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Journal of Ophthalmology
Volume 2009 (2009), Article ID 325214, 8 pages
http://dx.doi.org/10.1155/2009/325214
Clinical Study

Normal Speed and Accuracy of Saccade and Vergence Eye Movements in Dyslexic Reader Children

1FRE 3292 CNRS, Université René Descartes Paris V, 71 avenue Edouard Vaillant, 92774 Boulogne Billancourt Cedex, France
2FRE 3154 CNRS, Pôle Chirurgie ORL-OPH, Hôpital Robert Debré, 48 boulevard Sérurier, 75019 Paris, France
3Service de Psychopathologie de l'Enfant et de l'Adolescent, Hôpital Robert Debré, 48 boulevard Sérurier, 75019 Paris, France

Received 4 May 2009; Revised 7 September 2009; Accepted 19 October 2009

Academic Editor: Pierre Lachapelle

Copyright © 2009 Maria Pia Bucci et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. Latency of eye movements depends on cortical structures while speed of execution and accuracy depends mostly on subcortical brainstem structures. Prior studies reported in dyslexic reader children abnormalities of latencies of saccades (isolated and combined with vergence); such abnormalities were attributed to deficits of fixation control and of visual attention. In this study we examine speed and accuracy characteristics of horizontal eye movements in natural space (saccades, vergence and combined movements) in dyslexic reader children. Methods. Two paradigms are tested: gap paradigm (fixation offset 200 ms prior to target onset), producing shorter latencies, in both non-dyslexic reader and dyslexic reader children and simultaneous paradigm. Seventeen dyslexic reader children (mean age: 1 2 ± 0 . 0 8 years) and thirteen non-dyslexic reader children (mean age: 1 2 ± 1 years) were tested. Horizontal eye movements from both eyes were recorded simultaneously by a photoelectric device (Oculometer, Dr. Bouis). Results. For all movements tested (saccades, vergence, isolated or combined) and for both paradigms, the mean velocity and accuracy were similar in dyslexic readers and non-dyslexic readers; no significant difference was found. Conclusion. This negative but important result, suggests no dysfunction of brainstem ocular motor circuits in dyslexic readers. It contrasts results on latencies related to visual attention dysfunction at cortical level.