A sty is an acute infection of the secretory glands of the eyelids.
This common infection results from blocked glands within the eyelid. When the gland is blocked, the oil produced by the gland occasionally backs up and extrudes through the wall of the gland, forming a lump (chalazion), which can be red, painful, and nodular. Frequently, bacteria can infect the blocked gland, causing increased inflammation, pain, and redness of the eye, and even redness of the surrounding eyelid and cheek tissue. The medical term for sty is hordeolum.
The lump can point externally (outward) or internally (inward). Frequently, the lump appears with a visible whitish or yellowish spot that looks much like a large pimple. Usually, one obvious area of swelling is apparent on one lid, but many styes can appear on one or both eyelids simultaneously.
The lump frequently goes away when the blockage of the gland opening is relieved. Furthermore, the infection goes away when the pus is drained from the sty.
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- use of outdated or infected cosmetics;
- poor eyelid hygiene;
- inflammatory diseases of the eyelid, such as blepharitis, meibomitis, and rosacea;
- and hormonal changes.
Sty Symptoms and Signs
- A lump on the top or bottom eyelid
- Localized swelling of the eyelid
- Tenderness to touch
- Crusting of the eyelid margins
- Burning in the eye
- Droopiness of the eyelid
- Scratchy sensation on the eyeball
- Blurred vision
- Mucous discharge in the eye
People of all ages and both genders can develop a sty. Application of a warm compress or washcloth to the affected area for 10 minutes, four to six times a day, can speed rupture of the sty and aid in the relief of symptoms. A sty should not be pressed or squeezed to facilitate drainage. If a sty persists for several days, a doctor may lance (drain) the infection under local anesthesia.
source : emedicine.net