XEROTIC KERATITIS begins with dry ness of the conjunctiva; and a general haziness of the cornea, which soon leads to ulceration, perforation, and loss of the eye. Both eyes are generally affected; the disease occurs in feeble infants that rarely survive.
Diagnosis.—Keratitis is recognized by careful inspection of the cornea under the proper conditions of illumination. Slight opacity is rendered most evident by strong oblique illumination which should be so arranged that the light will be concentrated upon the cornea, while the iris behind it is left in comparative shadow, to furnish a dark background. Localized points of opacity in front of the pupil may also be studied with the _ophthalmoscope, using the strongest con vex lens behind the mirror, and looking from about the focal distance of the lens in front of the eye. Ulceration is best discovered by placing the patient where the light from a large window will be reflected from the surface of the cornea, snch a reflex showing all the irregulari ties of the reflecting surface. To make sure that these irregularities arc not filled in with mueus, that may render them invisible, it is well to wipe the sur face with a pledget of cotton. Or to outline an ulcer more distinctly for treat ment, it may be stained with a solution of fluorescin, 1 part; sodium bicarbonate, 2 parts; distilled water, 200 parts; or with one of toluiclin-blue 1 to 1000.
CONJUNCTIVMS.—Keratitis must be distinguished from conjunctivitis. Le sions of the cornea are the most common and the most dreaded complications of conjunctival inflammation. But more especially on that account is it necessary to recognize promptly when the cornea bet,,nus imolled. The treatment gum d ktratitis is, too, in many re t, totallr different from that appro priatt to conjunctivitis. Ctiless the cor nea list.; f exhibits the characteristic opac ity or 1–ss ;:obstance, we cannot assume that it is affected. The redness of the perieorneal zone. while quite different
from the typical redness of conjunctivi tis, may be completely hidden by swell ing of the conjunctiva.
lizirts.—The diircrential diagnosis be tween keratitis and iritis is also very im portant. IIere, too, the detection of the actual lesions present in one or thc other of these structures is to be relied on. Corneal disease may cause apparent dis coloration of the iris; and in the early stage of keratitis the pupil is apt to be very small. But the use of a mydriatic (which would generally be very appropri ate for either disease) will, in keratitis, produce regular dilatation of the pupil, even if it is. not as wide as in the normal eye.
An error, much more grave, is to mis take inflammatory glaucoma for keratitis. Both diseases may present perieorneal redness, pain, photophobia, and haziness of the cornea; and glaucoma shows im pairment of the sense of touch in the cornea, as markedly as does neuropathic keratitis. In the latter disease the ten sion of the eyeball may be diminished; in glaucoma simulating keratitis it is always increased. The pupil in glaucoma is more or less dilated; in keratitis, un less a mydriatie has been used, it is con tracted or normal. The haziness of the cornea is more uniform and diffuse in glaucoma, while in keratitis it is more likely to be localized. Corneal ulcer may occur in glaucoma, but usually only in chronic cases. The chief pain of glaucoma is of an aching character, and is felt as much in the brow and cheek as in the eyeball. That of keratitis is more likely to be smarting or burning, or the sense of a foreign body. If a mydriatic has been used and the pupil has been dilated, the tension of the eyeball and the oplitlialinoscopic symptoms must be relied on. Haziness of the cornea, suffi cient to prevent an ophthalmoscopical diagnosis, is not likely- to occur in glau coma, except when the increase of ten sion is so great as to be quite unmistak able