Fact or fiction?
Professor Chris Hammond discusses the evidence around blue light
Is blue light harmful? Professor Chris Hammond addressed the conundrum that has been on many practitioners’ minds since Boots Opticians was fined £40,000 in May during his presentation Blue light: Good, bad and ugly at the Royal Society of Medicine in London (12 October).
In short, Professor Hammond told delegates that the answer is ‘no.’
“I think we can safely say that blue light is not harming the majority of our eyes,” he emphasised.
Professor Hammond began his presentation by highlighting that blue turquoise light has positive effects.
It stimulates the photosensitive retinal ganglion cells, stimulates pupillary reflex and controls the circadian cycle.
Switch off before sleep
Because screens produce this type of blue light, people have been advised to avoid looking at their phone or tablet before going to sleep, Professor Hammond mentioned.
“We’re all aware of the general advice that we should avoid looking at screens before bed in order to improve sleep hygiene,” he shared.
The focus of concern around blue light has centred on blue ultraviolet light, which is found in significant levels in LED lights.
Professor Hammond observed that research has shown cell cultures exposed to ultraviolet light show oxidative damage, while studies of albino rats have shown retinal stress.
However, the question of whether blue light accelerates ageing and increases the risk of age-related macular degeneration was answered in the negative by the European Eye Study.
This research was a comprehensive assessment of 5473 at seven sites who were followed over their lifetime from the age of 14.
“There was no association between AMD and blue light,” Professor Hammond highlighted.
He observed that when a meta-analysis of 14 studies was adjusted for publication bias, there was also no link between blue light and AMD.
“I think largely we can put that [question] to bed,” Professor Hammond stressed.
Protective effect of light
The St Thomas’ Hospital consultant shared that there is evidence that light protects people from developing myopia.
A UK study of 1500 identical twins included 60 sets of twins where one twin was myopic while the other was not.
Professor Hammond outlined that the common factor in these sets of twins was that the twin without myopia spent more time outdoors than the twin who is short-sighted.
“Light appears to be protective,” he added.
He highlighted that while there were many products that claimed to protect people from blue light, the damage from light is proportionate to its intensity.
Blue light from screens is much weaker than the blue light people are exposed to outdoors, he shared.
“There is really absolutely no evidence that blue light is harming our eyes,” Professor Hammond concluded.
A contentious issue
AOP clinical director, Dr Peter Hampson, told OT that increasing amounts of time spent on computers, devices and phones had caused many people to worry about how technology could be affecting their health.
“Screen use, and specifically blue light, has been the source of much debate when it comes to eye health,” he observed.
Research from the AOP’s Voice of Optometry panel shows that more than 80% of optometrists have seen patients in the past month who have concerns about screen use damaging their eyes.
“This is why the AOP recently set out our position which weighs up the evidence on blue visible light and confirms there is none to support that it has a detrimental impact on eye health,” Dr Hampson highlighted.
“However, we do know there is some evidence to suggest that using screens close to bed may contribute to poorer sleep,” he added.
The AOP has guidance around this in the form of a patient advice leaflet on screen time.
Dr Hampson emphasised that the AOP will continue to monitor research on the topic.
“Should the evidence base shift either way, we will update our position to reflect this,” he concluded.