Safety and Effectiveness of Bevacizumab Intravitreal Injections in the Treatment of Macular Edema Secondary to Retinal Vein Occlusion

Inclusion Criteria: * Patient male or female 18 years old or more * Foveal macular edema secondary to Retinal Vein Occlusion confirmed by Fluorescein angiography and Optical Coherence Tomography, with a subcentral field thickness of at least 250 microns * Patients with best corrected visual acuity loss within the last 6 months of evolution, caused by the macular edema as stated by investigator´s judgement. * Best corrected visual acuity tested by ETDRS within 20/40 and 20/400 in the study eye. * Signed Informed consent. * Signed Data Protection Consent. * Negative pregnancy test before entering the study for childbearing potential women, who must commit to use a medically accepted contraceptive method for the whole study. * Macular Subcentral field assessed by Ocular coherence tomography of at least 250 microns thick. * No presence of eye opacities that may prevent fundus exploration. No condition that may prevent correct eye dilation. * No known allergy to fluorescein. * Only an eye per patient will be included in the study,even if both eyes have the pathology. Exclusion Criteria: * Macular edema secondary to any other condition such as: diabetes retinopathy, hypertension, Juxtafoveal telangiectasia, ... * Any previous treatment for macular edema such as photocoagulation, vitrectomy, triamcinolone, radial optic neurotomy, ... in the study eye. * Any ocular illness thay may be associated to increased/high levels of VEGF (Age related macular degeneration, Diabetes retinopathy, Uveitis, ...) * Systemical illnesses thay may be associated to increased/high levels of VEGF (e.g. tumours). * Medical history of brain vascular episodes (stroke), ictus, angor pectoris or myocardial infarct within 3 months before study inclusion. * Pregnancy or nursing. * Hypersensibility known or suspected to Bevacizumab, his excipients or any related molecule. * Uncontrolled hypertension refractary to medical treatment. * Participation in any other trial or study within the last 3 months (minerals and vitamins excluded) or treatment with anti-VEGF in the non-study eye within the previous 3 months. * Tractional maculopathy and/or epiretinal membrane assessed by Ocular Coherence Tomography. * Media opacities that don´t allow correct eye exploration and fundus examination/photographs. * Cataract surgery / Yag capsulotomy within the previous 6 months. * Filtration surgery. * Previous medical history of ocular illnesses as: viral infections, inflammatory pathology, serous central choroidopathy, retinal detachment or any other illness that may have an influence in visual acuity. * Presence of foveal atrophy, severe pigmentary changes, dense subfoveal haemorrhages, confluent subfoveal hard exudates or any other condition that may influence functional recovery of the macular edema. * Cataract that may be responsible for additional visual acuity loss of more than 2/10. * Medically uncontrolled intraocular pressure higher than 25 mm Hg. * External ocular illnesses active at inclusion as: conjunctivitis, blepharitis, eye sore, ...