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The Case for and Against Blue Light Blocking Glasses (2020)

Posted by Zenobia Chan on 18 February 2020

It’s been two years since the Blue Light Hype hit the eyewear market. So, let’s reflect on how far the tech has progressed and what the market is doing. In this article, we weigh up the good and the bad, look at what blue light really is and if it’s a good market for eyewear retail. We look at the most recent studies and weigh up all the facts to see if your blue light blocking glasses are doing what they claim in the sales pitch.

Two years on and the general public is still increasingly concerned that exposure to bright light, particularly blue light, is causing harm to both their eyesight and general health. There are numerous articles online (and published) citing both successful and not so successful tales of blue blockers. But, who are we to believe. We can see straight through articles with affiliate posts with obvious links to Amazon accounts, but there are also some truly compelling articles to draw from here. 

So let’s look at the facts. 

We know that blue light can interfere with your sleeping patterns, considering the Harvard study Blue light has a dark side is anything to go by. Not taking anything away from Harvard, but there have been no further studies of consequence since. And the major selling point for blue blockers is that they block blue light from electronic devices, also during the day.

We associate blue light digital equipment, but according to Rahul Khurana, an ophthalmologist and clinical spokesperson for the American Academy of Ophthalmology, the negative effects of blue light and eye strain on your eyes are two separate issues.

“We keep on thinking about blue lights from our computers and smartphones, but the reality is we get more exposure from blue light from the sunlight.”

The most common symptoms associated with Computer Vision Syndrome (CVS) or Digital Eye Strain are

  • Eyestrain
  • Headaches
  • Blurred vision
  • Dry eyes
  • Neck and shoulder pain

Imagine spending time under a bright sun without sunglasses for the duration of a work-day. It’s arguably not only blue light that’s adversely affecting our eyes but the fact that we’re staring at computer screens for the better part of the day, without breaks.

So it needs to be said early on in this article that the best advice you can provide clients/patients/friends (before suggesting blue light blocking glasses) is to give the eyes periodic rest breaks during the day. The AOA suggests you rest your eyes for 15 minutes after two hours of continuous computer use. As well as, anti-glare screens, good lighting, seating position and more. 

That being said, let’s explore blue light further.

What is Blue light? Is it harmful? Where does it come from?



Blue light is part of the visible light spectrum and reaches deeper into the eye than any other light in the spectrum. As part of the visible light spectrum, blue light is the high-energy light just beyond the potentially harmful ultraviolet light.

The average proportion of blue light that's found in sunlight during the day is between 25% to 30%. Its cumulative effect can cause damage to the retina. Tests have established that in certain wavelengths, blue light is a known culprit in the development of age-related macular degeneration or AMD. 

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However, the amount of blue light you’re exposed to depends on where you’re located in the world, time of day and season. Even on cloudy days, up to 80% of the sun's UV rays make it through the clouds. Simple, just wear good quality sunglasses right? Not quite, what about using electronic devices during the day? Electronic devices automatically adapt to bright light by becoming even brighter, which is what most companies are using as a selling point for blue-blockers. 

Many of us spend our days staring at bright screens, including the young generation, in spite of our better judgement. However, the study of damage from blue light coming from electronic devices used during the day has yet to yield conclusive results. 

Fair enough, light can cause damage under certain conditions, and certain studies indicate that the most harmful part of the visible spectrum is blue light, which electronic devices emit to stay visible under bright conditions. But to what extent?

An array of Eyewear and screen-protector companies are now selling products they claim can protect people from such harm. But some experts believe wearing blue light blocking glasses might be doing more damage than good. 


The Sales Pitch

The interest in blue-blocking glasses has soared, well-established eyewear companies like Gunnar are even displaying products on their Home Page. There are numerous articles online, like this one in The Strategist, questioning whether or not these products can help certain people. Consumer Reports has put three different blue-blocking lenses to the test.


Blue Light Blocking Lens Test:



What are Blue-light Blocking Lenses Good for?

