Normal saccades but decreased fixation stability in a population of children with dyslexia

Authors

  • Gro Horgen Vikesdal University of South-Eastern Norway, Norway
  • Helle Kristine Falkenberg University of South-Eastern Norway, Norway
  • Mark Mon-Williams University of Leeds, UK
  • Patricia Riddell University of Reading, UK
  • Trine Langaas University of South-Eastern Norway, Norway

DOI:

https://doi.org/10.5384/sjovs.v14i2.137

Keywords:

eye movements, dyslexia, saccades, fixations

Abstract

Developmental dyslexia affects around 5-15% of the population and has a heterogeneous aetiology. Optometric disorders are more prevalent in dyslexic populations but the relationship be- tween eye movement control and dyslexia is not well established. In this study, we investigated whether children with dyslexia show saccadic or fixation deficits and whether these deficits are related to deficits in visual acuity and/or accommodation. Thirty-four children with and without dyslexia were recruited for the project. All participants had an optometric examination and performed a saccade and fixation experiment. We used two eye movement paradigms: the step and the gap task. Eye movements were recorded by an infrared eye-tracker and saccade and fixation parameters were analysed separately. Saccadic latencies, premature saccades, and directional errors were similar between children with dyslexia and typically developing children. In contrast, fixations were significantly less stable in the dyslexic group. Neither saccades nor fixations were associated with deficits in accommodation or visual acuity. Children with dyslexia showed no difficulties in saccadic performance, but their fixation stability was reduced compared to the control group. The reduced fixation stability can be explained by general deficits in the cognitive processes that underpin eye movement control, that have also been found in other neuro-developmental disorders.

Author Biographies

Gro Horgen Vikesdal, University of South-Eastern Norway, Norway

Department of Optometry, Radiography and Lighting Design, National Centre for Optics, Vision and Eye Care, University of South-Eastern Norway

Mark Mon-Williams, University of Leeds, UK

Department of Optometry, Radiography and Lighting Design, National Centre for Optics, Vision and Eye Care, University of South-Eastern Norway

School of Psychology, University of Leeds, UK

Bradford Institute of Health Research, Bradford, BD9 6RJ, UK

Patricia Riddell, University of Reading, UK

Department of Psychology and Clinical Language Sciences, University of Reading, UK

Trine Langaas, University of South-Eastern Norway, Norway

Department of Optometry, Radiography and Lighting Design, National Centre for Optics, Vision and Eye Care, University of South-Eastern Norway

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Published

2021-12-31

How to Cite

Vikesdal, G. H., Falkenberg, H. K., Mon-Williams, M., Riddell, P., & Langaas, T. (2021). Normal saccades but decreased fixation stability in a population of children with dyslexia. Scandinavian Journal of Optometry and Visual Science, 14(2), 1–7. https://doi.org/10.5384/sjovs.v14i2.137

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