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Jul 22, 2023

Blue

Blue-light filtering glasses may not reduce eyestrain associated with computer use, and their effect on improving sleep quality and retinal health is unclear, a review published Thursday says. “Our

Blue-light filtering glasses may not reduce eyestrain associated with computer use, and their effect on improving sleep quality and retinal health is unclear, a review published Thursday says.

“Our review doesn’t support using a blue-light filtering lens if you’re a healthy adult for the purpose of reducing eyestrain with computer use,” said Laura Downie, the review’s senior author and an associate professor of optometry and vision sciences at the University of Melbourne.

The review of 17 randomized controlled trials, published in the Cochrane Database of Systematic Reviews, confirms what eye-care professionals have said for some time about the popular glasses.

“There’s really been no evidence that blue-light blocking glasses have any health benefits or even ocular benefits when it comes to eyes,” said Rahul Khurana, a vitreoretinal surgeon and spokesperson for the American Academy of Ophthalmology who was not involved in the study.

Eyewear companies such as Warby Parker and Felix Gray promote the glasses’ potential to consumers. Warby Parker’s website states that “if screen time is affecting your sleep, blue-light-filtering lenses may help.” Felix Gray says on its webpage that wearing blue-light blocking glasses can reduce conditions such as eye fatigue, dry eyes and eyestrain. Neither company responded to email requests for comment.

Some makers of prescription glasses can charge extra fees — as much as $50 — for lenses that include blue-light blocking.

Blue light is a part of the visible light spectrum that has relatively short wavelengths, Downie said. We are exposed to blue light from digital devices and — at much higher levels — the sun.

Some eyewear companies claim that blue light emitted from our screens is a cause of eyestrain, but the American Academy of Ophthalmology has stated that blue light does not cause eyestrain, nor does it damage retinas or lead to diseases such as macular degeneration. The academy said studies on blue light showing damage to cells were conducted on cells in a dish and in animals. The experiments did not “mimic the natural conditions of blue light exposure to live human eyes and did not use blue light from computer screens,” the academy said in an article.

Eyestrain can happen when we look at screens for too long, Khurana said.

“Your eyelids normally blink 15 times a minute,” he said. “But when you’re concentrating on something, like looking at a screen or looking at a computer, your blink reflex goes down to maybe five to seven times a minute, and as a result, your eyes dry out.”

Eyestrain symptoms include tired, burning or sore eyes, and even blurred vision, Downie said.

Three of the 17 trials in the review evaluated blue-light reflecting lenses and eyestrain. The common outcome measure was a subjective visual fatigue score. All three trials, with a combined 166 participants, reported no significant difference in visual fatigue between those wearing blue-light filtering lenses compared with those wearing lenses that don’t filter blue light.

The review showed “expected findings,” said Kevin M. Miller, a professor of clinical ophthalmology at the University of California at Los Angeles who was not involved in the study.

“When the optical shop tries to talk you into the blue blocker, just say, ‘I don’t think so,’ ” he said. “That would be my response.”

Our brain has an internal clock known as the circadian rhythm that regulates, among other things, sleep. Light and darkness can affect this rhythm; short-wavelength light, such as blue light, is preferentially absorbed by photoreceptive cells in the retina that have the most effect on the biological clock. The light also suppresses the hormone melatonin which signals darkness.

Bright light, especially short-wavelength light, from devices, for instance, at night can confuse the biological clock and may make it hard to go to sleep or stay asleep.

The idea behind blue-blocking lenses is to stop the light from entering the eye and throwing the circadian rhythm off; however, this has not been established with any degree of certainty in clinical studies, Miller said.

The review examined six studies with a total of 148 participants on the effect of blue-light filtering glasses on sleep quality. The findings were inconsistent, Downie said, with three studies finding a significant improvement in sleep scores and three others reporting no significant difference between blue-light-filtering glasses and glasses with no blue-light filter.

Downie added that the patients in the studies had sleep or mood disorders. “They weren’t evaluating interventions in the general population,” she said. “So we can’t make any statement around the potential utility in relation to sleep in general, healthy adults.”

The review also found “little or no effect” with blue-light filtering lenses on visual performance and daytime alertness.

“Uncertainty in these effects was due to lack of available data and the small number of studies reporting these outcomes,” the authors wrote in the review.

Downie said the researchers attempted to look at the impact of blue-light filtering lenses on contrast sensitivity, color vision and whether there was any difference in what the authors called “discomfort glare” — a phenomenon where you get eye discomfort from bright light sources.

None of the studies reported on those outcomes, so the researchers could not draw any conclusions about possible effects of blue-light filtering lenses on the effect on the health of the back of the eye, Downie said.

There are things people can consider besides buying blue light glasses, experts say.

If the eyestrain persists, see an eye-care health professional who can perform a thorough examination of your eye health, Downie said. “Sometimes eyestrain can be actually caused by an underlying eye health or vision problem,” she said.

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