Ophthalmology Lecture Notes PDF - Twelfth Edition

WEBFTOC 09/16/2016 1:7:56 Page vi WEBFFIRS 09/16/2016 0:6:46 Page i Ophthalmology Lecture Notes WEBFFIRS 09/16/2016 0:6:46 Page ii This title is also available as an e-bo...

WEBFTOC 09/16/2016 1:7:56 Page vi WEBFFIRS 09/16/2016 0:6:46 Page i Ophthalmology Lecture Notes WEBFFIRS 09/16/2016 0:6:46 Page ii This title is also available as an e-book. For more details, please see www.wiley.com/buy/9781119095903 WEBFFIRS 09/16/2016 0:6:46 Page iii Ophthalmology Lecture Notes Twelfth Edition Bruce James MA, DM, FRCS (Ed), FRCOphth Consultant Ophthalmologist Department of Ophthalmology Stoke Mandeville Hospital Buckinghamshire and School of Medicine, St. George’s University, Grenada, West Indies Anthony Bron BSc, FRCOphth, FARVO, FMedSci Professor Emeritus Nuffield Laboratory of Ophthalmology University of Oxford, Oxford Professor of Experimental Ophthalmology, Vision and Eye Research Unit, Anglia Ruskin University, Cambridge Manoj V. Parulekar MS, FRCS (Ed), FRCOphth Consultant Ophthalmologist Birmingham Children’s Hospital and Oxford University Hospitals NHS Trust WEBFFIRS 09/16/2016 0:6:46 Page iv This edition first published 2017  2017 by Bruce James, Anthony Bron and Manoj V Parulekar Previous editions 1960, 1965, 1968, 1971, 1974, 1980, 1986, 1997, 2003, 2007, 2011 Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988. 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No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom. Library of Congress Cataloging-in-Publication Data Names: James, Bruce, 1957- author. | Bron, Anthony J., author. | Parulekar, Manoj V., author. Title: Lecture notes. Ophthalmology / Bruce James, Anthony Bron, Manoj V. Parulekar. Other titles: Ophthalmology Description: 12th edition. | Chichester, West Sussex ; Hoboken, NJ : John Wiley & Sons, Inc., 2017. | Includes bibliographical references and index. Identifiers: LCCN 2016026509 (print) | LCCN 2016027367 (ebook) | ISBN 9781119095903 (pbk.) | ISBN 9781119095927 (pdf) | ISBN 9781119095941 (epub) Subjects: | MESH: Eye Diseases | Handbooks | Problems and Exercises Classification: LCC RE50 (print) | LCC RE50 (ebook) | NLM WW 39 | DDC 617.7–dc23 LC record available at https://lccn.loc.gov/2016026509 A catalogue record for this book is available from the British Library. 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Set in 8.5/11pt UtopiaStd-Regular by Thomson Digital, Noida, India 1 2017 WEBFTOC 09/16/2016 1:7:56 Page v Contents Preface to twelfth edition, vii Preface to first edition, ix Acknowledgements, xi Abbreviations, xiii About the companion website, xv 1 Anatomy, 1 2 History, symptoms and examination, 19 3 Clinical optics, 44 4 The orbit, 50 5 The eyelids, 56 6 The lacrimal system, 63 7 Conjunctiva, cornea and sclera, 69 8 The lens and cataract, 84 9 Uveitis, 92 10 Glaucoma, 102 11 Retina and choroid, 116 12 Retinal vascular disease, 133 13 The pupil and its responses, 145 14 Disorders of the visual pathway, 150 15 Eye movements and their disorders, 161 16 Trauma, 175 17 Tropical ophthalmology: eye diseases in the developing world, 184 18 Eye diseases in children, 195 19 Services for the visually handicapped, 205 20 Clinical cases, 208 Useful references, 217 Appendix 1: Conversion table for representation of visual acuity, 219 Appendix 2: Drugs available for ophthalmic use, 220 Index, 223 WEBFTOC 09/16/2016 1:7:56 Page vi FPREF02 09/16/2016 1:4:1 Page vii Preface to twelfth edition Welcome to the twelfth edition of Ophthalmology Lec­ astigmatism and restoring near and distance vision in ture Notes! As in the past, our aim has been to make the some patients without the need for glasses. Vitreor­ diagnosis and management of eye disease a palatable etinal surgery employs inert gases and silicone oil to process and once again we stress the value of a good flatten the detached retina and endoscopic probes history and careful clinical examination of the eye. which allow manipulations in the vitreous space and The eye is remarkably accessible. Optical and digital the dissection of microscopic membranes from the techniques continue to develop giving increasingly retinal surface. Glaucoma surgery is developing tiny detailed access to the structures of the eye at cellular drainage implants to reduce intraocular pressure. level. Specular microscopy can image the corneal Despite these advances, most ophthalmic diag­ endothelial cells which regulate corneal hydration noses can still be made from a good history and and transparency; optical coherence tomography clinical examination of the eye. This book aims to allows the layers of the retina to be dissected and teach skills which will be useful to anyone engaged in recently allows the retinal vasculature to be imaged medical practice. Many systemic disorders have ocu­ without the need for injection of fluorescein. Confocal lar features which are critical in diagnosis. This book microscopy provides a three-dimensional view of the covers the ophthalmic features of systemic hyper­ optic nerve head. The shape of the cornea can be tension, diabetes, sarcoidosis, endocarditis, demyeli­ plotted digitally and, outside the globe, orbital struc­ nating disease and space-occupying lesions of the tures and the visual pathway can be viewed by brain. It also explains how to recognize iritis, distin­ neuroimaging. guish various forms of retinopathy and understand the Therapeutically, lasers are used to relieve acute, difference between papilloedema and papillitis. angle closure glaucoma, to lower ocular pressure in As in the eleventh edition, each chapter provides a chronic glaucoma, to open up an opaque lens capsule set of learning objectives and a summary of key points, following cataract surgery and to seal retinal holes. as well as bullet lists for emphasis. You can test your They have an established role in reshaping the cornea understanding with the questions and picture quizzes to treat refractive errors of the eye and their role is now at the end of each chapter. In this edition, we have extending to use in cataract surgery itself. Sight-threat­ updated all the chapters and added to the extended ening diabetic retinopathy can be treated effectively matching questions (EMQs) and multiple choice by retinal photocoagulation, to remove the angiogenic questions to bring this small volume up to date. stimulus to vasoproliferation. More recently, it has Chapter 20 offers classical case histories, which will become possible to inhibit new vessel formation in let you test your diagnostic skills. The final section of diabetic retinopathy, macular degeneration and other the book provides a list of further reading and the retinal vascular disorders by intravitreal injections of details of attractive websites which offer an expanded antiangiogenic drugs. Roles for these drugs in treating view of the speciality. Try some of these out. oedema of the retina, see for example in diabetes, are We hope that you will have as much fun reading also becoming established. these Lecture Notes as we did putting them together. These techniques are matched by technological innovations in microsurgery, responsible for dramatic Bruce James advances in cataract and vitreoretinal surgery. Optical Anthony Bron function in cataract surgery is restored by insertion of Manoj V. Parulekar a lens which unfolds within the eye. These are becom­ ing increasingly complex allowing for the treatment of FPREF02 09/16/2016 1:4:1 Page viii WEBFPREF01 09/16/2016 1:0:26 Page ix Preface to first edition This little guide does not presume to tell the medical classify a long succession of ocular structures, all of student all that he needs to know about ophthalmol­ which emerged as isolated