VEGFA and retinal ischemia: The retinal microvasculature is progressively damaged by the disease, resulting in various events such as retinal ischemia, upregulation of hypoxia inducible factor-1 (HIF-1), and vascular endothelial growth factor (VEGF) secretion, possibly progressing to PDR, which is diagnosed according to the presence of vascular lesions (e.g., preretinal or vitreous hemorrhages or neovascularization) (4).