The College of Optometrists’ research journal, Ophthalmic and Physiological Optics, has published a systematic review about the effect of coloured overlays and lenses on reading, by Professor Brendan Barrett at Bradford University and colleagues.
It found that the majority of studies in this area are subject to high or uncertain risk of bias in one or more key aspects of study design or outcome, and that the collected evidence suggests that placebo and observer (‘Hawthorne’) effects are likely to be responsible for any improvement. An overview of the placebo effect and a discussion of some of the implications for practitioners are provided by OPO’s editor-in-chief, Professor David Elliott.
The College regularly reviews its clinical guidance, and such reviews are based on the best available evidence where possible. The full implications of this latest coloured filters research will be factored into the next review (taking place over the next year).