Numerous studies on RAS components in the retina have shown increased levels of prorenin, renin, and angiotensin II in the vitreous of the patients with proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME), suggesting the essential role of RAS in the pathogenesis of diabetic retinopathy [7, 8]. This evidence concerns the gene REN and diabetic retinopathy.