Meibomian gland

The meibomian glands (or tarsal glands) are a special kind of sebaceous glands at the rim of the eyelids, responsible for the supply of sebum, an oily substance that prevents evaporation of the eye's tear film, prevents tear spillage onto the cheek, and makes the closed lids airtight. There are approximately 50 glands on the upper eyelids and 25 glands on the lower eyelids. The glands are named after Heinrich Meibom (1638-1700), a German physician.

Proteins
In humans, more than 90 different proteins have been identified in meibomian gland secretions.

Dysfunction
Dysfunctional meibomian glands often cause dry eyes, one of the more common eye conditions. They may also cause blepharitis, as the dry eyeball rubs off small pieces of skin from the eyelid, which can get infected. Inflammation of the meibomian glands (also known as meibomitis, meibomian gland dysfunction, or posterior blepharitis ) causes the glands to be obstructed by thick secretions, the resulting swelling is termed a chalazion. Besides leading to dry eyes, the obstructions can be degraded by bacterial lipases, resulting in the formation of free fatty acids, which irritate the eyes and sometimes cause punctate keratitis.