Wilkins, A.J., Evans, B.J.W., Brown, J.A., Busby, A.E., Wingfield, A.E., Jeanes, R.J. and Bald, J. (1994). Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthalmic and Physiological Optics, 14(4), 365-370.

If you still have important questions or need specific information you can telephone Avril Shelmerdine on 01206 372381 The NHS pays optometrists a small fee for carrying out a basic eye examination. As the tests listed above are of a specialist nature most optometrists have to charge a private fee for the detailed investigation of people with reading difficulties. The latest estimates are that visual stress is present in around one in five people with dyslexia, but although they may co-exist, visual stress and dyslexia are different conditions The following book provides a review of research in this area and a theoretical explanation for the effects of colourColoured overlays and coloured glasses can increase the speed of reading, although with conventional text the improvement may only be apparent after ten minutes continuous reading when the child would begin to tire were an overlay not used.3 If the text is closely spaced, the benefit is more immediate. It is essential to realise that the appropriate colour for use in glasses is not the same as that in overlays 5. For example, a child may choose a yellow overlay and benefit from blue lenses. The colour of the lenses can only be assessed by optometrists or orthoptists who use the Intuitive Colorimeter 0, or by the use of a very large number of coloured trial lenses. Other methods of selecting coloured lenses may be less likely to select the optimal colour.

When tested a second time, individuals may sometimes choose a different colour, but it is usually a similar colour. The choice of colour may appear random, but it is not!In our opinion, overlays can be used regardless of any simultaneous eye exercises or medical treatment. However, visual perceptual distortions can sometimes be caused solely by binocular vision problems, so it is sensible to have these corrected first. If the distortions remain then coloured filters need to be tried. In 1999, British scientists carried out clinical trials that “found that coloured lenses could help people with visual dyslexia.” 400 children participated in the most recent study where “90% reported a significant improvement in reading, writing and comprehension skills” whilst wearing the coloured lenses. Over the 6-month assessment period, the children showed a minimum improvement rate of 45% for their reading, writing and comprehension skills. How Do Coloured Overlays for Dyslexia Work? The examiner should listen to the client’s description of the distortions, and use this description when trying to decide whether a particular colour reduces the distortions. When tested a second time, individuals may sometimes choose a different colour, but it is usually a similar colour. The choice of colour may appear random, but it is not! 27. What does one do if a child reports a large range of colours beneficial, but cannot make a consistent choice?