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RESEARCH PRODUCT

Developmental dyslexia: Visual abnormalities during ocular rotation

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[u]Purpose[/u]: Most of the studies dealing with visual perception disabilities in children suffering from developmental dyslexia have been done in orthophoric position. The objective of the present study is to explore the visual perception during eye movements. [u]Methods[/u]: Sixty male patients (11.8 ± 1.8 years) were examined by neuropsychologists to evaluate reading difficulties. Visual perception during ocular rotation was assessed with a Clement Clarke synoptophore with G3–G4 slides, in primary gaze, then laterally at 20, 30 and 40° in dim light. [u]Results[/u]: Three main abnormalities were found. • Isolated perception abnormalities with intermittent shading of the image, central, paracentral or complete, • Phoria with permanent disappearance of the target edge, • Combined abnormalities (impaired perception and phoria). Isolated perception abnormalities were observed in 11% (7/60) and 60% ( 36/60) of the individuals in primary gaze and laterally (right or left) respectively. Phoria and combined abnormalities were seen in 30% (18/60) and 10% (6/60) of the cases respectively. Finally all the children displayed a visual perception defect during right and/or left rotation of the ocular globe. [u]Conclusions[/u]: These findings support a strong link between developmental dyslexia and impaired visual perception during ocular rotation. Their putative association with proprioception impairment remains to be determined.