STY

also called hordeolum in medicine, infection of an eyelid gland. Two types are distinguished, the external and the internal sty. The external sty is an infection, usually with staphylococcus organisms, of a sebaceous gland in the margin of the eyelid. The eye becomes sensitive to light, tears flow copiously, and there is a sensation of a foreign body in the eye. The area of infection is first reddened and then swollen like a pimple or small boil, with a yellow spot in the centre. The breaking of the sty and the discharge of its contents are hastened by application of warm compresses. An internal sty is a staphylococcic infection of a meibomian gland, one of the modified sebaceous glands that lie close under the lining of the eyelids. These infections are more painful than is the external sty because they are pressed between the eyeball and the fibrous platecalled the tarsal platein the lid. The internal sty usually breaks through the lining of the lid, rather than the outer skin, when it discharges. This type of sty is sometimes called a chalazion, although the latter term is usually reserved for a painless swelling of the meibomian gland. This swelling is a cyst a liquid- or semisolid-filled sacthat is granulomatous; that is, composed of young scar tissue. It sometimes appears without apparent cause and sometimes as an aftereffect of an internal sty.