Atypical eye movements and postural control in Autism Spectrum Disorders (2017)
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Hypothesis: Research shows a link between pursuit eye movements, visual processing, and postural control; current evidence suggests these links are different in individuals with Autism Spectrum Disorder (ASD). For those with ASD, few studies quantitatively examine visuomotor integration and its influence on postural stability. The purpose of this study was to observe individuals with ASD and those with typical development (TD) in order to identify and characterize differences in how visual information and eye movement are used for postural control. Materials/Methods: This study was conducted in community sites in the Dallas-Fort Worth metroplex. Five adolescents with ASD and 5 age matched TD controls completed the study. The experiment consisted of balance testing, including the Limits of Stability (LOS) and The Clinical Test for Sensory Integration (CTSIB), on a force plate while wearing the ETG 2.0 eye tracking system. The CTSIB requires quiet standing with eyes open, eyes closed, and wearing a translucent dome. The LOS requires a shift in center of pressure (CoP) to reach 9 target positions displayed on the screen. Data were analyzed with t-tests. Results: ASD adolescents had higher sway and stability indices than TD across all conditions of the CTSIB. During LOS testing the ASD group had lower postural control than the TD group in 5 of the 9 target positions. Overall, ASD group took a longer time to complete the task, which is a proxy for movement accuracy, since the task advances when participants meet “hit” criteria for each target. Pursuit eye movements and stabilization of targets showed greater variability in ASD group compared to TD. Moreover, the ASD participants did not improve their performance across the 3 trails of the LOS. Conclusions: These preliminary data support our hypothesis that individuals with ASD would have greater postural instability than TD controls. These impairments may be linked to increased variability and less accuracy of pursuit eye movements. When visual context was eliminated, individuals with ASD demonstrated markedly greater impairment in stability. When LOS were tested, the ASD group showed greater difficulty maintaining postural control during CoP shift. Preliminary eye movement data suggests that atypical gaze patterns relate to impairments in stability. Further studies are necessary to investigate this atypical visiomotor integration and its possible role as a fundamental feature of ASD.