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 s are combined. Signs: optic atrophy ( \201 g 1); loss of red/green discrim- ination (earl y) scotomata. Vitamins may help (B1, B2, B6, B12, folic acid). 80 Optic atrophy Disks are p ale (degree doesn \200\231t cor relate with visual loss). It may be from \200\200intra- oc ular pressure (glaucoma), or retinal damage (choroiditis, retinitis pigmentosa, cerebromacu - lar degeneration), or be due to ischaemia (retinal artery occlusion). Causative toxins: T obacco; methanol; lead; arsenic; quinine; carbon bisul \201 de. Other causes: Leber \200 \231s optic atrophy (p648), mul- tiple sclerosis (MS), syphilis, external pressure on the n erve (intraorbital or intracranial tumors, Paget \200\231s disease aff ecting the skull). E xamine the cerebellum and eye move- ments: nystagmus in the abducting eye suggests MS (or s troke or DM); in the el- derly look for temporal artery pulselessness (or a scar from a pre vious biopsy). 438 \200 Typical causes \200 Cataract \200 Macular degeneration \200 Glaucoma (p440) \200 Di abetic retinopathy \200 Hypertension (p448) \200 Optic atrophy (below) \200 Slow reti nal detachment y g o o m a h t h p O l l Fig 1. Optic atrophy. 439 Use of services by older patients with failing vision There is good evidence in the UK of u nder-use of services by older people. Pop- ulation-based cross-sectional studies in primary care show that prevalence of bilateral visual impairment (acuity <6/12) is 30%. Most of t hese are not in touch with ophthalmic services. \200\207Three-quarters of these have remed iable problems. In one study, 20% had acuity in one or both eyes of <6/60 ( \200\230blind \200\231). Typical causes were found to be cataract (30%), macular degeneration (8%), and u ndiagnosed chronic glaucoma. 81n=1547 Optic nerve drusen Drusen signify optic nerve-head axonal degen- eration. Abnormal axonal m etabolism leads to intracellular mitochondrial calci \201 cation. Some axons rupture and m itochondria are extruded into the extra-cellular space. 82 Calcium is de- posited here, and drusen form. The optic disc edge is made irregular by the lumpy, yellow matter. The optic cup is absent and vessels show abnormal branching patterns. 83 y g o o m l a h t h p O l Fig 2. Optic drusen. Mr C Chau. Managing age-related macular degeneration (ARMD) Arrange a \202 uorescein angiogram at th e outset and then 4 \200\2236-weekly reviews with a photograph and an OCT (optical coherenc e tomography). Intravitreal vascular endothelial growth factor (VEGF) inhibitors: Ben- e \201 ts: \200\200acuity; \200\201cell proliferation, \200\201formation of new blood vess els, \200\201vascular leaks. 84 Monthly bevacizumab (Avastin ) and ranibizumab (Lucentis ; NICE approved) injections for 1yr give the same acuity bene \201 t ( 8 more letters see n on the chart). Avastin is far cheaper but may have more SE (24% vs 19%). 85 CATT study Laser photocoagulation: May be used in eyes with speci \201 c signs on \202 uo- rescein angiography and juxtafoveal or extrafoveal lesions only. Persistent or recurrent CNV occurs in 50% of treated eyes within 3 years of therapy. Intravitreal steroids: Triamcinolone is an adjunct to PDT & VEGF inhibitors. 86 Screening: Once signs of ARMD are seen, patients e xplain about reporting signs of neovascularization: a good self-test is \200\234do straigh t lines on graph paper appear straight? \200\235. Refer if distortions or sudden blank spot s. 87 If these measures are inapplicable: Most must rely on visual aids (eg mag- ni \201 e rs) to read. Advise a diet rich in fruit and leafy green vegetables, with supplements if th is diet causes problems. 88 Antioxidants/vitamins: AREDS (Age-Related Eye Disease Study 89) \200\230established \200\231 that supplement- ing diets with zinc, \200 -carotene, and v itamin C & E slowed AMD progression.1 Recently lutein, zeaxanthin, B vitamins, and omega-3 fatty acids are also re- ported to \200\201progression, while vitamin E and \200 -caroten e where found to \200\200risk of late AMD, so more trials are under way (AREDS2). 