A stye, also called a hordeolum, is a lump or pimple on the eyelid edge which represents an infection of an oil or mucous-secreting gland. A chalazion is a small lump on the inner or outer surface of the eyelid. It is caused by an inflammatory reaction to material trapped inside an oil-secreting gland in the eyelid. The diagnosis can usually be made during a simple examination of the eyelids.
A chalazion or stye can develop when an eyelid gland becomes blocked. Chalazia vary in size from being barely noticeable to as large as a pea. They are often characterized by a red, swollen area of the eyelid, being sometimes tender, which eventually changes to a painless, slowly growing round mass in the lid.
A sty usually goes away in a week or two. Chalazia generally take longer, disappearing after a month or longer. Chalazia and styes are common and can usually be treated successfully, if necessary.
If you frequently develop a chalazion or stye, be sure to tell your doctor. There may be steps you can take to slow their recurrence. These steps have to do with keeping the eyes clean.