Sty (Stye): A stye (sty) is an infection of the eyelid, resulting from a blocked oil gland. Seborrhea, improper eye makeup removal, use of infected cosmetics, poor eyelid hygiene, stress, hormonal changes, and Blepharitis, rosacea, and meibomitis may cause styes. Symptoms include a lump on the eyelid, swelling, pain, redness, tenderness, blurred vision, pus, and a scratchy sensation on the eyeball. Treatment may involve warm compresses, scrubbing the eyelid with a mild soap, and discontinuing wearing contact lenses and eye makeup.