VISION. 



(3) Cycloplegics (paralysants of the ciliary muscles), such as 

 atropine, homatropine, scopolamine, etc. 



(4) Anaesthetics (local), such as cocaine, eucaine, holocaine. 

 Of the mydriatics, the first four are in most common use. They 



differ from one another in intensity and duration of effect, in the 

 order named. The mydriatics, as a rule, increase the intraocular 

 tension. 



Exercise. Instil a drop of homatropine into a subject's eye. 

 What effect does it have on the pupil ? Upon accommodation ? 

 Explain the action. 



Instil a drop of eserine in the same eye. What effect is pro- 

 duced ? 



Instil a drop of cocaine into another subject's eye. Brush the 

 cornea, lightly, with a wisp of cotton. Note the anaesthesia and 

 the effect on the pupil. Which produces the more complete 

 mydriasis, cocaine or homatropine? 



[195] 



