What is Retinal Vein Occlusion?
Retinal vein occlusion (RVO) results from the blockage of a branch of retinal veins or the central retinal vein by a blood clot. The occlusion of the retinal veins leads to backup of the blood into the retina. The blood that has backed up becomes stagnant and leads to lack of oxygen getting to the retina.
RVO can cause sudden or gradual (days to weeks) painless vision loss, sensitivity to light, or it can be present without any symptoms at all.
RVO does not have a racial predilection. It is slightly more common in males than females. A majority of cases of RVO occur in people over the age of 50, but it can occur in all age groups.
The common signs of RVO include: bleeding throughout the retina, engorged blood vessels, retinal swelling, and growth of new blood vessels in the retina or iris. In branch retinal vein occlusions, the signs only affect one quadrant of the retina, whereas in central retinal vein occlusions, the signs affect the entire retina.
How RVO develop is not exactly known, but various risk factors contribute to the occlusion of the retinal veins.
Risk factors include:
- High blood pressure
- Increased blood viscosity
- Use of oral contraceptives
- Cardiovascular disorders
- Bleeding disorders
- Clotting disorders
- Autoimmune disorders
- Inflammation of blood vessels
- Closed head trauma
The fellow eye may develop RVO in about 7 percent of cases within two years. There is a 2.5 percent risk of developing another RVO in the same eye and about 12 percent risk in the fellow eye within four years.
Proper evaluation and management by an eye doctor is essential to correctly diagnose retinal vein occlusions. The diagnosis of RVO is made by a dilated eye exam.
Although there are no known effective treatments for RVO itself, there are treatments available to manage the complications associated with RVO, such as laser surgery to stop new blood vessel growth or injections to resolve swelling in the macula. It is also important to see a primary medical doctor to treat the underlying systemic medical conditions to reduce further complications.
Currently in clinical trials, the National Eye Institute is funding research throughout the country to evaluate the effects of an injection steroid treatment versus traditional treatment for treating macular swelling (observation for CRVO; laser surgery for BRVO). The patients will be followed for three years to determine the long-term safety and efficacy of the treatment.