A sty  (sometimes spelled stye) is a tender, painful red bump located at the base of an eyelash or inside the eyelid. A sty results from an acute infection of the oil glands of the eyelid that occurs after these glands have become clogged. A sty also may arise from an infected hair follicle at the base of an eyelash. Symptoms are generally redness, tenderness, and pain in the affected area. The eye may feel irritated or "scratchy." Later symptoms can include swelling, discomfort during blinking, watering of the eye, and light sensitivity. A common sign of a sty is a small, yellowish spot at the center of the bump that develops as pus expands in the area. People of all ages and both genders can develop a sty. Application of a warm compress  or washcloth to the affected area for 10 minutes, four to six times a day, can  speed rupture of the sty and aid in the relief of symptoms. 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.

 
A chalazion is a tiny lump of the upper or lower eyelid caused by inflammation of a gland of the lid. It may be soft and fluid-filled or firmer. A chalazion is also referred to as a meibomian cyst, tarsal cyst, or conjunctival granuloma. The narrow opening through which a meibomian gland secretes its material can become clogged from narrowing of the opening or hardening of the sebaceous liquid near the opening. If this occurs, the gland will have a backup of the material it secretes and it will swell. Most chalazions are treated with warm compresses to the eyelid to promote healing and circulation of blood to the inflamed area. Doctors may prescribe an antibiotic drop or ointment to be used immediately after the compresses. If the chalazion persists and is causing an unsightly lump, it can be removed surgically through the inside of the lid.