Scotopic sensitivity syndrome
Scotopic sensitivity syndrome (SSS), also known as Visual Stress, Irlen Syndrome, and Asfedia, is a condition relating to the interaction of the central nervous system and the eyes at a physiological level with light. The effects of SSS are most noticeable during activities associates with reading, but an individual with the condition may notice the condition's effects in other activities. The exact cause of SSS is currently under debate within the scientific community. In addition, the scientific community has not reached a consensus on the most efficient method for treating the condition. However, in a joint statement, The American Academy of Ophthalmology, American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus and American Association of Certified Orthoptists firmly repudiated the use of lenses for treating SSS, stating that there was no scientific evidence supporting their use.
In the early 1980s New Zealand teacher Olive Meares described the visual distortions some individuals reported when reading from white paper. At the same time, American therapist professor Helen Irlen wrote a paper about the use of coloured overlays aiding the reading abilities of some people. Similar symptoms were separately described by Meares and Irlen; each unaware of the other's work. Irlen, who was the first to systematically define the condition, named her findings "scotopic sensitivity", though in the discussions and debates over the following years some referred to it as Meares-Irlen syndrome. There remains to this day stark controversy over whether non-Irlen-certified Meares-Irlen Syndrome and the original Irlen Syndrome are the same condition. Irlen Syndrome for example, seems to include a broader array of symptoms, including severe variants of the core condition. Basic testing for scotopic sensitivity was tried by optometrists, opticians, and orthoptists in UK hospitals, and by optometrists and opticians in private practice employing a technique that used the Intuitive Colorimeter, developed under Medical Research Council license. An alternative approach to correct Irlen Syndrome was also tried by Orthoscopics franchise in the UK, with wide colour coverage and tints manufactured by Hoyato match. Other commercial organisations have produced sets of therapeutic tints, although most have not received scientific evaluation.
The disorders have been studied in several institutions, including the Psychology Department at Essex University, the former Applied Psychology Unit, Cambridge University in England, and in the case of Meares-Irlen Syndrome, Visual Unit at Glasgow Caledonian University in Scotland. As of 2012[update] the Visual Stress Unit offered non-commercial diagnostic and therapeutic services to individuals, and provided advice to the Scottish National Health Service.
In Australia, Irlen Syndrome was researched by Paul Whiting MA.(Hons), DipEd., L.Mus.A, Th.C., PhD. at the University of Sydney. He was Senior Lecturer in the School of Teaching and Curriculum Studies in the Faculty of Education. He was also Director of the Evelyn McCloughan Children's Centre at the University of Sydney, a centre for children and adults with learning disabilities. Paul set up the first Irlen Dyslexia Centre in Australia, which operated within the Children's Centre at Sydney University for more than fifteen years. Irlen Syndrome was also studied in Australia by Greg Robinson (1944-2008) BA, Dip Ed, MEd (Hons), PhD, MAPsS, at the University of Newcastle. He was director of the Special Education Centre within the School of Education.
In the USA, peer-reviewed literature on the topic suggests that much is unknown about the cause of these disorders, ranging from the 2011 study in the journal of the American Academy of Pediatrics Irlen Colored Overlays Do not Alleviate Reading Difficulties and the 2012 study in the journal Brain Topography A Functional Neuroimaging Case Study of Meares–Irlen Syndrome. The first, purely in relation to Meares Irlen Syndrome, finds that there is no evidence for one of the fundamental claims of therapeutic benefit, the second which focused primarily on Irlen Syndrome did however find compelling evidence of unique brain function linked to the syndrome.
American psychiatrist, Daniel Amen, Medical Director, Amen Clinics Inc., who in 2004 had screened Irlen patients for over 10 years, performed before and after brain scans of patients with Irlen Lenses. He found SPECT 3D evidence that while reading, their brains appear more balanced.
Diagnostic impressions using functional brain imaging are also confirmed by behavioural pediatrician and psychiatrist, Robert Dobrin. These are consistent with the work of psychologist, Andrew Yellen and Thomas Schweller, a board certified neurologist and professor of neurology at UC San Diego, who studied Irlen Syndrome utilising Visual Evoked Responses (VER) and documented the Yellen-Schweller effect.
