Vasodilation and the etiology of diabetic retinopathy: a new model.

The evidence in support of the theory that retinal vascular stretching leads to leakage, formation of microaneurysms, and neovascularization is reviewed. The efficacy of photocoagulation and vitrectomy in controlling retinal microangiopathy accompanying diabetes is shown to depend upon reduction of the vascular dilatation. It is possible that the vascular dilatation in diabetes results from high blood glucose levels increasing oxygen consumption in the inner retina, with a resulting vascular dilatation to supply increased oxygen to the retina. This retinal vascular dilatation is the initial cause of the vascular pathology in diabetes.