondii is a parasite, a protozoan

cause, whereas venous involvement is more

carried by cats. Man and other intermediate

common with other aetiologies. Optic nerve

hosts can be infected. In the adult with the

inflammation or oedema can also occur.

acquired infection, systemic symptoms are

usually mild. Similarly, the ocular symptoms of

acquired toxoplasmosis can be mild. However, a

Causes

severe form of acquired ocular toxoplasmosis

As in the case of anterior uveitis, it is often

has been recognised. In such cases, there has

impossible to pinpoint any systemic cause and

been contact with wild cats in stables.In the case

the condition seems to be confined to the eye.

of infected pregnant mothers, the child in utero

146

Common Eye Diseases and their Management

could be infected by the more severe congenital

scarring at the macular region. Recurrences are

form of the disease. The organism enters the

fairly common, with or without treatment, and

brain as well as the eyes and can cause mental

the fresh choroidal inflammation tends to arise

deficiency and epilepsy. A characteristic type of

at the edge of a previous scar.

calcification is seen on skull X-ray or computed

tomography (CT) scan. In the eye, a focal type

Toxocariasis

of choroiditis often affects both eyes and this is

usually at the posterior pole in the macular

Toxocariasis is caused by Toxocara cati (from

region. Histologically, the toxoplasma organism

cats) or T. canis (from dogs). This nematode has

is found in the eye lesions. The diagnosis can be

been found in the enucleated eyes of young

confirmed by sending some blood for serologi-

patients with a severe type of chorioretinitis.

cal tests. Four such tests are currently in use

It is a unilateral disease found in children who

clinically: the toxoplasma dye test, indirect

are in close contact with puppies or eat dirt

fluorescent antibody test, haemaglutination test

(through faecal contamination). The vitreous

and enzyme-linked immunosorbent assay

tends to be filled with a white mass of inflam-

(ELISA). These tests must be interpreted care-

matory cells so that the presence of a tumour

fully because a high proportion of the popula-

might be suspected (e.g., retinoblastoma). End-

tion becomes infected at some point and the

ophthalmitis tends to develop in these cases and

positive results increase with age, even in those

the sight of one eye might be completely lost.

with no clinical evidence of infection. For this

During the acute stage, the peripheral blood

reason, the diagnosis can be less easy in

can show an eosinophilia. Treatment is un-

acquired toxoplasmosis, where evidence of sys-

satisfactory and includes a combination of

temic involvement can be slight or absent. It has

antihelminthic agent taken by mouth (thioben-

been shown that there is a higher incidence of

dazole or diethylcarbamazine) and steroids.

positive dye tests in patients with posterior

uveitis than in the normal population, but in an

individual case it is often necessary to demon-

Tuberculosis

strate a changing titre in order to confirm the

diagnosis. The most specific of these tests is

In former years this was considered to be a

the ELISA.

common cause of posterior uveitis, clinicians

All the currently available antitoxoplasma

having been impressed by the number of patients

treatments have potentially serious side effects.

with a previous history of tuberculosis. The rela-

Therefore, not all active toxoplasma retino-

tionship seems less likely now that tuberculosis

choroiditis lesions require treatment. Such

has been almost eliminated from the population.

treatment is required only if an active lesion

However, this diagnosis must not be forgotten

involves or threatens the fovea and/or optic

especially in the immunosuppressed patient

nerve. Treatment is also required when there is

and those with recalcitrant or atypical uveitis,

severe vitritis.

as there is currently a slight re-emergence of

A combination of pyrimethamine and sulfa-

the disease. Choroidal tubercles are a well-

diazine has been recommended, but such treat-

described entity: these raised yellowish granulo-

ment can cause a serious fall in the white cell

matous foci were used as a diagnostic feature of

count. An alternative antimicrobial treatment is

miliary tuberculosis and, occasionally, chronic

clindamycin. This needs to be given with a sul-

pulmonary tuberculosis. They are usually seen in

fonamide in order to reduce the risk of colitis.

extremely ill patients and the yellowish tubercles

Other antitoxoplasma agents include atova-

become pigmented as they heal. Treatment is as

quone. It is generally accepted that systemic

for systemic tuberculosis.

steroids have some beneficial effect and can

help to clear the vitreous more rapidly, but this

Sarcoidosis

treatment should be given only with antimicro-

bial cover. Steroids on their own will produce

The eye is frequently involved in sarcoidosis.

exacerbation or progression of the chorioretin-

Involvement usually takes the form of an

itis. In fact, the majority of cases resolve spon-

anterior or posterior uveitis. The choroiditis

taneously, leaving more or less chorioretinal

is more often peripheral and accompanied by

The Inflamed Eye

147

inflammatory changes in the retinal veins.

carry out serological testing. The T. pallidum

Sheathing of the veins can be seen and the

immobilisation test and the fluorescent tre-

vision might be impaired by macular oedema.

ponemal antibody test are the most sensitive

The inflammatory changes might be similar to

and specific.

those seen in pars planitis. When the diagnosis

is suspected, the conjunctiva and skin should be

searched for possible nodules, which can be

Behçet’s Disease

biopsied, and an X-ray of the chest can reveal

Behçet’s disease is a multisystem disease asso-

enlargement of the hilar lymph nodes. The

ciated with HLA-B5. It was originally thought

management of the ophthalmological problem

to occur only in the Mediterranean and Japan,

might involve treatment with local and systemic

where it is most common. It is characterised by

steroids but the opinion of a physician special-

an obliterative vasculitis. The clinical syndrome

ising in sarcoidosis is essential and should be

consists of oral and genital ulceration in com-

sought before embarking on treatment.

bination with recurrent uveitis and skin lesions.

The uveitis consists of recurrent bilateral non-

Presumed Ocular Histoplasmosis

granulomatous anterior and/or posterior

uveitis. Central nervous system involvement

Histoplasmosis is a fungal infection (causative

occurs as a serious form of the disease.

agent Histoplasma capsulatum). Infection with

this organism occurs throughout the world but

is more common in the Mississippi Valley and

Other Causes

does not occur in the UK. A severe pneumonitis

can occur but most cases are asymptomatic.

A wide variety of infective agents have been

Presumed ocular histoplasmosis is not seen

shown to cause posterior uveitis on rare occa-

in patients with active histoplasmosis. The evi-

sions. The leprosy bacillus and the coxsackie

dence for infection in the originally described

group of viruses are two examples chosen from

cases was necessarily circumstantial - hence the

many. Sympathetic ophthalmia has already been

expression “presumed ocular histoplasmosis”.

mentioned as a specific form of uveitis following

The syndrome consists of a certain type of

injury. An especially rare but intriguing form of

haemorrhagic macular lesion (choroidal neo-

uveitis is known as the Vogt-Koyanagi-Harada

vascularisation) combined with discrete foci of

syndrome, in which is seen the combination of

peripheral choroiditis and peripapillary scars.

vitiligo, poliosis, meningo-encephalitis, uveitis

and exudative retinal detachments.

Syphilis

Syphilis is a chronic infection caused by Tre-

The Role of Autoimmunity

ponema pallidum. Iridocyclitis occurs in

patients with secondary acquired syphilis. It is

in Uveitis

a bilateral disease in which the iris vessels are

particularly engorged. Chorioretinitis can be

Although it has been recognised for a long time

either multifocal or diffuse and involves the

that bacterial and viral infection can account

mid periphery and peripapillary area. In the

for some cases of uveitis, it has also been

healed phase, perivascular bone spicule pig-

recognised that the majority of cases fail to

mentation could be seen similar to that

show any evidence of this. Furthermore, in

observed in retinitis pigmentosa.

many instances the eye disease may be associ-

In congenital syphilis, other possible features

ated with known autoimmune disease elsewhere

occur such as deafness and corneal scarring

in the body. There are several different ways in

from previous interstitial keratitis. The scat-

which the uvea might be expected to become the

tered pigmentation in the fundus might suggest

focus of an antigen-antibody reaction. A

an inherited retinal degeneration but a careful

foreign agent such as a virus might reside in the

family history together with electrodiagnostic

uvea and cause an antibody response, which

testing of the eyes usually enables one to distin-

coincidentally involves uveal tissue, or, on the

guish the two conditions. It is also important to

other hand, a foreign agent might react with a

148

Common Eye Diseases and their Management

specific marker on the cell membrane to

selected patients with toxoplasma retinocho-

produce a new active antigen. It is now recog-

roiditis. The rationale of this treatment is to

nised that patients who inherit certain of the

destroy any remaining encysted organisms.

human leucocyte antigens (HLA) are more sus-

ceptible to particular types of uveitis, for

example the uveitis seen in ankylosing

Endophthalmitis and

spondylitis and Reiter’s disease (HLA-B27). It

has been suggested that HLA might act as the

Panophthalmitis

specific marker in these cases. A further way in

which the uvea might become the centre of an

When inflammatory changes in the posterior

immune response concerns the question of

uvea extend into the vitreous and there is an

self-recognition. It now appears that there is

extensive involvement of the centre of the globe,

a mechanism in the body that normally pre-

the patient is said to have endophthalmitis.

vents antibodies in the serum from acting

Further extension of the inflammation into the

against our own tissues. This active suppression

anterior segment of the eye and into the sclera

is maintained by a population of thymus-

leads to panophthalmitis. Endophthalmitis is

derived lymphocytes (T lymphocytes) known

one of the feared results of infection after injury

as T-suppressor cells. There is evidence to

or surgery but it can prove reversible with inten-

suggest that sympathetic ophthalmitis might

sive antibiotic treatment. When endophthal-

arise from inhibition of the T-suppressor cells

mitis and panophthalmitis are not properly

after uveal antigens have been introduced into

and aggressively treated, the sight is usually

the bloodstream. Patients with juvenile rheum-

lost permanently and after months or years the

atoid arthritis occasionally develop uveitis,

whole eye begins to shrink.

whereas rheumatoid disease in adults is more

commonly associated with the dry eye syn-

drome and episcleritis.

Episcleritis and Scleritis

Both these conditions form part of the differen-

Management

tial diagnosis of the red eye. The episclera is the

Increased interest in immunological diseases in

connective tissue underlying the conjunctiva

recent years, which has accompanied advances

and it can become selectively inflamed, either

in tissue grafting and cancer research, has led

diffusely or in localised nodules. In the case of

to attempts to treat uveitis with means other

episcleritis, close inspection of the eyes shows

than steroids. Immunosuppressive agents, such

that the inflammation is deeper than the con-

as cyclosporin A, tacrolimus, azathioprine, and

junctiva and there is a notable absence of any

cyclophosphamide, are now sometimes used to

discharge. The eye is red and can be gritty but

supplement or replace steroids in difficult cases.

not painful. Episcleritis is seen from time to

If posterior uveitis is not due to any recognisable

time in the casualty department and the

infective cause, it is usual to start treatment with

patient might be otherwise perfectly fit and

systemic steroids if the visual acuity becomes

well. Such cases tend to recur and some develop

significantly impaired or if the lesion is close

signs of dermatological disease. The condi-

to the macula. Large doses of systemic steroids

tion responds to local steroids, but systemic

are best administered on an inpatient basis,

aspirin can also prove effective. Scleritis is

especially if the sight is threatened. This has the

less common and more closely linked with

added advantage of allowing a more detailed

rheumatoid arthritis and other collagen dis-

pretreatment examination and investigations,

eases. The eye is red (diffuse or localised) and

and often the opinion of a general physician or

painful. In severe cases, the sclera can be-

immunologist can be valuable at this stage.

come eroded with prolapse of uveal tissue.

Secondary glaucoma might also need to be

Topical treatment is of no benefit. The condition

treated and immunosuppressive agents can be

responds to systemic anti-inflammatory agents,

administered to resistant cases. When posterior

particularly oral flurbiprofen (Froben), which

uveitis keeps recurring at the edge of previous

can be supplemented with systemic steroids

healed foci, laser coagulation has been used in

and/or immunosuppressants.

The Ageing Eye

Although the eye and its supporting structures

ment owing to glaucoma is more prevalent and

undergo a number of well-defined changes with

occurs at an earlier age in blacks than in whites.

age, the distinction between these involutional

Although there is an unexpectedly high inci-

changes and disease is not always clear cut. For

dence of cataract in patients with chronic

the elderly patient, it is often reassuring to know

simple glaucoma, the association of macular

that the problem is part of a “normal” process

degeneration with cataract or glaucoma is

rather than the result of a specific illness and

more random.

perhaps sometimes an artificial demarcation is

drawn for the benefit of the patient.

The increase in number of elderly people

presents problems in ophthalmology. A high

Changes in the Eyes with Age

proportion of elderly people instill drops into

their eyes, either prescribed for them or as

The External Eye

self-medication. It is important that adequate

advice is received. Advising the elderly is often

The eyelids tend to lose their elasticity and

time consuming and might entail speaking to a

become less firmly opposed to the globe. The

younger relative or neighbour, but an adequate

upper and lower lid margins become progres-

explanation of the disease or problems will

sively lower so that whereas in the infant the

avoid anxiety and probably the need for further

upper lid can ride level with or slightly above the

subsequent unnecessary consultation.

corneal margin, in an elderly subject the upper

The three commonest diseases of the elderly

lid might cross a significant part of the upper

eye are cataract, glaucoma and age-related

cornea. An area of white can be seen between

macular degeneration (AMD). The first can be

the lower margin of the cornea and the lower

cured, the second arrested or prevented, while

lid. Some limitation of the ocular movements

the third generally tends to run a progressive

is accepted as normal in the elderly, especially

course and treatment is unsatisfactory at

limitation of upward gaze. The conjunctiva

present, although significant progress has been

tends to become more lax and a thin fold of con-

made recently. Attempts to measure the inci-

junctiva might be trapped between the lids

dence of these problems have produced a wide

when blinking if this becomes excessive. In

range of figures. Out of a population of elderly

some elderly patients, there is loss of connective

persons complaining of impaired vision, about

tissue around the lacrimal puncta so that the

30% turn out to have a cataract and a similar

opening is seen elevated slightly from the rest

number to have AMD, whereas 5% or less have

of the lid. Degenerative plaques are seen on

chronic open-angle glaucoma. Visual impair-

the bulbar conjunctiva in the exposed region

149

150

Common Eye Diseases and their Management

and the conjunctiva is especially prone to

light reflex is less marked. The optic disc tends

chronic inflammation.

to become somewhat paler and a degree of optic

atrophy is accepted by many clinicians as a senile

change unrelated to disease.

The Globe

Arcus senilis is the name given to the circular

white infiltrate seen around the margin of the

Eye Disease in the Elderly

cornea. The lens gradually loses its plasticity

throughout life and this results in a progressive

The prevalence of blindness increases with age.

reduction in the focusing power of the eye. This

The prevalence and causes of blindness also

loss of focusing ability is also contributed to by

vary from one community to another depend-

the progressive loss of ciliary muscle tone. A

ing on the age structure of the population and

child might be able to observe details of an

environmental conditions. In England and

object held 5 cm from the eye, but as a result of

Wales (1980), the prevalence of blindness was

hardening of the lens and weakening of the

found to be nine per 100,000 children under five

ciliary muscle, the nearest point at which an

years of age and 2324 per 100,000 individuals

object can be kept in focus gradually recedes.

above 75 years.

This progressive degeneration tends to pass

A recent survey in the USA has shown that the

unnoticed until the eye is no longer able to focus

incidence of cataract in the

45-64-year-old

to within the normal reading distance. This

population is

5.6% for males and 2.1% for

usually occurs at the age of 45 years if the eyes

females. The incidence is slightly higher in the

are otherwise normal, and the phenomenon is

Negro population, and rises to 21.6% for males

called presbyopia. Some degree of opacity of

and 26.8% for females in the 65-75-year-old

the lens fibres is common in old age and only

population. In the same age group (65-75 years),

when this becomes more extensive is the term

the incidence of AMD is 9.6% for males and

“cataract” used. The pupil becomes smaller with

6.9% for females. Both these conditions are,

age and does not show the wide range of adjust-

therefore, common and they demand time and

ment to illumination seen in younger people.

medical expertise, both at the primary care level

The vitreous shows an increase in small opaci-

and in hospital.

ties visible to the subject as “vitreous floaters”.

With increasing longevity throughout the

A more dramatic degenerative change, which

world, especially in the developing countries,

occurs in a high proportion of normal individ-

there will be a continuing increase in the

uals in the 60-70-year age group, is detachment

number of blind people, especially those suffer-

of the vitreous. The formed part of the vitreous

ing from diseases related to age, such as

separates from the retina, usually above at first,

cataracts, glaucoma and macular degeneration.

leaving a fluid-filled gap between the retina and

posterior vitreous face. Movement of the vitre-

Age-related Macular Degeneration

ous face can cause troublesome symptoms, for

example flashing lights and floaters, but often a

AMD is the commonest cause of incurable

vitreous detachment goes unnoticed and is an

blindness in the elderly in western countries. It

incidental finding on examination of the eye.

is a bilateral disease in which visual loss in the

The important association between sudden

first eye usually occurs at about 65 years of age.

vitreous detachment and subsequent retinal

The second eye is involved at the rate of approx-

detachment has already been discussed in

imately 10% per annum and accounts for half of

Chapter 13. The appearance of the fundus also

all registered visual impairments in the UK.

shows gradual changes; the retinal arterioles

There are two main types of AMD: “dry” or

become straighter and narrower, as also do the

atrophic, and “wet” or neovascular. Blindness is

venules. Colloid bodies or drusen are more com-

usually associated with the wet form of AMD,

monly seen because of degenerative changes in

and among the eyes with severe visual loss,

Bruch’s membrane and the pigment epithelium,

80-90% of cases are because of wet AMD, while

and peripheral chorioretinal degeneration is

10-20% are because of the dry form.

more evident. The young retina is more shiny

Older patients with macular degeneration

than the old retina and in the elderly the normal

complain of blurring of their vision and inability

The Ageing Eye

151

to read. Younger or more observant patients

notice that straight edges might look kinked.

Usually one eye is considerably more affected

than the other, although both eyes can be

affected simultaneously. Because the degener-

ative process is limited to the macula, the periph-

eral field remains unaffected and the patient can

walk around quite normally. Difficulty in recog-

nising faces or in seeing bus numbers is also a

common complaint. The wet form occurs more

commonly in Caucasians and about one-third of

the patients give a family history of similar prob-

lems. Several preventable factors, including

smoking, systemic hypertension, cardiovascular

disease and low antioxidant intake, are asso-

Figure 19.2. Dry macular degeneration.

ciated with increased risk of AMD.

In the early stages of dry AMD, inspection of

the fundus shows spots of pigment in the

macular region. Drusen are also often seen

Under the microscope, colloid bodies are seen

(Figure 19.1). These are small round yellowish

as a degenerative change in Bruch’s membrane.

spots, often scattered over the posterior pole.

Drusen can have varying degrees of hyperpig-

Unfortunately, the word “drusen” has been used

mentation. Most eyes with drusen maintain

rather loosely in ophthalmology to refer to two

good vision, but a significant number will

or three types of swelling seen in the fundus. It

develop progressive atrophy of the retinal

is used to describe the rare mulberry-like

pigment epithelium (RPE) and choriocapillaris.

tumours seen around the optic nerve head in

This is inevitably associated with photoreceptor

tuberose sclerosis and it is also used when refer-

loss (Figure 19.2). There is usually a moderate

ring to the multiple shiny excrescences seen on

loss of vision. This atrophic change in the

the optic disc as a congenital abnormality.

RPE, choroid and photoreceptors is referred

Drusen seen at the posterior pole of the eye as

to as “dry” AMD. This is because there is no

a senile change are also known as “colloid

leakage of fluid or bleeding into the retina or

bodies” and perhaps this term is preferable.

subretinal space.

In the “wet type” of macular degeneration a

fan of new vessels arises from the choroid -

choroidal neovascularisation (CNV).The growth

of these new vessels seems to be important

because they invade the breaks in Bruch’s

membrane. Serous or haemorrhagic exudate

tends to occur and this can be either under the

RPE or subretinal (Figure 19.3). A sudden loss of

central vision might be experienced as the result

of such an episode. Subsequently,“healing”of the

leaking vascular complex results in scar tissue

formation, which further destroys the central

vision permanently.

The terms “classic” and “occult” describe

the different patterns of CNV leakage on

fluorescein angiography.

Management

No effective treatment is available for dry AMD.

Figure 19.1. Drusen.

There is an increasing vogue for administering

152

Common Eye Diseases and their Management

Figure 19.3. Wet macular degeneration: a Fundus photograph:

early disease. b Fundus photograph: advanced disease.

c Fluorescein angiogram: early disease.

vitamins A, C and E, selenium, copper, zinc,

patients present at the stage when new vessels

zeaxanthin, carotenoids and lutein preparations

have already advanced across the macular

to patients. These have been shown to protect

region to the subfoveal area or where the fovea

against progression of dry AMD to more

has already been permanently damaged by

advanced stages of the disease in high-risk

haemorrhage or exudate, making effective laser

patients. They are thought to reduce the dam-

treatment impossible. Only about 10-20% of

aging effects of light on the retina through their

cases of CNV are eligible for laser photocoag-

reducing and free-radical scavenging actions.

ulation. Another limitation of laser treatment is

Some types/stages of wet AMD are treatable.

the high rate of recurrence of the CNV within a

Currently, there are two clinically proven treat-

short time following treatment.

ments for wet AMD, although the treatment for

The second proven treatment is photo-

some eyes is still unsatisfactory.

dynamic therapy (PDT) with verteporfin (Visu-

Controlled trials of the effect of laser photo-

dyne). PDT specifically targets the CNV

coagulation of the choroidal new vessels have

complex for damage by low-energy laser, but

shown that this treatment is useful in

avoids damage to the unaffected tissue, includ-

extrafoveal CNV (i.e., when the leakage is not

ing the photoreceptors. This treatment aims to

directly under the fovea). Laser photocoag-

preserve vision.

ulation ablates the CNV. It is important that

Apart from photocoagulation and PDT, there

those cases that are likely to benefit from treat-

are other treatment modalities currently under

ment are first identified quickly. At the present

investigation. These include radiotherapy,

time, this entails photography of the fundus

thermal thermotherapy and drugs including

and fluorescein angiography, and infrared

triamcinolone, anercortave, and vascular

angiography with indocyanine green. Often

endothelial growth factor (VEGF) aptamers or

The Ageing Eye

153

antagonists, which are delivered via injections

Glaucoma

into the vitreous.

