a deposit of cholesterol on the eyelid.
another possibility is xanthelasma, which are localized deposits of fats that collect in the skin of the upper and lower eyelids. they can be skin-colored to yellowish and are associated about half the time with elevated blood lipids (fats), including cholesterol and triglycerides, which may be a sign of diabetes. removal usually requires electric cautery or surgery. everydayhealth.com
xanthelasma: tiny (1-2 mm) yellowish plaques that are slightly raised on the skin surface of the upper or lower eyelids. xanthelasma is caused by tiny deposits of fat in the skin and is often associated with abnormal blood fat levels (hyperlipidemia). xanthelasma is a harmless growth of tissue. xanthelasma typically appears in or near the eyelids. medicinenet.com
high levels of ldl can cause arcus corneae and tendinous xanthomas at the achilles, elbow, and knee tendons and over metacarpophalangeal joints. other clinical findings that occur in patients with high ldl (eg, in familial hypercholesterolemia) include xanthelasma (lipid rich yellow plaques on the medial eyelids). xanthelasma can also occur in patients with primary biliary cirrhosis and normal lipid levels. merckmanuals.com