CMV retinitis is the most common intraocular infection in patients with AIDS and is estimated to affect 35 to 40 percent of patients with AIDS. Untreated CMV retinitis is a progressive disorder, the end result of which is total retinal destruction and blindness. The first two drugs approved by the United States Food and Drug Administration (FDA) for the treatment of CMV retinitis were ganciclovir (Cytovene) and foscarnet (Foscavir). At the time of this trial, both ganciclovir and foscarnet were available only as intravenous formulations. Both drugs were given in a similar two-step fashion: an initial 2-week course of high-dose therapy (induction) to control the infection followed by long-term lower dose therapy to prevent relapse (maintenance). The FGCRT compared foscarnet and ganciclovir as initial therapy for CMV retinitis.