Practical measures can be taken in the man-

The various types of glaucoma have also been

agement of these patients to alleviate their

considered already, and the reader would realise

handicap. Telescopic lenses might be needed for

that glaucoma is simply the manifestation of a

reading or watching television and full consid-

group of diseases, each of which has a different

eration should be given to the question of blind

prognosis and treatment. Chronic simple, or

registration. It is important to explain the nature

open-angle, glaucoma is the important kind in

of the condition and prognosis to the patient.

the elderly because it often remains undiag-

This can alleviate considerable anxiety and fear

nosed. The physician and optometrist can play

of total blindness and help the patient come to

a vital part in the screening of this disease by

terms with the problem. In most cases, one eye

becoming familiar with the nature of glauco-

is involved first, the other following suit within

matous cupping of the optic disc. About 1% of

one to three years. The vision, as measured on

the population over the age of

55 years is

the Snellen chart, progressively deteriorates to

thought to suffer from chronic simple glaucoma

less than 6/60, but the peripheral field remains

and the figure could rise to as high as 30% in

unaffected so the patient is able to find his or

those over 75 years. In most instances, the treat-

her way about, albeit with some difficulty.

ment is simple but requires the co-operation

and understanding of the patient. The treatment

is preventative of further visual loss rather than

Cataract

curative. Chronic simple glaucoma is best

This common condition in the elderly eye has

managed in an eye unit on a long-term basis. By

already been considered, but it is important that

this means, the visual fields and intraocular

every physician can identify and assess the

pressure can be accurately monitored and the

density of a cataract in relation to the patient’s

treatment adjusted as required. More recently,

vision. The physician must realise the potential

the care of glaucoma patients is being shared

of cataract surgery in the restoration of vision.

between hospital units and selected (trained)

Cataract surgery is required only if vision is

optometrists in the community.

sufficiently reduced so far as to interfere with

the patient’s normal lifestyle. The contraindica-

Deformities of the Eyelids

tions for cataract surgery are few and even in

extreme old age the patient can benefit. Surgery

Both entropion and ectropion are common in

might be delayed if the patient has only one eye

the elderly and a complaint of soreness and

or if there is some other pathology in the eye,

irritation in the eyes as well as watering should

which is likely to affect the prognosis. The need

always prompt a careful inspection of the

for someone to assist the patient in the instil-

configuration of the eyelids. Entropion is

lation of eye drops and the domestic chores

revealed by pressing the finger down on the

during the postoperative period might require

lower lid so that the inverted lid becomes

some attention but is not a contraindication.

everted again to reveal the lash line. Sometimes

About one-third of the population aged over 70

entropion can be intermittent and not present at

years suffers from a cataract, but the quoted

the time of examination, but usually under these

figures vary according to the diagnostic criteria.

circumstances there is a tell-tale slight inversion

If an elderly person has an opaque lens, which

of the lid, which is made apparent by compar-

obscures any view of the fundus with the

ing the two sides. Ectropion is nearly always an

ophthalmoscope, and the pupil reacts quickly,

obvious deformity because of the easy visibility

then he or she is likely to do well after surgery.

of the reddened and everted conjunctiva, but

It is useful to remember that the reading vision

slight degrees of ectropion are less obvious. The

is usually fairly well preserved even when the

lower punctum alone can be slightly everted,

cataract is quite dense, and if the patient

causing a watering eye, and the symptoms might

is unable to read, there might be coincidental

be relieved by applying retropunctal cautery to

AMD, except if the cataract is of the posterior

the conjunctiva. Both ectropion and entropion

subcapsular type.

respond well to lid surgery and there is no

154

Common Eye Diseases and their Management

reason why geriatric patients should put up with

the continued discomfort and irritation when

a complete cure is readily available. These lid

deformities can recur sometimes and require

further lid surgery, but careful surgery in the

first instance should largely prevent this.

Temporal Arteritis

This condition, also known as giant cell arter-

itis, seen only in the elderly, can rapidly cause

total blindness unless it is treated in time. The

disease is more common than was originally

supposed but it is rare under the age of 50 years.

Medium-sized vessels, including the temporal

Figure 19.4. Giant cell arteritis: ischaemic optic neuropathy.

arteries, become inflamed and the thickening of

the vessel wall leads to occlusion of the lumen.

Histologically, the inflammatory changes are

characterised by the presence of foreign body

disease is suspected, a biopsy is essential and

giant cells and the thickening of the vessel wall

this should be done without delay. Treatment

is at the expense of the inner layers so that the

can be commenced immediately, sometimes

total breadth of the vessel might not be altered.

even before biopsy. However, it is advisable that

In early disease, the inflammatory changes tend

the lag between starting treatment and biopsy

to be segmental so that a single biopsy of a small

is as short as possible

(preferably less than

segment of the temporal artery does not always

two weeks). The symptoms disappear rapidly

reveal the diagnosis.

after administering systemic steroids, initially

Patients with temporal arteritis usually

in a high dose

(e.g., prednisolone

120 mg

present in the eye department with blurring of

per day), and the dosage is then reduced

vision or unilateral loss of vision. Typically,

rapidly according to the level of the ESR. Once

these symptoms are accompanied by headache

the ESR is down to normal levels, a mainten-

and tenderness of the scalp so that brushing the

ance dose of systemic steroids is continued,

hair might be painful. Often there is low-grade

if necessary for several months

(on average

fever and there can be aches and pains in the

18 months).

muscles and joints, as well as other evidence of

Temporal arteritis is recognised as a self-

ischaemia in the brain and heart. Scalp ulcera-

limiting condition. About one-quarter of all

tion and jaw claudication can occur. The blur-

patients are liable to become blind unless ade-

ring of vision is caused by ischaemia of the optic

quate treatment is administered and in some

nerve head or occasionally central retinal artery

instances, extraocular muscle palsies causing

occlusion. The diagnosis rests largely on finding

diplopia and ptosis can confuse the diagnosis.

a raised erythrocyte sedimentation rate (ESR),

For simplicity, one might summarise the disease

elevated C-reactive protein levels and a positive

by saying it causes headache in patients aged over

temporal artery biopsy in an elderly patient

70 years with an ESR over 70 and who require

with these symptoms. Palpation of the temporal

treatment with over 70 mg of prednisolone.

arteries reveals tenderness and sometimes

thickening and the absence of pulsation is a

Stroke

useful sign. Polymyalgia rheumatica is a syn-

drome consisting of muscle pain and stiffness

Patients who complain of visual symptoms after

affecting mainly the proximal muscles without

a stroke quite often have an associated homony-

cranial symptoms.

mous hemianopia and the association between

Inspection of the fundus in a patient with

hemiplegia and homonymous hemianopia

visual symptoms shows pallor and often

should always be borne in mind. A simple con-

swelling of the optic nerve head and narrowing

frontation field test might be all that is required

of the retinal arterioles (Figure 19.4). Once the

to confirm this in a patient with poor vision and

The Ageing Eye

155

normal fundi following a hemiplegic episode.

acuity of 6/6 and yet be unable to read the news-

The vertical line of demarcation between blind

paper. The picture can be further complicated

and seeing areas is well defined and can cut

by true dyslexia and the patient might admit to

through the point of fixation. Fortunately, the

being able to see the paper and yet be unable to

central 2° or 3° of the visual field are often

make any sense of it. Dyslexia might be sus-

spared. When there is so-called macular spar-

pected if other higher functions, such as speech,

ing, the visual acuity as measured by the Snellen

have been affected by the stroke. One of the fea-

chart can be normal. Patients tend to complain

tures of a homonymous hemianopic defect in

of difficulty in reading if the right homonymous

the visual field is the patient’s complete lack of

field is affected rather than the left, and

insight into the problem, so that even a doctor

although they might be able to read individual

might fail to notice it in himself. It is unusual for

words, they have great difficulty in following

a homonymous hemianopia to show any signs

the line of print. Thus, a patient with a right

of recovery, but once the patients understand

hemiplegia and a right homonymous hemi-

the nature of the handicap they can learn to

anopia might have normal fundi and visual

adapt to it to a surprising degree.

The Child’s Eye

atrophic. The foveal light reflex, that is the spot

How the Normal Features

of reflected light from the fovea, is absent or ill-

Differ from Those in an Adult

defined until the infant is four to six months old.

By six months the movement of the eyes should

At birth the eye is large, reaching adult size at

be well co-ordinated, and referral to an ophthal-

about the age of two years. One might expect

mologist is needed if a squint is suspected.

that before the eye reaches its adult size, it would

Once children learn to identify letters, at the age

be long-sighted, being too small to allow paral-

of four or five years, the Snellen chart can be

lel rays of light to be brought to a focus on the

employed to measure visual acuity, which by

retina. In actual fact, the immature lens is more

this age is normally 6/9 or 6/6. The Stycar test

globular and thus compensates for this by its

can be used for three- to four-year olds or

greater converging power. None the less, more

sometimes younger children and a similar level

than three-quarters of children aged under four

of visual acuity is seen as soon as the child is

years are slightly hypermetropic. The slight

able to co-operate with the test conditions.

change of refractive error that occurs as they

Stycar results tend to be slightly better than

grow compares with the more dramatic change

Snellen results when measured in the same

in axial length from 18 mm at birth to 24 mm in

child, perhaps because the Stycar test involves

the adult. The slight degree of hypermetropia

seeing a single letter rather than a line.

seen in childhood tends to disappear in adoles-

cence. Myopia is uncommon in infancy but

tends to appear between the ages of six and nine

How to Examine a Child’s Eye

years and gradually increases over subsequent

years. The rate of increase of myopia is maximal

The general examination of the eye has been

during the growing years and this can often be

considered already, but in the case of the child,

a cause of parental concern.

certain aspects require special consideration.

The iris of the newborn infant has a slate-grey

Before the age of three or four years, it might not

colour because of the absence of stromal pig-

be possible to obtain an accurate measure of the

mentation. The normal adult colouration does

visual acuity, but certain other methods that

not develop fully until after the first year. The

attempt to measure fixation are available. The

pupil reacts to light at birth but the reaction can

rolling ball test measures the ability of the child

be sluggish and it might not dilate effectively in

to follow the movement of a series of white

response to mydriatic drops. The fundus tends

balls graded into different sizes. Another test

to look grey and the optic disc somewhat pale,

makes use of optokinetic nystagmus, which can

deceiving the uninitiated into thinking that it is

be induced by making the child face moving

157

158

Common Eye Diseases and their Management

vertical stripes on a rotating drum. The size of

examination under anaesthesia. A casualty

the stripes is then reduced until no movement

situation, which occurs from time to time, is

of the eyes is observed. In practice, a careful

when a child is brought in distressed with a sus-

examination of the child’s ability to fix a light,

pected corneal foreign body or perhaps a per-

and especially the speed of fixation, is helpful.

forating injury. Here, it is simplest to wrap the

The behaviour of the child can also be a helpful

patient in a blanket so as to restrain both arms

guide, for example the response to a smile or

and legs and then examine the cornea by

the recognition of a face. Sometimes grossly

retracting the lids with retractors. Particular

impaired vision in infancy is overlooked or

care must be taken when examining an eye

interpreted as a psychiatric problem, but such

with a suspected perforating injury in view of

an error can usually be avoided by careful

the risk of causing prolapse of the contents of

ophthalmological examination. The reaction of

the globe. Any ophthalmological examination

the pupils is an essential part of any visual

demands placing one’s head close to that of the

assessment. One of the difficulties in examining

patient and this can alarm a child unless it is

children is that they are rarely still for more than

done sufficiently slowly and with tact. It is some-

a few seconds at a time, and any attempts at

times helpful to make the child listen to a small

restraint usually make matters worse. Before

noise made with the tongue or ophthalmoscope

starting the examination, it is useful to gain the

to ensure at least temporary stillness.

child’s confidence by talking about things that

might interest him or her, not directly but in

conversation with the parent. In fact, it is

Screening of Children’s Eyes

sometimes better to ignore the anxious child

deliberately during the first few minutes of the

In an ideal world, all children’s eyes would be

interview. Once the young patient has summed

examined at birth by a specialist and again at six

you up, hopefully in a favourable light, then a

months to exclude congenital abnormalities and

gentle approach in a quiet room is essential for

amblyopia.This is rarely achieved,although most

best co-operation. The cover test can only be

children in the UK are examined by a nonspe-

performed well under such conditions and once

cialist at these points. Most children are also

this has been done the pupils and anterior part

screened routinely in school at the age of six

of the eye can be examined, first with a hand

years, and any with suspected poor vision are

lens but if possible with the slit-lamp micro-

referred for more detailed examination. A

scope. Fundus examination and measurement

further examination is often conducted at the age

of any refractive error demand dilatation of

of nine or ten years and again in the early teens.

the pupils and paralysis of accommodation.

The commonest defect to be found is refractive

Cyclopentolate 1% or tropicamide 1% are both

error,that is simply a need for glasses without any

used in drop form for this purpose. The indirect

other problem. The ophthalmological screening

ophthalmoscope is a useful tool when examin-

is usually performed by a health visitor in the

ing the neonatal fundus, the wide field of view

preschool years and a school nurse for older chil-

being an advantage in these circumstances. If

dren. Screening tends to include measurement of

the infant is asleep in the mother’s arms, this

visual acuity alone but checking any available

can be beneficial because it is a simple matter

family history of eye problems would be helpful.

to raise one eyelid and peer in without waking

When there is a difference in the visual acuity of

the patient. In the case of children between the

each eye, the screener should suspect the possi-

ages of three and six years, fundus examination

bility of a treatable medical condition rather than

can be more easily achieved by sitting down and

just a refractive error. A test of colour vision

asking the standing patient to look at some spot

should also be included in the screening pro-

or crack on the wall while the optic disc is

gramme for older children and this can be con-

located. On some occasions the child has

veniently done using the Ishihara plates. It is

become too excited or anxious to allow a proper

worth remembering that colour blindness affects

examination and here one might have to decide

8% of men and 0.4% of women and it might have

whether it is reasonable to postpone the exam-

important implications on the choice of a job. It

ination for a week or whether the matter seems

is also equally important to realise that colour

urgent enough to warrant proceeding with an

blindness can vary considerably in degree and

The Child’s Eye

159

can often be so mild as to cause only minimal

head tilt and especially if the lid covers the

inconvenience to the sufferer.

visual axis. See Chapter 5 for more information

about eyelid deformities.

Congenital Eye Defects

Congenital Nystagmus

Lacrimal Obstruction

Children with congenital nystagmus are usually

brought to the department because their parents

The watering of one or both eyes soon after birth

have noticed that their eyes seem to be continu-

is a common problem. The obstruction is nor-

ously wobbling about. Such abnormal and per-

mally at the lower end of the nasolacrimal duct,

sistent eye movements might simply occur

where a congenital plug of tissue remains. Infec-

because the child cannot see (sensory nystag-

tion causing purulent discharge can be treated

mus) or they might be caused by an abnormality

effectively by the use of antibiotic drops.

of the normal control of eye movements (motor

Although these should clear the unpleasant dis-

nystagmus). It is important to distinguish con-

charge, the eye continues to water as long as the

genital nystagmus from acquired nystagmus

tear duct is blocked. The mother can be shown

because of a space-occupying intracranial lesion.

how to massage the tear sac. This manoeuvre

causes mucopurulent material to be expressed

Sensory Congenital Nystagmus

from the lower punctum when there is a block-

age and can be used as a diagnostic test. If

The roving eye movements are described as

carried out regularly, this helps to relieve the

pendular, the eyes tending to swing from side to

obstruction. In most cases, spontaneous relief

side. Examination of the eyes reveals one of the

of the obstruction occurs, but if this does not

various underlying causes: congenital cataract,

occur after about six to nine months, probing

albinism, aniridia, optic atrophy or other causes

and syringing of the lacrimal passageway under

of visual impairment in both eyes. A special

general anaesthesia is an effective procedure,

kind of retinal degeneration known as Leber’s

which can be done as a day case. It is important

amaurosis can present as congenital nystagmus.

to remember that a watering eye can be caused

The condition resembles retinitis pigmentosa,

by excessive production of tears as well as inade-

being a progressive degeneration of the rods

quate drainage, and in a child, a corneal foreign

and cones, and occurs at a young age. It tends to

body or even congenital glaucoma might be mis-

lead to near blindness at school age. Patients

taken for lacrimal obstruction by the unwary.

with congenital nystagmus usually need to be

examined under general anaesthesia, and elec-

Epicanthus

troretinography (a technique that can detect

retinal degenerations at an early stage) should

This relatively minor defect at the medial

be performed at the same time.

canthus is formed by a bridge of skin running

vertically. This is seen normally in some orien-

Motor Congenital Nystagmus

tal races. In Europeans it usually disappears as

the bridge of the nose develops, but its impor-

The exact cause of this type of nystagmus is

tance lies in the fact that it can give the mis-

usually never ascertained but a proportion of

leading impression that a squint is present.

such cases show recessive inheritance. Other

Severe epicanthus can be repaired by a plastic

abnormalities might be present, such as mental

procedure on the eyelids.

deficiency, but many children are otherwise

entirely normal. The nystagmus tends to be

jerky, with the fast phase in the direction of gaze

Ptosis

to the right or left. The distance vision is usually

Congenital drooping of the eyelid can be uni-

impaired to the extent that the patient might

lateral or bilateral and sometimes shows a

never be able to read a car number plate at

dominant inheritance pattern. The ptosis can be

23 m. The near vision, on the other hand, is

associated with other lid deformities. Referral

usually good, enabling many patients with this

for surgery is indicated if there is significant

problem to graduate through university.

160

Common Eye Diseases and their Management

Spasmus Nutans

be suspected if the iris is seen to be tremulous.

This strange wobbling movement of the iris used

This term refers to a type of pendular nystag-

to be seen in the old days after cataract surgery

mus, which is present shortly after birth and

without an implant, but it is now still seen after

resolves spontaneously after one or two years.

injuries to the eye and signifies serious damage.

Like other forms of congenital nystagmus, it can

Congenital subluxation of the lens is seen as

be associated with head nodding.

part of Marfan’s syndrome (congenital heart

disease, tall stature, long fingers, high arched

Albinism

palate). Congenital glaucoma has already been

discussed in the chapter on glaucoma; it can be

The lack of pigmentation might be limited to

inherited in a dominant manner and is the result

the eye, ocular albinism, or it might be gener-

of persistent embryonic tissue in the angle of the

alised. The typical albino has pale pink skin and

anterior chamber. When the intraocular pres-

white hair, eyebrows and eyelashes. There is

sure is raised in early infancy, the eye becomes

often congenital nystagmus. The optic fundus

enlarged, producing buphthalmos (“bull’s eye”).

appears pale and the choroidal vasculature is

This enlargement with raised pressure does not

easily seen. The iris has a grey-blue colour but

occur in adults.

the red reflex can be seen through it, giving the

iris a red glow. Albinism is inherited in a reces-

sive manner and can be partial or complete.

Congenital Cataract

Albinos need strong glasses to correct their

The lens can be partially or completely opaque

refractive error, which is usually myopic astig-

at birth. Congenital cataract is often inherited

matism. Dark glasses are also usually required

and can be seen appearing in a dominant

because of photophobia. Tinted contact lenses

manner together with a number of other con-

can sometimes be helpful.

genital abnormalities elsewhere in the body. The

condition might also be acquired in utero, the

Structural Abnormalities

best known example of this being the cataract

caused by rubella infection during the first

of the Globe

trimester of pregnancy: remember the triad of

There are many different developmental abnor-

congenital heart disease, cataract and deafness

malities of the globe but most of these are for-

in this respect. Minor degrees of congenital

tunately rare. Coloboma refers to a failure of

cataract are sometimes seen as an incidental

fusion of the foetal cleft of the optic cup in the

finding in an otherwise normal and symptom-

embryo. Coloboma of the iris is seen as a

less eye. The nature of the cataract usually helps

keyhole-shaped pupil and the defect can extend

with the diagnosis. The lens fibres are laid down

into the choroid, so that the vision might be

from the outside of the lens throughout life. If

impaired. Inspection of the fundus reveals an

the opaque lens fibres are laid down in utero,

oval white area extending inferiorly from the

this opaque region can remain in the centre of

optic disc. Children can be born without an eye

the lens. Only when the cataract is thick does it

(anophthalmos) or with an abnormally small

present as a white appearance in the pupil and

eye (microphthalmos). It is always important to

often it is difficult to detect it. It is important to

find out the full extent of this type of abnor-

examine the red reflex and see whether the

mality and if the mother has noticed something

darker opaque lens fibres show up. The surgeon

amiss in the child’s eye, referral to a paediatric

has to decide whether the vision of the child has

ophthalmologist is required without delay.

been significantly affected and unless the

Often a careful discussion of the prognosis with

cataracts are dense it might be better to wait

both parents is needed.

until the school years approach in order to

obtain a more accurate measure of the vision.

Sometimes the vision can turn out to be sur-

Aniridia

prisingly good with apparently dense cataracts.

Aniridia (congenital absence of the iris) can be

The surgical technique is similar to that for

inherited as a dominant trait and can be asso-

cataract surgery in the adult. Before the intro-

ciated with congenital glaucoma. The lens can be

duction of lens implants, the risk of developing

subluxated or dislocated from birth. This might

a retinal detachment in later life was high in

The Child’s Eye

161

these patients. When the cataract is unilateral,

early childhood. The word “amblyopia” means

this presents a special case because the affected

blindness and tends to be used rather loosely by

eye tends to be amblyopic, thus preventing a

ophthalmologists. It is most commonly used to

useful surgical result.

refer to amblyopia of disuse (“lazy eye”) but it

is also used to refer to loss of sight caused by

drugs. Amblyopia of disuse is common and

Other Eye Conditions

some patients even seem unaware that they have

any problem until they suffer damage to their

in Childhood

sound eye. This weakness of one eye results

when the image on the retina is out of focus or

Abnormalities of Refraction

out of position for more than a few days or

months in early childhood or, more specifically,

Nowadays children whose vision is impaired

below the age of eight years. Amblyopia of

because they need a pair of glasses are usually

disuse, therefore, arises as the result of a squint

discovered by routine school testing of their

or a one-sided anomaly of refraction, or it can

visual acuity. They might also present to the

occur as the result of opacities in the optical

doctor because the parents have noticed them

media of the eye. A corneal ulcer in the centre

screwing up their eyes or blinking excessively

of the cornea of a young child can rapidly lead

when doing their homework. Some children can

to amblyopia. Once a clear image has been pro-

tolerate quite high degrees of hypermetropia

duced on the retina, either by the wearing of

without losing visual acuity simply by exercis-

spectacles or other treatment, the vision in the

ing their accommodation, and unless there

weak eye can be greatly improved by occluding

appears to be a risk of amblyopia or squint,

the sound eye. The younger the patient, the

glasses might not be needed. By contrast, even

better are the chances of improving the vision

slight degrees of myopia, if both eyes are

by occlusion. Beyond the age of eight years it is

affected, can interfere with school work. Myopia

unlikely that any significant improvement can

does not usually appear until between the ages

be achieved by this treatment and, by the same

of five and 14 years, and most commonly at

token, it is unlikely that amblyopia will appear

about the age of 11.

after the age of eight years. An adult could suffer

total occlusion of one eye for several months

Squint

without experiencing any visual loss in the

occluded eye.

