Scientists say they may have found the cause of dyslexia in cells in the human eye, which could potentially be treated.
The study, from the University of Rennes, France, saw scientists look into the eyes of 30 non-dyslexics and 30 dyslexics.
Professor Guy Ropars, the study's co-author, told AFP: "Our observations lead us to believe that we indeed found a potential cause of dyslexia."
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The researchers found that with non-dyslexic participants, a particular spot in one eye was round but unevenly shaped in the other, with the round one more dominant.
With the dyslexic people, however, both eyes had the same round spot, and neither eye was dominant.
A dominant spot in one eye meant there were better connections between both sides of the brain - resulting in clearer vision.
People have a dominant eye in a similar way to a naturally dominant left or right hand.
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People with dyslexia have difficulties reading and writing, despite having normal intelligence, and can have problems distinguishing left from right.
Prof John Stein, a professor in neuroscience at the University of Oxford, described the research as 'really interesting' - because it highlighted the importance of eye dominance - but added that it found no indication of why the differences occurred in some people's eyes.
"No one problem is necessary to get dyslexia and no one problem is behind it," Prof Stein told the BBC.
Guy Ropars added that the lack of a dominant eye may 'be the biological and anatomical basis of reading and spelling disabilities'.
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."
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The team then used an LED lamp to 'cancel' one of the images in the brains of dyslexic participants while reading.
Ropars told AFP that dyslexic participants called it the 'magic lamp', but further tests are required to confirm the technique can help dyslexic people.
Dyslexia, which affects around 10 percent of people in the UK, often appears to run in families but environmental factors are also thought to contribute to the learning difficulty.
Initial signs of dyslexia usually become visible when a child begins to focus more on learning how to read and write, and can affect people of all abilities.
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Topics: Study, World News, France