Jeanes R, Busby A, Martin J, Lewis E, Stevenson N, Pointon D, et al. Prolonged use of coloured overlays for classroom reading. Br J Psychol. 1997 Nov;88(4):541–8.
You can download this paper from Arnold Wilkins webpage here
The paper starts with some background information about Intuitive Overlays vs Irlen Overlays and the authors make their point by plotting the chromaticity coordinates of Irlen overlays and Intuitive overlays. However, they exaggerate the difference between the two systems by plotting both the x and y coordinates on different scales. See the figure below. In my opinion, this is poor practice in scientific reporting.
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| The authors exaggerate the difference between Irlen and Intuitive overlays by plotting the chromaticity coordinates on different scales and with different symbols. This is poor practice in representing data and it is noteworthy that one of the authors has a financial interest in Intuitive Overlays; the system that benefits from this distorted representation. |
Prevalence of 'visual stress'
In the first part of the paper, the authors estimate the prevalence of visual stress in 93 children attending a primary school and 59 children attending the first year of secondary school. When asked to look at random letters (not naturalistic text) through overlays 51% of the former group and 54% of the latter chose an overlay to ameliorate perceptual distortions. When the group was reassessed at two months 35% of the primary school group said they were still wearing lenses and wished to continue (note this is based on self-report without independent verification). Similarly, 36% or secondary school children were still using and wished to continue with overlays. By ten months this had dropped even further so that 14% of the primary school group were still using overlays or glasses and only 5% of the secondary school group. By the criterion of voluntary sustained use, the prevalence of visual stress in a mixed ability group of children should be between 5-14%. What is remarkable about this and other papers looking at coloured overlays and lenses to treat visual stress is the astonishing rate of attrition over time.
In the first part of the paper, the authors estimate the prevalence of visual stress in 93 children attending a primary school and 59 children attending the first year of secondary school. When asked to look at random letters (not naturalistic text) through overlays 51% of the former group and 54% of the latter chose an overlay to ameliorate perceptual distortions. When the group was reassessed at two months 35% of the primary school group said they were still wearing lenses and wished to continue (note this is based on self-report without independent verification). Similarly, 36% or secondary school children were still using and wished to continue with overlays. By ten months this had dropped even further so that 14% of the primary school group were still using overlays or glasses and only 5% of the secondary school group. By the criterion of voluntary sustained use, the prevalence of visual stress in a mixed ability group of children should be between 5-14%. What is remarkable about this and other papers looking at coloured overlays and lenses to treat visual stress is the astonishing rate of attrition over time.
Clinical trials
The paper also contains two trials of sorts. Both are at high risk of bias and use a non-standardised reading test of unknown relevance to real world reading. The Wilkins Rates of Reading Test (WRRT).
Those who continued using overlays for ten months were tested with and without overlays. There was no placebo group and the study was not masked. The authors found a small difference in words per minute on the WRRT.
However, another part of the paper describes a small study which did have a placebo control overlays of a complementary colour. This time there was no statistically significant difference between the two groups.
Conclusion
Overall some questionable reporting and what appears to be a posthoc data trawl. The data does not provide compelling evidence for the treatment of visual stress with colour.
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