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 our 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 vein leak blood and excess fluid into the retina.
There are two types of retinal vein occlusion. Central retinal vein occlusion (CRVO) describes a situation where the main retinal vein is blocked and blood flow is poor throughout the entire retina. The amount of visual loss varies in younger people but is often severe in older people. Branch retinal vein occlusion (BRVO) occurs when a smaller branch of the main retinal vein is blocked. With BRVO, 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 glaucoma, diabetes, age-related vascular (blood vessel) disease, high blood pressure and blood disorders.
The main symptom of a retinal vein occlusion is blurred vision. The blurring occurs when the excess fluid leaking from the vein collects in the macula. The macula is the central area of the retina that is responsible for our central, detailed vision. If the macula swells with excess fluid (macular edema), vision blurs.
Other less common symptoms include floaters and eye pain. When retinal blood vessels are not working properly, the retina may grow abnormal blood vessels (neovascularization) that are fragile. They can bleed or leak fluid into the vitreous, the gel-like fluid that fills the center of the eye may cause floaters. Finally, pain in the eye sometimes occurs as a complication of severe CRVO. It is caused by excessive eye pressure called neovascular glaucoma.
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.
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.
Laser surgery is very effective in preventing vitreous hemorrhages 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.