Opioid Detection Using Smartphone-Based Eye-Scanning.

Opioids are known to constrict pupils, and mobile phone-based self-administered eye scanning (MPSES) offers a potential method for monitoring opioid use in real-world settings. A clinical trial with 12 volunteers measured pupil size using MPSES under different light conditions (approx. 50 or approx. 500 lux) in the lab and over a week at home. Each participant made approximately 21 home tests, 12 in the lab without oxycodone and 16 in the lab after oxycodone intake. At the second visit the participants received a single dose of 20 mg oxycodone, and their pupil size was monitored hourly for 5 h. The pupil size after oxycodone intake was compared to drug-naïve tests performed at the lab and at home. Logistic regression models were built using measured pupil size and light conditions measured by the phone during each test, and a dichotomous variable indicating tests before or after oxycodone dosing as the outcome. The model demonstrated high classification accuracy (AUC = 0.94), with 82% true positives, 9% false positives, 91% true negatives and 18% false negatives. Misclassifications were largely due to difficulties measuring pupil size in individuals with corneal arcus, causing most of the false positive findings, and other interindividual differences. This shows that MPSES, including monitoring of ambient light conditions, can effectively detect opioid use within the 50-500 lux range. Our study paves the way for using MPSES to detect opioid use.