Artery and Vein Occlusions

Retinal Artery Occlusion

Central retinal artery occlusion; Branch retinal artery occlusion; CRAO; BRAO
Last reviewed: April 15, 2010.

Retinal artery occlusion is a blockage in one of the small arteries that carry blood to the retina. The retina is a layer of tissue in the back of the eye that is able to sense light.

Causes, Incidence, and risk factors

Retinal arteries may become blocked by a blood clot or fat deposits that get stuck in the arteries. These blockages are more likely if there is hardening of the arteries (atherosclerosis) in the eye.Clots may travel from other parts of the body and block an artery in the retina. The most common sources of clots are the carotid artery in the neck and the heart.

Most clots occur in people with conditions such as:

If a branch of the retinal artery is blocked, part of the retina will not receive enough blood and oxygen. If this happens, you may lose part of your vision.

Symptoms

Sudden blurring or loss of vision may occur in:

  • All of one eye (central retinal artery occlusion or CRAO)
  • Part of one eye (branch retinal artery occlusion or BRAO)

The retinal artery occlusion may last for only a few seconds or minutes, or it may be permanent.

If the blood clot moves to another part of the brain, symptoms of a stroke may develop.

Signs & Tests

Tests to evaluate the retina may include:

General tests should include:

Tests to identify the source of a clot from another part of the body:

Treatment

There is no proven treatment for vision loss that involves the whole eye, unless it is caused by another illness that can be treated.Several treatments may be tried. These treatments must be given within 2 – 4 hours after symptoms begin to be helpful. However, the benefit of these treatments has never been proven, and they are rarely used.

  • Breathing in (inhaling) a carbon dioxide-oxygen mixture. This treatment causes the arteries of the retina to widen (dilate).
  • Massage of the eye
  • The clot-busting drug, tissue plasminogen activator (tPA)

The healthcare provider should look for the cause of the blockage. Blockages may be signs of a life-threatening medical problem.

Prognosis

People with blockages of the retinal artery may not get their vision back.

Complications

  • Partial or complete loss of vision in the affected eye
  • Stroke (due to the same factors that contribute to retinal artery occlusion, not due to the occlusion itself)

Prevention

Measures used to prevent other blood vessel (vascular) diseases, such as coronary artery disease, may decrease the risk of retinal artery occlusion. These include:

  • Eating a low-fat diet
  • Exercising
  • Stopping smoking
  • Losing weight if you are overweight

Sometimes blood thinners may be used to prevent the artery from becoming blocked again. Aspirin or other anti-clotting drugs are used if the problem is in the carotid arteries. Warfarin or other more potent blood thinners are used if the problem is in the heart.
Adapted from Pubmedhealth

Retinal Vein Occlusions

Central retinal vein occlusion

Central retinal vein occlusion; Branch retinal vein occlusion; CRVO; BRVO
Last reviewed: May 7, 2010.

Retinal vein occlusion is a blockage of the small 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.

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 veins 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.

Risk factors for retinal vein occlusion include:

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

Symptoms

  • Sudden blurring or vision loss in all or part of one eye

Signs and tests

Tests to evaluate for vein occlusion include:

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 (in patients under age 40)

The healthcare provider should closely monitor any blockage for several months. Many harmful effects, such as glaucoma, take 3 or more months to develop after the occlusion.

Treatment

Many people will regain vision, even without treatment. However, vision rarely returns to normal. There is no way to reverse or open the blockage.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. Some patients may receive 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 may block the growth of new blood vessels that can cause glaucoma. This treatment is still being studied.
  • Laser treatment to prevent the growth of new, abnormal blood vessels that leads to glaucoma

Prognosis

The outcome varies. Patients with retinal vein occlusion often regain useful vision.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.

Complications

  • Glaucoma
  • 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.

Adapted from Pubmedhealth