This exceedingly common inherited problem of

childhood has already been considered, but it is

worth summarising some of the main features.

Leucocoria

All cases of squint require full ophthalmological

This term means “white pupil” and it is an

examination because the condition can be asso-

important sign in childhood. There are a

ciated with treatable eye disease,most commonly

number of conditions that can produce this

amblyopia of disuse. There is no reason why any

effect in early childhood. The important thing to

patient, child or adult, should suffer the indignity

realise is that if a mother notices “something

of looking “squint eyed” because the eyes can be

white” in the pupil, the matter must never be

straightened by surgery. In spite of this, it is not

overlooked and requires immediate investiga-

always possible to restore the full simultaneous

tion. The differential diagnosis includes con-

use of the two eyes together (binocular vision).

genital cataract, opaque nerve fibres in the

In general, the earlier in life that treatment is

retina, retinopathy of prematurity, endophthal-

started, the better the prognosis.

mitis, some rare congenital abnormalities of

the retina and vitreous and, not common but

Amblyopia of Disuse

most important, retinoblastoma.

This has been defined as a unilateral impair-

ment of visual acuity in the absence of any other

Retinopathy of Prematurity

demonstrable pathology in the eye or visual

pathway. This rather negative definition fails to

In the early

1940s, premature infants with

explain that there is a defect in nerve conduc-

breathing difficulties began to be treated with

tion because of inadequate usage of the eye in

oxygen, and 12 years elapsed before it was

162

Common Eye Diseases and their Management

realized that the retinopathy seen in premature

important examination of the cornea. When the

children was caused by this treatment. During

disease is suspected, the infant should be admit-

the course of oxygen therapy in a premature

ted to hospital and treated with penicillin drops

infant, the retinal vessels become narrowed and

every hour. Diagnosis is achieved by taking a

the optic disc becomes pale. When the oxygen

conjunctival culture before treatment is started

treatment is stopped, the retinal vessels become

and by looking for the inclusion bodies of the

engorged and new vessels grow from the

chlamydial virus in a smear. The history of

peripheral arcades in the extreme periphery of

infection in the parents needs to be explored

the fundus. This growth of abnormal vessels

and managed by a genitourinary specialist.

leads to vitreous haemorrhage, retinal detach-

ment and fibrosis of the retina. The infant can

Uveitis

rapidly become blind, although some are mini-

mally affected. The management of the con-

Uveitis is rare in childhood; it can take the form

dition now involves screening of those children

of choroiditis, sometimes shown to be because

at risk and monitoring of blood oxygen levels.

of toxoplasmosis or toxocara, or the form of

When the condition occurs, treatment with

anterior uveitis sometimes associated with

cryotherapy to the peripheral retina has been

Still’s disease. The management of these cases is

shown to be beneficial. Now that children are

similar to that of the adult, but recurrences can

being born at an earlier and earlier stage, it

result in severe visual loss in spite of treatment.

seems that extreme prematurity runs the risk of

blindness from this cause even in the absence of

supplementary oxygen.

Optic Atrophy

One must be rather wary about the diagnosis of

Ophthalmia Neonatorum

optic atrophy in young children because the

optic discs tend to look rather pale in normal

It is important to realise that in the early part of

individuals. Occasionally, unilateral visual loss

this century, a large proportion of the inmates

with or without a squint is found to be associ-

of blind institutions had suffered from oph-

ated with pallor of the disc on one side.

thalmia neonatorum. The disease affects pri-

Confirmed optic atrophy, either unilateral or

marily the conjunctiva and cornea and is the

bilateral, requires a full neurological investig-

result of infection by organisms resident in the

ation. The causes of optic atrophy in childhood

maternal birth passage. The gonococcus was

are numerous but the important ones can be

the most serious cause of blindness but a

listed as follows:

number of other bacteria have been incrimi-

• Causes of optic atrophy without systemic

nated, including staphylococci, streptococci and

disease include:

pneumococci. It has also been shown that

chlamydial infection of the genital tract can

- hereditary optic atrophy

lead to the same problem, as can infection by

- drug toxicity.

the herpes simplex virus. The blindness that

• Causes of optic atrophy with systemic

resulted from this condition was so serious that

disease include:

any excessive discharge from the eyes has been

- glioma of chiasm and craniopharyngioma

a notifiable disease in this country since 1914.

Ophthalmia neonatorum is caused by unhy-

- post meningitic

gienic conditions at birth and its relative rarity

- post traumatic after head injury

nowadays is because of the fact that midwives

- hydrocephalus

are trained to screen for the condition. Bacter-

- cerebral palsy

ial conjunctivitis usually occurs between the

- disorders of lipid metabolism.

second and fifth day after birth, whereas

chlamydial infection tends to occur a little later,

between the sixth and tenth day. Purulent or

Juvenile Macular Degeneration

mucopurulent discharge is evident and the

eyelids can become tense and swollen so that it

This is a rare cause of progressive visual loss in

is difficult to open them and carry out the all-

children, the diagnosis being made perhaps

The Child’s Eye

163

once in a lifetime at primary care level. For this

reveals the diagnosis. In Von Recklinghausen’s

reason, the diagnosis can easily be missed, esp-

neurofibromatosis, multiple neuro-fibromata

ecially as the patient finds difficulty in reading

are seen on the skin, and the eyelids may be

but no difficulty in walking around. Some cases

enlarged and distorted. Gliomata can develop in

show dominant inheritance and so the family

the optic nerves and scattered pigment “cafe au

history can be important.

lait” patches are seen in the skin. Brown nodules

can be seen on the iris. In tuberose sclerosis,

mental deficiency and epilepsy are associated

with a raised nodular rash on the cheeks and

The Phakomatoses

mulberry-like tumours in the optic fundus. Von

The three conditions - Von Recklinghausen’s

Hippel-Lindau disease presents to the ophthal-

neurofibromatosis, tuberose sclerosis (Bourn-

mologist as angiomatosis retinae. Vascular

ville’s disease) and Von Hippel-Lindau disease -

tumours appear in the peripheral retina,

are classed together under this name. They all

which can leak and expand and lead to detach-

involve the eye but might not become evident

ment of the retina. Similar tumours can be

until later life. Often, examination of the eye

present intracranially.

Systemic Disease and the Eye

longer to show eye changes than those with a

Diabetes

late onset.

Diabetes mellitus affects 1-2% of the UK popu-

Although diabetic retinopathy is the most

lation. The disease is more prevalent in other

serious ocular complication, the eye can be

countries. Diabetic retinopathy is the common-

affected in a number of other ways and it is con-

est cause of legal blindness in patients between

venient to consider the various ocular manifes-

the age of 20 and 65 years such that about 1000

tations of diabetes in an anatomical manner,

people are registered blind from diabetes per

beginning anteriorly.

year in the UK. The management of diabetic eye

disease has improved greatly over the past 20

Eyelids

years so that much of the blindness can now be

prevented. In spite of this, most general prac-

It is usual to check the urine of patients pre-

titioners are aware of tragic cases of rapidly pro-

senting with recurrent styes but in practice, it is

gressive blindness in young diabetics. The more

unusual for diabetes to be diagnosed in this way.

serious manifestations of diabetes in the eye

Xanthelasma of the eyelids is said to be slightly

tend to affect patients in the prime of life. The

more common in diabetics.

tragedy is even greater when one considers that

this blindness is largely avoidable.

Ocular Movements

Diabetes is, therefore, the most important sys-

temic (noninfective) disease that gives rise to

Elderly diabetic patients are more prone to

blindness. Many diabetics remain free of eye

develop transient third and sixth cranial nerve

problems, but a diabetic is

25 times more

palsies than nondiabetics of the same age group.

likely to become blind than other members of

Sometimes isolated third nerve palsy can be

the population.

painful and the pupil is spared. A fasting blood

When taking an eye history from diabetic

sugar might be required in patients presenting

patients, it is especially important to note the

with isolated third nerve palsies. Hypertension

duration of the diabetes and the age of onset,

and arteriosclerosis need exclusion.

because the incidence of diabetic retinopathy is

most related to the duration of diabetes. Other

Cornea and Conjunctiva

risk factors are listed in Table 21.1.

Diabetic retinopathy is extremely rare under

Some diabetics have microcirculatory changes,

the age of ten years; it does not usually appear

for example conjunctival vascular irregularity

until the disease has been present for some

and dilatation. Corneal ulcers in diabetics can

years. Juvenile-onset diabetics usually take

prove particularly troublesome. Minor trauma

165

166

Common Eye Diseases and their Management

Table 21.1. Risk factors for diabetic retinopathy.

involves the anterior chamber angle. If left

untreated, few eyes with rubeosis iridis retain

•

Age

•

Duration of diabetes

useful sight. The iris should be examined care-

•

Smoking

fully before pupillary dilation.

•

Hypertension

•

Poor diabetic control

Lens

•

Hyperlipidaemia

•

Renal impairment

It was mentioned in an earlier chapter that

•

Pregnancy

diabetics tend to develop senile cataracts at an

earlier stage than normal. Once developed,

cataracts also progress more quickly in diabet-

to the cornea can lead to the formation of indo-

ics compared with nondiabetics. In addition, a

lent chronically nonhealing or infected ulcers,

rapidly advancing type of cataract is seen in

which respond slowly to intensive treatment

young poorly controlled patients. This is a true

with local antibiotics. Inadequate treatment can

diabetic cataract. This cataract is bilateral and

lead to endophthalmitis and loss of the eye. This

consists of snowflake posterior or anterior opac-

problem occurs especially in diabetics with

ities, matures rapidly and is similar to the rare

severe vascular disease and typically in a patient

cataract seen in starvation from whatever cause.

who has had to have a gangrenous leg removed.

The routine testing of urine of patients with

cataracts produces a good return of positive

Anterior Chamber

results, making this an essential screening test.

It was also mentioned in a previous chapter

A particular kind of iritis is occasionally seen in

that the refractive power of the lens might

diabetics after cataract surgery when there is a

change in response to a rise in the blood sugar

severe plastic reaction. It is important that such

level. This results from increased hydration of

cases are treated adequately to prevent the

the lens in patients with high uncontrolled

development of posterior synechiae, which will

blood sugar levels. Undiscovered diabetics quite

make subsequent fundal examination difficult.

often become short-sighted because of this so-

Many surgeons consider it advisable, therefore,

called index myopia. They can then obtain some

to use mydriatic drops (cyclopentolate) after

distance glasses and subsequently consult their

cataract surgery in diabetics.

doctor, who treats their diabetes. By this time

the glasses are made and, of course, turn out to

Iris

be unsatisfactory, because the index myopia

can improve with treatment. In some instances

The iris itself often shows degenerative changes

index myopia proves irreversible, being the first

in longstanding diabetics. The pupil can react

sign of cataract formation.

sluggishly and fail to dilate widely after the

instillation of mydriatic drops. The surgeon can

appreciate that pigment is easily lost from the

iris when it is handled, and it is interesting that

a characteristic vacuolation of the pigment

epithelium lining the posterior surface of the

iris is seen in histological sections. When dia-

betes seriously interferes with the circulation of

the eye, the iris can become covered on its anter-

ior surface by a fibrovascular membrane. To the

naked eye, the iris takes on a pinkish colour, but

examination with the slit-lamp biomicroscope

or a magnifying lens soon reveals the minute

irregular blood vessels on its surface. The

appearance is known as “rubeosis iridis” or

neovascularisation of the iris (Figure 21.1). Neo-

vascular glaucoma occurs once the rubeosis

Figure 21.1. Rubeosis iridis.

Systemic Disease and the Eye

167

Retina and Vitreous

Diabetic retinopathy is the most serious compli-

cation of diabetes in the eye and often reflects

severe vascular disease elsewhere in the body.

There are two kinds of diabetic retinopathy:

background and proliferative. Background re-

tinopathy is common when diabetes has been

present for some years and is less of a threat to

the sight than the proliferative variety. Diabetic

maculopathy is a special form of retinopathy that

can occur with either background or prolifera-

tive disease. It is important that the doctor is able

to recognise diabetic retinopathy and especially

important that he or she should be familiar with

the warning signs that indicate proliferative

changes and significant maculopathy.

Diabetic retinopathy is essentially a small

vessel disease affecting the retinal precapillary

arterioles, capillaries and venules. The larger

vessels can be involved. The vascular disease can

take the form of vascular leakage or closure,

with resultant ischaemia, or both.

Background Retinopathy

There are usually no ophthalmic symptoms

initially, but inspection of the fundi of most dia-

betics who have had the disease for ten years or

Figure 21.2.

Background diabetic retinopathy. a Early: micro-

more reveals, at first, a few microaneurysms.

aneurysms and haemorrhages. b Severe: extensive haemor-

They are often on the temporal side of the

rhages, cotton-wool spots and venous dilatation.

macula but often scattered over the posterior

pole of the fundus (Figure 21.2). These might

come and go over months and the overall

picture could be unchanged for several years.

are greyish-white with poorly defined fluffy

The vision is not affected unless the micro-

edges. Histological examination of diseased

aneurysms are clustered round the macular

retina has shown areas of capillary closure and

region and leak fluid, resulting in macular

capillary microaneurysms. The vessel walls have

oedema. Exudates are also seen and these tend

thickened basement membranes and loss of

to form rings around areas of diseased vessels,

mural cells (pericytes) (Figure 21.3).

although only one part of the ring might be

present at any given point. These are yellowish-

The Preproliferative Stage

white deposits with well-defined edges, which

are the result of precipitation of leaked lipo-

Proliferative retinopathy is typically seen in

proteins from diseased blood vessels. Capillary

poorly controlled diabetics

(usually type I

dilatation is a more subtle sign of diabetic

diabetes). The situation can become bad quickly

retinopathy. Haemorrhages, which can be small

and it is important to be able to recognise the

(“dot”) or large blot, result from the venous end

warning signs, which occur before proliferation.

of capillaries and are in the deep retina. Flame-

There are three of them: a large number of dark

shaped haemorrhages can also occur in the

blot haemorrhages, irregular calibre and dila-

nerve fibre layer. “Cotton-wool” spots represent

tation of the retinal veins (beading) and finally,

axoplasmic accumulation adjacent to micro-

the presence of intraretinal microvascular

infarction of the retinal nerve fibre layer. They

abnormalities. These warning signs can herald

168

Common Eye Diseases and their Management

Figure 21.3. Trypsin digest of retina showing microaneursyms

and loss of some mural cells.

the appearance of the retinal or optic discs new

Figure 21.4. Proliferative diabetic retinopathy.

vessels, which should not be confused with

normal disc capillaries or with widened collat-

eral vessels. Approximately 50% of eyes with

Diabetic Maculopathy

preproliferative changes will progress to pro-

This is the commonest cause of visual impair-

liferative disease within one year.

ment in diabetics. It occurs more commonly in

type II diabetics. Three types of maculopathy

Proliferative Retinopathy

are known and these can occur in isolation or

in combination with each other. The three types

Proliferative diabetic retinopathy occurs in 5%

are:

of all diabetics. Younger-onset diabetics have an

increased risk of the disease after 30 years. Until

•

Focal caused by focal leakage from a micro-

recently 50-70% of cases of proliferative diabetic

aneurysm or dilated capillaries and sur-

retinopathy became blind within five years.

rounding exudates are seen (Figure 21.5).

Proliferative diabetic retinopathy is charac-

•

Diffuse oedema caused by diffuse leakage

terised by the development of new blood vessels

from dilated capillaries at the posterior

(neovascularisation) on the optic nerve head

or the retina (Figure 21.4). These occur as a

response to retinal ischaemia. These new vessels

can appear as small tufts, which ramify irreg-

ularly. They might be flat initially but enlarge

and move forward into the vitreous cavity as

they grow. Once the new vessels form and

grow, there is increased risk of an acute pre

retinal or vitreous haemorrhage. This is a

significant threat to vision because the vitreous

haemorrhages can become recurrent or dense,

preventing any meaningful examination and

treatment. Retinal fibrosis, traction retinal

detachment and neovascular glaucoma can

occur at a later stage.

It is important to appreciate that proliferative

retinopathy can be quite severe before the

patient notices anything and the situation

might have to be explained carefully to him

or her.

Figure 21.5. Focal maculopathy.

Systemic Disease and the Eye

169

pole of the eye. Retinal oedema is diffuse

and can be associated with microaneur-

ysms and few haemorrhages but exudates

are absent (Figure 21.6).

• Ischaemic maculopathy is caused by

closure of the perifoveal and surrounding

vascular network. In addition to diffuse

oedema, several dark haemorrhages might

be present

(Figure

21.7a). Fluorescein

angiography might be required to confirm

the ischaemia and determine its severity

(Figure 21.7b).

Treatment

Control of Diabetes

This aspect of treatment might seem self-

evident but in the past the value of careful

control has not always been fully recognised.

Some patents have the impression that eye prob-

lems develop anyway if the diabetes has been

Figure 21.7. Ischaemic maculopathy: a colour photograph;

b fluorescein angiogram.

present long enough. Nothing could be further

from the truth. Control of the diabetic state

needs to be sustained. Control or elimination

of the known risk factors (see Table 21.1) is

also important in reducing the severity of

diabetic retinopathy.

Laser Photocoagulation

The use of a focused light beam to cauterise the

retina has been practiced for several years and

the value of this treatment has been confirmed

Figure 21.6. Macular oedema: a colour photograph; b fluores-

by extensive clinical trials for both proliferative

cein angiogram of eye in a showing diffuse and cystoid

disease and some types of maculopathy. The

oedema.

exact mode of action is not known but it has

170

Common Eye Diseases and their Management

been suggested that the photocoagulation of

that it is now possible to remove a persistent

ischaemic areas prevents the release of some, as

vitreous haemorrhage and to divide or remove

yet unidentified, vasoformative factor in prolif-

fibrous tissue,even from the surface of the retina,

erative disease. The treatment must be applied

and relieve traction retinal detachment. Vitrec-

promptly in the early proliferative stage or

tomy for vitreous haemorrhage tends to be per-

sometimes before. About 2500-3000 burns (of

formed sooner these days because of the relative

500 mm spot size) are needed in an eye with pro-

safety of the technique. It can be combined with

liferative retinopathy. This might require several

intraoperative laser photocoagulation.

treatment sessions (Figure 21.8). The laser treat-

ment of focal and diffuse maculopathy involves

Prognosis

application of small number of burns (of 100-

200 mm spot size) to the leaking area, avoiding

A better understanding of diabetic retinopathy

the fovea. Ischaemic maculopathy generally is

has resulted from the use of more accurate

less amenable to laser treatment.

methods of investigation, especially fluorescein

angiography, and also the routine use of indirect

ophthalmoscopy and slit-lamp microscopy.

Glaucoma Surgery

Serial fundus photography and the use of ultra-

Drainage surgery might be needed if neovascu-

sound have also been important. This better

lar glaucoma is not controlled by medical

understanding and modern technology have led

means. Rubeosis iridis initially requires pan-

to more effective treatment so that the more

retinal laser photocoagulation. Chronic simple

severe ocular complications are now largely

glaucoma can also be more common in diabet-

avoidable. Blindness tends to be limited to those

ics. Drainage surgery in these cases is less suc-

cases where social or other circumstances make

cessful than in nondiabetics. Special measures

management difficult. Patient education is vital

need to be taken to avoid failure.

in order to maintain continuing improvement

in visual prognosis for diabetics. After 20 years,

75% of diabetics will develop some form

Vitreo-retinal Surgery

of retinopathy. About 70% of patients with pro-

There have been dramatic advances in the tech-

liferative retinopathy will progress to blindness

nical side of vitreous surgery in recent years so

if untreated in five years.

Thyroid Eye Disease

Dysthyroid eye disease is an autoimmune

disease in which the manifestations can be

notable in the hyperthyroid, euthyroid or

hypothyroid phase. Although the ophthalmic

features of thyroid disease are often diagnosed

in the hyperthyroid phase, a significant number

of patients may be euthyroid (i.e., have no other

evidence of thyroid disease) or less often

hypothyroid at the time of detection of the

eye changes. Thus, the ophthalmic disease

might precede, be coincidental or follow the

systemic manifestations.

Grave’s disease is a term used to describe the

most common form of hyperthyroidism that

has an autoimmune basis. Hyperthyroidism

can arise from other conditions, for example

thyroid tumour or pituitary dysfunction. It

Figure 21.8. Panretinal laser photocoagulation in proliferative

usually affects women between 20 and 45 years.

diabetic retinopathy.

Usually it is characterised by goitre, infiltrative

Systemic Disease and the Eye

171

Table 21.2. The 13 possible eye signs of thyroid disease.

•

Proptosis

•

Raised intraocular pressure when looking up

•

Lid lag

•

Lid retraction

•

Lid swelling

•

Chemosis

•

Conjunctival congestion

•

Double vision

•

Exposure keratitis

•

Corneal ulceration

•

Optic disc swelling

•

Impaired visual acuity

•

Constriction of visual field

ophthalmopathy, thyroid acropathy (clubbing)

and pretibial myxoedema. When these ophthal-

mic changes occur in isolation, the condition is

described as ophthalmic Graves’ disease.

Figure 21.9. Dysthyroid eye disease: eyelid retraction.

The systemic features of hyperthyroidism

include weight loss, high pulse rate, poor toler-

ance of warm weather and fine tremor. The eye

•

Proptosis. Lid retraction can give the false

signs of thyroid disease are eyelid retraction

impression of proptosis but measurement

and lid lag, puffiness of the eyelids, chemosis,

of the position of the globe in relation to

proptosis, exposure keratitis, double vision from

the bony orbit can be achieved by means of

muscle involvement and optic neuropathy

an exophthalmometer. Any relative pro-

(Tables 21.2 and 21.3).

trusion can thus be measured for future

reference. Dysthyroid disease is the com-

• Lid retraction. Eyelid drawn up slightly,

monest cause of unilateral or bilateral

more on one side than the other. Reveals

proptosis. Forward protrusion of the globe

white sclera above corneoscleral junction

can lead to severe exposure keratitis

(Figure 21.9).

demanding urgent attention.

• Lid lag. When instructed to follow a pencil

•

Exposure keratitis. Punctate staining with

as it moves downwards, the upper lid

fluorescein across the lower part of the

appears to lag behind the rotation of the

cornea is characteristic and caused by inad-

eye, revealing more of the white above.

equate closure of the retracted upper lid.

The upper lid shows jerky movements as

the eye rotates smoothly down.

• Lid swelling. Puffiness of the eyelids can be

present (Figure 21.10).

• Chemosis. This means conjunctival oedema.