Proponents say wearing blue blockers will:

  1. Help you Sleep better
  2. Prevent permanent damage to the eye including Macular Degeneration
  3. Reduce Digital Eye Strain

However, the notion that looking at digital screens causes permanent damage is a bold claim, one that really needs to be backed up by evidence from scientific studies.

At the moment (even two years on) there are no conclusive studies showing that blue light from screens cause permanent damage, at least not to our knowledge at the time of writing this article (if you can provide evidence otherwise, please feel free to add your insight into the comments section below.)


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We’re not saying that light, in this case, blue light can’t damage your eyes, it can definitely have negative effects especially in low light circumstances. Otherwise there wouldn’t be a need for good quality sunglasses.

But there isn’t any research backing up claims that these electronic devices expose us to enough light to cause damage. Eye doctors have many explanations for why our eyes feel tired and stressed after prolonged periods of staring at screens, but these mostly don’t include light.

Adam Gordon, O.D., clinical associate professor at the University of Alabama at Birmingham School of Optometry is quoted saying “overuse and exposure to blue light may lead to eyestrain and focusing problems, but does not appear to cause long-term harm, eye disease or damage to the retina” in the article Debunking digital eyestrain and blue light myths.


Digital Eye Strain

Blue light blocking glasses

Digital eye strain is caused by the overuse of digital media such as smartphones, tablets, computers and good old television. Digital Eye Strain or Computer Vision Syndrome (CVS) is the result of eyes having to refocus themselves to process graphics and text continuously.

Digital screens are made up of millions of tiny pixels brought together to make a recognisable shape and movement, often becoming distorted which causes strain for eyes.

Staring at a screen decreases the average blinking rate, which can cause uncomfortable dry eyes. On average, we blink around 18 times per minute, and the purpose of this is to moisturise our eyes. However, when using a computer screen or the like, our blinking rate drops to approximately nine times a minute, resulting in our eyes not receiving as much moisture as they need.

The result?

Dry, irritated, fuzzy eyes at the end of the day. Screen glare can cause a lot of eye strain, but this can be easily fixed by using a matte screen or using a free program like f.lux which makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day.

Eye drops can help, and remembering to take regular breaks, try using a free online site Tomato Timer to keep you on track.

Eyestrain is uncomfortable and irritating, but luckily not associated with permanent damage and more importantly not a direct result of Blue Light.


Current Research Parameters

Companies selling blue-blocking products are using three categories to test for the effects of blue light. 

  1. In Vitro Studies of retinal cells exposed to said light
  2. People Exposed to outdoor light
  3. Animal Studies

Although all these methods have merit, the tests are by no means conclusive. We can shine a light on human and animal retinal cells in a laboratory and cause-related damage. But, this doesn’t really replicate the exact manner in which we’re exposed to light in the real world.

Studies of the sun and its effects are interesting, but you can’t compare exposure to the sun to exposure to electronic devices in an office all day long. These two environments are vastly different.

Using poor defenseless animals and shining bright lights into their eyes is just cruel by nature, and will probably cause damage that we associate with macular degeneration. But again, these experiments are different from staring into a phone or office computer. And besides, the eyes of traditional lab animals like that of rats, monkeys or mice are much more vulnerable than that of people.

Melatonin, Screens and A Good Night's’ Rest

Blue light blocking glasses-1

Blue blockers claim to improve your sleep, and all the research suggests that this is in fact, true.

According to the article - Blue Light-Blocking Glasses May Help With Sleep, Cognition - “Lenses that filter blue light almost doubled nighttime melatonin levels, reduced awakenings, and enhanced at least one measure of cognition in a randomized controlled trial that assessed these outcomes in wearers of BluTech Lenses.”

The study examined the effects of modifying short-wavelength blue light exposure on evening melatonin levels, sleep onset, mood, and cognition in a randomized controlled crossover trial. Twenty-four undergraduate students wore BluTech Lenses for 1 week and clear lenses with anti-reflective coating only (control) the next. The lenses were fitted into spectacle frames with blackout side shields and worn after 6:00 pm for 5 days (Monday - Friday).

