VISION. 253 



direction of the mirror rotation and that it is rela- 

 tively quick. 



(II) Adjust the model to represent a myopia of more 

 than 1 D. 



(4) Note that the shadow movement is opposite the 

 direction of the mirror rotation and that it is quick 

 when the myopia is of low degree, slow when of 

 high degree. 



(5) Observe alternately the three conditions indi- 

 cated above until their differences are so familiar 

 that any one of the conditions may be readily and 

 unerringly detected by the observer when they are 

 arranged for him by the instructor. 



c. Observation of the hyperopic eye. 



Adjust the model to represent any degree of hyper- 

 opia. 



(6) Note that for a low degree of hyperopia the 

 shadow movement is with the mirror rotation and 

 quick. 



(7) Note that for higher degrees of the condition the 

 shadow movement is with the mirror and slow. 



(8) How may one differentiate a high degree of 

 myopia from a high degree of hyperopia ? 



(9) Is there any difference in the size, shape, dis- 

 tance or position of the shadows in these two condi- 

 tions ? 



d. Observation of the human eye. 



Let the student practice upon his comrades. 



NOTE : Observation of the astigmatic eye is inten- 

 tionally omitted here. It belongs more espcially to the 

 clinical phase of the subject. 



