Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Ocular Ischaemic Syndrome

Background Ocular ischaemia is most commonly secondary to carotid artery atherosclerosis, usually in patients aged >50 years. Less common causes include ophthalmic artery occlusion, carotid aneurysm, giant cell arteritis, and vasospasm.

Symptoms Visual loss (sometimes precipitated by bright light), pain (≈40%), and transient visual obscuration (10% have coexisting carotid emboli).

Signs

■Reduced VA

■Anterior segment: rubeosis iridis, elevated IOP, anterior chamber flare or cells, and cataract.

■Posterior segment : common features are retinal arterial attenuation, venous dilatation, retinal haemorrhages, disc neovascularization, and cherry-red spot at the macula. Others include retinal neovascularization, microaneurysms, cotton-wool spots, vitreous haemorrhage, and spontaneous arterial pulsations (spontaneous venous pulsations are normal).

History Ask about cardiovascular risk factors and features of giant cell arteritis.

Examination Check BP, blood sugar, and temporal arteries. Perform digital ophthalmodynamometry by lightly pressing on the upper lid whilst viewing the proximal retinal arteries; reduced perfusion pressure causes the arteries to pulsate.

Differential diagnosis For the causes of rubeosis iridis, retinal haemorrhages, neovascularization, and cherry-red spot at the macula, see pages 440–447. Specifically, consider retinal vein or artery occlusion, diabetic retinopathy, and giant cell arteritis.

Investigations Fluorescein angiography shows patchy choroidal filling and increased retinal and choroidal transit times (normal values, p. 419), vascular staining, and macular oedema in some cases. Carotid artery ultrasound usually shows >90% obstruction.

Management Discuss >60% carotid stenosis with a vascular surgeon. Note IOP may rise if subsequent endarterectomy improves ciliary body perfusion. Ask the patient’s GP to manage any cardiovascular risk factors. Consider panretinal photocoagulation for disc, retinal, or iris new vessels. Inflammation is typically just mild flare and does not require treatment, but

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consider topical steroids if there are cells or discomfort. In eyes with visual potential, consider brimonidine as a first-line treatment of raised IOP due to its possible neuroprotective effect. Cyclodiode is sometimes required if topical therapy fails.

Juxtafoveal Telangiectasia

(Parafoveal Telangiectasia)

Background A condition in which the parafoveal capillaries have irregular, sacular dilatations, and very occasionally capillary obliteration. Typically presents at age 40–60 years. Also called parafoveal telangiectasia.

Classification Classified into four groups (Table 10.1). Group 2 is the most common and is characterised by ‘right-angle’ capillaries, opaque perifoveal retina, inner retinal crystals, and RPE hyperpigmentation that may simulate adult Best’s disease.

Examination Full ocular examination including retinal periphery. Check BP.

Differential diagnosis See page 443.

Investigations

■Fluorescein angiography : Features include: telangiectatic vessels; outer retinal hyperfluorescence; RPE hyperpigmentation that may mask choroidal fluorescence. An example is shown on page 445 (Fig. 10.19). Choroidal neovascular membranes sometimes occur in Group 2.

■Blood glucose : reported associated with diabetes and the features may appear similar.

■Electrophysiology : if Best’s disease is suspected.

Treatment Laser is not proven and is only considered in cases with visually significant exudates and oedema that can be treated without applying laser to the foveal avascular zone. This is more likely to help in Group 1 disease.

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Sickle Cell Retinopathy

Background Different mutations in the beta-haemoglobin gene produce either HbC or HbS, and subsequently homozygous HbSS (sickle cell disease), HbSC (sickle cell haemoglobin C disease), and HbAS (sickle trait). Patients with HbSC are at higher risk of eye disease than those with HbSS.

Clinical features

■Conjunctiva : dark-red, comma-shaped vessels particularly in the inferior bulbar conjunctiva.

■Iris : focal iris atrophy and neovascularization.

■Angle : sickled red blood cells in the anterior chamber can elevate the IOP. Many clinicians avoid or minimize the use of mannitol or acetazolamide in sickle patients, particularly those with intraocular haemorrhage, as this may theoretically increase sickling via dehydration and acidosis. Despite the theoretical risk, there are very few clinical reports of acetazolamide producing a sickle crisis.