To the naked eye it appears as though

the eyes are brimming with tears, and the

expression “the tear that never drops” is

sometimes used. When severe, the con-

junctiva overhangs the lower lid margin.

Table 21.3. Routine tests for thyrotoxicosis.

•

Serum thyroxine (T4)

•

Thyroid autoantibodies

•

T3 assay

Figure 21.10. Dysthyroid eye disease: lid oedema.

172

Common Eye Diseases and their Management

•

Limitation of extraocular muscle action.

there is no response between 24 h and 48 h, sur-

The muscles become infiltrated and thick-

gical decompression of the orbits is required. If

ened, producing a characteristic appear-

double vision persists beyond the acute stage,

ance on computed tomography (CT) scan,

extra-ocular muscle surgery can be helpful and

which helps to distinguish this form from

operations have also been designed to deal with

other causes of diplopia. The main restric-

lid retraction.

tion of movement is due to infiltration,

then subsequently tethering of the inferior

recti with limitation of upwards gaze. The

Hypertension

resulting pressure on the globe can cause

the intraocular pressure to rise on looking

Although the effects of raised blood pressure on

up and this has been used as a diagnostic

the appearance of the fundus of the eye were

test. The other extraocular muscles are

recognised in the nineteenth century, the nature

involved less frequently.

of the detailed changes is still disputed. Certain

•

Optic nerve compression. This condition

characteristic features, such as the nipping of

occurs in only 5% of cases of thyroid eye

the veins at arteriovenous crossings, narrowing

disease. However, it is important because of

of the arterioles, haemorrhages, papilloedema

the seriousness of the condition. It is

and exudates, are beyond doubt. Some confu-

caused by the increased pressure within

sion can be avoided if it is realised that the

the orbit, where enlargement of the

effects of raised blood pressure are modified by

extraocular muscle causes crowding of the

other changes in the eye because of natural

orbital apex with subsequent compression

ageing. It is now accepted that the exact cause of

of the optic nerve. The first sign can be

the raised blood pressure does not by itself

swelling of the optic disc, followed by optic

influence the fundus appearance. However, the

atrophy. It is, therefore, vitally important to

appearance of the retinal vessels and associated

monitor the visual acuity and central

changes serve as a good guide to the severity of

visual field in these cases.

the disease and urgency of treatment.

Management

The Effect of Age on the Retinal

Blood Vessels

Reassurance is all that might be required in the

mild forms of the disease. In some cases, treat-

In older patients the retinal arteries are seen to

ment is usually limited to that of the exposure

be narrower and straighter and the veins are

keratitis. Ocular lubrication with artificial tear

also narrower than in younger patients. The

drops, and an antibiotic ointment instilled at

term “retinal arteriosclerosis” is used to des-

night is often sufficient. Sometimes a small

cribe these changes.

lateral tarsorrhaphy on each side can greatly

improve the appearance of a young girl with lid

retraction. Lid retraction can also be improved

The Effects of Raised Blood Pressure

by the use of guanethidine eye drops.

on the Retinal Vessels

If there is visual deterioration (from optic

nerve compression or significant proptosis),

In younger patients, irregular narrowing of the

large doses of systemic steroids are probably the

retinal arterioles is seen, and is thought by many

best line of treatment (e.g., prednisolone 120 mg/

to be because of spasm of the vessel walls. This

day). Initial recovery is usually dramatic and

hypertonicity leads in time to more permanent

rapid but then the side effects of systemic

changes in the vessel walls so that the vessels

steroids ensue. The dose should be reduced

resemble those of an older patient.Nipping of the

as soon as feasible but it might be necessary to

veins at arteriovenous crossings is seen and on

continue with a maintenance dose for many

the distal side of the crossing the vein can be dis-

months. Some ophthalmologists might use other

tended. Occasional flame haemorrhages, cotton-

immunosuppressive agents, such as azathio-

wool spots and exudates might indicate more

prine, or orbital radiotherapy in severe cases of

severe vascular damage but do not necessarily

proptosis and/or optic nerve compression. If

lead to “malignant” hypertension (Figure 21.11).

Systemic Disease and the Eye

173

Other Associated Vascular Changes

Retinal Vascular Occlusion

This is more common in hypertensive patients

compared with normotensives. The most fre-

quent occurrence is the central retinal vein

occlusion (CRVO), although branch retinal vein

occlusions can occur at arteriovenous crossings.

The fundus appearance in CRVO is dramatic

with numerous scattered haemorrhages and

swelling of the optic disc, and the patient expe-

riences sudden blurring of vision in one eye

(Figure

21.12). This can be compared with

occlusion of the central retinal artery, which is

less common and in which the prognosis is uni-

Figure

21.11. Hypertensive retinopathy: haemorrhages,

formly worse. Here, the fundus appears pale and

cotton-wool spots, exudates, vascular calibre changes.

the arteries are narrowed. There is a cherry-red

spot at the macula.

In older patients, the already narrowed

vessels tend to show less dramatic changes.

Hypertonicity of the vessel walls is not seen but

arteriovenous nipping remains an important

sign and haemorrhages might be present in

more severe cases. The cotton-wool spots of

hypertension reflect ischaemic damage to the

nerve fibre layer caused by obstruction of the

retinal precapillary arterioles. Exudates are

caused by abnormal vascular permeability.

“Malignant” Hypertension

Occasionally, patients with a severe hypertensive

problem present directly to the ophthalmologist

because their main symptom is blurring of the

vision, the other more usual symptoms being

less evident. On examination, the visual acuity

might be only slightly reduced unless there is

significant macular oedema and there might be

some enlargement of the blind spot and con-

striction of the visual fields. Inspection of the

fundus reveals marked swelling of the optic disc,

the oedema often extending well away from the

disc with scattered flame-shaped haemorrhages.

If the diastolic blood pressure is above 110-

120 mmHg, there is little doubt about the diag-

nosis, but below this level it is essential to bear

in mind the possibility of raised intracranial

pressure from other causes. When hypertension

is as severe as this, the patient should be treated

as an acute medical emergency and referred

Figure 21.12.

a Central retinal vein occlusion and b macular

without delay to the appropriate physician.

branch retinal vein occlusion.

174

Common Eye Diseases and their Management

conjunctiva, similar to oral mucosa, is pale. The

retinal vessels become pale and the difference

between arteries and veins becomes less appar-

ent. The fundus background also appears pale

but this sign is dependent upon the natural

pigmentation of the fundus and can be mis-

leading. In severe cases, small haemorrhages are

usually seen, mainly around the optic disc. The

haemorrhages tend to be flame-shaped but a

special feature of anaemic retinopathy is the

presence of white areas in the centre of some

of the haemorrhages. The haemorrhages might

be due to associated low platelet counts. In

pernicious anaemia, retinal haemorrhages and

Figure 21.13. Anterior ischaemic optic neuropathy. The sup-

bilateral optic neuropathy that manifests as cen-

erior part of the disc is pale.

trocaecal scotomas are seen. In severe cases, the

optic nerves are atrophic. Anaemia secondary to

blood loss can give rise to ocular hypoper-

Emboli

fusion, which leads to anterior ischaemic optic

Cholesterol emboli can be seen in the retinal

neuropathy. Examination of the conjunctiva is

arteries, sometimes in association with arterial

perhaps of more value or at least is certainly

occlusion. These usually arise from atheroma-

an easier way of assessing the haemoglobin

tous plaques in the carotid artery. Calcified

level and this part of the examination of the eye

emboli can be seen in association with diseased

should, of course, precede ophthalmoscopy.

heart valves and platelet or fibrin emboli can

also be observed.

The Leukaemias

Ischaemic Optic Neuropathy

All ocular tissue can be involved in leukaemia.

Some elderly patients complaining of visual loss

The eye changes can occur at any time during

in one eye are found to have a pale swollen optic

the course of leukaemia, or they can make up

disc and sometimes evidence of branch retinal

the presenting features of the disease. These

artery occlusion, giving an altitudinal defect of

changes are more common in the acute

the visual field. This appearance should suggest

leukaemias than in the chronic types.

the possibility of temporal arteritis and an

Two groups of ophthalmic manifestations

erythrocyte sedimentation rate

(ESR) and a

are recognised in leukaemias. The first group

temporal artery biopsy should be considered as

consists of leukaemic infiltration of ocular

urgent investigations (Figure 21.13).

structures, for example retinal and preretinal

However, there is a group known as “non-

infiltrates or anterior chamber and iris deposits.

arteritic” or idiopathic anterior ischaemic optic

All of these are quite uncommon. The second

neuropathy (AION), which occurs in otherwise

group of manifestations is considered to be

healthy individuals between 45 and 65 years of

secondary to the haematological changes, for

age. About one-third of these patients develop

example thrombocytopenia, increased blood

bilateral disease. In these patients, retinal arte-

viscosity and highly increased leucocyte count.

rial occlusion is absent. There is no known treat-

These changes include subconjunctival haemor-

ment for nonarteritic AION but giant cell

rhages and intraretinal haemorrhages, includ-

arteritis needs to be excluded.

ing white centred ones, cotton-wool spots, “slow

flow retinopathy” (Figure

21.14) and retinal

Anaemia

venous occlusions (especially CRVO).

Less common manifestations include

When the haemoglobin concentration in the

choroidal infiltrations, and retinal and optic

blood is abnormally low, this becomes apparent

disc neovascularisations. Apart from eye

in the conjunctiva and ocular fundus. The

changes, the vision can be impaired by

Systemic Disease and the Eye

175

deformable compared with normal, leading to

occlusion of the small retinal blood vessels

especially in the retinal periphery.

Sickle-cell retinopathy can be divided into two

types: (1) nonproliferative and (2) proliferative.

In nonproliferative sickle retinopathy there is in-

creased venous tortuosity, peripheral choriore-

tinal atrophy, peripheral retinal haemorrhages,

peripheral haemosiderin deposits, which appear

refractile,and peripheral arterial occlusion.These

lesions are usually asymptomatic. When central

retinal arterial or venous occlusion, macular

arteriolar occlusion or choroidal ischaemia

occurs, there is significant visual deficit.

When significant ischaemia is present, retinal

Figure 21.14. The fundus in leukaemia. Note dilated veins

neovascularisation occurs. This is generally in

and haemorrhages.

the retinal periphery. Such peripheral neovas-

cularisation can respond to laser photocoagula-

tion or cryotherapy of the retina. Occasionally

vitrectomy is required.

leukaemic infiltrates elsewhere in the visual

pathway (leading to field defects).

Ocular disease can also occur as compli-

Onchocerciasis

cations of treatment of the leukaemia, for

example opportunistic infections such as

Onchocerciasis, commonly known as river

herpes zoster, graft-versus-host reactions and

blindness, is caused by the filaria Onchocerca

intraocular haemorrhage.

volvulus. The name “river blindness” is derived

from the occurrence of the disease in focal areas

along rivers and streams where the blackfly

Sickle-cell Disease

(Similium) breeds in fast-flowing water. The

blackfly can travel several kilometres and does

This condition is mentioned separately because

not respect international borders.

of the severe and devastating effect it can

The disease is characterised by a few adult

have on the vision. The sickle-cell haemoglo-

worms encased in nodules and the invasion of

binopathies are inherited and result from the

the body by microfilaria produced by the adult

affected person having one or more abnormal

worms. It is endemic in equatorial Africa - West

haemoglobins as recognised by the electro-

and Central - and Central and South America.

phoretic pattern and labelled alphabetically.

It is estimated that there are about half a million

Haemoglobins S and C are the most important

blind people because of onchocerciasis.

ophthalmologically. Thalassaemia (persistence

The adult worm has a lifespan of 15-30 years.

of foetal haemoglobin) can also cause retinopa-

The microfilaria is sucked up by the blackfly

thy. The abnormal haemoglobins occur either in

when it takes its blood meal. Subsequently, divi-

combination with normal haemoglobins result-

sion within the blackfly gives rise to latter stages

ing in AS (sickle-cell trait) or in association with

of the larva, which are re-injected into the skin

each other: SS (sickle-cell anaemia or disease)

of the next victim of the blackfly’s bite. The

or SC (sickle-cell haemoglobin C disease) and S

microfilariae migrate under and through the

thal (thalassaemia). Individuals with cell trait

skin and may mature in about one year. Newly

usually lead a normal life and do not have any

produced microfilariae migrate to the eye

systemic or ocular complications. The red blood

through the skin or blood.

cells in patients with sickle-cell (SS, SC, S thal)

Clinical manifestations of onchocerciasis

disease adopt abnormal shapes under hypoxia

can be divided into extraocular and ocular

and acidosis. These abnormal red cells are less

manifestations.

176

Common Eye Diseases and their Management

Extraocular Features

Acquired Immune Deficiency

Skin involvement is in the form of pruritis - a

Syndrome (AIDS)

maculopapular rash, which can be associated

with hypo- or hyperpigmentation, dermal and

Acquired immune deficiency syndrome (AIDS)

epidermal atrophy or “onchodermatitis”.

refers to the final stages of infection by the

There might be subcutaneous nodules, which

human immunodeficiency virus

(HIV). The

are firm, round masses in the dermis and sub-

earlier stages of the disease are often asympto-

cutaneous tissue, especially close to joints in the

matic (Table 21.4).

head and shoulder.

In western countries, AIDS commonly affects

homosexuals, haemophiliacs, and intravenous

Ocular Features

drug abusers, although there is now a significant

heterosexual and paediatric pool of patients. In

Intraocular microfilariae can be seen in the

Africa, it is generally a heterosexual disease, and

anterior chamber. Dead microfilariae are usually

a significant paediatric population is also

seen in the cornea (especially peripherally).

known. Transmission is through sexual inter-

Other ocular features are punctate keratitis

course, parenteral or transplacental routes.

and sclerosing keratitis; anterior uveitis, usually

Ocular features occur in 75% of patients with

of the nongranulomatous type with loss of

AIDS. The major ocular complications of AIDS

the pigment frill, and posterior synechiae are

occur later in the disease and can be predicted

common. Secondary cataract and glaucoma

by CD4 T-cell levels. At CD4 level >200

¥ 10⁶/L

can develop.

common ocular complications are toxoplas-

Chorioretinitis of the chronic nongranulo-

mosis and herpes zoster ophthalmicus and

matous type can occur, with secondary degen-

retinitis, while at CD4 levels <50

¥ 10⁶/L cyto-

erative changes in the retinal pigment

megalovirus (CMV) retinitis is common.

epithelium (RPE) neuroretina and the chorio-

AIDS microangiopathy (noninfectious) occurs

capillaries. There might be granular atrophy of

in about 50% of patients (in both developing

the RPE, subretinal fibrosis, retinal arteriolar

and western countries). It consists of microa-

attenuation and vasculitis. Optic atrophy and

neurysms, telangiectasia, cotton-wool spots and

neuropathy are not uncommon.

a few retinal haemorrhages. Retinal peripheral

Diagnosis is confirmed by skin snip and the

perivascular sheathing may sometimes occur

Mazzoti test, which depends on a Herxheimer

in the absence of intraocular infections.

reaction to a single dose of diethylcarbamazine.

Other ocular involvement of AIDS in-

Care is required with this test because the reac-

cludes infections with opportunistic and

tion could be severe.

Management

One method is by vector control. An inter-

Table 21.4. Classification of human immunodeficiency virus

national (World Health Organisation) program-

(HIV) infection (Centers for Disease Control, Atlanta, 1992).

me, the onchocerciasis control programme, has

Group I

Acute infection: asymptomatic with

been successful in reducing the endemicity of

seroconversion

the disease in the Volta river basin.

Group II

Asymptomatic carrier

Chemotherapy of infected patients now uses

Group III

Generalised, persistent

Ivermectin, which in a single dose rids the

lymphadenopathies; usually good

patient of microfilariae for one to two years.

state of general health

This medication needs to be repeated over

Group IV

several years in mass administration projects.

AIDS

Diethylcarbamazine is the older treatment for

Sub-

(A) Constitutional (cachexia, fever, etc.).

groups

(B) Neurological.

the microfilariae but is more toxic and requires

to be taken over a two- to three-week period.

(D) Malignancies.

Adult worms can only be killed by suramin, or

(E) Others, e.g. CD4 count <200

¥ 10⁶/L.

removed surgically.

Systemic Disease and the Eye

177

ficant elevation of CD4 T-cell levels such that the

ocular complications, especially opportunistic

infections, are less commonly encountered.

Ophthalmological Signs of AIDS

Noninfectious retinopathy:

(a) cotton-wool spots

(b) retinal haemorrhages

Figure 21.15. Cytomegalovirus retinitis in acquired immune

Opportunistic infections:

deficiency syndrome (AIDS).

(a)

Involvement of posterior segment:

• CMV retinitis

• acute retinal necrosis

(herpes

nonopportunistic organisms (e.g., CMV, crypto-

simplex, herpes zoster)

coccus and molluscum contagiosum) (Figures

• toxoplasmic chorioretinitis

21.15 and 21.16). Neoplasms of the conjunctiva,

• Pneumocystis carinii choroiditis

lids and orbit, and neurophthalmic complica-

• tuberculous choroiditis

tions are other features.

• endophthalmitis caused by Candida

In western countries, the commonest ophthal-

albicans - usually intravenous drug

mic complication of AIDS is CMV retinitis,

users

while in developing countries (such as Africa),

CMV is not a major problem. Herpes zoster

• cryptococcus chorioretinitis

ophthalmicus and conjunctival carcinoma are

• syphilitic retinitis

common in AIDS patients in Africa and AIDS

(b)

Involvement of anterior segment:

patients die of other complications, for example

• chronic keratitis and keratouveitis

tuberculosis. Therefore, short-term survival

caused by herpes zoster and herpes

from AIDS itself is a problem in developing

simplex

countries, while in western countries quality of

• keratoconjunctivitis caused by CMV,

life for the longer term is the main problem.

microsporum and gonococcus

Treatment with the highly active antiretro-

• corneal ulcer caused by Candida albi-

viral therapy (HAART) regimen leads to signi-

cans, and bacteria

(Pseudomonas

aeruginosa, Staphylococcus aureus,

and Staphylococcus epidermidis)

• syphilitic and toxoplasmic iridocyclitis

• conjunctivitis caused by CMV,herpes

zoster and herpes simplex

• bacterial conjunctivitis.

Neoplasms:

(a) conjunctival, palpebral and orbital

Kaposi’s sarcoma

(b) intraocular lymphoma

• conjunctival squamous carcinoma

• palpebral and orbital lymphoma.

Neuro-ophthalmological signs:

Figure 21.16. Human immunodeficiency virus retinopathy.

(a) Involvement of cranial nerves:

178

Common Eye Diseases and their Management

• internuclear ophthalmoplegia

(d)

Retina:

• third, fourth and sixth cranial

• talc-induced retinopathy

(only

nerve palsies

intravenous drug users)

• retrobulbar neuritis and papillitis

(e)

Eyelids:

(b) Homonymous haemianopia

• herpes zoster ophthalmicus

• palpebral molluscum contagiosum

blindness.

• palpebral cryptococcosis

Other signs:

(f)

Orbit:

(a) Conjunctiva:

• orbital apex granuloma

• nonspecific conjunctivitis

• orbital pseudotumour

• keratoconjunctivitis sicca

• orbital infiltration by Aspergillus,

• nonspecific conjunctiva micro-

Pneumocystis carinii

vascular changes in the inferior

• orbital cellulitis

perilimbal bulbar region (haemor-

(g)

Visual and refraction defects:

rhages, microaneurysms, column

• night blindness because of vitamin

fragmentation, dilatation and irreg-

A and E malabsorption

ular vessel diameter)

• progression of myopia

• bacterial conjunctivitis

• decreased accommodation

(b) Cornea:

(h)

Acute closed-angle

(bilateral) glau-

• nonspecific punctate keratitis

coma caused by choroidal effusion.

• necrotising scleritis.

Neuro-ophthalmology

It is found in most ophthalmic departments that

deceptively pale and some elderly discs appear

it is necessary to retain a close liaison with

atrophic without evidence of disease. Pallor of

neurological and neurosurgical departments,

the disc is caused by loss of nerve tissue and

and neuro-ophthalmology is now in itself a sub-

small blood vessels of the surface of the disc. In

specialty. Retrobulbar neuritis, for example, is a

severe optic atrophic cupping, there is exposure

condition that presents quite commonly to eye

of the underlying sclera. The myopic disc is rel-

casualty departments and usually requires

atively pale, whereas the hypermetropic disc is

further investigation by a neurologist. Less

pinker than normal (Figure 22.1).

common but equally important are the pituitary

tumours, which, it will be seen, can present in a

Margins

subtle way to the ophthalmologist and can

require urgent medical attention. There are

These are better defined in myopic than in

many other, sometimes rare, conditions, which

hypermetropic subjects. In hypermetropes the

find common ground between the disciplines.

edges of the disc can appear raised, sometimes

resembling papilloedema. It is common to see a

The Optic Disc

crescent of pigment on the temporal side of the

disc. Frequently, an area of chorioretinal

Normal Disc

atrophy is present at the disc margin in myopes

and can give rise to difficulty in deciding where

One must be familiar with some of the vari-

the true disc margin is.

ations found in otherwise normal individuals

before being able to diagnose pathological

Vessel Entry

changes. The optic discs mark the entrance of

the optic nerves to the eye and this small circ-

In general, a central retinal artery and vein

ular part of the fundus is nonseeing and cor-

divide into upper and lower branches, which in

responds with blind spots in the visual field.

turn divide into nasal and temporal branches

When examining an optic disc, five important

close to the disc margin. Many variations in the

features are to be noted: the colour, the margins

pattern are seen normally. The veins are darker

or contour, the vessel entry, the central cup and

and wider than the arteries and, unlike the

the presence or absence of haemorrhages.

arteries, can be seen to pulsate spontaneously in

80% of the population if examined carefully. In

Colour

the other 20% of normal individuals, venous

The disc is pink but often slightly paler on the

pulsation at the disc can be induced by gentle

temporal side. That of the neonate might be

pressure on the globe.

179

180

Common Eye Diseases and their Management

Congenital Disc Anomalies

A number of minor congenital abnormalities

are seen on the disc. In an astigmatic eye, the

disc is often oval. The central cup might be filled

in by “drusen” - small hyaline deposits, which

can be found on the surface or buried in the sub-

stance of the disc. This appearance can mimic

papilloedema. Alternatively, the central cup

might be hollowed out further by a congenital

pit in the disc. Myelinated retinal nerve fibres

are recognised by their strikingly white appear-

ance, which obscures any underlying vessels,

and their fluffy margin (see Figure 22.3). The

central cup can be filled in by persistent rem-

nants of the hyaloid artery

(Bergmeister’s

papilla), which runs in the embryo from disc to

lens. Some of these and other congenital abnor-

malities of the disc can be associated with visual

field defects that are not progressive but which

can cause diagnostic confusion.

