Research sheds light on dyslexia

French scientists may have found a physiological cause for dyslexia hidden in the rods and cones – photoreceptor cells – in the human eye. The learning difficulty affects one in 10 of the world’s population

Vision: Brain has to select one view of world using slightly different images from each eye

Dominance: Like being left- or right-handed, most people have one dominant eye – this eye sends priority visual information to brain

Iris

Pupil: Controls amount of light entering eye

Retina: Contains photoreceptor cells – rods and cones

Fovea: Area of clearest vision is rod-free, closely packed with cones

Sclera

Optic nerve

Choraid: Membrane packed with blood vessels to carry oxygen to retina Retina

Ora serrata

Iris

Pupil

Cornea: Protective covering

Lens

Rods: More sensitive than cones, but not sensitive to colour

Cones: Red, blue and green cones detect colour

Dominant eye: Blue cone-free spot at centre of fovea is round, but is unevenly shaped and
smaller in other eye

Dyslexic people: Both eyes have same round spot – brain cannot consistently select dominant image


Source: Proceedings of the Royal Society B (biology)
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