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fMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine. by Jie Huang, Xiaopeng Zong, Arnold Wilkins, Brian Jenkins, Andrea Bozoki, and Yue Cao[1]
Since the discovery of Irlen Syndrome (Meares-Irlen or Visual Stress)[2] over a hundred studies have been published in numerous peer-reviewed journals in both the North America and Europe. This syndrome is usually associated with light sensitivity and visual perceptual distortions that inhibit learning and cognitive processes. Some light frequencies seem to cause cortical hyperactivation in the occipital region, which can lead to visual perceptual distortions especially when reading, headaches that can turn into migraines, and fatigue. Arnold Wilkins, in particular, notes that this syndrome’s symptoms manifest themselves when looking at repetitive lines, which can be found everywhere (window blinds, roof coverings, escalator steps, etc.), but mainly in reading material. Even the words mom and mummy contain a high number of repetitive parallel lines. Looking at such lines can lead to the appearance of visual perceptual distortions in those who have this syndrome. A number of researchers have shown the benefits of colour (overlays or tints added to eyeglasses) to filter these damaging light frequencies. To be effective, there must be a mix of more than 1,000 colours,[3] hence the nomenclature precision ophthalmic tints. The Irlen Institute in California distributes such lenses throughout the world, marketed under the brand name Irlen Spectral Filters®. In Europe, Cernium is a distributor that pays professor Arnold Wilkins royalties, one of the co-authors of the article, for an invention used in the study described below.
Although supported by numerous scientific studies,[4] the effectiveness of coloured filters has long been met with skepticism from some influential groups in the United States who believed that the validity of this concept was questionable. The study carried out by Jie Huang, Xiaopeng Zong, Arnold Wilkins, Brian Jenkins, Andrea Bozoki, and Yue Cao represents a level of proof, with respect to the scientific method, that even the greatest skeptics will be hard put to brush aside.
Some patterns, such as those viewed in reading material, can induce visual discomfort and perceptual distortions in many people, headaches, and even epileptic seizures in persons whose seizures are triggered by visual stimulations. Visual stimuli are common triggers for migraine attacks, during which hyperactivation of the visual cortex has been noted.
Precision ophthalmic tints (henceforth high precision spectral filters, as per the name given to it at the Irlen Institute) claim to reduce visual distortions and discomfort, and prevent migraines in some patients. The study conducted by Huang, Zong, Wilkins, Jenkins, Bozoki, and Cao (2011) examines the benefits of these filters on cortical hyperactivation during migraines.
A group of 11 migraineurs (experimental group), who were prescribed high precision filters, and 11 control participants (control group, matched in gender and age with the migraineurs), were asked to look at non-stressful and stressful patterns through gray, control coloured, and high precision filters. Participants were not told the order in which the filters were presented during the data collection, using functional magnetic resonance imaging (fMRI).
No differences were observed between the experimental and control groups’ responses to non-stressful patterns. Cerebral activation increased in migraineurs, as opposed to the control group, when viewing patterns through gray and control coloured filters. An absence of low-pass spatial frequency (SF) tuning was also noted in some regions of the visual cortex in the experimental group. However, when high precision filters were used, both cortical activation and SF tuning were normalized in this group. With respect to the distortions observed while viewing stressful patterns, these participants claimed that precision filters offered greater relief than the other two filters. Their perceptual distortions were either reduced or disappeared completely. These results suggest a neurological basis for the therapeutic effect of these filters, which reduce the hyperactivation of the visual cortex among people prone to migraines when viewing stressful patterns through precision ophthalmic filters.
The results from this study clearly show the role of precision filters, such as Irlen Spectral Filters®, in some people who are sensitive to visual stress and its effects on certain brain activities. The effect of stressful patterns described in this study is very similar to the effect on the brain when viewing repetitive lines in reading material. The elements reported in this study therefore suggest greater validity in the use of high precision tinted lenses. The facts presented here far exceed the placebo effect referred to by some critics.
By Jacques Guimond Director, Irlen Atlantic Centre
[1] Huang, J., Zong, X., Wilkins, A., Jenkins, B., Bozoki, A., & Cao, Y. (2011). fMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine. Cephalalgia, 31(8), 925–936. DOI: 10.1177/0333102411409076
[2] Olive Meares, a New Zealander, presented in 1980 her observations regarding the link between the background colour of a text and the font used, and how they influence the number of mistakes and the reading speed. I am not aware of any other contribution from her since. Helen Irlen, a school psychologist in the United States, rediscovered the syndrome (naming it the Irlen Syndrome) without previous knowledge of Olive Meares and published an article on the subject in 1983. She patented her approach, which calls for filters (either coloured overlays or precision filters inserted into eyeglasses). Irlen established a connection between the use of precision filters and improvements in some cases of people with reading difficulties, attention and concentration problems, visual fatigue, distance perception issues, headaches and migraines, head injuries, behavioural problems, autism, and anxiety.
[3] Wilkins, A . J. , Sihra, N., & Nimmo-Smith, I. (2005). How precise do precision tints have to be and how many are necessary. Ophthalmic and Physiological Optics , 25 , 269–276.
[4] Retrieved from [http://irlenatlantique.ca/index.php?] on November 13, 2011