Arcus senilis is a half-circle of gray, white, or yellow deposits in the outer edge of your cornea, the clear outer layer on the front of your eye. It’s made of fat and cholesterol deposits.

In older adults, arcus senilis is common and is usually caused by aging. In younger people, it may be related to high cholesterol levels.

Arcus senilis is sometimes called corneal arcus.

Arcus senilis is caused by deposits of fat (lipids) in the outer part of your cornea. Cholesterol and triglycerides are two types of fats in your blood. Some of the lipids in your blood come from foods you eat, such as meat and dairy products. Your liver produces the rest.

Just because you have a ring around your cornea, it doesn’t necessarily mean you have high cholesterol. Arcus senilis is very common as people get older. This is likely because blood vessels in your eyes become more open with age and allow more cholesterol and other fats to leak into the cornea.

About 60 percent of people ages 50 to 60 have this condition. After age 80, almost 100 percent of people will develop this arc around their cornea.

Arcus senilis is more common in men than in women. African-Americans are more likely to get this condition than are people of other ethnic groups.

In people under age 40, arcus senilis is often due to an inherited condition that raises cholesterol and triglyceride levels.

In rare cases, children are born with arcus senilis. In younger people, the condition is sometimes called arcus juvenilis.

Arcus senilis can also appear in people with Schnyder central crystalline dystrophy. This rare, inherited condition causes cholesterol crystals to deposit on the cornea.

If you have arcus senilis, you’ll notice a white or gray half-circle both on the upper and lower areas of your cornea. The half-circle will have a sharp outer border and a fuzzy inner border. The lines may eventually fill in to form a complete circle around your iris, which is the colored part of your eye.

You likely won’t have any other symptoms. The circle shouldn’t affect your vision.

You don’t need to treat this condition. However, your doctor might recommend that you have your levels checked.

If you’re under age 40 and have arcus senilis, you should get a blood test to check your cholesterol and lipid levels. You may be at higher risk for high cholesterol and coronary artery disease.

Your doctor can treat high cholesterol in a few ways. You might start by trying lifestyle changes, such as exercising more and eating foods low in saturated fat, trans fat, and cholesterol.

If diet and exercise aren’t enough, several medications can help lower your lipid levels:

  • Statin drugs block a substance your liver uses to make cholesterol. These drugs include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Altoprev), pravastatin (Pravachol), and rosuvastatin (Crestor).
  • Bile acid binding resins force your liver to use more cholesterol to produce digestive substances called bile acids. This leaves less cholesterol in your blood. These drugs include cholestyramine (Prevalite), colesevelam (Welchol), and colestipol (Colestid).
  • Cholesterol absorption inhibitors like ezetimibe (Zetia) reduce your body’s absorption of cholesterol.

Drugs may be used to lower triglyceride levels:

  • Fibrates reduce production of lipids in your liver and increase the removal of triglycerides from your blood. They include fenofibrate (Fenoglide, TriCor) and gemfibrozil (Lopid).
  • Niacin reduces the production of lipids by your liver.

The relationship between arcus senilis and abnormal cholesterol levels in older adults has been controversial. Some studies say this condition is linked to cholesterol problems and cardiovascular disease in older adults. Other studies say arcus senilis is a normal sign of aging, and is not a marker for heart risks.

When arcus senilis starts before age 45, it’s often due to a condition called familial hyperlipidemia. This genetic form is passed down through families. People with this condition have abnormally high levels of cholesterol or triglycerides in their blood. They are at higher risk for heart disease.

Arcus senilis itself doesn’t cause complications, but the very high cholesterol that causes it in some people can increase heart risks. If you develop this condition before your 40s, you may be at high risk for coronary artery disease or cardiovascular disease.

Arcus senilis shouldn’t affect your vision. However, if you have it — especially if you’re diagnosed before age 40 — you may be at increased risk for coronary artery disease. Lowering your cholesterol level with diet, exercise, and medication can reduce your heart disease risks.