This study will consist of 3 phases: a screening phase which will last up to two weeks, a confirmation phase which will last one day, and a randomization phase (the patient will be assigned by chance to a study group in this phase) which will last approximately 52 weeks.
Inclusion Criteria: * CRVO must have occurred within the past 6 months and be associated with macular edema determined by OCT. * Vision in the study eye corresponding to between approximately 20/50 to 20/400 and better than or equal to approximately 20/200 in the fellow eye. Exclusion Criteria: * Presence of signs of old branch retinal vein occlusion (BRVO) or CRVO in the study eye or any other retinal vascular disease including diabetic retinopathy. * Vitreous hemorrhage except breakthrough hemorrhage from intraretinal hemorrhage. * Prior pan retinal photocoagulation (PRP) or sector scatter photocoagulation.