Corneal endothelial cells in man decrease in numbers with age and are not replaced following injury. If the injury is severe, or if subsequent stress occurs, corneal edema and loss of transparency may occur. Recent studies of corneal endothelial regeneration in many species in our laboratories have shown that the endothelium of cat reacts to injury in a fashion most similar to that of man. Cat will therefore be used as a model in subsequent studies. The primary objectives are: 1) To compare the effects of drugs, irrigating solutions, inflammation, and increased intraocular pressure on the ultrastructure and function of regenerated and normal endothelium of cat cornea; 2) to determine the effects of Vitamin A, thyroid hormones, and insulin on endothelial regeneration; and 3) to characterize the metabolic changes in regenerated and cultued endothelium. Transcorneal freezing will be used to destroy the central endothelial cells. Biomicroscopy, pachometry, and clinical specular microscopy will be used to follow the clinical course of endothelial regeneration. The endothelium will be examined by scanning and transmission electron microscopy. Autoradiography will be used to assess the incorporation of tritiated thymidine into nuclear DNA. Radiothyroidectomy will be used to produce insulin deficiency. Alterations in glucose metabolism will be determined by measuring glucose utilization, lactate production, and hexose monophosphate shunt activity.