Pale Disc

Optic Atrophy

Optic atrophy means loss of nerve tissue on the

disc, and the resulting abnormal pallor of

the disc must be accompanied by a defect in the

visual field, but not necessarily by a reduction in

the visual acuity. It must be remembered that

the disc tends to be somewhat pale and the cup

Figure 22.1. Normal optic disc in a myope and b hypermetrope.

of disc tends to be larger in short-sighted eyes

and care must be taken in diagnosing optic

atrophy in such cases. The number of small

vessels, which can be counted on the disc, is

sometimes used as an index of atrophy in

difficult cases.

Central Cup

Classification of the causes of optic atrophy

The centre of the disc is deeper (i.e., further

usually includes the term “consecutive optic

away from the observer) than the peripheral

atrophy”, referring to atrophy following retinal

part. This central cup occupies about one-third

degeneration. The terms primary and second-

(or less) of the total disc diameter in normal

ary atrophy are also used but because these

subjects. The ratio between the vertical diame-

terms are confusing a simple aetiological

ter of the cup and the total disc diameter is

classification will be used here. It should be

known as the cup-to-disc ratio. Thus, the

borne in mind that it is not usually possible to

normal cup-to-disc ratio is <0.3.

determine the cause of optic atrophy by the

appearance of the optic disc. Even the cupped,

pale disc of chronic glaucoma can be mimicked

Haemorrhages

by optic atrophy because of chiasmal compres-

Haemorrhages are never seen on or adjacent

sion. When optic atrophy follows swelling of the

to normal discs. If present, they warrant

optic disc, there is more gliosis than when it is

further investigation.

“primary”, that is, caused by disease in the nerve

Neuro-ophthalmology

181

itself. Gliosis makes the appearance of the disc

•

Toxic. A number of poisons can specifically

more grey or yellowish-grey than white and the

damage the optic nerve; methyl alcohol is

cribriform markings often seen in optic atrophy

a classical example. Tobacco amblyopia is a

might not be evident.

type of progressive atrophy resulting from

The following are the important causes of

excessive smoking of coarse tobacco,

optic atrophy:

usually in a pipe and often in association

with a high ethyl alcohol intake. Reversal

•

Glaucoma.

can be achieved by abstention in the early

•

Vascular. Following obstruction of the

phases of the disease. Other toxic agents

central retinal artery or vein, giant cell

include ethambutol, isoniazid, digitalis

arteritis

and nonarteritic anterior

and lead.

ischaemic optic neuropathy.

•

Trauma. The optic nerve can be damaged

•

Following disease in the optic nerve, for

by indirect injury if bleeding occurs into

example optic neuritis, or compression of

the dural sheath. This can result from a

the nerve by an aneurysm or tumour

fracture in the region of the optic foramen

(Figure 22.2).

or rarely, from contusion of the eye itself.

•

Following papilloedema. The disc can

After the nerve has been damaged, a period

become atrophic as a direct result of the

of a few weeks elapses before the nerve

chronic swelling, irrespective of its cause.

head becomes atrophic, so that initially the

•

Inherited. Retinitis pigmentosa is an

eye could be blind but the fundus normal.

inherited retinal degeneration in which

The pupil reaction to direct light is

there is a progressive night blindness, con-

impaired from the time of the injury. Such

striction of the visual field and scattered

an injury can result in complete and per-

pigmentation in the fundus. As the condi-

manent blindness in the affected eye but a

tion advances toward blindness, the discs

degree of recovery is achieved in a small

become atrophic.Optic atrophy might also

proportion of cases, if decompression of

appear in certain families without any

the nerve sheath is undertaken early.

other apparent pathology, for example

Leber’s hereditary optic neuropathy and

Swelling of the Optic Disc

autosomal dominant optic atrophy. It

is also seen in the rare but distressing

This is a serious sign because it could be caused

cerebroretinal degeneration, which pres-

by raised intracranial pressure and an intracra-

ents with progressive blindness, epilepsy

nial space-occupying lesion. There are, however,

and dementia.

a number of other more common causes.

Apparent Swelling

The margins of the optic disc might be ill-

defined and even appear swollen in hyper-

metropic eyes. Other congenital abnormalities

of the disc, such as drusen or myelination of the

nerve fibres, may also be mistaken for true

swelling (Figure 22.3).

Vascular

The disc can be swollen in congestive cardiac

failure or in patients with severe chronic emphy-

sema. Marked swelling of the disc with numer-

ous haemorrhages is seen in occlusion of the

central retinal vein and this compares with the

pale and less haemorrhagic swelling that is seen

Figure 22.2. Optic atrophy caused by pituitary compression of

in anterior ischaemic optic neuropathy. In the

the optic nerve.

latter instance, swelling of the disc occurs in

182

Common Eye Diseases and their Management

dema” refers to the noninflammatory swelling of

the disc, which results from raised intracranial

pressure. The most common causes of raised

intracranial pressure are cerebral tumours,

hydrocephalus idiopathic (benign) intracranial

hypertension, subdural haematoma, malignant

hypertension and cerebral abscess.

Diagnosis of papilloedema entails careful

examination of the optic disc, which must be

backed up with visual field examination and

colour fundus photography. The latter is esp-

ecially helpful when repeated,to show any change

in the disc appearance. Fluorescein angiography

can also be of great diagnostic help in difficult

cases when abnormal disc leakage occurs.

Figure 22.3. Myelinated nerve fibres.

Optic Neuritis

This most commonly occurs in association with

a plaque of demyelination in the optic nerve in

patients with multiple sclerosis. The central

association with arterial disease and one must

vision is usually severely affected, in contrast

take pains to exclude temporal arteritis in

with papilloedema, but optic neuritis occurs in

the elderly.

many instances without any visible swelling of

the disc (retrobulbar neuritis).

Postoperative

Other Causes

Swelling of the disc is not uncommon in the

immediate postoperative period after intra-

Chronic intraocular inflammation,such as anter-

ocular surgery. It is caused by ocular hypotony.

ior, intermediate or posterior uveitis, can be

It can persist for longer periods if the intraocu-

complicated by disc swelling. Severe diabetic

lar pressure remains low. It is not usually

eye disease can sometimes be marked by disc

regarded to be of serious significance, because

swelling (diabetic papillopathy). In severe cases

the swelling regresses following normalisation

of thyroid orbitopathy, the orbital congestion

of the intraocular pressure.

True Papilloedema

Papilloedema is swelling of the optic discs

because of increased intracranial pressure.

Every doctor must be aware of the triad of

headache, papilloedema and vomiting as an

important feature of raised intracranial pres-

sure. The optic disc might be markedly swollen

and haemorrhages are present around it, but not

usually in the peripheral fundus (Figure 22.4).

In chronic papilloedema, the disc is paler and

haemorrhages might be few or absent. Although

these patients might complain of transient blur-

ring of the vision, the visual acuity is usually

normal and testing the visual fields shows only

some enlargement of the blind spots. It is

important to realise that the word “papilloe-

Figure 22.4. Papilloedema.

Neuro-ophthalmology

183

can cause disc swelling (dysthyroid optic neu-

can be lost completely. On examination, a rela-

ropathy). In both instances, the doctor should be

tive afferent pupil defect on the affected side

warned that serious consequences might ensue

might be the only objective evidence of disease.

unless prompt treatment is applied. Infiltration

It is essential to test the pupil before dilating it

of the disc by leukaemia, lymphoma or chronic

with eye drops. The fundus is often normal ini-

granulomata (as in sarcoidosis) can also cause

tially (retrobulbar neuritis), although there can

disc swelling.

be slight swelling of the optic disc (optic neuri-

tis). After two or three weeks the optic disc

starts to become pale. The visual prognosis is

generally good. Most patients make a complete

Multiple Sclerosis

or nearly complete recovery after 6-12 weeks.

The attack is unilateral in 90% of cases, although

This common and important neurological

there is a risk that the other eye can be affected

disease can often present initially as an eye

at a later date and recurrent attacks in one or

problem and its proper management requires

both eyes can cause permanent damage to the

careful co-ordination at the primary care level.

vision. Fortunately, it is extremely rare for a

It is important to realise that multiple sclerosis

patient to be made blind by multiple sclerosis.

should not be diagnosed after one single attack

The diagnosis at the time of the acute attack

of optic or retrobulbar neuritis because this

relies on the history and noting the pupil reac-

could cause unnecessary alarm about some-

tion. It is often advisable to make the diagnosis

thing that might never happen. Studies have

in retrospect. The patient might give a history of

shown that between 45% and 80% of patients

visual loss in one eye, which has recovered, and

with optic neuritis will develop multiple sclero-

at a later date, presents with other nonocular

sis after

15 years of follow-up. Furthermore,

signs and symptoms of demyelinating disease.

optic neuritis has causes other than multiple

If it can be confirmed that the patient has had a

sclerosis. The diagnosis of multiple sclerosis

previous attack of optic neuritis, this can help in

should be made by a neurologist and is based on

the confirmation of the diagnosis of dissemi-

finding additional evidence of the disease else-

nated sclerosis. Under these circumstances, the

where in the body.

pallor of the disc can be helpful, but careful

The cause of multiple sclerosis is not known,

assessment of the colour vision, visual acuity

but the disease is characterised by the appear-

and measurement of the visually evoked poten-

ance of multiple inflammatory foci in relation to

tial can provide conclusive evidence. At the time

the myelin sheaths of nerves throughout the

of the acute attack, testing the visual field might

central nervous system. The demyelination

reveal a central scotoma. The size of this defect

plaques are detectable on magnetic resonance

diminishes as healing occurs, often leaving a

imaging scans of the brain. The optic nerve

small residual defect between blind spot and

between globe and chiasm is commonly involved

central area.

at an early stage and there might be a delay of

Corticosteroids administered systemically

several years before other features of the disease

can speed up recovery of vision. However,

appear.Young or middle-aged people are mainly

the final visual outcome is unchanged by

affected and the prognosis is worse when the

such treatment.

disease is acquired at an early age.

Nystagmus

Ocular Findings

This usually appears at a later stage than optic

Optic or Retrobulbar Neuritis

neuritis and might only be evident in lateral

gaze. It is often horizontal.

This is an important cause of unilateral sudden

loss of vision in a white eye in a young person.

The patient complains of pain behind the eye on

Internuclear Ophthalmoplegia

attempting to move it and there is often a grey

or coloured patch in the centre of the field of

Whereas double vision is a common symptom

view. In severe cases, the sight of the affected eye

in multiple sclerosis, it is unusual to see an

184

Common Eye Diseases and their Management

Visual Fields

Retina

Optic nerve

Optic chiasma

Optic tract

Lateral geniculate

body

Optic radiation

Occipital cortex

Figure 22.5. The visual pathway.

obvious defect of the ocular movements.

by nerves to the right occipital cortex and the

Sometimes it can be seen that one eye fails

splitting of nerve fibres from each half occurs

to turn inwards when the patient is asked to

at the chiasm. For this reason, lesions in the

look to the opposite side, and yet when the

optic nerve anterior to the chiasm tend to

patient is made to converge the eyes on a near

cause unilateral defects, whereas those pos-

object, the medial rectus moves normally.

terior to the chiasm produce hemianopic or

This failure of the muscle action with certain

quadrantianopic defects (Figure 22.5). Cortical

co-ordinated eye movements only (i.e., limita-

lesions tend to be more congruous. That is to

tion of adduction), while the opposite abducting

say, the blind areas on each side tend to be

eye shows nystagmus, is termed “internuclear

similar in shape and size. Cortical lesions also

ophthalmoplegia”. It is characteristic of multi-

show better preservation of central vision

ple sclerosis when seen in young people (when

(“macular sparing”). A special type of field

the internuclear ophthalmoplegia is usually

defect is seen with expanding pituitary

bilateral and is caused by a demyelinating lesion

tumours, the resulting pressure on the centre of

in the pons) but usually has a vascular cause in

the chiasm producing a bitemporal defect.

the elderly (when it is usually unilateral).

Localised defects in the retina produce equiva-

lent localised defects in the visual field on the

affected side. Defects because of ocular disease

Other Features

are relatively common as, for example, those

Other types of ocular muscle dysfunction, for

seen in the elderly with glaucoma. Care must be

example a lateral rectus palsy or ptosis, are rare.

taken to interpret field defects with this pos-

Careful inspection of the fundi in some cases

sibility in mind. Notice from the diagram in

reveals inflammatory changes around the

Figure 22.5 that the right half of the visual

retinal vessels, especially in the periphery

field is represented in the left half of each

(peripheral retinal vasculitis).

retina and thus, the left half of the brain.

This complies with the general rule that

events occurring on the right side of the body

Defects in the Visual Fields

are represented on the left side of the brain. It is

surprising how patients might be unaware of a

The pattern of a visual field defect gives useful

severe visual field defect, especially in hemi-

localising information for lesions in the visual

anopia, providing that the macula is spared

pathway. The right half of each retina is linked

(Figure 22.6).

Neuro-ophthalmology

185

Miosis refers to a small pupil, mydriasis to a

large pupil

(big word, big pupil). The pupil

grows smaller with age, as does reactivity. In

young children the pupils are relatively large

and sometimes anxious parents bring up their

children because they are concerned about this.

During sleep, the pupils become small. When

examining the eye with the ophthalmoscope, it

is evident that the pupil constricts more vigor-

ously when the macula is examined than when

the more peripheral fundus is stimulated with

the ophthalmoscope light. When an eye is totally

blind, usually there is no light pupil reaction, but

as a general rule, the pupils remain of equal size.

It should be apparent from Figure 22.7 that the

patient with cortical blindness (lesion within

the occipital cortex) might have a normal pupil

My car keeps knocking my gate post.

reaction. We must also remember that a pupil

(Hemianopes should never drive)

might not react to light because it is mechani-

Figure 22.6. The effects of hemianopia.

cally bound down to the lens by adhesions (pos-

terior synechiae). When both maculae are

damaged by senile macular degeneration, the

Abnormalities of the Pupil

The pupil constricts and dilates largely under

the action of the sphincter muscle, which lines

the pupil margin. It is supplied by parasym-

pathetic fibres travelling within the third cranial

Optic

nerve. The afferent stimulus is conveyed along

nerve

Ciliary ganglion

the optic nerves and decussates at the optic

chiasm and continues as the optic tract. The

specific pupillomotor nerve fibres leave the

optic tract without synapsing in the lateral

geniculate nucleus and pass to the pretectal

nucleus of the midbrain, where they synapse

with interneurons. The interneurons project to

Optic tract

both Edinger-Westphal nuclei (part of the third

cranial nerve nucleus). The pupillomotor fibres

III

then travel within the third cranial nerve to the

nerva

pupil constrictor muscles of the ipsilateral eye

via the ciliary ganglion (Figure 22.7).

Red

The dilator muscle is arranged radially within

Lateral geniculate

nucleus

the iris and responds to the sympathetic nerves

nucleus

conveyed in the sympathetic plexus overlying

the internal carotid artery. These fibres, in turn,

Edinger

Pretecto-

Westphal

oculomotor

arise from the superior cervical ganglion. The

nucleus

tract

sympathetic supply to the dilator muscle, there-

fore, runs a long course from the hypothalamus

to the midbrain and spinal cord, and then up

Pretectal nucleus

again from the root of the neck with the inter-

nal carotid artery.

Figure 22.7. The pupillary pathway.

186

Common Eye Diseases and their Management

pupils can be slightly wider than normal

glaucoma and the constricted pupils of the mor-

and might show sluggish reactions. A relative

phine addict are well known if not so commonly

afferent pupil defect (also known as a Marcus

seen. When a constricted pupil on one side is

Gunn pupil) implies optic nerve or severe

observed it is important to note the position of

retinal disease.

the eyelids. A slight degree of associated ptosis

indicates the possibility of Horner’s syndrome.

The total syndrome comprises miosis, narrow-

The Abnormally Dilated Pupil

ing of the palpebral fissure because of paralysis

of the smooth muscle in the eyelids (Müller’s

The most common reason for unilateral mydri-

muscle), loss of sweating over the affected side

asis is drugs in the form of locally administered

of the forehead, a slight reduction of the intra-

eye drops, either prescribed by an ophthalmic

ocular pressure and enophthalmus

(sunken

department or obtained from a friend’s medi-

globe). Horner’s syndrome can be caused by a

cine cabinet. The next most common cause is

wide diversity of lesions anywhere along the

probably the Adie’s pupil, a condition that is

sympathetic pathway. While a Pancoast’s apical

more common in young female patients. The

lung tumour is classically associated with

affected pupil is usually dilated and contracts

Horner’s syndrome, it is quite often noted in the

slowly in response to direct and indirect stimu-

elderly as an isolated finding and investigation

lation. In bright light, the pupil might constrict

fails to reveal a cause. The Argyll Robertson

slowly on the affected side and take some time to

(AR) pupil is a rare but famous example of the

dilate in the dark. The vision might also be

miosed pupil, which responds to accom-

blurred, particularly at near fixation because of

modation but not to direct light. This type of

the effect of the disease process on the ciliary

pupil reaction was originally described as being

muscle (necessary for accommodation). The

closely associated with syphilis of the central

pupillary constriction to near fixation is tonic

nervous system. Visual acuity is normal in

and prolonged and worm-like. When this tonic

such patients.

pupil reaction is combined with absent tendon

jerks in the limbs, it is known as Holmes-

Adie syndrome. When the vision is blurred

Double Vision

and the pupil widely dilated, the symptoms

can be partially relieved by the use of a weak

Double vision (diplopia) can be monocular or

miotic.After a delay of months or years,the other

binocular. Monocular diplopia, that is, diplopia

eye may become affected. The overall disability

that is still present when one eye is closed, is

is minimal and the condition has not so far been

quite common and is usually due to a cataract

related to any other systemic disease. It is

or corneal disease. Some patients say that they

thought to have an underlying viral aetiology.

can see double when they mean that the vision

Acute narrow-angle glaucoma can occasion-

is blurred. A clear distinction must, therefore, be

ally present in this manner and confusion can

made. Binocular double vision of recent onset

arise if the eye is not red; however, closer exami-

should always be treated as a serious symptom.

nation of the eye should make the diagnosis

It is usually disabling, preventing the patient

obvious. Because the nerve fibres, which cause

from working or even walking about. Some

constriction of the pupil, are conveyed in the

patients discover that the symptoms are relieved

oculomotor nerve,oculomotor palsy if complete,

by placing a patch over one eye. Slight degrees

is associated with mydriasis. For this reason,

of double vision can be compensated by a head

dilatation of the pupil can be a serious sign of

tilt or turn and the nature of the adopted head

raised intracranial pressure after head injury.

posture can help to identify the cause of the

One pupil might be wider than the other as a con-

double vision. In the same way, if the history

genital abnormality (congenital anisocoria).

is elucidated carefully, noting, for example,

whether the diplopia is worse for near or dis-

tance vision or whether there is horizontal or

The Abnormally Constricted Pupil

vertical displacement of the second image, then

Again, drugs are a common cause. Miotic drops

a possible cause can be suspected even before

are still encountered in the treatment of

examining the patient.

Neuro-ophthalmology

187

Assessment of Eye Movements

the eye is abducted and that of the obliques is

seen when the eye is adducted.

in Diplopia

Examination of a patient with double vision

entails first of all testing the gross eye move-

The complaint of double vision suggests that the

ments in the cardinal positions of gaze and then

separate eyes are not both fixed on the point of

noting the degree of separation of the images in

regard. The eye that is “off line” sees the object

these various positions. The Hess chart is one of

of regard but it appears displaced. This failure

several ingenious methods of recording the

of the eyes to work together is because of mal-

abnormal eye movements. The principle is to

function of one or a group of eye muscles or the

place a green filter before one eye and a red filter

neurological mechanisms that control them.

before the other and to ask the patient to look

From the clinical point of view, it is conven-

at a screen on which are placed a number of

ient to divide the eye muscles into horizontal

small illuminated white dots. The patient is then

and vertical groups. The horizontal muscles, the

asked to localise the dots with a pointer. The

medial and lateral recti, are easy to understand

amount of false localisation can then be meas-

because their actions are in one plane and they

ured in all positions of gaze. This technique is

simply adduct (turn in) or abduct (turn out) the

invaluable when assessing the recovery of an

globe. The vertical recti are best considered as

ocular muscle palsy.

having primary and secondary actions. It is

Young children adapt to double vision rapidly

important to realise that the action of the ver-

by suppressing the image from one eye, and

tical recti changes with the position of the

under the age of eight years the suppression can

globe. For example, when the eye is abducted the

lead to permanent amblyopia if the situation is

superior rectus elevates the globe, but when

not relieved. In adults, the double vision may

the eye is adducted the superior rectus rotates

persist and be disabling for months or even

the eye inwards round an anterior-posterior

years if not treated by incorporating prisms into

axis (intorts). In a similar manner, the inferior

the spectacles or by muscle surgery.

oblique elevates the adducted eye and extorts

the abducted eye (Figure 22.8). In order to test

the action of the superior oblique muscle, one

Causes of Diplopia

must first ask the patient to adduct the eye and

test for depression in adduction. That is to say,

Ocular Muscle Imbalance

a superior oblique palsy prevents the eye from

It will be recalled from the chapter on squint

looking down when it is turned in. The main

that some patients have a latent squint, which is

line of action of the vertical recti is seen when

controlled much of the time but sometimes

becomes overt. A typical example is the hyper-

metrope with esophoria who begins to com-

plain of double vision when working for an

examination. This problem can be solved simply

by prescribing suitable spectacles. Sometimes

anxious patients who have had a squint since

childhood begin to notice their double vision

Superior rectus

again, having suppressed one image for many

Superior

years. The symptoms are usually relieved with

oblique

the cause of the anxiety.

Lateral rectus

Inferior rectus

Medial

Optic nerva

Sixth Cranial Nerve Palsy

rectus

The affected eye is converged because of a weak-

Superior rectus

ness of the lateral rectus muscle. It occurs most

commonly as an isolated microvascular episode

in hypertensive elderly patients and heals spon-

taneously in three to six months. Elderly dia-

Figure 22.8. The extraocular muscles.

betics are also more prone to sixth cranial nerve

188

Common Eye Diseases and their Management

palsies. In young patients, the possibility of mul-

of the inferior recti in particular becomes

tiple sclerosis or even raised intracranial pres-

impaired and diplopia on upward gaze is a

sure must be borne in mind.

common sign. When the inflammation has

settled, the infiltrating cells are replaced by

fibrous tissue, further restricting muscle action.

