Light stimulation system for measuring pupillary light responses based on Maxwellian view optical system using a retina presentation type viewfinder
Purpose: To evaluate the feasibility of applying a retinal projection viewfinder based on the Maxwellian view (MV) optical system for measuring post-illumination pupil response (PIPR) by comparing its performance with a typical LED-based optical system. Methods: Twenty-two healthy participants underwent pupillometry using both the MV-based viewfinder and a typical LED-based system. Monochromatic red and blue light stimuli were presented for durations of 1 and 10 seconds. Pupil responses, including maximum constriction, PIPR amplitude after 6 seconds from the light offset, area under the curve (AUC) values of PIPR, and sustained slopes, were analyzed using a linear mixed-effects model to assess the differences between the two systems. Results: The MV-based viewfinder significantly enhanced net PIPR amplitude (p < 0.05) and sustained slope (p < 0.01) during 10-second light stimulation compared to the LED system, demonstrating its capability to effectively measure ipRGC-driven responses. In contrast, no significant differences were observed in the net AUC values. These results highlight that the MV-based viewfinder enables effective PIPR measurements by delivering constant and controlled light stimulation directly to the retina, minimizing the effects of dynamic pupil constriction during light stimulation. Conclusions: The MV-based viewfinder showed feasibility as an effective method for measuring PIPR without requiring pharmacological dilation and technical knowledge to build the MV system. This innovative approach has significant potential for clinical and research applications in pupillometry. Translational Relevance: Our methodology provides practical solutions for dilation-free effective measurement of PIPR, accelerating its translation from experimental tool to routine clinical diagnostic.