A stye, or external hordeolum, is an infection of one or more sebaceous glands located at the base of the eyelashes. It is characterised by a small, red and painful lump often containing pus and visible on the external surface of the eyelid. The most common symptoms of a stye include itching sensation, sensitivity to light, tenderness of the eyelid, swelling, redness and tearing of the eye. Styes often respond to antibiotic therapy and complete resolution is typical. Occasionally, it is necessary to drain the stye to hasten the healing process.