CATARACT. 



367 



should be an unfavorable one. Hereditary cataract shows little 

 inclination to enlarMment, as is also the case in senile cataract. 

 In soft cortical cataracts we may see a rapid opacity of the lens in 

 a few days or weeks. The sight is entirely lost and medical treat- 

 ment is of little use. 



Therapeutic Treatment. A cataract may be removed by 

 an operation, and this is much more advisable in the dog because 

 it is, as a rule, attended without any great danger, and its results 

 are generally beneficial, producing a partial restoration of the vision. 

 It is advisable to perform the operation of cataract after having 

 first dilated the pupil by means of atropia, and then performing the 

 operation under ether. The author has tried cocaine alone, but 

 lie finds it unsatisfactory. The animal must be tied up, placed 

 on a table, and ether or chloroform administered. The operation 

 is performed by one of the following methods : 



Opening of the Capsule. The anterior capsule of the lens 

 has to be opened in a transverse way with what is known as a dis- 

 cission needle. (Fig. 80, a.) The fluid 

 in the anterior chamber causes a gradual 

 breaking up and reabsorption of the lens. 

 An assistant holds the eyelids open and 

 the operator seizes a fold of the conjunc- 

 tiva with a small tenaculum, holding the 

 eye firmly with the left hand, while hold- 

 ing the needle in the right hand placed 

 on the animal's head to steady it. The 

 needle is then introduced into the cornea, 

 in the middle of the lower external quad- 

 rant, in such a direction as to meet the 

 ciliary insertion of the iris and as far as 

 the upper internal quadrant. Before the 

 point of the needle has reached this latter 

 point, however, it is placed firmly on the 

 capsule of the lens, and this is cut 

 through in a transverse direction with a 

 lever like movement of the needle (Fig. 



81). The instrument must then be removed in the same way that 

 it was introduced in perforating the cornea. After the operation 

 the animal must be placed for some time in a dark place and 



a, stop discission needle ; 6, 

 Gr^efe's cataract knife; c, 

 Daviel's cataract spoon. 



