Normal Corneal re \202ection shows correct alignment. Neither eye moves as they are altern ately covered. Left convergent squint Corneal re \202ection shows malalignment. As the right eye is cover ed the left moves out to take up \201xation. Left divergent squint Corneal re \202ection shows malalignment. As right eye is covered th e left moves in to take up \201xation. Fig 2. The cover test relies on the ability to \201 xate. If there is eccentric \201 xa tion (ie foveal vision is so poor that it is not used for \201 xation), the deviating eye will not move to take up \201 xation. Corneal re \202 ection shows that malalignment is present. 3 The primary muscle moving an eye in a given direction is the agonist. A muscle in that ey e that moves it in the same direction as the agonist is a synergist \200\224eg in abducting the left eye, the left lateral rectus is the agonist, the left superior and inferior obliq ues are synergists; the left medial, superior, and inferior recti are antagonists.39 Superi or & inferior obliques are the primary muscles of torsion. Pupils Pupil inequality Light detection by the retina is passed to the brain via the optic nerve (aff erent pathway) and pupil constriction is mediated by the oc- ulomotor (third) cr anial nerve (eff erent pathway). The sympathetic nervous system is responsible for pupil di latation via the ciliary nerves. Aff erent defects (absent direct response) The pupil won \200\231t respond to light, but constricts to a beam in the other eye (consensual response) . Constriction to accommodation still occurs. Causes: optic neuritis, optic atrophy, retina l disease. The pupils are the same size (consensual response unaff ected). Mar- cus Gunn sw inging \202 ashlight test: On beaming light to the normal eye, both pupils constrict (dir ect & consensual reaction); if, on swinging the light to the aff ected eye, the pupil dilat es it is a Marcus Gunn pupil. Eff erent defects The 3rd nerve also mediates eye movement an d eyelid re- traction. With complete palsy there is complete ptosis, a \201 xed dilated p upil, and the eye looks down (superior oblique still acts) and out (lateral rectus act- ing ). Causes: cavernous sinus lesions, superior orbital \201 ssure syndrome, dia- betes, pos terior communicating artery aneurysm. The pupil is often spared in vascular causes (diabete s; hypertension). Pupillary \201 bres run in the periphery, and are \201 rst to be invo lved in compressive lesions by tumor or aneurysm. Other causes of a \201 xed dilated pupi l Mydriatics, trauma (blow to iris), acute glaucoma, coning ie uncal herniation (OHCM p840) . Holmes \200\223Adie pupil Initially monolateral, then bilateral, pupil dilatation with de layed responses to near vision eff ort, with delayed redilation. Typical pa- tient: A young woman, with sudden blurring of near vision, and a dilated pupil, with slow responses to ac commodation, and, especially, to light (looks unreac- tive, unless an intense light is used for >15min), ie a tonic pupil. Slit lamp exam: Iris shows spontaneous wormy movements (iri s streaming). Holmes \200\223Adie syndrome: Tonic pupil, absent knee/ankle jerks and BP \200\201.1 The pupil \200\231s size may \202 uctuate, and get smaller than the other (if both pupils are involved they may be confused with Argyll Robertson pupils). See below for other tonic pupils.2 Horner \200\231s syndrome occurs on disrupting sympa- thetic \201 br es, so the pupil is miotic (smaller), and there is partial ptosis, and the pupil does not d ilate in the dark. Unilateral facial anhydrosis (sweating \200\201) may indicate a lesion p roximal to the carotid plex- us \200\224if distal, the sudomotor (sudor = sweat) \201 bre s will have separated, so sweating is intact. Congeni- tal Horners: iris heterochromia (see \201 g 1). Argyll Robertson pupil occurs in neurosyphilis is bilateral miosis, pupil and diabetes; there irregularity, and no response to light, but there is response to accommoda tion (the prostitute \200\231s pupil accommodates but does not react). The iris is spongy, the pupils dilate poorly, and there may be ptosis. Causes of light-near dissociation (LND, \200\223ve to light +ve to accommodation): Argyll Robertson pupil; Holmes \200\223Adie and Parinaud syndromes;3 meningitis; alcoholism; tectal lesions, eg pinealoma; mesencephalic o r thalamic lesions.4 424 \200 y g o o m a h t h p O l l Causes of Horner \200\231s \200 Posterior inferior cer- ebellar artery or basilar artery occlusion \200 Multiple sclerosis \200 Cavernous sinus thrombosis Pancoast \200\231s tumor \200 Hypothalamic lesions \200 Cervical adenopathy \200 Medi astinal masses \200 Pontine syringomyelia \200 Klumpke \200\231s palsy, p766 \200 Aor tic aneurysm 1 Selective impairment of monosynaptic connections of 1a aff erents \200\200presynaptic inhibition on aff erent 1a input to ventral horn motor neurons 40 \200\230 absent deep re \202 exes persist despite cord pathology. 