The answer isn't as simple as it might seem. Here's what you need to know when thinking about whether to invest in blue light glasses.

By Lauren Mazzo
May 07, 2020
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When's the last time you checked out your phone's screen time log? Now, factor in the amount of time you spend staring at, say, a work computer, TV (hi, Netflix binge), or an e-reader in addition to your phone's little screen. Scary, huh?

As life has become increasingly dependent on screens, so has the market of products intended to mitigate the effects of all this screen time on your skin, bodies, and brains. One of the most notable? Blue light glasses—eyewear (with or without corrective lenses) that claims to protect your eyes from the harmful light rays coming out of all your favorite devices.

Sure, blue light glasses are a great excuse for anyone who's coveted the glasses look—but has 20/20 vision—to justify buying and wearing a pair. But do blue light glasses work, or is it all hype? And, for that matter, is blue light all that harmful to your eyes anyway? Here, experts answer all your Qs.

What is blue light?

"Blue light is much more complex than you might imagine," says Sheri Rowen, M.D., ophthalmologist and member of the Eyesafe Vision Health Advisory Board.

"Light is made up of electromagnetic particles called photons that travel in waves," says Dr. Rowen. "These wavelengths of visible and non-visible light are measured in nanometers (nm); the shorter the wavelength (and thus, the lower the nm measurement), the higher the energy."

Courtesy of Eyesafe

"The human eye perceives only the visible light portion of the electromagnetic spectrum, which ranges from 380-700 nm and is represented by the colors violet, indigo, blue, green, yellow, orange, and red," she says. "Blue light, also known as high-energy visible (HEV) light, has the shortest wavelength of visible light (between 380-500 nm) and therefore produces the highest amount of energy."

Yes, blue light comes from many of your digital devices, but it also comes from other man-made light sources (such as streetlights and interior lighting) and comes naturally from the sun. That's why blue light is actually considered necessary for vital functions, like regulating a healthy circadian rhythm (the body's natural wakefulness and sleep cycle), says Dr. Rowen. But that's also where issues can arise.

Is blue light harmful to your eyes?

Here's where it gets even more tricky. You've likely heard that blue light isn't great for your eye health. In fact, Ashley Katsikos, O.D., F.A.A.O., a dry eye specialist at the Golden Gate Eye Associates within the Pacific Vision Eye Institute says that, over time, cumulative exposure to HEV blue light may lead to specific long-term harm to your eyes, including potential damage to retina cells, age-related macular degeneration (damage to a specific part of your retina, which can lead to blindness), early-onset cataracts, pinguecula and pterygium (growths on your eye’s conjunctiva, the clear covering over the white part of the eye, which can cause dry eye, irritation, and, in the long-term, vision problems), dry eye, and digital eye strain.

However, other professionals—and the American Academy of Ophthalmology (AAO)—maintain that, while overexposure to blue light and UV light rays from the sun can raise the risk of eye disease, the small amount of blue light coming from computer screens hasn't been shown to cause any significant harm to your eyes.

"As far as we can tell right now, blue light is not damaging to the human eye, as you go about your daily life," says Sunir Garg, M.D., clinical spokesperson for the American Academy of Ophthalmology and professor of ophthalmology at Wills Eye Hospital. "Blue light is a natural form of light present in the sun—outside, you're getting way more blue light from the sun than you would from your phone screen, even sitting on there for a couple of hours a day. The human eye has done a pretty good job over thousands of years of evolution in filtering out much of the harmful light rays from the sun—and it's admitted from phones or tablets or screens but at much lower levels than is present in natural sunlight."

That said, your collective exposure to screens is truly excessive—many people stare at them for hour upon hour, day after day, for a majority of their lifetime. That's why Dr. Rowen argues that "though the amount of light emitted by digital screens is indeed much lower than that of sunlight, we now spend more time in front of screens without knowing the consequences of the cumulative effect of this low dose of radiation on eyes." Plus, due to technological advances, displays are getting brighter, and their integration in daily life is getting more complex, she says. Think about the AR/VR devices that are gaining popularity and how closely they hold a blue light-emitting device to your eyes.

