Coloured overlays, bad science, and the B B C (The Windscreen Analogy).

Last week the BBC reported on a study by researchers from Bristol and Newcastle which cast doubt on the efficacy of using coloured overlays to help with reading difficulties. Now that the storm  has died down a bit, I thought it’s time I put in my penn’th (is that how you spell it?).

“Dyslexia not linked to eyesight”, trumpets Sean Coughlan of the BBC. Absolutely right. But who said it was? Therefore coloured overlays don’t work for dyslexia, infer the researchers. Indeed they don’t. However, what they do work for is visual stress, which happens to be a condition of the visual cortex that quite a lot of dyslexic people suffer from, but which has no direct connection with any of the ophthalmic data that the researchers analysed.

Basically there are four separate threads here: Dyslexia, the eyes, coloured overlays, and visual stress (linked with the visual cortex). Because (despite the efforts of Bruce Evans, Arnold Wilkins and other academics), confusion and ignorance still generally prevail over the relationship between dyslexia and visual stress, the researchers have looked at their data on eye conditions (short-sightedness, convergence problems etc) and responded to questions from concerned parents with the following logic:

“We find no statistical correlation between dyslexia and eye problems, therefore a coloured filter can’t make any difference to how words appear to the reader” .

I was trying to think of something that would illustrate the failings of this logic, and decided it was a bit like saying “The demister in your car doesn’t affect the rain on the windscreen, so you’re wasting your time using it on the condensation.”

If you don’t make sure your car windscreen is free of condensation, you run the risk of crashing your car. Sadly, some parents will have listened to the bad science promulgated by the BBC, and run the risk of crashing their child’s reading as a result. And the BBC will be responsible for the crash. You can phonic a child to death, but they will never read with ease and comfort until the words stop moving around – and in many cases the only way to achieve that is by reading through colour, because nothing else deals with the hyper-excitation of the visual cortex that causes visual stress.

Incidentally the Daily Mail, who picked up on this story as well, ran an article on our reading rulers a few years ago entitled “Now you can read through colour”. Obviously it made a good story at the time – 2008, I think it was. Now, in 2015, it makes a good story to say the opposite. Hello? Is anyone out there interested in the truth?

Bob Hext, 5th June 2015.

Can the Hand say to the Eye: “I have no need of thee?”

Edward Jenner

Edward Jenner (Photo credit: Wikipedia) would have had the same problems…

In the original quote, (from 1 Corinthians 12: 21, in the New Testament of the Bible) the eye and the hand were the other way round, but never mind…

While I was researching an article I wrote for Special Magazine in March, I came across the following…

‘A policy statement issued by the Committee on Children with Disabilities, American Academy of Paediatrics, American Academy of Ophthalmology, and American Association for Paediatric Ophthalmology and Strabismus stats that:

“Visual problems are rarely responsible for learning difficulties. No scientific evidence exists for the efficacy of eye exercises, vision therapy, or the use of special tinted lenses in the remediation of these complex neurological conditions.” ‘

Having got over my sense of frustration at this attitude, I had to ask myself the questions: “Just what, or whose, agenda are these people on?” and “Exactly where have they been looking for evidence?”, and even “Have they seen just how much of the brain is dedicated  to visual processing?” . I’ve been meaning to post on the subject ever since.

Unless this committee’s view of learning is limited to specific cognitive processes that take place entirely outside of the visual processing centres (and of course they understand  the brain in its entirety, unlike the rest of  the human race to whom it is currently given, I believe, to understand less than 10%…), this seems like saying “If a car doesn’t work properly it’s never got anything to do with the transmission”.

What’s worrying is that committees such as this one make pronouncements that influence policy, and that simple, cost-effective interventions that will both change lives and save large amounts of money remain sidelined instead of becoming enshrined in mainstream thinking. Nobody would deny the need for evidence-based research to underpin policy, but even if the sheer weight of anecdotal evidence of many thousands of people for whom the “words stopped moving” as soon as they read through colour is insufficient, is the scientific rigour and the peer-reviewed research of the Dept of Vision Science at Essex University not enough?

I suppose it’s always going to be that way: Science waits in the car with the engine running, while the establishment is still asleep in bed. Edward Jenner would have had the same problems introducing his discovery of the smallpox vaccine, and the science of immunology…  But if anybody has any means of contacting the above committee, would they mind sending them a copy of this link to Arnold Wilkins’s web pages, “Colour in the Treatment of Visual Stress”   and ask them to PLEASE WAKE UP?

