AGTR1 and diabetic retinopathy: The role of angiotensin II in diabetic retinopathy has been studied clinically in the Diabetic Retinopathy Candesartan Trials (DIRECTs) [31, 32], in which the effect of an AT1R blocker on the incidence and progression of diabetic retinopathy was evaluated using the Early Treatment Diabetic Retinopathy Study (ETDRS) scale.