Blue blocking glasses have become a popular way of protecting eyesight - but you probably don't need them

• People are increasingly concerned that bright light - especially "blue light" from computer screens - is causing harm, making it a potentially dangerous public health issue.
• Eyewear and screen protector companies have started to sell products they say can protect people from these harms.
• We do know that blue light at night can interfere with sleep, causing a host of negative effects. But the evidence that the amount of light screens expose us to during the day is harmful is not really there.
• Many experts think these products are unnecessary and could perhaps do more harm than good. Still, there's still a lot we don't know.

Many of us spend our days staring into bright screens.

Light can cause damage under certain conditions and some studies indicate that the most harmful part of the visible spectrum is blue light, which electronic devices emit to stay visible under bright conditions. Because of that, eyewear companies and screen protector manufacturers have started to market and sell devices designed to protect vision by blocking blue light.

But a closer look at the data reveals that these devices, as appealing as they sound, may not be the solution they're made out to be.

The pitch for protection

In recent years, interest in blue blocking lenses has surged. Glasses companies that have long sold eyewear targeted at computer users like Gunnar Optiks have put blue-blocking information on the front page of their websites, newer glasses companies like Felix Gray, among others, have sprung up to meet the seeming demand, The New York Times has written about the question of whether or not blue-blockers could help certain people, and Consumer Reports has put blue-blocking lenses to the test.

There are basically three elements to the pro-blocking blue light argument. First, proponents say doing so will help people sleep easier at night. Second, they say it will reduce digital eye strain. And third (and most significant, if the claim were true), they say blocking blue light may be necessary to prevent permanent damage to the eye that could result in disease. These diseases include macular degeneration, which causes people to lose some or at times eventually all of their central vision due to damage to the macula, in the center of the retina. (It's worth noting that these glasses aren't marketed as medical devices, so their claims are not regulated by the FDA.)

The idea that looking at screens causes permanent damage is a big claim, one that should be backed up by evidence in the form of scientific studies. But studies showing that screens cause this kind of harm do not exist.

It's not that light or blue light specifically is harmless, it certainly can be. But for now, there is no research showing that these devices expose us to enough light to cause any damage. Doctors do have explanations for why our eyes feel tired and stressed after looking at screens, but those explanations don't necessarily include light at all.

"People are very worried that we're looking at our screens more than we ever did," says Dr. Rahual Khurana, clinical spokesperson for the American Academy of Ophthalmologists. "Everyone is very concerned that it may be causing damage to the eye, and it's a valid concern, but there's no evidence it may be causing any irreversible damage."

Permanent damage in animals and cells - but not people

The research that companies selling blue-blocking products cite falls into three categories: animal studies, in vitro studies of retinal cells exposed to light, and studies of people exposed to outdoor light.

The first two sorts of studies there can give us reason to ask questions about how safe our devices are and to further research that topic, but they don't show harm. And studies of the sun are interesting, but being exposed to the sun outdoors and working in an office during the day are two drastically different environments.

Shining bright or blue lights into animal eyes can cause damage or changes that we'd associate with macular degeneration, but these experiments are pretty different than looking at your office computer or phone - and the eyes of mice, rats, and even monkeys are more vulnerable than those of people.

In the same way, we can shine lights on human and animal retina cells in a lab and cause similar damage. But again, this doesn't replicate the way we're exposed to light in the real world.

"I think it's largely hype, not science," says Dr. Richard Rosen, Director of Retina Services at New York Eye and Ear Infirmary of Mount Sinai and Ophthalmology Research Director at Icahn School of Medicine. "They want to sell it; they know people get uncomfortable staring at screens all day, so they say, it's because of this [blue light issue]."

"I don't think that anybody has shown screens are causing harm," says Rosen.

What the data tells us about macular degeneration

David Roger, co-founder and CEO of eyewear company Felix Gray, one of the companies that makes blue-blocking glasses, told Business Insider via email that there are "more and more studies on blue light's effects on macular degeneration."

Here's the issue: while there are studies like those mentioned above and studies about the effects of sunlight, there aren't studies that show computers or phones are exposing us to a dangerous amount of light.

Rates of macular degeneration are on the rise, according to the National Eye Institute (NEI), but the NEI attributes that to the fact that the population is getting older. The NEI still lists the primary factors that increase risk for macular degeneration as smoking, race, family history and genetics, and diet - not computer use.

