Branch Retinal Vein Occlusion (BRVO)

Branch retinal vein occlusion (BRVO) refers to a blockage in any of the branches leading to the main vein of the eye. If the vein that is blocked is close to the center of the retina, i.e. the macula, then the resulting blood and fluid which may leak out of the damaged blood vessels may cause blurry and/or distorted vision. This is called macular edema and is the most frequent cause of loss of vision with a BRVO. Another possible cause of loss of vision is termed macular ischemia. This refers to a condition when the blood vessels that supply oxygen to the macula are so severely damaged that they can no longer function and close off, thereby depriving the macula of the oxygen and nutrients it requires. To help determine whether visual loss is a result of macular edema or macular ischemia, a fluorescein angiogrammay be performed. This is a test in which a dye is injected into a vein in the arm, and photographs are taken as the dye travels through the retinal blood vessels. If the damage to blood vessels is so severe as to cause widespread ischemia, then a third complication may occur termed neovascularization. This refers to the growth of new but fragile blood vessels which may bleed into the cavity of the eye (vitreous hemorrhage), or pull on the retina and cause a retinal detachment.