Retinal Vein Occlusions

What is a retinal vein occlusion?
A retinal vein occlusion means that a vein in the retina of the eye has become blocked. The retina is the light sensing tissue at the back of the eye. The veins drain blood out of the retina and return it to the heart. Blockage or occlusion in the vein prevents adequate blood flow in the affected area. The walls of the blocked vein tend to leak blood and excess fluid into the retina. The retina in the area that is drained by that particular occluded vein then becomes swollen and functions poorly.

What are the types of retinal vein occlusion?
There are two types of retinal vein occlusion. In central retinal vein occlusion (CRVO), the main retinal vein is blocked. Blood flow is poor throughout the entire retina. The amount of visual loss varies, but may be severe. In branch retinal vein occlusion (BRVO), a smaller branch of the main retinal vein is blocked. Only the part of the retina drained by this branch vein is damaged. Vision loss varies but is not as severe as in CRVO. Retinal vein occlusions are more common in people who have high eye pressure, diabetes, age-related vascular (blood vessel) disease, or high blood pressure.

What are the symptoms of retinal vein occlusion?
Blurred vision is the main symptom of retinal vein occlusion. It occurs when the excess fluid leaking from the vein collects in the macula. The macula is the central area of the retina which is responsible for our central, detailed vision. If the macula swells with excess fluid (macular edema), vision becomes blurred.
Floaters can appear as spots which interfere with vision. When retinal blood vessels are not working properly, the retina may grow abnormal blood vessels (neovascularization) which are fragile. They can bleed or leak fluid into the vitreous, the gel-like fluid that fills the center of the eye, causing the floaters.

Pain in the eye sometimes occurs as a complication of severe CRVO. It is caused by excessive eye pressure called neovascular glaucoma.

Laser surgery is very effective in preventing vitreous hemorrhage and neovascular glaucoma. However, it does not remove a hemorrhage or cure neovascular glaucoma once they are already present. It is best to treat people at risk for these complications before they occur. Your ophthalmologist will decide whether laser surgery is appropriate for you. You should make sure that any associated medical condition is treated by your regular physician.

What tests might the doctor order?
After a complete eye examination, your ophthalmologist may order blood tests and/or a test of the retinal circulation called fluorescein angiography. A dye (fluorescein) is injected into your arm and special photos are taken of the inside of your eye as the dye passes through the blood vessels. Your ophthalmologist may also suggest a visit to your family physician to discover and manage any associated medical problems.

What treatment is available?
There is no cure for retinal vein occlusion. Your ophthalmologist may recommend a period of observation, since hemorrhages and excess fluid may subside on their own. Laser surgery improves sight in some patients with macular edema, but vision does not usually return to normal.