372 DISEASES OF THE EYES. 



although it is difficult to detect blindness in one eye. The veter- 

 inarian may recognize blindness by the unaltered condition of the 

 pupil when in contact with or close to light. It is necessary to 

 cover up one eye of the animal in order to test the other, as the 

 influence of light may act in a reflex way from the healthy organ. 



We must especially point out that in very rare cases we may see 

 a certain amount of reaction in the pupil under the influence of 

 light, notwithstanding the fact that complete blindness exists. 

 The author has observed this in a dog which had become blind 

 from nervous distemper. Later symptoms, however, are not 

 known; the author was unable to make any further observations. 

 The brain of the animal had, however, probably undergone cer- 

 tain alterations in its hemispheres, although the patient did not 

 seem to be affected with any cerebral complications. This is one 

 of the so-called cases of " spiritual blindness." 



Moller and Eversbusoh have recognized pathological alterations 

 in the visual nerve and retina in the form of small red spots and 

 opacity of the retina (symptoms of retinitis), also a lifting or 

 enlargement of the papilla. The author had two cases in which 

 he observed papillo-retinitis from its beginning till it entirely dis- 

 appeared. All these processes may be recognized by means of the 

 ophthalmoscope. 



For therapeutic treatment of inflammation of the eye, which is 

 not given in this chapter, we refer you to the text-books on oph- 

 thalmology. It consists, as a rule, in rest, keeping the animal in 

 the dark, the use of atropine or eserine, and an occasional laxative. 



Prolapse of the Eyeball. 

 {Exophthalmus ; Prolapsus Bulbi Oculi.) 



There are a number of causes that produce prolapse of the eye- 

 ball; it may be crowded out of the cavity of the eye, or exposed 

 in its external circumference by the swollen and distended eyelids 

 which are closely adherent to its posterior surface. This condi- 

 tion occurs especially in bulldogs, although it may occur in anv 

 breed. The dog does not possess any bony arch of the eye 

 (zygomaticus), the space being filled up by a ligament, and the 

 muscles are also very weak. Occasionally, from any mechanical 

 force, such as blows in the region of the eye, or bites in its 



