Definition and Classification of Retinal Vein Occlusion

Abstract

Retinal vein occlusion is second most common retinal vascular disease after diabetic retinopathy. A main cause of the retinal vein occlusion is arterial disease when arterial stiffness affects neighboring vein. There are three main types of retinal vein occlusion: central retinal vein occlusion, hemicentral retinal vein occlusion and branch retinal vein occlusion. Central retinal vein occlusion and hemicentral retinal vein occlusion can be further divided into non-ischemic and ischemic types. Branch retinal vein occlusion can be further divided into major branch retinal vein occlusion and macular branch retinal vein occlusion based on the location of the occlusion. Retinal vein occlusion is a major cause of vision loss. Of the two main types of retinal vein occlusion, branch retinal vein occlusion, is 4- to 6-times more prevalent than central retinal vein occlusion. A common risk factor for retinal vein occlusion is advancing age, and additional risk factors include systemic conditions such as hypertension, arteriosclerosis, diabetes mellitus, hyperlipidemia, vascular cerebral stroke, blood hyperviscosity and thrombophilia. Ophthalmic risk factors for retinal vein occlusion are ocular hypertension and glaucoma, higher ocular perfusion pressure and changes in the retinal arteries.