Dyslexia and the use of Coloured lenses

What is Dyslexia?
Dyslexia is a reading difficulty which is not fully understood, but which is becoming increasingly identified as a significant cause of learning difficulties. Many people who suffer from dyslexia also suffer from poor near-focussing ability, and/or instability of their binocular vision system. These vision problems can often be greatly relieved by binocular vision exercises and/or the use of colour filters. Colour filters can be either colour overlays or colour filter lenses.

In this practice we examine both children and adults with dyslexia, spending more time with them than most patients in order to determine the nature of their visual deficiency, if there is any. When the problem is purely a binocular vision imbalance, then spectacles, if necessary, and exercises are prescribed.

Scotopic Sensitivity Syndrome
If the problem lies deeper, in the area of the brain responsible for visual perception, then the examination becomes more subjective as the patient is asked which colour overlay makes reading material easier to see. This is assessed objectively by checking the speed of reading with the colour overlay versus without the colour overlay. When there is an indication that a colour filter would benefit the patient, we prescribe a colour overlay for them to use. If the colour overlay proves helpful, the patient is then said to have Irlen-Meares Syndrome or Scotopic Sensitivity Syndrome, and can be further helped by wearing colour spectacle lenses.

Colorimetry
The colour that is best suited for the patient for spectacle lens wear is determined using a Colorimeter, an instrument that illuminates text with a specific colour, which is a specific hue, saturation and brightness. With coloured spectacle lenses, the patient's entire field of view is coloured. This is instead of just a small portion, as in the case of using a colour overlay. Consequently, the colour that works best with spectacle lenses is different than the colour of the best overlay. The patient is asked to look into the colorimeter at a script, and tell the optometrist which combination of hue, saturation and brightness makes the script easiest to read. Although colorimetry is highly subjective, those patients who are 'colour sensitive' in their dyslexia are surprisingly consistent in their responses. These patients tend to show greatly improved reading speeds and reading accuracy using a colour interface such as the overlay or tinted spectacles.

Mr Austen, standing, is pictured using the Colorimeter to assess which colour helps the patient to see written script more clearly. The patient is shown viewing the script in the Colorimeter, where the script is illuminated by a specific colour - a unique combination of hue, brightness and saturation.