Ocular lesions in leptin receptor-deficient medaka were examined histopathologically at 10, 28, and 37 weeks post hatching. Leptin receptor-deficient medaka at 28 and 37 weeks old showed hyperglycemia and hypoinsulinemia. Histopathologically, vacuolation, swelling, fragmentation, and liquefaction of the lens fibers and dilatation of the retinal central veins, retinal capillaries, iridal veins and capillaries, and choroidal veins were observed in leptin receptor-deficient medaka at 28 and 37 weeks old. Thinning of the total retina, pigment epithelial layer, layer of rods and cones, outer granular layer, outer plexiform layer, inner granular layer, and inner plexiform layer was observed in leptin receptor-deficient medaka at 28 and 37 weeks compared with in control medaka. These histopathological characteristics in leptin receptor-deficient medaka are similar to characteristics in ocular lesions of rodent models for type II diabetes mellitus, making leptin receptor-deficient medaka a useful model of diabetic cataract and retinopathy.
Keywords: cataract; hyperglycemia; leptin receptor-deficient medaka; retinopathy; vascular dilatation.