The students wore actigraphy watches, which noninvasively recorded sleep patterns each night. On the fifth evening, saliva samples were collected to quantify melatonin levels; self-reported mood and neurobehavioral performance were assessed with the National Institutes of Health Toolbox Emotion and Cognition batteries, respectively.

For wearers of BluTech Lenses, mean melatonin level was 9.6 pg/mL compared with 4.9 pg/mL for the control group (P = .036) During the week they wore the BluTech lenses, participants had an increase in melatonin levels, less awakening during sleep, and evidence of improved cognition compared with the week they wore clear lenses, Van reported.

Bright light, especially blue light, is the cue that stimulates us to make us aware that the sun is up, which is partly why researchers believe this may be confusing our brains at night. Studies, like the one above, show that prolonged exposure to screens in the evening delays or even stops our brains from producing melatonin, a hormone that helps regulate circadian rhythm which helps us fall asleep.

Which leads us to believe that people who use screens at night don’t sleep as well as those who don’t indulge in a bit of screen time before bed. Eyewear companies, screen-filter manufacturers, and app designers will all argue that wearing blue light blocking glasses at night will reduce interference with melatonin production.

For that reason, one of the most important reasons to wear blue blockers is to improve sleep patterns, even long before the damage starts to manifest itself.

Blue light is getting a bad wrap, but we are very much dependent on light as well. Daytime blue light is essential for stimulation. Blue light also helps us regulate our circadian rhythms and our hormones. Blocking that specific light at night seems fine, but from the morning until evening? Perhaps not. It’s good that we're exposed to light that prevents us from producing melatonin and getting ready for sleep, it’s natural.


How Do You Test Blue Light Blocking Lenses?

There is an abundance of blue light blocking tests online that claim to test these lenses, but in truth, only a laboratory can properly test the effectiveness of said lenses.

In the article 3 Blue Blockers Put to the Test they tested three pairs of glasses in a laboratory for their ability to block blue light, measuring light intensity at all wavelengths to find out how much each lens absorbed.

Of the three, only one — the Uvex Skyper safety eyewear (orange tinted), $8—cut out almost all blue light.

The Gunnar Intercept gaming glasses (medium yellow), $53, cut blue light by about half, and the Spektrum Pro Blue Light Blocking Glasses (light yellow), $40, cut it by only about a third.

Note that none of the blue blockers claims to be medical devices (intended for use in the diagnosis or treatment of a disease or condition), and isn't regulated by the Food and Drug Administration.

The equipment used in each lab tends to vary somewhat, but at PEL we make use of only the best equipment available, in this case, a HITACHI U-4100 Spectrophotometer measurement system for optical parts. With skilled staff and calibrated equipment PEL can test precisely how effective Blue Blocking glasses are before you put them on the market.




It’s likely that research in the future will reveal new findings, which could indicate an elevated risk to our eyes from exposure to blue light. Screens have improved, and matte screens have become more common and screen glare has become less of an eye-strain issue. We still don't have a clear idea of the long-term effects virtual reality usage will have on our eyes or our evolution as a species really, though it's something we're exploring from all angles. In short, we're still learning about the effects that new technology has on our eyes.

We’re not saying the current research should be dismissed, not at all. But when the main studies indicating a problem come solely from the companies selling the solution, that research should be poured over carefully. But as long as you’re planning on putting blue-blocking lenses on the market you better make sure they do what they are supposed to.

If you’re unsure about how you should testing blue-blocking lenses, or what you can be doing do to ensure the quality of your eyewear get in touch with an expert at PEL.

Any cautionary tales about blue blockers you can share with our readers? Please leave a message in the comments section below.


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Topics: Eyewear Manufacturing

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Zenobia Chan

Zenobia Chan is PEL's General Manager, and has been working in the eyewear industry for over 17 years. She has been involved in the entire supply chain from research and development, to order fulfillment, quality management, auditing and product compliance. She established PEL from scratch and is an annual seminar speaker at the MIDO and Hong Kong Optical Fair.

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