778 WALKER. 



Injuries to the Lens. 



Czerny ^^ in 1867 in his blinding experiments with sun's rays noted 

 turbidity in the lens cortex but no change in the lens capsule. Deutsch- 

 man ^^ repeating these experiments in 1882 got the same results. 

 Herzog^^^ in 1903 obtained similar results with the carbon arc, glass 

 lenses and heat filters. These lens changes were undoubtedly due 

 to the thermic action of visible rays. 



Widmark*^'' in his experiments on the outer eye, 1889-1892, with 

 the 1200 c. p. arc light noted lens changes microscopically. These 

 he did not find when ultra violet rays were screened out by a quinine 

 sulphate solution therefore he concluded they were the etiological 

 factor. Ogneff ^^^ in 1896 repeated this experiment with a 6000 to 

 8000 c. p. arc lamp at a distance of 50 cm. to 1 meter for 15 to 20 min. 

 but found no lens trouble though all the conjunctival corneal and iris 

 troubles were present. 



Widmark^^^ repeated his work again in 1901 using a 4000 c. p. zinc 

 arc in much the same way with the same results. Two rabbits A & B 

 were exposed to the same arc light at the same time. In the case A 

 the light traversed two glass lenses separated by 5 to 6 cm. of a 10% 

 quinine sulphate solution. The distance from arc to lenses was 13.6 

 cm. and light was concentrated on the dilated rabbit's eye 6 cm. 

 beyond the lenses. Ultra violet rays and heat rays were cut out by 

 this method and no lens changes were found. In case B the conditions 

 were the same except that the lenses were of quartz, separated by 

 water. In this case in addition to the usual disturbance in the outer 

 eye and iris, the lens capsule in the pupillary area showed at first 

 intense staining of the nuclei, mitosis, cell proliferation and destruc- 

 tion. There was swelling of lens fibre bundles with partial destruction. 

 Also transudate between the cortex and capsule. 



In 1904 with a 3| to 4| amp. Finsen light, Birch-Hirschfeld ^^ 

 could not get lens changes after 5 to 10 min. exposures. Hertel ^^^ in 

 26 rabbits used in the previously mentioned experiment, and also 

 Strebel ^^^ failed to get lens changes, though the usual outer eye and 

 iris changes were produced as previously observed. 



Hess ^^* in 1907 used a 3| amp. uviol mercury vapor lamp with a 

 65 cm. tube. He exposed 1 to 16 hours at a distance of 10 to 30 cm. 

 The animals used were rabbits, guinea-pigs and frogs. He found 

 outspoken lens changes as described by ^Yidmark. These lens changes 

 appeared about 48 hours after a 6 to 12 hour exposure. Surrounding 



