Retinal vein occlusion is a blockage of the veins that carry blood away from the retina. The retina is the layer of tissue at the back of the inner eye that converts light images to nerve signals and sends them to the brain. Disruption of the blood vessels in the retina often results in blurred vision.
Causes, Incidence, and Risk Factors
Retinal vein occlusion is most often caused by hardening of the arteries (atherosclerosis) and the formation of a blood clot. Blockage of smaller veins (branch retinal vein occlusion or BRVO) in the retina often occurs when retinal arteries that have been thickened or hardened by atherosclerosis cross over and place pressure on a retinal vein. In central retinal vein occlusion (CRVO), it is presumed that a clot forms in the major vessel draining blood from the entire retina.
Risk factors for retinal vein occlusion include:
- High blood pressure (hypertension)
- Other Eye Conditions, such as glaucoma, macular edema, or vitreous hemorrhage.
Because the risk of these disorders increases with age, retinal vein occlusion most often affects older people.
Blockage of retinal veins may cause other eye problems, including:
- Glaucoma (high pressure in the arteries), caused by new, abnormal blood vessels growing in the front part of the eye
- Macular edema, caused by the leakage of fluid in the retina
- Sudden blurring or vision loss in all or part of one eye
Signs and Tests
To evaluate a retinal vein occlusion, the eye care doctor will need to dilate the pupils to examine the retina. Other tests that may also be done include retinal photography, fluorescein angiography and ocular coherence tomography.
Besides special eye examinations, other tests may include:
- Blood tests for diabetes, high cholesterol, and triglyceride levels
- Blood tests to look for a clotting or blood thickening (hyperviscosity) problem (particularly in younger patients)
The eye care doctor will closely monitor any blockage for several months. Many harmful effects, such as glaucoma, may take 3 or more months to develop after the occlusion.
Many people will regain vision, even without treatment. However, vision rarely returns to normal. You may need treatment to prevent another blockage from forming in the same or the other eye. It’s important to manage diabetes, high blood pressure, and high cholesterol levels. Certain patients may be prescribed aspirin or other blood thinners.
Treatment for the complications of retinal vein occlusion may include:
- Focal laser treatment, if macular edema is present.
- Injections of anti-vascular endothelial growth factor (anti-VEGF) drugs into the eye. These drugs, including Lucentis®, may block the growth of new blood vessels that can cause glaucoma as well as reduce macular edema.
- Injection of corticosteroids or steroid-containing biological formulations into the eye.
- Laser treatment to prevent the growth of new, abnormal blood vessels that leads to glaucoma.
The outcome varies. Some patients with retinal vein occlusion regain useful vision while others may not despite treatment. It is important to properly manage complications, such as macular edema and glaucoma. However, having either of these complications is more likely to lead to a poor outcome.
- Partial or complete vision loss in the affected eye Prevention
Retinal vein occlusion is a sign of a general blood vessel (vascular) disease. The same measures used to prevent other blood vessel diseases, such as coronary artery disease, may decrease the risk of retinal vein occlusion.
These measures include:
- Eating a low-fat diet
- Getting regular exercise
- Maintaining an ideal weight
- Not smoking
Aspirin or other blood thinners may help prevent blockages in the other eye. Controlling diabetes is important in general, and it may also be helpful for preventing retinal vein occlusion.