It has been widely suggested that retinal ischemia induces a stimulus for neovascularization in such diseases as diabetic retinopathy, retrolental fibroplasia, and sickle retinopathy. The existence of this proposed angiogenesis factor has never been established. On-going research by investigators in this laboratory continues to suggest the existence of such an angiogenesis factor. The biologic activity in the cornea of an established neovascular stimulus, tumor angiogenesis factor, is also under pilot studies in this laboratory; the effect of tumor angiogenesis factor on developing and maturing retinal vessels has not yet been investigated. The proposed study will be directed toward the production of retinal neovascularization in laboratory animals by intraocular presentations of materials suspected of angiogenesis activity. These materials will include tumor angiogenesis factor as well as intraocular extracts from animals with retrolental fibroplasia. The long-term goal of these initial studies will include the identification and characterization of a human retinal angiogenesis factor; prevention and/or inhibition of such a factor to limit human retinal neovascularization would significantly reduce the ocular morbidity of diabetic retinopathy and other neovascular diseases.