41 There is auto- nomic dysfunction too with di sturbed vasomotor and sweating functions \200\224and cough. 42 2 Migraine; syphilis; diabet es; chickenpox; arteritis; sarcoid; myasthenia; hamartoma; anti-Hu autoantibod- ies to neur al nuclei; Sj gren \200\231s; Meige \200\231s syndrome; botulism; dermatomyositis; amyloid osis; paraneoplasia. 3 LND + nystagmus, upward gaze palsy and eyelid retraction (Collier \200\231s sign). 4 The path from the optic tract to the Edinger \200\223Westphal nucleus is disrupted but deeper cortical connec- tions remain intact, so accommodation is spared. 425 Irises What color are your eyes? y g o o m l a h t h p O l Fig 1. Heterochromia (sectoral above, central below). Both may be a normal variant; secto- ral heterochromia may be a feature of Waardenburg syndrome (WS, p548). Type 1 WS is an auto somal dominant disorder whose other signs are hearing loss, pigmental abnormalities of the hair and skin, and dystopia canthorum (wide nasal bridge due to sideways displace- ment of the inner angles of the eyes). NB: the top image also displays iris hypoplasia, further des cribed in Fig 2. Courtesy of Jon Miles. Fig 2. Iris hypoplasia. There are \201 bre separations in the stroma. It is associated wi th Wilms \200\231 tumor, cerebral gigantism, congenital rubella, and other rare syndromes. In developmen- tal glaucomas (eg Reiger syndrome) there is anterior segment dysgenesis. Refraction Refractive errors arise from disorders of the size and shape of the eye. Correct refraction depends upon the distance between the cornea and the retina, and the curvatures of the lens and cornea (see \201 g 1). Myopia (short sight) The eyeball is too long. In any eye, the nearer objects come to the eye, the further back their image falls. With myopi a, only close objects focus on the retina (short sightedness) unless concave spectacle (or contact) lenses are used. Causes: Genetic (chromosome 18P & 12Q). 43 Very close work in the early decades (not just at school) may lead to changes in the syn- thesis of mRNA and the concentration of matrix metalloproteinase, resulting in myopia. Acetylcholine, dopamine, an d glucagon are triggers for eye growth. 44 426 In normal growth, changes in eyeball and lens curvature compensate for the eye getting long er as it grows, but in myopic children, such compensations may not be occurring, so myopia worsens with age. Most do not become myopic until the age of 6yrs (a few are born myopic). Myopia will then usually continue to worsen until the late teens, when changes stop below 6 dioptres in most people. It is important, therefore, for children with myopia to have the ir eyes regularly checked, as spectacle changes are to be expected, perhaps every 6 months. Avoid over-correction as this can make myopia worse. 45 In later life, increasing myopia m ay indicate developing cataracts. y g o o m a h t h p O l l NB: when aboriginal people are exposed to western education, rates of myopia rise from 0 t o Western levels (eg 50%) and there appears to be a dose-response curve relating hours spen t indoors to degree of myopia. But before we all instantly put down this book and go out to play, remember that this relationship has only been proven in children. 45 Pathological my opia: Rarely ( \211 3%), myopia progresses above 6 dioptres (sometimes up to >20 dioptres). This has serious consequences later in life be- cause secondary degeneration of the vitreo us and retina can lead to retinal detachment, choroidoretinal atrophy and macular bleeding. Management: Spectacles, contact lenses, or LASIK, p464. Bifocals prevent retinal blur if k nown accommodative lag. 46,47 Astigmatism This is present if cornea or lens don \200\231t h ave the same degree of curvature in horizontal and vertical planes, so that the image of ob jects is distorted either longitudinally or vertically. Correcting lenses compensate ac- co rdingly. It can occur alone, or with myopia or hypermetropia. Hypermetropia (long sight) Th e eye is too short. Distant objects, when the eye is at rest, are focused behind the retina . The ciliary muscles contract, and the lens gets more convex to focus the object on the re tina. This can produce tiredness of gaze, and sometimes, convergent squint in children. It is correct- ed by convex lenses to bring the image forward to focus on the retina. Presbyop ia The ciliary muscle reduces tension in the lens, allowing it to get more convex, for clos e focusing. Young lenses can go from far to near in 0.4sec (approaching kisses go out of fo cus at 7cm). With age, the lens stiff ens and (presbyopia), hence the need for glasses for reading (but which do not make that approaching kiss any easier either in its appreciation or execution). \201\2011 These changes start in the lens at 40yrs and are complete by 60. \201\201Marcel Proust, on the brink of carnal knowledge, \201 nds the limit