• There are two distinct types of styes: hordeolum and chalazion. Each has different causes and treatments.
• A hordeolum is a blockage of one of the sweat glands found in the skin of the lid and base of the eyelashes, or one of the small sebaceous glands found at the base of the eyelashes. Sebaceous glands secrete sebum, a waxy, oily material.
• A chalazion is a blockage of a meibomian gland, which is a special oil gland (sebaceous) unique to the eyelids. These glands form a single row in each lid, with the body of the gland located inside the eyelid, and the opening located at the rim of the lid, posterior to the lashes.

A sty is a bump that forms on or in the lower or upper eyelid as the result of a blocked gland. The word "sty" can also be spelled "stye."

Styes occur when a gland in or on the eyelid becomes plugged or blocked. This can occur if the gland's opening is obstructed by scar tissue or a foreign substance (makeup, dust), or if there is thickening of the substance produced by the gland, causing the material to flow sluggishly or not at all.

The most common risk factor is sluggish outflow of the sebum from the meibomian glands, which is commonly seen in a chronic inflammatory condition called meibomian gland dysfunction (also commonly called meibomian gland disease, meibomitis, meibomianitis, or blepharitis).

Meibomian gland dysfunction is frequently associated with acne rosacea on the cheeks and nose but can also be seen alone.

Other risks include obstruction of the gland's opening by scar tissue following infections, burns, or trauma. Foreign substances such as makeup and dust can also clog the gland's opening if not properly washed away.

Styes are not contagious.

The symptoms of a sty are

• foreign body sensation in the eye (particularly with blinking),
• eye pressure, and
• pain in the area of the bump, though often they are painless.

There may also be blurred vision if thick sebum or pus from within the sty spreads over the eye's surface.

If chronic meibomian gland dysfunction is present, dry eye symptoms are common. This is because the meibomian glands secrete an oil onto the surface of the eye to prevent the water layer of tears from evaporating too rapidly from the eye's surface between blinks. Therefore, poorly functioning meibomian glands can lead to dry eye.

Signs of a sty include

• presence of a lump or bump (like a pimple) on the edge of the eyelid,
• redness of the skin overlying the eyelid bump, and
• swelling and puffy appearance of the eyelid.

If the sty is draining material from the gland's opening, there may be thick discharge or crusty material accumulating on the lids and lashes. In some cases, the skin overlying the sty will become thinned and the thick material within the sty (pus) may ooze out through a break in the skin. Watery tears can also be produced in response to irritation and pain.

Stys can be external, meaning the blocked gland protrudes outward and appears as a visible bump under the skin, or interior, in which the blocked gland protrudes behind or under the eyelid.

Health care providers, including pediatricians and emergency medicine physicians, often diagnose and treat styes. Eye specialists, including optometrists and ophthalmologists, are called upon to treat more advanced cases such as those that appear infected or those that recur.

The health care professional will examine the lids to locate the opening of the plugged gland. This helps to distinguish between a hordeolum and a chalazion. Also, the doctor will look for signs of scar tissue, foreign bodies, and underlying chronic meibomitis.

In addition, the doctor will look for any signs that the gland may have become infected. It is particularly important to identify infection that has spread from the gland to the eye, neighboring skin, or orbit.

The best home treatment to get rid of a stye is to apply a warm water compress as often as possible. It is important to remember that a chalazion may take months to resolve completely.

A noninfected sty will resolve on its own. Warm compresses will help soften the material in the gland, allowing the gland's contents to drain naturally. Squeezing, popping, or cutting the hordeolum should be avoided as this can result in scarring.

A noninfected chalazion similarly will resolve on its own with the aid of warm compresses, though over a much longer period of time. A small chalazion may resolve within weeks, while larger ones may resolve over the course of a year. As the chalazion decreases in size, patients feel gradual relief from their symptoms.

