# Technical validation of a virtual reality-based eye tracker for neuro-ophthalmic assessment: a reliability and reproducibility study

## TL;DR

This study tests a new VR-based eye tracker for neuro-ophthalmic assessments, finding it reliable and comfortable for users.

## Contribution

The study introduces and validates a new VR-based eye tracker (BulbiCAM) for neuro-ophthalmic testing.

## Key findings

- BulbiCAM showed high reproducibility for pupil and pursuit tests but lower reliability for saccade metrics.
- Key pupillometric parameters showed strong agreement between BulbiCAM and PupilLabs Neon.
- Most participants found the test comfortable with no eye strain or fatigue.

## Abstract

Virtual Reality (VR) eye trackers provide portable and objective tools for neuro-ophthalmic testing. This study aimed to assess the reliability and reproducibility of an emerging VR-based eye tracker (BulbiCAM) in healthy participants and compare its utility to an existing wearable eye-tracking system (PupilLabs Neon), thereby laying the groundwork for the future studies of clinical feasibility. Thirty-nine healthy participants underwent BulbiCAM testing across two visits, with inter-visit reproducibility evaluated using intra-class correlation coefficients. Pupillary light reflex assessments were conducted with both devices, allowing paired comparisons. Participant feedback demonstrated high acceptability, with 89% reporting the test as comfortable and 81.5% experiencing no eye strain or fatigue. BulbiCAM showed high reproducibility for pupil and pursuit tests (ICC = 0.76–0.88), though saccade reproducibility was lower (ICC = 0.46–0.62) which indicates limited reliability for saccade metrics. Key pupillometric parameters showed strong agreement between devices, with minimal bias observed in baseline diameter (-0.48 mm), peak constriction (-0.56 mm), constriction velocity (0.22 mm/s), and duration (-0.052 s). These findings support the potential clinical feasibility and reliability of BulbiCAM for both research and patient testing, offering a promising alternative for objective neuro-ophthalmic assessment.

The online version contains supplementary material available at 10.1038/s41598-025-30773-0.