Cytomegalovirus (CMV) is among the most frequently encountered opportunistic infections in patients with AIDS. In the era of prophylaxis for pneumocystic pneumonia, CMV disease is estimated to affect 45 percent of patients with AIDS sometime between the diagnosis of AIDS and death. Retinitis has been estimated to account for up to 85 percent of CMV disease in these patients, making CMV retinitis the most common ocular infection encountered. CMV retinitis is a relatively late-stage manifestation, associated with cluster of differentiation 4 (CD4) + T-cell counts < 100 cells/µL and often < 50 cells/µL.