Retinopathy in diabetic hypertensive monkeys: a pathologic study

Abstract• Background: No satisfactory primate model of diabetic retinopathy has been produced. The clinical picture of microangiopathic retinopathy in diabetic hypertensive monkeys has been previously reported. The present study describes the pathologic findings of these animals. • Methods: Eleven eyes of six monkeys (five rhesus, one cynomolgus) were studied. Diabetes mellitus was either spontaneous or induced by streptozocin; mild arterial hypertension was either spontaneous or induced by fludrocortisone acetate. In two monkeys, the horseradish peroxidase tracer technique was employed. Trypsin flat preparations of the nasal retinal vasculature were prepared. The material was studied by light and electron microscopy. • Results: We divided the development of the microangiopathic retinopathy into three stages. In the early stage, background retinopathy was characterized by microvascular abnormalities and capillary dropout. Massive vascular leakage, intraretinal exudates and hemorrhage, cystoid degeneration, and cotton-wool spots were features of an exudative retinopathy in the second stage. In the final stage, chronic ischemic retinopathy was characterized by vascular occlusions and areas of retinal atrophy. • Conclusion: Microangiopathic retinopathy in diabetic monkeys with mild hypertension presented many features of human diabetic and hypertensive retinopathy, except vitreous neovascularization.