89,90 NB : antioxidants may have unintended, even fatal consequences: 91 so be cautious! N=1208 1 Studies of monozygotic AMD-discordant twins: the twin with more advanced AMD, larger drus en, and pigment area tended to be the heavier smoker. The twin with the earlier stage tende d to have \200\200dietary vitamin D, betaine, and methionine intake. 92 Chronic simple (open angle) glaucoma Glaucoma implies optic neuropathy with death of many r etinal ganglion cells and their optic nerve axons. It is asymptomatic until visual \201 e lds are badly im- paired; hence the need for screening. If \200\200intraocular pressure (I OP) is found, life- long follow-up is needed ( \211 yearly; more often early on). It accoun ts for 7% of new blind registrations. Visual \201 eld loss may manifest as dangerous diff i culty dodging cars while crossing busy roads. 93 De \201 nition/pathogenesis Glaucoma is present when, on \201 eld testing, 3 or more locations are outside normal limits, and th e cup-to-disc ratio1 is greater than that seen in 97.5% of the population. IOP may be raise d, but this is not part of the de \201 nition. Susceptibility of a patients retina and opt ic nerve to IOP related damage is very variable. IOP \200\20621mmHg may or may not correla te with cupping (deepening and excavation), nerve damage, with scotomata (sausage-shaped \201 eld defects near the blind spot, which may coalesce to form big defects). Nasal and su perior \201 elds are lost \201 rst (temporal last). Normal cups are similar in shape an d occupy <50% of the disc. In glaucoma these enlarge (esp. along vertical axis). As damage progresses the disc pales (atrophy), and the cup widens and deepens, so vessels emerging fr om the disc appear to have breaks as they disappear into the cup and are then seen at the b ase again ( \201 gs 1 \200\2232). Notching of the cup and hemorrhage at the disc may occur . Since the central \201 eld is intact, good acuity is maintained, so presentation is oft en delayed until irreversible optic nerve damage. Control of IOP does stop visual \201 el d loss but does not reverse it. 94 Some get glaucoma with normal IOP (eg if retrobulbar blo od \202 ow \200\201). 95 Screen if at high-risk >35yrs old (typical age at detection: 60y rs) with +ve family history (esp. siblings); African-Caribbean; myopia; diabetic/thyroid ey e disease. Technology is making primary prevention cost-eff ective. Tests must be combined, as follows, in order of eff ectiveness: \200 Multiple stimulus static visual \201 eld screening \200 Documenting optic disc cupping \200 IOPs \200\200. 96,97 Follow-up of \201 IOP: 98 Accredited community-based optometrists with a special interest (OSIs) in glau coma may reduce what is a huge task for hospitals. \200\2042012 Drugs treatment Reduce IOP by 30% of baseline. Surgery is used if drugs fail. \200 Prostaglandin analogs (latanopro st 50 g/mL; travoprost) \200\200uveoscleral out \202 ow. Dose: once daily (evenings). SE : red eye, iris color change, periocu- lar skin pigmentation, eyelash growth. \200 \201 \230-blockers (timolol 0.25 \200\2230.5% or betaxolol 0.5%) use twice daily (/24h for Timop tol LA ) to \200\201production of aqueous. They are \200 -blockers. ( \200\230 caution i n asthma or heart failure; systemic absorption occurs with no 1st-pass liver metabolism.) S E: dry eyes, corneal anesthesia, allergy, \200\201exercise tolerance. 99 \200 \200 -adr energic agonists (brimonidine, apraclonidine) \200\201production of aqueous and \200\200u veoscleral out \202 ow. SE: lethargy dry mouth. \200 Carbonic anhydrase inhibitors (dorz olamide & brinzolamide drops, aceta- zolamide PO) \200\201production of aqueous. SE of ace tazolamide: lassitude, dyspep- sia, K+ \200\201, paraesthesiae. Avoid if pregnant. \200 M iotics (pilocarpine 0.5 \200\2234% drops) \200\201resistance to aqueous out \202 ow. It c au ses miosis, acuity \200\201, and brow ache from ciliary muscle spasm. Use 4 times daily. \200 Sympathomimetic (dipivefrine 0.1% drops). Caution if heart disease, BP \200\200, an d closed angle glaucoma. SE: sore, smarting, red eyes/vision \200\201. Use 12-hourly. \200 Fixed-dose combination drops: Can give the best 24h effi cacy NB: dorzola- mide + timolol is better than brimonidine + timolol. 