Inflammatory Retinal Diseases

Intraocular inflammatory disorders encompass a broad spectrum of diseases that are a major cause of severe visual impairment.¹ They may be specific to the eye (e.g. punctate inner choroidopathy) or be part of a systemic problem (e.g. acute retinal necrosis due to herpes simplex infection) or a combination of both (e.g. cytomegalovirus retinitis in AIDS). There is frequently a blurring of distinction between these categories.

Related articles

• Many retinal inflammatory conditions occur in association with choroidal inflammation - chorioretinitis. Please refer to our dedicated article on chorioretinal inflammation for more detail about these conditions.
• Our article on other choroid disorders further describes the group of inflammatory conditions collectively known as the idiopathic multifocal white dot syndromes and there is a dedicated article on birdshot chorioretinopathy.
• Retinitis also occurs in Behcet's disease - see our dedicated article.

This article outlines the variety of other conditions which cause retinal inflammation.

Parasitic infections

Ocular toxoplasmosis²

• Description - infection with the intracellular protozoan Toxoplasma gondii is the most frequent cause of infectious retinitis in immunocompetent individuals. Presentation is usually following reactivation of a prenatal infestation. It can cause a variety of types of retinitis, the end point of which is scarring. Depending on where in the fundus the scarring is, vision may or may not be significantly impaired. Active disease is usually associated with anterior uveitis.
• Presentation³ - often between 10 and 35 years of age: painless blurred vision and floaters ± symptoms and signs of anterior uveitis. AIDS patients often experience pain with marked anterior segment involvement.
• Management - treatment aims to reduce the risk of permanent visual impairment (by reducing the size of the retinochoroidal scar), the risk of recurrence and the severity and duration of acute symptoms.⁴ Patients considered for treatment include immunocompromised patients, pregnant women and patients who have lesions that are deemed to be in key positions on the retina or have reached a certain size. Treatment will include topical steroid drops (not an injection), antitoxoplasmic agents (sulfadiazine, clindamycin, pyrimethamine, atovaquone, azithromycin), adjunct systemic corticosteroids in the immunocompetent patients and topical cycloplegic agents if there is concurrent anterior chamber inflammation.
• Outcome - this is a self-limiting infection in an immunocompetent patient with mild, peripheral disease. Outcome ultimately depends on the location of the scars.

Ocular toxocariasis⁵

• Description - accidental ingestion of dog roundworm (Toxocara canis) or the cat roundworm (Toxocara cati) gives rise to toxocariasis which can affect the liver, lungs, muscles, eyes and brain. The eye tends to be affected in older children and in young adults where the larvae migrate to the posterior segment of the eye. When the larvae die, they disintegrate and cause an inflammatory reaction followed by granulation which is when the patient presents.² There are three clinical pictures:
  • Chronic endophthalmitis (usually presenting between two and nine years old)
  • Posterior pole granuloma (patients aged between six and 14 years old)
  • Peripheral granuloma (adolescence to adulthood)
• Presentation - otherwise healthy child who may have a history of ingesting dirt or owning a puppy. Unilateral presentation with one of decreased vision, red eye or leukocoria ± strabismus.
• Management - steroids and occasionally surgery for the endophthalmitis. Surgery for the other two forms should complications arise (e.g. retinal detachment).
• Outcome - generally good.

Diffuse unilateral subacute neuroretinitis⁶

• Description - this is a progressive disease of the retina which is thought to come about as a result of an inflammatory reaction to the excretory products of larvae (the exact pathogens are not always known). Despite its name, it is not always unilateral.
• Presentation - men are more commonly affected than women, presenting in their 20s and 30s with visual loss (mild initially, then becoming severe), scotoma, floaters and an uncomfortable red eye. In addition to optic disc swelling, a vasculitis and a vitritis, nematodes can be seen on examination.
• Management - laser photocoagulation of the nematodes and antihelminthic treatment. Surgery is occasionally required.
• Outcome - good prognosis when identified early.

Viral infections: acute retinal necrosis²

• Description - common viruses such as herpes simplex and varicella zoster may occasionally give rise to retinitis as can the cytomegalovirus (CMV). However, this often occurs in the context of immunocompromised patients (e.g. AIDS patients) and is dealt with separately below. The exception is the rare condition of acute retinal necrosis. Congenital rubella also affects the retina in the form of a visually insignificant pigmentary disturbance (visual problems in these cases occur due to anterior segment abnormalities).
• Presentation - acute retinal necrosis (ARN) occurs due to herpes simplex 2, under the age of 15 and to herpes simplex 1 or varicella zoster virus later on in life. The presentation may be insidious (painless decrease in visual impairment) or acute (painful, rapid decrease in vision) in otherwise healthy patients (male: female = 2:1).
• Management - antivirals followed by systemic steroids and aspirin. Laser treatment and surgery may also be necessary.
• Outcome - the acute phase resolves within about 12 weeks but leaves scars behind - depending on where these are on the retina, vision is more or less affected. Without treatment, the second eye becomes involved in 65% of patients and the overall visual prognosis is guarded. Many complications may occur.

