Pupillary Light Reflex induced by two-photon vision

The pupillary light reflex caused by an infrared stimulus, perceived through two-photon absorption in visual pigments, was compared with that evoked by visible light. The power of the visible stimuli was determined by a dedicated procedure to obtain the same perceived brightness equivalent to that used in two-photon stimulation. Two-photon stimulation produced a smaller pupillary reflex, probably because of weaker stimulation of the rods relative to the cones and lack of stray light perception.

The data set contains pupil diameter data (in pixels and in mm) recorded for 14 healthy dark-adapted subjects. Three types of 3.5-degree-diameter stimuli lasting 2 s were tested: spirals formed by fast-scanning laser beams at 1040 nm (IR laser) or 520 nm (VIS laser), and an uniformly filled circle formed by a 520 nm LED (VIS LED). Pupil diameter data were collected 10 s before the stimulus, during stimulus presentation, and 60 s after stimulation. Three trials were conducted for each stimulus type. The power of the IR laser beam at the pupil plane was about 800 uW.

The additional data are provided for three subjects: "P#_invisible" with pupil diameter data in case no stimulus and with IR laser stimulus under visibility threshold; "P#_equivalent" with pupil diameter data following VIS laser stimulus evoking similar reaction as registered for IR laser of power 800 uW.