brackets for yet another ogy, for there are many larger books that do. But the sub-catalogue of small and equally isolated diseases. medical curriculum becomes yearly more congested, Surely it is time now to try and harness these miscel­ while ophthalmology, still the ‘Cinderella’ of medi­ laneous ailments, not in terms of their diverse mor­ cine, is generally left until the last, and only too readily phology, but in simpler clinical patterns; not as the goes by default. So it is to these harassed final-year microscopist lists them, but in the different ways that students that the book is principally offered, in the eye diseases present. For this, after all, is how the sincere hope that they will find it useful; for nearly all student will soon be meeting them. eye diseases are recognized quite simply by their I am well aware of the many inadequacies and appearance, and a guide to ophthalmology need be omissions in this form of presentation, but if the little more than a gallery of pictures, linked by lecture belaboured student finds these lecture notes at least notes. more readable, and therefore more memorable, than My second excuse for publishing these lecture notes the prolix and time-honoured pattern, perhaps I will is a desire I have always had to escape from the be justified. traditional textbook presentation of ophthalmology as a string of small isolated diseases, with long Patrick Trevor-Roper unfamiliar names, and a host of eponyms. To the nineteenth-century empiricist, it seemed proper to WEBFPREF01 09/16/2016 1:0:26 Page x WEBFACKN 09/15/2016 23:54:54 Page xi Acknowledgements Numerous colleagues have provided valuable advice Thanks are due also to Karen Moore and the staff at in their specialist areas, for which we are most grateful. Wiley Blackwell for their encouragement, efficiency The authors wish to thank Tom Meagher and Ramona and patience during the production of this edition. We Khooshabeh for providing additional pictures for the are also grateful to Shikha Pahuja and the copyediting twelfth edition. Tom Butler provided substantial input team of Thomson Digital, for meticulous reading and to the chapter on clinical optics. We are particularly production of the text. grateful to Professor Allen Foster at the London School of Hygiene and Tropical Medicine, who kindly pro­ Bruce James vided the illustrations for the chapter on tropical Anthony Bron ophthalmology. Richard James, Chris King and Ajay Manoj V Parulekar Mohite worked on the questions and assessments. WEBFACKN 09/15/2016 23:54:54 Page xii WEBFABBRE 09/15/2016 23:43:17 Page xiii Abbreviations AIDS acquired immunodeficiency syndrome LASEK laser-assisted subepithelial keratomileusis AION anterior ischaemic optic neuropathy LASIK laser-assisted in situ keratomileusis AMD age-related macular degeneration LGB lateral geniculate body ARM age-related maculopathy MLF medial longitudinal fasciculus CCTV closed circuit television MRA magnetic resonance angiogram CMV cytomegalovirus MRI magnetic resonance imaging CNS central nervous system NSAID non-steroidal anti-inflammatory drug CRVO central retinal vein occlusion OCT optical coherence tomogram CSF cerebrospinal fluid PAS peripheral anterior synechiae CT computed tomography PEE punctate epithelial erosions DCR dacryocystorhinostomy PHMB polyhexamethylene biguanide ENT ear, nose and throat PMN polymorphonuclear leucocyte ERG electroretinogram PPRF parapontine reticular formation ESR erythrocyte sedimentation rate PRK photorefractive keratectomy GCA giant cell arteritis PS posterior synechiae GI gastrointestinal PVR proliferative vitreoretinopathy GPC giant papillary conjunctivitis RAPD relative afferent pupil defect HAART highly active anti-retroviral therapy RPE retinal pigment epithelium HIV human immunodeficiency virus TB tuberculosis HLA human leucocyte antigen TNF tumour necrosis factor HSV herpes simplex UV ultraviolet ICG indocyanine green angiography VA visual acuity INR international normalized ratio VEGF vascular endothelial growth factor IOL intraocular lens VKH Vogt–Koyanagi–Harada disease KP keratic precipitate WEBFABBRE 09/15/2016 23:43:17 Page xiv WEBFABOUT 09/15/2016 23:50:29 Page xv About the companion website Don’t forget to visit the companion website for this book: www.lecturenoteseries.com/ophthalmology There you will find valuable material designed to enhance your learning, including: Interactive MCQs Interactive EMQs Figures from the book Scan this QR code to visit the companion website. WEBFABOUT 09/15/2016 23:50:29 Page xvi WEBC01NEW 09/16/2016 10:12:46 Page 1 1 Anatomy Learning objective ✓ To learn the anatomy of the eye, the orbit and the third, fourth and sixth cranial nerves, as a background to the medical conditions affecting them. just medial to the medial orbital rim. It acts as the Introduction palpebral sphincter (Figure 1.2). Like all other muscles of the face, it is supplied by the seventh cranial nerve. Contraction of its orbital part results Knowledge of ocular anatomy and function is impor­ in protective, forced eye closure, while contraction tant to the understanding of eye diseases. A brief of its palpebral part is employed in the downstroke outline is given below. of the upper lid during a blink. The levator palpe­ brae muscle, the elevator of the upper lid (see below), is concerned with the upstroke of the blink Surface anatomy of the (third cranial nerve). These synchronized contrac­ tions are completed within just 300 ms. The con­ face tents of the orbit are separated from those of the lid by a connective tissue sheet, or orbital septum, The eyes are disposed symmetrically about the face which extends from the orbital rim to the tarsal and their forward-looking arrangement permits a plate, deep to orbicularis. large overlap in visual fields, the basis of stereopsis. Lying within the bony orbits, they are protected from trauma by the orbital walls and rims and by the eye­ lids, by blinking and eye closure. With the eyes open and looking straight ahead, all but the upper and lower Sensory innervation of the corneal margins are exposed in the palpebral aperture, face: the fifth cranial together with two small white triangles of bulbar conjunctiva, overlying the sclera. The medial and nerve lateral ends of the fissure are known as the medial The sensory innervation of each half of the face is and lateral canthi (Figure 1.1). provided by the trigeminal nerve (Figure 1.3). The The lids and the upper and lower orbital rims are eye, upper lid, eyebrow, forehead and nose are overlain by the orbicularis muscle which sweeps supplied by its ophthalmic division (V1), via its over these structures in an ellipse, from a region lacrimal, frontal and nasociliary branches, which enter the orbit through the superior orbital fissure. The maxillary division (V2), lying inferolaterally to Ophthalmology Lecture Notes, Twelfth Edition. V1 in the cavernous sinus, exits the cranial cavity via Bruce James, Anthony Bron and Manoj V. Parulekar. the foramen rotundum and, at the inferior orbital © 2017 Bruce James, Anthony Bron and Manoj V. Parulekar. Published 2017 by John Wiley & Sons, Ltd. fissure, gives rise to the infraorbital and zygomatic Companion Website: www.lecturenoteseries.com/ophthalmology nerves. These supply, chiefly, the lower lid and the WEBC01NEW 09/16/2016 10:12:46 Page 2 2 Anatomy Figure 1.1 The eye, looking straight ahead. upper lip and cheek. The mandibular division (V3), exiting the skull via the foramen ovale, supplies the lower lip, chin and jaw and the preauricular skin and temporal region. It is also motor to the muscles of mastication. The neurons of the three divisions of the trigem­ inal nerve converge upon the trigeminal ganglion, whose