A sty (stye) is an infection of the oil gland at the base of an eyelash. It is a tender, painful red bump located at the base of an eyelash or inside the eyelid. It appears as a red, raised pimple on the edge of the eyelid. Symptoms of a sty can be pain, tenderness, redness, and swelling with a small pustule. The eyeball itself may feel irritated or as if something is scratching it due to the swelling of the eyelid.
Treatment for a sty includes warm compresses applied to the affected area for 10 minutes, up to six times daily. If the sty comes to a head and releases pus, it should be cleaned gently with soap and water. A sty should not be pressed or squeezed to facilitate drainage. If a sty persists for several days, a doctor may lance (drain) the infection under local anesthesia. If the sty is very large, painful, or affects your vision, see your doctor.
Chalazion (Eyelid Cyst): A chalazion (meibomian cyst, tarsal cyst, or conjunctival granuloma) is a lump in the upper or lower eyelid caused by obstruction and inflammation of an oil gland of the eyelid. Eyelid glands are called the meibomian glands The gland opening becomes clogged and the gland swells.
Treatment: Chalazia are treated with warm compresses, though in rare cases they may require antibiotics. If the chalazion becomes severe, causes changes in vision, or is persistent, it may be removed surgically.