A sty (sometimes spelled stye) is a tender, painful red bump located at the base of an eyelash or under or inside the eyelid. The medical term for a sty ishordeolum (plural, hordeola).
A sty results from an infection of the oil glands of the eyelid (meibomian glands) that help to lubricate the eyeball. The infection occurs after these glands have become clogged. A sty also may arise from an infected hair follicle at the base of an eyelash. The bacteriumStaphylococcus aureus that frequently is found on the skin is responsible for 90%-95% of cases of styes. A sty can develop as a complication of diffuse inflammation of the eyelid (blepharitis).
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 terminternal hordeolum refers to a sty arising due to an inflamed meibomian gland under the eyelid.
A sty is sometimes confused with a chalazion (see below), which is a cyst or a specific type of scarring (due to chronic inflammation) arising in the meibomian glands of the eyelid. In contrast to a sty, a chalazion is usually painless.
Styes are usually caused by obstructed orifices (or openings) of the oil glands in the eyelid. Very frequently, they are infected by bacteria, most commonly Staphylococcus bacteria.
Seborrhea (excessive oily discharge from the glands) may increase the likelihood of developing one of these infections. Certain factors can contribute to the blockage of the glands:
- improper or incomplete removal of eye makeup;
- use of outdated or infected cosmetics;
- inflammatory diseases of the eyelid, such as blepharitis, meibomitis, and rosacea;
Application of a warm compress or warm washcloth to the affected area for 10 minutes, four to six times a day, can be an effective home remedy and speed rupture of the sty that aids in the relief of symptoms. A sty should not be pressed or squeezed to facilitate drainage, since this can spread or worsen the infection. If a sty persists for several days, a doctor may lance (drain) the infection under local anesthesia in his or her office.
Children who require surgical drainage of a sty may need a general anesthetic. Antibiotic ointments and/or steroid ointments sometimes are prescribed to treat a sty. Rarely, systemic (oral) antibiotics are recommended for persistent or multiple styes. Over-the-counter pain medications may be used to alleviate pain and tenderness. Contact lenses and eye makeup should never be worn during treatment for a sty.
What is the prognosis (outcome) of a sty?
A sty is harmless in the majority of cases. In most cases, a sty ruptures on its own within a few days to a week, leading to relief from symptoms. Some people will require medical or surgical treatment of a sty, as with complications described in the following section. A sty does not cause intraocular damage (damage to the eye). Styes often recur, but complications of styes are rare (see below).
Are there any potential complications resulting from a sty?
Complications of a sty are rare. The infection may spread to other eyelash follicles, leading to multiple styes. A chalazion (a form of scarring of the glands in the eyelid that may include the formation of cysts) is the most common complication that develops from a sty. Chalazia can be large enough to deform the cornea of the eye and interfere with vision, and they may cause a cosmetic problem.
Other potential complications include a generalized infection (cellulitis or blepharitis) of the eyelid, and improper drainage of a sty may lead to deformity or disruption of growth of eyelashes. Progression of a sty to a systemic infection (spreading throughout the body) is extremely rare, and only a few instances of such spread have been recorded.
Can a sty be prevented?
While it is impossible to completely prevent the development of a sty, good hygienic practices, including proper hand washing, can help prevent all forms of infection, including a sty.
Other measures that can help prevent styes include
- never sharing cosmetics or cosmetic eye tools (such as lash curlers or eyelash combs) with others,
- keeping eye tools clean,
- discarding old or contaminated eye makeup,
- keeping all cosmetics clean,
- not touching the eye and surrounding areas.