259 



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 u]3per lid while the thumb depresses the lower one. In 

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

 farther than is possible by the above means, the upper lid may be 

 drawn dowTi by the ej^'elashes with the one hand and then everted over 

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

 against the middle of the lid. AVhere 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 

 transparency. The examination can be made much more satisfactory 

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

 a lamj) x^laced forward and outward from the eye which is to be exam- 

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

 be resolved by 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 crystalline 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 opacit}^, it will become diifused, cloudy, and indefinite. Thus, if 

 the large upright image becomes hazy and imjierfect over a particular 

 si)ot of the cornea, that will be found to be the seat of disease and 

 opacity. Should the large image remain clear, but the small upright 

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

 opacitj'- 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 ojjacity is in the substance of the lens itself or 

 in the posterior part of its capsule. 



If in a given case the pujiil remains so closely contracted that the 

 deeper parts of the eye can not be seen the ej'elids may be rubbed 

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

 found widelj" dilated. 



DISEASES OF THE EYELIDS. 



Congenital disorders. — Some faulty conditions of the eyelids are 

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



