A stye is caused by infection of a gland at the base of an eyelash. It generally causes a lump at the margin of the eyelid, that is inflamed and often painful. Styes are usually caused by ...

Source: Focus Medica. A small red, painful lump in the edge of the eyelid. Stye is usually caused by bacterial infection. It may be present inside or outside the eyelid on one or both eyes and is ...