KERATITIS

inflammation of the cornea, the transparent portion of the eyeball that is in front of the iris and pupil. There are several varieties. Often there is inflammation of both the cornea and the conjunctiva, the mucous membrane that lines the eyelid and covers the white of the eye. Two types of keratitis result from dryness of the cornea. One of these, keratitis sicca, also called Sjgren's syndrome (q.v.), or keratoconjunctivitis sicca, is dryness and inflammation of the cornea and conjunctiva resulting from a failure to secrete sufficient tears. The cornea may also become dry and inflamed when, because of protrusion of the eyeball or paralysis of the muscle that closes the lids, a person is unable to shut his eyes completely. This condition is called lagophthalmic (hare-eyed) keratitis because of the ancient belief that hares are unable to close their eyes. Keratitis leading to the spread of blood vessels into the corneal area and even to blindness from a completely opaque cornea can result from chemical burns, particularly burns from acids and alkalis. Early flooding of the eye with water, either slightly salted or straight from the tap, is standard procedure, since the extent of the damage depends in large part upon the length of time that the chemical remains in the eye. The most serious chemical burns are caused by alkali, which, if not quickly removed, can do progressive damage over periods of months or years. Interstitial keratitis, an inflammation deep in the cornea, may be caused by congenital syphilis, by tuberculosis organisms, by the virus of herpes zoster, or even by physical injury to the eye. Affected persons are usually children whose eyes are painful, tend to water, and are sensitive to light. Treatment is of the underlying disease. In dendritic (branching) keratitis, or dendritic ulcer, the cornea is inflamed by infection with the herpes simplex, or cold sore, virus. The lesions, as the name suggests, follow branching lines, along which minute blisters may form and break, leaving raw areas. Often the cornea becomes insensitive, so that the process may not be painful. Rosacea keratitis is a complication of acne rosacea, a disease in which the skin of the face is affected first by pronounced flushing and later by the formation of nodules and pustules. The keratitis causes severe pain and corneal scarring with impairment of vision. Neuroparalytic keratitis is inflammation of the cornea as a sequel to interruption of sensory impulses over the fifth cranial (trigeminal) nerve. The cornea's loss of sensitivity leaves it much more subject to injury and infection. This type of keratitis tends to lead to ulceration of the cornea, the collection of pus in the anterior chamber of the eye (a condition called hypopyon), and the impairment of vision, and may result in perforation of the eyeball, with consequent loss of that eye. Treatment includes the intensive use of antibiotics.