Scandinavian Journal of Occupational Therapy. 2015; Early Online, 1–2
LETTER TO THE EDITOR
Using coloured filters to reduce the symptoms of visual stress in children with reading delay
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PHILIP G. GRIFFITHS Ophthalmology, St Bernards Hospital, Harbour Views Road, Gibraltar
Abstract The way citation distortion can create unfounded authority in a subject area is exemplified in the paper “Coloured filters to reduce the symptoms of visual stress in children with reading delay”, published early online in the Scandinavian Journal of Occupational Therapy. The diagnostic criteria for visual stress remain unclear, for which reason the prevalence figures should be viewed with scepticism. Randomized controlled trials with placebo control groups consistently show improvements in experimental and control lenses. This letter is a critical review of the evidence cited in the introduction to the paper. In the light of this the most likely explanation for their results is the placebo effect.
Key words: visual stress, dyslexia, coloured filters
I read with interest the early online publication “Coloured filters to reduce the symptoms of visual stress in children with reading delay” (1). In the introduction it is stated that visual stress occurs in 5–20% of the population. It is surprising that the only citation to support this assertion is to a charity website. Because the diagnosis of visual stress depends on vague and subjective symptoms and because there are no validated diagnostic tests, research on the prevalence of visual stress needs to be viewed with scepticism. In an ideal study the assessors would be blinded to the status of the subjects as poor readers or normal readers. The only such study diagnosed approximately 50% of normal readers and poor readers (2). Another study published in 2005 using the Wilkins Rate of Reading Test (WRRT) did find a higher prevalence of visual stress in subjects with dyslexia but this did not reach statistical significance and furthermore it was not a masked study and thus at risk of bias (3). The relationship between so-called visual stress and reading difficulties is problematic and proponents have to explain why the overwhelming majority of people with so-called visual stress do not have reading difficulties.
Elsewhere in the introduction the authors state that “this type on intervention has been found to ease the discomfort experienced and improve reading accuracy”, citing two publications in support of this claim (4,5). However, ignoring any issues of “cherry picking”, even these papers do not support these claims. The randomized controlled trial by Wilkins et al. was hampered by a high rate of dropout and showed no improvement in reading speed, accuracy, or comprehension compared with placebo in 45 out of 68 subjects. There was a small difference in terms of symptom diaries; however, data were only available for 36 out of 68 subjects. The study also contained conflicting data. When asked at the end of the study, 26 subjects preferred the control filter and 24 the experimental filter. The study by Robinson and Foreman published in 1999 showed that all groups improved over the study period but there was not a significant difference between experimental filter and blue or placebo filter. High claims of subjective benefit were noted in all groups, suggesting an effective placebo effect (4). The authors also fail to reference other negative randomized controlled trials (6,7).
Correspondence: Philip G. Griffiths, Consultant Ophthalmologist, Gibraltar Health Authority, St Bernards Road, Harbour Views Road, GX11 1AA, Gibraltar. E-mail: philip.griffi
[email protected] This Letter has a published response - Response to the letter by Priscilla Harries (DOI: 10.3109/11038128.2015.1033457). (Received 11 February 2015; accepted 20 March 2015) ISSN 1103-8128 print/ISSN 1651-2014 online Ó 2015 Informa Healthcare DOI: 10.3109/11038128.2015.1033456
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Letter to the Editor
In citing the paper by Bouldoukian the authors do not mention that the very modest increase in reading speed was not for naturalistic text but for the jumbled words of the Wilkins Rate of Reading Test (WRRT) and the study did not include “attentional” controls (8). Other studies have shown that increased reading speed of the WRRT produced with coloured overlays is neither sustained nor matched by improvements in reading naturalistic text (9). It is stated that the American Academy of Pediatrics does not advocate the use of colour. However, this was a combined statement from the American Academy for Pediatrics, Council for Children with Disabilities, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and the American Association of Certified Orthoptists (10) and thus carries rather more weight. Although the authors acknowledge that the use of colour to treat the symptoms of visual stress is a contentious issue they fail to reference the only two systematic reviews on the subject, neither of which supports the use of colour to treat visual stress when it coexists with dyslexia (11,12). The way citation distortion can create unfounded authority has been well studied (13) and is exemplified in the introduction section of this paper. In the methods section the authors state “it was ethically unjustified to use a control group as no benefit had been achieved with placebo filters”. The authors cite one of their own publications in support of this (14). However, this study did not even contain a placebo control group. Randomized controlled trials consistently show that placebo control groups do just as well as those with the experimental lens (4-6). Given that studies consistently show improvements in both experimental and placebo lens groups, the most likely explanation of the results reported in the study is the placebo effect. Declaration of interest: The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.
References 1. Harries P, Hall R, Ray N, Stein J. Using coloured filters to reduce the symptoms of visual stress in children with reading delay. Scand J Occup Ther 2015;22:153–60. 2. Kruk R, Sumbler K, Willows D. Visual processing characteristics of children with Meares-Irlen syndrome. Ophthalmic Physiol Opt 2008;28:35–46. 3. Kriss I, Evans BJW. The relationship between dyslexia and Meares-Irlen Syndrome. J Res Read 2005;28:350–64. 4. Robinson GL, Foreman PJ. 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. Percept Mot Skills 1999;89:83–113. 5. Wilkins AJ, Evans BJ, Brown JA, Busby AE, Wingfield AE, Jeanes RJ, et al. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthalmic Physiol Opt 1994;14:365–70. 6. Ritchie SJ, Della Sala S, McIntosh RD. Irlen colored overlays do not alleviate reading difficulties. Pediatrics 2011;128:e932– 8. 7. Mitchell C, Mansfield D, Rautenbach S. Coloured filters and reading accuracy, comprehension and rate: A placebocontrolled study. Percept Mot Skills 2008;106:517–32. 8. Bouldoukian J, Wilkins AJ, Evans BJW. Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Ophthalmic Physiol Opt 2002;22:55–60. 9. Henderson LM, Tsogka N, Snowling MJ. Questioning the benefits that coloured overlays can have for reading in students with and without dyslexia: Journal of Research in Special Educational Needs. J Res Spec Educ Needs 2013;13:57–65. 10. Handler SM, Fierson WM. Section on Ophthalmology. Learning disabilities, dyslexia, and vision. Pediatrics 2011; 127:e818–56. 11. Albon E, Adi Y, Hyde C. West Midlands Health Technology Assessment Collaboration. The effectiveness and costeffectiveness of coloured filters for reading disability: A systematic review. Studley: West Midlands Health Technology Assessment Collaboration, Department of Public Health and Epidemiology, University of Birmingham; 2008. 12. Galuschka K, Ise E, Krick K, Schulte-Körne G. Effectiveness of treatment approaches for children and adolescents with reading disabilities: a meta-analysis of randomized controlled trials. Lidzba K, editor PLoS One 2014;9:e89900. 13. Greenberg SA. How citation distortions create unfounded authority: Analysis of a citation network. BMJ 2009;339: b2680. 14. Hall R, Ray N, Harries P, Stein J. A comparison of twocoloured filter systems for treating visual reading difficulties. Disabil Rehabil 2013;35:2221–6.
