The pupillary light reflex (PLR) as a marker for the ability to work or drive - a feasibility study.

Background: The PLR (pupillary light reflex) can be a marker for pathological medical conditions, such as neurodegenerative or mental health disorders and diseases as well as marker for physiological alterations, such as age, sex or iris color. PLR alterations have been described in people after alcohol consumption, as well. However, the effect of sleep deprivation on PLR parameters is still under debate.

Methods: The aim of this study was to investigate the feasibility of PLR measurements in sleep-deprived and alcohol-exposed participants. In addition, we wanted to identify PLR parameters that were altered by sleep deprivation and alcohol exposure.

Results: Altogether n = 50 participants have been included in this study. Differences in the PLR parameters initial diameter (d_init), latency (∆t_lat), acceleration (∆t_a), contraction velocity (ϑ_con), quarter dilatation velocity (ϑ_1/4dil), half dilatation time (∆t_1/2), and the line integral (L(0.3500)) have been evaluated between baseline, sleep deprivation, as well as alcohol exposure. In a generalized linear mixed models design, we could observe statistically significant associations between the type of exposure and the PLR parameters half dilatation time and half dilatation time after the first light pulse (all p < 0.05). The participants' latency showed a significant association in dependence of the type of exposure after the second light pulse (p < 0.05).

Conclusion: Our study delivers first promising results to further develop devices that may identify conditions that impair the ability to work or drive.