Monocular occlusion can improve binocular control and reading in dyslexics

Developmental dyslexia is a neurodevelopmental condition which causes 5-10% of children to have unexpected difficulty learning to read. Many dyslexics have impaired development of the magnocellular component of the visual sys tem, which is important for timing visual events and controlling eye moveme nts. Poor control of eye movement may lead to unstable binocular fixation, and hence unsteady vision; this could explain why many dyslexics report tha t letters appear to move around, causing visual confusion. Previous researc h has suggested that such binocular confusion can be permanently alleviated by temporarily occluding one eye, The aim of the present study Mras theref ore to assess the binocular control and reading progress of dyslexic childr en with initially unstable binocular control after the left eye was patched . One hundred and forty-three dyslexics were studied. They were selected Fr om children aged 7-11 years referred to a learning disabilities clinic if t hey were dyslexic and had unstable binocular control. They were randomly as signed to wear yellow spectacles with or without the left lens occluded, an d mere followed for 9 months, Significantly more of the children who were g iven occlusion gained stable binocular fixation in the first 3 months (59 % ) compared with children given the unoccluded glasses (36 %), This advantag e was independent of IQ or initial reading ability. Furthermore, at all the 3-month followups, children were more likely to have gained stable binocul ar control if they had been wearing the occluded glasses. Gaining stable bi nocular control significantly improved reading. The children who did so wit h the help of occlusion improved their reading by 9.4 months in the first 3 months, compared with 3.9 months in those who were not patched and did not gain stable fixation, Over the whole 9 months, children who received occlu sion and gained stable fixation nearly doubled their rate of progress in re ading compared with those who remained unstable, At all the follow-ups the reading of those given occlusion was significantly better than that of thos e not occluded, Thus monocular occlusion helped children with unstable bino cular control to gain good binocular fixation, If they gained stability, th ey made significantly faster reading progress. The progress made by the chi ldren who gained stable fixation was much greater than that achieved with o ther remedial techniques.