552 DISEASES OF THE GLOBE AND ORBIT 



Prognosis. Depends upon the cause. 

 Treatment. Determine the cause and eliminate it by 

 proper treatment. 



STRABISMUS. 



Definition. A deviation of one of the eyes from its normal 

 direction so that the visual axes cannot be focussed simul- 

 taneously on the same objective point. 



Etiology. It may be due to a mechanical interference 

 with the movement and position of the eyeball, paralysis of 

 the muscles of the eye, intracranial paralysis, spasms of the 

 eye muscles, cerebral hemorrhage, and poisoning. 



Diagnosis. The diagnosis is not difficult. One eye will 

 be turned inward or outward while the fellow one is directed 

 straight ahead. 



Treatment. A palliative treatment consists in applying 

 a counterirritant to the region of the orbit and administering 

 internally small doses of iodid of potash. A radical treat- 

 ment is to perform a tenotomy, severing one of the tendons 

 of the eye muscle at its insertion into the sclera. The 

 particular tendon to be divided is determined by the indi- 

 vidual case. If the strabismus is convergent the internal 

 rectus is cut; if divergent, the external. The operation is 

 briefly as follows: Give a general anesthetic. Flush the 

 eye with antiseptics and follow by a solution of codrenin to 

 control the hemorrhage. Cut through the conjunctiva and 

 carefully dissect down to the tendon which grasp with a 

 blunt hook, pull forward and cut oft' with a scissors. Unless 

 the tendon is entirely severed the results will not be satis- 

 factory. The wound in the conjunctiva may be left open. 

 Flush out daily with antiseptic solution. 



NYSTAGMUS. 



Definition. A continuous rolling movement of the eye- 

 ball. It occurs occasionally in dogs. It very often accom- 

 panies epilepsy, convulsions, parasitic invasion of the ear, 

 catarrh of the ear and sometimes accompanies chloroform 

 narcosis. 



