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Central Retinal Vein Occlusion (CRVO) occurs when the main retinal vein is blocked. Because the blood can no longer travel out of the retina smoothly, the retina becomes filled with blood and swollen. If the blockage is partial, the retina may continue to function adequately. If the blockage is more severe, permanent retinal damage may occur with loss of vision. Central retinal vein occlusions occur most commonly in people who have high blood pressure, diabetes or glaucoma. Occasionally, the damage to the retina will result in abnormal new vessel growth. Further visual loss can occur if these abnormal vessels break and bleed into the vitreous cavity, causing a vitreous hemorrhage. When the abnormal vessels grow in the front of the eye they often cause severe and painful glaucoma. Glaucoma (elevated intraocular pressure) caused by vessels growing in the front of the eye is called rubeotic glaucoma. Rubeosis Rubeosis is a condition in which abnormal blood vessels grown on the iris or colored part of the eye between the cornea and the lens. These abnormal blood vessels can block the flow of fluid from the eye and result in severe glaucoma. This is called Neovascular Glaucoma and can cause pain or rapid loss of vision. Prompt laser treatments and sometimes surgery is required to control neovascular glaucoma. Symptoms of CRVO Patients with central retinal vein occlusion usually have blurred vision from retinal hemorrhage and swelling. Spots, strands or curtains in the vision may occur due to vitreous hemorrhage. Eye pain may be caused by neovascular glaucoma. Evaluation of CRVO In addition to a dilated eye exam, a test called Fluorescein Angiography may be required. During this test a dye is injected into a vein in the arm. Special photographs are taken of the retina as the dye passes though the eye. The abnormal blood vessels leak the injected dye and become detectable to the physician. This test aids the diagnosis and may help determine the need for laser treatment. Treatment for CRVO Presently there is no proven treatment for CRVO itself. When CRVO cause complications such as abnormal new blood vessel growth, treatment is often required. If untreated, these abnormal blood vessels can cause vitreous hemorrhage and glaucoma. Laser treatment is used to reverse the growth of abnormal new blood vessels. There are new therapies for treating CRVO which may hold promise to the future. |
 Central Retinal Vein Occlusion |
 Rubeosis |
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 Fluorescein Angiography of CRVO with Delayed Filling of Veins |
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Branch Retinal Vein Occlusion (BRVO) is similar to a central retinal vein occlusion, but only affects a segment of the retina. A BRVO occurs when a branch of the retinal vein becomes blocked. The blockage usually occurs where a retinal artery crosses over and compresses a retinal vein. The segment of the retinal drained by the blocked vein becomes swollen with blood. Where the vessel is blocked it often leaks, causing retinal swelling. When swelling occurs in the central retina it is called macular edema, and may result in loss of vision. As in CRVO, vision loss can also occur if abnormal blood vessels grow in the front or back of the eye. Symptoms of BRVO Patients with a BRVO often have blurred vision from retinal hemorrhage or macular edema. Occasionally spots, strands or a curtain may occur due to vitreous hemorrhage. Eye pain may be caused by glaucoma. Evaluation of BRVO In addition to a dilated eye exam, a test called Fluorescein Angiography may be required. During this test a dye is injected into a vein in the arm. Special photographs are taken of the retina as the dye passes through the eye. Blocked or abnormal blood vessels will become detectable to the physician. This test aids the diagnosis and may help determine the need for laser treatment. Treatment of BRVO If vision loss is due to macular edema, laser treatment may be recommended. Laser treatment will decrease the leakage which is causing macular edema. Studies have shown that patients who receive laser for macular edema are twice as likely to regain good vision. If abnormal blood vessels are growing in the eye, more extensive laser treatment may be necessary. There are new therapies for BRVO which may hold promise for the future. |
Branch Retinal Vein Occlusion |
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 Fluorescein Angiography of BRVO |
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 Laser Treatment of BRVO |
