The cornea and disorders of lipid metabolism.

Disorders of lipid metabolism, either hyperlipidemia or hypolipidemia, are associated with the formation of corneal opacities. Corneal arcus, the most commonly encountered peripheral corneal opacity, is frequently associated with abnormal serum lipid levels, but may occur without any predisposing factors. Reports also have linked corneal arcus with alcoholism, diabetes mellitus and atherosclerotic heart disease. Unilateral arcus is a rare entity that is associated with carotid artery disease or ocular hypotony. Diffuse corneal opacities associated with hypolipidemic disorders such as LCAT deficiency, fish eye disease and Tangier disease, may be the initial manifestation of these disorders and puts the ophthalmologist in a position to make an early diagnosis. Corneal arcus, along with a central corneal opacity, is seen in Schnyder's crystalline stromal distrophy. The association of the disorder with a dyslipidemia remains controversial. A review of lipid metabolism, corneal arcus and several disorders of lipid metabolism that affect the cornea are presented.