EFFECTS OF RADIANT ENERGY ON THE EYE. 721 



Germany produced a total of many hundred cases of more or less in- 

 jury to the eyes, as noted by Wendenberg ^^°. Every eye clinic re- 

 ceived its toll of more or less severe cases. Clinically the immediate 

 eflFect is marked and immediate scotoma, which does not pass away 

 promptly but leaves more or less seriovis cloudiness of vision and 

 accompanying loss of acuity which may be temporary, lasting a few 

 weeks, or in severe cases permanent. The scotoma is commonly 

 central and generally of small extent, in a marked proportion of the 

 cases corresponding fairly well with the dimensions of the sun's image, 

 although wide variations from this may be due to repeated fixations 

 overlapping or reenforcing each other. As it is generally impossible 

 to tell just how long or how often the patient fixed the phenomenon 

 nothing definite can be postulated concerning various varieties of 

 scotoma which have been noted by various observers. The ophthal- 

 moscopic observations usually show changes ranging from scarcely 

 perceptible, to conspicuous and permanent pathological appearances 

 involving lasting and destructive injury to the retina. Metamorphop- 

 sia sometimes appears, the significance of which will be apparent in 

 connection with some of our experiments, and diminution of visual 

 acuity is fairly well marked, often falling below one third. With the 

 progress of time the scotoma tends to contract and in mild cases 

 normal vision is regained within some weeks, or in the most severe 

 cases great reduction in acuity persists permanently.* 



Our experiments have been directed to the production of an artificial 

 eclipse blindness in animals, and the examination of the lesions pro- 

 duced, following up the work of Czerny ^^, Deutschman ^^, Herzog ^^^, 

 and others with special reference to the intensity required to produce 

 the lesions noted. The character of the lesions produced in these 

 experiments is described elsewhere (page 697). The apparatus em- 

 ployed was powerful enough to produce prompt and acute effects. 

 For most of the experiment we employed the mirror apparatus shown 

 in Plate 8 which consisted of a silvered glass mirror 26 cm. in diameter 

 and 1.5 meters focal length, carried, as shown, in a fork mounting set 

 up approximately in the meridian and fitted with slow motions in 

 right ascension and declination so that the beam could be readily 



* Jess 200 describes relative ring scotoma for colors in a series of cases, but 

 does not offer a convincing explanation for its occurrence. Boehm4:8 was un- 

 able to demonstrate it in any of his cases, although he examined them with 

 special reference to it. Birch-Hirschfeld^l suggests that a normal eye would 

 show the same condition if examined in the same way. This criticism would 

 seem to apply with equal force to the similar scotomata reported by Birch- 

 Hirschfeld35 himself as occurring after exposure to ultra violet light. 