of accommoda tion: \200\230In this brief passage of my lips towards her cheek it was ten Albertines I saw; th is single girl being like a goddess with several heads, that which I had last seen \200 gav e place to another. At least \200 a faint perfume reached me from it. But alas \200\224for in this matter of kissing our nostrils and eyes are as ill placed as our lips are shaped \200\224suddenly my eyes ceased to see; next, my nose, crushed by the collision, no longer perceived any fragrance, and without thereby gaining any clearer idea of the taste of the r ose of my desire, I learned, from these unpleasant signs, that at last I was in the act of kissing Albertine \200\231s cheek. \200\23149 427 Normal eye Normal eye Myopia Hypermetropia y g o o m l a h t h p O l Light focused behind the retina Light focused in front of the retina Corrected with concave lens Corrected with convex lens Fig 1. Myopia and hypermetropia. Visual \201 eld defects When assessing for visual \201 eld defects establish 4 facts: 1 Is the defect bilat- eral? 2 Does the defect have sharp boundaries? 3 Do defects lie in th e vertical or horizontal meridians? 4 What is the acuity? Lesions of sudden onset are often due to vascular causes ( \201 g 1). \200\207Because of CNS plasticity, people often thin k that the area of the defect (scotoma) is smaller than it is. 49 428 \200 Retinal lesions cause defects in one eye only. Lesions involving the retinal nerve \201 b res give defects with boundaries in the horizontal meridian. Optic nerve lesions giving \201 eld defects are typically central, asymmetrical, and unilateral \200\224and acuity is often aff ected. When lesions are behind the optic chiasm \201 eld defects are bilateral, acuity tends not to be impaired (but objects in the aff ected \201 eld cannot be seen) a nd boundaries are in the vertical meridian. Tests Finger confrontation: The patient closes one eye, \201 xes on your eye and notes the presence of a \201 nger in all \201 elds mapped, against your vision. It is used for testing peripheral \201 elds. Hat-pin confron tation: The patient \201 xes on your eye (sit 1 meter away). Red (central vision) or wh ite (peripheral vision) hat-pins are used to de \201 ne any vertical meridian, the size of the blindspot and the boundaries of any scotomas. If a scotoma is \200\230absolute \200 \231, the hat-pin disap- pears completely. If it is \200\230relative \200\231, the hat-pin only dulls as it moves across the \201 eld of the scotoma, as opposed to being bright in the unaff ected \201 eld. y g o o m a h t h p O l l Optic chiasmal lesions may show a phenomenon whereby if 2 identical colored objects are sho wn to one eye in the two vertical halves of the visual \201 eld (eg the right) one appear s to be brighter and sharper than the other (if right eye, the left hemi \201 eld is brigh ter than the right). Computerized visual \201 eld analysers give accurate assessments of such visual \201 elds. Amsler grids detect distortion in central vision, eg from macular disease. The chart is 10 \211\210 10cm square with 5mm squares drawn on it and a dot in the center. With the chart held at 30cm the patient is instructed to look at the dot and report any distorted squares or wavy lines (metamorphopsia). Diagnosing the lesion \200\231s site Superior parts of the visual \201 eld fall inferi- orly on the retina, temporal \201 elds on the nasal retina and vise versa. Fibers from the nasal retina of both eyes cross in the optic chiasm to joi n uncrossed temporal retinal \201 bres. A pituitary tumor may disrupt the chiasm, aff ect - ing \201 bres crossing from nasal retinas, so causing bitemporal \201 eld defects. If it grows more to one side than the other, it can superimpose a central optic nerve defect as well. As \201 bres cross they maintain position (superior \201 bres stay superior). From the optic chiasma \201 bres pass in the optic tract to the lat- eral geniculate body , then as the optic radiation to the visual cortex. A contralateral upper homonymous quadrantanopia may be caused by temporal lobe tumors. Post erior visual cortex lesions cause non-peripheral homonymous hemianopic scotomas (anterior v isual cortex deals with peripheral vision) \200\224with macular sparing, if the cause is po sterior cerebral artery ischaemia (central areas have overlap \202 ow via the middle cere bral artery, which is why acuity may be preserved). MRI is the best aid to diagnosis. Cause s of visual cortex \201 eld defects: \200 Ischaemia (TIA, migraine, stroke) \200 Glio ma \200 Meningioma \200 Abscess \200 AV malformation \200 Drugs, eg ciclosporin. 50 NB: cortical visual defects may be fundamentally capricious \200\224in that when an object is presented to the aff ected \201 eld of view, the patient announces that he cannot see it \200\224yet \200\230guesses \200\231 correctly that it is there (non-cortical visual p athways): there are some things we know we can see; other things we see without knowing (bl indsight1) and others that we know without seeing (for example that a table has 4 legs when we can only see 3 at any one time). 