August 18, 2023

expert reaction to Cochrane review on blue-light filtering spectacles for eye strain, eye health and sleep quality

A review published in Cochrane Database of Systematic Reviews looks at the use of blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults.

Prof Andrew Przybylski, Associate Professor and Director of Research at the Oxford Internet Institute, University of Oxford, said:

Does the press release accurately reflect the science?

“Yes, the press release tracks closely with the findings as they’re described in the paper.”

Is this good quality research?  Are the conclusions backed up by solid data?

“This research applies a gold-standard review approach to ask an interesting question of an idea that is widely believed but poorly evidenced.”

How does this work fit with the existing evidence?

“The idea that blue light from devices negatively impacts health and sleep is popular but not well evidenced. It is interesting and important that the researchers examined whether glasses sold to address the putative negative effects of blue light from screens. They rightly note that few studies that claim benefits.”

Have the authors accounted for confounders? 

“The authors and reviewers do a good job identifying potential confounding factors and are careful to consider the role that aspects of the studies they examined, for example, the populations and duration of the trials. These intervening factors have more to do with the designs of the studies under analysis than the review format itself. A greater number of studies could have provided a richer set of confounders the review could have considered but given the pattern of results reported I expect this would have required much more resourcing than the hypothesis deserves.”

Are there important limitations to be aware of?

“The overall number of studies and clinical trials purporting to examine the effectiveness of blue light blocking glasses are low and have been fairly characterised by this review as very low quality. The authors report about 2 in 3 studies were not included in a clinical trial registry and less than half reported basic statistics required to calibrate an effective trial. This could be a case of garbage in, garbage out. I could imagine that glasses are very effective for some other health reason, but the studies are so poorly designed they cannot detect whether this is the case.”

What are the implications in the real world?

“I thought this evidence base was not reliable, but this review is fairly damning. It provides the public an opportunity to pause and ask themselves if they really should be changing their behaviour or buying things to address what they fear are problems of the digital age. It would be a good thing that people apply the same wariness they have towards technology to the research that confirms their fears and to those who sell quick-fix solutions.”

Is there any over-speculation?

“This is a fairly circumspect piece of research, and I would like to see this approach applied to other questions of how technology, health, and solutions are potentially linked.”

Prof Russell Foster, Professor of Circadian Neuroscience, University of Oxford, said:

“This is a very timely review of the currently available data. Blue-light filtering lenses are being used by individuals around the world based upon claims that they improve sleep quality, reduce eye strain and protect the retina from light-induced damage. Yet the evidence for such statements is at best weak, and at worst non-existent. However, the team make the very important point that the studies undertaken to date have significant methodological limitations, including – group sizes, length of evaluation, the spectrum and levels of the light reaching the eye, and the measurements of impact. As a result, although the available data indicate that blue-light filtering lenses are not effective, we need better studies to make this statement definitive.”

‘Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults’ by Sumeer Singh et al. was published in Cochrane Database of Systematic Reviews at 00:01 UK time Friday 18 August 2023.

DOI: 10.1002/14651858.CD013244.pub2.

Declared interests

Prof Andrew Przybylski: I do not believe I have any interests give rise to a conflict with my role as an expert in this story. My research is funded in full by the ESRC, UKRI, and the Huo Family Foundation.

For all other experts, no reply to our request for DOIs was received.