Investigation into pattern sensitivity and the resulting symptoms of seizures, headaches, and perceptual distortions began in the early 1970’s when Dr Arnold Wilkins discovered that the factors that promote seizures were very similar to the factors that cause headaches. He found that some cases of pattern-sensitive epilepsy could be treated with colour filters. In the early 1980’s, when reports were made for using colour filters to help some reading difficulties, investigation began into the potential use of coloured filters to help with other neurological conditions.
In 1990’s Wilkins developed the Intuitive Colorimeter to determine the optimal filter colour by systematically evaluating the three aspects of colour; hue, saturation and brightness. This equipment has been used to carry out scientific research into this effect, concentrating on defining the condition, clarifying the key indicators, determining the origin, and further developing the solutions.
Research to define the condition
1) Pattern Sensitivity and Visual Stress
Visual stress manifests when viewing certain image types, such as repetitive striped patterns. The intensity of these effects will vary according to individual susceptibility and the precise nature of the pattern, most notably, its spatial frequency and contrast level. An adverse response when viewing stimuli of this type, i.e., striped patterns, has been termed pattern glare. For susceptible individuals, this sensitivity to pattern glare can result in visual stress, giving rise to symptoms of eyestrain, headaches and glare, along with illusions of colors, shapes, and motion.
2) Origins of Visual Stress
The characteristics of the visual stimulus, which cause (or at least contribute in generating visual stress) are sensory in origin and therefore distinguishable from factors of motor origin, such as oculomotor balance, binocular vergence, and accommodation. The origins of pattern glare and visual stress are thought to arise due to cortical hyperactivation.
3) Solutions for Visual Stress:
A large volume of research provides evidence that colour filters reduce Visual Stress. In 1994, while at the Medical Research Council Applied Psychology Unit in Cambridge UK, Arnold Wilkins invented the MRC Intuitive Colorimeter and Precision Tints. This facilitated one of the best-known studies into visual stress. Many studies have also found that the optimal colour needs to be individually prescribed, and sometimes with considerable precision.
3.1. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthal.Physiol.Opt., 14, 365-370 - Wilkins, A.J., Evans, B.J.W., Brown, J., Busby, A., Wingfield, A.E., Jeanes, R., & Bald, J. 1994
3.2. Scotopic sensitivity/Irlen Syndrome and the use of coloured filters: a long-term placebo-controlled and masked study of reading achievement and perception of ability. Perceptual & Motor Skills, 88, 83-113. - Robinson, G.L. & Foreman, P.J. 1999
3.4. Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ. Ophthal.Physiol.Opt., - Lightstone, A., Lightstone, T., & Wilkins, A. 1999. 19, (4) 279-285