100 Surgery: Trabeculectomy is a \201 ltration sur gery that establishes a pressure valve at the limbus so aqueous can \202 ow into a conjun ctival bleb. Problems include early failure, hypotony, bleb leakage, infection (normal heal ing can cause bleb failure, but this can be delayed by topical cytotoxics, eg \202 uorour acil). Eff ects of argon laser trabeculoplasty are often brief: its role may be in the elde rly. Follow-up Equipment and regimens are complex, and must conform to NICE ad- vise; 4 \200\2236-monthly visits may be needed if IOP is off target and risk of developing chronic open angle glaucoma is high (take into account age, IOP, corneal thickness, appearance and size of the optic nerve head). If favorable, monitor every 1 \200\2232yrs. 440 (closed angle: p430) \200 y g o o m a h t h p O l l Optic disc cupping is characterized by loss of disc substance \200\224hence enlarge- ment o f the cup. Normal cup:disc ratio 0.4 \200\2230.7. 101 This depends on the size of the disc: \200\207a large cup in a small disc is proba- bly pathological.1 As cupping develops, the disc vessels are displaced nasally. Asymmetric cupping suggests glaucoma. The cup:disc rat io is increased to >0.4 ( \201 g 1). If the cup : disc ratio is >0.9, cupping is said to b e severe. 102 Notching at the neuroretinal rim is usually inferior, and best seen where the vessels enter the disc. The sharp turning of the vessels is Mr C Chau. called bayoneting . 103 Progression is more related to the size of the neuro-retinal rim than to lack of disc size. 104 Glaucoma aff ects the anterior visual pathway at least up to the optic chiasm, t o an extent that correlates with glaucomatous optic nerve damage. 441 y g o o m l a h t h p O l Fig 1. Cupped disc. Fig 2. This patient has open angle glaucoma which hasn \200\231t yet damaged the right disc . The left optic disc is grossly cupped and atrophic. Reproduced from Parr, Introduction to Ophthalmology, with permission from University of Otago Press. Educating people about their glaucoma It is common for people to be seen regularly for years in the glaucoma clinic and yet under stand almost nothing about their condition. \200\234This is their fault \200\224if they as ked, we \200\231d be delighted to tell \200 \200\235 But it \200\231s really our fault and we should do better, as lack of knowledge is dangerous and demoraliz- ing. In one study 80 % thought that glaucoma drops could have no systemic eff ects, and 48% believed symptoms wo uld warn them of disease progres- sion. 30% of new patients believe that blindness is likel y. 105 . P O I \200\201 n a h t a m o c u a l g So try to explain what happens in glaucoma, and give printed details (check that the patien t can read them!), and stress that they should let their doctors know that they are on glau coma treatment. \200\234Can I do anything to help myself? \200\235 Possibly: reducing oxid ative stress in mitochondria can be protective, eg with gingko, dark chocolate, polyphenoli c \202 avonoids (in tea, coff ee, red wine), melatonin, and anthocyanosides2 eg in bilber riesuk (Vaccinium myrtillus) and blueberriesusa (V. corymbosum).v106,107. o t e r o m s i e r e h T 1 Normal small disks (1.0 \200\2231.3mm) have small cups and normal big disks (>1.8) have l arge cups, so large normal disks may be misnamed glaucomatous. Mean disc diameter: 1.5mm. M ean cup : disc ratio is 0.35, 0.45, & 0.55 for small, medium and big disks (95th centiles for upper limit of normal are 0.59, 0.66, & 0.74). 