VEGFA and ischemia: Retinal vein occlusion is a precipitating event that leads to baseline ischemia and release of the vascular endothelial growth factor (VEGF), which then contributes to progression of NPA and thus worsening of ischemia [17].Nonperfused areas (NPAs) form in relation with retinal artery or vein occlusion, which is a significant sign for ischemia.