Similar findings were presented at the 45th Annual Conference of the International Military Testing Association in Pensacola, Florida, in the paper, Perceptual Dyslexia: It's effect on the Military Cadre and Benefits of Treatment, by Susann L. Krouse and James H. Irvine. The U.S. Naval Education and Training Command (NETC) sponsored the Naval Aerospace Medical Research Laboratory (NAMRL) to assess the prevalence and possible impact of Irlen Syndrome.
The findings of Amen are also consistent with a Magnetoencephalographic study by Jeffrey David Lewine, John Davis, Sherri Provencal, James Edgar, and William Orrison, Jr, conducted at The Center for Advanced Medical Technologies, The University of Utah School of Medicine, Salt Lake City, Utah, and Department of Psychology, The University of New Mexico, Albuquerque, New Mexico.
Bibliography of all Irlen Research at dyslexiaservices.com.au
Developmental Dyslexia has been documented in Proceedings of the National Academy of Science, with major studies into Irlen Syndrome published in Annals of the New York Academy of Sciences, Australian Journal of Learning Disabilities, Australian Journal of Remedial Education, Behavioural Optometry, Focus on Dyslexia Research, Journal of Correctional Education, Journal of Research in Reading, Journal of the American Optometric Association, Ophthalmological and Physiological Optometry, Perceptual and Motor Skills, The Australasian Journal of Special Education and The Bulletin for Learning Disabilities.
These studies: http://www.dyslexiaservices.com.au/Journals.htm
Scotopic sensitivity syndrome is based on the theory that some individuals have hypersensitive photoreceptors, visual pathways, and/or brain systems that react inappropriately to some wavelengths of light. Vision occurs when photons are detected by the retina, initiating a biochemical process affecting the visual pathways and deep structures of the brain. A growing number of researchers are taking an interest in the view that inappropriate biochemical processing has the potential to cause physiological and/or visual perceptual problems. Many of these problems are grouped together under the label "scotopic sensitivity syndrome".
In simple terms, the theory is that some signals from the eye are not getting to the brain intact and/or on time. Although the eye might be functioning correctly, the brain receives what is like a double exposed picture where the location of items is confused. The brain tries to filter out the bad information and so the conscious mind receives a reconstructed image. That image may be of the items moving (the brain constantly changing its best guess of what is there), blurred outcomes (inability to form a view of what is there), gaps in wrong spots, and a variety of other minor errors. There may also be exhaustion (from the mental effort to unscramble) and sore eyes (from the eyes constantly seeking extra data to aid the process). The problem is worst where different colours do not all give a similar outcome. In nature you get a lot of consistent data but on a man made item (paper, for example) there might be only a limited colour set: the condition does not generate practical problems where there are lots of redundant data for the brain to use.
The pragmatic response by Irlen was not to try to fix the problem but to avoid it. By filtering out the light most likely to generate problem signals to the brain, she was able to improve the likelihood that the brain will correctly distinguish between good and bad information. It also seems likely that in some individuals, over time the brain learns which colours are the problem items and improves its ability to reconstruct an accurate image.
One or more of these symptoms may be related to the condition:
- Nausea, including visually related motion sickness
- Problems with depth perception (catching balls, judging distance, etc.)
- Restricted field of view and span of recognition
- Discomfort in presence of fluorescent lighting
- Discomfort with busy patterns, particularly stripes ("visual stress" and "pattern glare")
- Discomfort with extreme conditions of bright/dark contrast (i.e. backlighting)
- Discomfort or difficulty reading (reading involves busy patterns, particularly stripes. People with strong symptoms of the syndrome find it very difficult to read black text on white paper, particularly when the paper is slightly shiny.)
- Text that appears to move (rise, fall, swirl, shake, etc.)
- Losing text content and only seeing rivers of white through the text
- Words moving together becoming one unrecognizable word
- Attention and concentration difficulties
- Seeing the part and losing the whole
- Epileptic seizure related to strobing or pattern glare
The use of tinted lenses in glasses and coloured overlay sheets has been prescribed by many doctors; however, the efficacy of such treatment is questionable. It has been felt to be efficient treatment by some, and inappropriate by others, because more conventional treatments are sometimes more appropriate.
