- The study eye shows evidence of definite retinal thickening due to a BRVO based on clinical examination involving the center of the macula that is not refractory to further therapy as based on the investigator s clinical judgment. BRVO is defined as an eye that had retinal hemorrhage or other biomicroscopic evidence of RVO (e.g., telangiectatic capillary bed) and a dilated (or previously dilated) venous system in one or two quadrants or less of the retina drained by the affected vein. Hemiretinal vein occlusion (HRVO) is an RVO that involves two altitudinal quadrants. In this study, eyes with a HRVO will be considered a BRVO and are given the same treatment as BRVO eyes.