Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Best’s Disease

Background Autosomal dominant macular dystrophy due to mutations in the UMOZ gene.

Symptoms May be asymptomatic or present in childhood or teens with poor central acuity.

Signs The macula may appear normal or show variable, evolving vitelliform changes described as egg-yolk, scrambled egg, pseudohypopyon, and then atrophy (Fig. 10.49). Choroidal neovascularization sometimes occurs.

History and examination Examine family members and draw a family pedigree (p. 412). Inheritance has variable penetrance, so affected relatives may be asymptomatic and have subtle signs, although the electro-oculogram (EOG) abnormality is seen in all those with the mutant gene.

Differential diagnosis Consider central serous retinopathy, pigment epithelial detachment, toxoplasma, and other causes of macular atrophy (p. 448).

Investigations Reduced light-induced rise of the EOG is diagnostic. Fluorescein angiography shows hypofluorescence initially (blockage from vitelliform material), and hyperfluorescence if RPE atrophy occurs. Testing for the affected Bestrophin gene is

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Best’s disease

now possible. Consider fundus autofluorescence if available. This shows decreased signal from the pale material.

Management Offer genetic counselling with a senior clinician and annual review. No treatment exists at present.

Pattern Dystrophy

Background An autosomal dominant macular disease.

Symptoms May have paracentral distortion, loss of VA or may be asymptomatic.

Signs The macula may show a pale subretinal or pigmented deposit at the fovea or in a linear distribution (Fig. 10.50). With time, central atrophy may occur. Choroidal neovascularization is rare.

History and examination Examine family members and draw a family pedigree (p. 412). Although autosomal dominant, there is variable expression and incomplete penetrance, so affected relatives may be asymptomatic and signs subtle.

Differential diagnosis Consider central serous retinopathy, Best’s disease and age-related macular degeneration.

Investigations Autofluorescence imaging (if available) is helpful and shows hyper-autofluorescence of the fundal lesions. Genetic testing is possible (RDS gene).

Management Offer genetic counselling with a senior clinician and annual review. No treatment exists at present.

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Stargardt’s disease

Stargardt’s Disease

Background A common autosomal recessive (AR) disease with yellow RPE flecks (fundus flavimaculatus) plus macular atrophy due to mutations in the ABCA4 gene. The carrier rate is high so children may be affected (pseudo-dominance).

Symptoms Poor central vision in childhood or teens is most common, but patients may present later in life.

Signs May be normal initially, but the macula develops ‘beatenbronze’ appearance or expanding atrophy, surrounded by yellow flecks. ‘Salt-and-pepper’ peripheral pigmentation may occur later (Fig. 10.51).

Differential diagnosis Exclude other causes of macular atrophy (p. 448), especially cone dystrophy. The yellow flecks have a more patterned appearance than drusen. Unlike

retinitis punctata albescens, the visual field, vessels, and discs are minimally affected. Fundus albipunctatus is an AR disease with nyctalopia and smaller white dots throughout the fundus. VA is normal.

Investigations The pattern electroretinogram (PERG) is abnormal in all cases, the full field ERG is abnormal in 15%, and the electro-oculogram in 2.5%. Fluorescein angiography classically shows a dark choroid with hyperfluorescent flecks, but not always. Fundus autofluorescence helps quantify

RPE damage. The yellow flecks are hyper-autofluorescent. Genetic testing is possible but not widely available.

Management Offer counselling with senior staff, blind or partial sight registration, low-vision aids, and annual review. There is no treatment.

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North carolina macular dystrophy

North Carolina Macular Dystrophy

Background An autosomal dominant macular dystrophy with variable expressivity. The gene locus is known.

Symptoms May be asymptomatic or present in childhood with poor central acuity.

Signs The macula characteristically shows well-defined atrophy centred on the fovea with hyperpigmented edges, often with remarkably good VA (Fig. 10.52). In some patients changes are limited to fine, densely packed, drusen-like deposits in the central 3 degrees.

History and examination Examine family members and draw a family pedigree (p. 412). Although autosomal dominant, affected relatives may be asymptomatic and signs subtle.

Differential diagnosis Consider macular dystrophies with atrophy.

Investigations Colour photography.

Management Offer genetic counselling with a senior clinician, annual review, and low-vision aids. No treatment exists at present.

Albinism

Background A genetic disorder of melanin production.

Classification

■Ocular.

■Oculocutaneous.

1.Tyrosinase-negative.

2.Tyrosinase-positive.

■Albinoidism.

