Scientists have found dyslexics have an unusual pattern of cells in their eyes that makes letters difficult to read.
Studies of dyslexia have mainly focused on the brain but researchers discovered that sufferers had an unusual pattern of light-detecting cells.
Non-dyslexics have a circular arrangement of these cells, called cones, in one eye, which becomes dominant, and an oval pattern in the other, which creates a slightly less good image. During vision, the brain ‘knits together’ the two images but grants priority to the dominant eye.
In dyslexics, both eyes have a circular pattern of cones, which means each eye battles for dominance, causing confusion in the brain. This can lead to some letters such as ‘b’ and ‘d’ becoming confused. 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. It is not clear why this different pattern occurs in dyslexics.
Writing in a Royal Society Journal, the team from Rennes University in France say: ‘For dyslexic students, their brain has to successively rely on the two slightly different versions of a given visual scene, moreover often inducing poor and unstable fixation.’