Vascular endothelial growth factor gene regulation and action in diabetic retinopathy

Diabetic retinopathy is one of the leading causes of vision loss and blindness in the world. The sequence of anatomical changes in the retina leading to blindness in diabetes is fairly well defined. There is general agreement that diabetic retinopathy can be classified into non-proliferative and proliferative stages [7]. Multiple progressive microvascular changes characterize these stages. The hallmark of the mild and moderate non-proliferative stage is leakage of the retinal vessels. The clinical findings are dot and blot hemorrhages, microaneurysms, venous dilatation, hard exudates and cotton-wool spots which are caused by microinfarction of the retina, and edema. The hallmark of the severe nonproliferative stage is ischemia of the retina. The clinical findings are four quadrants of microaneurysm and/or dot and blot hemorrhage, two quadrants of venous beading, and one quadrant of intraretinal microvascular abnormalities (IRMA). The hallmark of the proliferative stage is neovascularization. The clinical findings are retinal neovascularization, vitreous hemorrhage and retinal detachment.