Eyelid

Structure

Each eyelid contains thin skin, a layer of orbicularis oculi muscle, a stiff tarsal plate, and conjunctiva on its inner surface. Meibomian glands in the tarsal plate secrete the oily layer of the tear film.

Function

Blinking, which happens about fifteen times per minute, sweeps tears across the cornea and prevents the eye from drying out. The upper eyelid is the more active of the two.

Clinical note

A blocked meibomian gland can form a painless lump called a chalazion, while inflammation of the lid margin is called blepharitis.