 Retinal nonperfusion drives vision-threatening complications such as pathological neovascularization, which can lead to neovascular glaucoma, vitreous hemorrhage, or tractional retinal detachments and macular edema in diabetic retinopathy. Thus, decreasing nonperfusion area with aid of anti-VEGF agents might be a useful way to prevent deteriorating course of diabetic retinopathy. The main purpose of this study is to determine the efficacy of intravitreal aflibercept injection in improvement of retinal nonperfusion and identify associated factors in patients with nonproliferative diabetic retinopathy with moderate retinal nonperfusion. 