This protocol is designed for the screening of patients with either diagnosed or undiagnosed retinovascular diseases. It serves as a first step for individuals who may be eligible and wish to participate in National Eye Institute clinical research studies of retinovascular diseases. Each individual will be thoroughly evaluated during the screening process to determine if they are suitable candidates for inclusion in any of the National Eye Institute"s ongoing studies. The screening evaluation will include past and current medical histories and an appropriate physical examination, namely a comprehensive eye exam. Other routine diagnostic procedures and tests may also be completed in order to help determine a subject's eligibility. These tests and procedures are of minimal risk as they are part of standard medical practice. No experimental diagnostic or therapeutic procedures will be performed. Once the screening process is completed and their eligibility is assessed, the subjects will be informed of their options to participate in one or more of the current clinical research studies. If no appropriate protocol is identified, recommendations for other treatment options may be given to the individual, their primary doctor, or referring physician.