Irlen Scientific Research

A Summary of Research into the Irlen Method

Dr. Greg Robinson and Don Riley review the research into the use of coloured overlays and precision tinted lenses for those with a range of perceptual difficulties that act as significant barriers to learning and achievement.

Background – Origins of the Irlen Method

Helen Irlen, an educational psychologist, began research in 1980 with university students. As Director of the Adult Learning Disabilities University Programme, she obtained a government grant to investigate the mismatch of potential and performance in adult students studying at California State University. Her work established a link between visual disturbance on the page and reading achievement. As the research proceeded, she began to investigate colour filtration as a possible intervention for perceptual difficulties and its effect on the reading process. She found that by using colour, she could eliminate the perceptual difficulties that were preventing students from accessing print and causing physical discomfort during reading.Irlen has been recognised worldwide as the first person to research, categorise and develop a testing method for a specific type of perceptual difficulty. She is also recognised as the first person to develop the technology of systematically using colour, as coloured plastic sheets and coloured lenses worn as glasses or contact lenses, to eliminate the symptoms. Her system has been developed during the past twenty years and the assessment method has been constantly refined and improved.Since this technology has been in use, research has been able to substantiate a deficit in the brain's ability to process visual information and its association with reading disabilities. Twenty years of educational, medical, and academic research has generated a wealth of support for the success of colour in treating these perceptual difficulties associated with Irlen Syndrome. It is important to separate vision and perception since Irlen Syndrome is unrelated to visual skills as assessed by an optometric exam (Evans, Busby, Wilkins & Jeanes, 1995)

People with Irlen Syndrome perceive and interpret their world differently, whether while reading or observing their environment. It is as if they are wired differently. Because they have no other point of reference, most children and adults with this problem are unaware that they have it. As a result, they don't discuss it with others. In addition, they may take it for granted that they experience physical symptoms when reading. They think it is normal to get tired or have a headache or stomach ache when reading or sitting under bright or fluorescent lights. They suffer in silence, wishing they could perform better and please their parents and teachers.Those with Irlen Syndrome report a vast array of symptoms, all of which need to be dealt with by the appropriate colours. The range and severity of symptoms varies from person to person. They include: blurring and movement of print and objects in the environment; flickering, pulsating, swirling, floating of print; white background competing or overtaking the print; visual discomfort such as fatigue, strain, headaches, dizziness and nausea.Most individuals do not have Irlen Syndrome and therefore are not bothered by fluorescent lights, textbooks printed on glossy white paper, white boards, and overhead projectors. But for individuals with Irlen Syndrome, the classroom is a very stressful environment. Many other environments, such as the workplace, restaurants, shopping malls and supermarkets, are equally stressful for those with Irlen Syndrome.

A Subset of Individuals

There has always been some confusion about Irlen Syndrome. Some people have wrongly classified the syndrome as a form of dyslexia. However, the Irlen Method is another way of looking at a subset of individuals who, in reality may not be dyslexic or have ADD / HD or specific learning disabilities, but who may manifest symptoms similar to those displayed by individuals with those disorders. On the other hand Irlen Syndrome may co-exist with these other difficulties. These individuals may or may not have fundamental difficulties in language processing at the level of the phoneme, but they do have difficulty with a subset of perceptual and processing abilities that prevent the easy and efficient use of reading skills, thus interfering overall with learning and attention. When incidence data has been collected on this type of processing deficit, it consistently appears as one layer of difficulty in large numbers of people identified with reading, attention or learning difficulties, with estimates of incidence in the general population of 12% to 20% (Evans, Patel, Wilkins, Lightstone, Eperjesi, Speedwell et al., 1999; Jeanes, Busby, Martin, Lewis, Stevenson, Pointon et al., 1997; Scott, McWhinnie, Taylor, Stevenson, Irons, Lewis et al., 2002). It may not be the only difficulty or major problem, but reducing or eliminating this layer can be very beneficial to the educational process of the individual, allowing them to benefit more from other programs or therapies, and reducing their overall level of difficulty.

