Advertisement -- Learn more about ads on this site.

Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

What Is It?

A sty, also called hordeolum, is a small abscess of the oil gland associated with an eyelash hair follicle. It typically contains Staphylococcus aureus bacteria, the cause of staph infections. When a sty develops, a small area of the upper or lower eyelid or the corner of the eye becomes red, tender and swollen. Swelling subsides gradually over a period of days after the sty develops an opening, and the pus is able to drain out.

A chalazion, like a sty, is a swelling within the eyelid caused by inflammation of an oil gland. A chalazion differs from a sty in that it does not contain an active bacterial infection. A chalazion is sometimes the aftereffect of a sty. It is less tender but lasts longer.

Natural oils from the eyelid's oil glands must drain through ducts out to the eyelashes. If debris blocks this normal drainage, it may cause a sty or chalazion. Sometimes, this debris accumulates because of a condition called blepharitis, a long-standing inflammation of the edges of the eyelids, with redness, thickening and scales and crusts.

Page 1 of 9     Next Page:  Styes And Chalazions Symptoms
Click here to to redeem your SparkPoints
  You will earn 3 SparkPoints
From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

You can find more great health information on the Harvard Health Publications website.