But it's not just the aforementioned cell or animal data that indicates blue light might be risky, says Dr. Adam Berger, a retina surgeon at the Center for Retina and Macular Disease, who Roger put me in touch with when I explained that the doctors I'd contacted told me they didn't think blue light was increasing disease rates. Berger acknowledges that studies about computer use specifically don't exist, but his argument is a precautionary one - he thinks it's fair to extrapolate from other studies to say we should protect against blue light, even if it's hard to measure exactly how harmful computer use is compared to general day-to-day living in the pre-screen era.

Berger is not the only one. There are other doctors, some connected to the Vision Council, a trade group that represents the eyewear industry, that say they find that evidence convincing.

Those groups often point to studies that show that people who have spent a lot of time in the sun have an increased risk for macular degeneration. That's especially true for light-skinned people who typically have a higher risk in the first place.

White light, including that from the sun, includes blue light, and researchers have attributed the elevated risk of macular degeneration from sunlight to the blue elements of that spectrum.

"Everything we know is that cumulative exposure to light in general increases the risk of macular degeneration," says Berger. He says that it'll be difficult to measure exactly how much computer use affects the eye, but that he wears glasses by Blutech to block light in his day-to-day because he thinks "it makes sense to try to mitigate those effects."

That's the basic rationale the glasses companies offer too.

"Similar to reducing the amount of sun damage created by wearing sunglasses, wearing amber lenses also filters this harmful blue light from the eyes and prevents the long-term damage high frequency light can cause," Scott Sorensen, President of Gunnar Optiks, tells Business Insider via email.

But other doctors disagree with the idea of taking preemptive action against something when we don't know it's harmful - a new step may do more harm than good.

Khurana says it doesn't make sense to start recommending treatments, behavioral changes, or purchasing products when there still isn't proof that they're solving a real problem. "If we start jumping from the lab to making policy or to making recommendations, that's something we have to be careful of."

The studies that show that sunlight - and its blue spectrum specifically - raises risk of macular degeneration, are interesting, but comparing them to computer use may be misguided.

Many of these studies refer to people who work outdoors for multiple hours a day, people like Chesapeake Bay watermen who are exposed to bright sunlight and rarely wear sunglasses or eye protection.

The sun is far, far brighter than any light that we're exposed to indoors. A recent study on light exposure and its impact on sleep measured the light exposure for people camping outdoors in the winter and compared that exposure to the lights those people were exposed to indoors. Outdoor light - in winter, not as bright as summer - was 13 times higher than indoor lighting. The same thing is true for blue light. This study wasn't measuring light going into people's eyes directly, but it does show that people are generally exposed to far more light (blue light included) outdoors than indoors.

Extreme unprotected exposure to the sun isn't good for our retinas, but indoor conditions aren't replicated by those studies.

The primary culprit: Digital eye strain

"Digital eye strain" is really the primary culprit behind the dry, irritated, fuzzy feeling that many of us have in our eyes at the end of the day.

But both Khurana and Rosen say that the two main causes of eye strain are not blinking and having an improperly set up workspace. You want your screen brightness to be on a similar level to the surrounding room - your eyes may strain if that's not the case. Glare can cause eye strain, but the best ways to fix it are to use a matte screen and to make sure your lighting is well set up.

And most importantly for eye strain, we blink less when we focus intently on something like a computer screen (or a book). Instead of blinking around 15 times a minute, we'll do so 12 or 10 times. Doing that is enough to make our eyes feel dry and unfocused, says Khurana.

"Over the course of the day if [cornea cells] dry out beyond a certain point, they can't recover," says Rosen. "Not until they're replaced overnight will you feel comfortable."

Eye drops can help, says Khurana. Following the 20-20-20 rule - looking away from your screen at something at least 20 feet away for 20 seconds every 20 minutes - can also help. And the American Academy of Ophthalmology has some more tips. Eye strain is uncomfortable and irritating, but fortunately it's not associated with permanent damage.

Screens, melatonin, and a good night's sleep

As for blocking blue light while looking at screens at night to not impede melatonin production, that may make sense (though an app or filter may work for that purpose too).

