The objectives of this study involve four problems related to intravitreal surgery: 1. Establishment of an effective means of prevention and treatment of intraocular infection. 2. Establishment of the feasibility of coagulation of intravitreal neovascularization with a radiofrequency probe, including a comparison of its efficacy to that of the argon laser currently used in occlusion of intravitreal neovascularization. 3. Establishment of the feasibility of vitrectomy with emphasis on the best time to perform such surgery, i.e., the early or late stage of vitreous hemorrhage. Establishment of the use of vitrectomy in tractional detachment of the retina. Objectives 1, 2, and 3 have been completed in the past two years and Objective 4 remains as a goal for the coming year.