The retinal vein occlusion (RVO) is the second most common retinal disease after diabetic retinopathy, and is a common cause of unilateral visual loss. The risk factors that predispose to RVO are many and are generally the same as those found in vascular alterations involving other parts of the body, as in the case of stroke or coronary heart disease. Several authors have attempted to determine whether the pathogenesis of RVO can be of arterial type, considering the disease as consequent to atherosclerosis, rather than resulting from venous disease. Although less frequent than the other diseases RVO affects considerably on health care costs. Direct medical costs showed that in one year a patient with this disease has a higher than average cost for a patient with hypertension or glaucoma. Knowing the prevalence of the disease in Italy and identify modifiable risk factors, recognizing additional risk factors related to gender, genetic predisposition and especially the social-economic and cultural background in the pathogenesis of RVO, are the objectives that led to the planning of this study. In order to assess the prevalence of the disease and the current "clinical practice" we aim to create an online register between Italian specialist centers (ophthalmic emergency care and thrombosis centers) with immediate portability and usability of the data.