EFFECTS OF RADIANT ENERGY ON THE EYE. 635 



examined the effect of the other radiations which are received from 

 natural or artificial sources. 



Our first aim Avas to ascertain what quantitative relations existed 

 between the incidence of energy on the eye and the pathological effects 

 which might follow. Especially we desired to ascertain whether 

 these effects were proportional to the incident energy and hence to 

 such primary lesions as might be produced by it, or serve to set in 

 train pathological changes of an extent not proportionate to the 

 primary inducing cause. To this end we first turned our attention 

 to the so-called ophthalmia electrica or photophthalmia (Parsons), 

 at once the earliest known and commonest of the superficial pathologi- 

 cal effects of radiation. Probably first observed by Foucault and 

 Despretz about sixty years ago, it received its first notice from the medi- 

 cal standpoint in a paper by Dr. Charcot. ^^ His brief clinical observa- 

 tions are here reproduced in full as they are typical so far as the 

 external effects go of a mild case of this particular affection. The 

 luminous effects as described, are not characteristic and were no 

 doubt purely psychical, and due perhaps to undue attention having 

 been called to the sensations of light normally arising in the dark 

 adapted eye. The fusion and vitrification of refractory substances 

 produce far more intense eft'ects of this kind than would have been 

 noted in the other experiments cited by Dr. Charcot. 



Erythema Produced by the Action of the Electric Light. By Dr. 

 Charcot. — The fourteenth of February last two chemists were cooperating in 

 making some experiments on the fusion and vitrification of certain substances 

 by the action of the electric battery. They made use of a Bunsen battery of 

 120 elements. The experiments lasted about an hour and a half; but during 

 this time the action of the battery was frequently interrupted and it was not 

 working in all more than twenty minutes. At the distance of the experi- 

 menters from the arc, about fifty cm., they were not sensible of a rise in tem- 

 perature. Nevertheless, that evening and during the whole night which they 

 passed without sleep they found in their eyes a feeling of severe irritation and 

 saw almost continually flashes and colored spots. The next day both had 

 upon their faces erythema of a purplish color with a feeling of pain and tension. 

 In the case of M. W., the right side of whose face alone was exposed to the 

 luminous arc, the reddening covered that whole side from the roots of the hair 

 to the chin, and the sparks were only seen as if before his right eye. In the 

 case of M. M. who had held his head lower and whose face had been protected 

 against the arc by his brow, the brow only was affected with erythema. Upon 

 both the experimenters the appearance of the skin in the parts affected was 

 exactly that of sunburn; a slight desquamation was established at the end of 

 four days and lasted in all five or six days. 



