Coloured lenses not supported by ophthalmologists for treating dyslexia

Dyslexia is a specific learning disability that is neurological in origin. It is characterised by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.

These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction.

Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and background knowledge.

These children who have dyslexia are at high risk of educational underachievement, explain consultant ophthalmologist Philip Griffiths and colleagues in an editorial.

An accumulation of evidence supports the view that dyslexia is a verbal (not visual) disorder, and shows that reading difficulties are best addressed by interventions that target underlying weaknesses in phonological language skills and letter knowledge.

Yet dyslexia is often associated with subjective experiences of visual distortions that lead to discomfort during reading (sometimes termed ‘visual stress’).

It has been argued that these symptoms can be alleviated through the use of coloured overlays and lenses – and that this can lead to an improvement in reading accuracy and fluency.

But a 2008 review of eight randomized controlled trials (RCTs) of coloured overlays and lenses concluded that the use of coloured filters “did not lead to a clear improvement in reading ability or symptoms of visual stress in subjects with reading disability.”

A more recent review also concluded that “the evidence base did not support the use of colour in the management of reading difficulty.”

Nevertheless, coloured overlays and lenses are used in classrooms and higher education institutions as a part of the remediation for reading difficulty, say the authors.

Both the International Dyslexia Association and Specific Learning Difficulties Australia websites provide links to academic websites that take a sceptical view of the existence of visual stress and treatment with overlays.

The advice issued by the professional bodies, whose members encounter children and adults with reading difficulties, does not support coloured overlays.

For example, 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 for the Royal College of Ophthalmologists concluded that “manipulation of the visual system using colour to facilitate reading lacks scientific support.”

Source: BMJ-British Medical Journal