Fourth Cranial Nerve Palsy

The eye fails to look down when it is turned in

Myasthenia Gravis

and might be turned slightly up when the other

eye is looking straight ahead. Trauma (a blow

This disease presents sometimes with diplopia

over the head) is an important cause in younger

with or preceded by ptosis,which becomes worse

patients but a full investigation for an intra-

as the day goes by. Any one extraocular muscle

cranial space-occupying lesion is usually needed.

or group of muscles can be affected. The symp-

toms and signs show a transient improvement

seconds after the intravenous injection of edro-

Third Cranial Nerve Palsy

phonium chloride (Tensilon). Diagnosis can be

The eye is turned out and slightly down, the

confirmed by high serum titres of acetylcho-

pupil is dilated and ptosis is usually severe

line receptor antibodies. Approximately 10% of

enough to close the eye. Trauma is an important

cases are associated with a thymoma, which can

cause in young people but a posterior com-

become malignant. A chest X-ray is, therefore,

municating aneurysm should also be consid-

mandatory in any patient suspected of having

ered, particularly if it is associated with pain.

myasthenia gravis. Treatment is with an anti-

Other causes include demyelination, diabetes,

cholinesterase such as pyridostigmine.

microvascular occlusion and herpes zoster

infection. Recovery of nerve function particu-

Blow-out Fracture of the Orbit

larly after compressive lesions can lead to a phe-

nomenon known as aberrant regeneration. This

A special cause of double vision following injury

can manifest as atypical pupil or lid responses

is the trapping of extraocular muscles,usually the

on attempted eye movement.

inferior rectus, in the line of fracture. The patient

experiences double vision on looking upwards

and the limitation of movement is evident.

Thyrotoxicosis

There might be a relative enophthalmos. Surgical

Patients with this condition develop double

intervention to repair the orbital wall defect

vision because the extraocular muscles become

might be required if the patient suffers from

infiltrated with inflammatory cells. The action

prolonged diplopia or marked enophthalmus.

Genetics and the Eye

Many eye diseases are inherited or have familial

be designed specifically, either to suppress its

clustering. It is, therefore, always advisable to

production or to replace the lost function.

enquire about the family history when inter-

Examples of eye disease that have been

viewing a patient with an ophthalmological

mapped out to different chromosomes are

complaint. Some types of inherited eye disease

shown in Table 23.1.

lead to blindness and relatives of patients with

Several methods are used in molecular

such conditions often seek advice concerning

biology to link disease to particular gene loci.

their risk of developing the disease. Patients

Work usually starts by finding and classifying

might also consult with a view to prenatal

the disease in question in a large family or series

testing, particularly if the disease leads to

of families. Next, the disease chromosome is

blindness at a young age.

sought (unless the inheritance pattern is X-

Recent advances in molecular biology have

linked, then this step can be omitted) and then

led to a dramatic increase in our understanding

the position of the gene in question is gradually

of eye diseases. The discovery and the unravell-

narrowed down (by the use of linkage analysis

ing of the role of numerous ocular disease genes

followed by chromosome walking). This usually

has also helped in our understanding of normal

produces a region of the chromosome on which

eye development and functioning. Because of

a number of candidate genes are found.

the advances made in ophthalmic molecular

Sequencing of these genes and comparison with

genetics, we are now able to refer to an inher-

normal individuals or animal models usually

ited ocular condition not only by the mode of

allows the disease gene to be identified (this can

inheritance, but also to denote the abnormal

be a very time-consuming operation). Once

chromosome, the abnormal gene’s position on

the sequence of the gene is known, this can be

the chromosome and its nucleotide sequence.

compared on computer databases with similar

To date, over 150 different gene defects have

known genes and the putative structure and

been described for retinal conditions alone

function of the disease gene and its product

(www.sph.uth.tmc.edu/retnet/home.htm). For

can be determined. The potential of the latter

many disorders, we also now know the role the

has been greatly improved by the project to

abnormal gene plays in the pathogenesis of

sequence the entire human genome.

the disease, either because it leads to the pro-

Eye screening in selected patients at risk of

duction of an abnormally functioning protein

inherited disease might detect important life-

or because the gene defect leads to the abnor-

threatening conditions, for example familial

mal regulation of nearby or distant genes. Once

adenomatous polyposis, retinoblastoma,

the abnormal gene product (protein) associated

Marfan’s syndrome, neurofibromatosis and von

with a disease can be identified, then drugs can

Hippel Lindau disease.

189

190

Common Eye Diseases and their Management

Table 23.1. Chromosome mapping for common eye diseases

Chromosome

Eye disease

Leber’s congenital amaurosis, Stargardt’s disease, open-angle glaucoma (type 1A), congenital cataract,

retinitis pigmentosa

Congenital cataract, iris coloboma aniridia type 1, AR retinitis pigmentosa, congenital glaucoma

Usher’s syndrome, AD retinitis pigmentosa

Treacher Collins mandibulofacial dysostosis

Goldenhar’s syndrome

Aniridia type 2 (sporadic aniridia/Wilms tumour), Best’s disease

Stickler’s syndrome, congenital cataract

13q

Retinoblastoma

Neurofibromatosis type 1 (NF1; Von Recklinghausen’s disease)

22q12

Neurofibromatosis type 2 (NF2)

X Chromosome

Ocular albinism

Juvenile retinoschisis

Norrie’s disease

Choroideremia

Retinitis pigmentosa

(Xq 28)

Colour blindness - blue cone, red cone, green cone

gous). If different, one can exert an overriding

Basic Genetic Mechanisms

influence and is said to be dominant. The gene

that is overridden is said to be recessive.

In order to be able to give advice about the

Genetic disorders can be divided into three

appearance of inherited disease in future gen-

broad groups:

erations, it is essential to have a basic knowledge

of the mechanism of genetic transmission.

• abnormalities of chromosomes - numerical

The nucleus of each cell in the body contains

or structural

46 chromosomes arranged as 23 pairs. The

• abnormalities of individual genes, which

twenty-third pair comprises the sex chromo-

are transmitted to offspring

somes (the remainder being known as auto-

• abnormalities involving the interplay of

somes). These sex chromosomes are responsible

multiple genes and the environment.

for the transmission of sex characters but also

carry a number of other genes unrelated to sex.

Pathological genes can carry abnormalities,

In a woman, the sex chromosomes are the same

which are transmitted to the offspring in the

length but in a man, one is shorter than the

same way as (other) normal characteristics.

other. The shorter one is known as the “Y”

In a given individual, the abnormal gene can

chromosome and the longer one, which is the

be recessive and masked by the other one of

same as the female sex chromosome, is the “X”

the pair. The individual would thus not appear

chromosome. When the sperm or ova are

to have the disease but could transmit it.

formed in the body, the pairs of chromosomes

There are also some other terms that are

separate and the nuclei of the gametes (i.e.,

important when describing genetic abnorm-

sperm or ova) contain only 23 chromosomes.

alities: penetrance refers to the proportion of

When fertilisation occurs, the 23 chromosomes

individuals who carry the gene and who express

from each gamete reunite as pairs. Genetic

the disease, while expressivity refers to the clin-

material is thus equally provided from each

ical spectrum of severity of a particular genetic

parent. Genes are discoid elements arranged

condition. The four important patterns of

along the length of a chromosome and each one

inheritance are:

is known to bear special influence on the devel-

• autosomal recessive

opment of one or more individual characteris-

• autosomal dominant

tics. Genes are arranged in pairs on adjacent

chromosomes. The two genes of the pair can be

• sex-linked recessive

similar

(homozygous) or different (heterozy-

• mitochondrial inheritance.

Genetics and the Eye

191

PARENTS

GAMETES

CHILDREN

Normal

Normal but carriers

Affected

25%

50%

25%

75% apparently normal

Figure 23.1. Recessive inheritance.

be carriers and 50% would be affected. When a

Autosomal Recessive

carrier marries a normal individual, 50% of the

Inheritance

offspring are carriers. These expected findings

could be calculated quite easily using the type

If an abnormal recessive gene is paired with

of diagram shown in Figure 23.1. Common dis-

another abnormal one on the opposite chromo-

eases inherited in this manner include sickle-

some, it will have an effect, but if the opposite

cell disease and cystic fibrosis.

gene is normal, the abnormality will not become

manifest. Recessive disease in clinical practice

usually results from the mating of heterozygous

Autosomal Dominant

carriers. If the abnormal gene is represented by

“a”, the disease will appear in the individual

Inheritance

with genetic configuration “aa” (homozygote)

and not with the configuration “aA” (heterozy-

When a gene bearing a defect or disease gives

gote). When two heterozygotes mate, the likely

rise to the disease even though the other one of

offspring can be considered as in the diagram

the pair is normal, it is said to be dominant. An

(Figure 23.1). If a patient has recessively inher-

affected heterozygote can, therefore, have 50%

ited disease, his or her parents are likely to be

of affected children when married to a normal

normal but there might be brothers or sisters

spouse. Of course, if both spouses carry the

with the disease. It is important to enquire

abnormal dominant gene, all the offspring will

whether the parents are blood relatives because

be affected. Dominant inheritance can only be

this greatly increases the likelihood of trans-

shown with certainty if three successive genera-

mission. If an individual with recessive disease

tions show the disease and if about 5% of indiv-

marries someone with the same recessive

iduals are affected. Also, one sex should not

disease, all the offspring will be affected. If one

be affected more than the other (Figure 23.2).

spouse is a carrier and the other has the disease,

Examples of this type of inheritance are heredi-

there is a risk that 50% of the offspring would

tary retinoblastoma and Marfan’s disease.

192

Common Eye Diseases and their Management

PARENTS

GAMETES

CHILDREN

Unaffected

Affected

50%

Figure 23.2. Dominant inheritance.

X chromosome and the pattern of inheritance

Sex-linked Recessive

is termed X-linked recessive. Examples of this

Inheritance

type of inheritance are seen in ocular albinism

and colour blindness. Retinitis pigmentosa

It has been mentioned already that males have

can also show this pattern in some families.

the “XY” configuration of sex chromosomes,

When inheritance is X-linked, only males are

whereas females have “XX”. Because of the

affected and there is no father-to-son transmis-

unpaired nature of much of the male sex

sion of the disease. Instead, it is conveyed

chromosomes, some recessive genes can have an

through a carrier female to the next generation

effect in males when they do not do so in the

(Figure 23.3).

female. Certain important eye conditions are

This description of the three important

carried in this way in pathological genes on the modes of inheritance should make it apparent

PARENTS

GAMETES

CHILDREN

x X

x Y

Normal girl

Normal boy

Carrier girl

Affected boy

Figure 23.3. X-linked inheritance.

Genetics and the Eye

193

that it is possible to predict the likely disease

moment of fertilisation. These might be caused

incidence in offspring. It should also be realised

by changes in numbers or structure of chromo-

that such predictions can only be based on

somes. Numerical chromosomal changes

careful and extensive investigation of the family.

include the absence of a chromosome (mono-

Although some eye diseases are known to follow

somy), as in Turner’s syndrome, or an additional

a fixed pattern of inheritance, others, notably

chromosome (trisomy), as in Down’s syndrome.

retinitis pigmentosa, can be inherited in differ-

Cytogenetic studies have shown that patients

ent ways in different families. In most large

with Down’s syndrome have an additional

centres, there are now genetic clinics in which

chromosome, which is indistinguishable from

time is devoted specifically to the investigation

chromosome 21. Down’s syndrome is more

of families and also to the detection of carriers.

common in children born to older women and

the eye changes include narrow palpebral

fissures with a characteristic slant, cataract, high

myopia and rather intriguing grey spots on the

Mitochondrial Inheritance

iris known as Brushfield’s spots. Brushfield’s

spots are sometimes seen in otherwise normal

Mitochondria are the only organelles of the cell

individuals. Turner’s syndrome (one missing X

besides the nucleus that contain their own DNA.

chromosome) and Klinefelter’s syndrome (an

They also have their own machinery for syn-

extra X chromosome) are further examples of

thesising RNA and proteins. Instead of in-

disease in which there are known to be abnor-

dividual chromosomes, mitochondria contain

malities of the chromosome, which are visible

circular DNA similar to bacteria (from which

under the microscope. People with these last

they are thought to be derived). Mitochondrial

two diseases are of interest to the ophthalmol-

DNA contains 37 genes, predominately encoding

ogist on account of the abnormal but predic-

the enzymes necessary for the respiratory chain.

table manner in which they inherit colour

All mitochondria in the zygote are derived from

blindness.

the ovum; therefore, a mother carrying a mito-

Structural abnormalities occur when recom-

chondrial DNA mutation will pass it on to all of

bination or reconstitution in an altered form

her children (maternal inheritance) but only her

follows chromosomal breaks. Such changes can

daughters will pass it on to their children. Mito-

be in the form of deletions, duplication inver-

chondrial DNA mutations are usually manifest

sions, translocations or isochromosomes.

clinically in tissues with a high metabolic

demand, for example brain, nerve, retina,

muscle and renal tubule. Examples of ophthal-

mic diseases caused by mitochondrial DNA

Multifactorial Diseases

mutations include Leber’s hereditary optic neu-

ropathy, chronic progressive external ophthal-

These are disorders that arise from an interplay

moplegia, maternally inherited diabetes and

of genetic and environmental influences. The

deafness, and Kearns-Sayre syndrome.

genetic contribution is made up of at least two

abnormal genes acting in concert to express a

“dosage-related” type effect, which is signifi-

Chromosomal Abnormalities

cantly influenced by several environmental

factors. This leads to variable phenotypic

Microscopic studies of the chromosomes them-

expression. Examples include diabetes mellitus,

selves have revealed that abnormal numbers of

some malignancies and perhaps age-related

chromosomes can be produced by a fault at the

macular degeneration.

Drugs and the Eye

It is possible to achieve a high concentration of

use in treating diseases of the vitreous and

many drugs in the eye by applying them as eye

retina. One way of delivering a drug to the

drops. In this way, a high local concentration can

posterior segment is to give it systemically.

be reached with minimal risk of systemic side

An example of this is the use of systemic pred-

effects. However, the systemic side effects of

nisolone for posterior uveitis. This treatment

drops cannot be discounted, particularly in sus-

method has the drawback of systemic side

ceptible individuals. For example, timolol drops

effects. This can be reduced by delivering the

can precipitate asthma and slow the pulse rate

drug to the posterior segment by local injection

in elderly patients, and pilocarpine drops can

either directly into the vitreous, along the

cause sweating and nausea. The action of local

orbital floor, within the sub-Tenon’s space or in

medications can be prolonged by incorporating

the subconjunctival space.

them in an ointment, but for most purposes

drops are supplied in 5 ml or 10 ml containers.

After the container has been opened, it should

Treatment of Infection

not be kept for longer than one month. In order

to avoid undue stinging, drops can be buffered

Chloramphenicol is rarely used as a systemic

to near the pH of tears and they contain a pre-

drug nowadays, but it has been useful for many

servative, such as benzalconium chloride. It

years in the form of eye drops. It remains a drug

must be borne in mind that patients who

of choice in the UK for superficial eye infections.

develop an allergic reaction to drops might be

Other broad-spectrum antibiotics in use

reacting to the preservative. Single-application

include gentamycin, framycetin, tobramycin

containers are also used, which do not contain a

and neomycin, as well as ciprofloxacin and

preservative but are expensive.

ofloxacin. When an infection of the eye is sus-

Eye lotions are usually prescribed in 200 ml

pected, a culture is taken from the conjunctival

quantities and are used to irrigate the conjunc-

sac and treatment started with a wide-spectrum

tival sac. Sodium chloride eye lotion is used

antibiotic. Systemic and intravitreal administra-

in first aid to flush out foreign bodies or

tion might be needed if the infection is intra-

irritant chemicals. Fresh mains tap water is an

ocular. A number of antiviral drugs are now

adequate substitute.

available, but acyclovir in the form of Zovirax

One of the major drawbacks of using eye

ointment is the most widely used treatment of

drops is that, although high local concentrations

herpes simplex keratitis. The use of systemic

of the drug are achieved in the anterior segment

acyclovir and famcyclovir for herpes zoster

of the eye, little if any drug penetrates to the

ophthalmicus has made a great impact on the

posterior segment. Drops are, therefore, of little

severity of ocular complications.

195

196

Common Eye Diseases and their Management

to constrict the pupil and open up the closed

Drops That Widen the Pupil

drainage angle. Sometimes it is necessary to

constrict the pupil rapidly during the course of

The pupils can be dilated either by local block-

intraocular surgery and this is achieved by

ade of the parasympathetic pathway or by local

instilling acetylcholine directly into the anter-

stimulation of the sympathetic pathway.

ior chamber. Strong meiotics run the risk of

causing retinal detachment in susceptible indiv-

Parasympathetic Antagonists

iduals. Meiotics have been used to reverse

the effect of mydriatic drops used for fundus

Routine mydriasis to allow examination of the

examination, but this practice is no longer

fundus is best achieved by tropicamide 0.5% or

recommended as a routine because it is

1% drops because the effect lasts for only about

unnecessary and the symptoms of meiosis may

3 h. Cyclopentolate 1% (0.5% in babies) can last

make matters worse.

for 24 h, but because of its cycloplegic effect

(blockade of accommodation) is preferable for

the examination of children’s eyes when refrac-

Drugs in the Treatment of

tion is also needed. Dilating the pupil runs the

risk of inducing an attack of acute narrow-angle

Open-angle Glaucoma

glaucoma in a predisposed individual. Because

the vision could remain blurred, driving should

There has been a small revolution involving the

be avoided within the first 6-8 h after mydriasis.

type of eye drops used for the treatment of glau-

Atropine in drop form is a long-acting mydri-

coma in recent times. For years, the mainstay of

atic, which is used when it is necessary to

treatment was pilocarpine and the topical beta-

prevent or break down adhesions between iris

blockers, for example timolol, but the potential

and lens in acute iritis (posterior synechiae). It

systemic side effects of these drugs have led to

is also used in the treatment of amblyopia in

the introduction of other novel types of ocular

children. Its effect lasts for about seven days.

hypotensive agents. In general, these new

Allergic reactions are quite common and occa-

agents can be divided into alpha₂-adrenergic

sionally systemic absorption can cause central

agonists, carbonic anhydrase inhibitors and

nervous system symptoms of atropine toxicity.

prostaglandin analogues.

The production of aqueous humour can be

Sympathetic Agonist

reduced by either blockade of the beta-receptors

on the ciliary body epithelial cells (i.e., with a

Phenylephrine (5 or 10% drops) is a sympath-

beta-blocker) or by agonism of the alpha₂-

omimetic amine. It is used with a parasym-

receptors. Brimonidine and apraclonidine are

pathetic antagonist when extremely wide pupil

both alpha₂-receptor agonists and show good

dilation is required (e.g., for intraocular surgery

efficacy compared with timolol. A significant

or for peripheral retinal examination). There are

number of patients, however, do develop an

reports of severe acute hypertension after use of

allergy to these agents and this has limited their

10% drops.

widespread use. Acetazolamide was introduced

as a diuretic many years ago; although not a very

good diuretic, it has proved to be a potent ocular

Drops That Constrict the Pupil

hypotensive when given orally. Again because of

side effects its use has been restricted to short-

In the past, meiotics have been widely used for

term treatment. In

1995, dorzolamide was

the treatment of chronic open-angle glaucoma.

introduced and more recently, brinzolamide

Pilocarpine is available in 1%, 2%, 3% or 4%

has become available. These are also carbonic

solutions. Although it is effective in reducing

anhydrase inhibitors but they are available in

the intra-ocular pressure, the side effects of

drop form and are able to penetrate the cornea.

dimming of vision and accommodation spasm

Their ocular hypotensive effects are generally

can be disabling and mean that this treatment

not as great as topical beta-blockers but they are

has largely been superceded. Pilocarpine is still

useful as adjuvant agents. It has recently been

used in the treatment of acute glaucoma attacks

discovered that a second aqueous outflow route

Drugs and the Eye

197

exists in the eye - the uveoscleral route. It is

toms, and topical mast cell stabilisers (sodium

known that certain prostaglandins increase the

cromoglicate, nedocromil sodium and lodox-

flow of aqueous via this route and a number of

amide), which are useful in disease prevention

topical prostaglandin F2a analogues are now

if used regularly.The treatment of severe (sight-

available. Latanoprost, travoprost and bimato-

threatening) disease involves the use of courses

prost have all been shown to as effective as

of topical and occasionally oral steroids.

topical beta-blockers with minimal side effects.

All these medications have the problem of

compliance. Elderly patients may forget to instill

Local Anaesthesia in

drops on a regular basis. In some cases, even

Ophthalmology

instillation of three different glaucoma drops

fails to control the intraocular pressure. In these

Proxymetacaine (Ophthaine) is a useful short-

instances, the only sure way of lowering the

acting anaesthetic drop that is comfortable to

pressure is by glaucoma drainage surgery.

instill and so is particularly useful when exam-

ining children. Amethocaine and benoxinate are

also widely used but are longer-acting and sting

Drugs in the Treatment of

quite markedly. Local anaesthetic drops should

Acute Angle-closure

not be used as pain relievers on a long-term

basis because the anaesthetized cornea becomes

Glaucoma

ulcerated and severe infection of the eye can

occur. Lignocaine (1% or 2%) with or without

Angle-closure glaucoma is a surgical problem.

adrenaline is injected into the eyelids for lid

Once the acute attack has been aborted by the

surgery. Local anaesthesia for intraocular

use of intensive pilocarpine drops and Diamox,

surgery is obtained by topical drops, sub-

a small hole is made in the iris with the

Tenon’s injection, periorbital injection (outside

Yttrium-Aluminium-Garnet

(YAG) laser to

the cone of extraocular muscles) or sometimes

allow redirection of the flow of aqueous. In

retrobulbar injection (within the muscle cone)

many patients this provides a permanent cure.

of lignocaine. For a longer effect, this is some-

Beta-blockers may also be used during

times combined with marcaine.

the acute stage and more recently the alpha₂-

agonist apraclonidine has been shown to be a

useful adjunct.

Drugs and Contact Lenses

As a rule, contact lenses should not be worn

Drugs in the Treatment of

when the eye is being treated with drops. The

Allergic Eye Disease

exception is when the contact lenses themselves

are being used for some therapeutic purpose.

With the increasing incidence of atopy, the treat-

Soft hydrophilic contact lenses can take up and

ment of allergic eye disease has gained in

store the preservative from some kinds of drop.

importance in recent years. Treatments are

The preservative benzalkonium chloride is espe-

designed to interfere with either the type 1

cially liable to be absorbed onto a contact lens.

