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Chorioretinitis

DESCRIPTION: A type of posterior uveitis, almost always affecting the retina; usually follows an active microbial invasion of the tissues by a causative organism which is rarely recovered (definite etiological diagnosis is seldom possible); generally classified as granulomatous. The onset may be in utero when caused by the Toxoplasma gondii, probably the most common cause (see Toxoplasmosis). If granulomatous uveitis is acquired, the onset is insidious: vision gradually becomes blurred, pain is minimal, mild photophobia is present, and the pupil is often constricted and/or irregular in shape. Fresh lesions seen through the ophthalmoscope appear as yellowish-white patches through a hazy vitreous. As healing occurs, the vitreous clears and pigmentation appears at the edges of the lesions. In the healed stage, there is considerable pigmentation (i.e., "scars") and scotomas occur where the lesions are located; these healed areas usually do not result in significant visual loss. If the macula has not been involved, recovery of central vision is complete. The disease can last months to years, sometimes with remissions and exacerbations, and is capable of causing permanent damage with marked visual loss.

TREATMENT: Must be treated medically, usually with anti-infective agents and systemic corticosteroids. Although organisms responsible for toxoplasmosis and tuberculosis (both possible causes of chorioretinitis) may be activated by corticosteroids, they are given as a calculated risk to control the inflammatory response when vision is threatened.

IMPLICATIONS: Functional vision depends on the extent and site(s) of the healed lesions. If the macular area was not involved, central acuity remains normal and the scotomas are usually not significant in terms of visual functioning. However, if the macula was involved, the lowered acuity can result in markedly reduced visual functioning. magnification may be helpful.

 

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