The College of Optometry (UK) has specified guidelines for optometrists who use the colorimeter system. A society for coloured lens prescribers has been established to provide a list of eye-care practitioners with expertise in the provision of coloured lenses for the treatment of visual stress.
The Promethean Trust, a Norwich-based charity for dyslexic children, has found that the use of a cursor has eliminated the need for coloured overlays or lenses. The cursor is simply a piece of card or plastic, approximately the size of a credit card, with a notch cut out of one corner. The reader uses this to track print from left to right, and at the same time the card prevents the eyes from wandering ahead.
The Irlen Method uses coloured overlays and tinted lenses in the form of glass or contact lenses. The method is intended to reduce or eliminate perceptual processing errors; the resultant retiming of visual signals in the brain improves the reading difficulties associated with scotopic sensitivity syndrome.
Skepticism relating to scotopic sensitivity syndrome's exact pathology, has evolved on several fronts:
- Whether it exists as a distinct, predictably identifiable disease with a reasonable pathophysiological mechanism, or whether instead a range of symptoms from other conditions are not being placed under this convenient heading;
- Whether it is causally or incidentally related to dyslexia, autism, or other conditions; and
- Whether existing methods of scotopic sensitivity syndrome treatment are appropriate and effective.
A 2009 report by The American Academy of Pediatrics (AAP) does not believe that there is conclusive scientific evidence for the use of coloured lenses (one treatment used to relieve symptoms of Scotopic Sensitivity Syndrome) although it does acknowledge anecdotal evidence to the contrary. When discussing its scientific basis, the AAP mentions that "[t]he method used to select the lens or filter color has been highly variable,the color selection has also shown considerable variability,and the test-retest consistency has been poor" (p. 843)
The association of scotopic sensitivity syndrome and dyslexia has been challenged by many authors in both the optometric and ophthalmologic communities. Furthermore, many special education departments within universities also challenge the validity of coloured lenses as an effective treatment for the condition as outlined by the Macquarie University Special Education Centre.
In a joint statement, The American Academy of Ophthalmology, American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus and American Association of Certified Orthoptists firmly repudiated the use of lenses, stating that there was no scientific evidence supporting their use. The expense of such treatment is unwarranted and may divert resources from evidence-based treatment.
Critics claim that the symptoms of those with Scotopic Sensitivity Syndrome are related to already known visual perceptual and neurological disorders. According to a statement released by the American Optometric Association in 2004:
There is evidence that the underlying symptoms associated with specifically Meares Irlen Syndrome, are related to identifiable vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions, in many patients seeking help from coloured lenses. Furthermore, such conditions return to normal function when appropriately treated with lenses, prisms, or vision therapy. When patients exhibiting Meares Irlen Syndrome were treated with vision therapy, their symptoms were relieved. These patients were no longer classified as exhibiting this syndrome, and therefore did not demonstrate a need for the coloured overlays or tinted lenses.
As outlined by Hyatt, Stephenson and Carter (2009)
In 1990, the Journal of Learning Disabilities published a special issue that provided intensive coverage of Irlen lenses. In the preface to the issue, the editor in chief, Wiederholt, noted that each of the studies had serious theoretical, medical/physical, and methodological ﬂaws, but were published along with articles critiquing the studies to provide readers with an overview of the Irlen procedures as well as guidance for conducting quality research studies. He, along with Hoyt (1990), Parker (1990), and Solan (1990), noted that these initial studies by Blaskey et al. (1990), O’Connor, Sofo, Kendall, and Olsen (1990), and Robinson and Conway (1990) failed to support the treatment validity of colored overlays.
Critics assert that the term "scotopic sensitivity" is a misnomer given that the symptoms of "Scotopic Sensitivity Syndrome" reportedly occur during photopic conditions. The term "Scotopic Sensitivity" seems dubious, given that scotopic vision is the vision of the eye under low light conditions and as such vision is provided by rod cells on the retina, which have little or any role in colour vision, it does not make sense that a coloured lens or coloured overlay would have any impact upon "Scotopic Sensitivity Syndrome".
- "Joint statement—Learning disabilities, dyslexia, and vision". Pediatrics 124 (2): 837–44. August 2009. doi:10.1542/peds.2009-1445. PMID 19651597.
