Retinal Vein Occlusions
A retinal vein occlusion occurs when one of the veins in the retina is blocked (occluded) and cannot drain blood from the retina. This blockage causes damage to the vein and leads to a backup of blood. The damaged vein often leaks blood and fluid which can be seen as hemorrhages and edema (swelling) of the retina, respectively. Hemorrhages and swelling varies and depends on the severity of the blockage. Clinical research studies have suggested several risk factors associated with retinal vein occlusions. These include hypertension, glaucoma, blood clotting disorders, and age. All patients with retinal vein occlusions should be evaluated by their family physician to ensure blood pressure is adequately controlled.
Types of retinal vein occlusions
When the major vein that drains the blood from the retina is blocked, this is called a central retinal vein occlusion (CRVO). In this case, retinal hemorrhages are scattered throughout the retina and macular edema can develop (swelling in the center part of the retina). When the blockage involves a smaller vein, this is called a branch retinal vein occlusion (BRVO). Retinal hemorrhages are found in the area of the retina that is drained by the affected vein. Macular edema can also develop with a BRVO.
Branch Retinal Vein Occlusion (BRVO)
Central Retinal Vein Occlusion (CRVO)
The symptoms of retinal vein occlusions can vary but include: blurry vision, distortion, new floaters, and rarely pain for elevated eye pressure. Some patients do not have any symptoms.
Your doctor can diagnose a retinal vein occlusion by looking at your retina during a dilated eye exam. Sometimes your doctor may recommend other diagnostic tests, including fluorescein angiogram and optical coherence tomography (OCT). These special tests can help to evaluate the amount of swelling in the retina and extent of the blockage. These tests are often repeated at a later time for comparison.
Unfortunately, there is no cure for retinal vein occlusions. The main cause of vision loss in patients with retinal vein occlusions is due to macular edema, or swelling in the center part of the retina. Therefore, most of our treatments are directed towards reducing this swelling. Treatment options include injections of steroids or other medications (Avastin and Lucentis), laser treatment, or participation in a clinical research trial. Some patients do not have macular edema and can be observed without treatment. In severe cases, abnormal blood vessels grow which can cause painful glaucoma. In these cases, laser treatment and/or injections of medicine (Avastin or Lucentis) are necessary. Some patients require surgery to control eye pressure despite using laser and injections.