# Eye Tracker Accuracy: Quantitative Evaluation of the Invisible Eye Center Location

## TL;DR

This paper introduces a novel method using an artificial eye phantom and a kinematic model to accurately evaluate eye tracker localization, demonstrating sub-millimeter precision suitable for eye intervention applications.

## Contribution

The paper presents a new validation approach for eye tracker accuracy using a realistic eye phantom and a kinematic model, enabling precise 3D eye center localization evaluation.

## Key findings

- The testing stage with the kinematic model is effective for validation.
- The eye tracker achieves sub-millimeter accuracy in locating the eye center.
- The method supports improvements in eye-tracking navigation systems.

## Abstract

Purpose. We present a new method to evaluate the accuracy of an eye tracker based eye localization system. Measuring the accuracy of an eye tracker's primary intention, the estimated point of gaze, is usually done with volunteers and a set of fixation points used as ground truth. However, verifying the accuracy of the location estimate of a volunteer's eye center in 3D space is not easily possible. This is because the eye center is an intangible point hidden by the iris. Methods. We evaluate the eye location accuracy by using an eye phantom instead of eyes of volunteers. For this, we developed a testing stage with a realistic artificial eye and a corresponding kinematic model, which we trained with {\mu}CT data. This enables us to precisely evaluate the eye location estimate of an eye tracker. Results. We show that the proposed testing stage with the corresponding kinematic model is suitable for such a validation. Further, we evaluate a particular eye tracker based navigation system and show that this system is able to successfully determine the eye center with sub-millimeter accuracy. Conclusions. We show the suitability of the evaluated eye tracker for eye interventions, using the proposed testing stage and the corresponding kinematic model. The results further enable specific enhancement of the navigation system to potentially get even better results.