Retinal vein occlusion (RVO) is one of the most common causes of sudden, painless, unilateral (affecting one eye) loss of vision. Although it can occur at almost any age, it typically affects people over the age of 60, and men slightly more often than women.
When one of the veins draining blood from the eye becomes blocked, blood and other fluids leak into the retina, causing bruising and swelling, starving retinal cells of oxygen and leading to sight loss.
Blockages in the veins draining blood from the eye are more common in people with high blood pressure, high cholesterol, glaucoma or diabetes, or smokers.
What causes retinal vein occlusion?
Most of the time the blockage happens in one of four “branch” veins that drain blood from the retina into the main central vein. This is referred to as a branch retinal vein occlusion (BRVO), and only part of the retina will be affected. Rarer central retinal vein occlusions (CRVO) are likely to cause more severe sight loss.
The key symptom is a sudden, painless loss of sight in one eye, which may become dimmer or more blurry over the course of several hours or days.
A small amount of bleeding and swelling may clear without treatment, so your doctor may decide not to treat you straight away.
If treatment is needed, a series of regular anti-VEGF injections may be given to slow the leakage from damaged blood vessels and preserve as much of your vision as possible. A steroid implant may also be injected into the eye, so it can release the drug gradually over four to six months.
For a few people with RVO, new blood vessels start to grow into the retina and iris (the coloured ring of muscle around the pupil). These can raise the pressure inside your eye or leak, which can both cause further sight loss, so it is important for you to be regularly monitored for these symptoms. New blood vessels may be treated with lasers to stop them spreading.
You should also be offered advice on reducing your risk of a future RVO and improving your general health by stopping smoking, losing weight or lowering your blood pressure.
Researchers are working to understand why some people are more likely to develop RVO, and why treatments work better for some people than others. New treatments, and combinations of existing treatments, are also being tested. It is possible that stem cell therapy will eventually allow areas of the retina, that have been damaged by RVO, to be replaced.