Title: Fixational eye movements and fluctuations of accommodation: new roles for microsaccades?
30 March 2017, 11h00, room Y506 (Byron building)
Abstract: Among fixational eye movements (FEMs) occurring during visual fixation, microsaccades have been shown to counteract visual fading and help to scan informative regions. I will present two recent and undergoing investigations. First, the existence and potential role for monocular microsaccades, which differ in frequency during fixation vs foveal discrimination and according to the visibility of the stimulus, but also according to the eye-dominance. These results, lead to the hypothesis that monocular microsaccades might be triggered either to correct for small vergence error or to recenter a target’s stimuli at the preferred retinal locus of fixation. The theoretical and neurophysiological but also clinical implications of these unilateral eye movements will be discussed. Second, another ocular mechanism is active during visual fixation: microfluctuations of accommodation (MFs), for which only limited progress has been made in understanding its role in accommodation or perception. I will present early work showing 1) large epochs of synchrony between MFs and FEMs 2) that microsaccades appear to correct the lag of accommodation by an accommodative bump. This sustained shift bringing the retinal image into improved focus, might thus provide a precious time window for sampling high spatial frequency retinal content.