DARK ADAPTATION
Going suddenly from bright light into darkness is a common occurrence.In such cases, the recovery of a previous maximum level of dark adaptation can take from 5 to 45 minutes in continued darkness.c. Dark adaptation for optimum night visual acuity approaches its maximum level in about 30 to 45 minutes under minimal light conditions.Vision with I2 devices is primarily photopic, but the low light levels produced by I2 devices do not fully bleach out rhodopsin.Brief flashes from a white (xenon) strobe light, commonly found on aircraft, have little effect on night vision because the pulses of energy are so short.If a previously dark-adapted crew member wearing an I2 device removes the device in a darkened environment, a 30-minute dark adaptation level can be regained in about two to three minutes.On the other hand, exposure to a flare, a searchlight beam, or lightning may seriously impair night vision.a. Dark adaptation is the process by which the eyes increase their sensitivity to low levels of illumination.d. Night vision devices affect dark adaptation.