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.
Arcus senilis
Limbus sign
Crepitus
Limbal ring
Pachyonychia congenita
Tinea imbricata
Lichen striatus
Dolichonychia