Review finds placebo effect of coloured overlays

Placebo and observer ‘Hawthorne’ effects were likely to be responsible for any improvement coloured overlays and lenses have on reading, according to a review in The College of Optometrists research journal, Ophthalmic and Physiological Optics.

It has published a systematic review on the effect, by Professor Brendan Barrett at Bradford University and colleagues, which found that the majority of studies in this area were ‘subject to high or uncertain risk of bias in one or more key aspects of study design or outcome’.

‘The full implications of this latest coloured filters research will be factored into the next review [in 2017] in order to ensure that we continue to help members to deliver the best possible care for patients,’ a statement added.