Articles

The article submitted by Peter Chaban on Irlen Filters and Learning Disabilities does not, in my opinion, provide a balanced view on the topic. In [the] review of Irlen precision coloured filters, the author concludes that the case for the use of filters is not based on valid scientific research. However, there are errors in the reporting of results and little attention is paid to many published and well controlled studies, which clearly identify that coloured filters can make positive changes to reading ability.

The article accurately reports the origins of Scotopic Sensitivity Syndrome and on semantic problems with the use of the term Scotopic Sensitivity. However, the summary of research begins by quoting the concerns of authors who published reviews over 10 years ago. Some of these earlier studies did have methodological problems, but there have been a large number of controlled studies since that time which have been published in peer reviewed journals. These journals have reviewers with expertise in their respective fields and are unlikely to recommend the publication of studies with serious methodological flaws. One researcher cited is Bruce Evans (Evans & Drasdo, 1991) who criticised the literature at that time for “unscientific testing”. However, since that time Evans has been a contributing author in a number of studies on coloured filters which are well-controlled and have had positive results. Only one of these studies has been mentioned in this review.

The report, quite correctly, devotes considerable time to the important issue of placebo effects, which occur when a person may respond to a “treatment” because they believe or hope it will help when it actually has no scientific benefit. The author correctly states that when working with coloured filters, controlling for placebo effects requires the inclusion of filters which have similar colours to the precision tints, but outside the effective colour range. The author is also accurate in identifying the study by Wilkins and colleagues (1994) as the first published double-blind placebo controlled study. However, the reporting of the double-blind placebo controlled study by Robinson and Foreman (1999) has some critical errors. This study included a control group of students with no reading disabilities and no filters, as well as three experimental groups given placebo, blue and precision filters. The placebo tints were of similar colour to the precision tints, but outside the effective colour range. The experimental groups, given the blue and placebo filters, used these for a 3 to 4 month period and then “crossed over” to their precision filters. Reading level was assessed prior to the study, at the time of “crossover”, four months later, and at a further 12 month interval.

The first error in reporting this study is the statement that it was of four month’s duration. It is true that both the blue and placebo filters were used for four months and the two groups wearing these filters improved, indicating a possible placebo effect as expected. However, after four months the blue and placebo groups crossed over to their precision tints. At this “crossover” stage, there was a significant increase in reading comprehension for subjects when they crossed from blue and placebo filters to precision Irlen filters, and a significant increase in rate of reading when subjects crossed over from placebo to precision Irlen filters. In other words, while improvements occurred regardless of filter type in the first 3 to 4 months, there were significantly greater improvements when they crossed over from blue and placebo to Irlen precision filters. These improvements in Irlen precision filters were then maintained for the next 15 to 16 months of the study.

The “Synopsis of Research” for this study on the Irlen web site, accurately reported gains for all 3 study groups of 2 to 3 years, compared to the control, but did not mention the “crossover” to precision filters at 3 to 4 months. This synopsis could give the impression that improvements occurred in all filters and the synopsis is used by the author to state that “improvements occurred regardless of filter type and that precision tints were not more effective than placebo tints”. The author cites this synopsis as an example of “ambiguity and unreliability of second-hand accounts of research findings”, but is guilty of the same problem in also not reporting the “crossover” stage from blue and placebo filters to precision filters when reviewing the article. I can only assume that either the author did not read the study in detail or chose to omit this critical feature of the study. In addition to errors in reporting the Robinson and Foreman (1999) study, the report does not provide detailed information about the large number of more recent controlled studies. The only acknowledgment of these studies is a caution about some which use the “Rate of Reading” test. The author omits to mention that many of these studies were conducted under carefully controlled conditions, with large numbers of students and with long-term evaluation. The author also states that there are serious methodological concerns with most of these studies, but does not provide any examples of these concerns. The author also does not acknowledge that most of these studies have been published in peer reviewed journals, and the reviewers for these journals usually have international standing in their fields. These reviewers and the journals they represent are not likely to publish studies with serious methodological flaws as mentioned previously. If the review of studies is widened to include investigations which support the use of coloured overlays, as well as Irlen lenses, there have been numerous controlled studies published in peer reviewed journals. Recent studies have reported improvements with coloured overlays or with coloured computer monitors (see Croyle, 1998; Jeanes, Busby, Martin, Lewis, Stevenson, Pointon et al., 2002; Tyrrell, Holland, Dennis, & Wilkins, 1995; Wilkins & Lewis, 1999; Wilkins, Lewis, Smith, & Rowland, 2001; Williams, Le Cluyse, & Littell, 1996). This is in addition to studies reporting improvements in eye strain, headaches and reading when using precision coloured lenses (see Chronicle & Wilkins, 1991; Evans, Patel & Wilkins, in press; Good, Taylor, & Mortimer, 1991; Harris & MacRow-Hill, 1999; Irvine & Irvine, 1997; Lightstone, Lightstone, & Wilkins, 1999; Robinson & Conway, 2000; Robinson & Foreman, 1999a, b; Solan, Brannan, Ficarra, & Byne, 1997; Solan, Ficarra, Brannan, & Rucker, 1998). A number of these studies have used placebo controls (see Bouldoukian, Wilkins, & Evans, 2002; Jeanes et al., 1997; Robinson & Foreman, 1999a, Wilkins, Evans, Brown, Busby, Wingfield, Jeanes, & Bald, 1994; Wilkins & Lewis, 1999).

Of the investigations cited above, the paper by Wilkins et al. (2001) is one that the author cautioned against because it only uses a “reading subskills” measure (The Rate of Reading Test). However, this paper describes 3 studies which involved large numbers of students and included assessment using white paper, a random coloured overlay and a preferred coloured overlay. All 3 studies found an immediate and significant improvement in rate of reading using the preferred coloured overlay. In the third study, there was also a significant improvement in rate of reading for those using the preferred coloured overlay 8 months later. The study by Bouldoukian et al. (2002) used a number of measures to ensure that a strong placebo effect was associated with the control (ultraviolet blocking) overlay, by placing it in a specially marked frame and describing it as a new filter, specially designed to help reading problems. When asked which overlay they preferred, subjects were not significantly more likely to prefer their chosen overlay to the control filter, but reading was significantly faster with the chosen overlay. One final example of the range of research coming from different countries and disciplines is the investigation by Solan et al. (1997) from the State College of Optometry, New York. This study required children to read a series of standardised 300 word passages using no filter, a light grey filter, a dark grey filter and a blue filter. The comprehension scores for poor readers compared to good readers were significantly better using coloured filters.

I do not feel it is appropriate, in the important area of literacy, to conduct a numbers war by counting the positive and negative studies. I do, however, feel that professionals who report to the public have a responsibility to report accurately and to report on all the research available. I am concerned that this report has been remiss on both counts.

Dr. Greg Robinson

REFERENCE LIST

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