Vision and Dyslexia
Written by Dr. Alisa Nola
When an adult or child has difficulty reading, a common concern is that they may have dyslexia. A child struggling in school may have trouble with reading fluency, poor reading comprehension, spend countless hours on homework, dread going to school, struggle to pay attention, or be smart but underachieving. Some adults may report that they never loved to read and always struggled in school.
Dyslexia has been generally understood as a difficulty with reading and spelling. The International Dyslexia Association defines dyslexia as a specific learning disability that is neurobiological in origin. It is characterized by difficulties with word recognition, poor spelling, and decoding abilities. These difficulties typically result from a deficit in the phonological component in language. Dyslexia is a language-based learning disability and is a life-long condition. It is suggested that there is a strong genetic link. As many as 15-20% of the population as a whole have some of the symptoms of dyslexia. Margaret Livingstone (Department of Neurobiology, Harvard Medical School) and the Dyslexia Research Laboratory (Beth Israel Hospital in Boston) define dyslexia as follows:
“Developmental dyslexia is the selective impairment of reading skills despite normal intelligence, sensory acuity, and instruction. Several perceptual studies have suggested that dyslexic subjects process visual information more slowly than normal subjects. Such visual abnormalities were reported to be found in more than 75% of the reading-disabled children tested.”
Research has found that 25% of school-aged children have a vison-related learning problem. That percentage increases to 80% when a child has other diagnoses such as dyslexia, ADHD, autism, developmental delays, and learning problems. There is a high prevalence of visual abnormalities in those with dyslexia. Vision plays a very important role in learning and reading. 80% of learning is through the visual system.
There are two major areas in vision that affect learning: visual efficiency (the mechanics) and visual processing (how the brain utilizes visual information). Visual efficiency skills include oculomotor (eye tracking), binocular (eye teaming), and accommodation (eye focusing). Common visual efficiency signs and symptoms include blurry vision, words swimming on a page, double vision, headaches, words going “in” and “out” of focus, losing place while reading, eyestrain, or omitting small words while reading. Visual processing skills include identification and discrimination, visual spatial (laterality and directionality), processing speed, visual-motor integration, visual analysis (form constancy, discrimination, figure ground, and visual closure), visual memory, and integration with other senses. Signs and symptoms of visual processing difficulties may entail confusing similar words (home/house), reversing numbers (6 and 9) or letters (b and d), reversing words (was/saw), transposing letters or numbers (12/21), confusing “Right” and “Left”, poor spelling ability, and difficulty recalling what was read.
A common misconception is that dyslexia causes transposals and letter reversals. Letter and number reversals are actually an indication of a visual spatial (laterality and directionality) deficiency and visual processing difficulty. If a person has difficulty with laterality (knowing their own “Right” and “Left”), this may predispose them to difficulty with recognizing directions in relation to letters (b and d) or numbers (6 and 9). In addition, because poor saccades (tracking while reading) results in inaccurate eye movements, this can cause someone to read words or letters out of order. A common symptom is that words appear to be “jumbled”. Instead of reading and learning being an enjoyable way to gain knowledge, it may now be associated as a difficult and challenging task.
Reading requires adequate visual and language skills. Learning to read consists of two sets of brain regions: the object recognition (visual system) and the language circuit. The visual system recognizes the shapes of letters and connects them to speech sounds. If there are any visual signs or symptoms, or difficulty with reading and learning, visual dysfunctions should be ruled out by a developmental optometrist. As stated above, there is a high prevalence of vision-related problems in those diagnosed with dyslexia. Vision therapy involves guided and individualized treatment of deficient visual mechanics and visual processing skills. Although vision therapy does not directly treat dyslexia, vision therapy can treat the visual dysfunctions that often worsens symptoms for an individual with dyslexia.
“Better vision and better learning promises better living”