Symptoms Photophobia and blurred vision.

Signs Although highly variable, signs are generally most severe in tyrosinase-negative individuals, intermediate in tyrosinasepositive and ocular cases, and mildest in albinoidism. Features include VA loss, nystagmus, strabismus, refractive errors, iris transillumination, pale fundus, foveal and optic nerve hypoplasia, and misrouting of fibres in the optic chiasm. Skin pigmentation is variable in ocular albinism.

History and examination Draw a family tree (p. 412) and examine family members. Ocular albinism is commonly X-linked but sometimes autosomal recessive. Female carriers may show mild iris and characteristic fundus changes (Fig. 10.53). Oculocutaneous cases are usually autosomal recessive. In tyrosinase-positive patients ask about recurrent infections (Chediak-Higashi syndrome) and bleeding/bruising problems (Hermanski-Pudlak syndrome).

Investigations Consider electrophysiology (p. 428), neuroimaging, tyrosinase testing, FBC, and coagulation. Prenatal (intrauterine) testing is possible.

Management Arrange genetic counselling with an experienced clinician, and low-vision aids if required. Albinos have an increased risk of basal and squamous cell carcinomas, so refer to dermatology if suspected. Refer patients with immunocompromise or bleeding diathesis to haematology.

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Syphilis

Background A sexually transmitted infection caused by the spirochaete Treponema pallidum. Mother-to-child transmission can also result in congenital infection.

Classification and systemic features

■Primary : genital ulcer (chancre).

■Secondary : lymphadenopathy, rash, mucous membrane lesions, meningitis.

■Latent: no clinical manifestation. May last for many years.

■Tertiary : cardiovascular disease (aortitis, aortic regurgitation, angina), neurosyphilis (myelopathy, mental changes), systemic gummata (fibrous deposits).

Signs Ocular disease may occur at any stage. Primary infection may rarely present with a chancre on the eyelid. Signs of secondary and tertiary infection include oculomotor palsies, madarosis (loss of eyelashes), conjunctivitis, interstitial keratitis, episcleritis, scleritis, glaucoma, Argyll Robertson pupil (light-near dissociation), field loss, uveitis, chorioretinitis, choroidal ischaemia, periarteritis, neuroretinitis, and optic neuritis. Late changes may mimic retinitis pigmentosa with paravascular retinal pigment, vascular attenuation, and pale discs. Congenital syphilis classically produces interstitial keratitis and pigmentary retinopathy.

Investigations

■VDRL: this measures antiphospolipid antibody levels and is not specific to syphilis. Never use VDRL as the sole screening test as false positives occur in a variety of conditions including connective tissue diseases and pregnancy. VDRL is valuable for monitoring treatment as the titres are high in active disease and fall with effective therapy.

■FTA-ABS, MHA-TP or TPHA : these tests all measure specific antitreponemal antibody levels and in most patients they remain positive for life, even after effective therapy. Other treponemes (including yaws) give positive results, as occasionally do other spirochaetes (Lyme disease).

Management Refer to an infectious disease consultant for systemic treatment (often high-dose penicillin). In many countries, syphilis is a notifiable disease. In at-risk individuals, consider referral for HIV testing, as this may coexist. Topical steroids may be required for ocular inflammation. Only consider systemic steroids after full investigation and treatment of any underlying infection.

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Solar retinopathy

Solar Retinopathy

Background Foveal phototoxicity secondary to sun-gazing.

History Ask about predisposing factors, such as recreational drug use, mydriatic or photosensitizing medications, e.g. tetracycline, use of condensing lenses, e.g. telescopes, and viewing a solar eclipse.

Symptoms Blurred vision, scotoma, chromatopsia, metamorphopsia and afterimage.

Signs VA is usually 6/12 to 1/60 acutely with reduced near acuity and Amsler grid changes. Fundoscopy reveals a unior bilateral yellowish foveal lesion, sometimes with a grey annulus (Fig. 10.54). This fades over a week, leaving a small, welldefined, deep red spot which persists for life, or rarely mild RPE changes. Recovery of VA is usual. A national UK survey following a solar eclipse suggested most cases resolve.

Differential diagnosis Consider Best’s disease, cone dystrophy; light-damage from an operating microscope, central serous retinopathy, age-related macular degeneration, and toxic retinopathy. For other causes of macular atrophy see page 448.

Investigations Fluorescein angiography is often normal.

Treatment Systemic steroids and antioxidants (ginko glycosides) have been used, but the evidence is not clear.