108 2 Anthocyanosides (eg from fresh or dried blueberries 109) have interesting eye eff ects: they \200\201problems from retinal i n \202 ammation and help night vision in myopes, eg with asthenopia (eye strain/pain, blur red vision, headache and occasional double vision on reading, computer work, or tedious vis ual tasks). Cataract 110 \200\207When a cataract is found, measure fasting plasma glucose (to exclude DM). \200\207Any opacity in the lens is called a cataract. \200\207The 4 major causes of blindness in the world are cataract, vitamin A de \201 ciency, trachoma, and onchocerciasi s. Cataracts are found in 75% of over 65s but in only 20% of 45 \200\22365-year-olds. Ophth almoscopic classi \201 cation is by lens appearance. With immature cataracts the red re \202 ex still occurs; if dense cataract there is no red re \202 ex, or visible fundus. Nuc lear cataracts change the lens refractive index and are common in old age, as are cortical spoke-like wedge-shaped opacities. Ante- rior and posterior polar cataracts are localized, commonly inherited, and lie in the visual axis. Subcapsular opacities (eg from steroid use) are just deep to the lens capsule \200\224in the visual axis. Dot opacities are common in normal lenses but are also seen in fast-developing cataracts in diabetes or dystrophia myot onica. Presentation Blurred vision; unilateral cataracts are often unnoticed, but loss of s tereopsis aff ects distance judgment. Bilateral cataracts cause gradual loss of vision (fre quent spectacle changes as refraction changes) dazzle (esp. in sunlight) monocular di plopia. In children they may present as squint, loss of binocular function, or a white pupi l, or as nystagmus (infants)/amblyopia. Surgery Mydriatic drops, sunshades/sunglasses help a bit, but if symptoms are troubling, lifestyle is restricted, or if unable to read a numbe r-plate at 67 feet (and they need to drive) off er surgery.1 Explain risks: 2% get serious compli- cations; even if surgery may vastly improves vision, eyes may not be entirely norma l after (dazzle/glare often remains). Distant spectacles are often needed too. >30% have co -existing macular degeneration,et al which limits outcome. 442 \200 y g o o m a h t h p O l l The ideal is day-case surgery using local anesthesia with small-incision surgery and phacoe mulsion + a intraocular lens (IOL) implant. This applies to the vast majority of patients. Younger people, high myopes, and the squeamish may prefer general anesthesia. An incision o f 3mm is made, and the lens is removed by phacoemulsion (ultrasound breaks it up: it is th en aspirated into a cannula). The incision is fractionally enlarged and an arti \201 cial lens (eg of Perspex, acrylic, or silicon) implanted. Lenses are foldable so they can be put through a smaller incision. The patient can usually return home immediately afterwards. A dressing may be needed for a few hours. With phacoemulsi \201 cation, full activities can be resumed next day. With complicated surgery or extracapsular extraction, a larger incisio n is needed and there may be more limitations. Patients use antibiotic and anti-in \202 am matory drops for 3 \200\2236 weeks post-op. Then they need to change spectacles to get the full bene \201 t of surgery. Multifocal IOLs exist and in appropriately selected patients they can be helpful. Post-op complications: Post-op posterior capsule thickening is common. It is deliberately left at surgery to make surgery safer. It opaci \201 es in 20%, over months or years post-op; it seems \200\234like my cataract returning \200\235. It is easil y treated by capsulotomy with a Yag laser as an outpatient. As refraction is corrected, astigmatism is more noticed. This can be corrected during surge ry (eg by toric intraocular lens or eyeball shape change by placing the incision in the exa ct right place) in the light of pre-op biometry. Some eye irritation needing additional or altered drops post-op is common. Some may have an terior uveitis requiring new medication. Rarely, there may be vitreous hemorrhage, retinal detachment, or glaucoma ( permanent visual loss), and endophthalmitis (<3/10,000; but pse udomonal clusters may occur). Prevention/photoprotection 1 Use sunglasses (UV-B \200\201). 111 2 \200\201Oxidative stress (esp. in smokers, with antioxidants, eg vitamin C and caff eine etc). 