DISEASES OF THE nOKSE. 255 



may be kept within bounds, and oftentimes even the interior of the 

 eye can be seen. As a rule it is best to use the right hand for the 

 left eye, and the left hand for the right, the finger in each case being 

 pressed on the upper lid while the thumb depresses the loAver one. In 

 cases in which it is desirable to examine the inner side of the eyelid 

 farther than is possil)le b}^ the above means, the upper lid may lie 

 drawn down by the e3^elashes with the one hand and then everted ov(>r 

 the tip of the forefinger of the other hand, or over a probe laid flat 

 against the middle of the lid. Where the interior of the eye must be 

 examined it is useless to make the attempt in the open sunshine or 

 under a clear sky. The worst cases, it is true, can be seen under such 

 circumstances, but for the slighter forms the horse should be taken 

 indoors, where all light from above will be shut off, and should be 

 placed so that the light shall fall on the eye from the front and side. 

 Then the observer, placing himself in front of the animal, will receive 

 the reflected rays from the cornea, the front of the lens and the back, 

 and can much more easily detect any cloudiness, opacity or lack of 

 transparenc3^ The examination can be made much more satisfactory 

 by placing the horse in a dark chamber and illuminating the eye by 

 a lamp placed forward and outward from the e3"e which is to be exam- 

 ined. Any cloudiness is thus easily detected, and any doubt may 

 be resolved b}'' moving the lamp so that the image of the flame may be 

 passed in succession over the whole surface of the transparent cornea 

 and of the cr3"stalline lens. Three images of the flame will be seen, 

 the larger one upright, reflected from the anterior surface of the eye; 

 a smaller one upright, reflected from the anterior surface of the lens; 

 and a second small one inverted from the back surface of the lens. 



So long as these images are reflected from healthy surfaces they will 

 be clear and perfect in outline, but, as soon as one strikes on an area 

 of opacit3", it will become diffused, cloudy, and indefinite. Thus, if 

 the large upright image becomes haz3^ and imperfect over a particular 

 spot of the cornea, that will be found to be the seat of disease and 

 opacit3^ Should the large image remain clear, but the small upright 

 one become diffuse and indefinite over a given point, it indicates 

 opacity on the front of the capsule of the lens. If both upright 

 images remain clear while the inverted one becomes indistinct at a 

 given point, then the opacity is in the substance of the lens itself or in 

 the posterior part of its capsule. 



If in a given case the pupil remains so closeh^ contracted that the 

 deeper parts of the eye can not be seen, the e3"elids ma3^ be rubbed with 

 extract of belladonna, and in a short time the pupil will be found 

 widel3^ dilated. 



DISEASES OF THE EYELIDS. 



Congenital disorders. — Some fault3'^ conditions of the e3'elids are 

 congenital, as division of an eyelid in two, after the manner of harelip. 



