 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 various retinal vascular diseases including diabetic retinopathy and retinal vein occlusion. Silva et al revealed that retinal nonperfusion area was correlated highly with diabetic retinopathy severity in their recent paper. It should be clarified that retinal nonperfusion is not synonymous with retinal ischemia, which implies tissue hypoxia, but is a useful surrogate. 