The purpose of this study is to compare ranibizumab injection to hemodilution at the early phase of Central Retinal Vein Occlusion (CRVO) and to determine if the combination of both treatments may have a synergic effect.

Patients with recent-onset CRVO (lasting for less than 1 month)are randomly assigned to one of 3 groups: hemodilution using erythrocytapheresis alone, 3 monthly injection of ranibizumab alone, or both.

Patients are followed monthly during the 6-month study.

Inclusion Criteria:

• CRVO confirmed by fluorescein angiography
• duration from onset of 1 month or less
• visual acuity of 20/32 or less

Exclusion Criteria:

• neovascular complication
• extensive retinal ischemia requiring prompt panretinal photocoagulation
• hematocrit level lower than 38%
• previous laser or surgery in the study eye, etc