Dyslexia is primarily a language-based reading disability, not a visual-based disability.
Research has shown that people with dyslexia are more likely to have children with dyslexia. A child with one parent with dyslexia is about 40% to 60% likely to have dyslexia themselves.
In dyslexia identification there are clear and well-defined cut-off points. An individual either has dyslexia or not.
Because the core difficulties associated with dyslexia are related to how the individual sounds of language are processed in the brain, and not visual perception, coloured overlays do not improve reading accuracy or comprehension for dyslexic students. Research evidence shows no significant benefit in terms of objectively measurable reading gains when using colored overlays despite the fact that many dyslexic students report that they find them useful.
People with dyslexia have difficulties with processing and manipulating the smallest sounds of language, called phonemes. Research shows that, in students with dyslexia, the part of the brain that processes those sounds and connects those sounds to letters is under-activated as compared with typically developing readers. People with dyslexia also perform more poorly on tasks that require analyzing, synthesizing, and manipulating phonemes.
There is no scientific evidence that seeing letters and words backwards is a characteristic of dyslexia.
There is a significant and pronounced difference between males and females when it comes to ‘identified’ dyslexia and reading difficulties. There are a number of reasons for this, one of them is that females and males use different behavioural and emotional compensation techniques and react differently when faced with these challenges. Therefore boys are more easily identified as dyslexic in school settings. When researchers identify dyslexia in the general population, there is less pronounced difference between males and females in the prevalence of dyslexia. Researchers examined gender differences based on the variation in reading abilities among males and females. They found that males show more variability and depending on the cut-off point for identifying dyslexia, indeed there might be more male than female dyslexics (Hawke, J. L., Olson, R. K., Willcut, E. G., Wadsworth, S. J., & DeFries, J. C. (2009). Gender ratios for reading difficulties. Dyslexia, 15(3), 239-242.)
This statement might be true although research evidence is often contradictory on this question.
Research suggests that there are significantly more dyslexic individuals among art students than non-dyslexic ones (Wolff, U., & Lundberg, I. (2002). The prevalence of dyslexia among art students. Dyslexia, 8(1), 34-42). There is also neuroimaging evidence that shows that lower reading skill is associated with a visuospatial processing advantage (Diehl, J. J., Frost, S. J., Sherman, G., Mencl, W. E., Kurian, A., Molfese, P., … & Pugh, K. R. (2014). Neural correlates of language and non-language visuospatial processing in adolescents with reading disability. NeuroImage, 101, 653-666). However, some studies have found that the visuospatial superiority is more apparent in dyslexic men than women (Brunswick, N., Martin, G. N., & Marzano, L. (2010). Visuospatial superiority in developmental dyslexia: Myth or reality?. Learning and Individual Differences, 20(5), 421-426.)
Because dyslexia is caused by difficulties with processing individual sounds of language in the brain, researchers know that effective instruction includes explicit and systematic instruction in phonemic awareness (practice manipulating the individual sounds in our language) and phonics (practice connecting those individual sounds, or phonemes, to letters). There are no scientifically proven benefits of eye-tracking exercises.