DIFFERENCES IN EYE-MOVEMENTS AND READING PROBLEMS IN DYSLEXIC AND NORMAL-CHILDREN

It has been suggested that eye movement abnormalities seen in dyslexic s are attributable to their language problems. In order to investigate this claim, we studied eye movements in dyslexic children, during sev eral non-reading tasks. Dyslexic children were compared to normal and backward readers on measures of fixation, vergence amplitude, saccade and smooth pursuit. The results were compared to the children's phonol ogical ability. Dyslexic children (n = 26) had significantly worse eye movement stability during fixation of small targets than normal child ren (n = 39). Vergence amplitudes were lower for dyslexics than for co ntrols. A qualitative assessment of saccadic eye movements revealed th at dyslexics exhibit fixation instability at the end of saccades. Asse ssment of smooth pursuit revealed poor smooth pursuit in the dyslexic group, particularly when pursuing a target moving from left to right. Dyslexic children also performed significantly worse than normal child ren on a test of phonological awareness (Pig Latin). Eye movement resu lts were studied in the light of the findings on phonological awarenes s: dyslexics with small vergence amplitudes also always have poor phon emic awareness. However, poor fixation control is found in dyslexics w ith or without poor phonological ability. The backward reading childre n performed similar to the dyslexics on all tests, suggesting that the deficiencies observed in this study are not specific to children with dyslexia. The problems experienced by the children (revealed by a que stionnaire) are in agreement with those measured in terms of eye movem ent recordings and phonemic awareness. Sex, handedness, IQ or the pres ence of attention deficit disorder (ADD) did not appear to influence t he children's performances on any of the eye movement tasks. The prese nce of oculomotor abnormalities in a non-reading task strongly suggest s that the underlying deficit in the control of eye movements seen in dyslexics is not caused by language problems alone.