Comparing ranibizumab and aflibercept in a treat and extend algorithm evaluating the number of needed injections over a 18 month period in patients with newly diagnosed CRVO.

Forty patients diagnosed with a new central retinal vein occlusion (CRVO) of a maximum duration of 6 months will be recruited to the study. Patients will be randomized 1:1 to treatment with aflibercept ot ranibizumab.

all patients will receive 3 initial monthly injections. There after injections will be given att every visit according to a treat and extend schedule. If no macular edema is seen on the Ocular coherent tomography (OCT) examination the next treatment will be after 6 weeks. If the macula is dry after 6 weeks a new injection is given and the next visit is scheduled for another 8 weeks. If edema is seen on the OCT after 8 weeks the time to next injection is reduced to 6 weeks. Patients cannot receive an injection more often than every 4 weeks. All patients will receive an injection at least every 12 weeks.

Primary outcome: the number of needed injections over a 18 month period comparing ranibizumab and aflibercept.

Secondary outcome: Change in visual acuity, change in macular thickness. A subgroup of patients will also be evaluated with OCT angiography. A possible relationship between the Visual acuity and the foveal avascular zone will be evaluated.

Inclusion Criteria:

• CRVO - naive patients, disease duration maximum 12 months, Best corrected visual acuity : 23-73 letters (20/40 - 20/320), Macular edema > 300 μm (Cirrus)

Exclusion Criteria:

• Neovascular Glaucoma Any previous treatment for CRVO. Intraocular surgery during the previous 3 months. Vascular retinopathy of other causes. Glaucoma with uncontrolled IOP (intra ocular pressure) Myocardial infarction or stroke during the last 3 months.