112,113 1 Don \200\231t support arbitrary thresholds of acuity, eg \200\230both eyes <6/12 \200 \231, adopted by some cash-poor NHS PCTs. 443 Cataract risk factors Most cataracts are age related. In children, many are genetic (?some genetic in \202 uence in adults too). Cataracts occur early in: diabetes mellitus; with to pi- cal, oral, or inhaled steroid use; with high myopia; dystrophia myotonica. Pre- and pos t-operative care Prior to surgery ocular biometry must be done. This is a measurement of th e curvature of the cornea and the length of the eye which enables prediction of the suitabl e intraocular lens implant for the patient ( \201 g 1). In most cases it is aimed to leave the patient emmetropic (in focus for distance), or just slightly myopic, but this may vary considerably depending on patient preference and pre-existing refraction. It is not an exa ct science as the clinical measurements vary and many people do continue to wear spectacles post-operatively for a remaining refractive error \200\224but heightened patient expectati ons for precise post-operative refractive results make biometry vital. 114 y g o o m l a h t h p O l On obtaining new spectacles many experience symptoms of imbalance; these should settle in 2 \200\2233 weeks. If they do not, recommend return to the op- tometrist to check the correc t spectacles have been dispensed. If there is still a continuing problem they should return to the ophthalmologist. If patients develop a painful red eye or loss of vision post-operatively they should be ref erred back to the ophthalmologist urgently to deal with possible complications. Many experi ence awareness of the eye or dry, or gritty sen- sations and lubricants such as Viscotears may help. If vision deteriorates with time they should initially visit the optometrist to see if they need a new prescription change; and thereafter the ophthalmologist to consider Yag laser capsulotomy or exclusion of other problems. Fig 1. Position of the intraocular lens after cataract surgery. Cataracts at birth: \200\207act within 4 weeks! If there is a congenital cataract the pati ent needs to be referred urgently to ophthalmology for surgical consideration. Intervention needs to be done within the latent period of visual development (1st 6 weeks of life) to p revent signi \201 cant deprivation amblyopia. Do a TORCH screen too (p35).115 The retina The retina consists of an outer pigmented layer (in contact with the choroid), a nd an inner sensory layer (in contact with the vitreous). At the center of the posterior pa rt lies the macula: at its center lies the fovea ( \201 g 1, p447). This has many cones, s o acuity is greatest here. 3mm medial to the fovea is the optic disc, which contains no ro ds or cones (the visual \201 eld \200\231s blind spot). Optic disc Think color; contour; cup. Color should be a pale pink. It is more pallid in optic atrophy (p438). Contour: the d isc may appear oval in astigmatic eyes, and appear abnormally large in myopic eyes. Disc ma rgins are blurred in papilloedema (eg from raised intracranial pressure, malignant hyperten sion, cavernous sinus thrombosis), and with optic neuritis. Blood vessels radiate away from the disc. The normal arterial/venous width ratio is 2 : 3. Venous en- gorgement appears in retinal vein thrombosis; abnormal retinal pallor with artery occlusion; and hemorrhages + exudates in hypertension and DM. Cup: the disc has a physiological cup which lies centrally and should occupy \205\223 of the disc diameter. Cup widening and deepening occurs in gl aucoma (p440). Retinal detachment (RD, \201 g 1) 116 may be rhegmatogenous,1 following se paration of the vitreous leading to a retinal tear then detachment; secondary to some intra ocu- lar problem (eg melanoma, or \201 brous bands in the vitreous in diabetes), occur af ter cataract surgery and trauma (reti- nal dialysis). Myopic eyes are more prone to detachm ent, the higher the myopia, the greater the risk \200\224and cataract surgery for myopia ca rries \200\200risk of detachment. 