X-IRRADIATION STUDIES ON THE MAMMALIAN RETINA 



551 



UJ 



> 60 



EARLY ERG DECLINE 



250 KV. 



525 rods /minute 



\ 



280 rods /minute 



175 rods /minute 



/ 



CONTINUOUS EXPOSURE 

 n--8 



MINUTES 



Fig. 8. The ERG decline resulting from 250 kvp irradiation. The dose delivered to 

 the posterior pole of the eye is 749f of that to the anterior rim of the retina, to which 

 the indicated dose rates refer. Start and rate of the ERG decline during continuously 

 applied irradiation are almost linearly related to dose rate. Termination of x-irradia- 

 tion prior to the start of the ERG decline, results in an incomplete effect occurring 

 with a maximal time lag of 4 to 5 minutes after the end of irradiation. 



PRE 



6 

 HOURS 



10 



I 2 



4 

 DAYS 



Fig. 9. ERG (b-wa\e) decline after 5,100 rads (medium retinal dose; 250 kvp). 

 Immediately following radiation, the b-wave becomes reduced by 50*?^, a slower de- 

 cline thereafter leads to its disappearance. 



