CMV (cytomegalovirus) retinitis is the most common intraocular infection in patients with AIDS and is estimated to affect 35 percent to 40 percent of patients with AIDS. Untreated CMV (cytomegalovirus) retinitis is a progressive disorder, the end result of which is total retinal destruction and blindness. As of September 1997, drugs approved by the United States Food and Drug Administration (FDA) for the treatment of CMV (cytomegalovirus)retinitis were ganciclovir (Cytovene), foscarnet (Foscavir), and cidofovir (Vistide). Cidofovir has a prolonged duration of effect permitting intermittent administration. All systemically administered anti-CMV drugs are given in a similar fashion consisting of initial 2-week high-dose treatment (induction) to control the infection followed by long-term lower dose treatment (maintenance) to prevent relapse. Cidofovir is administered as an intravenous infusion once weekly for induction therapy and once every 2 weeks as maintenance therapy. The HPCRT evaluated the efficacy and safety of cidofovir therapy.