VEGFA and diabetic macular edema: Pathological retinal angiogenesis plays a crucial role in etiopathogenesis of various VEGF-dependent retinal diseases, such as age-related macular degeneration (AMD), proliferative diabetic retinopathy (PDR), diabetic macular edema (DMO), central retinal vein occlusion (CRVO) or retinopathy of prematurity (ROP), which are the main causes of serious vision impartment or blindness in human.