Fungal infections

• Description - Histoplasma capsulatum may cause visual problems relating to an exudative maculopathy (see our article on macular oedema). Note that there is a related disease entity called presumed ocular histoplasmosis syndrome (POHS) in which there is a clinical picture similar to histoplasmosis but with no evidence of H.capsulatum. This condition is associated with HLA B7 and HLA-DR-W2 positivity.⁷ Candida albicans infections tend to occur in immunocompromised patients, intravenous drug addicts and in patients with long-term indwelling catheters.² This pathogen gives rise to multifocal retinitis in addition to choroiditis and cotton-ball lesions floating in the vitreous. Cryptococcus neoformans rarely affects the eyes, tending to occur in the central nervous system of AIDS patients.
• Presentation
  • Histoplasmosis - asymptomatic unless macula involved
  • Candidiasis - progressive unilateral blurring of vision
  • Cryptococcus infection - progressive decrease in visual acuity if lesions threaten macula
• Management - histoplasmosis is treated only if there is macular neovascularisation (laser photocoagulation). Antifungals (± surgical intervention e.g. vitrectomy) are used in the other fungal infections.
• Outcome - this depends on speed of diagnosis and site of lesion. Macular or optic nerve head involvement carry a poor prognosis, as do complications e.g. retinal detachment and retinal necrosis.

Mycobacterial infections

• Tuberculosis - uveitis and retinitis secondary to tuberculosis is rare in developed countries and is usually a diagnosis suspected based on history and after unsuccessful treatment of a prolonged uveitis. Diagnosis is ultimately serological and treatment is with antituberculous drugs.
• Leprosy - this tends to preferentially affect the anterior segments of the eye, causing iritis, trichiasis, keratitis and scleritis.

Spirochaetal infections

• Syphilis - ocular syphilis is uncommon and tends to occur during the secondary and tertiary stages of the disease.² Various parts of the globe may be affected (uvea, choroid, retina or optic nerve head). Neuroretinitis results in disc oedema, haemorrhages and eventually, optic atrophy. Neurosyphilis needs to be ruled out (by lumbar puncture) and it is treated with high dose penicillins (or tetracycline in penicillin-allergic patients).
• Lyme disease - neuroretinitis is one of the many ophthalmological pictures that can arise from infection with Borrelia burgdorferi. Treatment is with doxycycline.

Retinal disease in HIV-infected patients

• Description - CMV retinitis is the most common ocular infection in AIDS (34% prevalence³) and rarely may be the first manifestation of this disease.² The second most common opportunistic infection is caused by an aggressive variant of the varicella zoster which causes progressive outer retinal necrosis (PORN). Other pathogens commonly found in this patient group are Toxoplasma gondii, Pneumocystis carinii and Treponema pallidum (causing syphilis). Non-infectious retinal microvasculopathy ('HIV retinopathy') also affects 50-70% of these patients.³
• Presentation - depending on the condition, asymptomatic (HIV retinopathy) to a rapidly progressive bilateral visual loss (PORN). The infective retinitis patients present with a similar, but often more severe, picture than non-AIDS patients:
  • CMV retinitis - scotoma / decreased vision in one / both eyes ± floaters
  • PORN - rapid, progressive visual loss
  • Toxoplasmosis - see above
  • Pneumocystis carinii - mild decrease in visual acuity (may be asymptomatic)
  • Syphilis - may mimic CMV retinitis in appearance and presentation
• Management - antibiotics or antivirals appropriate to the infecting pathogen. Treatment will be intravenous. Patients treated for syphilis will also typically be treated for chlamydial infections too. There is no specific treatment for HIV retinitis.
• Outcome - variable depending on problem (see above).

Sympathetic ophthalmia

• Description⁸ - this is a rare, autoimmune, granulomatous uveitis that occurs in both eyes following penetrating trauma (including surgery) to one eye. The exact pathophysiology is unknown but it is thought to be a sensitivity to the uveal pigment.
• Presentation³ - bilateral eye pain, decreased vision (near affected before distance) and a history of penetrating injury (usually 4-8 weeks previously but this ranges from days to years).
• Management - this is managed with steroids but may be prevented (or even managed) by enucleation of the fellow (traumatised) eye if this is blind. Immunosuppressive agents may be required.⁸
• Outcome - unless this is treated early and aggressively, the visual outcome is poor.

Vogt-Koyanagi-Harada syndrome⁹

• Description² - this is an idiopathic multi-system disease most often occurring in Hispanics, Japanese and pigmented patients. Skin changes and anterior uveitis predominate in one sub-group of patients whereas neurological features and retinal inflammation and detachment predominate in another. It is associated with, among others, HLA-DR4 and Dw15.
• Presentation³ - red eyes, decreased vision, photophobia and pain associated with a headache, stiff neck, nausea and vomiting, fever and malaise. There may also be hearing loss, dysacousia and tinnitus.
• Management - steroids (systemic in severe disease) ± immunosuppressing agents.
• Outcome - this tends to be poor. Early and aggressive treatment may improve the situation but the associated retinal detachments, cataracts and glaucoma can occur, making the prognosis very guarded.

Acute retinal pigment epitheliitis

This is a rare idiopathic inflammatory condition primarily affecting the retina in the macular area. It tends to be unilateral. There is no treatment but the prognosis is excellent.

Sarcoidosis-related retinitis

This multi-system, idiopathic, granulomatous disease can cause anterior, intermediate or posterior uveitis. Retinal granulomas in the absence of other ocular involvement is possible but uncommon.