1 Blindsight lesion patients respond to visual fear signals independently from conscious ex perience \200\224ie these signals reach the amygdala bypassing the visual cortex.51 429 y g o o m l a h t h p O l Fig 1. Scotomata \201\201Confrontation depends on mutual \201 xation, and it is necessary to con- centrate hard to work out what is going on, but, for one second, allow yourself to re \202 ect on what your patient will be thinking and feeling, most eloquently expressed by John D onne on accomplishing this maneuver: I \201 x mine eye on thine, and there Pity my pictur e burning in thine eye \200 Towards the end of your professional life you will have engage d in mutual \201 xation many, many times, and as you continue to do so, ask yourself if t hese images of suff ering are falling on your retina like so many layers of snow on a barre n land, or whether, just sometimes, you might allow your eye to thaw and resolve itself int o perhaps just one true tear. The red eye Red eyes are commonly also painful. Some causes are dangerous to vision and req uire specialist supervision (acute glaucoma, acute iritis, corneal ul- cers); others are mo re easily treated (episcleritis, conjunctivitis [see \201 g 4], spontaneous conjunctival hemorrhage). Carefully examine all red eyes to assess acuity, cornea (use \202 uorescein drops p432), and pupillary re \202 exes. Acute closed angle glaucoma ( \201 gs 1 & 3) A d isease of middle years (commoner in Asia). In 25%, acute uniocular attacks occur with head- ache, nausea and a painful red eye, 52 often pre- ceded by blurred vision or haloes around lights, at night. Cause: Blocked \202 ow of aque- ous from the anterior chamber via the canal of Schlemm. Pupil dilatation at night worsens this. Intraocular pressure (IOP) then r ises to \200\20630mmHg (normal 15 \200\22320), the pupil becomes \201 xed and dilated an d axonal death occurs. IOP \200\200 may make the eye feel hard. A shallow anterior chamber (pre dis posing factor) may be seen in the other eye (shine a torch from the side, half the iris lies in shadow). \200 Send to eye unit now for gonioscopy.1 \201\227: Pil- ocarpine 2 \200\2234% drops/2h (miosis opens a blocked, \200\230closed \200\231 drainage angle, \201 g 2) + 500mg IV acet a z- olamide stat then 250mg/ 8h PO/IV (it \200\201 aqueous form ation). Analgesia and antiemetics may be used. Admit to monitor IOP. \200 Mannitol 20% IVI may be needed ( \211 500mL). Topical steroids and antihypertensive drops ( \200 -blockers, prostaglandin analogs, \200 -adrenergic ago- nists) are used. Peripheral iridectomy (lase r or surgery) is done once IOP is con- trolled (rarely as an emergency if IOP uncontrollabl e). A piece of iris is removed (at \200\23012 o \200\231clock \200\231) in both eyes to al low aqueous to \202 ow. Anterior uveitis/iritis The uvea is the pigmented part of the eye (iris, ciliary body, choroid). The iris and ciliary body are called the anterior uvea; as iris in \202 ammation will involve the ciliary body, the best term is anterior uveitis, bu t note that anterior and posterior compo- nents may be aff ected together. The patient: Acu te pain, photophobia, \200\201acuity ( \200\223 aqueous precipitates), lacrimation (no sti cky discharge, unlike in conjunctivi- tis), circumcorneal redness (ciliary congestion), sma ll pupil, initially from iris spasm; later it may be irregular or dilate irregularly due to adhesions between lens and iris (synechiae). Talbot \200\231s test is +ve:4 Slit lamp: Whi te precipitates on the back of the cornea; anterior cham- ber cells (pus = \200\230hypopyon \200\231). It typically aff ects those of working age. Causes: see MINIBOX; often none is found ( \200\230 \200\230autoimmune \200\231). It may relapse so regular eye clinic care a nd follow-up is vital. \201\227: Aim to prevent damage from prolonged in \202 amma- tion (disrupts \202 ow of aqueous ( \200\203glaucoma adhesions between iris & lens). Drops: 0.5 \200\2231% prednisolone/2h, to \200\201 in \202 ammation (hence pain, redness, and e xudate). To prevent adhesions between lens and iris (synechiae) keep pupil dilated with cyc lo- pentolate 0.5%/8h, unless very mild. Use the slit lamp to monitor in \202 ammation. In travitreal and biological agents show promise eg anti-TNF and anti-CD20 if HLAB27+ve (most with anterior uveitis are).55 Adalimumab has a role.56 430 \200 Fig 1. Acute closed angle glaucoma. Courtesy of Prof J Trobe. y g o o m a h t h p O Trabecular meshwork obstructed l Canal of Schlemm l Trabecular meshwork Iris Cornea Iris pressing forward Obstructed circulation of aqueous humor Fig 2. Acute closed angle glaucoma. Lens Lens Types & causes of uveitis Anterior uveitis: 53,54 \200 Ank. spond.;Still \200\231s2, p654 \200 Sarcoid; Beh et \200\231s, etc3 \200 Crohn \200\231s/UC; Reiter \200\231s \202 \223 \200 Herpes, TB, syphilis, HIV Intermediate uveitis: \200 MS; lymphoma; sarcoid Po sterior & panuveitis: \200 Herpes simplex + zoster toxoplasmosis; TB; CMV; endophthalmiti s Lymphoma; sarcoidosis \200 Beh et \200\231s 431 y g o o m l a h t h p O l Fig 3. Acute closed-angle glaucoma (engorged vessels, haze, oval pupil. Bristol Eye Hospi tal. Fig 4. Giant papillary conjunctivitis. Bristol Eye Hospital. Identifying dangerous red eyes: answer these questions: 1 Is acuity aff ected? A quick but sensitive test is the ability to read news- print with refractive errors corrected with gla sses or a pin-hole. Reduced acuity suggests dangerous pathology. 2 Is the globe painful? Pain is potentially sinister, foreign body sensation may be so, irritation rarely is. 3 Does the pupil respond to light? Absent or sluggish response is sinister. 4 Is the cornea intact? Use \202 uorescein eyedrops, p432. Corneal damage may be due to trauma or ulcers. Ask about trauma and discharge, general health and drugs; remember to check for raised pres sure. \200\207If in doubt, obtain a specialist opinion today. Conjunctivitis Anterior uveitis Acute glaucoma Pain + Photophobia normal Acuity normal C ornea Pupil normal Intraocular pressure normal ++ ++ \200\201 normal small normal ++ to +++ \200\223 \200\201 steamy or hazy large \200\200 1 The Zeiss indirect goniolens employs prisms in the place of mirrors. Its 4 prisms allow v isualization of the iridocorneal angle in 4 quadrants simultaneously; it is used with a sli t lamp. 2 In juvenile arthritis, screen the child every 4 months until they are old enough to report symptoms. 3 This is one of the few occasions when the Sherlock Holmes \200\231s a mong us can properly ask \200\234Have you been handling tarantulas recently? \200\235 (The ir hairs cause uveitis.) 4 Pain increases on convergence (and pupils constrict) as patients watch a \201 nger approach their nose. More red eyes \200\224cornea and conjunctiva Corneal problems Keratitis is corneal in \202 ammation (identi \201 ed by a white area on the cornea \200\224indicating a collection of white cells in corneal tissue). Corneal abrasion is an epithelial breach; it occurs withou t keratitis, eg in trau- ma, when prophylactic antibiotic ointment (eg chloramphenicol) may be used. Ulceration with keratitis is more serious: treat as an emergency, as below. Loss of corneal epithelium causes pain, photophobia \200\201vision. Uninfective corneal ulce rs may result from scratches from sharp objects, trauma, chemical injury or previous cornea l disease. Use \202 uorescein drops and a (blue) bright light (shone tangentially across the globe) to aid diagnosis. Corneal lesions stain green (drops are orange and become more yellow on contact with the eye). Corneal ulcers may be bacterial (beware pseudomonas: may p rogress rapidly), herpetic (simplex; zoster), fungal (candida; aspergillus), protozoal (aca ntham- oeba) or from vasculitis, eg in rheumatoid arthritis. Don \200\231t try treating ulc era- tive keratitis on your own: scarring and visual loss may occur. Except for a simple ab rasion ( \201\227: chloramphenical ointment cyloplegia) get help today for urgent diagno stic smear/Gram stain and scrape. Liaise with microbiologist. \201\227: p433. In early sta ges of ophthalmic shingles, use oral aciclovir (p420). H. sim- plex dendritic ulcers: p416. Cycloplegics (p456) ease photophobia. See BOX. Episcleritis ( \201 g 1) In \202 ammation below the con- junctiva in the episclera is often seen with an in- \202 ammatory nodule. Bilateral in 30%. The sclera may look blue below a focal, cone-shaped wedge (thin end towa rds pupil) of engorged vessels that can be moved over the area, unlike in scleritis, where engorged vessels run deeper. The eye aches dully and is tender (esp. over in \202 amed are a). Acu- ity is usually OK. No cause is found in 70%, 53 but it may complicate rheumatic fe ver, PAN or SLE. \201\227: Topical or systemic NSAIDs. 57,58 Scleritis (Vasculitis of the sclera.) 59 Rarely, the sclera itself is in \202 amed and pain is signi \201 cant. There is generalized in \202 ammation with oedema of the con- junctiva and scleral thinning (if necrotizing, globe perforation is a risk). Associ- ation: connective tissue disorders; infe ctions. Refer to a specialist. Acuity may be \200\201 (esp. if associated with ocular hype rtension, a systemic disease, uveitis, or there is posterior scleritis). Tests: ESR, ANCA f or AAV antineutrophil cytoplasmic antibody-associated vasculitis (Weg- ener \200\231s \202 \223+polyangiitis). Most need oral steroids/immunosuppresion (cipro \202 oxa- cin, topical forti \201 ed amikacin, and vancomycin drops if staphylococcal). 