Eye Tracking in Ocular Proton Therapy

Optical eye tracking solutions can play a role in patient alignment and real-time monitoring of the eye movements during ocular proton therapy (OPT) and replace the current clinical standard based on radiographic imaging of surgical clips implanted in the patient's eye. The aim of this study is to compare the performance of an eye tracking solution specifically developed for OPT applications to this clinical standard. The eye tracking system (ETS) was used to pre-align the patient to the treatment position using information based solely on the pupil position before correction administered through X-ray imaging. As a result, we compared the geometrical accuracy achieved with the ETS to X-ray imaging of clips. In addition, we evaluated the ability of the ETS in determining the real position of the pupil through a comparison with a geometrical eye model. Pupil-based patient alignment performed, on average, worse than the conventional approach based on clips and a patient-specific bias was observed in the assessment of the pupil center position between ETS and the eye model. The limited accuracy of the ETS id due to the adoption of a simplified eye tracking approach and current investigation are focused into integrating gaze direction estimation in the process.