Central Retinal Vein Occlusion
Branch retinal vein occlusion occurs when part of the venous drainage system of the retina is blocked. The branch retinal veins drain the blood into the central retinal vein after it passes through the retinal arterioles and capillaries. These occlusions are the most common cause of retinal vascular occlusive disease. A blockage in one of these branch retinal veins causes back-pressure and leads to hemorrhage, exudation, and or decreased blood flow in the area of the retina drained by that particular retinal vein. Males and females are affected equally. Like the central retinal vein occlusion, most occur after age 50.
Both occlusions are similar to those for vascular occlusive disease (elsewhere in the body), such as stroke and coronary artery disease. Aging, high blood pressure, diabetes, and smoking are risk factors for central and branch retinal vein occlusion.