Patients assigned to immediate treatment underwent surgery to implant the ganciclovir device within 48 hours of enrollment and baseline photographs. Postoperatively, patients were evaluated the next day, weekly for 2 weeks, and then every 2 weeks until progression of CMV retinitis occurred. At each examination, in both eyes, visual acuity with current correction and best correction was determined using Early Treatment Diabetic Retinopathy Study eye charts; intraocular pressure was determined; evidence of inflammation or cataract was evaluated; and all retinal findings were documented. Any adverse event considered even possibly related to the device or to the implantation procedure was documented. Standardized nine-field fundus photographs were taken at each 2-week visit. The ganciclovir implant was exchanged at 32 weeks or earlier if progression of CMV retinitis occurred.