It's worth noting that the risk of blue light might be a greater concern for children and young adults (under age 20) who are particularly susceptible because they have a very clear lens, and thus minimal blue filtration, says Dr. Rowen. Over time, as the lens in the human eye ages, "it becomes more yellow, thus filtering much of the blue light to which we are exposed," she says. "We don't know the long-term consequences of this high-intensity, blue-rich light on young children who will have possibly 80 years of digital device use."

What does the research say? A 2019 report by the French Agency for Food, Environment, and Occupational Health & Safety (ANSES) confirms that long-term exposure of the retina to blue light is a contributing factor to the occurrence of retinal degeneration, according to Dr. Rowen. A 2018 research overview published in the International Journal of Ophthalmology found that, while a certain amount of blue light can promote human eye development and regulate circadian rhythm, the harmful effects of blue light can include a degree of damage to the cornea, crystal lens, and retina in the human eye.

Although, Dr. Garg offers a counter-argument, saying that the existing studies mainly look at rats or lifted retinal cells hanging out in Petri dishes and involve exposure to "really intense blue light—sometimes a hundred or a thousand times stronger than would be present from phones—and for hours on end, which are not very good quality suggesting that blue light causes problems in people," he says. As a result, in the last year or so, researchers have started using consumer-like displays as the light source in their in-vitro experiments as well as low-luminance similar to those of digital screen in-vivo experiments on animals and observed cells damages upon cumulative exposure, says Dr. Rowen.

Head spinning? The takeaway: "There's so much we still need to understand about the mechanisms of light interaction with the retina’s cells and the eye’s capability to repair eventual damages," says Dr. Rowen. And, right now, there just isn't sufficient human research to show the effects of blue light in a way that's truly representative of how we're using it these days—you know, scrolling TikTok in bed and all.

Dry Eye, Digital Eye Strain, and Circadian Rhythm

When you add up all the time you spend gazing into screens, it's easy to see why blue light is thought of as potentially risky (after all, too much of anything is usually no good). That said, while we aren't entirely sure of the link between blue light and eye disease, all three experts agree that excessive screen time can certainly result in digital eye strain and/or dry eye, and can likely mess with your circadian rhythm.

Digital eye strain is a condition that describes general eye discomfort after screen usage and is commonly exhibited by dry eyes, headaches, and blurred vision. (Here's everything you need to know about digital eye strain.)

Dry eye can be a symptom of digital eye strain, but also refers to a condition in which a person doesn't have enough quality tears to lubricate and nourish the eye, according to the American Optometric Association. It can be caused by vision factors (like contact lenses and LASIK), medical conditions, medications, hormone changes, and age. And—yes—failure to blink regularly, such as when staring at a computer screen for long periods of time, can also contribute to dry eye symptoms.

"When you get up from staring at a computer for hours and your eyes hurt, that's a real thing," says Dr. Garg. But that experience isn't only from the blue light. "When you're staring at a screen for a long time, you don't blink as often, so your eyes get dry, and since you're not moving your eyes around—they're focused in one spot and not moving—any activity like that will cause your eyes to get fatigued and then feel bothersome," he says.

Circadian rhythm effects caused by blue light have also been challenged despite the well-accepted theory that it disrupts this important wake-rest pattern. No doubt, you've heard the "no screen time before bed" rule. Because your digital devices are emitting high-energy blue light (just like the sun), studies have suggested that too much blue light late at night can disrupt your natural circadian rhythm, which can cause sleepless nights and fatigue during the day, explains Dr. Rowen.

These studies show that blue light can suppress your body's production and natural release of melatonin (the sleep hormone), which can lead to disrupted sleep cycles—and all three experts agreed on this fact. However, a new 2020 study published in Current Biology suggests that blue light isn't to blame, exactly; researchers exposed mice to lights of equal brightness that were different hues and concluded that yellow light actually seems to disturb sleep more than blue light. There are a few caveats, of course: These are mice, not humans, the light levels were dim, regardless of color, which may not reflect the bright lights of electronics, and the researchers looked specifically at cones in their eyes (which detect color) instead of melanopsin, which senses light and is central to the issue of melatonin secretion, says Dr. Cathy Goldstein, a sleep specialist at Michigan Medicine in an interview with TIME.

