High-Resolution Eye-Tracking System for Accurate Measurement of Short-Latency Ocular Following Responses (Preprint)

BACKGROUND Ocular following responses (OFRs), small amplitude short-latency reflexive eye movements, have been used to study visual motion processing, with potential diagnostic applications. However, they are difficult to record with commercial video-based eye trackers, especially in children. OBJECTIVE We aimed to design and develop an eye tracker specialized for measuring OFRs, trading off lower temporal resolution and a smaller range for higher spatial resolution. METHODS We developed a high-resolution eye and head tracking system based on a high-resolution camera operating in the near-infrared spectral range, coupled with infrared illuminators and a dedicated post-processing pipeline, optimized to measure OFRs in children. To assess performance, we: (1) evaluated our head-tracking algorithm's resolution in artificial and real-use settings, (2) compared OFRs measured simultaneously with our system and a scleral search coil in an experienced adult, and (3) tested the system's ability to measure OFRs in a clinical setting in children. RESULTS Using artificial and in-vivo calibration techniques we found that our system has an in-vivo resolution of approximately 0.06°, which is sufficient for recording OFRs. Our system successfully measured OFRs in 16 children in short recording sessions lasting less than 5 minutes. Robust OFR responses were detected in all 16 subjects using the system presented. CONCLUSIONS Our system effectively addresses the limits of other OFR measurement methods and offers a versatile solution suitable for clinical applications, particularly in children where eye-tracking is more challenging.