Perceptual evidence for an anomalous distribution of rods and cones in the retinas of dyslexics: a new hypothesis.

The present study tested the hypothesis that from the ability of dyslexics to read peripheral letters one may infer the presence of cones, those visual receptors specialized for acuity, in the peripheral retina. The cones are also the receptors for color discriminations. The method of retinal perimetry was used to map color-sensitive zones of the retina for 14 dyslexic and 14 control subjects. A statistically significant difference showed that the 14 dyslexics reported colors at more peripheral positions than did the 14 normal readers. These data are consistent with the premise that dyslexics have an anomalous distribution of retinal receptors. These findings perhaps may help to explain the erratic eye movements of some dyslexics. It is suggested that retinal perimetry might be one component of a diagnostic battery for the differential diagnosis of dyslexics.