Sty

Sty
(Stye, Hordeolum)

What is a sty?

A sty (sometimes spelled stye) is a tender, painful red bump located at the base of an eyelash or on, inside, or under the eyelid. The medical term for a sty is hordeolum.

A sty results from an acute infection of the oil glands of the eyelid (meibomian glands) that occurs after these glands have become clogged. A sty also may arise from an infected hair follicle at the base of an eyelash. The bacterium Staphylococcus aureus is responsible for 90-95% of cases of styes. A sty can develop as a complication of blepharitis (inflammation of the eyelid).

The term external hordeolum has been used to refer to a sty that develops at the base of an eyelash involving a hair follicle of the eyelid, whereas the term internal hordeolum refers to a sty arising due to blocked meibomian glands in the eyelid.