The eyelid has several glands which produce components of the tear film in front of the eye. The tears that cover and protect our eyes are not just water, but a mix of a lipid layer, an aqueous (or watery), layer and a mucin layer. Some of the glands that produce the lipid layer are located in the eyelids. The produce a lipid secretion that travels down a tube in the upper eyelid, and up a tube in the lower eyelid to empty just behind the row of eyelashes. You can see these holes if you look closely at your eyelid in a high magnification mirror. As you might suspect, excessive makeup can sometimes plug these holes causing the secretions to "back up" and form a lump. While makeup can be an issue, sometimes people just have an occasional chalazion, or stye, and it resolves on its own without any clear reason as to why they got it. Blepharitis or inflammation on eyelid margin can sometimes contribute to this as well. I get asked daily from patients, "Why did I get this chalazion?"
The answer isn't quite clear as to why certain people get chalazia and certain people don't. Sometimes people get a chalazion, or a few chalazia, during hormonal changes, such as during puberty or pregnancy, then they never have them occur again. Sometimes it is just plan bad luck, like getting a pimple at an inconvenient time. With chronic eyelid inflammation, chalazia can can occur more frequently. A chalazion is a benign lesion on the eyelid that is treated regularly by oculoplastic surgeons.
The first line of treatment for a new chalazion is the same as the regimen for preventing new chalazia--warm compresses. Heat and vertically oriented (top to bottom in the upper eyelid, bottom to top in the lower eyelid) compresses cause secretion pathway to expand and drain. This doesn't always work but it is the first and most conservative step in treating a chalazion. The next level of treatment when warm compresses do not help resolve the chalazion is steroid injection. This is generally useful for the type of chalazion that is red and mildly inflamed but doesn't really have a discrete lump. The third and final treatment is incision and excision of the chalazion. Often this involves everting the eyelid with a chalazion clamp after local anesthesia, and excising the chalazion with a fine incision and removing the surrounding pseudo- capsule that may have formed with chronic inflammation. I prefer to also place steroid at the time of chalazion excision to give it the highest probability of not recurring.