Bob Hext   June 2013.

Visual Stress and Dyslexia

There’s still a lot of confusion around on the subject of Visual Stress and its relationship to Dyslexia so I’m going to post a series on the topic to try and clear some of it up.

They’re not the same thing
That’s the first point. Dyslexia is a cognitive processing difficulty; Visual Stress is a disorder of the visual processing system. Visual Stress is common in dyslexia, but does not cause it. In fact about 35% of dyslexics suffer from Visual Stress. It is also fairly common (though less so) in other specific learning difficulties, especially dyspraxia, ADD/HD and autistic spectrum disorders – the autistic author Donna Williams, for example, is well-known for her pink tinted lenses. It actually occurs in about 25% of the population, so it is more common than dyslexia (usually quoted at around 10%); and severely – to the extent that literacy is significantly impaired- in about 5%.

What are the symptoms?
For those who don’t know exactly what I’m talking about here, Visual Stress is a condition that causes headaches and sore eyes, skipping words or lines, hesitant reading with many errors and poor comprehension, and  perceptual distortions  including movement of letters and words on the page, flickering shadows and coloured  “halos”,  and “rivers” of white running down it. Visual Stress itself is thought to be caused by specific wavelengths of light (they differ with each individual, although certain parts of the spectrum cause more problems than others) that over-stimulate cells in the Visual Cortex, and its effects can be reduced or eliminated by simply placing a precision coloured filter over the page or by wearing precision tinted lenses.

Coloured Overlays don’t cure dyslexia
Websites which claim that overlays “cure dyslexia” are not helpful in this respect. As mentioned above it’s Visual Stress that we’re talking about, not dyslexia; and secondly they don’t “cure” Visual Stress any more than spectacles cure short-sightedness: they just deal with the symptoms. Over-simplified claims that are made for marketing purposes and have no basis in science just add confusion to the subject.

“Visual Dyslexia”
This is a term favoured in some circles and is used by some behavioural optometrists. Behavioural Optometry has a valuable contribution to make to Vision Science, but  is muddying the patch with this terminology which is possibly promoted by  certain individuals to distance themselves from scientists who query their claims. There is an ancient saying “The Unity commands the blessing”. Factions don’t ultimately help any causes.  Enough said.

Call a spade a spade
We all know what a common cold is, and we know what treatments are available – although the jury may be out on whether they actually work! It’s the same with Visual Stress. As well as “Visual Dyslexia”, it’s also called “Irlen Syndrome ®”  (the registered trade mark of the Irlen Corporation), “Meares-Irlen” and “Scotopic Sensitivity”, which was the term originally used to describe the condition by Helen Irlen when she first started marketing coloured overlays and tinted lenses in the 1980’s.  “Scotopic Sensitivity” is in fact a scientifically inaccurate term, as it refers erroneously to the spectral response of the rod system in the retina. Visual Stress is actually a neurological condition of the visual cortex. If we don’t even agree on what it is called, how are we ever going to understand and treat it?

Different Explanations
There are two differing theories as to the causes of Visual Stress. The one mentioned above is called “Cortical Excitablity” and is proposed by Professor Arnold Wilkins of Essex University. There is another theory called “Magnocellular Deficit”, which suggests that the problem is caused by a weakness in the transient (Magno) processing cells in the Visual Cortex. This is the theory put forward by Professor John Stein of Oxford University who heads up the Dyslexia Research Trust. Both these academics are eminent scientists doing valuable work and bringing great benefit to the community. The weight of evidence would appear to be in favour of the Essex research, but the fact  that scientists disagree on the “Why” doesn’t encourage public acceptance of the “What”.

It’s not Always Visual Stress!
The symptoms mentioned above can be caused by other problems in the visual system, and so coloured overlays are not always the answer – although often they are! Binocular Instability is quite common (though less so), and there can also be accommodative  anomalies (problems with focus). Where reading difficulties persist it’s always important to refer to an Optometrist. A list of those who specialise in Visual Stress can be found at

Visual Stress is a reality
So whatever we call it today, and whatever its cause, the existence of Visual Stress and the validity of precision tinted filters to treat it is a reality. And it isn’t the same as Dyslexia: if coloured overlays effectively treat the Visual Stressexperienced by a dyslexic person, the other processing difficulties associated with that person’s dyslexia will remain. I will post on some of the research that proves the reality another day: today let’s all call it the same thing and get on with taking it seriously.