(immunoglobulin E [IgE]-mediated) or type 4

When it is essential that drops are administered

(delayed) hypersensitivity response, both of

to a patient wearing contact lenses, it is often

which are thought to be important in disease

possible to prescribe in the form of single-dose

pathogenesis. For mild disease, initial treatment

containers that do not contain a preservative.

should involve antigen avoidance (if known)

and frequent use of artificial tears (hypromel-

lose) to wash away antigens from the ocular and

Artificial Tears

conjunctival surface. Treatment of more severe

disease involves the use of systemic or topical

Artificial tears provide one of a number of meas-

antihistamines (levocabastine, emedastine and

ures that are used to treat tear deficiency. Other

azelastine), which are helpful for relief of symp-

measures include occlusion of the lacrimal

198

Common Eye Diseases and their Management

puncta or the use of mucolytic agents. The first

step is to make the diagnosis. Once a deficiency

of tears has been confirmed, the mainstay of

treatment is hypromellose.Adsorptive polymers

of acrylic acid can also give symptomatic relief.

Polyvinyl alcohol is another compound present

in a number of tear substitutes. Recently, a new

agent, sodium hyaluronate

(0.1%) has been

shown to improve symptom relief and improve

the ocular surface abnormalities in cases of

severe dry eye. By their nature, tear substitutes

tend to adhere to the surface of the eye and in

the conjunctival sac. For this reason, their pro-

longed use is liable to give rise to preservative

reactions. Preservative-free preparations are

often preferable. Some patients with a severe dry

eye problem might need to instill the drops

every hour or even more frequently.

Steroids give a patient a feeling

of well-being

Anti-inflammatory Drugs

and the Eye

Figure 24.1.

There might be a false impression of the real

benefit obtained.

Local steroids are widely used in the treatment

of eye disease; systemic steroids are not used

unless the sight of the eye is threatened. It must

Ophtha], ketorolac [Acular] and flurbiprofen

be remembered that systemic steroids give the

[Ocufen]) to reduce our dependence on topical

patient a sense of well-being, which might give

steroids. They have been shown to be of use in

a false impression of the real benefit obtained.

the treatment of postcataract surgery inflam-

Furthermore, systemic steroids can have serious

mation and in reducing the pain after excimer

and life-threatening side effects, such as ver-

laser surgery and corneal abrasions.

tebral collapse through osteoporosis and perfor-

ated gastric ulcer (Figure 24.1).

Local steroids should also be applied with

Anti-angiogenic Drugs

caution, and it is a good rule always to have a

specific reason for giving them.That is to say,they

and the Eye

should not be prescribed just to make red eyes

turn white without a clear diagnosis. The reasons

Uncontrolled angiogenesis

(growth of new

for this are two-fold: first, local steroids enhance

blood vessels) is a common finding in many

the multiplication of viruses, especially herpes

potentially blinding conditions, such as prolif-

simplex; and second, they can cause glaucoma in

erative diabetic retinopathy, central retinal vein

certain predisposed individuals. In such indiv-

occlusion, wet age-related macular degenera-

iduals, the instillation of one drop of steroid can

tion (ARMD) and retinopathy of prematurity.

cause a temporary rise of intraocular pressure.

Inhibiting their growth offers us the hope of

The most potent steroid in this respect is dexam-

dramatically reducing the number of patients

ethasone, followed by betamethasone, pred-

going blind each year. It is thought that the

nisolone and hydrocortisone. It has been claimed

angiogenic response is caused by elevated levels

that rimexolone, clobetasone and fluorometho-

of a cytokine called vascular endothelial growth

lone are relatively safe in this respect.

factor

(VEGF) produced by abnormal or

Recently, a number of nonsteroidal anti-

ischaemic cells within the eye. Attempts to

inflammatory drugs (NSAIDs) have been made

reduce the levels of VEGF and hence turn off the

available in topical form (diclofenac [Voltarol

angiogenic drive have involved intravitreal

Drugs and the Eye

199

injections of anti-VEGF antibodies or oligonu-

blindness. Certain antipsychotic drugs can also

cleotide aptamers, which bind VEGF, or the

cause fundus pigmentation in excessive doses;

intravitreal/sub-Tenon’s injection of an anti-

melleril and chlorpromazine have been incrim-

angiogenic steroid (triamcinolone). All of these

inated in this respect in the past. Recently, a

treatments are showing great promise in clini-

number of cases of uveitis have been reported

cal trials. An alternative mechanism of treat-

in patients using bisphosphonates for the treat-

ment is the destruction of preformed new

ment and prevention of osteoporosis. Interest-

vessels. Recently, a new type of treatment for wet

ingly, sudden visual loss has been reported

ARMD has seen the use of a light-activated dye,

in a number of patients taking the oral anti-

injected intravenously, which preferentially

inflammatory COX-2 inhibitors (celecoxib and

locates in the choroidal neovascular membrane

rofecoxib). The vision has returned to normal

(photodynamic therapy). Activation of the dye

upon cessation of treatment.

by light of a specific wavelength causes throm-

Apart from causing glaucoma in some

bosis and destruction of blood vessels harbour-

patients, systemic steroids are thought to

ing the dye. Treatment of patients with one

increase the rate of formation of cataracts.

particular subtype of wet ARMD (classic with

Ethambutol and isoniazid can cause optic

no occult blood vessels) has shown stabilisation

atrophy. Sometimes excessive doses of quinine

of vision in 60-70% of cases.

are taken as an abortifacient and as the patients

regain consciousness they are found to be blind

from quinine toxicity. Methyl alcohol is toxic to

the ganglion cells of the retina and blindness is

Damage to the Eyes by Drugs

a hazard of meths drinkers. It sometimes con-

Administered Systemically

taminates crudely prepared alcoholic beverages

leading to unexpected loss of vision. The list of

There are a number of drugs, which if given

drugs with ocular side effects is large and the

in excessive doses, can lead to severe visual

reader should consult a specialised textbook

handicap and blindness. Some of these are still

for more information. Nowadays, disasters and

available on prescription. Chloroquine and

indeed lawsuits should be avoidable if the drug

hydroxychloroquine in excessive doses can lead

literature is checked before prescribing an

to pigmentary degeneration of the retina and

unfamiliar drug.

Blindness

Blindness marks the failure or inefficacy of

tax concessions. Registration is usually initiated

ophthalmological treatment. Once a patient

in the hospital clinic. Some patients are referred

becomes permanently blind, he or she might be

by their general practitioners or social workers

lost from the care of the ophthalmologist. This

for registration by the ophthalmic specialist. A

means that the ophthalmologist might not have

special form is completed and copies go to the

personal experience of the size of the problem

patient, the general practitioner, the social serv-

and might not be in a position to experience the

ices department and the Office of Population

relative incidences of different causes of blind-

and Censuses.

ness. The keeping of accurate statistics is of

Certain guidelines are laid down when con-

great importance, and in order to keep statis-

sidering blind registration; the visual acuity

tical records it is necessary to have a clear

should be less than 3/60 in the worse eye but if

definition of blindness. Many people who dread

the field of vision is constricted, the visual

blindness imagine having no perception of light

acuity might be better than this. Patients whose

in each eye. Fortunately, this situation is uncom-

vision is not bad enough for blind registration

mon, but many people are severely debilitated

but none the less have significant visual handi-

by visual loss.

cap can have their name placed on the partially

In the UK, the major problem is among the

sighted register. In these patients the binocular

elderly where visual loss is often combined with

vision should normally be worse than 6/18.

defective hearing. Sensory deprivation is thus a

Patients sometimes erroneously claim the

major scourge at the present time; the problem

benefits of the partially sighted because they

is undoubtedly going to be much worse as the

have only one eye, even though the remaining

proportion of elderly people increases.

eye is normal. When the vision with one or both

eyes is 6/18 or better, the patient is not usually

considered to be partially sighted. When one eye

Definition

is completely lost through injury or disease, the

amount of incapacity is set for medicolegal pur-

In the UK, the statutory definition of blindness

poses at about 10%. In actual fact, the amount of

refers to persons who “are so blind as to be

incapacity depends a great deal on the age of the

unable to perform any work for which eyesight

patient.A child can adapt to a remarkable degree

is essential”. When a patient’s vision falls below

to being one-eyed, even to the extent of being

this level, registration as a blind person can be

able to perform with skill at ball games. Adults

considered. This is a voluntary process, which

who become one-eyed find difficulty in judging

allows the patient access to the social services

distances or performing fine manual tasks.

for the visually handicapped, as well as certain

More importantly, a number of occupations are

203

204

Common Eye Diseases and their Management

specifically barred to those whose vision is poor

ask for a report from an ophthalmologist or an

in one eye.

optometrist. Double vision is a bar to driving, if

it cannot be corrected by prisms in the glasses

or the wearing of an eye patch.

Benefits for the Visually

Handicapped

Colour Blindness

There is no blind pension in the UK but those

This is not blindness in any sense of the word and

registered blind have a special income tax

indeed some colour-blind individuals are

allowance and some exemptions from deduc-

unaware of any problem until their colour vision

tions from income support. Blind persons can

is tested. Of the male population, 8% suffers from

have parking concessions and a free National

some form of congenital colour blindness. This

Health Service (NHS) sight test, as well as rail

is usually in the form of “red-green blindness”.

cards and bus passes. Disability living allowance

Inheritance of this type of defect is sex-linked so

can be available for blind people under the age of

that unaffected female carriers pass the gene

65 years but for the over-65s, only those who are

to 50% of their sons. The screening of school

both blind and deaf can qualify. Those seeking

children for colour blindness is now widely

these concessions should consult an expert in the

practiced because of the occupational implica-

field. There are a number of voluntary organisa-

tions. The Ishihara test is the simplest and the

tions that run clubs, social centres and supply

best test for congenital colour blindness. Occu-

various other aids and benefits. For example, the

pations that entail the reading of coloured

Royal National Institute for the Blind (RNIB)

warning lights or the matching of colours usually

provides a comprehensive range of services

demand some form of colour vision test on entry.

including the popular talking-book service. It

It is an advantage to the child to be aware of any

also supplies regular funds for research into the

defect during the early years of schooling.

causes of blindness.

The system of registration applies equally to

children. In this instance, registration calls

Incidence and Causes

attention to the need for special educational

of Blindness

requirements. These can include a specialist

resource teacher, low visual aids, and other

In England and Wales, the prevalence of blind-

special supplies and equipment. If necessary,

ness in 1980 for children under five years was

special schooling might need to be considered.

9:100,000.This figure increased to 2324:100,000

for adults over 75 years. In the western world,

blindness in children is largely because of inher-

Standards of Vision for

ited genetic disease and birth trauma. In adults

Various Occupations

aged 20-60 years, the major causes are diseases

of the retina, including diabetic retinopathy and

The standards for various occupations can vary

optic atrophy. Over the age of 60 years, macular

from year to year and are more or less exacting,

degeneration, glaucoma and cataract are the

depending on the occupation. In the UK, in

important problems.

order to drive a private motor vehicle, one must

In Africa and Asia, the causes of blindness are

be able, in good daylight, to read a number plate

rather different; many children become blind

with glasses or contact lenses at

67 feet or

from corneal scarring associated with vitamin

20.5 m.A full binocular field of vision is also now

A deficiency and measles. Cataract is the most

required. This must extend at least 120° horizon-

important cause in adults but in certain areas,

tally and

20° above and below. The field is

for example southern Sudan, onchocerciasis

measured by perimetry using a standard target.

and trachoma are still a serious problem.

It is assumed that any healthy person applying

It is apparent that the problems of blindness

to drive has a normal field of vision but if the

in Europe and North America are different from

driver has any eye condition that might lead to

those in poorer parts of the world where much

visual handicap, he or she must declare it. The

could still be done by improving standards of

driver and vehicle licensing centre might then

nutrition and living conditions.

Blindness

205

skin and even by means of implanted electrodes

Aids for the Blind

in the visual cortex.

The most widely recognised aid and symbol of

One important advance has been voice

blindness is the white stick. It is also one of the

synthesis by computers. Many current models

most useful aids because it identifies the patient

have this facility, so that the user can hear

as blind and encourages others to give assis-

emails, and programmes are available to allow

tance. Many blind people are concerned that

printing in Braille. In spite of these advances, the

they appear ill-mannered when failing to recog-

elderly visually handicapped patient can benefit

nise someone and are grateful for some indica-

most from someone who is prepared to give the

tion of their handicap.

time to read out letters or books. Some volun-

Many different electronic devices have been

tary local societies can provide this service.

tried but by and large these are only useful to

When the patient has a visual acuity of better

younger patients who can make full use of them.

than 6/60, much can be achieved by the use of

Scanning systems are now available which,

optical magnification. An ordinary hand mag-

when moved across the page, can read out the

nifying glass is the simplest and can often be the

page. Most blind patients are unable to afford

most effective form of assistance. If this is not

this type of aid. Many of these devices rely on

adequate and the patient has been a keen reader,

the patient’s hearing to identify an audible

a telescopic lens can be fitted to a spectacle

warning signal, but most blind people prefer to

frame with advantage. These multi-lens systems

use their undistracted sense of hearing as an

are known as low visual aids and hence the

important clue to their whereabouts.

popular “LVA” clinics in eye departments for the

Guide dogs are specially trained by the Guide

testing and provision of these items. Apart from

Dogs for the Blind Society and the patient must

special telescopic lenses, closed-circuit televi-

also take part in the training. Some young

sion aids are now available: a small television

people find that a guide dog can expand their

camera is held over the page and a magnified

mobility to a great degree.

view of the written material is presented on a

Certain tactile aids are also useful, the best

television screen.

known of which is Braille. This system of

The well-being of a blind or partially sighted

reading for the blind was introduced from

person can be greatly enhanced by relatively

France more than 100 years ago. The letters of

simple social measures. Advice in the home

the alphabet are represented by numbers of

about the use of gas or electricity can be impor-

raised dots on stiff paper. Blind children can

tant and the patient can be made aware of the

learn Braille rapidly and develop a high reading

availability of local social clubs for the blind or

speed. Some adults find that their fingers are not

keep-fit classes and bus outings. An elderly

sufficiently sensitive and this applies especially

patient who plays the piano can be helped

to diabetics. Books in Braille are now available

by the provision of an enlarged photocopy

in many different languages. Tape recordings of

of a favourite piece of music. In spite of all

books and newspapers are now very popular

these various possibilities, one must not for-

among blind and partially sighted people of

get that the simplest and most useful reading

all ages. The Talking-Book Service provides a

aid for a partially sighted person is a good

comprehensive library for the use of the

light directed onto the page. The distance of

visually disabled.

the bulb from the page is as important as the

There are numerous other gadgets that can

wattage of the bulb.

be helpful to the blind and partially sighted;

a popular one is the device that can indicate

whether a teacup is full or not. For those with

some residual vision, a special telephone pad

Artificial Eyes

with large numbers on it can be helpful. Other

ingenious devices range from relief maps that

These can be made of glass or plastic molded

can be felt by the blind person, to a telephone

to the shape of the eye socket and painted to

that speaks back through the earpiece the digit

match the other eye. Usually they are removed

that has just been pressed. Research has also

and washed at night by the patient and replaced

been carried out on aids that signal the position

the following morning. A slight degree of dis-

of objects by means of electrical stimuli to the

charge from the socket is the rule but excessive

206

Common Eye Diseases and their Management

discharge can indicate that the socket is becom-

Surgical removal of an eye (enucleation) is con-

ing infected. This, in turn, might be because of

sidered in the following circumstances:

roughening of the artificial eye with wear. Under

these circumstances, arrangements should be

• when the eye is blind and painful

made for the prosthesis to be replaced or pol-

• when the eye contains a malignant tumour

ished. It should always be borne in mind that a

• when the eye is nearly blind and sym-

patient with an artificial eye might have had the

pathetic ophthalmitis is a risk following a

eye removed because it contained a malignant

perforating injury.

tumour, in which case one must consider the

possibility of local or systemic spread of the

tumour. A well-made artificial eye is almost

Before having an eye removed, the patient

undetectable to the untrained eye but normal

must be made fully aware of all the advantages

movements of the eye can be restricted. Nowa-

and disadvantages. A general anaesthetic is

days, the use of orbital prostheses deep to the

needed and the patient remains in hospital for

conjunctiva and attached to the eye muscles gives

one to two nights after the operation. It is

greatly increased movement. After many years

common practice to fit the socket with a trans-

and after renewing the artificial eye on several

parent plastic “shell” for a few weeks until the

occasions, the eye can appear to sink downwards.

artificial eye is fitted.

Index

changes in eye, 149-150

Anti-inflammatory drugs, 198

Acanthamoeba, 55

external eye, 149-150

Antiangiogenic drugs, 198-199

Accommodation, 14, 30, 67, 81, 95,

globe, 150

Aqueous humor, 13-14

113, 139, 158, 161, 178, 182,

eye disease in elderly, 150-156

Arcuate scotoma, 94

186, 196

eyelid deformities, 153-154

Arcus senilis, 50, 57, 150

Acquired immune deficiency

glaucoma, 153

Artificial eyes, 205-206

syndrome, 176-178

macular degeneration, age-

Artificial tears, 197-198

neoplasms, 177

related, 150-153

Atopic conjunctivitis, 49

neuro-ophthalmological signs,

management, 151-153

Autoimmunity in uveitis,

177-178

stroke, 154-155

147-148

noninfectious retinopathy, 177

temporal arteritis, 154

management, 148

ophthalmological signs,

AIDS. See Acquired immune

Autosomal dominant inheritance,

177-178

deficiency syndrome

191

opportunistic infections, 177

Aids for blind, 205

Autosomal recessive inheritance,

Acuity testing, 137-140

Albinism, 159-160, 190, 192

191

Acute angle closure glaucoma,

Allergic conjunctivitis, 49

97-100, 197

Allergic eye disease, 197

acute attack, 98

Amblyopia of disuse, 113, 161

Bacterial conjunctivitis, 46-47

pathogenesis, 97

Anatomy of eye, 7-16

Band degeneration, 57-58, 78

signs, 98-99

Anemia, 174

Basal cell carcinoma, 43,

subacute attack, 97-98

Anesthesia, 197

124-125

symptoms, 97-98

Aniridia, 160

Benign vascular tumors of

treatment, 99-100

Anterior chamber, contusion, 130

eyelids, 124

Acute glaucoma, 63-64

Anterior uveitis, 141-144

Binocular vision, 5, 111-112, 116,

Acute hemorrhagic conjunctivitis,

causes, 143

118, 161

complications, 143

Blepharitis, 41

Acute iritis, 64

heterochromic iridocyclitis, 144

Blepharospasm, 38-39

Acute keratitis, 64

pars planitis, 144

Blindness, 203-207

Adenoviral conjunctivitis, 48

signs, 141-143

aids for blind, 205

Adnexae, tumors of, 121-128

sympathetic ophthalmia,

artificial eyes, 205-206

Age, effect on retinal blood

143-144

causes of, 204

vessels, 172

symptoms, 141

color blindness, 204

Aging eye, 149-156

treatment and management,

defined, 203-204

cataract, 153

144

incidence, 204

209

210

Index

Blindness (cont.)

