Arcus senilis is a grayish-blue to white opaque band in the periphery of the cornea, which is the clear window-like structure on the front of the eye. The number of people with arcus senilis increases with age for both genders, with the problem occurring more frequently in men than in women. Cholesterol crystals, or fats, deposit in the central layer of the cornea, coalescing into the ring-shaped structure. Arcus deposits initially appear at the six and 12 o’clock positions of the cornea and expand circumferentially to form the entire ring. A thin, clear zone between the ring and the corneal edge is called the lucid interval of Vogt.
More than two-thirds of men and women in the eighth decade of life have this condition. Women rarely develop arcus prior to menopause. The condition is more common in patients of African descent than in Caucasians. In addition, corneal arcus is often present in smokers, hypertensive patients, and diabetics.
Although arcus may occur in the absence of medical conditions, the presence of arcus senilis can be an indicator of high cholesterol or high blood lipid levels. In most of the corneal arcus patients over the age of 40, the blood cholesterol levels are normal. If an individual under the age of 40 has arcus senilis, it is more likely to point to elevated cholesterol levels. Affected young people with the condition usually have a significant family history of high cholesterol and early heart disease. Arcus in a young person is called arcus juvenilis.
When arcus senilis only affects one eye, it can be a sign of reduced blood flow to the uninvolved eye. This may be indicative of obstruction or calcification of a carotid artery. Sturge-Weber syndrome, a condition associated with a one-sided facial port wine stain and increased eye pressure, can also lead to the development of a unilateral arcus on the uninvolved side. Scientists postulate that the facial blood vessel tumor increases the pressure in the eye, thereby decreasing the blood flow through the eye. The decreased blood flow from either carotid artery occlusion or Sturge-Weber has a protective effect against the deposition of cholesterol in the cornea.
The finding of arcus senilis in patients younger than 40 requires prompt blood work to evaluate the possibility of lipid abnormalities in the body. Other signs and symptoms of excessively high blood lipids include fatty deposits on the eyelids, called xanthelasma, and fatty deposits in the skin, called xanthomas. The condition, although usually asymptomatic, may also cause chest pain, abdominal pain, and enlargement of the spleen and liver.