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The use of colour to treat visual discomfort and perceptual distortions (visual stress) has been the subject of recent controversy.
Many schools are introducing LED lighting. Some LED lamps flicker and some do not. There is little difference in price. Make sure your lighting does not flicker. Even lamps that are sold as flicker-free can flicker at high frequencies. This flicker may be invisible but can cause headaches and malaise.
Colored overlays have been shown to reduce visual stress and increase reading speed on the Rate of Reading Test (meaningless text in which common words are presented in random order). The increase occurs only when a sufficient number of colors is available from which to choose the optimum, which differs from one individual to another. A variety of controlled trials have shown that placebo effects are not a sufficient explanation for the increase in reading speed. Colored glasses have been shown to reduce headaches in open trials and also in two small-scale trials using a double-masked protocol. The color optimal for overlays differs from that optimal in lenses. Imaging studies of patients with migraine have shown that it is only when the shade is precise that a reduction in an otherwise abnormally large blood oxygenation occurs. Given the general association between elevated blood oxygenation and visual discomfort, this tends to support other evidence that a precise shade may be necessary for a beneficial clinical effect. Visual discomfort and perceptual distortions and the benefit from color are sometimes collectively referred to as 'visual stress' (preferred) or 'Meares-Irlen Syndrome', and sometimes as 'Irlen Syndrome' (USA), or (formerly) 'scotopic sensitivity syndrome', a misnomer.
Helen Irlen was one of the first to promote the beneficial effects of colored filters. Her approach remains controversial. The research work described in these pages follows from studies conducted originally in collaboration with members of the Irlen Institute, but subsequently quite independently of this organisation. A recent summary of the scientific literature is available.
Unlike some other recent systems of overlays, the "Intuitive Overlays" offer a large range of colors and have been shown to increase reading speed. They can be obtained from ioo sales. Cerium Visual Technologies sell similar overlays and Crossbow Education now sell an A4 pack with a large range of overlay colors. Suitable techniques for testing with overlays are given in the book "Reading through Color" (Wiley 2003). You can obtain a complete set of Wilkins' publications , and a selection of other recent relevant papers. There is a set of frequently asked questions (with answers!).
There is a set of forms containing suggestions for teachers in high schools and colleges. There is a page of information for optometrists. The optometrists who use the Intuitive Colorimeter are listed on the Cerium Visual Technologies website and there is a list of those who have undertaken professional development and subscribed to a Code of Conduct on the site of the Society for Coloured Lens Prescribers.
Software allows computer users to select the color of the foreground and the background of their computer monitor.
The propensity of complex images to provoke discomfort can be quantified.
You may find some of these links useful.
If you have any questions or comments please feel free to contact Arnold Wilkins
Declaration of interest: The Medical Research Council (MRC) owns the rights to the Intuitive Overlays and Intuitive Colorimeter. Professor Wilkins was employed by the MRC and receives an Award to Inventors, based on royalties.
Arnold Wilkins 2019