The swelling of a sebaceous gland in the eyelid.
A meibomian cyst results from the blockage of a meibomian gland. These glands, similar to skin’s sebaceous glands, are located on the inner side of the eyelids and have openings at the eyelid edges. When inflamed and enlarged, they resemble styes. However, while a stye appears in an eyelash follicle at the edge of the eyelid, a meibomian cyst is within the eyelid’s substance and is visible only when the eyelid is turned inside out.