Adaptation of the pupil light reflex

Abstract

The consensual photopupil responses to light flashes presented in uniform illumination to the entire visual field were recorded in full dark adaptation, over a gamut of intensities of ganzfeld backgrounds and in the dark after full bleach of all visual pigment in the retina. The equivalent background of such bleaching was found to be valid not only at the photopupillomotor threshold but also for flashes several log units suprathreshold (as judged by matching of the waveform of the pupillomotor response). The pupillomotor equivalent background is in reasonable agreement with its psychophysical counterpart, suggesting that the neural pathways for vision and photopupillary motion are common, at least to the level that retinal sensitivity adjustment in dark and light adaptation has been achieved.