Also called a hordeolum, a stye is a small painful lump on the inner or outer surface of the eyelid. It can be caused by an infected eyelash follicle or an infection of meibomian glands, which produce part of the tear film which keeps the eye healthy and moist. A stye is usually caused by bacterial infection. Staphylococcus is a common bacterium found on theskin which in some circumstances multiplies and produces an infection. The bacterium is often found in the nose and can be easily transferred to the eye by first rubbing the nose and then the eye.