VEGFA and non-proliferative diabetic retinopathy: Experiments have revealed that intravitreal injection of VEGF can produce various symptoms of NPDR and PDR: nonperfused capillaries, vasodilatation, and tortuous arterioles characterized by endothelial hyperplasia and microaneurysms (61, 118, 119). The degree of damage to the external limiting membrane (ELM) is correlated positively with the level of serum VEGF, which suggests that the level of VEGF is related to the severity of DR and the degree of damage to the external limiting membrane. VEGF regulates DR-related inflammation in the early phase (118).