Eye specialist explains how to protect the eyes from blue light

Host Amber Smith: Upstate Medical University in Syracuse, New York invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. The largest source of blue light is from sunlight, but we're also exposed to blue light from flat screen televisions, computer monitors, smartphones, LED lights, fluorescent lights... ophthalmologists are concerned because of how much time many of us, including children, spend exposed to blue light because it can affect our vision. Here to explain is Dr. Mark Breazzano. He's a retinal surgeon and clinical assistant professor of ophthalmology and visual science at up. Welcome back to "The Informed Patient," Dr. Breazzano.

Mark Breazzano, MD: Thanks so much for having me, Amber. It's a pleasure to be back.

Host Amber Smith: So, can we start with, can you give us a definition of what blue light really is?

Mark Breazzano, MD: Absolutely. So blue light is also known as short wavelength light. It's in the visible light spectrum, and it's about 400 to 500 nanometers in wavelength. And basically the way that light works is, a longer wavelength means less energy that it holds, based on its frequency. This is one of the physics formulas. We could go much more into detail if we like, but essentially, blue light is relatively higher energy with its higher frequency and lower wavelength than other types of light. And with this short wavelength like has been of interest for a number of reasons.

Host Amber Smith: Why is blue light used in electronics?

Mark Breazzano, MD: Well, blue light is part of that visible light spectrum. So it's in sunlight. It's in electronics. And it's variably higher in certain electronics, including LEDs and other devices as you alluded to. And it's just part of the spectrum that is emitted from these devices. And so it's something that we're becoming more and more attuned to.

Host Amber Smith: Is the blue light from the sun, is that different than the blue light in our cell phone?

Mark Breazzano, MD: Well, it's different in that the amount of radiation that's given off by any particular source can vary, and it certainly is different from the sun compared to these other devices. And there's obviously other factors involved in terms of anything else inbetween that can pick up the radiation and absorb it before it reaches us. And in terms of radiation, visible light is one of those things. There's certainly other types of radiation as well on the electromagnetic spectrum that are far outside of what visible light is. But obviously that's a different discussion.

Host Amber Smith: Well, can you talk about the benefits of blue light because we need it, right?

Mark Breazzano, MD: Yeah. It's a very interesting topic because there has been a lot of hype around blue light recently. There have been some studies that show that blue light in particular has the ability to influence physiologic change within our own body compared to other types of lights. So specifically, some investigators have actually looked, monochromatic lights, so basically just a single blue light wavelength exposure over an extended period of time for several hours can actually induce these responses moreso than green or yellow wavelength that was tested in an artificial setting. And notably one of them is melatonin, which we know is an important regulating hormone for sleep. And it actually suppresses that sleep more than these other wavelengths do. But it's important to keep in mind that this is a very artificial setting. This is isolating one particular wavelength. And in the normal, natural, or even the way we go about our lives, we are constantly exposed to more than just blue light. So you'd have to be in a very specific situation to really replicate that scenario where you're going to have, "Oh, I'm getting blue light specifically, and no other type of light."

Host Amber Smith: So what are the risks of too much blue light? Why are ophthalmologists concerned about this?

Mark Breazzano, MD: I think there is a little bit of, concern might be a little strong in some ways, and especially now that what we're finding is that there's actually some mixed evidence in a lot of aspects of blue light. So there's three main concerns that people have brought up regarding blue light. One is direct phototoxic effects of blue light, given its higher energy and the way it's absorbed in the back of the retina, for developing disease and conditions like age-related macular degeneration, which is one of the leading causes of blindness in the developed world.

Number two is its effect on circadian rhythms and our ability to sleep. Number three is eye strain, problems with these electronics getting to be able to use them long term, and are they actually contributing to our ability to work and use these devices unhindered? And so there's basically three main issues that have been raised with concerns about blue light, and they each have a varying level of evidence to actually support these concerns.

Host Amber Smith: Are children at greater risk than adults?

Mark Breazzano, MD: So especially now with the toys and sort of entertainment that's easily at our disposal for allowing them to have additional screen time. Maybe in schools they're using screens more than we typically used. You know, there is certainly that concern, is there a new introduction of potential harm that wasn't there before? And this is one of those things where we obviously need to learn a little bit more about. But what's interesting is, in terms of eye strain, there have been several studies looking at prolonged exposure to participants in terms of primary outcomes related to that blue light. And there actually wasn't really a noticeable difference in those that used blue light blocking lenses, for example, compared to non-blocking lenses. And one of the main reasons or explanations for this is that it's a very multifactorial problem.

You know, getting strained from using the computer can often be explained by several different issues. Dry eye syndrome, for example, is very common among people. The tear film is incredibly important on the surface of the eye. And anytime we're using the screen, the blink rate can actually go down by half. And so when that happens, it actually can evaporate more and just become more dry from that standpoint. So really just lubricating the eyes with preservative-free artificial tears can be helpful, is often what I tell my patients. Or just taking a break from the computer, if you can do that. You know, a lot of us, especially with remote work and the pandemic and afterward and a lot of office work requires a lot of screen time. And so there are very conservative measures to help improve this. There are other aspects too. Just simple ergonomic things with sitting at the desk or the computer, making sure maintaining good posture, and these musculoskeletal components to eye strain or just general comfort can certainly influence us as well.

Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. I'm talking with ophthalmologist Mark Breazzano from Upstate about how to protect our eyes from blue light.

So let me ask you about digital eye strain. How would someone know that they have that? Are there symptoms to be aware of?

Mark Breazzano, MD: Yeah, and like we were discussing, some of these symptoms can be very hard to tease out from other aspects that affect the eye, including dry eyes. Sometimes there can be other aspects, ocular motor issues as well. So anyone with a history of a lazy eye as a child or strabismus (misalignment of the eye) that may have been corrected with surgery at some point. These things can be a little bit exacerbated with prolonged screen exposure. And I think one of the other important points to keep in mind is, screen exposure introduces a lot of light, and so there are things that can be done including blue light blocking lenses, which sound really fancy and can be great and certainly can reduce that blue light exposure.

But really, you look at the American Academy of Sleep Medicine and they recommend discontinuing any kind of screen exposure for at least 30 minutes before bedtime. That's the best thing you can do for your sleep hygiene. And then after that, if you think, "well, I really don't want to give that up." Okay, then maybe the blue light blocking lenses can be helpful to some degree. And there's mixed evidence on that. There's a few studies out there that show some benefit in sleep quality, but there are others that didn't really show much of a difference.

Host Amber Smith: When we talk about the screen time, how long is prolonged? Because you mentioned taking breaks, but how often do you need to take breaks?

Mark Breazzano, MD: Every person is a little bit different, but if you can do it at least maybe 20 minutes or so. That's been suggested and proposed by others. But I don't think there's really a hard and fast rule yet. And it's still early to know exactly is there really problems or is there really detriment to this?

Host Amber Smith: Are there long term impacts to the retina? I wonder, as a retinal surgeon, if you ever see patients whose retinas are damaged by excessive exposure to blue light.

Mark Breazzano, MD: Yeah, it's a great question, and it's one of the main three points I think brought up with this whole blue light discussion. We worry about, again, the age-related macular degeneration and the potential detrimental effects from that. The blue light, as we know from a lot of preclinical studies on several different animal models in the retina, that can create through the blue light, these reactive oxygen species, and A2E is actually a byproduct of this process that can be detrimental to the retina and it's been shown to in these experiments.

And so this has actually led for the basis of these concerns. But it really hasn't been proven yet, at least, with normal everyday life. And the thought is, is because in these experiments they use higher intensities of that wavelength, and it is just one wavelength, and so there's sub-threshold, meaning not quite the intensity level that we would normally expect. And they're actually a higher level. And then obviously throughout our everyday life there's potentially prolonged exposure compared to the experimental setting. So we have a chronic sub-threshold amounts of it compared to what was done in these experiments, and that may explain why we're not seeing it yet clinically.

And what's also interesting is cataract surgery is one of the most common surgeries performed in America. And one of the big things is, with cataract surgery, after the cataract is taken out, an intraocular lens is placed in its place. And these often are blue blocking. And numerous studies have actually looked at the effects of these blue blocking intraocular lenses. There has not been, it has not been shown to my knowledge yet that there has been an increase or decrease in age-related macular degeneration based on having a blue blocking inocular lens or not. So it is very interesting that it has not been shown yet, and despite the effort to introduce these blue blocking type of lenses.

Host Amber Smith: So it sounds like there's a lot still to learn about this. Does it seem like if there's damage to the eye from blue light, can that be reversed?

Mark Breazzano, MD: Unfortunately, when there's damage to the retina in many ways, phototoxic effects, not too uncommonly we will see injuries from laser pointers, which is called laser pointer maculopathy actually. A lot of the damage from this can be irreversible. Some might improve slightly over time, but there can be permanent damage. And the shorter the wavelength, the higher the energy, the more damage, typically, that we see. So, as a public service announcement, these blue lasers definitely more dangerous. Every laser pointer can be dangerous, but blue is definitely more, higher intensity, more severe than green, and then by red. So we're talking sequentially, increasing wavelengths, lower energy, less danger, relatively speaking, but we always need to be cautious around any of these devices.

Host Amber Smith: Does the damage from blue light always cause the person some sort of symptoms where they'll have dry eyes or blurry vision or some sort of symptom? Or could people have damage to their retinas without even knowing it's happening?

Mark Breazzano, MD: Well, if we go even shorter on the visible light spectrum, and we're going to the ultraviolet side of things, the cornea actually does a pretty good job of filtering out a decent part of the ultraviolet spectrum. And so glass blowers and those types of injuries with that kind of radiation at that extreme of the visible spectrum, or just beyond the spectrum, can actually lead to problems with the tear film and cornea that way. And depending on how severe the injury is, it can cause severe issues, but you hopefully, and usually it can be milder than that.

Host Amber Smith: Well, Dr. Breazzano, I appreciate you making time for this interview.

Mark Breazzano, MD: Thank you so much again, Amber. It's been a pleasure.

Host Amber Smith: My guest has been Dr. Mark Breazzano. He's a retinal surgeon and clinical assistant professor of ophthalmology and visual sciences at Upstate. "The Informed Patient" is a podcast covering health, science, and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe. Find our archive of previous episodes at Upstate.edu/Informed. This is your host, Amber Smith, thanking you for listening.