SYSTEMATIC REVIEW OF THE LITERATURE RELATING 



TO THE EFFECTS OF RADIANT ENERGY 



UPON THE EYE. 



By C. B. Walker, A.M., M.D. 



Chronological Account. 



Historically we find the first study of the properties of the ultra 

 violet light in connection with the eye was commenced long before 

 high power lamps were invented or the role of ultra violet rays in 

 producing eye-injuries was established. The first work, was stimu- 

 lated by purely scientific interest with no prophylaxis or therapy in 

 view; in fact these latter factors did not enter for several decades. 



As early as 1845, Brucke ^^ laid the foundations for subsequent work, 

 in his investigation of the reason for the invisibility of the ultra violet 

 rays. In order to determine whether these rays failed to traverse 

 the eye media or failed to stimulate the retina, he first studied the 

 absorptive power of the eye media. He found that Gum Guaiacum 

 had a characteristic bluish appearance in ultra violet light. By 

 means of this substance he was able to say that the lens absorbed 

 ultra violet rays strongly and the cornea and the vitreous humor to a 

 less extent. Later with the assistance of Karstein he found with 

 sensitive paper that a combination of lens, vitreous humor and 

 cornea, diminished somewhat the intensity of the violet, began to 

 absorb more just outside the visible spectrum, was especially strong 

 on the "M" {372 n/j) line of the Draper spectrum, and practically 

 total beyond, that is for rays less than 370 ^t/x. 



In 1852 Stokes ^^^ discovered fluorescence and thus afforded another 

 means of studying the absorption of the eye media. Donders^^ with 

 Rees in 1853 threw a solar spectrum upon a screen covered with qui- 

 nine sulphate which by its fluorescence rendered the ultra violet rays 

 visible. Various eye media, unfortunately enclosed in glass con- 

 tainers, were then interposed in the path of the ultra violet rays. The 

 absorption power of glass itself rendered these results of little value. 



In 1855 Helmholtz ^^^ studied the lower limit of the visible spectrum 

 using a quartz prism, but his high-grade myopia interfered. He also 

 used the fluorescing screen of quinine sulphate and studied the fluo- 



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