Colored overlays have been shown to reduce visual stress and increase reading fluency in about 20% of school children. There is doubtless more than one reason, and placebo effects probably contribute. In 5% of children the increase in reading speed with overlays is greater than 25%, but occurs only when a sufficient number of colours is available from which to choose the optimum. 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 colour optimal for overlays differs from that optimal in lenses. The shade usually has to be selected with precision in order to obtain beneficial results. The symptoms of visual stress (eye-ache and perceptual distortions) and the benefit from colour are sometimes collectively refered 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 coloured 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 overlays systems, the "Intuitive Overlays" offer a sufficient range of colours and have been shown to increase reading speed. They can be obtained from ioo sales. Cerium Visual Technologies sell similar overlays. Suitable techniques for testing with overlays are given in the book "Reading through Colour" by Prof Wilkins, published by Wiley. You can obtain a complete set of Wilkins' publications , and a selection of other recent relevant papers. There is also a set of frequently asked questions (with answers!).You can also obtain a video entitled "Reading with Colour" in which children talk about their experiences with overlays, and a test with overlays is demonstrated.

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. There is a support e-group for those who suffer from Visual Stress (perceptual distortion and eye-strain, treated with coloured filters). There is also a telephone helpline on +44 1206 872130 (01206 872130 within the UK).

Shareware software allows computer users to select the colour of the foreground and the background of their computer monitor. There is software compatible with Windows 95 available for download from this site, and software compatible with with more recent Windows operating systems (Screen Tinter LITE) available for download. The software is useful because it allows you to adjust the colour when you are working on the application you usually use, but you can also adjust the background colour in recent Windows operating systems by following instructions on how to use the Control Panel.

There is a "Society for Coloured Lens prescribers" from which a list of prescribers can be obtained. The society members have subscribed to a code of evidence-based conduct.

A Sciart project has explored visual stress from complex images.

You may be interested in a site for information on eye care and vision for people with learning disabilities

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.