Coloured lenses are neither a cure nor quackery. If people see them in either light “they’ve misunderstood what it’s about”, says Simon Barnard, one of a growing number of high street optometrists who are supplying glasses with coloured lenses to children in an attempt to help them with their reading difficulties. “We all pooh-poohed the idea at first,” he confesses.

Meanwhile teachers can, for the first time, have direct access to transparent coloured overlays to place on a page of type, and use instructions and information about the process without having to go through any special training.

Such a situation would have been hard to foresee even two or three years ago. The claims by the Californian psychologist Helen Irlen that colour could influence a child’s ability to read - initially met in the United States with incredulity and derision - were still viewed with widespread scepticism in the UK, especially amongst academics and optometrists (TES, July 3, 1992).

Part of the problem was a general feeling that there was no proper scientific evidence of the validity of her claims. The commercial nature of her operation, in which only specially trained screeners could operate the tests, was also criticised. And the Irlen package was expensive.

Meanwhile, however, anecdotal evidence was building up from teachers, many of whom were finding coloured overlays a useful aid. Children who had been experiencing headaches when reading, or finding that the words were moving about the page, were suddenly able to make better progress. There were growing calls for independent academic research to be initiated.

Today the landscape looks very different as hard evidence on the effect of colour begins to emerge. Last month the findings of an experiment with children in Warwickshire schools were published. Carried out by Arnold Wilkins at the Medical Research Council (MRC) applied psychology unit in Cambridge, the research was designed to eliminate the “placebo effect”.

Sixty-eight children who regularly used coloured overlays to help with their reading were given two sets of lenses for one month in random order, one with the appropriate colour, the other without. The children, who could not tell which lenses were which, kept diaries recording symptoms of eye-strain and headache - both of which can adversely affect reading. Their record revealed that such symptoms were less frequent when they wore the appropriately coloured lenses.

Other small-scale research within schools is also producing positive results. “It’s the first time that the use of colour has had a good rigorous trial, so that professionals can use it happily,” says optometrist Anita Lightstone, who is employed by Cerium Visual Technologies. Last year the company was licensed by the MRC to make a new instrument, the intuitive colorimeter, a form of “light box” where children look at a page, twiddle some knobs, and find the colour that is most appropriate for their needs. The results can be produced to a high degree of precision in the form of tinted lenses - as many as 6, 700 hues are available for the tinting process.

The colorimeter is now being used by more than 40 high street optometrists in England, Scotland and Northern Ireland, all of whom have been trained by the MRC and the College of Optometrists. The company has already supplied more than 5,000 pairs of lenses during its first year.

Anne Busby, who teaches at Upbury Manor Secondary School in Gillingham, Kent, is one of many teachers who are convinced of the usefulness of overlays, which she recommends to many children with learning difficulties. “The children say it makes it much more comfortable for them to read,” she says. “And parents tell me they use overlays when they’re reading for pleasure.”

If the children are still finding the overlays comfortable after half a term, she is happy for them to consider using lenses - there are two optometrists providing the service within a reasonable distance. But, like others involved with the process, she gets irritated by misleading publicity in the media.

“They keep saying that colour is a cure, but it’s not. The trouble is that children pick this up and get frustrated if it’s not helping after a couple of weeks. It can definitely help, but it’s only a small part of dealing with reading difficulties, and it has to be persevered with.”

Teachers who want to find out if children are suffering from what is now generally called the Irlen Syndrome can get hold of a pack of overlays from Cerium which cover the whole colour spectrum. The package includes a set of screening instructions as well as background information.

Judith Martin, an infant teacher at William Westley Primary School in Cambridge, has often made use of overlays. Over the past two years she’s found that, out of a class of 30, five pupils at any one time have benefited from using them. She’s at pains to emphasise the relative simplicity of the screening process.

“Any teacher can offer the help that I’ve been able to provide,” she says. “The process of examining the child may sound long and complicated, but in fact it takes about 10 minutes, and is simple enough to carry out in class time. ”

The examination involves testing out different overlays on a text, inviting the child to say whether the colour changes the letters in any way. By a gradual process of elimination, the teacher ends up with the filter that best reduces the distortions that the child reports.

However, allowing any teacher to be involved in this way is not universally seen to be a good thing. At the 10 Irlen “centres” in England - there is also one in Scotland, and may soon be one in Wales - the whole process of screening, assessment and the provision of lenses has to be carried out by a trained diagnostician franchised by the Irlen Institute.

“With untrained teachers it’s much more of a hit and miss affair,” says Joan Hillary, who runs the centre covering the Manchester area. “If you don’t know what you’re looking for, you’ll miss a lot of people: you’ll spot the dramatic ones, but not the less obvious. Our system is more thorough.”

She also voices reservations about the Cerium colorimeter. “I’m concerned that the page is tinted: that’s not a safe way of selecting the tint, it’s not likely to get the optimum one. I also feel we score better in that. With the colorimeter they’re looking at the eyes only, while we look at the whole child.”

There are also, inevitably, disagreements about the monetary value of the two schemes. The Irlen package costs a maximum of Pounds 265, excluding the price of frames for the lenses; the MRCCerium route involves spending Pounds 42 on the overlays, and a further Pounds 55 at the optometrists, for checks and for the lenses.

Most academics and researchers now agree that Helen Irlen effectively blazed the trail in this field. The fierce academic and scientific disputes seem to be a thing of the past; they have been succeeded by a cooler phase of more rational inquiry.

A list of optometrists providing the service can be obtained from Cerium on 0580 765211. The Irlen centres have no central office, but are based in London, Manchester, Bradford, Bury St Edmunds, Leicester, Maidstone, Chard, Edinburgh and Belfast.