The mystique surrounding the reason behind dyslexia has confounded doctors and scientists for ages.  Dyslexia is considered a language-based learning disability that results in people having difficulties with specific language skills such as pronouncing words and especially with reading and spelling words.  It affects an individual throughout their whole life making it a challenge for a person to succeed academically even though dyslexia is not due to either lack of intelligence or desire to learn – students who receive appropriate teaching methods can and due learn successfully.

It is estimated that as many as 700 million people worldwide or about one in ten of the global population have dyslexia leading to slow or inaccurate reading, poor spelling, poor writing, or mixing up similar words.  It is known that dyslexia does run in families as parents who have the condition are more likely to have children with it too.

The causes of dyslexia have never been completely understood but because of its connection to reading difficulties, the cause of the condition has often been blamed on the brain.

Recently, a pair of French scientists stated they may have found a physiological and perhaps even a treatable, cause for dyslexia and it appears not to have a connection with the brain.   This new study which is published in Proceedings of the Royal Society B, is linking the cause of this learning disability to tiny light-receptor cells in the human eye.

What the researchers found was a key physiological difference between the eyes of those with dyslexia and those without it.  The light-receptor cells are called rods and cones.  In people without dyslexia, the rods and cones are arranged in asymmetrical patterns in both eyes.   This allows signals from the one eye to be overridden by the other to create a single image in the brain without creating a “mirror” image when reading.  But in people with dyslexia, these cells are arranged in matching or symmetrical patterns in both eyes which appear to be the blame for confusing the brain by producing “mirror” images when they try to read. 

In this study, 60 people were divided evenly between those with dyslexia and those without it.  Discovered was that in the eyes of non-dyslexic people, the arrangement of the cones is asymmetrical with their dominant eye having a round, cone-free hole while the other eye has an unevenly shaped hole.  But in the people with dyslexia, both eyes have the same round hole. This lack of asymmetry could be the biological and anatomical basis making the ability to read and spell difficult. This means when they look at words in a book, their eyes perceive exact mirror images and appears to explain why it is almost impossible for them to distinguisha “b” from a “d” or an E” from a “3”. 

To be able to diagnosis dyslexia, the scientists state that all it takes is simply looking into a person’s eyes through an eye exam.  Even more exciting is that now that it looks like we are much closer to understanding the cause of dyslexia, the ability to treat it is also promising.  In the study, the authors used an LED lamp (nicknamed the “magic lamp”) that flashes faster than the human eye can perceive to “cancel out” one of the mirror images perceived by the dyslexic reader, leaving only one true image.  The scientists did state that more experiments will be needed to confirm if this technique really does work. 

In the meantime, it looks hopeful that in the future, dyslexia can be more easily diagnosed and treated.