Dyslexia possibly caused by treatable eye deformity

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In dyslexic people, both eyes have the same, round spot, which translates into neither eye being dominant, they found. During vision, the brain "knits together" the two images but grants priority to the dominant eye.

However, in a person who does not have dyslexia, these cells are arranged asymmetrically that helps the brain create a single image as the signals from one eye do not conflict with the other.

French scientists believe they have discovered a cause for dyslexia in the eyes of test subjects, and have developed a possible treatment using an LED lamp.

In a small study they found that most dyslexics had dominant round spots in both eyes - rather than in just one - leading to blurring and confusion.

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In non-dyslexic people, the cells are asymmetrical, according to the study published in the journal Proceedings of the Royal Society B.

Scientists compared it to being left- or right-handed; humans also have a dominant eye. But there is a tiny hole in the centre of the cornea where there are no blue cones.

This would result in the brain being confused by two slightly different images from the eyes.

Typically, the eyes of a person without dyslexia would have holes of uneven shape in each of their eyes.

"The lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities", the authors wrote. In the complex task of visually making sense of the world, the brain generates mirror images of what we see, as well as those the right way round.

"The existence of delays between the primary image and the mirror image in the opposite hemispheres [of the order of 10 milliseconds] has allowed us to develop a method to clear the mirror image that interferes with both the dyslexic", through the use of a kind of strobe light to the LED, said Mr Ropars.

Dyslexic people are known to make so-called "mirror errors" in reading, which is why they often confuse the letters "b" and "d".

He said: "For dyslexic students, their two eyes are equivalent and their brain has to successively rely on the two slightly different versions of a given visual scene".

Ophthalmologists will be able to diagnose the problem by looking into people's eyes and treatment may come in the form of special spectacles that cancel or block out the confusing signals.

In initial experiments, dyslexic study participants called it the "magic lamp", said Ropars, but further tests are required to confirm the technique really works.

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