Are UK dyslexia charities misleading parents and professionals about the benefits of colour lenses?An editorial in the prestigious British Medical Journal (BMJ 2014;349:g5160) has criticised six major UK dyslexia charities for ‘giving an inaccurate account of the evidence for the use of coloured lenses and overlays for managing reading difficulties’.
Authors Lisa M Henderson, Robert H Taylor, Professor Brendan Barrett and Philip G Griffiths, reviewed information on the use of overlays and tinted lenses provided by the websites of 11 dyslexia charities: eight in the UK and three in other English speaking countries. They found that six of the eight UK charities provided information about coloured overlays and lenses in dyslexia and that, ‘in all six cases the message was one of endorsement’. None of the six discussed the conflicting evidence base.
The three overseas charities fared much better. Dyslexia Ireland includes the use of overlays under its section on alternative or complementary therapies. The International Dyslexia Association and Specific Learning Difficulties Australia both provide links to academic websites that take a sceptical view of the existence of ‘visual stress’ (subjective experiences of visual distortions that lead to discomfort during reading) and treatment with overlays.
Professional bodies whose members encounter children and adults with reading difficulties are also sceptical. A recent joint statement from the American Academy for Pediatrics, Council for Children with Disabilities, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and the American Association of Certified Orthoptists concluded that, ’scientific evidence does not support the efficacy of…special tinted filters or lenses in improving long term educational performance.’
Similarly, a review prepared on behalf of the Royal College of Ophthalmologists concluded that, ‘manipulation of the visual system using colour to facilitate reading lacks scientific support.’
The BMJ editorial says that the consensus view among researchers is that dyslexia is a verbal not a visual disorder, which is best dealt with by interventions that target underlying weaknesses in phonological language skills and letter knowledge. It adds that while those with dyslexia may experience the symptoms associated with ‘visual stress’ these are not unique to dyslexia.
The authors acknowledge that the proponents of colour overlays or lenses do not claim that their use directly addresses the underlying cause of reading difficulties, but say they do argue that the reduction in visual distortion colour overlays or lenses bring about can improve reading accuracy and fluency. The problem, they say, is that, ‘the existing evidence base does not support this conclusion.’
Yet despite this, and the absence of any validated diagnostic tests for visual stress, ‘coloured overlays and lenses have become widespread in classrooms and higher education institutions as a core part of the remediation for reading difficulty.’ A number of factors may explain this but an important one ‘is endorsement from dyslexia charities’.
The editorial concludes, ‘Dyslexia charities have an important role in presenting constructive and helpful messages to people with dyslexia and their educators. Our observation does not detract from the positive role of these charities—advice on coloured overlays and lenses is only a small part of the information provided. However, an evidence based approach from UK dyslexia charities educated by good science would enable the public to make a more informed choice.’