Irlen Syndrome: Neither an Optical nor a Medical Problem

Diagnosis and treatment with Irlen Filters has been reviewed by the USA Medical Board, and has been determined as not the practice of medicine; it has also been reviewed by various USA Boards of Optometry and has been found not to be the practice of optometry. Binocular and accommodative anomalies may occur in conjunction with the syndrome, but are not considered to be the underlying physiological basis of the condition (Evans, Patel, Wilkins, Lightstone, Eperjesi, Speedwell et al., 1999; Evans, Wilkins, Brown, Busby, Wingfield, Jeanes, & Bald, 1996; Evans, Wilkins, Busby, & Jeanes, 1996; Scott, McWhinnie, Taylor, Stevenson, Irons, Lewis et al., 2002; Simmers, Gray, & Wilkins, 2001). The problem is not a medical condition. It is not pathological, nor a disease. It is not, as far as is known, a visual problem due to any abnormality of the eye. As a perceptual problem, it is similar to other processing problems (visual and auditory) which are diagnosed by psycho-educational testing and treated within the educational system.In the USA, there are over 4,000 schools that have implemented the Irlen method. Worldwide, over 100,000 people have been provided with Irlen Filters; Arizona has passed a bill designating funding for a pilot project and within two years Irlen screening will be mandatory in all schools in that state; California has funded a pilot project for the diagnosis and treatment of inmates at Mule Creek Prison, and Alabama has recognised Irlen Syndrome/Scotopic Sensitivity as a learning disability. In the United Kingdom, the Medical Research Council has funded extensive research into the Irlen Method and coloured filters at Cambridge University and now at Essex University. There have also been studies into the prison population affected by the syndrome as well as studies reporting the positive effects of coloured overlays and filters on reading comprehension, accuracy and speed.

The Research

Research projects are ongoing around the world. Some of these concern the use of Irlen filters, others are investigating the principle of colour filtering. In a recent survey, it was possible to identify 63 studies involving coloured overlays, coloured computer monitors or coloured lenses. Many of these would be considered to have adequate experimental controls and many were published in peer reviewed journals, conscious of guarding their reputation by not accepting papers with serious methodological flaws. Of the 63 studies reviewed, only 6 produced fully negative results, with 42 finding positive results for particular reading skills, 4 having mixed results and 11 finding improvements in accommodation facility, eye movements while reading, and reduced headaches/migraine. A number of these studies have used placebo controls (Bouldoukian, Wilkins, & Evans, 2002; Jeanes, Busby, Martin, Lewis, Stevenson, Pointon et al., 1997; Robinson & Foreman, 1999; Wilkins, Evans, Brown, Busby, Wingfield, Jeanes, & Bald, 1994; Wilkins & Lewis, 1999).

In addition, a credible scientific theory has been presented and discussed in the literature for some years. This theory relates to a deficit in the magnocellular visual neurological pathway. A recent review of research and series of studies relating to this theory has been published by Chase et al. (2003). The paper by Chase et al. reviews a number of studies which suggest that red light disrupts magnocellular tasks and that the use of blue filters (which filter red light) results in an improvement in reading performance.

In Australia, Associate Professor Greg Robinson from the Special Education Centre at the University of Newcastle, has completed a placebo-controlled study of the use of Irlen Filters, and has published numerous other papers on the subject, including evidence of biochemical anomalies in people with Irlen Syndrome. Fundamental research is being conducted by Dr Jeff Lewine, Associate Professor of Radiology and Director of Functional Brain Imaging, University of Utah, and Professor G. Barbolini, Universita Degli Studi Di Modena, Dipartimento Di Scienze Morfologiche E Medico, Italy. Brain research at the cellular level has provided new information regarding the operation of the visual pathways in dyslexics as opposed to normal readers, and provides a plausible explanation for the demonstrated effectiveness of Irlen filters whether in the form of lenses or acetate sheets. A single-subject study carried out in the US Naval Air Warfare Center Weapons Division purports to demonstrate, among other things, that the Irlen effect is real, and that varying the energy spectrum presented to the eye of this dyslexic individual was capable of altering visual and cognitive performance for better or worse, to a significant extent.

