Meibomian glands are found in the eyelids, with about 25 to 40 in the upper lid and 20 to 30 in the lower lid. Their job is to secrete oil onto the surface of the eye, keeping your tears from evaporating. However, if they malfunction, the result is meibomian gland dysfunction (MGD), otherwise known as the leading cause of dry eye syndrome.
A malfunctioning meibomian gland causes a reduction in the quantity or quality of oil in the outer layer of the tear film, leading to Dry Eye, Chalazia, or other lid margin infections.