UK experts said the research was "very exciting" and highlighted the link between vision and dyslexia.
But they said not all dyslexics were likely to have the same problem.
People with dyslexia have difficulties learning to read, spell or write despite normal intelligence.
Often letters appear to move around and get in the wrong order and dyslexic people can have problems distinguishing left from right.
Human beings have a dominant eye in the same way that people have a dominant left or right hand.
Shape of spots
In the University of Rennes study, published in the journal Proceedings of the Royal Society B, scientists looked into the eyes of 30 non-dyslexics and 30 dyslexics.
They discovered differences in the shape of spots deep in the eye where red, green and blue cones - responsible for colour - are located.