Over two decades ago, a new type of photoreceptor was discovered. The intrinsically photosensitive retinal ganglion cells (ipRGCs), that are most sensitive around 480 nm. This photoreceptor has been found to be involved with non-image forming processes and enhanced cognitive performance. The aim of this research was to investigate to what extent stimulation of the ipRGCs affect the experienced visual comfort. In order to do so, a within-subjects design was used. Each participant was exposed to six different light stimuli that contained either a low, medium, or high level of ipRGC stimulation, at two illuminance levels. The two sets of light stimuli were metamers. For each set, light characteristics such as the color temperature and S, M, and L cone activation were the same, by method of silent substitution. To measure visual comfort a questionnaire was used, and pupil constriction was calculated per stimulus. For the subjective visual comfort data, there were 23 participants with complete data and for pupil constriction there were 22 participants, both between 19 and 25 years old. The data was analyzed separately by means of multi-level models. The results show that increases in ipRGC stimulation led to a decrease in the subjective visual comfort. In contrast, increases in ipRGC stimulation led to increases in pupil constriction. Pupil constriction and subjective visual comfort were negatively correlated.
Investigating the effect of ipRGC stimulation on the visual comfort of white light
Janssen, T. H. (Author). 26 Jun 2022
Student thesis: Bachelor