This is a study of subjects with retinal vein occlusion (RVO) specifically looking at the difference in outcomes between patients with posterior vitreous detachment (PVD) and those without PVD. Posterior vitreous detachment is a condition where the gel-like substance that occupies the space between the retina and the lens of the eye liquefies and separates from the retina. 20 subjects from Barnes Retina Institute will be enrolled in this study. Based on a pre-treatment ultrasound (a test utilizing high-frequency sound waves to look at the inside of the eye), high resolution OCT (a noninvasive procedure called optical coherence tomography to check the thickness of your retina) and clinical exam, subjects will be assigned to one of 2 groups at baseline: Group 1 will be those with PVD and Group 2 will be those without PVD. Then subjects will receive monthly intravitreal (inside the eye) injections of Ranibizumab.