444 Retinoblastoma: see p421. \200 y g o o m a h t h p O l l Fig 1. RD; note retinal folds (1 \200\2233 o \200\231clock) & distorted disc. Bristol Eye Hospital. In retinal detachments, holes/tears in the retina allow \202 uid to separate the sen- sor y retina from the retinal pigment epithelium. If a retinal break is identi \201 ed before a detachment occurs, cryo/laser retinopexy may be preventive. Detachment presents with 4 \200\230F \200\231s : floaters, flashes (in 50%), field loss, and fall in acuity \200\224painless and may be as a curtain falling over the vision (eg the curtain falls down as the lower half of the retina detaches upwards). Field defects indica te position and extent of the detachment (in superior detachments \201 eld loss is inferi or). Ophthalmoscopy: gray opalescent retina, ballooning forward. Extensive detachment of th e retina will pull off the macular. If it does detach, central vision is lost and doesn \200\231t always recover completely even if the retina is successfully \201 xed. Rate of detachment varies: upper halves are quicker. \200 Refer urgently, for surgery: vitrectomy and gas tamponade (or silicone oil), scleral silicone implants. Cryotherapy or laser coagul ation is used to secure the retina. Post-op re-detachment occurs in 5 \200\22310%. Retiniti s pigmentosa This is the most prevalent inherited degeneration in the retina. Sporadic type s are more common (mostly autosomal recessive \200\224 but autosomal dominant types have be tter prognosis; X-linked is the rarest form, with poorest prognosis). Through life, 25% ret ain ability to read, with reduced visual \201 elds. Only a few have acuity \211 6/60 at aged 20yrs; but by 50, many are reduced to this level. 117 Novel non-standard therapies: ne ural pros- thetics (arti \201 cial vision by stimulating retinal ganglion cells electrical ly). 118 Toxoplasma This intracellular protozoan may cause \200\230punched-out \200\231 pi gmented chorioretinal scars (seen on fundoscopy; may cause acuity \200\201 \200\201). \200 \224: OHCM p404. 1 Rhegmatogenous derives from Greek rhegma, a discontinuity or a break. 119 Rhegmatogenous reti- nal detachments (RRD) occur when a retinal tear leads to \202 uid accumulation with a separation of the neurosensory retina from the underlying retinal pigment epithelium. It is the commonest type. 445 Macular holes Glasgow \200\231s nomenclature 120 The macula is an area 5.5mm across, just lateral to the optic disc. Its carotenoid pigments give it its color. It nearly corre- spon ds to the histological area centralis (>1 layer of ganglion cells). In its middle is a 1.5m m pit, the fovea ( \211\210fovea centralis; no ganglion cells). This has a tiny area (350 m 121), the foveola (overlapped by the capillary-free zone, 400 m across), where cones are narrow, long and densely packed (300,000/ mm2) compared with cones on the foveal rim ( \201 g 1, p447), which in turn, are narrower and longer than perifoveal cones. 122 This con e gradient correlates with acuity. 123 y g o o m l a h t h p O A macular hole ( \201 g 1) is a full-thickness defect of retinal tissue. It involves the f ovea (visual acuity \200\201). Prevalence: 3.3/1000 in persons >55yrs. There is an approxim ately 12% chance of a similar hole developing in the other eye. Presentation Distorted visi on with visual loss. Look for a tiny punched-out area in the center of the macula: there ma y be yellow-white deposits at the base. Slit lamp exam (with a convex lens, 78D) shows a ro und excavation with well-de \201 ned borders interrupting the slit lamp beam. Often there is semi- translucent tissue suspended over the hole \200\224the hole is typically surrounde d by a gray halo of detached retina. \200\207Refer to a specialist vitreo-retinal surgeon. Pathogenesis Idiopathic focal age-related perifoveal vitreous cortex shrink- age \200\203t angential traction on the fovea \200\203detachment \200\203macular holes. Displace- ment of the fovea reveals the underlying xanthophyll pigment. Stages: 1a Impending hole seen as a yellow spot at the fovea. There is loss of the characteristic foveal depression due to ante rior traction from the vitreous. l 2b Occult hole: donut-shaped yellow ring ( 200 \200\223 300 m) centered on the foveola. Vi sion is usually good at this stage. 