Bright light (blue especially) is a cue that stimulates us and tells us that the sun is up - which is why we think it may confuse our brains at night. Studies show that looking at screens in the evening seems to stop or delay our brains from producing melatonin, a hormone that helps regulate circadian rhythm and helps us fall asleep. We think that's part of the reason why people who use screens at night don't sleep as well and may suffer some of the negative effects that come along with poor or insufficient sleep. By blocking blue light at night, glasses companies, screen filter manufacturers, and app designers all argue we'll interfere less with melatonin production.

Berger says he thinks this issue could perhaps be one of the most important reasons to wear blue-blocking glasses, since people feel the effects of a bad night's sleep immediately, long before potential damage may or may not manifest itself.

But on that front too, the best solution is probably to learn to be disciplined about device usage. It's only when you're getting ready for bed (or about an hour before) that you want your brain to know that it's time to start that melatonin production cycle.

Blocking or shifting away from blue light at night may help with the melatonin issue, but having access to a digital device interferes with sleep even when people don't look at it. Yes, some stimulation might come from light, but just the possibility of tapping into the vast and entertaining world that our phones give us access to is enough to make it hard to sleep, whether we have access to light or not.

The 'just in case' argument

Part of the argument about potential eye damage hinges on the idea that it may make sense to block blue light from reaching the retina, "just in case" it might cause eventual damage to the eye.

But this, in fact, could potentially do more harm than good.

People need light, blue light included.

During the day, blue light stimulates us, helps wake us up, and kick-starts our metabolism. Blue light in daytime is "very important for stimulation," says Rosen.

Blue light also also helps us regulate our circadian rhythms and our hormones. Blocking that light at night seems fine, but from the morning until evening, it's good that we're exposed to light that prevents us from producing melatonin and getting ready for sleep - this is natural.

Data shows that unprotected exposure to the sun can cause problems, which is why doctors advocate wearing sunglasses. But if we don't have evidence that indoor light exposure from screens is hurting our eyes, taking steps to block out that light may not be good for us.

In general, more light isn't necessarily a bad thing! It's true, for example, that myopia - nearsightedness - is on the rise for certain groups of kids, many of whom spend a lot of time indoors (presumably, in front of computers). This is separate from concerns about eventual eye damage, but it is something that comes up in discussions of "screen anxiety." But the thing that seems to prevent vision loss for these kids isn't blocking away light, it's spending time outdoors, where they look at things of different distances, all while being exposed to far more light than they would be indoors.

The need to see proof

It's possible that future research will reveal something new, that perhaps there is some elevation of risk from light exposure that hasn't been seen so far.

For now though, the research doesn't show that blue light is causing harm, even if some glasses manufacturers do think that's the case.

"I believe there will always be naysayers on any new topic," says Sorensen. "Unfortunately, we have found that the eye care professionals are the least informed on this topic."

But many of the sources who make the strongest claims about blue light - the ones who say there's definitely damage being done - are ones that have a stake in the matter. Much of the research that's promoted as definitively showing the dangers of blue light comes from these companies. For example, the study referenced on this Harvard Health page is sponsored by a company that makes a screen protector designed to block blue light. Also, even though that study was promoted in media as indicating a future "global epidemic of blindness" for people, it still relies on rat and on cell culture studies, not on signs of damage in humans.

This doesn't mean this research should be dismissed but when the main studies indicating a problem come from people who are selling a solution to that problem, that research should be scrutinized extra carefully. And so far, the evidence that harm is happening isn't there.

The technology that we use is going to continue to change over time, and each new development brings new risks, challenges, and benefits. As screens have improved and matte screens have become more common, screen glare has become less of an eye-strain issue, for example. We still don't have a very good idea of how long-term virtual reality usage will affect our eyes (or our brains), though that's something we're learning about now. We're still learning about the effects that new technology has on our eyes.

But in general, we try to avoid taking unnecessary steps. If you like glasses as a stylistic choice, that's one thing. But you probably don't want to block all blue light during the day.

If you compare sunlight to indoor light, it's likely that most of us aren't even getting enough light during the day. The fact that we continue to live in this indoor light at night instead of being surrounded by real darkness could also be an issue. Really, for circadian or sleep schedule purposes, humans need both light and dark - and we're probably not getting enough of either.

In general, says Khurana, if you feel like you are having vision trouble you should go see an eye doctor.

"I wouldn't recommend patients use any special type of computer glasses except glasses to correct their refractive errors," says Khurana. If you aren't seeing right, "have glasses corrected," he adds.