THE RELATION OF DARK ADAPTATION TO DURATION OF PRIOR RED ADAPTATION
Rept. no. 1
NAVAL MEDICAL RESEARCH LAB NEW LONDON CT
Pagination or Media Count:
The effects of duration of red preadaptation upon the immediate brightness threshold and upon the course of dark adaptation are presented. Measurements were made following seven adaptation periods of 0 to 40 minutes wearing red goggles under a preadapting brightness of 150 mL. It was found that red adaptation increased the rate of subsequent dark adaptation so that the 5 log micromicro L threshold was reached in one half the time after wearing red goggles for five minutes, and in one fourth the time after 20 minutes in red. Forty minutes in red gave no further decrease in dark adaptation time. In terms of the total time red plus dark required to dark adapt to a threshold of 5 log micromicro L, the first five minutes of red adaptation showed the greatest efficiency. Five minutes in red goggles followed by 3.8 minutes in darkness are equivalent to 8.2 minutes in darkness. Red preadaptation for long periods 20 minutes or more produces relatively little dark adaptation compared with the same time spent in total darkness. The sensitivity reached by wearing red goggles for 40 minutes was still 2.75 log micromicro L above the 30 minute threshold in total darkness.
- Anatomy and Physiology