The Use of Tinted Lenses and Colored Overlays for the Treatment of Dyslexia and Other Related Reading and Learning Disorders
Over the past two decades the use of tinted lenses and colored overlays to improve reading comfort and performance has been presented in both the popular media and professional literature. With increasing frequency, patients and parents consult optometrists about the value of colored overlays and tinted lenses. Meares1 and later Irlen2 described a syndrome of visual symptoms and distortion that can be alleviated with colored filters. This syndrome has been referred to as "scotopic sensitivity syndrome" or the Irlen Syndrome.3 Colored overlays and tinted lenses are purported to improve reading ability and visual perception, increase sustained reading time, and eliminate symptoms associated with reading such as light sensitivity, eyestrain, headaches, blurring of print, loss of place, and watery eyes.
A comprehensive review of the available scientific literature regarding the effectiveness of tinted lenses or filters revealed the following:
There is evidence that the underlying symptoms associated with the Irlen Syndrome are related to identifiable vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions, in many patients seeking help from colored lenses.4-7 Furthermore, such conditions return to normal function when appropriately treated with lenses, prisms, or vision therapy. When patients exhibiting the 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 colored overlays or tinted lenses.4
Most investigators have not controlled for the presence of vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions. In most cases, researchers have simply assumed that a history of a previous eye examination ruled out any significant vision problem.8-14 Others have developed a protocol to screen for vision problems but have not included an adequate battery of tests to eliminate common accommodative, binocular, and ocular motor dysfunctions.3, 15-19
The results of prospective, controlled research on the effectiveness of tinted lenses or colored overlays vary. One randomized, controlled trial demonstrated that children with reading difficulties, who were prescribed filters based on colored overlays, experienced reduced symptoms of asthenopia.15 While this study suggests the color may need to be individually and precisely prescribed, another study demonstrated significantly improved eye movements among reading disabled children when reading through blue filters.20 Other researchers failed to find improvement in comprehension scores in readers using tinted lenses.4
Results of testing utilized to determine the most appropriate color are not repeatable.21, 22 There are numerous variables within the individual and the environment (such as differences in lighting between the home and various classrooms) that can influence the effectiveness of assigned overlays. It has been reported that up to twenty-five percent of the time, children who receive tinted lenses need to have their tints adjusted within the first year.23
The effect of spectral filters and colored overlays is not solely a placebo.15 Colored overlays and tinted lenses are not cures for dyslexia, but may be useful reading aids for some individuals with reading difficulty.24
The underlying physiological mechanism for the Irlen Syndrome is still not known. While some argue that a magnocellular deficit exists in these individuals,25-29 others suggest the problem is pattern glare.30, 31
There is lack of agreement about the best way to evaluate patients for the presence of the Irlen Syndrome. Some suggest the use of the Irlen 2-part evaluation system,32 while others promote the use of the Intuitive Colorimeter.33 Both systems require additional research.
Visual processing is a fundamental part of the reading process.34 Future research must address the issue of underlying vision anomalies, sub‑typing of reading disabilities and the differential response to different treatments. Controlled clinical research will allow reading and learning disabled individuals, their parents, and the professionals who work with them, to better evaluate the effectiveness of available treatments for each individual.
Therefore, it is the position of the American Optometric Association that:
1. Undetected vision problems may be a factor in individuals who exhibit the symptoms of the Irlen Syndrome. A comprehensive vision examination (NDVE) with particular emphasis on accommodation, binocular vision, and ocular motor function is recommended for all individuals experiencing reading or learning difficulties, as well as those showing signs and symptoms of visual efficiency problems.
2. The American Optometric Association encourages further research to investigate the effect that specifically tinted lenses and colored overlays have on visual function related to reading performance.
3. Vision problems are a frequent factor in reading difficulities. Ignoring the role of vision or inadequately evaluating the vision of individuals with reading problems is a disservice which may prevent the person from receiving appropriate care.
This publication was formulated by the American Optometric Association’s Binocular Vision Working Group. The following individuals are acknowledged for their contributions:
Gary J. Williams, O.D., Chair
Gregory Kitchener, O.D.
