786 WALKEK. 



cases numerous previous observers ^^*, Vinsonneau, Stocke, Pergens 

 V. Pflugk, Arlt, Lesearret, Menacho, Villard, found similar changes. 

 Lamhofer in 1912 found a chorioretinal exudate with pigmentation 

 and at the same time Best reported a case with decreased peripheral 

 field and adaptation. Erythropsia has also been noted by Birch- 

 Hirschfeld and by Braunschweig. 



In 26 out of 36 cases of sun blinding in the eclipse of 1912, Jess ^°° 

 working in Hess's clinic found a ring-scotoma 20° to 40° from the 

 fixation point. In this ring formed area, white appeared gray, and 

 colors were not seen in a few cases, in others red was called yellowish, 

 green was called gray, and blue was called yellow. In the course of a 

 week the damage gradually decreased until only a small semicircular 

 area of scotoma was left below. Hess ^^* states that this finding has 

 been verified by Peppmueller, Pergens, and Hoppe. Speleer found 

 enlargement of the blind-spot ring-scotoma and concentric contraction 

 of the field after sun blinding. Birsch-Hirschfeld*^, however, has 

 taken exception to the ring-scotoma of Jess, finding that it was a 

 normal phenomenon and not specially related to eclipse-blindness. 



The large number of functional impairments due to lightning and 

 short-circuit flashes cannot be referred definitely to any given range 

 of wave lengths. These derangements have been reported in great 

 numbers and variations. There may be permanent blindness or 

 temporary blindness in one or both eyes. Central and peripheral 

 scotomata are more common and while usually temporary they may 

 be permanent. Hancock ^^^ in 1907 reported a case of ring-scotoma. 

 Disturbances of color vision are very common but temporary. These 

 include erythropsia, red blindness, red green and blue green blindness 

 and scotomata. Ophthalmoscopic examination may show nothing 

 even in severe cases or there mav be punctate spots in the macula as 

 in sun blinding, Uhthoff "5, Haab ", Terrien ^^s. Birch-Hirschfeld ^i 

 considers rays from 350 fx^ to 400 nfj. most active in producing these 

 disturbances with probably even more assistance from blue and violet 

 rays because of the greater intensity. 



While usually there is outer eye trouble in these cases a few have 

 reported functional disturbances without photophthalmia. Nelson 

 Dering^^* Le Roux and Renaud ^^5 Maclean ^^^ and Purtscher^^^ 



In snow blinding functional disturbances have been noted to take 

 the form of temporary amblyopia (Widmark *^^ citing Enald) night- 

 blindness (Widmark*^^) and day lilindness. In 1907 Best & Haenel ^^ 

 found after snowblinding a central scotoma for red and green extend- 

 ing about 10° from the fixation point. This disturbance disappeared 

 in the course of six weeks. 



