68G VERHOEFF AND BELL. 



POSSIBLE EFFECTS OF ABIOTIC RADIATIONS ON THE 

 RETINAE OF APHAKIC EYES. 



Since it has been shown experimentally that abiotic waves may pass 

 through the cornea and injure the lens epithelium, it would seem that 

 exposure of an aphakic eye to a light source rich in such waves might 

 seriously damage the retina. Assuming as is probable, that the retina 

 has the same susceptibility to abiotic action of light as the lens epi- 

 thelium, the minimal exposure to the bare magnetite arc necessary to 

 injure the retina of an aphakic human eye may be closely approxi- 

 mated from the data of our experiments. The working diameter of 

 the single quartz lens was 4.2 cm., and the w^orking focal distance 14 

 cm., making the working aperture 1/3.3 This corresponds to the aper- 

 ture of a human aphakic eye with a pupil 4.5 mm. wide. Now we 

 found that the lens epithelium of a normal rabbit's eye was unaffected 

 by an exposiu-e of 6 minutes to the single lens system through a crown 

 screen (29.5 ^i^), but moderately affected by an exposure of 12 minutes. 

 The liminal exposure may therefore be taken as 8 minutes. The total 

 loss by reflection etc. from the surfaces of the lenses, screen, and water 

 cell, amounts to about 50%. Deducting this percentage, the mini- 

 mum exposure to the magnetite arc necessary to affect the retina of a 

 human aphakic eye would therefore be about 4 minutes, providing 

 that the eye was close enough for the formation of a distinct image, 

 and ignoring the blurring due to the lessened refraction of an aphakic 

 eye. The absorption of the cornea is allowed for in this calculation, 

 since in the experiments the light passed through the cornea, but the 

 general absorption of the vitreous humor is not. Assuming this to 

 be about the same as that of the cornea (although it probably ii'- 

 greater) the calculated exposure would be increased to about 6 minutes. 

 Since beyond 1^ meters, owing to the small size of the source, the 

 intensity of the light on the retina would diminish as the square of the 

 distance, it is safe to say that under the most favorable conditions, it 

 would require fixation of the bare magnetite arc at a distance of 3 

 meters for almost | hour to injure the retina of an aphakic eye. 

 According to our experiments on the effects of repeated exposures 

 (page 641) a daily total exposure of 5 the liminal, which in the present 

 case would be 8 minutes at a distance of 3 meters from the mag- 

 netite arc, would produce pathological effects in the retina of the 



