Diabetic retinopathy is one of the leading causes of blindness in the world. Signs of retinopathy are detected in almost 100% of type 1 diabetic patients who have had their disease for at least 20 years and almost 100% of type 2 diabetic patients with the similar duration of disease (1). Histopathologic findings range from microaneurysms and cotton wool spots to more ominous neovascularization. The latter process, known as proliferative diabetic retinopathy, can progress to total blindness if untreated. The biochemical mechanisms responsible for PDR have been extensively studied, and appear to be multifactorial. Associated findings include abnormalities of vasoactive peptides such as vascular endothelial growth factor (VEGF), pigment epithelium derived factor (PEDF), and insulin-like growth factor (ILF-1), lipids, oxidative pathways, enzymatic pathways, such as protein kinase, and carbohydrate metabolism (1-4). Whether these (and other) factors are interrelated or have a common underlying defect is unknown. The common endpoint, however, is vascular leakage with neovascularization. Current therapeutic regimens based on these biochemical abnormalities have to date been unsuccessful in stemming the progression of proliferative diabetic retinopathy. Current treatment strategies emphasize glycemic and blood pressure control, with laser photocoagulation and vitrectomy for advanced cases (5).