epicanthus, 159

causes, 46

occupational standards of

examination, 157-158

chlamydial conjunctivitis,

vision, 204

globe, structural abnormalities,

47-48

visually handicapped, 204

160-161

conjunctival culture, 46

Blood pressure, effect on retinal

aniridia, 160

herpes simplex

vessels, 172-173

congenital cataract, 160-161

conjunctivitis, 48

Blood supply of eye, 10

juvenile macular degeneration,

infective agents, 49

Bowman’s layer, 8

162-163

microscopy, 46

Bruch’s membrane, 9, 14, 150-151

lacrimal obstruction, 159

secondary conjunctivitis,

Brushfield’s spots, 193

leucocoria, 161

50-51

Buphthalmos, 101, 160

nystagmus, congenital, 159-160

signs, 46

albinism, 160

symptoms, 45

motor congenital nystagmus,

trachoma, 48

Capillary hemangioma of

159

corneal foreign body, 36, 51-53,

newborn, 124

sensory congenital

129, 158

Career in ophthalmology, 5

nystagmus, 159

signs and symptoms, 51-52

Cataract, 81-90, 153

spasmus nutans, 160

treatment, 52-53

age, 82

Ophthalmia neonatorum, 162

subconjunctival hemorrhage,

congenital factors, 84

optic atrophy, 162

contusion, 83

phakomatoses, 163

Conjunctival tumors, 125-126

diabetes, 82-83

ptosis, 159

benign lesions, 125-126

etiology, 82-84

refraction abnormalities, 161

benign pigmented lesions,

lens, 81-82

retinopathy of prematurity,

125-126

management, 86-89

161-162

malignant lesions, 126

opthalmoscopy, 85-86

screening, 158-159

melanoma of conjunctiva,

perforation, 83

squint, 161

126

radiation, 83-84

uveitis, 162

nonpigmented lesions, 126

secondary causes, 83

Chlamydial conjunctivitis, 47-48

Conjunctivitis, 45-51, 61-63

to disease elsewhere, 83

Choroid, contusion, 131

acute conjunctivitis, 62

to disease in eye, 83

Choroidal melanoma, 121-122

causes, 46

signs, 85-86

Choroidal metastases, 122

chronic conjunctivitis, 62-63

slit-lamp microscopy, 86

Chromosomal abnormalities, 190,

conjunctival culture, 46

surgery, 87

193

microscopy, 46

age of patient, 87

Ciliary body, 14

signs, 46

cataract operation, 88

Color blindness, 204

symptoms, 45

convalescence, 89

Color vision, 19

Contact lenses, 77-78, 197

time spent in hospital, 89

Congenital albinism, 160

cosmetic, 78

traumatic cataract, 87-88

Congenital cataract, 160-161

indications, 78

symptoms, 84-85

Congenital glaucoma, 101-102

side-effects, 77-78

toxicity, 84

Congenital motor congenital

therapeutic, 78

trauma, 83-84

nystagmus, 159

types, 77

visual acuity reduction, 85

Congenital sensory congenital

Contusion, 129-131

Cavernous hemangioma, 124, 127

nystagmus, 159

anterior chamber, 130

Central retinal vein thrombosis,

Congenital spasmus nutans, 160

choroid, 131

68, 100

Conjunctival disease, 45-60

cornea, 129-130

Cerebrospinal fluid, 71-72

conjunctivitis, 45-51

iris, 130-131

Chalazion, 123

acute hemorrhagic

lens, 131

Chemical injuries, 134

conjunctivitis, 48

optic nerve, 131

Childhood squint, 112-116

adenoviral conjunctivitis,

retina, 131

Child’s eye, 157-164

vitreous, 131

adult eye, contrasted, 157

allergic conjunctivitis, 49

Cornea, 13

amblyopia of disuse, 161

bacterial conjunctivitis,

contusion, 129-130

congenital eye defects, 159-161

46-47

layers, 8

Index

211

transparency

signs and symptoms, 106-107

parasympathetic antagonists,

anatomical, 13

tractional retinal detachment,

196

physiological, 13

104

sympathetic agonist, 196

Corneal disease, 45-60

Diabetes, 82-83, 100, 165-170

systemically-administered

absent corneal sensation, 58-59

anterior chamber, 166

drug, damage to eyes by,

corneal degenerations, 57-58

background retinopathy, 167

199

corneal dystrophies, 57

control of, 169

Dry eye, 36-37

corneal edema, 58

cornea, 165-166

causes, 36

corneal ulceration, 53-57

diabetic maculopathy, 168-169

management, 37

corneal ulcer, 53-57

diffuse edema, 168-169

Schirmer’s test, 36-37

Corneal nerve supply, 56

focal, 168

signs, 36-37

Corneal ulcer, 53-57

ischemic, 169

slit-lamp examination, 36

bacteria, 54-55

eyelids, 165

tear film break-up time, 37

direct trauma, 53-54

glaucoma surgery, 170

Cortical connections, 11

iris, 166

Cosmetic contact lenses, 78

laser photocoagulation,

Ectropion, 38

Cryobuckle, 109

169-170

Emboli, 174

Cytomegalovirus retinitis, 177

lens, 166

Endophthalmitis, 148

ocular movements, 165

Endothelium, eye, 8

preproliferative stage, 167-168

Entropion, 38

Dacryocystitis, acute, 35-36

prognosis, 170

Epicanthus, 37-38, 159

Deformities of eyelids, 37-40

proliferative retinopathy, 168

Episcleritis, 63, 148

blepharospasm, 38-39

retina, 167

Examination of eye, 17-26

ectropion, 38

treatment, 169

color vision, 19

entropion, 38

vitreo-retinal surgery, 170

external eye, 20-21

epicanthus, 37-38

Diplopia. See Double vision

glasses, 19-20

ingrowing eyelashes, 39-40

Double vision, 18, 41, 84, 112, 118,

globe, 21-22

lagophthalmos, 38

127, 154, 172, 186-188

initiation of, 20-22

normal eyelid, 37

blow-out fracture of orbit, 188

lids, 20-21

ptosis, 39

causes of, 187-188

ophthalmoscope use, 22-24

causes, 39

eye movement assessment, 187

pupil evaluation, 20

redundant lid skin, 39

fourth cranial nerve palsy, 188

tests, 25-26

Dendritic ulcer, 55-56

myasthenia gravis, 188

visual acuity, 17-19

Dermoid cyst, 42-43, 127

ocular muscle imbalance, 187

visual field, 19

Descemet’s membrane, 8

sixth cranial nerve palsy,

Exophthalmos, 127-128

Detachment, retinal, 103-110

187-188

External eye, 20-21

exudative retinal detachment,

third cranial nerve palsy, 188

Extraocular muscle anatomy,

104

thyrotoxicosis, 188

116-117

flashes, 106

Drops constricting pupil, 196

Extraocular muscles, 12

incidence, 103

Drops widening pupil, 196

Exudative retinal detachment,

pathogenesis, 103-104

Drugs, 195-200

104, 107

classification, 104

acute angle closure glaucoma,

Eyelashes, ingrowing, 39-40

rhegmatogenous retinal

197

Eyelid deformities, 37-40,

detachment, 104-106

allergic eye disease, 197

153-154

breaks in retinal detachment,

anti-inflammatory drugs, 198

blepharospasm, 38-39

104-105

antiangiogenic drugs, 198-199

ectropion, 38

mechanism of, 105-106

artificial tears, 197-198

entropion, 38

posterior vitreous

contact lenses, 197

epicanthus, 37-38

detachment, 105

drops constricting pupil, 196

ingrowing eyelashes, 39-40

retinal breaks formation, 105

drops widening pupil, 196

lagophthalmos, 38

retinal degeneration, 105

infection treatment, 195

normal eyelid, 37

with trauma, 106

local anesthesia, 197

ptosis, 39

vitreous, 105

open angle glaucoma, 196-197

redundant lid skin, 39

212

Index

Eyelid disease, 33-44

Fluorescein angiography, 18, 121,

signs, 93-94

allergic disease of eyelids, 43

152, 169

symptoms, 93

dry eye, 36-37

Fusion, 111, 160

treatment, 95-96

causes, 36

secondary glaucoma, 100-101

management, 37

to abnormalities in lens, 101

Schirmer’s test, 36-37

Ganglion cells, axons of, 11

drug-induced glaucoma, 101

signs, 36-37

Genetic abnormalities, 190

to trauma, 101

slit-lamp examination, 36

Genetics, 189-194

to tumors, 100-101

tear film break-up time, 37

autosomal dominant

to uveitis, 100

infections of eyelids, 40-41

inheritance, 191

to vascular disease in eye,

blepharitis, 41

autosomal recessive

100

meibomian gland infection,

inheritance, 191

surgery, 170

chromosomal abnormalities,

Glioma of optic nerve, 127

Molluscum contagiosum, 41

190, 193

Globe, 7-8, 21-22

orbital cellulitis, 41

genetic abnormalities, 190

anterior chamber, 7

styes, 40-41

genetic mechanisms, 190

anterior segment, 8

lid injuries, 43-44

mitochondrial inheritance, 193

aqueous humor, 7

lid tumors, 41-43

multifactorial diseases, 193

blood, 8

benign tumors, 41-43

multiple genes, 190

coats of, outer fibrous layer, 7

malignant tumors, 43

sex-linked recessive

compartments of, 7

watering eye, 33-36

inheritance, 192-193

inner nervous layer, 7

tear drainage, 33-36

Giant cell arteritis, 72-73, 154

intraocular fluids, 7

tear secretion, 36

Glasses, 19-20

middle vascular layer, 7

Eyelid injury, 133

measuring for, 139-140

outer fibrous layer, 7

Eyelid tumor, 123-125

automated refraction,

posterior chamber, 7

basal cell carcinoma, 124-125

139-140

posterior segment, 8

benign tumors, 123-124

objective refraction, 139

segments, 8

benign vascular tumors of

subjective refraction, 139

structural abnormalities,

eyelids, 124

Glaucoma, 91-102, 153

160-161

capillary hemangioma of

acute angle closure glaucoma,

aniridia, 160

newborn, 124

97-100

congenital cataract, 160-161

cavernous hemangioma, 124

acute attack, 98

uveal tract, 7

Kaposi sarcoma, 124

natural history, 97

vitreous chamber, 7

keratoacanthoma, 123

pathogenesis, 97

vitreous humor, 7-8

malignant tumors of eyelids,

signs, 98-99

Globe injuries, 129-133

124-125

subacute attack, 97-98

contusion, 129-131

meibomian cysts, 123

symptoms, 97-98

anterior chamber, 130

melanoma of eyelid, 125

treatment, 99-100

choroid, 131

Molluscum contagiosum, 123

clinical types, 92-102

cornea, 129-130

papilloma, 123

congenital glaucoma, 101-102

iris, 130-131

sebaceous gland carcinoma,

developmental glaucoma,

lens, 131

125

101-102

optic nerve, 131

seborrhoeic keratosis, 123

intraocular pressure

retina, 131

senile keratosis, 123

maintenance of, 91-92

vitreous, 131

squamous cell carcinoma, 125

measurement of, 92

perforation, 131-133

telangiectatic hemangioma, 124

normal, 91

intraocular foreign body, 132

xanthelasma, 123

neovascular, 64-65

sympathetic ophthalmia,

Eyelids, 11-13

normal pressure glaucoma, 97

132-133

management, 97

Globe tumors, 121-123

primary open angle glaucoma,

choroidal melanoma, 121-122

Facial skeleton abnormalities, 114

92-96

choroidal metastases, 122

Flashes, 106

natural history, 93

melanoma of iris, 122-123

Floaters, 106

pathogenesis, 93

retinoblastoma, 122

Index

213

Gonioscopy, 99, 101

Inflamed eye, 141-148

Laser photocoagulation, 169-170

Grave’s disease, 170

anterior uveitis, 141-144

Lens, 14

causes, 143

contusion, 131

complications, 143

Leucocoria, 161

Hay fever conjunctivitis, 49

heterochromic iridocyclitis,

Leukemias, 174-175

Headache, 71-76

144

Lid tumors, 41-43

blood, 73

pars planitis, 144

benign tumors, 41-43

blood vessels, 72-73

signs, 141-143

dermoid cyst, 42-43

bones, 73-74

sympathetic ophthalmia,

hemangioma, 42

cerebrospinal fluid, 71-72

143-144

nevus, 42

classification, 71

symptoms, 141

papilloma, 41-42

drugs, 75

treatment and management,

xanthelasma, 43

eyes, 74

144

malignant tumors, 43

meninges, 74

autoimmunity in uveitis,

basal cell carcinoma, 43

nerves, 73

147-148

squamous cell carcinoma, 43

pain, referred, 74-75

management, 148

Local anesthesia, 197

patient history, 71

endophthalmitis, 148

Long sight, 29-32

post-traumatic headache, 75

episcleritis, 148

Lymphoproliferative disease, 128

Hemangioma, 42, 128

panophthalmitis, 148

Hemorrhage, subconjunctival, 45

posterior uveitis, 144-147

Herpes simplex conjunctivitis, 48

causes, 145

Macular degeneration, age-

Herpes simplex keratitis, 55-56

presumed ocular

related, 150-153

Herpes zoster ophthalmicus,

histoplasmosis, 147

management, 151-153

59-60

sarcoidosis, 146-147

Maddox rod, 118

Hess screen, 118

signs, 145

Maddox wing, 117-118

Heterochromic iridocyclitis, 144

symptoms, 144-145

Malignant hypertension, 173

Histoplasmosis, 147

syphilis, 147

Malignant tumors of eyelids,

Horizontal recti, 116

toxocariasis, 146

124-125

Hypertension

toxoplasmosis, 145-146

Meibomian gland infection, 40

age, effect on retinal blood

tuberculosis, 146

Melanoma of conjunctiva, 126

vessels, 172

scleritis, 148

Melanoma of eyelid, 125

blood pressure, effect on retinal

Inner layer of eye, 9

Melanoma of iris, 122-123

vessels, 172-173

Intermediate uveitis, 144

Meninges, 74

malignant hypertension, 173

Intraocular foreign body, 132

Metastatic tumors, 127

vascular changes associated

Iris, contusion, 130-131

Middle layer of eye, 9

with, 173-174

Ischemic optic neuropathy, 174

Mitochondrial inheritance, 193

emboli, 174

Molluscum contagiosum, 41

ischemic optic neuropathy,

Motor congenital nystagmus, 159

174

Juvenile macular degeneration,

Mucocele of sinuses, 128

retinal vascular occlusion,

162-163

Multifactorial diseases, 193

173

Multiple genes, 190

Hypopyon, 54, 142-143

Multiple sclerosis, 183-184

Kaposi sarcoma, 124

internuclear ophthalmoplegia,

Keratic precipitates, 142

183-184

Idiopathic orbital inflammatory

Keratoacanthoma, 123

nystagmus, 183

disease, 127

Keratoconus, 30, 49, 57, 78

ocular findings, 183-184

Infections of eyelids, 40-41

optic neuritis, 183

blepharitis, 41

retrobulbar neuritis, 183

meibomian gland infection,

Lacrimal apparatus, 12-13

Lacrimal gland tumor, 127

Molluscum contagiosum, 41

Lacrimal obstruction, 159

Neovascular glaucoma, 64-65

orbital cellulitis, 41

Lacrimal passageway, 33-35

Neuro-ophthalmology, 179-188

styes, 40-41

Lagophthalmos, 38

double vision, 186-188

214

Index

Neuro-ophthalmology (cont.)

Onchocerciasis, 175-176

rhabdomyosarcoma, 127

blow-out fracture of orbit,

extraocular features, 176

sac tumor, 127

188

management, 176

Outer layer of eye, 8-9

causes of, 187-188

ocular features, 176

basement membrane,

eye movement assessment,

Opaque media, 113

epithelium, 8

187

Open angle glaucoma, 196-197

Bowman’s layer, 8

fourth cranial nerve palsy,

Ophthalmia neonatorum, 162

cornea layers, 8

188

Ophthalmoscope use, 22-24

Descemet’s membrane, 8

myasthenia gravis, 188

Opportunistic infections, 177

endothelium, 8

ocular muscle imbalance, 187

Opthalmoscopy, 85-86

epithelium, and its basement

sixth cranial nerve palsy,

Optic atrophy, 162

membrane, 8

187-188

Optic disc, 179-183

stroma, 8

third cranial nerve palsy, 188

atrophy, optic, 180-181

thyrotoxicosis, 188

causes of, 181

multiple sclerosis, 183-184

following disease in optic

Pain, referred, 74-75

internuclear

nerve, 181

Painful eye

ophthalmoplegia, 183-184

following papilledema, 181

failing vision, 63-65

nystagmus, 183

glaucoma, 181

normal vision, 63

ocular findings, 183-184

inherited, 181

scleritis, 63

optic neuritis, 183

toxic, 181

Papilledema, 182

optic disc, 179-183

trauma, 181

Papilloma, 41-42, 123

atrophy, optic, 180-181

vascular causes, 181

Parasympathetic antagonists, 196

central cup, 180

Pars planitis, 144

color, 179

Perforation, 131-133

congenital disc anomalies,

congenital disc anomalies, 180

intraocular foreign body, 132

180

hemorrhages, 180

sympathetic ophthalmia,

hemorrhages, 180

margins, 179

132-133

margins, 179

normal, 179-180

Phakomatoses, 163

normal, 179-180

pale disc, 180-181

Photopsiae, 106

pale disc, 180-181

swelling, 181-183

Physiology of eye, 7-16

swelling, 181-183

optic neuritis, 182

accommodation, 14

vessel entry, 179

postoperative, 182

aqueous humor, 13-14

pupil abnormalities, 185-186

true papilledema, 182

ciliary body, 14

constricted pupil, 186

vascular, 181-182

circular fibers, 14

dilated pupil, 186

vessel entry, 179

longitudinal fibers, 14

visual field defects, 184-185

Optic nerve, 10-11

cornea, 13

Nevus, 42

axons of ganglion cells visual,

eyelids, 13

Noninfectious retinopathy, 177

lens, 14

Nonpigmented lesions, 126

contusion, 131

retina, 14-15

Normal pressure glaucoma, 97

cortical connections, 11

neuroretina, 14

management, 97

papillary reflex pathways, 11

RPE, 14-15

Nystagmus, congenital, 159-160

retina, 11

tear film, 13

albinism, 160

subcortical centers, relays, 11

vitreous body, 14

motor congenital nystagmus,

visual pathways, 11

Pingueculum, 50, 126

159

Orbital cellulitis, 41

Polycythemia, 50, 63, 73

sensory congenital nystagmus,

Orbital injuries, 133

Post-traumatic headache, 75

159

Orbital tumors, 127-128

Posterior uveitis, 144-147

spasmus nutans, 160

cavernous hemangioma, 127

causes, 145

dermoid cyst, 127

presumed ocular

glioma of optic nerve, 127

histoplasmosis, 147

Occupational standards of vision,

lacrimal gland tumor, 127

sarcoidosis, 146-147

204

metastatic tumors, 127

signs, 145

Ocular muscle imbalance, 119

pseudotumor, 127

symptoms, 144-145

Index

215

syphilis, 147

painful eye, normal vision, 63

with trauma, 106

toxocariasis, 146

scleritis, 63

vitreous, 105

toxoplasmosis, 145-146

painless, normal vision, 61-63

Rubella, 84, 102, 160

tuberculosis, 146

subconjunctival hemorrhage,

Rubeosis iridis, 100, 166, 170

Postherpetic neuralgia, 73

Presbyopia, 14, 29, 74, 81, 84, 138,

Redundant lid skin, 39

150

Refraction abnormalities, 161

Sarcoidosis, 146-147

Primary open angle glaucoma,

Retina, 14-15

Schirmer’s test, 36-37

92-96

contusion, 131

Schlemm’s canal, 91, 93

pathogenesis, 93

neuroretina, 14

Sebaceous gland carcinoma, 125

signs, 93-94

Retinal detachment, 103-110

Seborrhoeic keratosis, 123

symptoms, 93

exudative retinal detachment,

Secondary conjunctivitis, 50-51

treatment, 95-96

104, 107

Secondary glaucoma, 100-101

Proliferative retinopathy, 168

flashes, 106

to abnormalities in lens, 101

Proptosis, 127-128

floaters, 106

drug-induced glaucoma, 101

assessment of, 128

incidence, 103

to trauma, 101

causes of, 128

management, 107-110

to tumors, 100-101

hemangioma, 128

pathogenesis, 103-104

to uveitis, 100

infection, 128

classification, 104

to vascular disease in eye, 100

lymphoproliferative disease,

prognosis, 109-110

central retinal vein

128

prophylaxis, 107-108

thrombosis, 100

mucocele of sinuses, 128

retinal surgery, 108-109

diabetes, 100

pseudoproptosis, 128

cryobuckle, 109

Senile keratosis, 123

pseudotumor, 128

vitrectomy, 109

Sensory congenital nystagmus,

thyrotoxicosis, 128

rhegmatogenous retinal

159

trauma, 128

detachment, 104-106

Sex-linked recessive inheritance,

Pseudoproptosis, 128

breaks in retinal detachment,

192-193

Pseudotumor, 127-128

104-105

Shadow, 106-107

Ptosis, 39, 159

mechanism of, 105-106

Short sight, 29-32

causes, 39

posterior vitreous

Sickle-cell disease, 175

Pupil abnormalities, 185-186

detachment, 105

Slit-lamp examination, 36, 86

constricted pupil, 186

retinal breaks formation, 105

Spectacles. See Glasses

dilated pupil, 186

retinal degeneration, 105

Spring catarrh, 49-50

Pupil evaluation, 20

with trauma, 106

Squamous cell carcinoma, 43, 125

vitreous, 105

Squint, 111-120, 161

shadow, 106-107

in adults, 116-118

Radiation, 83-84

signs and symptoms, 106-107

amblyopia of disuse, 113

Radiational injuries, 134

tractional retinal detachment,

causes of, 113, 117

Red eye, 61-66

104, 107

in childhood, 112-116

conjunctivitis, 61-63

Retinal vascular occlusion, 173

diagnosis, 114, 117-118

acute conjunctivitis, 62

Retinoblastoma, 122

examination, 114-115

chronic conjunctivitis, 62-63

Retinopathy of prematurity,

extraocular muscle anatomy,

episcleritis, 63

161-162

116-117

failing vision, 67-69

Rhabdomyosarcoma, 127

horizontal recti, 116

fundus abnormal, 68

Rhegmatogenous retinal

obliques, 116-117

fundus normal, 67-68

detachment, 104-106

vertical recti, 116

treatable causes of, 69-70

breaks in retinal detachment,

facial skeleton abnormalities,

untreatable causes of, 70

104-105

114

painful, failing vision, 63-65

mechanism of, 105-106

fusion, 111

acute glaucoma, 63-64

posterior vitreous detachment,

glasses, 115

acute iritis, 64

105

Hess screen, 118

acute keratitis, 64

retinal breaks formation, 105

history, 114

neovascular glaucoma, 64-65

retinal degeneration, 105

Maddox rod, 118

216

Index

Squint (cont.)

Stycar test, 18-19, 138, 157

malignant hypertension, 173

Maddox wing, 117-118

Styes, 40-41

vascular changes associated

management, 115-116

Subconjunctival hemorrhage, 45

with, 173-174

muscle weakness, 113-114

Subcortical centers, relays, 11

leukemias, 174-175

ocular muscle imbalance, 119

Supporting structures of eye,

onchocerciasis, 175-176

opaque media, 113

7-13

extraocular features, 176

optic nerve disease, 113

Sympathetic agonist, 196

management, 176

orthoptic follow-up, 115-116

Sympathetic ophthalmia, 132-133,

ocular features, 176

refractive error, 113

143-144

sickle-cell disease, 175

retinal disease, 113

Synoptophore, 111

thyroid eye disease, 170-172

simultaneous macular

Syphilis, 147

chemosis, 171

perception, 111

Systemic disease, 165-178

exposure keratitis, 171

stereopsis, 111

acquired immune deficiency

extraocular muscle action

surgery, 116

syndrome, 176-178

limitation, 172

synoptophore, 111

neoplasms, 177

lid lag, 171

treatment, 118

neuro-ophthalmological

lid retraction, 171

types of, 112

signs, 177-178

lid swelling, 171

Stereopsis, 111

noninfectious retinopathy,

management, 172

Strawberry nevus, 124

177

optic nerve compression,

Stroke, 154-155

ophthalmological signs,

172

Stroma, 8

177-178

proptosis, 171

Structure of eye, 7-13

opportunistic infections, 177

Systemically-administered drug,

blood supply, 10

anemia, 174

damage to eyes by, 199

extraocular muscles, 12

diabetes, 165-170

eyelids, 11-12

anterior chamber, 166

globe, 7-8

background retinopathy,

Tear drainage, 33-36

blood, 8

167

acute dacryocystitis, 35-36

coats of, outer fibrous layer,

conjunctiva, 165-166

lacrimal passageway, 33-35

control of, 169

Tear film, 13

compartments of, 7

cornea, 165-166

break-up time, 37

inner nervous layer, 7

diabetic maculopathy,

Tear secretion, 36

intraocular fluids, 7

168-169

Telangiectatic hemangioma,

middle vascular layer, 7

eyelids, 165

124

posterior chamber, 7

glaucoma surgery, 170

Temporal arteritis, 154

posterior segment, 8

iris, 166

Testing visual acuity, 137-140

segments, 8

laser photocoagulation,

glasses, measuring for, 139-140

vitreous chamber, 7

169-170

automated refraction,

vitreous humor, 7-8

lens, 166

139-140

inner layer, 9

ocular movements, 165

objective refraction, 139

lacrimal apparatus, 12-13

preproliferative stage,

subjective refraction, 139

middle layer, 9

167-168

Tests of visual acuity, 25-26

optic nerve, 10-11

prognosis, 170

Thyroid eye disease, 170-172

axons of ganglion cells

proliferative retinopathy,

exposure keratitis, 171

visual, 11

168

lid lag, 171

cortical connections, 11

retina, 167

lid retraction, 171

subcortical centers, relays, 11

treatment, 169

lid swelling, 171

visual pathways, 11

vitreo-retinal surgery, 170

Thyrotoxicosis, 128

outer layer of eye, 8-9

vitreous, 167

Toxicity, 84

Bowman’s layer, 8

hypertension, 172-174

Toxocariasis, 146

cornea layers, 8

age, effect on retinal blood

Toxoplasmosis, 145-146

Descemet’s membrane, 8

vessels, 172

Trachoma, 48

endothelium, 8

blood pressure, effect on

Tractional retinal detachment,

stroma, 8

retinal vessels, 172-173

104, 107