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Silvio P. Sabatini, Agostino Gibaldi; Robust and Repeatable Approaches to Oculomotor Performance. Journal of Vision 2020;20(11):1062. doi: https://doi.org/10.1167/jov.20.11.1062.
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© ARVO (1962-2015); The Authors (2016-present)
Saccades are rapid ballistic eye movements that humans make to direct the gaze to an object of interest. The kinematics of healthy eye movements is well defined by a regular relationship between amplitude, duration and velocity, defined as the saccadic 'main sequence'. This relationship can be employed as a ready-to-use diagnostic tool to assess the integrity of the saccadic system. In fact, deviations of eye movements from the main sequence can be used as markers of specific neurological disorders. Despite its diagnostic significance, there is no consensus on the methodologies to obtain reliable and repeatable measurements of the main sequence.
In this work, we propose a novel approach for standard indicators of oculomotor performance. The approach relies on two complementary parts: 1) a model saccade profile is used to provide robust and objective measurements of saccade kinematics, then 2) model fitting is used to provide a compact one-parameter characterization of oculomotor performance. The experimental procedure consists in a non-fatiguing and user-friendly task, like a free exploration of natural images.
The obtained measurements show high repeatability, allowing for fine assessments of inter- and intra-subject variability, but also inter-ocular differences. The robustness of the model approach provides measurements that are relatively insensitive to the eye-tracking sampling frequency (down to 50Hz), thus allowing the use of low-cost technologies for a precise characterization of oculomotor performance. The limited invasiveness makes the method suited for fragile or non-collaborative subjects like neurological patients and infants. The method is released as a software toolbox for public use.
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