Reliability assessment of iPhone-based pupillometry: A test-retest analysis

Objectives: The objective of this study was to assess the test-retest reliability of an iPhone-based pupillometer, specifically the Reflex-pro pupillary light reflex (PLR) analyzer application, in measuring various pupillary parameters. The study aimed to evaluate whether this smartphone-based tool can provide consistent and reliable measurements across two different testing sessions, which is crucial for its potential use in clinical and research settings. Material and Methods: Forty participants (80 eyes) were recruited. The Reflex-pro PLR analyzer application provided a quantitative method for assessing pupil size and reactivity. Pupillary parameters were measured twice, and the intraclass correlation coefficients (ICCs) were calculated to assess measurement consistency between sessions. Results: The ICC for average constriction speed was 0.99 (0.98–0.99 CI), indicating excellent reliability. Limits of agreement were as follows: average constriction speed: 0.08 mm/second, constriction time: 0.09 seconds, maximum constriction speed: 0.03 mm/second, amplitude: 0.02 mm, average diameter: 0.02 mm, latency: 0.01 seconds, maximum diameter: 0.004 mm, minimum diameter: 0.03 mm. Most differences fell within the acceptable range, demonstrating good agreement between test and retest measurements. Conclusion: Our findings support the growing evidence that smartphone-based pupillometry is a reliable tool for measuring pupillary responses.