Figure 4.

Web browser pupillometry experiment. A, Experimental setup for running the PLR stimulation and in the meantime performing pupillometric recordings. The PC is connected to the Internet by running an instance of the MEYE tool in the web browser. A USB camera, equipped with an IR light source, is focused on the eye of the subject. The photic stimulus is delivered using an LED array driven by an Arduino Due microcontroller board. The Arduino Due board is connected to the PC, emulating a keyboard and sending keystroke stimulus triggers to the MEYE tool. B, A picture of MEYE GUI. The subject during the recording is visualized as a streaming video. An ROI is used to locate the eye, and a preview of the estimation of the pupil is superimposed on the image of the subject. The GUI allows to set different parameters of postprocessing (map thresholding and refinement via mathematical morphology). C, Raw trace of the experiment (blue). Dashed lines locate the onset of flash stimuli. The green rectangles locate the onset and duration of blinks. The samples corresponding to blinks are removed and linearly interpolated (in red). D, Average event-related transient to flash stimulation in raw values. After the onset of the stimulus (dashed line), a strong constriction of the pupil is observed (44.53%). E, The z-score of the average event-related transient seen in D. The average nadir amplitude is 14.59 SDs from baseline.