Abstract
The spectrally adjustable Ocular Photosensitivity Analyzer (saOPA) is a new automated instrument utilized to quantify the visual photosensitivity thresholds (VPT) in healthy subjects with good vision. The saOPA generates light stimuli of varying intensities utilizing unequal ascending and descending steps to yield the visual photosensitivity threshold. The saOPA can emulate distinct light sources such as LED, incandescent and sunlight. Catch trials were integrated within the saOPA psychophysical testing paradigm as a performance metric to measure the response reliability of the subject during the OPA VPT measurement session.
The pilot saOPA study (n=12 ) revealed that the device can reliably measure VPT in healthy subjects, and the optimal rest period between tests is 10 minutes. The saOPA pilot study also revealed that VPT can significantly increase VPT) by using 476nm spectral filter.
The main saOPA study (n=44) sheds light on the intricate relationship between specific wavelengths of light and visual photosensitivity threshold (VPT), revealing important insights into its modulation. The findings underscore the moderating role of blue wavelengths in VPT when effectively filtered, with spectral filters at 456 and 476nm significantly increasing VPT . Moreover, the influence of green and red light emerges as a significant factor in moderating the overall effect of light sources (LED, incandescent, and solar). Factors such as macular pigment optical density (MPOD), skin color, and iris color emerge as substantial mediators in the effects of filters and light modes, hinting at a complex interplay between biological factors and environmental stimuli. Changes in pupil constriction (constriction rate and maximum) serve as a reflective marker of differences in VPT, revealing the nuanced nature of light sensitivity under varying conditions.