60,61 Conjunctivitis The conjunctiva is red and in \202 amed, and the hyperaemic ves- sels may be moved over the s clera, by gentle pressure on the globe. Acuity, pupillary responses, and corneal lustre are unaff ected. Eyes itch, burn, and lacrimate. There may be photophobia. It is often bilater al with discharge stick- ing lids together. Causes: adenoviruses (small lymphoid aggregates appear as follicles on conjunctiva), bacteria (purulent discharge more prominent), or al- lergic. Chloramphenicol 0.5% drops/4 \200\2236h is often used (or fusidic acid drops). Stap hs are common causes \200\224and resistance to cipro \202 oxacin is spreading, and, to a l esser extent, to gentamicin. 62 It is usually self-limiting (more prolonged if allergic). I n prolonged conjunctivitis, esp. in young adults or those with sexual diseases, consider ch lamydial infection (get expert help; see ophthalmia neo- natorum, p36). \201\227 for aller gic conjunctivitis: Try anti histamine drops, eg emed- astine or olopatadine refer if not s ettling in a few days. Sodium cromoglicate and steroid drops (after advice from an ophthalm ologist) may help. 63 Subconjunctival hemorrhage This harmless but alarming pool of blood b e- hind the conjunctiva is from a small bleed ( \200\234are you on warfarin?etc; your INR i s ? \200\235); check BP. It often occurs in frail old ladies who you can make laugh by as king \200\234have you been white-water rafting recently? \200\235 (leptospira in sewage). 432 \200 y g o o m a h t h p O l l Fig 1. Episcleritis. 433 \200\207Accurate, rapid diagnosis is vital! Managing corneal ulcers Refer to a specialist today. What appears below is so that one can have intelligent conversations with specialist s, and should not be regarded as a blueprint for therapy by the inexperienced. Herpetic ulc ers: see p416. Smears and cultures Liaise with microbiologist. Specialists may take: 1 Smea r for Gram stain \200\224if chronic ulcer Giemsa, PAS (periodic acid Schiff ) for fungi, ZN (Ziehl \200\223Neelsen) or auromine for TB. 2 Conjunctival swab to blood agar for tear \201 lm contaminants. 3 Multiple corneal scrap es (by experienced person) from ulcer edge with needle for direct innoculation and PCR/other molecular methods. y g o o m l a h t h p O 4 Request the cultures detailed below. Acute ulcers: Presume bacterial, so culture with blo od agar (grows most organisms), chocolate agar (for Haemophilus and Neisseria), nutrient br oth (anaerobes), cooked meat broth (aerobes/anaerobes). Chronic history: Con- sider raritie s; culture as above + BHI (brain heart infusion broth for fastidious organisms & fungi, ie kertomycosis), Sabouraud \200\231s plate for fungi, anaerobic blood agar (peptococcus, prop rionobacteria) + thioglycollate (anaerobes). Unusual features: Use also viral transportatio n medium, Lowenstein \200\223Jensen agar slope for TB, E. coli seeded agar for acanthamoeba . PCR for fungi.64 Management: Do smears & culture. Get help. Remove contact lenses. Test c ranial nerve V. Is he/she HIV +ve? Until cultures are known, alternate chlo- ramphenicol dr ops (for Gram +ve bacteria) with o \202 oxacin drops (for Gram \200\223ve bacteria) 65 or 0.3% cefuroxime drops with gentamicin drops. Adapt in the light of cultures.2 Admit, eg if diabetes, immunosuppression, or you doubt that the patient will manage the drops. O \202 oxacin is given up to a drop every 15min to start with, reduced as necessary (most eye depa rtments have their own protocol). Steroid drops can be added once recovery starts. l Fig 2. Anatomy of the eye. 1 Mooren \200\231s ulcer is a chronic, painful peripheral corneal ulcer of unknown cause th at easily leads to loss of vision. Severe pain is common and eye(s) may be very red, photop hobic, and tearing. It is more common in southern and central Africa, China, and India. Tre atments tried: steroidal and non- steroidal anti-in \202 ammatory drops, cytotoxics (topic al and systemic), conjunctivectomy, and cornea debridement (super \201 cial keratectomy). None is known to be superior. 2 In one study, the chief Gram +ve bacteria were coagulase \200\223ve staphs (19%) & corynebacteria (16%). The chief Gram \200\223ve organisms were M oraxella (19%) and Pseudomonas aeruginosa (PA; 3%). PA may be sensitive to ceftazidime and cipro \202 oxacin. Amikacin, imipenem, and gentamicin are 2nd-line.65,67 \202\200 66 Sudden painless loss of vision \200 Urgent help is needed in: retinal artery occlu- sion o f <6h; any sudden visual loss of <6h if the cause is unknown, or giant cell arteritis (GCA) . 