Calibration-free retinal-anterior eye-tracker for high-speed, high-accuracy, and high-precision eye movement estimation during fixations, saccades, and smooth pursuit

Eye-tracking is increasingly prevalent across various aspects of our lives. It is currently used for research, education, diagnostics, and entertainment, for example, in virtual reality goggles. However, widely used video-based eye-trackers require subject-dependent calibration, which makes them unsuitable for examining individuals with unstable fixation, such as patients with neurodegenerative diseases.

We present a novel calibration-free retinal-anterior eye tracker that uses retinal images to track changes in eye orientation. On an artificial eye, the eye tracker achieves an accuracy better than 0.6′ (0.01°) and a sample-to-sample precision of 0.09′ (0.0015°) for the reference-frame signal, improving to 0.05′ (0.0008°) after Kalman fusion. Under similar conditions, this precision exceeds that reported for video-based eye trackers.

After a one-point trajectory offset correction, the eye tracker enables determination of the absolute gaze direction.The eye-tracker was tested with an artificial eye over a traverse of − 8° to + 8°. In human recordings we typically work within approximately ± 4°, a practical limit based on operating experience rather than on a systematic characterization. The eye-tracker is capable of measuring saccadic velocities of up to 300 °/s, incorporates an integrated display for dynamic stimulus presentation, and requires only a simple chin- and forehead rest for subject stabilization.

The potential of this eye-tracker is demonstrated in healthy subjects and in participants who are unable to undergo a conventional calibration procedure. Additionally, the device is equipped with a synchronized video-based eye-tracker, making it a powerful research platform for developing eye-tracking technologies. The project was partially financed by the Foundation for Polish Science (POIR.04.04.00-00-2070/16 − 00) and the National Science Centre (2023/51/B/ST7/02787).

Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, 5 Grudziądzka St, Toruń, 87-100, Poland Marta K. Skrok, Patrycjusz Stremplewski, Szymon Tamborski, Valentyna Pryhodiuk, Michał Meina & Maciej Szkulmowski Institute of Advanced Studies, Nicolaus Copernicus University in Toruń, 4 Wilenska St, Toruń, 87-100, Poland Marta K. Skrok, Szymon Tamborski & Maciej Szkulmowski Inoko Vision, Mickiewicza 7/17, Torun, 87-100, Poland Robert Konklewski, Maciej Nowakowski, Jakub Lipiński & Anna Szkulmowska Lund University Humanities Lab, Box 201, Lund, SE–221 00, Sweden Marcus Nystrom & Diederick C.

Niehorster Experimental Psychology, Helmholtz Institute, Utrecht University, Heidelberglaan 1, Utrecht, 3584 CS, The Netherlands Department of Psychology, Box 201, Lund, SE–221 00, Sweden MNo, ASz, JL, and MSz are co-owners, and RK is an employee of Inoko Vision. DN and MNy are the full owners of eye-tracking consulting companies (DC Target AB and Emnys Consulting AB, respectively). The other authors declare no conflicts of interest.