sensory roots enter the pons to be distrib­ uted to the trigeminal nuclei in the brainstem. The mesencephalic nucleus is concerned with propri­ oception, the main sensory nucleus with touch and the medullary nucleus of the spinal tract with pain and temperature sensibility. Fibres from the ophthalmic division go to the lowest part of this nucleus, those from the mandibular division to its Figure 1.2 Disposition of the orbicularis is muscle. highest part. Figure 1.3 Sensory innervation of the face by the trigeminal nerve. WEBC01NEW 09/16/2016 10:12:48 Page 3 Anatomy 3 The space between the cornea anteriorly and the Gross anatomy of the eye iris and central lens posteriorly, filled with aque­ ous humour, is the anterior chamber, whose The eye comprises (Figure 1.4): periphery is the iridocorneal angle or drainage angle. The angle gives access to a meshwork of A tough, collagenous outer coat which is transpar­ cells and collagen beams called the trabecular ent anteriorly (the cornea) and opaque posteriorly meshwork, through which aqueous drains into (the sclera). The junction between them is called the Schlemm’s canal and thence into the venous limbus. The extraocular muscles attach to the outer system via the aqueous veins. This is the basis sclera, while the optic nerve leaves the globe of aqueous drainage. posteriorly. Between the iris, lens and ciliary body lies the A rich vascular coat (the uvea) forms the choroid posterior chamber, a narrow space distinct from posteriorly and the ciliary body and iris anteriorly. the vitreous body behind. Both the anterior and Internal to the choroid lies the retina, to which it is posterior chambers are filled with aqueous humour. firmly attached and whose outer two-thirds it Between the lens and the retina lies the vitreous nourishes. body, occupying most of the posterior segment of The ciliary body contains the smooth ciliary muscle, the eye. The posterior segment refers to the poste­ whose contraction controls focusing by altering lens rior two-thirds of the eye, lying behind the anterior shape. The lens lies behind the iris, supported by the vitreous face. The anterior segment comprises all zonules, whose fine fibres run from the lens equator those structure lying anterior to the vitreous. to the ciliary body. When the eye is focused for distance, tension in the zonule maintains a flattened Anteriorly, the bulbar conjunctiva of the globe profile of the lens. When the ciliary body contracts, passes from the limbus into the fornices of the tension is relaxed, the lens takes up a more curved conjunctival sac and thence onto the posterior shape and focusing for near objects is achieved. surface of the lids, where it becomes the tarsal The ciliary body also provides attachment for the conjunctiva. A connective tissue layer (Tenon’s iris, which forms the pupillary diaphragm. The capsule) separates the conjunctiva from the sclera ciliary epithelium secretes aqueous humour and and is prolonged backwards as a sheath around the maintains the ocular pressure. rectus muscles. Figure 1.4 The basic anatomy of the eye. WEBC01NEW 09/16/2016 10:12:48 Page 4 4 Anatomy The orbit The eyelids (the tarsus) The eye, or globe, lies within the bony orbit, which has The eyelids (Figure 1.6): the shape of a four-sided pyramid (Figure 1.5). At its posterior apex is the optic canal, which transmits the offer mechanical protection to the globe; optic nerve to the chiasm, tract and lateral geniculate spread the tears over the conjunctiva and cornea body. The superior and inferior orbital fissures trans­ with each blink. mit the blood vessels and cranial nerves that supply The levator muscle is the main elevator of the the orbital structures. The lacrimal gland lies anteri­ upper lid. It passes forwards from an attachment orly in the superolateral aspect of the orbit. On the on the sphenoid bone, above the optic foramen, to anterior part of the medial wall lies the fossa for the an aponeurosis which inserts into the tarsal plate. lacrimal sac. It is innervated by the third cranial nerve. Damage Figure 1.5 The anatomy of the orbit. Figure 1.6 The anatomy of the eyelids. WEBC01NEW 09/16/2016 10:12:51 Page 5 Anatomy 5 Figure 1.7 Drawing of the eye: (a) in cross section, (b) in frontal view to illustrate the distri­ bution of the tears. (Source: Gaffney EA et al. Progress in Retinal and Eye Research 2010; 29(1):59–78. Reproduced with permission of Elsevier.) to the nerve or weakening of the aponeurosis in old age results in drooping of the upper eyelid (ptosis). A flat, smooth muscle, (the superior tarsal, or Müller’s muscle) innervated by the sympathetic nervous sys­ tem, arises from the deep surface of the levator and inserts into the tarsal plate. Müllers muscle also con­ tributes to a lesser extent to elevation of the lid, and if the sympathetic supply is damaged, a slight ptosis results as part of Horner’s syndrome. Each eyelid comprises: an anterior layer of skin; the palpebral part of the orbicularis muscle; a tough collagenous layer (the tarsal plate) which houses the meibomian oil glands; an epithelial lining, the tarsal conjunctiva; the lash-bearing, lid margins. Figure 1.8 Diagram of lid margin to show meibomian orifices, meniscus and tear film lipid layer (TFLL). (Source: The tarsal conjunctiva is reflected, via the fornices, Bron et al. Ocul Surf 2011; 9(2):70–91. Reproduced with onto the anterior surface of the globe, where it permission of Elsevier.) becomes the bulbar conjunctiva. When the eyes are closed, this lining forms the conjunctival sac, which contains the tears. When the eyes open, a tear film is margin, just anterior to the mucocutaneous junction. formed which covers and protects the exposed cornea This oil spreads onto the anterior surface of the tear and conjunctiva. At the lid margins, the tear film is film with each blink, to form a lipid layer, which bordered by the tear menisci (Figure 1.7). retards evaporation and stabilizes the tear film. The lid margins exhibit a narrow, posterior con­ junctival zone, continuous with the tarsal conjunctiva and a cutaneous zone anteriorly, which bears the lashes. These zones are separated by the muco­ The lacrimal drainage cutaneous junction which forms the anterior bound­ system ary of each tear meniscus (Figure 1.8). At the medial ends of each lid margin, dipping into a lake of tears at Tears drain into the upper and lower puncta and then the nasal canthus, are the lacrimal puncta, through into the lacrimal sac via the upper and lower canaliculi which tears drain from the tear menisci into the (Figure 1.9). They form a common canaliculus before lacrimal drainage system. entering the lacrimal sac. The nasolacrimal duct The meibomian oil glands, embedded in the tarsal passes from the sac to the nasal cavity which enters plates (Figure 1.8), deliver their oil to the skin of the lid at the inferior meatus. Failure of the distal part of the WEBC01NEW 09/16/2016 10:12:53 Page 6 6 Anatomy Figure 1.9 The major components of the lacrimal drainage system. nasolacrimal duct to fully canalize at birth is the usual Functions of the tear film cause of a watering, sticky eye in an infant. Tear It moistens the eye, preventing dehydration of its drainage is an active process. Each blink helps to surface. pump tears through the system. It provides a smooth, air/tear, optical interface for distortion-free refraction of light at the cornea. It transmits oxygen to the avascular cornea. Detailed functional It removes debris and foreign particles from the anatomy ocular surface through the flow and drainage of the tears and the action of the blink. It has antibacterial properties by means of lysozyme, The tear film lactoferrin, defensins and the