Physiology. — ''PJiOtOLiraphy of the fundus of the human eye" .Y^y 

 Prof. I. K. A. Wertheim Salomonson. 



(Communicated in the meeting of April 27, 1917). 



Since the disco veiy of the ophthalmoscope b}' Helmholtz, dis- 

 closing the interior of the living human eye, many different attempts 

 have been made to keep a permanent record of the aspect of the 

 retina on a photographic plate. This proved to be much more difficult 

 than viewing the background of the eye. The greatest difficulty was 

 caused by the reflexes given off on the surface of the cornea and 

 the anterior and posterior surface of the lens. Different ways have 

 been tried to get rid of these reflexes and after more or less suc- 

 cessful attempts by Bagneris, Guilloz, Gerloff and others, Dimmer 

 succeeded in obtaining satisfactory results. Shortly afterwards Thorner 

 and also Wolff, working on different lines, showed photographs of 

 the living human retina w^hich were nearly as good as (hose of 

 DiMxMER. His photographs are generally excellent. 



Of the eyes of animals Nicolaew was also successful in obtaining 

 good negatives. But his method did not yield satisfactory results 

 with the human eye, the fundus of which is infinitely more difficult 

 to photograph than the animal fundus. 



For practical purposes as yet only Dimmer's and perhaps Wolff's 

 method have to be considered. But Dimmer's method necessitates a 

 costly instrumentarium, requiring much room and skilled assistance. 

 I do not know of its being used outside his own clinic, except by 

 a very few specialists (e. g. Hess.). 



The different methods for obtaining a reflexless image of the 

 fundus have been ably discussed by Gullstrand, who gave a clear 

 ,and critical review of the general and special conditions necessary 

 for getting clearly defined ophthalmoscopic images, free from any 

 reflex. Finally his results were embodied in his large demonstration- 

 ophthalmoscope, constructed by Zeiss, which shows the ophthalmos- 

 copic appearance of the human eye with less difficulty, more exten- 

 sively with a higher magnification and yet more clearly than any 

 other instrument of the same kind. As yet this instrument cannot 

 be used for photographic purposes. But it seemed to me that it 



