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Natural evolution of severe central retinal vein occlusion with low visual acuity is very poor. A randomized clinical trial will compare troxerutin and platelet anti-aggregating agents (drug treatment) versus surgery and drug treatment. Surgery will include vitrectomy and radial optic neurotomy. The primary outcome will be vision measured 6 months after surgery.

Central Retinal Vein Occlusion (CRVO) is the second most frequently retinal vascular disease causing loss of vision, after diabetic retinopathy. No treatment of CRVO has clearly demonstrated beneficial and long lasting visual results. Commonly used treatment options are platelet anti-aggregating agents, correcting rheologic factors with troxerutin and isovolumic hemodilution. Surgical treatment of CRVO has recently been proposed (2001) and has been studied in numerous non comparative pilot studies. Limited but encouraging results motivate our randomised controlled trial. We will evaluate at 6 months visual acuity after surgery associating pars plana vitrectomy and radial optic neurotomy, in patients with central vein occlusion and bad vision, associated with the correction of rheologic factors.

Inclusion Criteria:

• Central Retinal Vein Occlusion oedematous or hemorrhagic (at fundus exam and at fluorescein angiography)
• Visual Acuity (VA) ≤ 20/200 with ETDRS charts
• Decreased VA since more than 1 month, less than 3 months
• Common care recommendations for CRVO during the period before recruitment (Control ocular pressure if associated hypertension or glaucoma ; Hemodilution if hematocrit ≥ 38% ,if no cardio-vascular contra-indication, to maintain hematocrit under 38% during 6 weeks ; Troxerutin (3 /d) and aspirin (100 - 160 mg/d) ; Clinical and angiographic controls to look for retinal ischemia indicating laser PRP to prevent neovascular glaucoma.
• Signed informed consent.

Exclusion Criteria:

• Ischemic CRVO : 1- More than 30 disc diameters of ischemia at fluorescein angiography and/or •2- If Angiogram is uninterpretable because of hemorrhages, deficit of afferent pupillary reflex 0.9 with photographic filters (proposed by Hayreh) with indication to do laser PRP or laser PRP already done,
• Rubeosis or neovascular glaucoma,
• Bilateral diabetic retinopathy preproliferative or proliferative,
• Uncharacterized coagulation disease, or anticoagulant treatment,
• Untreated systemic disease (diabetes, severe high blood pressure, Cardiac failure) ou eye disease (glaucoma),
• Contra-indication or documented allergy to troxerutin or platelet anti-aggregating agents,
• Contra-indication to surgical procedure
• incapacity to received an informed consent, incapacity to follow all the study schedule