The objectives of this study were to characterize the differential potency of two major VEGF isoforms, VEGF(120) and VEGF(164), for inducing leukocyte stasis (leukostasis) within the retinal vasculature and blood-retinal barrier (BRB) breakdown and to determine whether endogenous VEGF(164) mediates retinal leukostasis and BRB breakdown in early and established diabetes.