 The pathogenesis of macular edema in retinal vascular diseases is generally accepted to be increased levels of vascular endothelial growth factor VEGF due to ischemic or other stimuli. VEGF is known to be one of the most potent stimulators of vascular leakage in humans. Therefore, it seems sensible to study inhibition of VEGF to reduce vascular leakage, reduce macular edema, and improve vision in these retinal vascular disorders. 