What is it? 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.
A sty, (hordeolum), is a small abscess of the oil gland associated with an eyelash hair follicle. It typically contains Staphylococcus aureus bacteria, however, it does not always need to be treated with antibiotics. Often hot compresses will suffice. When a sty develops, a small area of the upper or lower eyelid or the corner of the eye becomes red, tender, swollen and painful. Swelling subsides gradually becoming red, tender, swollen and painful. Swelling subsides gradually over a period of days after the pus is able to drain out. Sometimes it is necessary for your doctor to drain the hordeolum in the office.
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. It may be red or swollen initially, but eventually it forms a firm, rubbery painless lump.
Symptoms: A sty or chalazion begins as a tender red lump or bump within the eyelid at the base of the eyelash. It may cause tearing, light sensitivity and the sensation of having something in the eye. Swelling usually involves only a small area of the lid, but in some cases it can lead to irritation and redness of the whole eyelid.
Prevention: Good hygiene is the best way to prevent styes and chalazia. Keep your hands clean, don't rub your eyes, and don't share eye makeup. This is particularly important for people who have had styes or chalazia more than once.