Dyslexia is a condition that is estimated to affect between 5-10% of the population, but this number may be as high as 17%. It is the most common cause of reading, writing, and spelling difficulties. Of people with reading difficulties, 70-80% are likely to have some form of dyslexia.
First documented officially in the late 1890s, the condition was considered a visual defect until the 1950s. Then, researchers moved to a more psychological explanation of the condition, pinpointing supposed information processing deficits in the brain as the cause. This led to dyslexics being stigmatized and considered “slower” than other children, with some in the early days even being institutionalized.
These days, a more nuanced and complex explanation of the condition and its possible causes has emerged. Dyslexia is currently characterized by physicians as “an unexpected difficulty in reading in an individual who has the intelligence to be a much better reader.” The modern understanding of the condition includes both a physical, vision-related component and a psychological, processing-related component, as well as some environmental and genetic factors. Research continues into causes of and treatments for dyslexia, and a recent study out of the United Kingdom conducted by the Royal Society came to a very interesting conclusion.
Human vision is binocular, relying on images received from both eyes to create a picture that includes information on distance and depth. Typically, people have one eye that is dominant while the other is non-dominant, giving the brain two different sets of information that are combined to create a full image. What the Royal Society researchers found is that eyes belonging to dyslexic persons had physically and functionally symmetrical eyes, meaning that neither eye was dominant. The team assessed eye dominance in 30 individuals with dyslexia and, in striking contrast to the non-dyslexic group, 27 had no eye dominance.
The current understanding of the psychological component of dyslexia involves individuals having weaknesses in brain lateralization, the ordering of brain functions between the right and left hemispheres of the brain. It is believed that most individuals develop normal, asymmetrical visual lateralization because each of their eyes perceives images slightly differently than the other, but need to be perceived as one, leading to one of the eyes being primarily relied upon for positional accuracy – the dominant eye. If indeed dyslexics possess symmetrical vision, that is no dominant or non-dominant eye, this could explain why they often have difficulty with brain lateralization. If this conclusion is borne out through repeated research, it could have an immense impact on how we understand, treat, and perhaps even one day prevent dyslexia.
Matossian Eye Associates1-800-708-8800 www.matossianeye.com
Melissa Mazzocchi, COA
Williams, R. (2017, October 18). Symmetrical Eyes Indicate Dyslexia | The Scientist Magazine®. Retrieved November 10, 2017, from http://mobile.the-scientist.com/article/50676/symmetrical-eyes-indicate-dyslexia/
Floch, A. L., & Ropars, G. (2017, October 25). Left–right asymmetry of the Maxwell spot centroids in adults without and with dyslexia. Retrieved November 10, 2017, from http://rspb.royalsocietypublishing.org/content/284/1865/20171380