Subtitles section Play video Print subtitles [♪♪] [Makda] We're in a galaxy of glasses. [Makda] Shopping for spectacles. There's choice galore. [Makda] Our secret shopper is a Marketplace producer and she really does wear glasses. The frames are all about fashion, but it's the lenses that are the real focus. [Makda] We're taking a hard look at a filter that's supposed to block the blue light from screens. [Makda] Blue light-filtering lenses are everywhere online, but we want to test how the country's big chains are pitching the latest trend in-store, so we're undercover inside Hakim Optical, LensCrafters, Vogue Optical, and Hudson's Bay Optical. We're visiting three stores for each of them. That means a dozen visits. [Makda] The sales pitch sounds and looks convincing. [Makda] And then the claims start to sound alarming. [Makda] At one chain, we even hear the "c" word. [Makda] Yikes. So what does it cost to save our eyes? [Makda] And it seems to be popular. [Makda] So should we all buy in? To find out, we're off to Philadelphia to visit one of North America's top eye specialists. Along the way, we meet people spooked by the light from their screens, too. I think using the computer or the cell phone for a long time can do harm. It can have retina detachment by using it too much time. I've heard that it's bad for you, so I got my glasses with the blue light lens protecting so that when I look at my computer screen or my cell phone, I'm at work, whatever, that it doesn't damage my eyes. If you look at screens too much, your brain and eyes can get damaged. Am I about to be duped? [Makda] So we're off to America's oldest eye hospital, established almost 200 years ago. Today it's 15 floors devoted to everything eyeballs. Look way up high. [Makda] That's where Montreal-born Dr Sunir Garg works. Awesome. Yeah, otherwise, your retina looks really great. [Makda] He's an eye doctor and an eye surgeon. Dr Garg is also a spokesperson for the American Academy Of Ophthalmology. We keep hearing the same thing about blue-light filter lenses. Is this a new thing? It's a new thing, and it's all over the internet. I can't even open up, you know, any website without, you know, "Hey, maybe you want to buy these blue light "blocking lenses." [Makda] Okay, then, let's hit play. [Makda] We heard that several times. Is blue light from your screens harmful? No. It's not. And I don't know where that's come from and why it's taken off so much, because it's not data driven. I can't fault them, because I'm sure they're getting a little info sheet that says you know what, here's three talking points about blue light blocking lenses. [Makda] He understands why we'd buy into this. I think people are thinking, Jeez, you're right, after I use my computer for a bunch of hours, my eyes don't feel very good. I can't see really well, they're kind of irritated, but what's bothering them isn't the blue light, it's the fact that when they're staring at the screen a lot, they're not blinking as often. That causes the eye to dry out and when your eyes become dry, they become irritated and scratchy and tired. [Makda] There is a simple fix for that. What you should do is just take a break and the American Academy Of Ophthalmology has this 20-20-20 rule. Every 20 minutes, take a 20 second break and look 20 feet off into the distance, and that will break that near staring that we tend to do when we're looking at the screen. [Makda] But back on hidden camera, we never hear that advice. Yeah. Tearing your eyes out would be really cool around Halloween, but it's not something, you know, that we see and I think people are exaggerating stuff. Well, Jeez, I have these light rays that are little daggers that are coming into my eyes and poking holes in my macula, which is sorta what she's making it sound like. She's saying "penetrating the eyes". That sounds scary. It does sound scary. And if I'm trying to sell you something that you don't need, maybe sounding scary helps to sell. [Makda] Now on to claims of serious damage to the back of the eyeball, Dr Garg's passion and specialty. This whole orange area is called the retina. The centre of the retina gets a special name. It's called the macula and the macula is the part of the eye that gives us our good reading and driving vision. [Makda] In our hidden camera, the staff in stores also bring up the retina and the macula. [Makda] Unfortunately, she's just wrong. And there's no evidence at all that blue light from the screen is gonna cause macular degeneration. [Makda] Blue light from our screens degrades our retina? I don't have patients coming in ever with any signs of damage to their retinas from looking at their screen all day. Retinal damage, macular degeneration, that sounds serious. And it IS serious, but the blue light from your screen is not the cause of that stuff. And people should do things to protect themselves against developing macular degeneration, but that's not buying these glasses. That's eating a proper diet, foods high in omega-3 fatty acids, eating stuff like broccoli, spinach, kale, three servings a week. We know that helps. [Makda] But we don't hear that in stores. We hear about studies. There are no studies that are showing that. Nothing in people. And so people will quote that. Yes, blue light can hurt retinal cells, but they're not telling you that's not been shown in a person or any group of people using screens, it's mostly in a petri dish or taking a poor mouse and holding its head in a position and shining a blue light intensely into their mouse eyeballs for hours on end. That can also potentially be harmful, but that's, again, not how it happens in people. [Makda] The marketing in stores also sends the same messages about the dangers of blue light from a screen. And so do the company websites. So everything that you have seen so far, what stands out? You know, I think people are exaggerating the problem and are misleading their customers. I think it's mostly benefiting the companies that are selling these things, truthfully. [Makda] We share our findings with the retailers. They declined to come on camera, but they say the science is still evolving and argue that blue light can be damaging. Some say they'll reinforce their staff training and add that blue light filter lenses won't harm consumers. And the makers of those lenses? They say people feel better using them and they reduce eyestrain. To get a second opinion about whether blue light from screens is harmful, we head to Oxford, England, to meet an optical radiation expert. Professor John O'Hagan knows all about blue light. Blue light in our normal environment is not dangerous at all. The main source of blue light for most people will be from the sky. [Makda] From the sky? Really? So how much blue light actually comes from our screens? We ask him to measure that for us. The light level coming from the phone is so low that we need to turn down the lights in the room and bring the blinds down, otherwise we're not going to measure very much. [Makda] Professor O'Hagan fires up the spectro-radiometer. [Professor O'Hagan] Levels are very low. Very low output. There is no evidence that the blue light from your mobile device is harmful. [Makda] Three years ago, Public Health England asked him to do similar testing.