Two common conditions that affect your eyelids are chalazia and styes. These blockages trap the oil produced by the glands and cause a lump on the eyelid that is usually about the size of a pea. These are usually relatively painless. If the chalazion becomes infected, the eyelid can become swollen, inflamed and more painful. Styes are often confused with chalazia.
Styes are infections or abscesses of an eyelid gland near an eyelash root or follicle.
They generally occur nearer to the edge, or margin of the eyelid than do chalazia, where they form a red, sore lump similar to a boil or pimple. In some cases, both chalazia and styes may come to a head and drain on their own without treatment. However, in most instances, they do not. In some cases, steroid drugs may be injected into or adjacent to the site of the chalazion. A chalazion may also be treated by surgical incision and drainage when necessary.