Figure 7.
Exposure to intermittent light enhances pupillary constriction responses. A, The pupillary light reflex is shown in sighted participants (n = 6) during exposure to 30 min of continuous green light (gray trace) versus intermittent green light at 1 Hz (black trace) using an LCD monitor. Intermittent light (12 log photons cm−2 s−1) elicited pupillary constriction responses that were sustained and twice as great relative to exposure to continuous light at the same irradiance level. Error bars indicate SEM. B, Data from A are rebinned and plotted on a logarithmic scale. Pupil diameter increased monotonically during exposure to 30 min of continuous green light (gray circles), whereas intermittent green light prevented pupillary escape (black circles). C, Median pupillary constriction was ∼25% during exposure to 30 min of continuous light, whereas intermittent light elicited pupillary constriction responses >50% in the frequency range from 0.1 to 4 Hz. D, Spectral characteristics are shown for the LCD green light stimulus.