What Is UV400 Protection?

Updated 6/1/2024

There are a lot of good things you can say about the sun.

It gives off the light and heat that we all literally depend on for life.

…it looks cool.

Alright, well that’s still two very good things you can say about the sun.

Unfortunately, there are also some not-so-good things you can say about the sun. For example, the sun emits UV rays. If you’re not wearing UV400 protection sunglasses, that’s a big, big problem.

But before I explain what UV400 protection is, let’s start with the basics…

What Are UV Rays?

Before we talk about the importance of sunglasses with UV400 protection, let’s discuss the aforementioned UV rays and your ocular health.

By now, you’re probably wondering, “What are UV rays and why are they so obsessed with hurting my eyes?”

Good question.

As you probably know, UV stands for ultraviolet. Ultraviolet light is:

“...light [that] falls in the range of the EM spectrum between visible light and X-rays. It has frequencies of about 8 × 1014 to 3 × 1016 cycles per second, or hertz (Hz), and wavelengths of about 380 nanometers (1.5 × 10−5 inches) to about 10 nm (4 × 10−7 inches).”

If you’re like me, you totally already knew that and it makes complete sense. For those of you who aren’t super smart like me, it basically means that ultraviolet light is electromagnetic radiation that comes from the sun.

There are actually three versions. UVA and UVB are the kinds we’re dealing with here on earth. UVC rays are more powerful, but their higher energy levels get caught in our atmosphere, so they’re not much of a risk.

The Very Real Dangers of UV Rays

Now, at this point, you may have begun thinking, “Wow. UV rays sound awesome and are definitely not something I need to worry about.”

Oh, man.

You could not be more wrong.

While UVA is the weakest of the three, it’s still strong enough to cause indirect damage to the DNA in your skin cells and – arguably worse – wrinkles!

This was a yellow lab before UV rays did their thing 

About 95% of the UV rays that make it through the earth’s atmosphere are UVA.

The rest are UVB rays, which have a little more energy, enough to directly damage your skin cells’ DNA and cause sunburns. They are probably responsible for skin cancer, too.

Here’s how the American Optometric Association (AOA) describes the threat UV rays pose to your eyes:

“If your eyes are exposed to excessive amounts of UV radiation over a short period of time, you will likely experience photokeratitis. Like a "sunburn of the eye," photokeratitis can be painful. Its symptoms include red eyes, a foreign body sensation or gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. Fortunately, these symptoms are usually temporary and rarely cause permanent damage to the eyes.”


Sunburn of the eye”, it turns out, is as awful as it sounds.

And while it usually goes away within 72 hours, you also don’t need to be staring directly at the sun to get it. Simple overexposure – easy to do if you’re around snow, water, or any other reflective surface – can be enough to cause this terrible condition.

Anything else, AOA?

“The longer the eyes are exposed to solar radiation, the greater the risk of developing cataracts or macular degeneration later in life.”


Cataracts and macular degeneration? I was not expecting something to be worse than sunburn…of…the eye!

And here’s the worse part: you’re constantly being exposed to these UV rays if you and the sun are both out at the same time. Even retreating to the shade doesn’t keep your eyes safe.

Basically, the sun is trying to kill us, you guys.

But don’t worry.

There’s hope.

In retrospect, vampires may have been onto something.

How Sunglasses with UV400 Protection Can Help

Looking back, it shouldn’t come as much of a surprise that living on a planet so close to a giant dying star that has been exploding for billions of years might come with a couple of drawbacks.

Fortunately, we’re able to mitigate most of them.

Even better, the best way to keep your eyes safe from the sun will also make you look really cool.

But enough about our extremely affordable, durable, and fashionable sunglasses with UV400 protection.

Why is UV400 protection so important in the first place?

For that, we go to an article about sunglasses from TODAY, even though their logo is the sun, which we now know is actually humanity’s greatest enemy:

“When shopping for shades, the most important thing to look for is the level of UV protection offered by the lens. The safest bet is to buy sunglasses that provide 100% UV protection, or UV 400 protection. That means that the glasses protect your eyes from both UVA and UVB radiation.”

So, UV400 protection isn’t just protection against the sun’s terrifying UV rays. It’s the most protection against those rays.

Specifically, it refers to blocking out the aforementioned UVA and UVB rays, which can have wavelengths of up to 400 nanometers. Therefore, any protection that falls below 400 will leave you vulnerable.

And as we just touched on, your eyes aren’t safe just because you’re in the shade or it’s an overcast day. You might get flack for wearing your sunglasses at night, but at least keep them on until the sun goes to bed.

Do You Need to Wear Sunglasses with UV400 Protection?


If you want to experience the simple joys of having sunburnt eyes, then go right ahead and ditch the UV400 protection.

You definitely won’t regret it.

Everyone else should opt for sunglasses with UV400 protection, though. You’re not sacrificing anything by keeping your eyes safe. Many brands are actually very stylish and one, in particular, is even affordable (it’s us, you guys; we’re that brand).

It’s important to protect your children from the sun, too. According to the CDC, one of the best ways to do this is by having them wear sunglasses with UV400 protection.

What You Need to Know Before Buying UV400 Protection Sunglasses

Hopefully, you’re sold on the idea of wearing UV400 sunglasses from now on.

However, before you make your next purchase, confirm that the brand really does advertise “UV400 Protection.”

Whether on the website or the sticker, if you’re buying them in-person, you have to check for confirmation that you’re paying for UV400 protection. Many sunglasses will say “UV protection”, “UV blocking”, or some other vague description, but won’t actually protect against UV rays of up to 400 nanometers.

It’s not hard to find sunglasses with UV400 protection (ahem), so there’s absolutely no reason to settle for anything other than complete safety for your eyes.

In fact, settling for sunglasses that don’t have this kind of protection could actually do more harm than good. That’s because your pupils will actually open up more when you wear them just as they normally would when your surroundings dim.

Unfortunately, now your eyes are letting in more UV rays than they would if you hadn’t bothered to put those sunglasses on at all.

As a result, you might enjoy less glare and ambient light, but you’re actually increasing your chances of macular generation, cataracts, and even ocular melanoma.

Don’t Forget About Polarized Lenses, Too

Polarized sunglasses are fantastic for cutting out glare, which, in turn, will cut down on eye strain and make it easier to see.

While they don’t offer UV protection, you also don’t need to choose between the two. You can find high-quality, fashionable sunglasses that offer both (AHEM).

Protect Your Eyes in Style

Until scientists finally build some sort of super dome to protect our planet from that dumb dying star that pelts us with UV rays all day (literally), we’ve decided to take measures into our own hands.

At Runners Athletics, we believe that protecting your eyes against solar tyranny shouldn’t cost a fortune. We think you should even look good doing it, whether you’re enjoying drinks on a patio or trying to beat your personal best on the track.

Check out our selection of polarized sunglasses with UV400 protection and tell the sun, “You’re not the boss of me!”

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