Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Toxoplasmosis

Toxoplasmosis

Background Usually represents a reactivation of healed early acquired/congenital toxoplasmosis and is less frequently a manifestation of acute recently acquired infection.

Symptoms Blurred vision, or floaters due to vitritis.

Signs

Toxoplasmosis

As inflammation subsides, the edges of active lesion harden off and are replaced by a chorioretinal scar with clearing of vitritis. Overall, 30% retain 6/12 vision or better. Discharge when the retinitis is quiescent. Advise patients that treatment cannot prevent recurrences (mean, 2.7 yr) and that they should return to casualty if symptoms recur.

Acute Retinal Necrosis

Background Acute retinal necrosis (ARN) is most frequently caused by varicella zoster virus (VZV) but is also reported with herpes simplex virus (HSV) I and II and rarely cytomegalovirus (CMV). Patients may be healthy or immunocompromized.

Symptoms Often there is no systemic disease although some may have evidence of recent or concurrent VZV or HSV infection. Onset is typically unilateral with visual loss, often with ocular or periocular discomfort. Sequential bilateral involvement occurs in up to one-third of cases, usually within 3 months, but may be delayed for several years. Patients may get recurrent anterior uveitis.

Signs Characterized by focal, well-demarcated, whitened areas of peripheral retinal necrosis outside the major vascular arcades (Fig. 8.16), which rapidly progress circumferentially to become confluent. Vascular occlusion, both arterial and venous, is an important clinical feature. Optic nerve head swelling is common. Vitritis is always present and may obscure the fundal view. There is a high incidence of retinal breaks just anterior to normal retina. Anterior uveitis is present in all patients, keratic precipitates may be large, and IOP is often elevated. Immuncompromised patients, particularly those with HIV infection, may have a more aggressive

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Acute retinal necrosis

form (previously called progressive outer retinal necrosis) but with less inflammation (p. 374).

Investigations Consider vitreous biopsy and VSV, HSV I & II, Epstein Barr, and CMV PCR in all patients to confirm the diagnosis. Request baseline FBC, U&E, and LFTs. If bilateral at presentation, inquire about sexual history/HIV risk and arrange testing as appropriate with infectious disease clinicians. Spontaneous VZV preceding ARN indicates immunocompromise until proved otherwise.

Differential diagnosis

■Behçet’s disease : features retinal necrosis and arterial and venous vasculitis, but also extraocular features.

■Pars planitis : may produce significant peripheral retinal whitening and vitritis but onset is not acute and ischaemia is absent.

■Syphilis : may cause retinal whitening, arteritis, and vitritis.

■Toxoplasmosis : can cause large peripheral white lesions and significant vitritis but typically there is a chorioretinal scar.

Treatment Early initiation of antiviral therapy is important. Admit for i.v. aciclovir 10 mg/kg infused over 1 hour t.d.s. for 1 week. Renal toxicity is the most important side effect; monitor U&Es and fluid balance, ensuring adequate intake (i.v. fluids if necessary) and output. As retinitis subsides, whitened necrotic retina is replaced by RPE scarring and atrophy. Systemic steroids (1 mg/kg and rapidly tapered) are usually introduced after 24 hours of i.v. aciclovir if significant vitritis limits the fundal view or there is optic nerve involvement. To prevent rhegmatogenous retinal detachment, some clinicians recommend prophylactic argon laser behind the posterior edge of involved retina (3 rows of

500 μm light/moderate burns) as soon as visualization is adequate. Others now feel that this is not helpful and have discontinued laser prophylaxis. If immunosuppressed, arrange physician review. I.V. aciclovir is followed by oral therapy (800 mg five times daily) for 6 weeks, aiming to stop any systemic steroids during this time. Some clinicians prescribe 12 weeks aciclovir since second eye involvement tends to occur in this interval. In immunosuppressed patients, the course of both i.v. and oral aciclovir may need to be prolonged. Avoid systemic steroids. Consider systemic or intravitreal foscarnet (2.4 mg in 0.1 mL) in severe cases, or those that relapse on aciclovir.

Cytomegalovirus Retinitis

Background Usually occurs in association with severe immunocompromise, either iatrogenic, from malignancy, or most commonly, AIDS (CD4+ count almost always < 50 cells/μL). In the majority, the cause of the underlying immunosuppression is already established, but CMV retinitis is the presenting feature in 2% of patients with AIDS.

Symptoms Visual loss or scotomas from posterior pole involvement. May be asymptomatic.

Signs Full-thickness necrotizing retinitis with haemorrhage, often with accompanying retinal vasculitis (Fig. 8.17). Slowly progressive (250–300 μm/week) and usually more rapid towards the retinal periphery than the posterior pole, so areas are characteristically sectorial. The edge of lesions are the most active, with expansion resembling a ‘brush-fire’. Visual loss occurs when retinitis involves the optic nerve or macula, or from rhegmatogenous retinal detachment, serous macular detachment, or cystoid macular oedema.

Differential diagnosis Small focal areas of involvement may be mistaken for cotton-wool spots of HIV retinopathy (these wax and wane, whereas CMV retinitis is progressive without

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Cytomegalovirus retinitis

treatment) or other herpes virus retinitis. HIV retinopathy is rare in black patients.

