A sty, also referred to as a hordeolum, is a bacterial abscess that occurs in the eyelid glands. It can form either on the inside or the outside of the eyelid, but is almost always swollen, red and painful. If your cat develops a sty in his eye, it will need to be treated to prevent the infection from spreading or becoming worse.
Apply hot water to a clean cloth. Wring out the excess water and then gently press the warm, damp cloth to the affected eye. This will help to reduce swelling and inflammation.
Keep the eye area clean. Trim any long hairs near the eye area by cutting parallel to the edge of the eyelid with a pair of blunt-nosed scissors. Frequently wipe away mucus or drainage that comes from the eye.
Contact a veterinarian if the sty persists for more than one week or if it worsens. The veterinarian will examine the cat's eye and likely prescribe a topical antibiotic ointment to be applied directly to the sty.