Dyslexia would have anatomical causes

Two French researchers have discovered an abnormality in the eyes of people with dyslexia, work that has generated a lot of interest in recent months. This anomaly is located at the fovea level and could explain why dyslexics have difficulty reading and writing.

A text by  Daniel Carrière  Discovery

Dyslexia is a disorder of learning written language that would affect more than 700 million people. It is a mysterious evil and its causes are the subject of much debate. Despite a normally functioning brain, dyslexics would have trouble decoding certain letters.

When he reads, Edwin Cotar, one of the young French students who took part in the study, sees mirror images. He stumbles on some letters; the b for example turns into d and the p becomes a q.

With all these letters constantly dancing in their heads, dyslexic people have difficulty reading and many of them completely give up reading at a young age. The sources of dyslexia are not known, but research published to date indicates that neurological and genetic causes are behind this disorder.

New hypothesis

The physicists Albert Le Floch and Guy Ropars, attached to the University of Rennes, have issued a new hypothesis: there would be an anatomical difference in the eyes of dyslexic people. This anomaly is located in the center of the fovea, in a tiny area that is less than a millimeter in diameter and is called the Maxwell spot.

By studying Maxwell's task of 30 dyslexic and non-dyslexic students, the researchers found that this small structure was different from one group to another. The spots were asymmetrical in non-dyslexic and perfectly round in dyslexics.

According to them, the round spots are attached to the function of the dominant eye. By having perfectly rounded Maxwell spots in each eye, dyslexics would have two dominant eyes, which creates an overload of information in the visual cortex and produces "mirror images".

"For standard people who do not have a dyslexia problem, this image [le d] will be hidden. We will not see it. So, we will only see b. On the other hand, if it is too symmetrical, as in the case of a dyslexic person, you will see both b and d. So the problem, [is that the brain] can not choose in these cases, so we have two images that have about the same intensity, "says Guy Ropars.

The "magic" lamp

Not only do researchers think they have discovered one of the mechanisms of dyslexia, but they have also developed a technique to turn off mirror images that create confusion when reading. It is a strobe light that emits flashes of light at different frequencies. The young dyslexics who participated in the study call this strobe light the "magic lamp". It would fix the letters and make the silent reading more fluid.

"It seems clearer to me. I am less confused. It's true that there are no more lines. The line that I read comes out better than it does now. I am less confused, "says Edwin Cotar, during a reading session using the strobe light.

Disputed hypothesis

However, learning disorders specialists are not convinced by the conclusions of these researchers. Dave Ellemberg, a neuropsychologist who studies the development of visual functions at the Université de Montréal, points out that it is far too early to draw conclusions and that the study does not specifically mention how the level of reading of dyslexic people is improved with the strobe light.

Guy Ropars and Albert Le Floch are not experts in dyslexia, they are physicists specializing in the study of vision and lasers. Their research on the symmetry of Maxwell's spots of dyslexic people was published in the British scientific journal Proceedings of the Royal Society .

This research was immediately criticized by specialists in learning disorders. The French Federation of Dyslexia is very cautious. It states that the methods used by researchers are unconventional and that it is difficult to appreciate their full value.

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Dyslexia would have anatomical causes