immunoglobulins, The eye is bathed constantly by the tears, secreted by the particularly secretory IgA. lacrimal gland into the upper fornix of the conjunctival The tear film is replenished with each blink. sac. There is a small contribution from the conjunctiva. Tears are lost from the surface in part by evaporation and in part by drainage via the nasolacrimal system. The cornea Lacrimal secretion is under parasympathetic control The cornea is 0.5 mm thick and comprises through a feedback loop from the cornea, via the tri­ (Figure 1.10): geminal nerve, to the superior salivatory nucleus and The epithelium, an anterior, non-keratinised squa­ thence to the lacrimal gland. This ensures that tear mous layer, five cells thick, thickened peripherally at production is regulated reflexly in response to signals the limbus where it is continuous with the conjunc­ from the ocular surface. tiva. The limbus houses the germinative stem cells The most superficial epithelial cells of the ocular which maintain the corneal epithelium. The basal surface express a mucin-rich glycocalyx which renders cells of the epithelium are firmly attached to an the surface wettable. When the eyes are open, the underlying basal lamina by hemidesmosomes and exposed ocular surface is covered by a tear film, 3 μm by anchoring fibrils which extend into Bowman’s thick. This has two layers: layer. A mucoaqueous layer containing gel mucin from the An underlying stroma which accounts for over conjunctival goblet cells and aqueous tear fluid from 90% of the corneal thickness. On its most anterior the lacrimal gland, directly in contact with the aspect is a tough, anterior limiting layer (Bow­ ocular surface. man’s layer), 20 μm thick, which is free of cells A thin surface oil layer (100 nm) produced by the and composed of fine, short, tightly interwoven meibomian glands and delivered to the tear film collagen fibrils. The main body of the stroma from the lid margins. consists of type I collagen fibrils arranged in WEBC01NEW 09/16/2016 10:12:54 Page 7 Anatomy 7 Figure 1.10 The structure of the cornea and precorneal tear film (schematic, not to scale – the stroma accounts for 95% of the corneal thickness). parallel within lamellae, each fibril surrounded by a is rapidly repaired by cell spreading and proliferation. ground substance rich in proteoglycans. Between the Endothelial damage by disease or surgery is repaired lamellae are scattered keratocytes which, like fibro­ by cell spreading alone, with a loss of cell density. blasts, engage in stromal maintenance and repair. When cell density falls below a critical level, a loss of The anterior lamellae lie in the plane of the cornea, while posteriorly they have a more woven arrange­ ment. The regular packing of the collagen fibrils, their small diameter and narrow separation (in the region of 200 nm) accounts for corneal transparency. Backscattered light, towards the source, is obliter­ ated by destructive interference and over 90% of the light is transmitted. This orderly architecture is maintained by regulating stromal hydration. The stroma is bounded behind by the posterior limiting layer (Descemet’s layer), the basal lamina of the corneal endothelium. It is chiefly composed of type IV collagen. The endothelium, a monolayer of hexagonal, non- regenerating cells (Figure 1.11) which actively pump ions from the stroma into the anterior cham­ ber carrying water with them. This controls corneal hydration and thickness and hence transparency. The difference between the regenerative capacity of the epithelium and endothelium is important. Dam­ Figure 1.11 Normal corneal endothelium shown by age to the epithelial layer, by an abrasion, for example, confocal microscopy. (Courtesy of Paula Hedges.) WEBC01NEW 09/16/2016 10:12:56 Page 8 8 Anatomy Figure 1.12 The rela­ tionship between the choroid, RPE and retina. barrier and pumping functions leads to corneal over- It is loosely attached to the sclera. hydration (oedema), stromal swelling, disruption of It has a remarkably high blood flow. the regular packing of the collagen fibrils and to It nourishes the deep, outer two-thirds of the corneal clouding. The effect on vision is compounded retina and may have a role in its temperature by an associated epithelial oedema. homeostasis. The nutrition of the cornea is supplied almost Its basal lamina, together with that of the retinal entirely by the aqueous humour, which circulates pigment epithelium (RPE), forms the acellular through the anterior chamber and bathes the posterior Bruch’s membrane that acts as a diffusion barrier surface of the cornea. The aqueous also supplies oxy­ between the choroid and the retina which facilitates gen to the posterior stroma, while the anterior stroma the passage of nutrients and metabolites between receives its oxygen from the ambient air. The oxygen the retina and choroid. supply to the anterior cornea is reduced but still suffi­ cient during lid closure; however, a too tightly fitting contact lens may deprive the anterior cornea of oxygen, The retina causing epithelial oedema and visual loss. The retina (Figure 1.13) is a highly complex structure derived embryologically from the primitive optic cup. Functions of the cornea Its outermost layer is the RPE while its innermost layer forms the neuroretina, consisting of the photorecep­ It protects the internal ocular structures. tors (rods and cones), the bipolar nerve layer (and the Together with the lens, it refracts and focuses light amacrine and horizontal nerve cells) and the ganglion onto the retina. The junction between the ambient cell layer, whose axons give rise to the innermost, air and the curved surface of the cornea, covered by nerve fibre layer. These nerve fibres converge to the the optically smooth tear film, forms a powerful optic nerve head, where they form the optic nerve. refractive interface. The sclera The sclera is formed from interwoven collagen fibrils lying within a ground substance and main­ tained by fibroblasts. Because of the coarse weave and the variation in fibril width, the sclera scatters light strongly and appears white and opaque. It is of variable thickness, 1 mm around the optic nerve head and 0.3 mm just posterior to the rectus muscle insertions. The choroid The choroid (Figure 1.12) is a vascular layer formed of arterioles and venules and a dense, fenestrated capillary network, fused with the basal lamina of the Figure 1.13 The structure of the retina. (Courtesy of retina. Professor John Marshall.) WEBC01NEW 09/16/2016 10:12:57 Page 9 Anatomy 9 Müller cells, the principal glial cells of the retina, light. Different subgroups of cones are responsive to extend across its thickness and are vital for the health short, medium and long wavelengths (red, green of the retinal neurons. and blue,). They are concentrated at the fovea, where they provide the high resolution required The retinal pigment epithelium (RPE) for detailed vision, as in reading. Rods are responsible for night vision. They have a It is consists of a single layer of cells. low light threshold and do not signal wavelength It is loosely attached to the neuroretina, except at the information (colour). They form the large majority periphery (ora serrata) and around the optic disc. of photoreceptors in the remaining retina. It forms microvilli which project between and embrace the outer segment discs of the rods and cones. The vitreous It phagocytoses the redundant, pigment-containing discs, which are replaced by new ones. The vitreous is a clear gel occupying two-thirds of It takes part in the regeneration of rhodopsin and the globe. cone opsin, the photoreceptor visual pigments and It is 98% water. The remainder is gel-forming hyal­ in