Colour permeates school life, from the classrooms and corridors to the playgrounds and dining halls. Think of the jolly rainbow-hued reading corners and art displays at primary school, or the traffic-light systems that let pupils know whether they’re demonstrating good or not-so-great behaviour. And when it comes to sports day and PE, colours tell you what team you’re on.

Even in secondary school, colour is everywhere. For example, a world map in a geography textbook may indicate the gender pay gap from country to country by colour.

It’s not hard, then, to see how a child with colour vision deficiency (CVD) - what many of us know as colour blindness - might have a tough time at school.

“Throughout the whole educational journey, colour is used so much more than it was in the past,” says Jenny Bosten, a visual neuroscientist specialising in colour vision at the University of Sussex Baby Lab. “That can be very confusing for people who can’t discriminate colour.”

Despite what the term suggests, colour blindness doesn’t mean that you can’t see any colour - it means the person’s ability to distinguish between colours is reduced. Think of a pack of coloured pencils. People without CVD would see an array of colours - red, green, yellow, blue, purple and so on. But to someone with CVD, that same set of pencils might appear as a collection of greens, yellows and blues only.

“There are a lot of potential colour confusions for people with CVD. It’s often called ‘red-green colour blindness’, but that term is a bit misleading in that it causes people to think that only red and green are affected,” explains Bosten. “Certain colours will look the same to people with CVD. For example, blue and purple will look the same, teal, red and grey will look the same, as will green, orange, yellow and red.”

So, how many pupils are affected by this issue? Possibly more than you might think. Figures from advocacy organisation Colour Blind Awareness show that 80 per cent of Year 7 pupils have never been screened for CVD and an estimated 50 per cent of colour-blind students are undiagnosed by the time they sit their GCSEs. And it’s the boys in the classroom who are more likely to suffer than girls - about one in 12 men and one in 200 women worldwide are affected by colour blindness. The reason for this is that the most common type of CVD - that red-green colour-blindness - is largely genetic and is carried on the X chromosome.

“Because women have two X chromosomes, if they have one X chromosome with the affected ‘colour-blind gene’ and a second X chromosome which is normal, they won’t be colour-blind,” says Bosten. However, in this scenario, the woman would still be a carrier, so if she went on to have a son, he would have CVD.

So, if as many as one in a dozen boys could be affected, why are the vast majority of pupils not being screened for the condition?

The impact of colour-blindness on school pupils

Colour-blindness screening in schools was scrapped in 2009 - which, Bosten explains, has driven underdiagnosis. In that same year, the Department of Health in England commissioned the Healthy Child Programme: from 5-19 years old guidance, which reviewed the literature relevant to health promotion in children and young people.

“It concluded that they had found no evidence to support screening for CVD and recommended that it be stopped,” says Bosten. “There was only one citation, which was a study based on the 1958 birth cohort study, which actually did conclude that men with CVD were under-represented in certain occupations. In the 1960s, there was much less colour used in education than now, so we think that the evidence base needs updating and the issue needs to be revisited.”

She argues that a lack of diagnosis means that many children are being left behind. “It’s a huge problem in schools. The classroom now is so colourful; different regions of the room are often labelled using colour. Many materials and exercises in the early years classroom are based around colour,” Bosten explains. “For example, colourful Compare Bears are used to educate on patterns. In a ‘complete the pattern’ exercise, the teacher will assume the child doesn’t understand the pattern but, actually, the child with CVD can’t differentiate the colours.”

This is why Bosten, along with her Baby Lab colleague Anna Franklin, has developed ColourSpot, a tablet-based app that can diagnose CVD in “about five minutes”. They describe it as a gamified optometric assessment aimed at children aged 4 and older, where friendly animal characters ask the child to tap the coloured spots they can see on a grey background.

“It makes the colours fainter and fainter, until the child is just guessing, and that tells us what we call their ‘visual discrimination threshold’, which is the faintest colour they can see,” explains Bosten. “This is characteristically changed in CVD, so if we measure the visual discrimination threshold in every child, we can then categorise them into children with normal colour vision and those with CVD.”

The app is funded by the European Research Council and it’s been three years in the making. Bosten and Franklin say it can be administered in schools or by parents, thereby making it more accessible. As Franklin says: “It reduces the costs; you don’t need a trained optician to do it.”

The team is soon to have a paper published in the journal Behavior Research Methods, which demonstrates that the app is effective in comparison with other paediatric diagnostic methods. However, the app is still awaiting approval by the Medicines and Healthcare products Regulatory Agency.

“We’re hoping it will be approved in a year and then we’ll be looking at how we roll it out to schools,” says Franklin.

In the meantime, what can teachers do to support children with, or suspected to have, CVD? It’s often about simple solutions, says Bosten: “It’s about making sure that any information conveyed in the classroom is not just to do with colours, especially the ones that people with CVD find difficult to discriminate. On a map, for example, you could have a grey-scale code and a colour code together.”

Differentiating resources in this way is, of course, an extra step for teachers to take when they are planning and preparing for their lessons. But it is no different, many would argue, from what teachers already do to cater for other types of visual impairment, or other special educational needs: increasing the text size of resources, for instance. And taking that one extra step is surely a small price to pay to be able to offer really crucial support that will help pupils to better access learning.

Bosten suggests an unwillingness to adapt has never been the issue here - teachers are happy to do what they can - but that it is the lack of awareness that is the problem.

“It can be relatively straightforward [to support children with CVD], but I think the awareness just isn’t there,” she says. “That’s partly because the national screening programme ended and now it’s really not on teachers’ radars any more.”

The knock-on effects of undiagnosed CVD cannot be overstated, though. If a child cannot successfully complete a task at school, they might feel like a failure, which could lead to low self-esteem. They might even be misdiagnosed with dyslexia or attentional problems as a result of their CVD. These children are likely to have difficulties across a broad range of subjects, from maths - where they are unable to read pie charts and graphs - through to PE, in which they cannot distinguish between teammates and opponents. If they don’t follow instructions correctly, their actions might even be interpreted as misbehaviour.

Franklin is adamant about the need for change. “At least one boy in every classroom will be colour-blind, so it’s pervasive,” she states. “There are case studies of children who have got severe CVD talking about their experience and it’s really quite powerful. They feel misunderstood. Every day in school is a battle, wondering why everyone else can do the things they can’t.

“They then realise it’s because they can’t see what other people see.”

Christina Quaine is a freelance journalist

This article originally appeared in the 3 September 2021 issue under the headline “Tes focus on..colour blindness”