an opaque, grayish ring at the periphery of the cornea just within the sclerocorneal junction, of frequent occurrence in the aged; it results from a deposit of fatty granules in, or hyaline degeneration of, the lamellae and cells of the cornea. Syn: anterior embryotoxon, arcus adiposus, arcus juvenilis, arcus lipoides, arcus senilis, gerontoxon, linea corneae senilis, lipoidosis corneae.