recycling vitamin A. uronic acid traversed by a fine collagen network. It contains melanin granules which absorb light There are few cells. scattered by the sclera, thereby enhancing image It is firmly attached anteriorly to the peripheral formation on the retina. retina, pars plana and around the optic disc, and less firmly to the macula and retinal vessels. It has a physically supportive role and permits the The photoreceptor layer passage of nutrients and metabolites. The photoreceptor layer is responsible for convert­ Loss of gel structure in later life, with collapse of the ing light into electrical impulses. The initial integra­ vitreous away from the retina (vitreous detachment), tion of these impulses is also performed by the puts traction on points of attachment and may occa­ retina. sionally lead to a peripheral retinal break or hole, where Cones (Figure 1.14) are responsible for daylight and the vitreous pulls off a flap of the underlying retina. This colour vision and have a relatively high threshold to is a risk factor for subsequent retinal detachment. Figure 1.14 The struc­ ture of the retinal rods and cones (schematic). WEBC01NEW 09/16/2016 10:12:57 Page 10 10 Anatomy The ciliary body ciliary muscle is responsible for changes in lens thickness and curvature during accommodation The ciliary body (Figure 1.15) is subdivided into three (see below). parts: 1 the ciliary muscle; The ciliary processes (pars plicata) 2 the ciliary processes (pars plicata); 3 the pars plana, located posteriorly. There are about 70 radial ciliary processes arranged in a ring around the posterior chamber. They are responsible for the secretion of aqueous humour. The ciliary muscle Each ciliary process is formed by an epithelium, two This comprises smooth muscle arranged in a ring layers thick (the outer pigmented and the inner non­ overlying the ciliary processes. pigmented) with a vascular stroma. It is innervated by the parasympathetic system via The stromal capillaries are fenestrated, allowing the third cranial nerve. plasma constituents ready access. The lens of the eye is suspended from the ciliary The tight junctions between the non-pigmented muscle by the ciliary zonule. Contraction of the epithelial cells provide a barrier to free diffusion Figure 1.15 The anatomy of the ciliary body. WEBC01NEW 09/16/2016 10:12:59 Page 11 Anatomy 11 into the posterior chamber. They are essential for Fluid passes into Schlemm’s canal, both through the active secretion of aqueous by these cells. giant vacuoles in its endothelial lining and through The epithelial layers show marked infolding, which intercellular spaces. increases their surface area for fluid and solute transport. The lens The pars plana Function This comprises a relatively avascular stroma cov­ The lens is the second major refractive element of the ered by an epithelial layer, two cells thick. eye; the cornea being the first. It is a perfectly transparent It is safe to make surgical incisions through the structure that lies directly behind the iris and pupil, scleral wall in this region to gain access to the suspended from the ciliary body by the fibres of the vitreous cavity. ciliary zonule (Figure 1.17). The zonular fibres insert into the lens equator, transmitting forces generated by the ciliary muscle to the lens, to change its shape and The iris refractive power. This allows focusing to be adjusted from distance to near. At rest, during distance viewing, The iris diaphragm is attached peripherally to the the zonular fibres are under tension, giving the lens a anterior part of the ciliary body. flattened profile. Contraction of the muscle during It is perforated centrally by the pupil, which is accommodation for near, relaxes the zonule and permits dilated or constricted by contraction of the circular the elasticity of the lens to increase its curvature and sphincter or radial dilator muscles, respectively, to hence its refractive power. This may seem counter- control the amount of light entering the eye. intuitive, but it comes about because the muscle bulges It has an anterior border layer of fibroblasts and inwards and moves forwards during contraction. collagen and a cellular stroma in which the sphinc­ ter muscle is embedded at the pupil margin. The sphincter muscle is innervated by the para­ Anatomy sympathetic system. The lens comprises an outer, tough, collagenous The smooth dilator muscle extends from the iris capsule. periphery towards the sphincter. It is innervated by A compact inner mass of lens fibre cells. the sympathetic system. Posteriorly, the iris is lined by a pigmented epithe­ The capsule is the basal lamina of the lens epithe­ lium two layers thick. lium, a monolayer of cells that lies between the cap­ sule and the lens fibres anteriorly. The anterior part of the capsule increases in thickness throughout life but The iridocorneal (drainage) angle synthesis of the posterior part ceases after birth, so it is This lies between the iris, the anterior tip of the thinner and more fragile. This is important during ciliary body and the cornea. It is the site of aqueous cataract surgery. drainage from the eye via the trabecular meshwork The epithelial cells at the lens equator form a (Figure 1.16). germinative zone, where cell division gives rise to the lens fibres that make up the bulk of the lens. Fibres are elongated, spindle-shaped cells arranged The trabecular meshwork in layers which arch over the lens equator. Anteriorly This overlies Schlemm’s canal and is composed of a and posteriorly, their tips meet to form the lens which lattice of collagen beams covered by trabecular cells. increase in complexity as the lens ages (Figure 1.18). The spaces between these beams become increas­ The high concentration of lens-specific proteins ingly small as Schlemm’s canal is approached. The within the fibres (the lens crystallins), accounts for outermost zone of the meshwork accounts for most the high refractive index of the lens. Their molecular of the resistance to aqueous outflow. Damage here order, together with the regular packing of the lens raises the resistance and increases intraocular pres­ fibres, accounts for its perfect transparency. sure in primary open-angle glaucoma. Some of the The lens grows throughout life, as shells of new spaces may be blocked and there is a reduction in fibres are laid down at the surface of the fibre mass. the number of cells covering the trabecular beams Thus, the oldest, central fibres that form the lens (see Chapter 10). nucleus represent the fetal lens and the fibres external WEBC01NEW 09/16/2016 10:12:59 Page 12 12 Anatomy Figure 1.16 The anatomy of the trabecular meshwork. to this that make up the lens cortex are all laid down accommodative power which reaches its peak at postnatally. For this reason, the depth of a lens opacity around 50 years. This is termed presbyopia. may provide a clue to its time of formation. Crystallin cross-linking, formation of high molecular With age, the deeper fibres lose their nuclei and weight aggregates and additional post-translational intracellular organelles and become inert, so the modifications to proteins, including pigmentation, metabolic work to maintain lens transparency is pro­ also lead to a steady loss of lens transparency, particu­ vided entirely by the lens epithelium and the youn­ larly affecting the lens nucleus, which at some point gest, most superficial fibres. It is remarkable that these may amount to cataract. deeper lens fibres, which are essentially dead, retain their transparency into late life. However, over the life span, there is progressive cross-linking of the lens The optic nerve crystallins leading to increasing stiffness of the lens The optic