Branch Retinal Vein Occlusion
The retina is fed by a system of blood vessels (arteries and veins) like a tree, with the trunk in the optic nerve and branches extending to the farthest edges of the retina. A branch retinal vein occlusion (BRVO) is vein blockage along a branch of the tree, usually at a point where an artery crosses over a vein and compresses it. This results in poor blood flow to a section of the retina. Since the retina is like film in a camera, a patient experiences branch retinal vein occlusion as painless vision loss. If the vein occlusion is away from the center or the retina, central vision may be unaffected. If the vein occlusion affects the central retina, vision may be severely limited.
Branch retinal vein occlusion occurs most often in patients with high blood pressure, diabetes, high cholesterol , atherosclerosis, or high intraocular pressure (glaucoma). Smoking is also a major risk factor for BRVO. In some cases, no clear cause is found for BRVO, and in some cases BRVO is caused by rare conditions such as blood disorders that cause spontaneous clotting. Your doctor will determine the appropriate workup for underlying causes of BRVO depending on your age and medical history.
Your retinal surgeon may order diagnostic tests in the office to determine the degree of damage caused by the vein occlusion. Blood flow in the affected area may be permanently reduced. Swelling may occur in the central part of the retina (the macula) resulting in decreased vision. In some cases, the eye may grow abnormal blood vessels. These complications of BRVO can be detected by a combination of clinical examination and imaging tests. Optical coherence tomography (OCT) is a fast, non-invasive scan of the retina which measures and locates swelling in the retina. Fluorescein angiography (FA) evaluates blood flow in the retina with a series of photographs taken after intravenous injection of a dye (fluorescein).
If swelling (macular edema) is present, your retinal surgeon may recommend one or more treatments including laser or injection of medicine into the eye. If the eye is growing abnormal blood vessels (neovascularization), your surgeon may recommend laser treatment. In some cases, micro-incisional sutureless vitrectomy surgery is recommended. In all cases, treatment of underlying medical conditions such as high blood pressure is critical to preventing another retinal vein occlusion in the future.
Treatments for macular edema associated with branch retinal vein occlusion include laser, intravitreal injection (injection of medicine into the eye), or surgery. Medications which can be injected into the eye in these cases include bevacizumab (Avastin, which is used off-label for this condition), ranibizumab (Lucentis, which is FDA approved for this condition), aflibercept (Eylea, which is FDA approved for this condition), and dexamethasone (Ozurdex steroid implant, which is FDA approved for this condition).