Effect of Primary Open-Angle Glaucoma on eye movement patterns during a fixation task using ultrafast experimental retinal eye tracker

Abstract

Purpose : Previous studies have shown that the fixational eye movements are affected in glaucoma, but the results are inconclusive. The aim of this study was to determine whether primary open-angle glaucoma (POAG) is associated with disturbances in fixation stability assessed by experimental retinal eye tracking system (NeuroFET) and whether the severity of glaucoma is related to a deterioration in these indicators.

Methods : This study analyzed fixation stability using NeuroFET, a unique, non-invasive optical device for measuring microssacades and drift, in patients with mild and moderate/severe POAG and healthy controls. The resulting fixation variables measured from 15s fixation recordings were correlated with retinal sensitivity evaluated by microperimetry (MP), and standard automated perimetry (SAP), retinal nerve fiber layer and ganglion cell layer thickness measured by optical coherence tomography (OCT), and vascular density in OCT angiography (OCTA). 66 subjects were enrolled to the study, including 33 POAG patients and 33 healthy subjects of similar age (±68). We successfully analyzed 66 eyes in the POAG groups (48 mild POAG, 18 moderate/severe POAG) and 65 eyes in the healthy group.

Results : It was shown that differences in fixation stability measured during 15s fixations were observed in the microsaccadic shapes, with POAG group manifesting higher lengths of saccades for the same saccadic amplitudes than the normal group. Differences in bivariate contour ellipse area (BCEA), including 95%/63% of fixation points, were not observed among groups. The correlations among fixation and abnormalities in retinal structural and functional parameters were confirmed in POAG group. The strongest correlations were observed between eye movement vertical trajectory length (V) and the superficial vascular plexus (SVP) r=-0.661, deep vascular plexus (DVP) and SVP ratio (DVP/SVP) r=0.534 and average threshold (AT) r=-0.676. Differences between groups were statistically significant (p < 0.05).

Conclusions : We concluded that POAG patients do not manifest differences in fixation stability measured with BCEA but show differences in the microsaccadic shapes which can be effectively assessed using NeuroFET. The correlations in POAG group among trajectory of the eye movements in the vertical axis and abnormalities in retinal structural and functional parameters were confirmed.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.