A branch retinal vein occlusion is an obstructed or blocked vein in the retina at the back of the eye. You may recall that arteries bring fresh nutrients and oxygen-rich blood to the tissues, and that veins drain away that oxygen- and nutrient-depleted blood. While blood flow into the eye is important, blood flow out is equally important to maintain circulation. When outflow is blocked, as in a retinal vein occlusion, the blood has no place to go, and “backs up”, rupturing the blood vessel walls. Without a way for the blood to flow out of the eye, blood overflows on and into the retina. Similar to the swelling that occurs when a tourniquet is kept in place on an arm too long, swelling (edema) occurs in the retina.
The degree of visual loss will depend on how close the blood vessel blockage is to the center of vision (the macula) and whether the blockage is partial or complete. Branch retinal occlusions may cause significant damage to vision. Depending on the duration and extent of the blockage, your vision may improve, worsen, or remain the same.
Vein occlusions can occasionally be complicated by abnormal blood vessel growth, which can later result in bleeding into the vitreous jelly of the eye or severe glaucoma. Careful follow-up examinations will monitor and allow early detection of these uncommon complications.
A special in-office test called a fluorescein angiogram or an OCT (optical coherence tomography) may be used to help confirm the diagnosis or guide treatment. The test is valuable because it will demonstrate the degree of diseased retina, and even reveal hidden damage, providing critical information for both treatment and predicting visual recovery.
Fortunately, there are treatments for branch retinal vein occlusions. If your vision does not improve significantly, or if your vision remains poor, laser eye surgery may be recommended. Laser treatments almost double the chance for visual improvement in cases where there is macular edema.
Another treatment for macular edema is the injection of medications into the eye such as steroids or vascular endothelial growth factor inhibitors. For those more serious cases where abnormal vessel growth occurs, a more extensive laser treatment may be utilized. In those rare eyes with bleeding into the vitreous (jelly inside the eye) that fail to respond to conventional treatment, then vitreous surgery to remove the blood in the jelly of the eye becomes an option. This is inpatient surgery that may require a hospital stay. It is often combined with laser treatment.
Certain medical conditions increase the risk of developing these blood vessel blockages. The most common include hypertension (high blood pressure), diabetes, or atherosclerosis (hardening of the arteries, and especially carotid artery narrowing). Therefore, referral to your general medical doctor for reevaluation of these conditions may be valuable. Recognition and control of these medical conditions may prevent these blood vessel blockages from recurring in this eye, occurring in the other eye, or elsewhere in the body.