nerve (Figure 1.19) is formed by the axons and a loss of deformability. This results in a loss of arising from the retinal ganglion cell layer, which form WEBC01NEW 09/16/2016 10:13:0 Page 13 Anatomy 13 Figure 1.17 The anatomy of the lens. Figure 1.18 Remarkable regularity of rabbit lens fibre packing, shown by surface electron microscopy. (Source: Kuzak, J.R., Zoltolski, R.K. & Sivertson, C. Exp Eye Res 2004; 78: 673–687. Reproduced with permission from Elsevier.) the nerve fibre layer of the retina. There are approxi- mater, continuous with that surrounding the brain. mately 1 million nerve fibres in the optic nerve. It is bathed in cerebrospinal fluid (CSF). It passes out of the eye through the cribriform plate The central retinal artery and vein enter the eye in of the sclera, a sieve-like structure. the centre of the optic nerve. In the orbit, the optic nerve is surrounded by a The extraocular nerve fibres are myelinated; those sheath formed by the dura, arachnoid and pia within the eye are not. Figure 1.19 The struc­ ture of the optic nerve. WEBC01NEW 09/16/2016 10:13:2 Page 14 14 Anatomy The ocular blood supply The third, fourth and sixth The eye receives its blood supply from the ophthalmic cranial nerves artery (a branch of the internal carotid artery) via the The structures supplied by each of these nerves are retinal artery, ciliary arteries and muscular arteries shown in Table 1.1. (Figure 1.20). The conjunctival circulation anastomo­ ses anteriorly with branches from the external carotid artery. Table 1.1 The muscles and tissues supplied The anterior optic nerve is supplied by branches by the third, fourth and sixth cranial nerves. from the ciliary arteries. The inner retina is sup­ plied by arterioles branching from the central reti­ Fourth Sixth Third (oculomotor) (trochlear) (abducens) nal artery. These arterioles each supply an area of retina, with little overlap. Obstruction results in Medial rectus Superior Lateral ischaemia of most of the area supplied by that oblique rectus arteriole. The fovea is so thin that it requires no Inferior rectus supply from the retinal circulation. It is supplied Superior rectus (innervated indirectly, as are the outer layers of the retina, by by the contralateral diffusion of oxygen and metabolites across the nucleus) retinal pigment epithelium from the choroidal Inferior oblique capillaries. The endothelial cells of the retinal capillaries are Levator palpebrae (both joined by tight junctions so that the vessels are levators are innervated by a single midline nucleus) impermeable to proteins. This forms an inner blood–retinal barrier, with properties similar to Preganglionic parasympathetic fibres those of the blood–brain barrier. The capillaries from the Edinger of the choroid, however, are fenestrated and leaky. Westphäl nucleus run in The retinal pigment epithelial cells are also joined the third nerve and end by tight junctions and present an external blood– in the ciliary ganglion. retinal barrier between the leaky choroid and the Here postganglionic retina. fibres arise and pass in Breakdown of these barriers is responsible the short ciliary nerves to the sphincter pupillae for the clinical features of many retinal vascular and the ciliary muscle diseases. Figure 1.20 Diagram­ matic representation of the ocular blood supply. WEBC01NEW 09/16/2016 10:13:2 Page 15 Anatomy 15 Central origin with other neurological problems reflecting the accompanying brainstem injury. For example, if the The nuclei of the third (oculomotor) and fourth third nerve fascicles are damaged as they pass through (trochlear) cranial nerves lie in the midbrain; the sixth the red nucleus, the ipsilateral third nerve palsy will be nerve (abducens) nuclei lie in the pons. Figure 1.21 accompanied by a contralateral tremor. Also, a shows some of the important relations of these nuclei nuclear third nerve lesion results in an ipsilateral palsy and their fascicles. of the muscles supplied by the third nerve, bilateral Nuclear and fascicular palsies of these nerves ptosis and a palsy of the contralateral superior rectus, are unusual. If they do occur, they are associated Figure 1.21 Diagrams to show the nuclei and initial course of the (a) third, (b) fourth and (c) sixth cranial nerves. WEBC01NEW 09/16/2016 10:13:4 Page 16 16 Anatomy Figure 1.22 The intra­ cranial course of the third, fourth and sixth cranial nerves. since both sets of crossing fibres from the subnucleus This long course is important because the nerve can be are affected. involved in numerous intracranial pathologies, includ­ ing base of skull fractures, invasion by nasopharyngeal Peripheral course tumours and raised intracranial pressure. Figure 1.22 shows the intracranial course of the third, fourth and sixth cranial nerves. The seventh cranial nerve The seventh cranial nerve arises a nucleus in the pons, Third nerve loops over that of the sixth cranial nerve (Figure 1.21c) and leaves the brainstem at the cerebellopontine angle The third nerve leaves the midbrain ventrally between where it is joined by the nervus intermedius. The two the cerebral peduncles. It then passes between the nerves travel together in the internal auditory canal posterior cerebral and superior cerebellar arteries and where they fuse to form the geniculate ganglion. From then lateral to the posterior communicating artery. there, the somatic motor fibres issue from the skull Aneurysms of this artery may cause a third nerve through the stylomastoid foramen, to supply the palsy. The nerve enters the cavernous sinus in its muscles of the face and scalp. The nervus intermedius lateral wall and enters the orbit through the superior carries secretomotor fibres to the lacrimal gland via orbital fissure. the nerve of the pterygoid canal, a mixed autonomic nerve which includes sympathetic fibres from the Fourth nerve carotid plexus. The preganglionic, parasympathetic The nerve decussates and leaves the dorsal aspect of fibres synapse with postganglionic fibres in the pter­ the midbrain below the inferior colliculus. It first ygopalatine ganglion and reach the lacrimal gland via curves around the midbrain before passing like the the lacrimal nerve. The nervus intermedius also car­ third nerve between the posterior cerebral and supe­ ries taste fibres and secretomotor fibres to the sub­ rior cerebellar arteries to enter the lateral aspect of the mandibular and sublingual glands, which run in the cavernous sinus inferior to the third nerve. It enters the chorda tympani. orbit via the superior orbital fissure. Sixth nerve Fibres leave from the inferior border of the pons. It has Assessment questions a long intracranial course passing upwards along the True or False pons to angle anteriorly over the petrous bone and into the cavernous sinus, where it lies inferomedial to the 1. The cornea fourth nerve in proximity to the internal carotid artery. a Has an endothelial layer that regenerates readily. It enters the orbit through the superior orbital fissure. b Has an epithelial layer that fails to regenerate. WEBC01NEW 09/16/2016 10:13:5 Page 17 Anatomy 17 c The endothelium actively pumps water from the c In primary open-angle glaucoma, there is a stroma. reduction in the number of cells covering the d Is an important refractive component of the trabecular meshwork. eye. d Fluid passes through the trabecular meshwork to e Has a stroma composed of randomly arranged Schlemm’s canal. collagen fibrils. 