Background information and research

Some NHS trusts have written their own guidance on Visual Stress so that they can include specific hospital departments to be referred to.     Traditionally Dyslexia and Visual Stress was seen as an area dealt with by educational professionals, who then referred to GPs.     However, some Orthoptic Departments in hospitals now test for Visual Stress as well, as part of the seamless linking of services for children with disability needs.   The following have good online guidance.      

We provide and create resources to help with reading and writing both in the educational environment and the workplace.    We have a comprehensive list of products that help with visual stress on paper:  tinted exercise books, pads and paper, and overlay products,  mostly available in the range of ten colours suggested by research. For visual stress on the computer we have our  Tint and Track software. We have developed pencil grips and our own extra-wide writing slope to help with writing, and stock a wide range of games, workbooks and activity packs to support the teaching of literacy to children, particularly those with specific learning difficulties.   Our latest development has been a dyslexia friendly font, called Aravis.   

Our overlays and reading rulers were developed according to the research done by Prof Bruce Evans, of the Institute of Ophthalmic Opticians, and Prof Arnold Wilkins of Essex University.     Their research is now supported by many other peer reviewed papers.   (See links for details of bio and research) Arnold Wilkins now has 183 peer reviewed papers on his site at Essex University and has received several prestigious awards for his work on defining Visual Stress and pattern glare.

We follow Arnold’s research to determine the correct amount of colours to cover the spectrum of hues at a defined depth and saturation.  This includes colours that are not often used but are needed to ensure that no student is missed when testing is carried out.   

All our reading rulers and overlays are made using eco-friendly PET.    This is one of the most ultra clear plastics available and it provides a smoother substrate for colour printing than commonly used PVC.    Cerium, another supplier of overlays and the manufacturers of the “Intuitive Colorimeter” used by optometrists,  use an acrylic substrate which is also very clear.     Most of the overlays on Amazon as we write are PVC, which has less clarity, a slight yellow tint and an uneven surface making it impossible to guarantee the end colour batch on batch. 

Our first small production runs of visual stress products back in 2004-6 were quite variable in different batches because of the printing process that we used at the time.    However as the popularity of the overlays grew we were able to change to a much bigger company who have state of the art printing presses costing well over $3 million each.     These printing presses can be adjusted at every inch of a sheet to ensure colour consistency, and the sheets are checked against the original colour sample with a spectrometer (a type of light meter) to ensure that consistency is maintained. These samples were created in a UK lab directly from Prof Wilkins’s  research, and every batch is checked on production to have a variance from the original of no more than Delta 3.  Most, if not all, are below Delta 2, and some are under Delta 1. “Delta” is the unit of measurement used in the printing industry for colour variations from an original, when measured by a spectrometer. Delta 4 is the accepted industry standard of tolerance. In an adjoining factory our suppliers also manufacture the actual PET they use for us. The PET they develop for us places a priority on clarity and strength of scratch resistance. They also have an active global research department who are always working to improve quality.

BDA Assured was a programme run by the BDA (British Dyslexia Association) from 20019-2021, which gave the “BDA Assured” badge to resources that were recognised by the BDA as being helpful to people with dyslexia.  During that time, Crossbow reading rulers and coloured overlays were part of the scheme.  This programme has now been discontinued, and will be replaced early in 2022 by a new page of useful resources.   Labels already printed will still carry the BDA assured symbol on them.  New labels will be updated to refer to the new BDA list

We consider our responsibilities to the earth we live on in the development of every new product we make.   

Research into how colour helps was originally done by Olive Meares and Helen Irlen in the early 1980s, working independently in different parts of the world.     Helen Irlen in California went on to trialling tinted lenses and set up Irlen® centres initially in America but now all over the world.  She called the condition “Irlen® syndrome,” and tells the story of how she developed what is now called “The Irlen® method” in her book “Reading by the Colours.”

Professor Wilkins describes how he became interested in what he now calls visual stress in his book Reading Through Colour (Wiley 2003).     He was at the time a professor at Cambridge University and as a scientist with the Medical Research Council he had spent 10 years researching photosensitive epilepsy.    During this time he used electrodes to measure the electrical activity of the brain in people presenting with photosensitive epilepsy.     This led to the discovery that there were geometric patterns with very specific characteristics that enhanced the risk of a seizure.   He then noticed that some friends and colleagues commented that they would get headaches if they looked too long at the patterns he was using.    He conducted further experiments on these people and then others who said they got headaches from reading, noting the results and varying the patterns.     He describes the process in “Reading Through Colour.”    Wilkins records how in 1985 he found an article about colours and helping children to read and built an instrument to test children.      With support from the Medical Research Council and in association with Cerium Visual Technologies, Wilkins went on to develop the ‘Intuitive Colorimeter’ and ‘the curve’ now used in many specialist optometrists’ practices to ascertain the correct colour for lenses.     

There are differences in the testing procedure and outcomes in the 2 systems.    We at Crossbow Education feel the differences are better explained on the sites of the researchers themselves.    We have chosen to go with the procedures and outcomes developed by Arnold Wilkins at Essex University.    

