At Vision Through Colour we assess for Visual Stress not dyslexia; colour, when it is helpful, helps by relieving Visual Stress symptoms, not by managing or treating dyslexia. Any benefit of colour only comes from help with pattern, text and light sensitivity, not from managing the core features of dyslexia, which are phonological.
It’s really important to remember that dyslexia and Visual Stress are two distinct and different conditions. The most recent Delphi definition of dyslexia [Carroll et al., 2025] doesn’t include visual difficulties, highlighting that although “phonological difficulties do not fully explain the variability that is observed” from individual to individual, difficulty in phonological processing is “the most commonly observed cognitive impairment”.
We have heard some people hold the view that Visual Stress occurs in most people with dyslexia and others say that it doesn’t occur in dyslexia at all – our belief, from our clinical experience, and from our understanding of the research, is that Visual Stress can impact people with dyslexia, but only in some.
When we are assessing the difficulties any individual is having with reading, we are also careful to consider and exclude other possible visual causes for the difficulties – from eye disease and refractive error (the need for glasses to see clearly) through to convergence or accommodation difficulties (problems with the focussing of the eyes) and binocular vision difficulties, including binocular instability (difficulties with eye co-ordination).
We also think it is important to consider visual function more broadly than just measuring reading speed and so also consider comfort and ease of reading, which may not be reflected in speed. Our symptom checker tool can be helpful to give a feel for any difficulties with visual discomfort that an individual may experience in broader everyday life.
The College of Optometrists advocates a cautious approach to the use of colour in specific learning difficulties; their guidelines referencing the need for more evidence and highlighting the different conclusions from two opposing reviews of the literature that was available in 2016.
In a 2016 literature review, “The effect of coloured overlays and lenses on reading: a systematic review of the literature.” (Griffiths, Taylor, Henderson et al), the authors review the literature about reading performance, stating the purpose of their review as follows,
“There are many anecdotal claims and research reports that coloured lenses and overlays improve reading performance. Here we present the results of a systematic review of this literature and examine the quality of the evidence.”
They conclude,
“Consistent with previous reviews and advice from several professional bodies, we conclude that the use of coloured lenses or overlays to ameliorate reading difficulties cannot be endorsed and that any benefits reported by individuals in clinical settings are likely to be the result of placebo, practice or Hawthorne effects.”
On the other hand, a literature review by Evans and Allen in the same year, “A systematic review of controlled trials on visual stress using Intuitive Overlays or the Intuitive Colorimeter”, makes the distinction between dyslexia and visual stress. And conclude,
“This review indicates that visual stress is distinct from, although sometimes co-occurs with, dyslexia. Individually prescribed coloured filters have been shown to improve reading performance in people with visual stress, but are unlikely to influence the phonological and memory deficits associated with dyslexia and therefore are not a treatment for dyslexia.”
It is worth considering, as Evans and Allen do, that how people are selected for research when assessing the evidence for the use of colour in visual stress is important,
“It is clear from the literature that most people with dyslexia do not have VS and therefore studies investigating the effect of coloured filters on samples selected as having dyslexia suffer from selection bias and will be underpowered. It is perhaps surprising that not all studies of VS have studied people with VS and reviews that fail to make the differentiation between dyslexia and VS are likely to reach invalid conclusions.”
Not everyone will benefit from colour, so it is important to approach things carefully on an individual, case by case, basis as part of a thorough assessment. At Vision Through Colour, we are careful to ensure that each individual considering colour appreciates any benefit of colour for themselves, from their personal experience, especially before proceeding with precision tinted glasses.
