In this condition factsheet:
The Facts on Styes
Styes are minor, short-term bacterial infections affecting the edge of the eyelid or eye. A stye is also called a hordeolum.
Glands around the edge of the eyelid get clogged and swell until a sore like a small pimple or boil appears. It may also be due to a blockage in a follicle of an eyelash. The sore causes eye pain and becomes temporarily filled with pus. A second, more serious type of stye can develop deeper inside the eyelid and swell until it needs the attention of a doctor.
Styes are the most common type of eyelid infection. The average person has a good chance of having one or two styes in their lifetime, though some people develop them repeatedly. They can be annoying and painful but are usually not serious.
Causes of Styes
There are actually two distinct types of stye. Both are usually caused by a bacterium known as staphylococcus, or "staph" for short. It's a common bacterium on your skin that can over-reproduce and start infections.
When it causes the type of ordinary stye called an external hordeolum, it begins by infecting an eyelash at the root (the follicle), unleashing a process that results in swelling. This kind of stye can also start from a staph infection in an area close to the follicles called the glands of Moll and Zeiss. When the stye swells and begins to infect or clog other glands around the eyelid, it causes pain and discomfort. At this point, you may often see and feel a nodule, a small pimple-like reddish abscess that begins to fill with pus. Styes often occur in people who have a lowered immune resistance due to conditions such as diabetes, or have a local predisposition such as acne.
Not all styes are visible. A stye that forms beneath the surface of the eyelid will hurt, but it may never develop an external nodule. Styes form most commonly in the upper eyelid near the eyelashes, but can develop on the lower eyelid as well. Usually, only a small area of the eyelid swells, but the entire lid may occasionally become inflamed.
The second kind of stye, the internal hordeolum, is a more serious form of staph infection. It originates in a gland called the meibomian beneath the surface of the middle of the eyelid. Because it's buried in the central part of the eyelid, an internal hordeolum is more painful than the external kind. While the pus in an external stye will usually drain on its own, an internal one won't. The person will most likely have to visit a doctor to have it opened and drained.
Both external and internal styes are not contagious, and are never a sign of cancer.
Symptoms and Complications of Styes
Symptoms of styes include redness, swelling, pain, or tenderness in part of the eye. These sensations are usually accompanied by slightly blurred vision, a teary sensation, and the feeling of something in the eye. An external stye can be easily verified by finding the nodule on the eyelid. Sometimes, people with internal stye experience fever or chills.
People generally get a single stye at a time. Some people get more than one stye at a time. A few suffer from the condition chronically and have repeated infections. The staph infection that starts styes can sometimes expand quickly and infect many eyelash follicles, which then swell in larger numbers. Or it can spread infection to the tissue of the eye. A stye that grows rapidly like this or opens to drain pus into the eye needs medical attention. People with recurring styes can also develop a chronic eyelid infection called staph blepharitis.