Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

428 CHAPTER 13 Medical retina

Early phase

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Late phase: point of progressive leakage in an ink-blot type pattern

Figure 13.8 FA of central serous chorioretinopathy.

CYSTOID MACULAR EDEMA (CME) 429

Cystoid macular edema (CME)

This important macular disorder is a common pathological response to a wide variety of ocular insults (Table 13.7). It is thought that prostaglandin secretion and vascular endothelial damage cause fluid accumulation in the outer plexiform layer.

The relatively loose intercellular adhesions of this layer then permit the formation of cystoid spaces, especially in the macular region of layer of Henle. It most commonly arises after cataract surgery (Irvine–Gass syndrome; p. 257) or in association with diabetic maculopathy, retinal vein occlusions, and posterior uveitis.

Clinical features

•Asymptomatic, dVA (may be severe), metamorphopsia, scotomas.

•Loss of foveal contour, retinal thickening, cystoid spaces; central yellow spot, small intraretinal hemorrhages, and telangiectasia (occasional).

•Associated features depend on the underlying cause (e.g., diabetic retinopathy, B/CRVO, uveitis).

•Complications: lamellar hole (irreversible dVA).

retinal thickening.

Treatment

Although there may be some variation according to the underlying cause, a stepwise approach is recommended. Review the diagnosis if condition is atypical or slow to respond. One approach is as follows:

1.Topical: steroid (e.g., dexamethasone 0.1% or prednisolone acetate 1% 4x/day) + NSAID (e.g., ketoro-lac 0.3% 3x/day).

Review in 4–6 weeks; if no response or persisting, then:

2.Periocular steroid (e.g., transeptal/subtenons; methylprednisolone/ triamcinolone) and continue topical agent. Follow up in 3–4 weeks for IOP check.

Review in 4–6 weeks; if persistent, then:

3.Consider repeating periocular or giving intravitreal steroid (triamcinolone 4 mg); vitrectomy with epiretinal or internal limiting membrane peeling; systemic steroids (e.g., prednisone 40 mg 1x/day, titrating over 3 weeks; or IV methylprednisolone 500 mg single dose); oral acetazolamide (500 mg/day; limited evidence).

Prognosis

Prognosis varies according to the underlying pathology. Most patients with CME arising after cataract surgery will attain VA 20/30 within 3–12 months of their operation.

430 CHAPTER 13 Medical retina

Table 13.7 Causes of CME

•Postoperative (cataract, corneal, or vitreoretinal surgery)

•Post-cryotherapy

•Post-laser (peripheral iridotomy, panretinal photocoagulation)

•Uveitis (posterior > intermediate > anterior)

•Scleritis

•Retinal vein obstruction

•Diabetic maculopathy

•Ocular ischemia

•Choroidal neovascular membrane

•Retinal telangiectasia

•Hypertensive retinopathy

•Radiation retinopathy

•Epiretinal membrane

•Retinitis pigmentosa

•Autosomal dominant CME

•Tumors of the choroid or retina

•Medication

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DEGENERATIVE MYOPIA 431

Degenerative myopia

Myopia is common and is regarded as physiological if less than –6D. Of those with high myopia (> –6D), there is a subset in whom the axial length may never stabilize (progressive myopia) and who are at risk of degenerative changes.

The prevalence of progressive myopia varies from 1 to 10%, with geographic variation (highest in Spain and Japan). It is a significant cause of blindness in the developed world and affects the working population.

Risk factors include genetic influences (autosomal dominant/recessive, sporadic; see also Table 13.8) and environmental factors (excessive near work).

Clinical features

• Increasing myopia, dVA, metamorphopsia, photopsia (occasional).

Investigations

•Ultrasound can confirm a staphyloma and can monitor axial length.

•FA: if CNV is suspected.

•OCT is used to determine presence of vitreomacular traction and macular schisis.

Treatment

Choroidal neovascular membranes

•Extrafoveal: consider argon laser photocoagulation. With time, there is often significant expansion of the resultant atrophic zone.

•Subfoveal: PDT is associated with a reduction in visual loss (cf. placebo).

•Anti-VEGF therapy with pegaptanib (macugen), bevacizumab (avastin) or ranibizumab (lucentis) intravitreal injections.

Prognosis

High myopia is the most common cause of CNV in young patients, accounting for >60% of CNV in those under 50 years of age. Risk factors for CNV development are lacquer cracks (29% develop CNV) and patchy atrophy (20% develop CNV). At 5 years following onset of myopic CNV (untreated), around 90% of patients have a VA 20/200.

432 CHAPTER 13 Medical retina

Table 13.8 Associations of myopia

•Stickler syndrome

•Marfan syndrome

•Ehlers–Danlos syndrome

•Down syndrome

•Gyrate atrophy

•Congenital rubella

•Albinism

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Figure 13.9 Myopic degeneration with a large macular staphyloma. See insert for color version.

ANGIOID STREAKS 433

Angioid streaks

Angioid streaks are breaks in an abnormally thickened and calcified Bruch’s membrane. This type of brittle Bruch’s membrane may result from a number of endocrine, metabolic, and connective tissue abnormalities (Table 13.9), but in about half of cases no underlying cause is found.

Clinical features

•Asymptomatic; dVA, metamorphopsia.

•Angioid streaks: narrow, irregular streaks radiating from a peripapillary ring; the color of the streaks varies from red to dark brown depending on background pigmentation.

•Associated features: peripapillary chorioretinal atrophy; local/diffuse RPE mottling (“peau d’orange”; common in PXE); disc drusen.

•Complications: CNV, choroidal rupture (after minor trauma) with subfoveal hemorrhage.

Investigations

Use FA if CNV is suspected; angioid streaks show hyperfluorescence due to window defect.

Treatment

•Conservative: advise patient to avoid contact sports and risk of trauma.

•Extrafoveal/juxtafoveal CNV: consider argon laser photocoagulation.

•Subfoveal CNV: preliminary results suggest that PDT may be of benefit.

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Table 13.9 Causes of angioid streaks

•Pseudoxanthoma elasticum

•Ehlers–Danlos syndrome

•Paget’s disease

•Acromegaly

•Hemaglobinopathies

•Hereditary spherocytosis

•Neurofibromatosis

•Sturge–Weber

•Tuberous sclerosis

•Idiopathic (50%)

TOXIC RETINOPATHIES (1) 435

Toxic retinopathies (1)

A number of prescribed and nonprescribed drugs may cause retinal injury, usually via damage to the RPE layer. A high level of clinical suspicion may be required as these conditions are seen infrequently and use of the drug is often not volunteered.

Be alert to the possibility of toxicity when there is unusual pigmentary disturbance or crystal deposition. Withdrawal of the drug (coordinate with the prescribing physician; see Table 13.11) may lead to halting and even regression of the retinopathy; in some cases, however, it may continue to progress.

Chloroquine and hydroxychloroquine

These aminoquinolones are widely used as antimalarials and immunomodulators (e.g., in RA and SLE). Doses of >3.5 mg/kg/day for chloroquine and >6.5 mg/kg/day for hydroxychloroquine may result in retinopathy and maculopathy; risk increases with increasing dose, increasing duration, and reduced renal function.

Clinical features

• Asymptomatic, central/paracentral scotomas, dVA.

• Altered foveal reflex lirregular central macular pigmentation l depigmentation of surrounding zone (bull’s eye maculopathy), lendstage disease (generalized atrophy, RP-like peripheral pigmentation,

Table 13.11 Summary of recommendations to prescribing physician