The diagnosis of cytomegalovirus retinitis.

Immunosuppressed patients are at risk for developing cytomegalovirus retinitis. This disorder is the most common cause of vision loss in patients with the acquired immunodeficiency syndrome (AIDS). Cytomegalovirus retinitis is probably the result of hematogenous spread of the virus to the retina after systemic reactivation of a latent cytomegalovirus infection. Although the ophthalmic infection may initially be asymptomatic, the retinal necrosis it produces may result in both loss of visual field and decreased visual acuity. Routine screening of these patients is required for early diagnosis. The retinitis is detected with ophthalmoscopy as either a perivascular yellow-white retinal lesion frequently associated with retinal hemorrhage or as a focal white granular infiltrate, often without hemorrhage. Both lesions enlarge in a progressively expanding "brushfire" pattern. The diagnosis of cytomegalovirus retinitis, as well as the evaluation of its response to therapy, is determined primarily by clinical criteria. Serial retinal photography is an objective method to assess the changing appearance of these lesions. Ganciclovir and foscarnet are investigational antiviral drugs that appear to be effective in treating cytomegalovirus retinitis. However, maintenance therapy with these medications is required after initial treatment because the disease often relapses. The combined expertise of the internist and the ophthalmologist is needed to diagnose and treat these patients.