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

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.