16 Pupil light response as a digital biomarker of recent cannabis consumption

Oregon Convention Center 

Marijuana is now legal for recreational or medical use in 41 states. Due to long-standing federal restrictions on cannabis-related research, the implications of cannabis legalization on traffic and occupational safety are understudied. There is a need for objective and validated measures of acute cannabis impairment that may be applied in public safety and occupational settings, such as post-crash or accident investigations. Identifying a reliable, objective biomarker of recent cannabis use has proven challenging, but pupillary response to light may offer an avenue for detection that outperforms typical sobriety tests. We developed a video processing and functional data analysis pipeline examining the pupillary response to a light stimulus test administered with goggles utilizing infrared videography. We then developed functional data models to make inference on pupil size in response to light after cannabis use. Our results suggest that functional regression models of pupil light response trajectories are more sensitive to differences across marijuana use groups than scalar feature extraction approaches.