DYSLEXIA - THE LINK WITH VISUAL DEFICITS

Some research reports suggest that visual anomalies may have a causati ve role in dyslexia, and on this basis certain forms of therapy have b een proposed. Recently, we have published the initial results of a mat ched group study which found dyslexia to be associated with binocular instability, reduced amplitude of accommodation, and reduced contrast sensitivity for both low spatial frequencies and uniform field flicker . The binocular instability was best identified by measuring the verge nce amplitude: a modified Dunlop test failed to differentiate reliably between the two groups. Here, we report a significant correlation bet ween flicker threshold and binocular instability, thus linking sensory and motor visual correlates of dyslexia. We also present further new analyses on the interaction between optometric variables and the psych ometric measurement of coding skills. The results of these analyses di sagree with a recent claim that binocular vision anomalies might cause poor performance at coding tasks. Our studies indicate that visual ch aracteristics are not the major aetiological factors in specific readi ng difficulty.