Do Vision Problems Cause Dyslexia?

One of the perennial questions we get asked: What causes dyslexia?  Current research has shown definitively that dyslexia is neurobiological in origin as a difference in the way the reading systems in the brain are structured to handle a written language task.  Functional MRI’s show the difference in processing between an average reader and a dyslexic reader (see above image).

And yet, we still hear sometimes from those that link vision problems to dyslexia. Can poor eyesight affect reading?  Yes, but generally once the problem is corrected with glasses or contacts, skills quickly pick up.  What about Visual Convergence issues?  A visual convergence issue will impact the ability of the eyes to turn toward each other.  Some pediatric ophthalmologists will diagnose this in children who have difficulty tracking lines of print, skipping words, or chunking together wrong words.  However, these issues also match students who have characteristics of ADHD and/or dyslexia.  Also, it is more common for a true convergence issue to present in older high-school students or adults, rather than elementary-aged children when it is frequently diagnosed as a cause for reading issues. 

In the end, reading issues should be diagnosed by a reading professional such as a dyslexia therapist, clinical psychologist, or neuropsychologist. Intervention should be language-based and involve systematic instruction in the “code” behind the language process that makes up our reading/spelling systems in the brain.

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