Detection of CMV (cytomegalovirus) retinitis and other infectious retinopathies early in the course of the opportunistic infection is essential for the prevention of blindness in AIDS patients. CMV retinitis is an opportunistic infection that afflicts HIV-infected patients who are immunodepressed, usually after the patient's CD4 count drops below 50. CMV is one of the most common opportunistic infections that afflicts HIV positive people, and 85% of the time it first presents in the retina. When left untreated, CMV can rapidly destroy the retina, Causing total blindness, and involvement of the fellow eye is Common. In addition to blindness, there are frequently further complications such as an elevated risk of retinal detachment, requiring further surgery and the resulting potential negative impact on vision. Furthermore many people who are HIV positive, especially in the minority and underserved communities, often do not receive proper ophthalmological care, and remain undiagnosed with CMV retinitis until it impacts upon the central 10 degrees of the visual field. Therefore, it is critical to design a rapid, inexpensive, and sensitive screening test which can be implemented by primary care physicians to screen large numbers of patients in the primary care setting. We have three specific aims for this study: (l).We have published a study which shows that in the laboratory, entoptic perimetry has a 95% sensitivity and 95% specificity in detecting lesions due to CMV retinitis within the central 30 degrees radius of vision. We will develop a reliable, optimized version of 60 degree entoptic perimetry that has a high sensitivity and specificity in detecting mid-peripheral CMV retinitis in HIV- positive, visually asymptomatic individuals during Year One and the first half of Year Two. (2) After completion of Specific Aim l, we will implement optimized entoptic perimetry as a screening test for CMV retinitis, to be administered by primary care providers and ancillary personnel in the primary care setting where ophthalmological services are not readily available. Entoptic perimetry will be a highly sensitive and specific non-invasive screening test that will allow detection of central and mid-peripheral CMV retinitis prior to development of vision-threatening CMV disease. (3) Finally, during Years 4 and 5, we will implement optimized entoptic perimetry as a screening test for reactivations of CMV retinitis in patients previously diagnosed with the disease. This will allow patients to self-monitor progression of CMV retinitis in their homes.