Vision and Developmental Dyslexia

Dyslexia is a term that is used more widely in some areas of the country than others. Although there are different definitions of the term, which literally means “difficulty with words”, it represents one aspect of reading disability. Elsewhere on our website we discuss “vision and reading” in more general terms.

Dyslexia is generally used to refer to children who have the greatest difficulty in learning to read.

Unfortunately, many parents are led to believe that reading problems in general, and dyslexia in particular, have nothing to do with vision. A popular belief with educators, pediatricians, and eye surgeons is that reading disabilities are caused by “phonological problems”, or problems with phonemes — the sound of words, and that vision, at best, plays a limited role. If that sounds illogical to you, as a parent, it should.

One of the world’s foremost researchers in vision is John F. Stein, a Ph.D. in the Physiology Laboratory at Oxford University. Dr. Stein is the editor of volume 13 of the 17 volume encyclopledia, “Vision and Visual Dysfunction”. Volume 13 is entitled: “Vision and Visual Dyslexia”. This volume presents a detailed overview of what has come to be known as “the magnocellular theory” of dyslexia.

To make a very long story short, children labeled as having dyslexia typically lack the reading readiness skills to benefit fully from educational intervention. There are three popular methods of working with these children – Wilson, Lindamood-Bell, and Orton-Gillingham. Often these programs are slanted toward either a sight-word approach, or a phonetic approach. Any of these programs will help some of the children some of the time. But what if the child hasn’t developed adequate abilities to put the “grapheme”, or look of the word, together with the “phoneme”, or the sound of the word?

A research article by Shaywitz et al, in the journal Biological Psychiatry in 2002, hit the nail on the head with the title of its article: Disruption of Posterior Brain Systems for Reading in Children with Developmental Dyslexia. As it turns out, there are three main neural centers that light up in your brain during reading – and that can be imaged through functional neuroimaging (fMRI):

Occipitotemporal <->  Parietotemporal <-> Inferior Frontal Gyrus

Here’s the key phrase from their results: “Reading skill was positively correlated with the magnitude of activation in the left occipitotemporal region.” That’s the back of the brain where visual processing is online with information from the eyes.

So the secret to dyslexia is that the visual centers of the brain aren’t communicating well with the auditory/language and attention centers of the brain. It’s less important to debate whose responsibility it is to help these areas communicate with each other effectively, and more important to do something about it. And that’s where vision therapy is at its best, helping children integrate vision with movement, language, and attention. As reviewed elsewhere on this site, the research by optometrist, Dr. Harold Solan and his colleagues, pioneers in the application of magnocellular theory, helps explain why so many children who undergo vision therapy, experience improved reading abilities.