THE PRESENT STATUS OF LIGHT THERAPY ^ 



SCIENTrFIC AND PRACTICAL ASPECTS 



By Edgab Mayek, M. D. 

 Saranac Lake, N. Y. 



[With 1 plate] 



Although there is much information concerning results of irra- 

 diating man and animals, explanations and indisputable generaliza- 

 tions are sadly lacking. Wlien it is realized that even in photochem- 

 ical reactions the physical process is not completely understood, the 

 difficulty of explanation in biology and clinical medicine becomes 

 more evident. No single explanatory hypothesis for the results 

 ascribed to light action can yet be formulated, as there is great neea 

 of data obtained under definitely controlled conditions of dosage, 

 intensity, and wave lengths in normal and in abnormal organisms. 



There is a lack of agreement between the practical and thera- 

 peutic results and the scientific and experimental observations. Ex- 

 periments have been carried out for the most part on healthy men 

 and animals, whereas usually the practical results have been ob- 

 tained on the sick. The abnormal organism is much more sensitive. 

 Diseased tissue may vary from normal in sensitiveness to radiation. 

 The animal skin is not perhaps comparable to the same organ in 

 man (as, for example, in exposing shaved guinea pigs to sunlight, 

 it is most difficult to produce erythema). In many reports the im- 

 portance of sky radiation has been ignored, whereas it is possible 

 that the beneficial effects of sunlight are in a great measure due to 

 its luminous and infra-red portions.^ It has been shown at Davos 

 (Switzerland) that the radiation from the whole sky in summer has 

 almost four times more ultra-violet shorter than the wave lenoth 

 366 millimicrons than direct sunlight,^ and at Mount Wilson sky 

 light was found to be several times richer in violet and ultra-violet 

 than was direct sunlight.^ Hence, although the intrinsic brightness 



1 Reprinted by permission from The Journal of tbe American Medical Association, vol. 

 98, pp. 221-230, Jan. 16, 1932. 



^ Dorno, Carl, Studien (iber Luft und Licht im Hochgebirge, Brunswick, 1911. 



3 Dorno, Carl, Physik der Sonnen- und Himmelstrahlung, Strahlentherapie, 1919. 



* Pettit, Edison, The Comparative Physical Properties of Sunlight and Light from 

 Artlfleial Sources, Trans. 24th annual meeting. National Tuberculosis Association. 



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