Diabetic retinopathy and choroidal angiopathy in diabetic rats (WBN/Kob)

Retinopathy and choroidal angiopathy were both detected in aged male rats of the WBN/Kob strain with sustained diabetes. Hyperglycemia and glucosuria were found starting from 12 months of age and lasted through 24 months of age. Macroscopically, the vitreous body was partially or entirely replaced by white mass in 3 of 9 diabetic males. Histopathologically, the intravitreal white mass consisted of collagen fibers accompanied by numbers of newly formed vessels. Intraretinal angiopathy was accompanied with newly formed vessels, which were observed within the retina in 5 of 9 diabetic males, and marked hyalinization of intraretinal vessels was detected in 6 of 9 males irrespective of the presence of intravitreal neovascularization. Furthermore, hyperglycemia-related choroidal angiopathy was also seen with newly formed blood vessels originating from the choroid penetrating the retinal pigment epithelial layer and invading the retina in 8 of 9 diabetic males. Focal proliferation or degeneration of the pigment epithelial cells was associated in the region with choroidal angiopathy. In females, choroidal vessels slightly raised the pigment epithelial layer; however, they were localized in the choroid. The present study indicates that the WBN/Kob strain of rats is a useful model for both diabetic retinopathy and diabetic choroidal angiopathy.