Leonard J. Press, O.D.
Mitchell M. Scheiman, O.D.
Glen T. Steele, O.D.
Approved by: American Optometric Association, April 2004
Meares O. Figure/ground, brightness contrast, and reading disabilities. Visible Language, 1980;14: 13-29.
Irlen H. Successful treatment of learning difficulties. in 91st Annual Convention of the American Psychological Association. August 1983. Anaheim, CA.
Evans BJ, et al., A preliminary investigation into the aetiology of Meares-Irlen syndrome. Ophthal Physiol Opt 1996;16:286-296.
Blaskey P, et al. The effectiveness of Irlen filters for improving reading performance: A pilot study. J Learning Dis 1990;23: 604-612.
Scheiman M., et al., Vision characteristics of individuals identified as Irlen Filter candidates. J Am Optom Assoc, 1990; 61:600-605.
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Whiting PR. Improvement in reading and other skills using Irlen coloured lenses. Aust J Remed Educ 1988;20:13-15.
Clayton P. The Irlen lens: scotopic sensitivity. Optician, 1987. 194: p. 22-25.
Robinson GL, Conway RNF. The effects of Irlen colored lenses on students' specific reading skills and their perception of ability: a 12-month validity study. J Learning Dis, 1990; 23: 621-626.
O'Connor PD, Sofo F, Kendal L. Reading disabilities and the effects of colored filters. J Learning Dis 1990; 23:597-603.
Wilkins AJ, et al. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthal Physiol Opt 1994;14:365-370.
Evans BJ, et al., Optometric correlates of Meares-Irlen Syndrome: a matched group study. Ophthal Physiol Opt 1995;15:481-487.
Scott L, et al.. Coloured overlays in schools: orthoptic and optometric findings. Ophthal Physiol Opt 2002; 22:156-165.
Evans BJ, Joseph F. The effect of coloured filters on the rate of reading in an adult student population. Ophthal Physiol Opt 2002; 22:535-545.
Spafford CS, et al.. Contrast sensitivity differences between proficient and disabled readers using colored lenses. J Learning Dis, 1995;28:240-252.
Solan HA, et al.. Eye movement efficiency in normal and reading disabled elementary school children: effects of varying luminance and wavelength. J Am Optom Assoc 1998;. 69: 455-464.
Solan HA, Richman J. Irlen Lenses: A critical appraisal. J Am Optom Assoc 1990; 61: 789-796.
Woerz M, Maples WC. Test-Retest Reliability of Colored Filter Testing. J Learn Disabil 1997; 30: 214-221.
Stone R. The light barrier: understanding the mystery of Irlen syndrome and light-based reading difficulties. New York: St. Martin's Press, 2003.
Wilkins AJ. Overlays for classroom and optometric use. Ophthal Physiol Opt 1993;14: 97-99.
Livingston MS, et al. Physiological and anatomical evidence for a magnocellular defect in developmental dyslexia. Proc Natl Acad Sci USA, 1991; 88:7943-7947.
Solan HA, et al., Transient and sustained processing: effects of varying luminance and wavelength on reading comprehension. J Am Optom Assoc 1997;68:503-510.
Solan HA, et al., Coherent motion threshold measurements for M-cell deficit differ for above- and below-average readers. Optometry 2003; 74:727-734.
Williams MC, LeCluyse K. Perceptual consequences of a temporal processing deficit in reading disabled children. J Am Optom Assoc 1990; 61:111-121.
Lehmkuhle S, et al. A defective visual pathway in children with reading disability. N Engl J Med 1993; 328: 989-996.
Evans BJ, et al. Effect of pattern glare and colored overlays on a simulated-reading task in dyslexics and normal readers. Optom Vis Sci 1994; 71: 619-628.
Wilkins AJ, Milroy R, Nimmo-Smith, I. Preliminary observations concerning treatment of visual discomfort and associated perceptual distortion. Ophthal Physiol Opt 1992;12:257-263.
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