Mayer speaks of these lesions in horses, but it is very difficult to diagnose them correctly, even with the aid of the ophthalmoscope. The very manifest bulging at the part may be due to excess of pigment, especially in the corpora nigra, and an exploratory puncture would only be warranted when the protrusion became excessive and injurious. One such puncture by Eversbusch led to infection and loss of the eye.
TUBERCULOSIS OF THE IRIS.
This has occurred as the result of inoculation of the aqueous humor in the smaller animals, and as a spontaneous localization of the disease in cattle (Hess, Röder, Fischöder, etc.). In Hess’s case, the left eye was shrunken to half the size of the sound right eye, and small caseated tubercles were present in both iris and choroid. There are usually coincident tubercles in other organs, and these with the nodular appearance of the iris swellings, if visible in life, may assist in diagnosis. (See Symptomatic Iritis, and Tuberculosis.)
CHOROIDITIS.
Causes: as in iritis: traumatic and infective. Exudative. Suppurative. Symptoms: as in iritis: less change in iris and of flocculi in the aqueous humor; opacity of lens and vitreous. Lack lustre choroid under ophthalmoscope, uneven, detached. Suppurative form: early profuse weeping, bleeding, later suppuration, pus oozing from orifice; panophthalmitis. Treatment: as in iritis; atropia; cocaine; astringents; purgatives; diuretics.
Causes. These are largely the same as those of iritis and cyclitis. Blows, traumas, foreign bodies, sand, cinders, dust, lime, fierce light, reflection from snow, water, etc., chills, draughts, storms, irritant gases, and a number of specific diseases like influenza, contagious pneumonia, canine distemper, rheumatism, omphalitis, pyæmia, etc., may be named. It is a common lesion of recurrent ophthalmia in horses, and is not unknown in tuberculous cattle. It is usually more or less involved in iritis, as the iris is in choroiditis. The name given to the disease which involves both, will depend mainly on whether the inflammation predominates in the iris or choroid. Mayer divides it into exudative and suppurative, the latter being a common result of trauma, and likely to issue in panophthalmitis.
Symptoms. These are largely those of iritis. The congestion and redness of the sclerotic around the margin of the cornea, the fact that the enlarged vessels are firm in the sclera and not easily moved as in conjunctival congestion, and a certain partial blindness, without much change in the brilliancy of the iris, or opacity or flocculi of the aqueous humor, would suggest choroiditis. Later some opacity of the lens, or its capsule or of the vitreous humor would be equally significant.
The only certain manifestations would be such as are found on ophthalmoscopic examination. Swelling and unevenness of the inner surface of the choroid, and a loss of luster, a change of its dark surface to light colored spots and patches, (dull-red, yellowish red, grayish green) and of the tapetum lucidum to a dirty grayish green in solipeds. Areas of minute blood clot may also be seen. But these are rarely recognized or indeed skillfully sought during life, and it is mainly to necropsies that we owe most of our diagnosis of choroiditis in the lower animals.
In the suppurative form there is early profuse lachrymation more or less tinged with blood, and later oozing of pus from between the lids. The redness and swelling of the conjunctiva and lids are very prominent features, and if the lids can be separated the corneal or scleral orifice may be seen oozing pus. If visible at all the anterior chamber shows yellowish opaque contents, and the symptoms of panophthalmitis supervene.
Treatment of the exudative form is essentially the same as for iritis. Atropia lotions with or without cocaine, also astringents, which may be used warm, and generally purgatives, diuretics, local bleeding, cupping, and counter-irritants are in order. In obstinate cases ointment of the yellow iodide of mercury, and in cases of extra tension puncture of the cornea may be the means of relief. Iridectomy may be advantageous under careful antiseptic precautions. In case of extensive or general suppuration (panophthalmitis) enucleation of the eye may be the only resort, and may contribute to save the other eyeball. (See Panophthalmitis).