Studies demonstrate that tight junctions in the vessel walls were shown to be regulated by VEGF and VEGF increases vascular permeability (Anticliff et al. 1999). The healthy human retina contains little or no VEGF. Hypoxia, a component of diabetic retinopathy, causes upregulation of VEGF in the retina (Vinores et al. 1997). Binding VEGF with an antibody specific for VEGF may inhibit resultant edema thus preventing and possibly reversing loss of vision.