The most conservative treatment is application of frequent warm (not too hot) compresses alone. This can be accomplished with a warm wet washcloth, microwaveable eye masks (sold at drugstores), or a plug-in electric heating pad. The key is to dedicate as much time as possible to treatment with the warm compress. Several minutes at a time (for example, 15 minutes), several times a day (for example, four times per day) will improve the odds that the sty or chalazion will clear on its own. A child may need help applying the warm compress. Be sure to check the temperature of the compress against another part of your skin, such as the back of your hand, to ensure the compress does not burn your eye or face.

An ophthalmologist can inject a steroid into the lesion, often resulting in a speedier resolution. However, this carries a small risk of bleeding/bruising, depigmentation/thinning of the skin, scar, pain, and in very rare cases, loss of vision.

Finally, the chalazion can be incised and drained. This is the most invasive method and is reserved as a last resort by most eye doctors. The eyelid is anesthetized, and a clamp is placed around the chalazion. The eyelid is everted, and the meibomian gland is incised from the back surface of the eyelid, avoiding cutting the skin on the front surface. The waxy sebum is scooped out of the gland with a special curette. This debulking of the gland's contents may be sufficient to shrink the chalazion; however, there is risk that the chalazion may recur, particularly if the underlying cause is not addressed.

If a sty appears infected, oral antibiotics may be necessary. An abscess can form in the eyelid. A culture of the material in the chalazion is sometimes obtained to identify the bacterium. Antibiotic treatment is particularly important if the bacterial infection is spreading along the skin (cellulitis) or spreading into the orbit (orbital cellulitis). Orbital cellulitis is considered an emergency, as rapidly spreading infection can be vision or life-threatening. Orbital cellulitis treatment usually requires intravenous antibiotics.

In some situations, the infection spreads to the eye itself. If conjunctivitis (pinkeye) develops, topical ophthalmic antibiotics (antibiotic ointments or drops) might be necessary.

Treatment of the underlying cause of the sty is also important to prevent recurrence.

Some eye doctors will recommend not wearing contact lenses until the sty resolves. This is especially the case if there's concern about a concurrent infection.

When a sty or chalazion clears on its own, there are rarely complications.

A steroid injection carries the complication of possible scarring of the lid, discoloration (depigmentation) of the overlying skin, infection, bleeding or bruising, and in extremely rare situations, blindness if the steroid is injected improperly.

Incision and drainage of a chalazion carries a risk of scarring or deformity of the eyelid, bleeding, or bruising.

If a sty or chalazion becomes infected, the infection can spread to the eye (conjunctivitis or corneal keratitis), skin (cellulitis), or orbit (orbital cellulitis). Prompt treatment for these complications is extremely important, and your ophthalmologist will prescribe the appropriate antibiotics when indicated.

Very rarely, a chronic, recurring chalazion is a sign of a cancer in the eyelid. An ophthalmologist will look for signs of malignancy and obtain a biopsy of one is suspected.

A hordeolum may resolve in a few days, while a chalazion may take months. Both types of styes should resolve completely once the plugged gland drains. If an infection sets in, treatment will be necessary.

Recurrence is likely if chronic underlying conditions aren't addressed. In the case of meibomitis, your eye doctor will likely recommend daily cleansing of the eyelids and eyelashes with a gentle soap (such as baby shampoo). Increased intake of omega-3 fatty acids in the diet or from supplements may also help improve the flow of the sebum. Small doses of oral doxycycline are prescribed for acne rosacea and meibomitis in some patients.

The best prevention is to keep the eyelids and eyelashes clean. This can be done with daily diluted baby shampoo lid scrubs while in the shower or use of eyelid cleansing pads available at drug stores. Many people benefit from daily warm compresses.

A diet high in omega-3 fatty acids (for example, fish or flaxseeds) and vegetables is believed to have an anti-inflammatory effect and is associated with improvement of meibomian gland function and better eye health in general.

Ask your ophthalmologist for advice about the use of preventative antibiotics. For example, in adults with chronic recurring chalazions, low-dose oral doxycycline may help meibomian gland dysfunction, but doxycycline should be avoided in children and women of child-bearing age.

A device undergoing clinical trials that warms the lids and expresses thickened oils may also help alleviate chronically clogged oil glands.