The rate of dyslexia has been gradually increasing, in the U.S., without explanation. A reading disability can adversely affect self-esteem, have adverse social consequences, and cause the development of adaptive personality disorders. Some children with a reading disability excel in other areas and become successful adults; but the inability to read in early grades can also lead to bullying, failure in school, and the school-to-prison pipeline, as children act out to hide their inability to read, leading to suspensions, school drop-outs, and criminal behavior. Teachers believe vision is an important component of dyslexia; yet, scientific research has not confirmed their belief. We agree with teachers that vision is a significant component of dyslexia, and believe science should consider vision more broadly when a child has reading problems.
The vision and reading centers in the brain overlap, and use-it-or lose it applies. The ability to read requires binocularity (both eyes work together), without deviation in either eye; a fixed gaze (developed before age 7), which allows the eyes to maintain focus; and the ability to smoothly scan across a line on a page, and to start, stop and return to the beginning of the next line, without drift in either eye.
Babies are born with one eye turning in, which ordinarily corrects itself by the time the child attends school. When one eye does not develop proper alignment, it can lead to small losses in depth perception (and sensory perception), causing confusing signals to the brain as the child attempts to decode the written word. A child’s lack of binocularity or deviation in gaze may be too small to be noticed by an eye care professional, or too small to be thought in need of corrective action; yet, significant enough to impact reading. When a child has a significant discrepancy in refraction between eyes, it creates different image sizes in each eye, which can also confuse the brain when decoding the written word.
Tomorrow: Tools for helping children with reading problems.
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