The use of coloured lenses or overlays to ameliorate reading difficulties “cannot be endorsed,” a new paper has concluded.
Writing in the College of Optometrists’ research journal, Ophthalmic and Physiological Optics, a University of Bradford team, led by Professor Brendan Barrett, states that any benefits reported by individuals in clinical settings are likely to be the result of placebo, practice or so-called ‘Hawthorne’ effects.
Setting out the motivation for the paper – which is described by the authors as a systematic review of the literature and examination of the quality of the evidence – the researchers explain that, “there are many anecdotal claims and research reports that coloured lenses and overlays improve reading performance.”
The effect of coloured overlays and lenses on reading paper reviewed literature concerning the effect of coloured lenses or overlays on reading performance, focusing on evidence under four separate systems including the ‘intuitive’ system, classifying each published item using the Cochrane Risk of Bias tool.
Presenting the results, the authors discuss the strengths and shortcomings of the published literature. They acknowledge the difficulties associated with conducting trials of this type, and offer suggestions about how future trials might be conducted.
The authors state: “The majority of studies are subject to ‘high’ or ‘uncertain’ risk of bias in one or more key aspects of study design or outcome, with studies at lower risk from bias providing less support for the benefit of coloured lenses/overlays on reading ability.”
The team add: “While many studies report improvements with coloured lenses, the effect size is generally small and/or similar to the improvement found with a placebo condition.”
Alongside the paper, an overview of the placebo effect and a discussion of some of the implications for practitioners are provided by Ophthalmic and Physiological Optics’ editor-in-chief, Professor David Elliott.
In a press statement, the College of Optometrists said that it regularly reviews its clinical guidance, and such reviews are based on the best available evidence where possible. The College explained: “The full implications of this latest coloured filters research will be factored into the next review (taking place over the next year) in order to ensure that we continue to help members to deliver the best possible care for patients.”
OT understands that over 500 community optometry practices and hospital and university clinics use the intuitive colorimetry (IC) in the UK. Having contacted the College to ask what advice it would give to practitioners about their continued use of IC and other overlay products, Jo Mullin, the College’s Director of Policy and Strategy, told OT: “The College's position is that its members should use their professional judgement, informed by the best available evidence, in deciding whether they offer IC assessments and subsequent treatment or intervention. This has not changed. It is important that optometrists who do offer IC ensure that they are up to date with all the current evidence, in particular this review, which raises significant questions about its efficacy and the limited availability of high quality research. Optometrists should ensure their patients are adequately informed about the procedure and the current evidence relating to it. This enables the patient to give informed consent before proceeding with the test and/or intervention.”
Commenting on the timescale for a clinical review, the College added: “There are no plans to bring the review of the College’s guidance for professional practice forward. The College would only bring forward a planned review, or issue interim updates or changes to guidance, in a situation when new evidence pointed to an area of practice, treatment or intervention carrying a previously unknown risk to the well being of patients. The College’s revised guidance for professional practice is expected to be published in the autumn of 2017.”
Alternative review finds support for coloured filters
Responding to the publication of the report, a spokesperson for Cerium Visual Technologies told OT: "We manufacture and distribute the intuitive colorimeter under license from the Medical Research Council.
"Following extensive research during development, the instrument is now used by hundreds of optical practices, both in the UK and overseas, and is used clinically in every university department of optometry within the UK. Many thousands of patients have been helped by colorimetry, and the countless accounts of the life-changing benefits of precision tinted lenses are in stark contrast to the findings of this review.
"Cerium Visual Technologies continues to support and promote the intuitive colorimeter with unequivocal confidence that many more individuals will be helped in future."
Speaking to OT about the review, director of research at the Institute of Optometry, Professor Bruce Evans, said: "The authors of this review have previously expressed their sceptical views on the existence and treatment of visual stress (VS). On reading the review I realised that the authors had started with the conviction that VS does not exist and had looked for evidence to support this view. I think that their stance was “what can we find to show we are right?” with a refusal to contemplate the alternative, “what if we are wrong?”"
Professor Evans confirmed that he will be writing to the editor of Ophthalmic and Physiological Optics with more detailed comments. "Suffice it to say at this stage that the authors of this review apply a high level of critical appraisal of studies with positive results and take a “light touch” when dealing with studies with negative findings," he added. "There is a great deal of research in this field that attempts to investigate VS in people who don’t have VS. This needs to be considered in any review."
Professor Evans closed: "Professor Peter Allen and I have also written a systematic review that has been accepted for publication in the peer-reviewed open access Journal of Optometry. By reading both reviews I think that interested practitioners will gain a balanced insight into this fascinating topic.
"The findings of our systematic review support the existence of VS. We agree with the authors that although this is a difficult area to research, more rigorous research is required. I very much hope that the continuing controversy will lead to more research and that this will help more of those children who struggle to see the page when trying to read."