19th Oct 2017
A new study on the pattern of cells in the eye has shed light on the anatomical basis of dyslexia.
Scientists from the University of Rennes, France, studied the eyes of 60 people with normal vision – half of whom had dyslexia.
Dyslexia is a learning disability which affects up to 1 in 20 people in the UK, impairing reading, writing and spelling. Unlike other learning disabilities, it doesn’t appear to affect intelligence.
The results of the study suggest that people with dyslexia have dominant spots in both eyes, rather than just one.
Our eyes contain cells known as rods and cones, which are responsible for low-light and colour vision respectively. Cone cells come in green, red and blue forms, which respond to different wavelengths of light.
An area of the eye called the fovea has no blue-sensitive cone cells. In non-dyslexic people, the pattern of cells in each fovea is asymmetrical, making it easier for the brain to decide which eye to create an image from.
Lead author of the study, Albert Le Floch, describes how dyslexics had more symmetrical foveae – that is, neither was more dominant.
This makes it harder for the brain to decide which eye to form an image from, creating two versions of what we see.
The authors think this could be why dyslexics often struggle to read words easily, and experience “mirror errors” such as mistaking a ‘d’ for a ‘b’.
A new therapy using an LED lamp could trick the brain into ignoring one of the images, and has been reported by dyslexia patients to reduce their symptoms.
The full study, published in the journal Proceedings of the Royal Society B, can be found here.
