EFFECTS OF RADIANT ENERGY ON THE EYE. 667 



forty-eight hours. The purulent infiltration is greater the nearer 

 the exposed area lies to the limbus, but is never sufficient to account 

 for more than a small part of the haziness of the cornea. It is also 

 greater the larger the area affected by the exposure. 



The corneal endothelium in the most exposed region is entirely 

 cast off within twenty-four to forty-eight hours. At the margins of 

 the defect the nuclei show pycknosis and the cytoplasm often con- 

 tains the characteristic basophilic and eosinophilic granules. These 

 changes are also found after somewhat less intense exposures, in cells 

 that remain adherent in exposed regions. 



Repair of the Corneal Injury. Five days after exposure the epithe- 

 lium is usually found reformed but thin. The visible corneal corpus- 

 cles are still further reduced in number, and of those visible many still 

 contain eosinophilic and basophilic granules. Towards the periphery 

 the nuclei are abnormally rich in chromatin and many of them en- 

 larged. Some of them show direct division and budding. Occa- 

 sionally a mitotic figure is seen here. The endothelium has not 

 reformed. In places on Descemet's membrane there are eosinophilic 

 and basophilic granules evidently left by necrotic endothelial cells. 



After ten days the epithelium is still thin. The number of corneal 

 corpuscles in the exposed area has slightly increased. The basophilic 

 granules are apparently unchanged, but the eosinophilic granules in 

 some cells stain less deeply and in others have apparently become 

 confluent causing the whole cytoplasm to stain reddish. The nuclei 

 are rich in chromatin, often polymorphous in shape, and sometimes 

 show direct division and !)udding. Few if any mitotic figures are 

 seen. The endothelium is completely reformed. After five weeks 

 the cornea presents an almost normal appearance. The corneal 

 corpuscles now slightly exceed the normal number. Many of the 

 nuclei are abnormally large and a few cells contain double nuclei. 

 The cause of the slight corneal opacity seen at this stage during life 

 is not evident from the microscopic examination. 



Histological Changes produced in the Cornea by Light rich 

 IN Abiotic Waves less than 295 n/j. in Length. 



With the bare magnetite arc, to destroy the epithelium of the cor- 

 nea requires an exposure only one-eighteenth of that required when 

 a crown screen (295 iifx) is used. In the former case it is evident 



