The term chalazion (pronounced chah la' ze on) is derived from the Greek word meaning small lump. It refers to a cystic swelling with chronic inflammation in an eyelid. A gradual enlargement can be felt near the margin of the lid due to the swelling in one of the eyelid oil glands (meibomian).

A stye usually starts as a sensitive, red, swollen area on the surface of the eyelid along the eyelash line. This changes into a small, tender bump similar to an acne pimple. The eye may water, and the eyelid may be painful. Typically the stye comes to a head (clear or yellow fluid collects in the stye) and breaks open within about 3 days. After the stye opens, it usually heals and goes away. See an illustration of a stye .