Fig. 4

Capillary obstruction due to leukostasis and capillary dropout due to death of vascular pericytes and endothelial cells lead to tissue ischemia. Resulting hypoxia may drive expression of vascular endothelial growth factor-A (VEGF-A). VEGF-A promotes vascular permeability resulting in leakage of plasma through the blood–retinal barrier (BRB) and tissue edema through its interactions with VEGF receptor 2 (VEGFR-2) on vascular endothelial cells. RBC red blood cell