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The influence of oculomotor tasks on postural control in dyslexic children
Maria Pia Bucci1, Damien Mélithe1, Layla Ajrezo1
1UMR 1141, INSERM-Université Paris 7, Hôpital Robert Debré Paris, France.
Insights
Dyslexic children exhibit poorer postural stability and visual-motor control compared to non-dyslexic peers, particularly during demanding visual tasks. These findings suggest underlying neurological differences affecting attention and balance in dyslexia.
Area of Science:
- Neuroscience
- Developmental Psychology
- Ophthalmology
Background:
- Dual-tasking significantly impacts postural stability in children.
- Dyslexia is associated with various neurodevelopmental differences, including potential oculomotor and cerebellar impairments.
Purpose of the Study:
- To investigate the effect of visual tasks on postural control in dyslexic children.
- To compare postural stability and oculomotor performance between dyslexic and non-dyslexic children.
Main Methods:
- Thirty dyslexic children and two control groups (chronological and reading age-matched non-dyslexic children) participated.
- Ophthalmologic and optometric evaluations were conducted.
- Eye movements (fixations, pursuits, pro- and anti-saccades) and postural sway were simultaneously recorded using video-oculography and a force platform.
Main Results:
- Dyslexic children demonstrated significantly weaker near fusional vergence ranges (convergence and divergence).
- Postural task performance showed poorer fixation quality and anti-saccade accuracy in dyslexic children compared to controls.
- Dyslexic children exhibited greater postural instability than age-matched controls, and saccadic tasks (pro- and anti-saccades) reduced postural sway across all groups.
Conclusions:
- Impaired vergence capabilities in dyslexic children may stem from immature cortical structures.
- Deficits in visual attention allocation and postural instability in dyslexia align with reported oculomotor and cerebellar impairments.
- Visual tasks with higher attentional demands (saccades) differentially influence postural control, highlighting the interplay between visual processing and balance.
Abstract:
Dual task is known to affect postural stability in children. We explored the effect of visual tasks on postural control in thirty dyslexic children. A selected group of thirty chronological age-matched non-dyslexic children (mean age: 9.92 ± 0.35 years) and a group of thirty reading age-matched non-dyslexic children (mean reading age: 7.90 ± 0.25 years) were chosen for comparison. All children underwent ophthalmologic and optometric evaluation. Eye movements were recorded by a video-oculography system (EyeBrain® T2) and postural sway was recorded simultaneously by a force platform (TechnoConept®). All children performed fixations, pursuits, pro- and anti-saccades tasks. Dyslexic children showed significantly poor near fusional vergence ranges (convergence and divergence) with respect to the non-dyslexic children groups. During the postural task, quality of fixation and anti-saccade performance in dyslexic children were significantly worse compared to the two non-dyslexic children groups. In contrast, the number of catch-up saccades during pursuits and the latency of pro- and anti-saccades were similar in the three groups of children examined. Concerning postural quality, dyslexic children were more unstable than chronological age-matched non-dyslexic children group. For all three groups of children tested we also observed that executing saccades (pro- and anti-saccades) reduced postural values significantly in comparison with fixation and pursuit tasks. The impairment in convergence and divergence fusional capabilities could be due to an immaturity in cortical structures controlling the vergence system. The poor oculomotor performance reported in dyslexic children suggested a deficit in allocating visual attention and their postural instability observed is in line with the cerebellar impairment previously reported in dyslexic children. Finally, pro- or anti-saccades reduce postural values compared to fixation and pursuit tasks in all groups of children tested, suggesting a different influence of visual tasks on postural control according to their attentional demand.