5 questions: \200 Headache associated? (GCA, ESR \200\200 ( \200\207do this test urgent ly in all cases \200\20650yrs old) \200 Eye movements hurt? (optic neuritis) \200 Ligh ts/ \202 ashes preceding visual loss? (detached retina) \200 Like a curtain descending? amaurosis fugax may precede permanent visual loss, eg from emboli/GCA) \200 Poorly contr olled DM: \201 g 1 shows vitreous hemorrhage (bottom left) from new vessels (top right). Check: Acuity, pupil reaction, fundi. Then refer. See BOX. Anterior ischaemic optic neuropa thy (AION) The optic nerve is damaged if posterior ciliary arteries are blocked by in \202 ammation or atheroma. Fundosco- py: pale/swollen optic disc. Arteritic AION (giant cell ar teritis): The other eye is at risk until steroids are given. Symptoms: malaise, jaw claudic ation (chew- ing pain) tender scalp and temporal arteries (thickened absent pulses), neck pain. Tests: ESR (>47) & CRP (>2.45mg/dL) preferably before steroids; tem- poral arter y biopsy within 1 week of starting prednisolone; may miss aff ected sections of artery (ski p lesions). \201\227: \200 Start prednisolone 80mg/24h PO prompt- ly (some advocate highe r IV doses if visual failure is occurring). Tailing off ster- oids as ESR and symptoms sett le may take >1yr. 67,68 Nonarteritic AION: Associations: BP \200\200; lipids \200\200; DM, smoking. Treating these protects vision in the other eye. Histology: necrosis & apoptosis a t the photoreceptor level. 69 Vitreous hemorrhage (VH) Source from retinal new vessels (dia betes, branch or central retinal vein occlusion; see BOX), retinal tears, retinal de- tachm ent or trauma. Small extravasations of blood produce vitreous \202 oat- ers, (seen by the patient as small black dots or tiny ring-like forms with clear centers) which may not grea tly obscure vision. With a large enough bleed to obscure vision, there is no red re \202 e x and the retina may not be seen. A B-scan ultrasound is needed to identify a cause in this situation. VH undergoes sponta- neous absorption. In dense VH a vitrectomy is done to remo ve the blood in the vitreous if the retina is torn/detached or the patient needs treatment of new vessels. In diabetic patients who have previously had photocoagulation for new vesse ls with recurrent VH, it is acceptable to wait 3 months for resolution. Subacute loss of vi sion Optic neuritis ( \201 g 2) Unilateral loss of acuity occurs over hours or days. Color vision is aff ected (dyschromatopsia): reds appear less red, \200\230red desaturation \200\231 \200\224and eye movements hurt. The pupil shows an aff erent defect (p424). The di sc is normal in 60%, swol- len (papillitis) in 23%, blurred and/or hyperaemic in 18% (+hem orrhages in 2%). Temporal pal- lor occurs in 10% suggesting a past attack of optic neuritis in the same eye. Recovery is usual over 2 \200\2236 weeks, but 45 \200\22380% develop mult iple sclerosis (MS) in the next 15yrs. Other causes: syphilis, Devic \200\231s demyelinatio n, Leber \200\231s optic atrophy, diabetes, vitamin de \201 ciency. \201\227: High-dose m ethyl prednisolone for 72h (250mg/6h IV), then prednisolone (1mg/kg/d PO) for 11 days may b rie \202 y delay onset of MS (no change to long-term disability). 70 Transient visual loss \200\207Always think of vascular causes, such as platelet \200\223 \201 brin/cholesterol micro- emboli from atherosclerotic plaques in the heart or carotid arteries (any stenosis or bruit?). 71 Be cau- tious in diagnosing migraine for the 1st time if aged >50yrs. 434 \200 Fig 1. Vitreous hemorrhage. y g o o m a h t h p O l l Fig 2. Optic neuritis Typical causes: \200 Vascular; TIA; migraine \200 Multiple sclerosis \200 Subacute gl aucoma (not always painful) Papilloedema 435 Central retinal artery occlusion There is dramatic visual loss within seconds of occlusion. In 90% acuity is \201 nger counting or worse. An aff erent pupil defect (p424) appears w ithin sec- onds and may precede retinal changes by 1h. The retina appears white, with a che rry red spot at the macula ( \201 gs 1 \200\2232, p436). Exclude temporal arteritis. Occlu sion is often thrombo-embolic (clot, tumor, infective etc). Look for signs of atheroscleros is (bruits; BP \200\200), heart valve disease, diabetes, smoking, or lipids \200\200. 72 \200 If seen within 6h of onset aim is to increase retinal blood \202 ow by reducing intr aocular pressure by ocular massage, surgical removal of aqueous from the anterior chamber o r the use of antihypertensive treatment. NB: \202 uo- rescein angiography may show branch retinal artery occlusion. 73 Hyperbaric oxygen has been tried ( 70% get improved acuity). 74 y g o o m l a h t h p O l If a single branch of the retinal artery is occluded, the retinal and visual changes relate only to the part of the retina supplied. Retinal vein occlusions: central or branch vein? Central retinal vein occlusion (CRVO) Inci dence increases with age. It is commoner than arterial occlusion. Causes/associations: arte riosclerosis, BP \200\200, diabetes and polycythaemia; glaucoma (all types). If the whole c entral retinal vein is thrombosed, there is visual loss (eg acuity reduced to \201 nger c ount- ing). It is less sudden than central retinal artery occlusion. Visual loss may be per ceived as sudden by the patient but the mechanism is of visual loss is due to the developme nt of ischaemia and macular oedema. CRVO