EFFECTS OF RADIANT ENERGY ON THE EYE. 699 



conversion took place chiefly in the pigment epithelium and inner 

 layers of the chorioid, and that the outer layers of the retina proper 

 were affected b\^ the heat conducted therefrom. 



An interesting problem is the exact determination, under various 

 conditions, of the minimum intensity and duration of exposure to 

 visible and infra red rays necessary to produce heat effects on the ret- 

 ina. A discussion of this problem will be found on pages 721 and 732. 



The experiments in which heat effects on the retina were obtained 

 by means of the magnetite arc were Experiments 53, 55, 57 58, 59, 

 88, 89. 



Following are the experiments with sunlight concentrated by the 

 large mirror. 



Experiments. 



SunligJit Focusscd on Cornea by Large Mirror. 



Experiment 95. Without water cell or screen. Pigmented eye. 

 Three exposures, j second, | second, and 10 seconds respectively. 

 No inflammatory reaction. Enucleation at end of 33 days. Lens 

 epithelium normal. Three burned areas in fundus of different grades 

 of severity. 



Experiment 96. Water cell. Flint glass screen (335 ^t^t). Albino. 

 Exposed 4 seconds. No inflammatory reaction. Lid reflex to light 

 abolished. Enucleation at end of 48 hours. Two contiguous bin-ned 

 areas in fundus, one exactly on disc. Marked hemorrhagic retinitis. 

 Slight hemorrhage from retina into vitreous. 



Experiment 97. Blue uviol screen. No water cell. Pigmented 

 eye. Exposed 1 minute. After 1 hour: Pupil contracted to | normal 

 size, does not react to light. After 24 hours: Lid margins inflamed, 

 lower one ulcerated, no lid reflex to light. Cornea clear. After 3 

 days : Cornea shows purulent infiltrate below (infected from ulcerated 

 lid). Enucleation. Fundus shows two contiguous burned areas, 

 one at margin of disc. Microscopic examination: (3 days): Slight 

 purulent infiltration of cornea. Hyaline necrosis of iris. Lens epi- 

 thelium normal in pupillary area, shows proliferative changes beneath 

 pupillary margin (heat effect due to contact with heated iris. See 

 page 696). 



Experiment 98 (PI. 4, Fig. 14). Water cell. No screen. 

 Albino. Exposed 14 seconds (misty day). No inflammatory reac- 



