VISION. 251 



holds alter the size of the image ? Account for 

 observation. 



b. Observation of the hyperopic eye. 

 Adjust the model for 3 D. of hyperopia. 



(4) Does an increase of the distance of the lens from 

 the cornea cause the image of the papilla to be 

 altered in size? Account for all phenomena. 



c. Observation of the myopic eye. 



Adjust the model to represent 3 D. of myopia. 



(5) Does the increase of the distance of the lens from 

 the eye cause the image of the papilla to become 

 altered in size or reversed in position ? Account for 

 all phenomena. 



(6) If the position of the + 12 D. lens which the ob- 

 server holds remain the same 8 cm. from cornea 

 will there be any variation in the distance from the 

 cornea of the retinal image for the hyperopic eye 

 and myopic eye ? 



Will the distance for the hyperopic eye be 

 greater or less than for the emmetropic eye ? Why ? 

 Will the distance for the myopic eye be greater or 

 less than for the emmetropic eye ? Why ? 



d. Observation of the human eye. 



At this point in the student's work, let him practice 

 the direct and indirect method of ophthalmoscopy 

 upon his comrades, after two or three days of practice 

 he may pass to the following exercise. 



