During the third and final year of this grant, we shall continue our dynamic recording system for ocular fluorescein angiography which will hopefully permit clinical measurement of vascular caliber changes and blood flow in patients with a variety of ocular, cerebral, and systemic diseases. Examples are many and include: a) the analysis of rapid caliber changes which occur after the administration of certain drugs, b) the detection of early small functional alterations in blood flow before the morphologic changes of "late disease" appear, and c) the study of flow rates in diabetic retinopathy (and other fundus diseases) before and after photocoagulation, to shed light on the mechanisms of effective therapy. Specifically, during the third year the majority of patients undergoing fluorescein angiography at the Retina Offices of Albany Medical College will have their angiograms recorded using our televised recording system. This continued clinical trial at all stages of instrument development will assure the systems clinical usefulness throughout the trial period. The flash system which will eliminate picture blur due to eye movement artifact will be perfected. The automatic fluorescein injection system will be finally integrated into the recording system for purposes of standardization of injection speeds. The stereoscopic recording and viewing will be further explored in order to determine how important that is in the clinical diagnosis of vascular diseases of the fundus. The initial vascular caliber and flow studies will be done as a preliminary pilot study. If reliable information about vascular caliber changes and speed of flow can be obtained using this system, this will form the basis of a continuation grant to be applied for during l974. Thus, our present grant involves instrument development and will hopefully lead to another grant involving instrument usage in fundus disease.