DISEASES OF THE EYE. 267 



no effort to evade it. Sometimes the edges of the contracted pupil 

 become adherent to each other by an intervening plastic exudation, 

 and the opening becomes virtually abolished. In severe inflamma- 

 tions pus may form in the choroid or iris, and escaping into the 

 cavity of the aqueous humor show as a yellowish white stratum 

 below. In nearly all cases there is resulting exudation into the lens 

 or its capsule, constituting a cloudiness or opacity (cataract), which 

 in severe and old-standing cases appears as a white fleecy mass behind 

 a widely dilated pupil. In the slighter cases cataract is to be recog- 

 nized by examination of the eye in a dark chamber, with an oblique 

 side light, as described in the introduction to this article. Cataracts 

 that appear as a simple haze or indefinite fleecy cloud are usually on 

 the capsule (capsular) , while tlfose that show a radiating arrangement 

 are in the lens (lenticular), the radiating fibers of which the exudate 

 follows. Black cataracts are formed by the adhesion of the pigment 

 on the back of the iris to the front of the lens, and by the subsequent 

 tearing loose of the iris, leaving a portion of its pigment adherent 

 to the capsule of the lens. If the pupil is so contracted that it is 

 impossible to see the lens, it may be dilated by applying to the front 

 of the eye with a feather some drops of a solution of 4 graiiis of 

 atropia in an ounce of water. 



Treatment. — ^The treatment of internal ophthalmia should embrace, 

 first, the removal of all existing causes or sources of aggravation of 

 the disease, which need not be here repeated. Special care to protect 

 the patient against cold, wet, strong light, and active exertion must, 

 however, be insisted on. A dark stall and a cloth hung over the eye 

 are important, while cleanliness, warmth, dryness, and rest are 

 equally demanded. If the patient is strong and vigorous, a dose of 

 4 drams of Barbados aloes may be given, and, if there is any reason 

 to suspect a rheumatic origin, one-half a dram powdered colchicum 

 and one-half ounce salicylate of soda may be given daily. Locally, 

 the astringent lotions advised for external ophthalmia may be resorted 

 to, especially when the superficial inflammation is well marked. More 

 important, however, is to instill into the eye, a few drops at a time, a 

 solution of 4. grains of atropia in 1 ounce of distilled water. This may 

 be effected with the aid of a soft feather, and may be repeated at inter- 

 vals of ten minutes until the pupil is widely dilated. As the horse 

 is to be kept in a dark stall, the consequent admission of light will be 

 harmless, and the dilation of the pupil prevents adhesion between the 

 iris and lens, relieves the constant tension of the eye in the effort to 

 adapt the pupil to the light, and solicits the contraction of the blood 

 vessels of the eye and the lessening of congestion, exudation, and in- 

 traocular pressure. Should atropia not agree with the case, it may be 

 replaced by morphia (same strength) or cocaine in 4 per cent solution. 

 Another local measure is a blister, which can usually be applied to 



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