In a school in the South of England, a teacher hands out the lesson's worksheets to her class. Rather than just distributing a stack of white papers, she also holds a rainbow of coloured overlays. For this teacher believes that the reading ability of certain students can be greatly improved by changing the colour of the text or background to match the colour preference of their vision.
This may prompt an incredulous smirk from some of those reading - a demonstration of why the teacher above wishes to remain anonymous. Despite being mooted by scientists and academics for about 30 years and finding acceptance among some dyslexia and reading experts - as well as many teachers - the use of coloured overlays remains very much on the peripheries of mainstream acceptance. This is partly out of ignorance, partly because of cost, but also because some simply do not believe the science behind it.
The hypothesis is that, in some people, certain frequencies of light can cause a hyperexcitabilty of the visual cortex, a condition called visual stress. According to Arnold Wilkins, professor of psychology at the University of Essex, who has conducted much of the research in this area, this results in "perceptual distortion (mainly of text or other spatially repetitive material) and associated discomfort".
Those suffering with visual stress can experience movement of print; blurring of print; letters changing shape or size; letters fading or becoming darker; patterns appearing; illusions of colour (blobs of colour on the page or colours surrounding letters or words); rapid tiring; headache; and eyestrain.
The theory is that overlays of a colour matched to each individual's requirements can limit or even remove these perception difficulties by redistributing and reducing the hyperexcitability.
While some are convinced that a condition along the lines of visual stress exists, many view the use of coloured overlays to treat it with suspicion. Research from Esther Albon et al at the University of Birmingham in 2008 (bit.lyColouredFilters) states that there is "no convincing evidence to suggest that coloured filters can successfully improve reading ability in subjects with reading disability or dyslexia when compared to placebo, or other types of control".
Furthermore, in 2011 the American Academy of Pediatrics, looking at one type of overlay only, said that "coloured overlays do not have any demonstrable immediate effect on reading in children with reading difficulties". And a joint statement in 2009 from the American Academy of Pediatrics Section on Ophthalmology, the Council on Children with Disabilities, the American Academy of Ophthalmology, the American Association for Pediatric Ophthalmology and Strabismus, and the American Association of Certified Orthoptists questioned the evidence of the effectiveness of tinted overlays, stating that "special tinted filters or lenses are not endorsed and should not be recommended".
With such opposition to the idea, no wonder teachers can be uninterested or downright incredulous. And yet, despite this evidence, many teachers do still use the overlays and claim a beneficial impact, while the British Dyslexia Association advocates the use of coloured overlays for the 35-40 per cent of dyslexic children it says encounter "visual disturbance" (another term for visual stress). Many special educational needs (SEN) professionals support their use, too, and not just for dyslexic children.
Daniel Sobel, an SEN expert in the UK, says that the lack of take-up of coloured overlays is one of many areas where schools are failing SEN students. Meanwhile, Garry Freeman, director of inclusion and special educational needs coordinator at Guiseley School in Leeds, says: "I've supported the use of overlays for several years for any child who reported that for them letters and words moved around a page. It's a very small expense to support a child."
Wilkins says that this support is there because research has proved the efficacy of the intervention. "In a study we conducted in 2001, of 400 schoolchildren aged between 7 and 8, in 12 schools in Norfolk, England, 5 per cent increased their reading speed by more than 25 per cent using an overlay selected on the basis of comfort and clarity from 10 options," he says.
This study and others are cited with references in his paper "Visual stress and its treatment" (bit.lyVisualStressTreatment). The International Institute of Colorimetry also has a list of research papers supporting the use of coloured overlays (www.colorimetryinstitute.orgresearch-papers).
So while coloured filters are not universally accepted, the debate is more nuanced than it may at first appear. Visual stress, and the use of coloured overlays to fix it, has some heavyweight opponents, but the counter arguments - and the supporters of those arguments - are out there. Teachers need to assess both sides of the debate but, as Freeman says, it is not actually up to them to make a diagnosis, just to be open to the idea: "When a child shows symptoms, I always contact parents and strongly advise that they have their child's vision checked and referred to a specialist if necessary."
Chapter and verse on Irlen syndrome and how to help your students cope with visual stress.bit.lyVisualDyslexia
The use of coloured overlays to assist with reading is not a new idea, but it is a contested one.
While advocates claim beneficial results from using bespoke coloured overlays with students who report issues such as moving text or blobs of colour appearing on the page, opponents say the positive impact cannot be proved.
Despite this, many SEN specialists and groups such as the British Dyslexia Association still advocate the use of coloured overlays.