Chapter

Movements of the Eyes in Three-Dimensional Space: Deficits of Vergence and Binocular Coordination in Dyslexia

Zoï Kapoula

in Visual Aspects of Dyslexia

Published in print August 2012 | ISBN: 9780199589814
Published online September 2012 | e-ISBN: 9780191744785 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199589814.003.0003
Movements of the Eyes in Three-Dimensional Space: Deficits of Vergence and Binocular Coordination in Dyslexia

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Rapid, accurate and well coordinated saccades of the two eyes are a prerequisite for clear vision particularly during reading. The Iris group has studied fixation stability and saccadic parameters in good and bad readers. Specific impairments in these are found in dyslexic children, namely fixation instability due to disconjugate drifts, reduced binocular coordination of saccades, and increased latencies. These eye movement features normally develop slowly, only achieving adult quality by the age of 12. The saccadic and vergence control systems which are separate in the brainstem need to interact precisely with each other. Thus defects in the vergence system may influence the quality of the binocular coordination of saccades. In dyslexics difficulty with achieving accurate binocular coordination can be seen as a sort of micro-dyspraxia, related to cerebellar and magnocellular misfunction. The next step is to develop appropriate training techniques and evaluate their benefits for reading.

Keywords: saccades; eye; vergence; binocular; reading; vision

Chapter.  7329 words.  Illustrated.

Subjects: Neuroscience

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