What exactly is an eye sty? Another name for eye sty is hordeolum; it is an abscess of the oil gland that is around a hair follicle on either the top or bottom eyelid.
The bacterium Staphylococcus aureus is responsible for 90-95% of cases of eye styes. An eye sty can develop as a complication of blepharitis (inflammation of the eyelid).
The first sign of an eye sty is generally redness. Within hours you will have tenderness, and pain in the affected area. The eye may feel irritated or "scratchy". Later symptoms can include swelling, discomfort during blinking of the eye, watering of the eye, and sensitivity to light. A common sign of an eye sty is a small, yellowish spot at the center of the bump that develops as pus expands in the area.