High-resolution eye-tracking via digital imaging of Purkinje reflections

Abstract

Reliably measuring eye movements and determining where the observer looks are fundamental needs in vision science. A classical approach to achieve high-resolution oculomotor measurements is the so-called dual Purkinje image (DPI) method, a technique that relies on the relative motion of the reflections generated by two distinct surfaces in the eye, the cornea and the back of the lens. This technique has been traditionally implemented in fragile and difficult to operate analog devices, which have remained exclusive use of specialized oculomotor laboratories. Here we describe progress on the development of a digital DPI, a system that builds on recent advances in digital imaging to enable fast, highly precise eye-tracking without the complications of previous analog devices. This system integrates an optical setup with no moving components with a digital imaging module and dedicated software on a fast processing unit. Data from both artificial and human eyes demonstrate subarcminute resolution at 1 kHz. Furthermore, when coupled with previously developed gaze-contingent calibration methods, this system enables localization of the line of sight within a few arcminutes.

Perceptual consequences of retinal stabilization with a high-frequency LCD display

“…1A bottom). In both conditions, eye movements were continually recorded by means of a high-resolution dual Purkinje Image eye-tracker (12), a system that provides arcminute resolution with 1 ms delay.…”

“…The subject’s head was immobilized by a dental imprint bite-bar and a headrest to maintain a fixed distance of 123 cm from the monitor. Movements of the viewing eye were measured by custom digital Dual Purkinje Image (DPI) eye-trackers (12). Stimuli were rendered using EyeRIS, a system for gaze-contingent display control that enables real-time synchronization between oculomotor measurements and the updating of the image on the monitor (15).…”

High refresh rate display for natural monocular viewing in AOSLO psychophysics experiments

“…7-the trackable range could potentially be expanded to cover the whole field of view of the monitor. Highresolution Dual-Purkinje Image (DPI) eye-trackers achieve trackable ranges between +/-10 degrees and +/-25 degrees with arcminute uncertainty [58,59], but these eye-trackers rely on external calibrations to determine the position of the line of sight in the world rather than tracking retinal movement directly. TSLOs can achieve a trackable range around +/-3 degrees by trading off spatial resolution with field of view, but these systems lack the resolution for simultaneous cone imaging in the central fovea [24].…”

Open Iris - An Open Source Framework for Video-Based Eye-Tracking Research and Development

“…An example of externally developed plugins is provided by the independent contributor (second author), who has developed a dual-Purkinje eye tracking pipeline for OpenIris that detects reflections of the illuminator from the cornea surface and the inner surface of the lens (Figure 3a). [Wu et al, 2023]…”

“…[Otero-Millan et al, 2015] An example of externally developed plugins is provided by the independent contributor (second author), who has developed a dual-Purkinje eye tracking pipeline for OpenIris that detects reflections of the illuminator from the cornea surface and the inner surface of the lens (Figure 3a). [Wu et al, 2023] 2.2.3 Calibration pipelines. The main function of calibration pipeline plugins is to establish a mapping between the features extracted by the tracking pipeline and the actual motion of the eye.…”