No we do not sell or intend to sell tinted glasses.    If students need a colour for more than over a white page, we consider they need to go to an optometrist or medical professional.  The tint in a spectacle lens would affect everything, not just a page of a book or a computer screen, and is most often a different depth or hue to accommodate the global view.   Specializing optometrists have equipment to do this, and although Crossbow does not have practitioners providing tinted spectacles, we may be able to point to those who do (see paragraph below on where we fit in the pupil path).      

No.   We find overlays in specific colours really help some children read.  Overlays can provide effective ergonomic support for some people who experience visual difficulties when reading; they are not a “cure” for anything. There are some visual difficulties that seem to be particularly prevalent among people with dyslexia; consequently a lot of people who find coloured overlays helpful are also dyslexic.  

Crossbow was founded in 1993 by SEN teacher Bob Hext  to produce multisensory resources to help with reading and spelling, based on his own work with dyslexic children.  In 2004, a teacher in America sent him a yellow – edged plastic strip that she said worked to help children track when reading.     We found this to be very helpful for tracking as it highlighted just one line in yellow or blue so children found it easy to keep their place. The transparent tints also seemed to make the words clearer for some children.  Anne Hext contacted Mark College, a beacon dyslexia school in Somerset, and asked them to look at some designs she had done to develop something in the UK that would help with clarity and tracking.    They said the product would be much more useful if it had the possibility of being used to read on into the paragraph as well as just tracking a single line.      Anne and Bob worked on a suitable design and had them made. A patent was granted for their design, which they called the “Eye Level Reading Ruler.” Their own R and D led them to produce reading rulers first in two colours (blue and yellow), and then five.

By this time Arnold Wilkins and the Optometrists he worked with had started to publish peer to peer validated research on reading through colour.  Anne and Bob met Arnold who advised us to extend our range to ten colours. We acted on his advice, and have followed his research ever since, and he has continued to advise us on colours and shapes. He prefers the bigger A4 overlays to the reading rulers as they do a more comprehensive job at screening out the high contrast pattern glare.    However we find that children generally find the reading ruler to be less intrusive and more often have the courage to use it in the classroom.    Peer-reviewed research in 2019 has shown that the use of a reading ruler increased reading speed by an average of 20%, as opposed to 22% with the larger overlays.

Our process is to inform people about visual stress and help them ergonomically, both in schools and workplaces.  Overlays and reading rulers help many people as they face long hours studying for exams, or in the workplace, on paper or a computer screen,  thus they are a useful ergonomic tool.    We have sold over 2 million reading rulers and received many letters from people saying they have been a “life changer.”    Reading rulers can also start a discovery path for those with visual stress or occasionally other problems.    We explain that our screening is to find a helpful colour and cannot test for what underlying condition is causing the problem.   

We believe that just as the first discovery of colours helping people read was made by actually putting a colour on a page, the same is true today.   Many people who are up to date with their optometrist tests come to us and discover they are really helped by reading through colour. They often don’t realise there may be a visual difficulty: they just assume what they experience is normal until they see the difference a specific colour can make.  

We are happy in our role as ergonomic help to some and as a first step to professional medical help for others.   Either way we direct them back to an optometrist to re-check for general eye health.   Sometimes they take a reading ruler to the optometrist and if the optometrist specialises in Visual Stress they will take further action as the patient requires.    To make it as easy as possible for people to take the next step, we have photocopiable leaflets in the Visual Stress Assessment Pack to give out, telling people where and how to find a specialist optometrist.    We also have a list of optometrists specialising in testing for colours on our website, giving the various qualifications each one offers.  (Note: we are currently working to add a map and other refinements to this list, so it may be down at various times. If this is the case you can ring and ask one of our customer service team to give you a nearby specialist optician, if there is one.)  

Visual Stress is at present the name Arnold Wilkins suggested for the over-reaction that can be recorded in the visual cortex of the brain, not the eye, when looking at certain repetitive geometric patterns.    Text at certain sizes has been shown to trigger this over-reaction in some people, thus causing the text to appear to float, or move or blur. The research suggests that different wavelengths trigger this reaction in different people, which is why a specific colour is needed for each person to filter it out.   The optometrist is of course testing the eyes, so this would not be apparent from a standard NHS eye test.   Children going into their practice with reading rulers and overlays has prompted some optometrists to take an interest and add this specialism to their offering.   Some had seen ‘the colorimeter’ and lately ‘the curve’ and looked at testing visual stress from seeing these instruments.   It remains entirely the optometrists’ choice whether or not they go into testing for a brain problem like visual stress.   

Many people we ask, including teachers, have never heard of a pattern glare test.   Similarly, unless the problem is so severe that the teacher is actively needing to find out what is wrong, the child will not even realise there is a problem and will not go forward for a pattern glare test even if it is offered.    On the other hand, the reading ruler is used extensively in many classrooms, giving children the opportunity to read more easily and start on the path to discovering if they have a visual difficulty.  In the future, it might be suitable to have a simple pattern glare test on all children but at present there is not the structure in place.    

Yes: we do an application called ‘Tint and Track’ which can tint the computer screen and give the option of a virtual “reading ruler” that can be customized according to user preferences. We also stock a range of large overlays called ‘monitor overlays,’ which  can be used on any computer that is not touch screen.  

We have a friendly customer service department who will answer most questions and refer on any they cannot answer.