[Retinal ischemic changes in diabetic rats treated with pancreatic islet transplantation beneath the renal capsule]

The effect of pancreatic islet transplantation beneath the renal capsule on retinal and choroidal structure was studied using Lewis rats. Rats were divided into 3 groups: an untreated diabetic group induced by intravenous injection of streptozotocin 65 mg/kg; an islet transplanted group 1 month after induction of diabetic state; and an untreated control group. Whole retinochoroidal units were examined by light and electron-microscopy. In 6 out of 9 cases in the transplanted group, the retina showed marked destructive changes in the outer layer including pigment epithelial cells and vacuolization of the inner layer 6 months after islet transplantation. Occlusion and fibrosis of the choriocapillaris adjoining the degenerated retina were also observed. Such changes were not observed in the other groups. On electron microscopy, occlusion of capillaries and destruction of endothelial cells were frequently found in the degenerated retina. These retinal ischemic lesions appear to be caused by microvascular obstruction.