A multicenter, prospective, randomized clinical trial to evaluate the relative merits of intravitreal injection of silicone oil or 20% SF-6/air mixture gas after vitrectomy in the treatment of complicated retinal detachment, i.e., proliferative vitreoretinopathy (PVR) is proposed. This document pertains only to the Coordinating Center for the study. The eleven Contributing Centers will all be self supporting. Each Contributing Center will provide to the Coordinating Center approximately 16 cases of PVR over 18 months of recruitment (total sample size = 176). Patients will be randomized to silicone oil or gas during the surgery. Follow-up is for two years post-operation. To evaluate the efficacy of the treatments, the rates of anatomical reattachment of the macula at six months post-operation (primary endpoint) will be compared between the two treatment groups. Additionally, the best corrected visual acuity (secondary endpoint), visual field improvement and complications will be monitored, compared, and reported. It is expected that the macular attachment rate for patients treated with silicone will be 1-1/2 times greater than that for patients treated with gas (power of the trial = 0.80).