- Ritchie SJ, Della Sala S, McIntosh RD (October 2011). "Irlen colored overlays do not alleviate reading difficulties". Pediatrics 128 (4): e932–8. doi:10.1542/peds.2011-0314. PMID 21930551.
- Chouinard BD, Zhou CI, Hrybouski S, Kim ES, Cummine J (July 2012). "A functional neuroimaging case study of Meares-Irlen syndrome/visual stress (MISViS)". Brain Topogr 25 (3): 293–307. doi:10.1007/s10548-011-0212-z. PMID 22124535.
- "45th Annual Conference of the International Military Testing Association". Aaic.org.au. Retrieved 28 March 2014.
- Beasley IG, Davies LN (September 2012). "Susceptibility to pattern glare following stroke". J. Neurol. 259 (9): 1832–9. doi:10.1007/s00415-012-6418-5. PMC 3432783. PMID 22289968.
- Beasley IG, Davies LN (January 2013). "Visual stress symptoms secondary to stroke alleviated with spectral filters and precision tinted ophthalmic lenses: a case report". Clin Exp Optom 96 (1): 117–20. doi:10.1111/j.1444-0938.2012.00794.x. PMID 23282034.
- "Society for Colored Lens Prescribers".
- Irlens Lens Program – University of Newcastle, Australia
- American Academy of Pediatrics, 2009
- Cotton M, Evans K (1990). "A review of the use of Irlen (tinted) lenses". Aust N Z J Ophthalmol 18 (3): 307–12. doi:10.1111/j.1442-9071.1990.tb00625.x. PMID 2261178.
- Hyatt, KJ (2010). "Irlen Tinted Lenses and Overlays" (PDF). MUSEC Briefings (Macquarie University Special Education Centre) 22.
- Solan H, Richman J (1990). "Irlen lenses: a critical appraisal". J Am Optom Assoc 61 (10): 789–96. PMID 2136527.
- "The Use of Tinted Lenses and Colored Overlays for the Treatment of Dyslexia and Other Related Reading and Learning Disorders". Aoa.org. Retrieved 13 October 2009.
- "A Review of Three Controversial Educational Practices: Perceptual Motor Programs, Sensory Integration, and Tinted Lenses". Project MUSE - Education and Treatment of Children 32 (2): 313–342. 2009.
- Hoyt CS (December 1990). "Irlen lenses and reading difficulties". J Learn Disabil 23 (10): 624–6. doi:10.1177/002221949002301010. PMID 2280171.
- Parker RM (December 1990). "Power, control, and validity in research". J Learn Disabil 23 (10): 613–20. doi:10.1177/002221949002301008. PMID 2280169.
- Solan HA (December 1990). "An appraisal of the Irlen technique of correcting reading disorders using tinted overlays and tinted lenses". J Learn Disabil 23 (10): 621–3, 626. doi:10.1177/002221949002301009. PMID 2280170.
- Blaskey P, Scheiman M, Parisi M, Ciner EB, Gallaway M, Selznick R (December 1990). "The effectiveness of Irlen filters for improving reading performance: a pilot study". J Learn Disabil 23 (10): 604–12. doi:10.1177/002221949002301007. PMID 2280168.
- O'Connor PD, Sofo F, Kendall L, Olsen G (December 1990). "Reading disabilities and the effects of colored filters". J Learn Disabil 23 (10): 597–603, 620. doi:10.1177/002221949002301006. PMID 2280167.
- Robinson GL, Conway RN (December 1990). "The effects of Irlen colored lenses on students' specific reading skills and their perception of ability: a 12-month validity study". J Learn Disabil 23 (10): 589–96. doi:10.1177/002221949002301005. PMID 2280166.
- Wilkins, Arnold J. (2003). Reading through color: how colored filters can reduce reading difficulty, eye strain, and headaches. Chichester: John Wiley & Sons. ISBN 0-470-85116-3. OCLC 78883050.
- "A new light on reading trouble". Irlen Centre Canada.
- Going through the looking glass, BBC News, 3 June 2007.
- Irlen Institute, Colored Lenses, Colored Overlays, Diagnosticians, Screeners
- "Learning difficulties – A Discussion of the various eye treatment programs for Learning Difficulties".
- Research in use of overlays
- University of Essex and Institute of Optometry – Visual Stress and its treatment