50% of holes pro- gress to stage 2 \200\224when treatm ent is needed. 3 Full thickness macular hole (<400 m). with a surrounding cuff of subretin al \202 uid. The cor- tical vitreous is still attached to the fovea. Vision is reduced wi th image distortion. 4 Holes >400 m with localized separation of Fig 1. Macular hole. the vitreous cortex at the macula. Tests Amsler grids (p428) reveal visual distort- ion; optical coherence tomography (OCT, \201 g 2) diagnoses and stages macular holes. Fluoresce- in angiography (FA) helps diff ere ntiate macul ar holes from cystoid macular oedema and choroi- dal neovascularization (CNV). Treatment In stage 1, see what happens (no treatment if there is spontaneous resolution or Quresh Mohamed FCROphth. no progression). Surgery: a vitrectomy is done to remove the vi treous and the internal limiting membrane over the hole is peeled. An air bubble is introdu ced to nudge (tamponade) the macula back into position. The patient spends 1 \200\2232 post -op weeks face down. Series of patients have been variously reported, with hole closure rat es of \211 95% ( 67% improve by \211 2 lines of visual acuity). Success is also possible if the hole is long-standing (>6 months). Fig 2. Stage 4 hole (optical coher- ence tomography). However, in some patients, more than one operation is needed to close the hole, and adverse eff ects may occur: macular retinal pigment epithelium changes, retinal detachments, iatro genic retinal tears, enlargement of the hole, macular light toxicity, postoperative intraoc ular pressure spikes. Many patients develop cataracts (76% of cases requiring extraction wi thin 2 years). Patients not suitable or not wishing for this need visual aids (eg to read). The eye in diabetes mellitus \200\207Keep BP <150/85mmHg and all the major diabetic retino pathies are less com- mon.1 Diabetes can be bloody and blinding \200\224the leading cause o f blindness in those aged 20 \200\22365 (UK). Almost any part of the eye can be aff ected: mainly cata- ract and retinopathy. 30% of adults have ocular problems when diabetes pre- se nts. At presentation, the lens may have a higher refractive index producing relative myopia . On treatment, the refractive index reduces, and vision is more hypermetropic, so don \200 \231t correct refractive errors until diabetes is controlled. Structural changes Diabetes a ccelerates formation and progress of age- related cataract. Typically this is premature sen ile cataract, but young diabet- ics can also be aff ected at presentation; here the lens ha s taken up a lot of glucose which is converted by aldolase reductase to sorbitol. Diabetes causes ocular ischaemia, which can cause new blood vessel forming on the iris (ru- beosis), and, if these block the drainage of aqueous \202 uid, glaucoma may result. Retinopathy P athogenesis: microangiopathy in capillaries, precapillary art- erioles and venules causes o cclusion leakage. Vascular occlusion causes ischaemia new vessels in the retina, opti c disc, and iris, ie proliferative retinopathy. New vessels can bleed (vitreous hemorrhage) . Retraction of \201 brous tissue running with new vessels heightens risk of retinal deta chment. Occlusion also causes cotton wool spots (ischaemic nerve \201 bres). Vascular lea kage: As pericytes are lost, capillaries bulge (microaneurysms) and there is oedema & hard exudates (lipoprotein & lipid \201 lled macrophages). Rupture of microaneurysms at the ne rve \201 bre level causes \202 ame shaped hemorrhages; when deep in the retina, blot he morrhages form. 446 \200 y g o o m a h t h p O l l \200\207Presymptomatic screening enables timely laser photocoagulation. Screen by regular eye exam or retinal photography. Screen all diabetic patients annually in the community, by dilated fundus photography which is then reviewed by a trained screening service. Referral s are then made accordingly. Lesions are mostly at the posterior pole and can be easily see n by ophthalmoscope. Non-proliferative diabetic retinopathy (NPDR) is rated as mild, modera te or severe depending on the degree of ischaemia. Signs comprise micro- aneurysms (seen as \200\230dots \200\231), hemorrhages ( \202 ame shaped or \200\230blots \200\231) hard e xudates (yellow patches), engorged tortuous veins, cotton wool spots, large blot hemorrhage s (the latter 3 are signs of signi \201 cant ischaemia). NPDR can progress to sight-threat ening proliferative retinopathy. Proliferative diabetic retinopathy (PDR): Fine new vessels appear on the optic disc, retina and can cause vitreous hemorrhage. Maculopathy: Leakage f rom the vessels close to the macula cause oedema and can signi \201 cantly threaten vision (clinically signi \201 cant macular oedema). It can exist with otherwise mild retinopathy . \200\207Refer those with maculopathy, severe NPDR, or proliferative retinopathy urgently f or assessment2 and treatment (eg photocoagulation) to protect vision. Treatment Good contro l of diabetes prevents new vessels forming. \200\230Meta- bolic memory \200\231 eff ects m ean that early good control of diabetes with insulin pays dividends later. 124 Pregnancy, d yslipidaemia, BP \200\200, renal disease, smoking, and anemia may accelerate retinopathy. P hotocoagulation by laser is used to treat both maculopathy (focal or grid) and proliferativ e retinopathy (panreti- nal). Intravitreal triamcinolone and anti-VEGF drugs (p439) are use d with laser to treat diabetic macular oedema. See \201 gs 1 & 2. If vitreous hemorrhage is massive and does not clear, vitrectomy may be needed. CNS eff ects Ocular palsies may oc cur, typically nerves III and VI. In diabetic third nerve palsy the pupil may be spared as \201 bres to the pupil run peripheral- ly in the nerve, receiving blood supply from the p ial vessels. Argyll Robertson pupils and Horner \200\231s syndrome may also occur (p424). 1 UKPDS data: N = 1148. Absolute risk for blindness was 3.1 per 1000 patient-years if contro l was tight VS 4.1 for others. There was no diff erence if the BP was lowered by ACE-i or \200 -blockers. 125 2 Fluorescein angiography and optical coherence tomography OCT imaging are important tools here. 447 Fig 1. In this diagram of the retina that is depicted in \201 g 2, where are the le- sion s? In this image of the macular re- gion, a is the foveola, b is the fovea cen- tralis, c i s the parafoveal area, and d is the perifoveal area. 126 See p445 for ana- tomical/histolog ical nomenclature. 127 In day-to-day clinical parlance the word fovea is often used (confus ingly) to refer to fovea centralis and/or the foveola. y g o o m l a h t h p O l The macula is a circle centered on the foveola whose diameter is the distance between the t emporal border of the op- tic disc and the foveola. \200 128 Results of retinal screening in diabetes: when to refer to a surgeon: 1 Maculopathy: If screening shows exudate or retinal thickening within one optic disc diameter of the cent er of the fovea \200 Circinate or other group of exudates within the macula \200 Any micr oaneurysm or hemorrhage within 1 disc-diameter of the center of the fovea, if best visual a cuity is <6/12. 2 There are features of pre-proliferative retinopathy (venous beading; venous loops or reduplications); multiple deep, round or blot hemorrhages. 3 Any unexplained drop in visual acuity. \200 128 4 Proliferative diabetic retinopathy This is treated with panretinal (scatter) laser photo-coagulation (PRP). This type involves tre ating the peripheral retina which is not receiving adequate blood \202 ow. By treating th ese areas, the stimulus driving the neovascular process may be halted. As this treatment in volves many laser applications (eg >1000) it may be divided into \211 2 sessions. NB: panr etinal photocoagulation does not improve vision. It is intended to help prevent blindness. It may cause some loss of peripheral, color, and night vision. Some patients get generalize d blurring of vision which is usually transient but may persist inde \201 nitely. x Fig 3. After the laser. Figs 2 & 3 Prof J Trobe. Fig 2. Retinopathy before the laser.