Analysis of fixation patterns among glaucoma patients using a superfast eye tracking system

Abstract

Aims/Purpose: The effect of glaucoma on eye movements is not well understood, so it is extremely important to be able to quantitatively characterize eye movement data which could accelerate glaucoma diagnosis. The aim of the study was to determine differences in eye movements among glaucoma patients and healthy subjects, using a superfast eye tracking system, FreezEye Tracker (FET).Methods: To study eye movements during a 30‐second fixation task, we used a prototype device FET, which was designed and assembled in our laboratory (Bartuzel et al., 2020). The unique capability of this device is to provide precise information (with an accuracy of about 1 μm on the retina) on eye movements during the fixation task (and other visual tasks) collected at high frequency (more than 1240 eye position measurements per second). We conducted a study on 13 glaucoma patients and 13 healthy subjects of similar age (69 ± 67). The participants' task was to look at the fixation point displayed in the centre of the screen for the period of 30 s.Results: During the fixation task, we reconstructed the trajectory of the eye movements (in the horizontal and vertical axis) and calculated area of the fixation points, called bivariate contour area (BVRCA) as a measure of fixation stability. Results show that in glaucoma patients the horizontal axis trajectory length (H) and BVRCA were smaller compared to healthy subjects. In glaucoma patients the avg. horizontal axis trajectory length was 60.91° [deg] and BVRCA parameter was 0.19°2. In a healthy group, the average horizontal axis trajectory length was 71.80° and BVRCA parameter was 0.36°2.Conclusions: The results of the study indicate that the glaucoma patients had greater fixation stability during the task, and their microsaccades showed smaller deviation from the centre of fixation, compared to healthy subjects. The results of the study show that the device has the potential to differentiate basic eye movement parameters in glaucoma patients and healthy subjects.Reference Bartuzel MM, Wróbel K, Tamborski S et al. High‐resolution, ultrafast, wide‐field retinal eye‐tracking for enhanced quantification of fixational and saccadic motion. Biomedical Optics Express, 2020, 11(6), 3164–3180.