Investigations Inquire about sexual history/HIV risk and arrange testing as appropriate with an infectious disease clinician. Check VDRL (often positive). If the diagnosis is in doubt, arrange a vitreous biopsy PCR at the time of the first intravitreal injection.

Treatment Start treatment immediately and manage jointly with physicians. Drugs used for the treatment of CMV retinitis are virostatic and cannot prevent recurrence. Aim to induce remission with induction, then maintenance therapy while monitoring for relapse. Antivirals may be given locally either by intravitreal injection (ganciclovir, foscarnet) or implant (ganciclovir), or systemically either i.v. (ganciclovir, foscarnet, cidofovir) or orally (ganciclovir, valganciclovir).

Follow–up Watch for recurrence and second eye involvement. Within 1–2 week of induction expect a loss of retinal whitening and resolution of oedema, exudate, and haemorrhage, leaving retinal atrophy and RPE scarring. Reactivation may be more difficult to detect and may manifest as a smouldering border with a small area of retinal whitening, merely changes in the whiteness of the border, or a recurrence of perivascular sheathing. Serial photographs are invaluable.

Masquerade Syndromes

Background Masquerade syndromes are disorders which mimic intraocular inflammation but have an underlying cause which may be malignant, infective, or a miscellany of other causes. These include drug-induced, retained intraocular foreign body, Schwartz syndrome (rhegmatogenous retinal detachment and anterior chamber ‘cells’), ghost-cell glaucoma following vitreous haemorrhage, ocular ischaemic syndrome, and retinitis pigmentosa. Many are apparent from the history and examination, or due to their atypical clinical features, or failure to respond to steroids.

Lymphoma Always consider in patients over 60 years who present for the first with intraocular inflammation. Suspect if there is marked vitritis but good VA. Usually bilateral with both an anterior chamber reaction and vitritis (classically ‘veils’), sometimes with subretinal or intraretinal infiltration. The majority of patients have CNS non-Hodgkin’s lymphoma but there can be systemic spread, although this tends initially to produce choroidal disease. The eye may be the only organ involved. If suspected, arrange a vitreous biopsy for cytology, CNS imaging, and CSF cytology. Treatment comprises ocular and CNS irradiation and chemotherapy. Cystoid macular oedema is uncommon.

Leukaemia All forms of leukaemia may involve the eye. Manifestations include direct retinal and optic nerve infiltration, and serous retinal detachment overlying choroidal infiltrates. Subhyaloid haemorrhage, Roth spots, vascular dilatation or tortuosity, and cotton wool spots are secondary to thrombocytopenia and anaemia. Anterior segment involvement is less common but includes acute anterior uveitis with hypopyon (‘white eye’), diffuse iris infiltration, or iris nodules. If suspected, refer to a haematologist.

Retinoblastoma See page 407.

Melanoma Choroidal melanomas may cause signs of both anterior and posterior segment inflammation. Amelanotic choroidal tumours may simulate an inflammatory mass. Ultrasound and fluorescein angiography are useful in establishing the diagnosis. Iris tumours may be mistaken for inflammatory nodules. Diffuse iris melanomas may cause heterochromia.

Metastases Most commonly from lung and breast. Usually present as an isolated choroidal lesion which when flat may resemble an inflammatory focus but patients can present with endophthalmitis. Anterior segment metastases are rare but may cause an anterior uveitis, pseudohypopyon, or iris nodules.

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Uveitis in children

Uveitis in Children

Background Most types of uveitis can be seen in children and are managed in a similar way to adults depending on the anatomic location, severity, threat to vision, and complications present. For example, children may get recurrent acute anterior uveitis associated with HLA-B27 and diseases such as ankylosing spondylitis. Although uncommon, Fuchs’ heterochromic cyclitis has been reported even in young children. Children may get sympathetic ophthalmia following trauma and disorders such as Vogt-Koyanagi-Harada syndrome. Infective disorders such as chickenpox can cause a uveitis, and metastatic endophthalmitis can occur from any septic site. Reactivation of toxoplasmic retinochoroiditis is uncommon in children, and the commonest cause of posterior uveitis in the under 16 age group is pars planitis.

Juvenile idiopathic arthritis is associated with uveitis that may be asymptomatic, so review all children at diagnosis. The risk of uveitis depends on the type of arthritis (systemic versus polyarticular versus pauciarticular). Uveitis in systemic disease is rare. ANA+ve pauciarticular females aged <7 years are at highest risk. Review high-risk children (those aged <7 years who are

ANA+ve, with paucior polyarticular arthritis) 3 monthly, mediumrisk 6 monthly, and low-risk (systemic disease) yearly. The highrisk group become medium-risk after 4 years follow-up. The medium-risk group becomes low-risk after 4 years. All go to lowrisk after 7 years. The characteristic chronic anterior uveitis has a high ocular morbidity if not well controlled; band keratopathy, posterior synechiae, cataract, cyclitic membranes, and macular oedema can all occur. Posterior synechiae at presentation indicate severe disease. Topical steroids and mydriatics are the mainstay of treatment in children with anterior uveitis. Steroid response may occur in addition to open angle glaucoma and raised IOP secondary to pupillary occlusion. Usually, cataract removal is by lensectomy because of cyclitic membrane formation; systemic steroid cover for this is helpful.