■Retina :

1. Angiod streaks.

2. Focal collections of superficial or pretinal haemorrhage that are initially bright red but degrade to form a ‘salmonpatch haemorrhage’. Residual haemosiderin may produce refractile bodies (iridescent spots) and secondary RPE migration may leave intraretinal pigment (Fig. 10.41).

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3. Vessels : increased tortuosity, silver wiring, central and branch retinal artery occlusion, microhaemorrhages, peripheral ischaemia and vascular loops, enlargement of the foveal avascular zone, macular ischaemia and thinning. Retinopathy is classified as:

a. Stage I: peripheral ischaemia.

b. Stage II: peripheral anastomoses that do not leak fluorescein.

c.Stage III: sea fan peripheral neovascularization that leaks fluorescein (Fig. 10.42).

d.Stage IV: vitreous haemorrhage.

e.Stage V: tractional and/or rhegmatogenous retinal detachment.

■Choroid : vaso-occlusion that may produce secondary RPE and outer retinal damage.

Differential diagnosis For causes of neovascularization, see page 440.

Investigations Test sickle status, if this is not known. Consider fluorescein angiography and angioscopy if retinal neovascularization is suspected. Angioscopy utilizes intravenous fluorescein and an ophtalmoscope with a blue filter to detect peripheral leakage not visible on a fundus camera.

Treatment Although some clinicians advocate scatter photocoagulation (0.2 seconds, 500 μm spot size, grey-white burns, one burn width apart) in the area of nonperfusion for problematic stage III disease, this is rarely required, as many sea fans autoinfarct.

Follow–up The value of regular review in those who are asymptomatic is doubtful. Vitreous haemorrhage requires 2–4 weekly retinal ultrasounds if the fundus view cannot exclude retinal detachment. Refer for possible vitrectomy if there is nonclearing vitreous haemorrhage (within 3–6 months), tractional macular elevation (within 1 month), or rhegmatogenous retinal detachment (same day).

Eales’ disease

Eales’ Disease

Background Rare, idiopathic, occlusive, peripheral vasculitis typically affecting healthy adults aged 20–30 years. More common in India and the Middle East.

Clinical features Common retinal features are vascular sheathing (venous > arterial), haemorrhage, peripheral ischaemia (collaterals, neovascularization, vascular tortuosity, sclerosed vessels), and vitreous haemorrhage. Rubeotic glaucoma, disc new vessels, macular oedema, branch retinal vein occlusion (BRVO), macular holes, and tractional or rhegmatogenous retinal detachment may occur. Vitritis and anterior uveitis are mild or absent. The disease is usually bilateral although often asymmetric at presentation (Fig. 10.43).

Differential diagnosis Consider diabetic retinopathy, sickle cell retinopathy, isolated BRVO, sarcoidosis, collagen vascular diseases, and Coats’ disease.

Investigation Fluorescein angiography shows vascular staining and leakage. Other tests are chosen as indicated to exclude other disease, e.g. glucose, sickle testing, ANA, sACE, CXR.

Treatment Scatter photocoagulation in areas of ischaemia may lead to regression of neovascularization. Refer nonclearing vitreous haemorrhage or retinal detachment for possible vitrectomy.

Pseudophakic macular oedema (irvine-gass syndrome)

Pseudophakic Macular Oedema

(Irvine-gass Syndrome)

Background Macular oedema occurring 1–12 months after cataract extraction. Thought to be caused by inflammation, although anterior chamber activity is typically mild or absent. More common if surgery is complicated by vitreous loss (10–20% versus 1%).

Symptoms Initially good VA, then gradual central blurring.

Signs Macular oedema, often cystic.

History and examination Exclude diabetes, uveitis, retinitis pigmentosa, vitreous traction, and retained vitreous lens material as contributory factors.

Investigations Fluorescein angiography classically shows optic nerve and petalloid macular leakage (p. 422). OCT shows macular thickening (p. 447).

Management The evidence base is poor but consider G. ketorolac (Acular) 0.5% and G. dexamethasone 0.1%, both q.d.s. for 2 months then taper over 1 month. Reinstate if the oedema recurs when treatment is discontinued. If oedema persists after 3 months, add acetazolamide 250 mg s.r. b.d. or triamcinolone (Kenalog) 40 mg as a sub-Tenon’s injection (avoid if steroid responder). Trials of intravitreal triamcinolone are in progress. Surgically relieve any anterior or posterior chamber vitreous traction.

Follow–up Two monthly whilst on treatment.