Figure 6.

Spectral responses of the pupillary light reflex (PLR). Comparison of the PLR to 480 and 620 nm monochromatic long-duration (5 min) stimulations at 6 different irradiances in a single subject. After the initial and rapid pupil constriction, the steady state equilibrium and the persistent responses are present in all except the lowest irradiances, thus depending on wavelength and light intensity. The amplitude of the steady state equilibrium response is rapidly attained and particularly robust at 480 nm for the highest irradiances used. The persistent responses are also greater at 480 nm, as compared to 620 nm at equivalent irradiances. Note that for the higher irradiances, the pupil has not yet returned to the baseline within 5 min after extinction of the stimulus (reproduced from [134]).