  Eye-tracking plays a crucial role in the development of virtual reality
devices, neuroscience research, and psychology. Despite its significance in
numerous applications, achieving an accurate, robust, and fast eye-tracking
solution remains a considerable challenge for current state-of-the-art methods.
While existing reflection-based techniques (e.g., "glint tracking") are
considered the most accurate, their performance is limited by their reliance on
sparse 3D surface data acquired solely from the cornea surface. In this paper,
we rethink the way how specular reflections can be used for eye tracking: We
propose a novel method for accurate and fast evaluation of the gaze direction
that exploits teachings from single-shot phase-measuring-deflectometry (PMD).
In contrast to state-of-the-art reflection-based methods, our method acquires
dense 3D surface information of both cornea and sclera within only one single
camera frame (single-shot). Improvements in acquired reflection surface
points("glints") of factors $>3300 \times$ are easily achievable. We show the
feasibility of our approach with experimentally evaluated gaze errors of only
$\leq 0.25^\circ$ demonstrating a significant improvement over the current
state-of-the-art.
