A New Method to Explore the Modulation from the Saccadic System on the Pupillary Light Reflex System

The saccadic system has anatomical and functional connections with the pupillary light reflex (PLR) system. But it is not known whether the saccadic system modulates the PLR system. To investigate this issue, it is necessary to know whether the uneven light stimulus to retina and the near responses influence the change of pupil diameter. We designed a new behavioral method to investigate the issue on human subjects. Methods: one eye of the subject was stimulated by pulse light stimulus from a horizontal linear array of light emitting diodes (LEDs) presented across visual field in an ocular mask. The changes of the eye position and pupil diameter of another eye were recorded by an infrared eye tracking system. Results: The relative constriction ratios of PLRs when the fixation points of subjects were in the nasal visual field were not significantly different from them when the fixation points of subjects were in the temporal visual field(P=0.148, Non-paired t test).Conclusion: The influences from uneven light stimulus to retina and the near responses were eliminated by this method. The method can be used to study the modulation from the saccadic system on the pupillary light reflex system.