This is the term applied to an affection of the cornea which manifests itself as a silvery rim near the edge of the cornea but separated from the edge by a ring of transparent tissue. It is due to fatty degeneration of the tissue of the cornea, and is considered to be an indication of the beginning of similar changes in other parts of the body, particularly in the blood-vessels of the brain. It is seen most frequently in persons over fifty years of age, though it may occur at an earlier period, especially in persons addicted to the use of alcoholic drinks.