In light of the ongoing research and the results of clinical surveys, it seems important that this technology be widely available to individuals who suffer with learning disabilities, whose disabilities are not easily resolved by other methods, or for whom Irlen Syndrome may constitute one layer of the disability. While the Irlen Method does not assist all people with learning disabilities, it constitutes a relatively cheap, non-invasive and safe intervention that appears materially to assist a significant number of people with learning disabilities.

Synopsis of some Research Papers

In the United Kingdom, the main researchers have been Professor Arnold Wilkins of the MRC Applied Psychology Unit, Cambridge, and Dr Bruce Evans of the Institute of Optometry, London. While Arnold Wilkins is partly commercially involved with a colour diagnostic method, neither of the above researchers prescribes Irlen lenses.

A study by Wilkins et al. (1994) used a double masked, placebo controlled design with subjects reporting significantly fewer symptoms when the correct coloured lenses were worn. The Wilkins et al. (1996) study found an immediate and significant increase in reading speed when using coloured overlays.

Evans et al. (1995) investigated the degree to which subjects with symptoms of Scotopic Sensitivity/Irlen Syndrome have undetected optometric problems. It was found their difficulties were primarily of a non-optometric nature and thus do not come within the field of optometry.

The Tyrrell, Holland, Dennis, and Wilkins (1995) study found children read significantly more slowly without a chosen coloured overlay than with it. These effects took 10 minutes of reading time to occur, which verifies the claims of a progressive distortion of print frequently reported by subjects. A later study demonstrated that improved speed of reading could not be attributed to placebo effects nor to optometric or orthoptic factors (Bouldoukian, Wilkins & Evans, 2002).

Another group of researchers centre on Florida with Mary Williams as a key person. This group of researchers does not have any commercial involvement in the use of colour, and have worked independently with colour, having no association with the Irlen technique. The study by Williams et al. (1992) found significant improvements in reading comprehension and reading accuracy when using coloured overlays and coloured computer monitors.

A third group of researchers centre on the University of New South Wales. They also have worked independently from Irlen and do not have a commercial involvement in the use of colour. The main researchers are Robert Elliott, Professor in the Education Faculty and Stephen Dain, Associate Professor in the Faculty of Optometry.

Other researchers at the University of New South Wales (Croyle, 1998) have found a significant improvement in a speeded classification task under certain coloured background conditions, which supports the concept of a deficit in the transient visual processing system as outlined in the Williams et al. (1992) article. If the deficit is identified as a visual-perceptual or visual processing problem, it does not lie within the field of optometry.

Clinical research in Sydney (Whiting et al., 1994) has shown that individuals wearing Irlen lenses for six years indicate continuing improvements in a range of symptoms, from poor reading comprehension to headache.

Associate Professor Greg Robinson from the University of Newcastle is involved in dispensing Irlen lenses, but his research has been published in peer review journals that are conscious of the need for research to be methodologically sound.

A first paper (Robinson & Conway, 1994) found significant improvements in reading comprehension and rate of reading for a group of subjects using Irlen lenses when compared to a control group. Both groups had a similar degree of reading difficulty.

A second paper (Robinson, Foreman, & Dear, 2000) investigated the familial incidence of symptoms of Scotopic Sensitivity/Irlen Syndrome. It was found that for children who have symptoms, there was an 84% chance of at least one parent showing similar symptoms.

A third paper (Robinson, 1994) is a review of current evidence to that date, with the methodological flaws of both positive and negative studies discussed. The review provides a good overview of the range of research undertaken. The literature review in the Robinson, Foreman and Dear (2000) study would provide a more recent supplement to this.

