corneal arcus

cor·ne·al ar·cus

(kōrnē-ăl ahrkŭs) A thin, whitish circle around the iris; normal finding in old people.
Synonym(s): arcus senilis.

corneal arcus 

A greyish-white ring (or part of a ring) opacity occurring in the periphery of the cornea, in middle and old age. It is due to a lipid infiltration of the corneal stroma. With age the condition progresses to form a complete ring. That ring is separated from the limbus by a zone of clear cornea. The condition can also appear in early or middle life and is referred to as arcus juvenilis (or anterior embryotoxon); it is somewhat whiter than corneal arcus. Arcus juvenilis is often associated with heart disease in men (Fig. C19). Syn. arcus senilis; gerontoxon. See marginal furrow." >Fig. C19 Advanced corneal arcus