Task and field dependence of objective measurements of fixational eye motion measured with tracking scanning laser ophthalmoscopy in healthy controls

Abstract

Purpose : The purpose of this study was to compare tracking scanning laser ophthalmoscopy (TSLO) measurements of fixational eye motion (FEM) with two different tasks at two different imaging field sizes. 10-second recordings were acquired and microsaccade and drift parameters of FEM were extracted and compared for healthy control subjects.

Methods : Twenty-three young, healthy control subjects (13 male, 10 female) aged 23-31 participated in the study. At least three, 10-second videos of the subjects fixating the upper right hand corner and a blinking dot in the center of a 5° 840nm imaging raster for each eye were acquired on two separate days separated by one week. On the second day, videos were also acquired at and 2.5°. Offline, custom Matlab software was used to stabilize the images, extract eye motion at 480 Hz, and compute FEM characteristics: microsaccade number, amplitude, peak velocity, and peak acceleration, and drift amplitude and drift ratio. One-way ANOVA analysis compared FEM characteristics across conditions.

Results : There were statistical differences found for most FEM characteristics between the two field sizes: microsaccade number, amplitude, peak velocity, and peak acceleration (P<0.001), microsaccade duration (P=0.01), drift amplitude (P=0.002), and drift proportion (P<0.001). For fixation conditions, there were small statistically significant differences were seen in peak velocity (P=0.01) and peak acceleration (P=0.02). For the 5° field size, no statistical differences were found between days. Small significant differences were found between eyes for subset of variables, but these differences went away when controlling for day.

Conclusions : FEM characteristics measured with TSLO differed for measurements made with different field sizes. There were only small or no significant differences with task, eye, and across days for FEM characteristics. Future work will continue to see if these differences are due to some underlying mechanism or if there is a way to translate results from one field size to another to allow comparisons in future clinical studies.

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