A long-term placebo controlled double masked crossover study that was funded by the Commonwealth Department of Human Services and Health has found three year gains in comprehension and two year gains in accuracy over the 20 months study period for 3 experimental groups, compared to a one year gain for the control group. (Perceptual and Motor Skills, March, 1999). Robinson has also found significant gains in comprehension and accuracy over a six-month period in a recent study that involved an experimental group and two control groups, one not using Irlen filters, and one whose application of Irlen filters was delayed by three months. The comprehension and accuracy effects tended to plateau after three months, however. Self-esteem was also measured and improved significantly (Robinson & Conway, 2000, 5(1), 4-13).

Robinson and colleagues (Robinson, Roberts, McGregor, Dunstan, & Butt, 1999; Robinson, McGregor, Roberts, Dunstan, & Butt, 2001) have identified a number of biochemical markers for visual processing problems related to Irlen Syndrome. The Robinson et al. (1999) study found significant differences in a number of amino and organic acids, which suggested an alteration in protein and tissue metabolite turnover, which could be indicative of immune system dysfunction and the presence of infection, which in turn may influence the metabolism of fatty acids. The Robinson et al. (2001) study found a significant increase in long chain polyunsaturated acids and a reduction in the odd-chain saturated fatty acid C17:0 (heptadecanoic acid) between the low and high symptom Irlen Syndrome groups. A further study (Sparkes, Robinson, Dunstan, & Roberts, 2003) investigated both children and adults with symptoms of Irlen Syndrome. The Irlen Syndrome group had lower mean levels than the control group for most n-3 and n-6 essential fatty acids. Cholesterol levels were also decreased for the IS group and lower cholesterol levels can be a marker of infection, which in turn may influence the supply of fatty acids.

It is not appropriate, in this important area, to conduct a numbers war with the side having the greatest number of positive studies being declared the winner and the losing side having its research dismissed (as is constantly occurring in the debate about methods of teaching reading). In the interests of balance, we have included both positive and negative studies so that readers may judge for themselves, the merits of the case. However, the case for Irlen lenses has not been fairly stated in the past, and we have provided the above information in an attempt to rebalance the situation. In particular, we were concerned that among the many emerging methods, Irlen has been one of the few identified for negative comment, especially as there are many other areas that do not have the wide research support that this method is now receiving.

Regarding the probable anatomical mechanisms involved in the studies, the papers by Livingstone et al., (1991) and Lehmkuhle et al. (1993) appear to demonstrate the existence of a defective visual pathway in at least some dyslexic individuals, while the report from Lewine et al. from New Mexico (now Utah) indicates that a positive effect on neural organization can be observed in individuals wearing Irlen lenses when subject to magnetic source imaging. This study at the University of Utah Centre for Advanced Medical Technologies (submitted for publication) has resulted in the following observations, among others:

  • "This study provides objective physiological evidence for a neurological correlate (and perhaps basis) of scotopic sensitivity syndrome. Specifically, subjects with SSS demonstrate disordered visual information processing when compared to control subjects."
  • And again,"Perhaps the most interesting aspect of the present study is the objective evidence for a physiological effect of Irlen lenses. The slowing of the early component of the evoked response probably reflects little more than the fact that the lenses reduce the luminance by a factor of 1.5-3 (depending on the particular set of lenses). The effect at 180 msec cannot be explained easily in the same manner. Rather, the data suggest a true alteration in visual information processing by the Irlen lenses. Interestingly, this effect does not seem to influence the 220 msec component. This suggests that the 180 and 220 msec response components reflect parallel rather than sequential processing by providing objective evidence for the effect of lenses, it can now be reasonably argued that anecdotal reports of the effectiveness of Irlen lenses should not be dismissed out of hand."

A full list of research and references can be found on the web site

At the time of this writing, Dr Greg. Robinson was an Associate Professor, Special Education Centre, University of Newcastle, Callaghan, 2308, Australia; he was also the Chair of the Australian Association of Irlen Consultants, AAIC. He has since passed away.

Don Riley, M.A. is an Irlen Diagnostician and the Chair of the European Association of Irlen Diagnosticians