Responses to a series of vertical movements of the
eyes were recorded at 3 minute intervals for 45
minutes. Between measurements subjects were
instructed to remove themselves from the chin rest
and look in the direction of the light panel. Fifteen
minutes of exposure to room light of approximately
500 lux was followed by 15 minutes of dark adaptation
and then by 15 minutes of light adaptation to 1200
lux. Because the pupils were not artificially dilated
actual retinal illumination could not be calculated.