While this new study challenges the blue light vs. melatonin theory, Dr. Rowen maintains that far more evidence lies in favor of the theory—and, as a result, you should limit blue light exposure before bed. "The results of several experimental studies conducted in humans, during which people were subjected to blue-rich light from artificial lighting or screens (computers, telephones, tablets, etc.), were consistent and indicated that nocturnal melatonin synthesis was delayed or inhibited even by very low exposure to blue-rich light," she says.

So, do blue light glasses work?

In terms of simply filtering out blue light, yes, they do work. "The lenses are coated with a material that assists with the filtering of the HEV blue light spectrum," says Dr. Rowen.

"Assuming it's a reputable company, they can hit those targets pretty effectively and cancel out a number of different wavelengths," says agrees Dr. Garg. For example, if you ever work with lasers and need to wear special protective safety glasses, they generally block the exact wavelength of the laser you're using, he says. So it's actually not like it's any crazy, new technology—which is also why blue light glasses don't (or shouldn't) cost a fortune.

"In terms of working, the primary issues people experience with prolonged screen time are digital eye strain, circadian rhythm sleep disruption, and other tell-tale signs such as dry eye, headaches, and exhaustion," says Dr. Rowen. And if you've heard from people who love their blue-light glasses, you probably won't be surprised to hear that "the majority of patients notice that they're working because their symptoms of eye strain and headaches go away even though they are not cutting down their screen time," says Dr. Katsikos.

If you want to try a pair, your eye care professional is your best resource for determining your specific requirements and to help determine what eyewear is best suited for your daily needs, as well as meeting or exceeding industry quality standards, says Dr. Rowen. "There are several good manufacturers of blue light filtering lens technology and because lenses are built to a prescription if needed, these lenses are made to the highest quality standards available. You might want to ask about glare-reducing anti-reflective coatings and photochromic lenses which provide good protection from UV and blue light while you are both indoors and outdoors."

Ok, but are they worth it?

While blue light glasses technically do work—as in, they do their job of blocking your eyes from blue light—whether they're worth purchasing is another question. Because, really, if the true effects of blue light on human eyes are still up in the air, so is the ability of blue light glasses to do anything to help.

And—surprise, surprise—research on the glasses themselves is somewhat inconclusive. A 2017 systematic review that looked at three studies on the effects of blue‐light-blocking lenses on visual performance, macular health, and the sleep‐wake cycle found no high-quality evidence to support using these types of lenses.

That said, aside from the cost, there's no huge risk in trying blue light glasses. "It’s generally not harmful to wear blue light blocking eyewear, so better to wear them than to not," argues Dr. Katsikos. Blue light glasses could run you anywhere from $17 online to $100 at a specialty eyewear store. You can also add the technology to your prescription lenses. (Whether or not your insurance covers them will depend on your vision plan, where you're buying them, and whether they're going on your Rx lenses or not.)

There is, however, one other interesting thing to keep in mind if you're thinking of going the Rx-lenses route: the potential reverse effect blue light glasses can have on your circadian rhythm—especially if you opt to put a blue-light-blocking filter on a pair of glasses you plan to wear for all your waking hours. "If you're blocking blue light at all hours of the day or night, that can also potentially have a negative impact on what we call entrainment onto the circadian rhythm," aka the synchronization of your circadian rhythm with external time cues, says Dr. Garg. If you're suddenly wearing blue-light-blocking glasses all day, your body might be thinking, "when is it going to be daytime?" he says. "Evolutionarily, we've become accustomed to blue light to help maintain our security rhythms, and if that goes away, that may have some negative consequences as well."

Luckily, the easiest thing you can do to combat digital eye strain, dry eye, and eye fatigue as a result of screen time is to practice simple eye exercises and take regular breaks while you're working in front of a computer or staring at another screen. Dr. Garg recommends the 20/20/20 rule: Every 20 minutes, take a 20-second break, and look 20 feet in the distance. "That'll force you to move your eyes around, and it'll help lubricate your eyes," he says.

And one super important thing to remember? Often, in the wellness world, the simplest tactics for taking care of your health go the furthest. "Of all the various things that you can do for your health and wellbeing, I don't think this should really be high on your worry list," says Dr. Garg. "Worry about maintaining a proper diet, don't smoke, and get moderate exercise. That stuff will definitely help keep your eyes healthy."

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