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Blue light is part of the spectrum of sunlight. Other sources include digital screens (TVs, computers, laptops, smart phones and tablets), electronic devices, and fluorescent and LED lighting. We all seem to be increasingly tethered to our devices and spend more and more time looking at screens. Savvy marketers have demonized blue light and frightened a lot of people into parting with their money. The global market size is projected to rise to $38 million by 2026, from $28 million in 2020.

Glasses and other devices that block blue light have become very popular. You can even buy skin care products that block blue light. And after cataract surgery, you can get an intraocular lens that filters blue light (the rationale for this is based on cell culture and animal studies; a large systematic review of human studies recently showed no demonstrable differences in outcomes).The websites that sell blue-light-blocking devices tell us that blue light is bad for your health because it:

  • disrupts the circadian rhythm;
  • causes digital eyestrain syndrome, with blurry vision, difficulty focusing, dry and irritated eyes, headaches, back and neck pain;
  • increases the risk of certain cancers;
  • increases the risk of obesity, heart disease, and diabetes;
  • increases the risk of depression; and
  • may cause permanent eye damage, age-related macular degeneration, and blindness.

Sounds pretty awful, doesn’t it? But how much of that is true? Are blue light blocking devices just a marketing gimmick, or should we all be using them to protect our health? How many of those claims are based on good evidence? What does the science say?

The evidence has been mixed, with both positive and negative studies, and studies of varying quality, so it can be hard to sort out the truth. There have been several systematic reviews. Experts who know far more than I do about eyes have reviewed the evidence, and I won’t try to reinvent the wheel by citing all the pertinent studies. The American Academy of Ophthalmology (AAO) provides expert advice on “Should You Be Worried About Blue Light?” and ““Are Computer Glasses Worth It?” They answer “NO” and “NO”. They say “there is no scientific evidence that blue light from digital devices causes damage to your eye”. We know that too much ultraviolet light increases the risk of cataracts, growths on the eye, and cancer; but we know less about blue light. Its effects are still being researched. Blue light exposure from screens is much less than the amount of exposure from the sun.  When people report discomfort after looking at screens, it is not because of blue light. People tend to blink less when looking at screens, and this causes eye strain and dry eyes.

The AAO spokesperson, Dr. Khurana, says that given there is no evidence blue light causes damage to the eye, taking preventive measures against it could be more harmful than the blue light itself. We know that “It’s premature to take preventative action against blue light—there could be unintended consequences”. Some studies suggest that not getting enough sunlight might interfere with the development of vision in children, and could increase the risk of myopia in teens and young adults. Instead of blocking blue light with glasses, the AOA recommends taking regular breaks using the “20-20-20” rule: every 20 minutes, look at an object 20 feet away for 20 seconds”. And if your eyes feel dry, use artificial tears.  Another article on the AAO website has more suggestions to limit eyestrain including “blink”; adjusting brightness, contrast, and glare; adjusting your position at the computer; and if you wear contact lenses, take an occasional break and wear your glasses.

What about sleep?

Blue light is known to affect the body’s circadian rhythm by suppressing melatonin production. Better sleep might be achieved by limiting screen time before bed and using the night mode available on many electronic devices.

Is anyone guarding the hen house?

False or unsubstantiated claims about blue light are rampant, and there has been little regulatory action. The glasses are not classified as medical devices and are not regulated by the FDA. In the UK, Boots Opticians were fined £40,000 for making unsubstantiated claims, and a spokesperson for the UK Association of Optometrists said, “…current evidence does not support making claims that they prevent eye disease”.

Conclusion: Mainly a gimmick, not supported by good science

The claims for blue light glasses and other products that reduce exposure to blue light are not based on credible evidence. They are good salesmanship, not good science. I can’t recommend them. But neither can I advise people not to try them. Any hazard is to your wallet, not to your health. They are probably safe, and who knows? They might invoke a placebo response that will make you think you feel better subjectively even when there are no objective improvements. Caveat emptor. I’m not buying.

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Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.