8. The optic nerve 2. The retina a Axons leave the eyeball through the cribriform a Is ten layers thick. plate. b Has ganglion cells whose axons form the optic b Is not bathed in CSF until it enters the cranial cavity. nerve. c Anteriorly is supplied by blood from the ciliary c Has three types of rods responsible for colour arteries. vision. d Axons are not myelinated in the retrobulbar part d The neuroretina is firmly attached to the retinal of the nerve. pigment epithelium. e Is formed by axons of the nerve fibre layer of the e The RPE delivers vitamin A for rhodopsin retina. production. 9. The third, fourth and sixth cranial nerves 3. The lens a All originate in the midbrain. b A nuclear third nerve palsy will cause a contra­ a Grows throughout life. lateral palsy of the superior rectus. b Is surrounded by a collagenous capsule. c The fourth nerve supplies the lateral rectus. c Cortex and nucleus are rich in organelles. d The sixth nerve has a long intracranial course. d Has a high refractive index owing to its protein e The third nerve may be affected by aneurysms of content. the posterior communicating artery. e Shape becomes more curved during accommo­ dation for near. 4. The suspensory ligament of the lens (the zonule) a Attaches the lens to the ciliary body. Answers b Is part of the iridocorneal angle. 1. The cornea c Is composed of smooth muscle. a False. The human endothelium does not regen­ d Transmits changes in tension to the lens capsule. erate; dead cells are replaced by the spreading of surviving cells. 5. The posterior chamber b False. The epithelial layer readily regenerates. a Is another name for the vitreous body. c True. The endothelial cells pump out ions and the b Lies between the iris, lens and ciliary body. water follows osmotically. Removal of water c Contains aqueous humour, secreted by the ciliary maintains corneal transparency. processes. d True. The cornea is a more powerful refractive d Is in communication with the anterior chamber. element than the natural lens of the eye. e False. The fine, equally spaced, stromal collagen 6. The tear film fibrils are arranged in parallel and packed in an a Is 100 μm thick. orderly manner. This is a requirement for b Tears are drained by the nasolacrimal system. transparency. c The mucoaqueous layer is in contact with the cornea. 2. The retina d Is important in the refraction of light entering the a True. See Figure 1.13. eye. b True. The retinal ganglion cell axons form the e Contains lysozyme and secretory IgA. retinal nerve fibre layer and exit the eye at the optic nerve head. 7. The iridocorneal angle c False. The rods are responsible for night vision a Is the site of aqueous production. and three cone types are responsible for daylight b Lies between the cornea and the ciliary body. and colour vision. WEBC01NEW 09/16/2016 10:13:5 Page 18 18 Anatomy d False. The attachment is loose; the neuroretina c True. The mucin layer is produced by goblet cells. separates from the RPE in retinal detachment. d True. It provides a smooth interface for the refrac­ e True. Vitamin A is delivered by the RPE to the tion of light. photoreceptors and combined with opsin. e True. These account for the antibacterial proper­ ties of the tear film. 3. The lens a True. It does grow throughout life. 7. The iridocorneal angle b True. This is of great importance in cataract surgery. a False. It is the site of aqueous drainage. c False. The older, deep cortical and nuclear fibres b True. See Figure 1.15. lose their nuclei and other organelles. c True. This may reduce aqueous drainage. d True. The high protein content accounts for its d True. Flow depends on the pressure gradient high refractive index. between the anterior chamber and Schlemm’s e True. See page 11. canal and there is also an active component. 4. The suspensory ligament of the lens (the zonule) 8. The optic nerve a True. Zonular fibres extend from the pars plicata a True. This sieve-like structure provides support of the ciliary body to the lens equator. for the optic nerve as it leaves the eye. b False. The zonule lies behind the iris and irido­ b False. In the orbit, outside its pial sheath, the corneal angle. optic nerve is surrounded by cerebrospinal c False. The ciliary muscle contains smooth fluid within the subarachnoid space. This is muscle, not the zonule, which is acellular. in continuity with that in the intracranial d True. Contraction of the ciliary muscle relaxes the cavity. zonular fibres allowing the lens to increase its c True. The supply to the anterior part of the optic curvature and thus its refractive power (this is nerve differs from the supply to the anterior layers ‘accommodation’). of the retina. d True. This is a most important blood supply for 5. The posterior chamber the anterior optic nerve. a False. The vitreous body is quite separate. e False. They are usually not myelinated within the b True. See Figure 1.4. eye. c True. See page 10. f True. It is made up from retinal ganglion cell d True. Communication is via the pupil, in the gap axons. between iris and lens at the pupil margin. If this gap is narrowed or closed, pressure in the poste­ 9. The third, fourth and sixth cranial nerves rior chamber pushes the iris forward and may a False. The nuclei of the sixth and seventh nerves close the angle (acute closed-angle glaucoma). lie in the pons. b True. The superior rectus is innervated by the 6. The tear film contralateral nucleus. a False. The tear film is about 3 μm thick. c False. It supplies the superior oblique. b True. There is a punctum on the medial aspect of d True. This makes the sixth nerve susceptible to both upper and lower eyelids. These allow tears to trauma, which may cause lateral rectus palsy. drain into the nasolacrimal drainage system. e True. It passes lateral to the artery. WEBC02 09/16/2016 11:46:34 Page 19 2 History, symptoms and examination Learning objectives To be able to: ✓ Take and understand an ophthalmic history. ✓ Formulate differential diagnoses for the presenting symptoms of a red eye, sudden and acute loss of vision, ocular pain and diplopia. ✓ Examine the function of the eye (acuity and visual field). ✓ Test pupillary reactions. ✓ Examine eye movements. ✓ Examine the structure of the eye. ✓ Understand the use of fluorescein. ✓ Use the ophthalmoscope. Introduction General ophthalmic Ophthalmic diagnosis is heavily dependent on a good history history and a thorough examination. The majority of A good history must include details of: ophthalmic diagnoses do not require additional tests. The sequence of history and examination is described Ocular discomfort or symptoms of visual loss, with below. time of onset, eye affected and associated non- It is imperative that hands are washed before and ocular symptoms (Table 2.1). after each examination. If ocular infection is sus­ Past ocular history (e.g. poor vision in one eye since pected, then it is necessary to disinfect the slit lamp birth, recurrence of previous disease, particularly and other handheld equipment. Equipment making inflammatory). contact with the eye, for example a diagnostic contact Past medical history (e.g. of hypertension, which lens, is either disposable or routinely disinfected. may be associated with some vascular eye diseases such as central retinal vein occlusion, diabetes, which may cause retinopathy, and systemic inflam­ Ophthalmology Lecture Notes, Twelfth Edition. matory disease such as sarcoidosis, which may Bruce James, Anthony Bron and Manoj V. Parulekar. cause ocular inflammation). © 2017 Bruce James, Anthony Bron and Manoj V. Parulekar. Published 2017 by John Wiley & Sons, Ltd. Drug history, since some drugs such as isoniazid Companion Website: www.lecturenoteseries.com/ophthalmology and chloroquine may be toxic to the eye. WEBC02 09/16/2016 11:46:34 Page 20 20 History, symptoms and examination Table 2.1 Key points in the ophthalmic history. Table 2.2 Red eye: causes and symptoms. Consider the symptoms carefully: Major