Arcus senilis

Arcus senilis (AS), also known as gerontoxon, arcus lipoides, arcus corneae, corneal arcus, arcus adiposus, or arcus cornealis, are rings in the peripheral cornea. It‘s usually caused by cholesterol deposits, so it may be a sign of high cholesterol. It is the most common peripheral corneal opacity, and is usually found in the elderly where it is considered a benign condition. When AS is found in patients less than 50 years old it is termed arcus juvenilis. The finding of arcus juvenilis in combination with hyperlipidemia in younger men represents an increased risk for cardiovascular disease. AS is caused by leakage of lipoproteins from limbal capillaries into the corneal stroma. Deposits have been found to consist mostly of low-density lipoprotein (LDL). Deposition of lipids into the cornea begins at the superior and inferior aspects, and progresses to encircle the entire peripheral cornea. The interior border of AS has a diffuse appearance, while the exterior border is well demarcated. The clear space between the exterior border and the limbus is called the interval of vogt. Bilateral AS is a benign finding in the elderly, but it can be associated with hyperlipidemia in patients less than 50 years old. Bilateral AS may also be caused by increased levels of free fatty acids in the circulation secondary to alcohol use. Unilateral AS can be associated with contralateral carotid artery stenosis or decreased intraocular pressure in the affected eye. As these are serious medical conditions, unilateral AS should be examined by a physician. AS is usually diagnosed through visual inspection by an ophthalmologist or optometrist using a slit lamp. Several conditions can have a similar color and appearance. Limbus sign is caused by dystrophic calcification at the corneal limbus, and can be confused with AS in geriatric populations. Anterior embryotoxon is a congenital widening of the corneal limbus. Posterior embryotoxon is a congenital thickening and anterior displacement of schwalbe's line.