Branch Retinal Vein Occlusion
Branch retinal vein occlusion (BRVO) is a cause of painless vision loss in the upper, lower, or central field of vision. It may also occur with no symptoms. Occlusion occurs when blood flow in a vein is reduced or blocked.
When BRVO occurs, we look for associated conditions. If vision is affected, treatment with a laser may improve vision or reduce the risk of further vision loss. In most cases, we wait for spontaneous improvement. If vision is blurred, treatment is guided by techniques that have been tested in national controlled clinical trials. In BRVO, an artery crossing over the retinal vein at the point of obstruction is usually present. This can pinch the vein, like stepping on a garden hose, thereby cutting off blood flow. The area of the retina that drained through this vein may become congested or swollen. Areas of the retina may bleed or die. Sometimes the obstruction is reversible, and sometimes it is irreversible. The leading cause of blurred vision in BRVO is macular edema, in which swelling of the central retina is caused when blood cannot flow through the blocked vein, allowing water to leak into the retina.