Arcus senilis (corneal arcus) is a disease of the cornea which sometimes appears as an opaque, grayish arc at the periphery of the cornea just within the sclerocorneal junction. Eventually, the arc may evolve into a complete ring around the cornea. The arcs are due to abnormal deposits of phospholipids and cholesterol. It is usually caused by high blood lipid levels or eye defects. Arcus senilis doesn’t affect vision, nor does it require treatment.