A chalazion is a small bump in the eyelid caused by a blockage of a tiny oil gland.
Meibomian gland lipogranuloma
Causes, incidence, and risk factors
A chalazion develops in the glands that produce the fluid that lubricates the eye. These are called Meibomian glands. The eyelid has approximately 100 of these glands, which are located near the eyelashes.
A chalazion is caused by a blockage of the duct that drains one of these glands.