is divided into non-ischaemic and ischaemic (with cotton wool spots, swollen optic nerve, macular oedema, and risk of neovascularization; hen ce need for follow-up). Non-ischaemic forms have better acuity (even 6/6) and prognosis (si gns are less dramatic too). But this can convert to the ischaemic form in 30%; hence the ne ed for follow-up. A fundus \202 uorescein angiogram is used to determine the degree of is chaemia and pan-retinal photocoagulation is given to prevent or treat neovascularization. U nfortunately even if the macu- lar oedema resolves anatomically visual prognosis is poor. A im to prevent rubeotic glaucoma and a painful eye (beracizumab and ranbizumab (Lucentis ( p439)) can treat the macular oedema), 75 as can lasers and dexamethasone intravitreal impla nts. NICE 2011 Branch retinal vein occlusion Signs: Unilateral visual loss and fundal ap- p earances in the corresponding area. Retinal ischaemia leads to release of vascular endothel ial growth factor (VEGF) and retinal new vessel formation. Treatment of neovascularization is with laser photocoagulation. Macular oedema persisting for months without improvement ma y receive grid pat- tern argon laser photocoagulation ( arterial crimping). 76n=72 Diagno sis and diff erential diagnosis Other causes of sudden loss of vision: \200 Retinal detac hment (p444) \200 Acute glaucoma (painful, p430) \200 Migraine. Stroke patients may com plain of monocular blindness but visual \201 eld testing will usually reveal a homonymous hemianopia. Sudden bilateral visual loss is unusual (may be CMV infection in HIV patients, p448). Retinal vascular occlusion 436 y g o o m a h t h p O l l Figs 1 \200\2235. Retinal artery occlusion (both the above images) and central retinal vein occlu- sion (right).1 With arterial occlusion note retinal pallor and the cherry-red macul a. With central retinal vein occlusion note hyperaemia and hemorrhages \200\224known as the stormy sunset appearance (last \201 gure). 1 We thank Dr R K Reddy, Dr Badrinath, and Dr Ravishankar (Sankara Nethralya, Chennai, Indi a) for their help with this page, and for permission to reproduce these images. 437 y g o o m l a h t h p O l Gradual loss of vision Be aware that for many, the chief question is likely to be "will I g o blind?": be optimistic where pos- sible. Patients may not tell you that they also fear th ey are going mad, having complex visual hal- lucinations, often of faces. These occur witho ut psychiatric signs and are often related to failing vision in the elderly: the Charles Bo nnet syndrome (p463). 77 Choroiditis (choroidoretinitis) The choroid is part of the uvea (i ris, cili- ary body and choroid), and in \202 ammatory disorders aff ecting the uvea may a lso aff ect the choroid. The retina may be invaded by organisms which set up a granulomatou s reaction (which can be mistaken for a retinoblastoma). Toxoplasmosis and toxocara are mor e common than TB. Sarcoidosis is an- other cause. Tests: CXR; Mantoux; serology. In the acu te phase, vision may be blurred, a gray \200\223white raised patch is seen on the retina, v itreous opacities oc- cur, and there may be cells in the anterior chamber. Later, a choroid oretinal scar (white patch with pigmentation around) will be seen, these being symp- tomles s unless involving the macula. Treat the cause. Choroid melanomas are the commonest maligna nt tumor of the eye. Ap- pearing as mottled gray/black on the fundus, they can cause retina l detach- ment over the growth. Spread is haematogenous or by local orbit invasion. Treatme nt: Enucleation, plaque radiotherapy, local tumor irradiation, photo- coagulation, transpup illary thermotherapy & microsurgical resection. Age-related macular degeneration (ARMD) is the chief cause of registrable blindness.UK Cause: behavioral/nutritional factors (eg \200 \201B12) 78 and (epi)genetic mechanisms.2 It occurs in the elderly who present with deterio rating central vision. There is pigment, drusen (BOX & \201 g 2) and sometimes bleeding a t the macula. ARMD is categorized as dry or wet. Dry ARMD shows mainly drusen and degenerat ive changes at the macular. It progresses slowly. Wet ARMD occurs when aberrant vessels gro w from the choroid into the neuro-sensory retina and leak (choroidal new vessels: CNV). Vis ion deteriorates rapidly and distor- tion is a key feature. Ophthalmoscopy shows \202 uid exudation, localized detach- ment of the pigment. Treatment is available for wet ARMD (BOX ). Be prompt as substantial visual loss may occur while the patient waits. 79 Patients are advised to stop smoking and have a diet rich in green vegetable. Gradual loss of vision in teenagers Think of Stargardt macular degenera- tion and look for prominent yellow \202 ec ks in the retina. This condition was the \201 rst to be treated with embryonal stem cells . Tobacco \200\223alcohol amblyopia From cyanide radicals, when smoking and alco- hol exces