What do you see when you look at a page of text. Some people, usually children, see more than letters or words. They see things that are not really there: illusions such as movement of the words, movement of the letters, blurring, colours or shapes. Children describe the distortions in a variety of ways: They may say the letters "fizz", "wobble", "shimmer", "fly of the page", "drop off the end of the line", "the page comes up and hits my eyes the white paper may glare and cause eye strain or headaches.
The result in perceptual distortion and visual discomfort may interfere with reading. The distortion is common in children who have binocular vision problems (for which conventional treatment with exercises may be appropriate). It can also occur quite independently of any ocular problem in people whose eye sight is otherwise perfect. Frustration and low self-esteem can occur in children who are under-achieving due to visual stress.
Scientific research has shown that visual stress from reading can be reduced by colouring the page using spectral filters. The filters are either placed directly over the page (these are known as coloured overlays) or they are worn in spectacles (Eye Bright tints or Precision Tints). The Eye Bright Test provides a way to measure colour preference, as well as giving an indication of light sensitivity. It enables an informed choice of tint to be made, which in turn helps to assess the need for further investigation.
Coloured overlays are ideally used for initial screening of patients who exhibit symptoms of visual stress. Patients who gain benefit from a specific overlay should receive a full eye examination prior to assessment using the Intuitive Colorimeter. The Intuitive Colorimeter is an instrument designed and developed by the Medical Research Council Applied Psychology Unit, for selecting the optimum colour for the relief of Visual Stress in Dyslexia, Migraine and Photosensitive Epilepsy.
Research has shown that these patients will always almost obtain greater benefit from Precision Tinted Lenses then from the overlay and that the colour of the tinted lens will almost always be different from the colour of the overlay.