EFFECTS OF RADIANT ENERGY ON THE EYE. 665 



vesicle involving two-thirds the area of the cornea. This condition 

 remains almost unchanged until about the thirteenth day, except that 

 on al)out the sixth day vascularization of the cornea is observed. 

 On about the fourteenth day the inflammatory reaction, which has 

 almost completely subsided, begins again. This is probably a reaction 

 of repair. During this time the process of vascularization makes 

 rapid progress and the new vessels invade the central area which is 

 now somewhat firmer, but still pits when touched by a probe. On the 

 twenty-fifth day the inflammatorv' reaction is again almost gone and 

 the new ^•essels have begun to disappear. The exposed area is now 

 only slightly swollen and no longer pits, but is very cloudy. On the 

 thirty-third day the vessels have largely disappeared. The exposed 

 area is no longer swollen and presents a translucent appearance. 

 After two months the surface of the cornea is smooth and there is a 

 translucent interstitial opacity. The repair of the injury is much more 

 complete than could be expected in the case of a human cornea. 



After an exposure of five minutes i. e. one-fourth the former dosage, 

 to the magnetite arc through the quartz lens system and water cell 

 the cornea undergoes softening in the exposed area as in the case 

 of the longer exposures. The injury, however, is repaired without 

 vascularization of the cornea, leaving a central translucent scar. 



The Histological Changes Produced in the Cornea by Abiotic 



Radiations. 



The histological changes produced in the cornea by abiotic radia- 

 tions were studied chiefly in eyes exposed to the magnetite arc with 

 and without interposition of quartz lenses and various screens. Corre- 

 sponding to the differences in the clinical effects, different histological 

 effects were obtained when a crown glass screen was used than when 

 it was omitted. The chief difference was that with the crown screen 

 the corneal stroma escaped injury, due to the fact that it was then 

 protected from all waves which it strongly absorbed, namely, waves 

 less than 295 fjifx in length. With the crown screen, exposures sufficient 

 to destroy the epithelium always severely injured the corneal cor- 

 puscles. Without the crown screen, on the other hand, owing to the 

 greater abiotic activity of the short rays stopped at the surface of the 

 cornea, the epithelium was destroyed by exposures too short to have 

 any visible effect on the corneal corpuscles. On account of these 

 differences the histological effects produced by the short waves and 

 relatively long waves will be described separately. 



