Most people know that high blood pressure and other vascular (blood vessel) diseases pose risks to overall health, but many may not know that high blood pressure can affect vision by damaging the veins in the eye. High blood pressure is the most common condition associated with branch retinal vein occlusion (BRVO). About 10% to 12% of the people who have BRVO also have glaucoma (a disease of the nerve between the eye and the brain).
BRVO is a disease of the retina. The retina is a layer of light-sensing cells lining the back of your eye. This condition often damages a portion of the retina called the macula, which is located in the center of the retina and enables you to see fine details clearly. You rely on your macula whenever you read, drive, or do other activities that require you to focus on fine details.
BRVO blocks the veins in the retina, and is often referred to as a blood clot in the retina. If the blocked retinal veins are ones that nourish the macula, central vision may be lost completely or in part. In addition to the blockage of retinal veins, more than one-half of people with BRVO will develop swelling of the macula (see section on macular edema). In about one-third of people, this macular edema will be difficult to treat and will last for more than one year.
BRVO causes a painless decrease in vision, resulting in misty or distorted vision. If the blockage of the veins is severe and prevents blood flow to a large area, then new abnormal vessels may grow on the retinal surface (called neovascularization), which can bleed into the eye and also cause decrease in vision.
The first step in treatment is finding out what caused the blockage is the first place. Your eye doctor may send you to your family doctor or internist to assist in looking for a medical condition that may have caused the vein occlusion. Your eye doctor also may recommend a period of observation, since hemorrhages and excess fluid may subside on their own. Depending on the condition in the retina, laser surgery or an injection of medication may help reduce the swelling and may improve vision. Laser surgery or an injection of medication may also help protect against new abnormal vessels may grow on the retinal surface (called neovascularization), which can bleed into the eye and also cause decrease in vision.
If you have had a BRVO, regular visits to your eye doctor are essential to protect vision. Be sure to discuss your options with your eye doctor.