A common eye disorder, a chalazion is a granulomatous inflammation of a meibomian gland in the upper or lower eyelid. This disorder is characterized by localized swelling and usually develops slowly over several weeks.

A chalazion may become large enough to press on the eyeball, producing astigmatism; a large chalazion seldom subsides spontaneously and may have to be incised and curetted surgically. A person susceptible to developing chalazia may have more than one because the upper and lower eyelids contain many meibomian glands. If a chalazion becomes persistent and chronic, a neoplasm should be ruled out by biopsy.