VEGFA and retinal vein occlusion: The pathogenesis of ME in retinal vein occlusion is not completely understood but may result from a variety of factors, including hydrostatic effects from increased venous pressure, the presence of inflammatory cytokines, the dysregulation of endothelial tight junction proteins [2], or increased amounts of vascular permeability factors, such as vascular endothelial growth factor (VEGF) [3].