causes Trauma How long have they been present? Infection Are they continuous or intermittent? Acute glaucoma What precipitated them? Other forms of inflammation What makes them better or worse? Associated Discharge How are they changing? symptoms Pain Are there associated symptoms? Is there a history of previous eye, or relevant Photophobia systemic, disease? Blurred vision Is there a relevant drug history, family history or social history? (alcohol, smoking, exposure to chemicals) the white of the eye, that is the exposed bulbar Family history (e.g. of ocular diseases known to be conjunctiva and underlying sclera. It may also involve inherited, such as retinitis pigmentosa, or of disease the lid margins, and further examination may reveal where family history may be a risk factor, such as redness of the tarsal conjunctiva. Redness implies glaucoma). vessel dilatation, often inflammatory but sometimes Presence of allergies. due to congestion alone. It can accompany infection, inflammation, trauma and acute elevation of intra­ ocular pressure and also obstruction to the venous Specific ophthalmic drainage of the eye (Table 2.2). Determining associ­ ated symptoms will help establish the diagnosis history (Table 2.3). The term ‘conjunctival injection’ is also used to describe redness or inflammation of the globe The symptoms associated with specific eye diseases (Figure 2.1a). are brought together here to provide an overview of the important questions to ask. A more detailed Trauma description of each disorder is given in later chapters and you should review this section when you have A traumatic cause is usually obvious and you should read more about the specific conditions. note the precise details of the event. Was it due to a blunt injury to the eye, a sharp object or a high-speed projectile? High-speed metal fragments, thrown off Red eye during hammering, may penetrate the globe and A red eye is one of the most common presenting threaten sight. The patients may be entirely unaware complaints in ophthalmology. It means redness of that their red eye is due to an ocular injury. Figure 2.1 (a) Injected bulbar conjunctiva associated with a corneal ulcer. (b) A subconjunctival haemorrhage. WEBC02 09/16/2016 11:46:35 Page 21 History, symptoms and examination 21 sign is often in the meridian of the lesion, aiding its Table 2.3 Red eye: differential diagnosis. detection, or it may surround the limbus when Deep red, sclera Subconjunctival haemorrhage trauma is associated with iritis. Trauma can also obscured cause conjunctival injection (vessel dilation). Diffuse bulbar and Infective conjunctivitis Chemical injury may be associated with generalized tarsal injection Allergic conjunctivitis or local conjunctival inflammation, but alkali burns may cause ischaemic whitening, signifying severe Angle closure glaucoma tissue damage. Reaction to topical medication Dry eyes Infection In association with orbital cellulitis The commonest site of infection is the conjunctiva Diffuse/focal bulbar Episcleritis itself. injection Scleritis Conjunctivitis is a generalized inflammation of the Chemical injury conjunctiva and therefore associated with redness Endophthalmitis of both the bulbar and the tarsal conjunctiva. Pingueculae There are symptoms of discharge and mild dis­ comfort rather than pain. Any visual blur due to Pterygia discharge is cleared on blinking. Bacterial infec­ Eyelid malposition tions are associated with a purulent discharge that Blepharitis may stick the lids together. Viral infections cause a Cavernous sinus thrombosis more watery discharge. In severe cases, where the cornea is affected in addition to the conjunctiva Perilimbal (ciliary) Iritis (e.g. in adenovirus keratoconjunctivitis), the injection Keratitis patient experiences pain, photophobia and blur­ Corneal abrasion red vision. Chlamydial infections can produce a Corneal ulcer chronically red eye. Corneal infection may be peripheral or central. A Corneal foreign body peripheral lesion does not affect vision but may be heralded by a tell-tale ciliary flush. A central Here are some causes of a red eye due to trauma: lesion affecting the visual axis is more often A subconjunctival haemorrhage (Figure 2.1b) is bright accompanied by a circumcorneal flush which red due to exposure of the blood to ambient oxygen becomes more generalized with increased sever­ which has diffused through the conjunctiva. It ity of the infection. The eye is painful and the obscures the white of the sclera and therefore, if vision reduced. There may be a mucopurulent traumatic, may hide the site of an entry wound. The discharge. A history of contact lens use is common cause of a spontaneous subconjunctival haemor­ as an initiating factor. rhages may not be found, but it can be caused by Intraocular infection (endophthalmitis) may occasion­ systemic hypertension or blood clotting disorders ally occur within days following intraocular surgery. It including anticoagulant therapy. The international causes a marked generalized increasing conjunctival normalized ratio (INR), a measure of the prothrombin inflammation. The eye is painful (unusual after rou­ time, may need checking. tine intraocular surgery) and the vision reduced. A Corneal injury. The sensory innervation of the cor­ history of recent surgery is the clue. Such a patient nea is chiefly nociceptive, and its innervation den­ requires immediate referral to an eye unit. sity is higher than in any other part of the body, for An infection of the orbit, orbital cellulitis, presents example 400 times greater than in the fingertip. Any with swollen and often erythematous lids. The injury or inflammation of the cornea therefore globe is pushed forward (proptosed), the conjunc­ causes extreme pain and watering of the eye (epi­ tiva is oedematous (chemotic) and the eye is phora). Corneal foreign bodies and abrasions are diffusely red, due to both conjunctival and epis­ typical examples of such injuries. They stimulate cleral vessels dilatation. Eye movements are reflex antidromic vasodilatation of limbal episcleral reduced. This is a medical emergency, since vision vessels, resulting in a patch of redness at the limbus, may be lost rapidly and permanently, due to optic termed a limbal or ciliary flush. This characteristic nerve damage. WEBC02 09/16/2016 11:46:35 Page 22 22 History, symptoms and examination form of allergic eye disease, will also present as a red, itching, irritable eye and vision may be affected. The upper tarsal plate may exhibit typical broad elevations called ‘cobblestone’ papillae, rich in eosi­ nophils and other inflammatory cells. There may be a history of atopy. With both, there may be a mucus discharge (Figure 2.2). In episcleritis the episcleral tissues are inflamed. This may result in focal or diffuse inflammation, and may or may not be painful. There is no dis­ charge, and the vision is not reduced. In scleritis, inflammation of the sclera is associated Figure 2.2 The appearance of giant (cobblestone) with the collagen vascular diseases. Focal or gener­ papillae in vernal keratoconjunctivitis. alized inflammation and swelling of the sclera is seen through the conjunctiva, which is also swollen. Pain is deep and boring. Acute glaucoma In iritis, an inflammation of the iris, there is circum­ limbal injection. The sudden rise in pressure associated with acute angle closure glaucoma, and other causes of acute glaucoma, result in a generalized red eye, corneal Miscellaneous causes of a red eye clouding, reduced vision and severe pain. It needs Dry eyes may also be associated with mild redness, urgent treatment (Chapter 10). irritation and ‘tiredness’ of the eye. In severe cases the vision may be blurred. Other