# Development and pilot evaluation of a binocular virtual reality Headset-Based pupillometer for quantitative assessment of pupillary light reflexes

## TL;DR

A new VR headset-based tool was developed to objectively measure eye responses to light, offering a more accurate way to detect optic nerve issues.

## Contribution

A novel VR headset-based pupillometer was developed and tested for objective RAPD assessment.

## Key findings

- Patients with optic neuropathy showed significantly reduced direct pupillary constriction compared to healthy controls.
- The VR pupillometer achieved high diagnostic accuracy with an AUC of 0.903 for absolute RAPD scores.

## Abstract

Relative afferent pupillary defect (RAPD) is a key sign of optic neuropathies but is traditionally assessed subjectively. Virtual reality (VR) headsets with integrated binocular eye tracking enable simultaneous measurement under standardized illumination. We developed and conducted a pilot evaluation of a VR headset–based pupillometer that objectively quantifies RAPD using advanced pupil-tracking and automated blink-correction algorithms. This proof-of-concept study enrolled 17 patients with unilateral optic neuropathy (glaucomatous, traumatic, ischemic, or inflammatory) and 30 healthy controls. A VR headset (FOVE®, Tokyo, Japan) recorded binocular pupillary responses at 120 Hz under photopic (~ 130 lx) and scotopic (< 1 lx) conditions. Two protocols captured direct and consensual light reflexes and simulated the swinging flashlight test. Measured parameters included minimum and maximum diameters, constriction percentage, constriction/dilation velocities, and logarithmic RAPD scores. Receiver operating characteristic (ROC) analysis assessed diagnostic accuracy relative to clinical RAPD grading. Patients exhibited significantly reduced direct constriction (26.3% vs. 47.8%; p < 0.001), slower dilation velocity, and higher absolute RAPD scores (2.46 ± 2.00 vs. 0.27 ± 0.25 log units; p < 0.001) than controls. ROC analysis demonstrated an area under the curve (AUC) of 0.903 for the absolute RAPD score, corresponding to 87% sensitivity and 91% specificity. The VR headset–based pupillometer objectively quantified RAPD by simultaneously recording direct and consensual responses. Given its high diagnostic accuracy, portability, and ease of use, this study provides preliminary evidence supporting the feasibility of VR-based pupillometry as an objective, reproducible alternative to conventional subjective testing for evaluating optic neuropathies.