Sunglasses are more than a fashion accessory.

Sure, they do a great job of complementing your beach outfit, and we’ve all used them once or twice to hide tired eyes after a sleepless night.

But the main reason to wear them? They protect your eyes from harmful ultraviolet (UV) rays, which can reach your eyes even on a snowy or cloudy day, says Peter Harb, O.D., an optometrist at America’s Best Contacts & Eyeglasses in Tampa, Florida.

Since they’re so vital to your eye health, it’s important to know all the details about sunglasses before you buy. Here’s everything you need to know about sunglasses, including tips for picking the best pair for your lifestyle.

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What are sunglasses?

Sunglasses are dark or tinted lenses that are meant to protect your eyes from the sun’s powerful UV rays. Sunglasses also help people with light sensitivity, says Dr. Harb. There are three main types:

Prescription. If you already wear glasses, you can also get sunglasses with your prescription in the lenses.

Regular sunglasses. These can be worn comfortably by patients with little to no prescription, or worn with contact lenses, says Dr. Harb.

Clip-ons. These are sunglasses that clip onto your regular prescription glasses.

What are the different types of sunglass lenses?

Just like there’s no one right car for everyone, there are different types of sunglass lenses to fit people’s various needs:

Polarized. “These lenses help with glare and reflection, especially on the water or beach when sunlight bounces off smooth surfaces like pavement or water,” says Dr. Harb.

These sunglasses work by filtering out horizontal rays of light, says Dr. Harb. That’s the type of light that reflects off surfaces such as a snow-covered field and makes it hard to see. These lenses also help make colors appear brighter and details sharper, he says.

Polarized sunglasses are a good choice when you’re https://www.americasbest.com/blog/article/caring-your-eyes/ask-optometrist-are-polarized-sunglasses-better-my-eyesoutdoors hiking, on a boat, or swimming at the beach. Just keep in mind that polarization is unrelated to UV protection, so you’ll still need to make sure the lenses have UV coating.

Gradient. These are lenses that are shaded from top to bottom (usually dark on top and lighter on the bottom). They cut glare and allow you to see clearly out of the lower half of the lens.

Gradient lenses are good for driving, but not as helpful in snow or at the beach. In those cases, a double-gradient lens (dark on top and bottom and lighter in the middle) may be a better option.

Photochromic. “These lenses adapt to differences in surrounding light — they automatically turn dark outdoors in the sun, then back to clear and transparent indoors,” says Dr. Harb.

Since it’s a single pair of lenses, there’s no need to switch back and forth between multiple pairs, which makes them appealing for people who regularly wear glasses.

One company that makes these lenses, Transitions™, includes Transitions XTRActive. “This is the darkest formulation, and a good option for very light-sensitive patients,” says Dr. Harb. Transitions Drivewear works well behind the windshield, and Transitions Signature GEN8, the newest option, darkens in just seconds when outdoors.

Why are sunglasses so important?

Sunglasses protect your eyes from damaging UV rays in the same way sunscreen protects your skin. “Both types of rays, UVA and UVB, can damage three main parts of the eye: the cornea, the lens, and the retina,” says Dr. Harb.

UV exposure can also speed up the aging process, he adds, which raises your risk of developing the following conditions:

• Cataracts. This a cloudiness of the lens of the eye, which causes dim and fuzzy vision. While it’s caused by age, UVB light accelerates cataract formation. About 10% of cataracts are caused by UV exposure, according to the World Health Organization.
• Age-related macular degeneration. It’s thought that sunlight exposure raises the risk of this condition, which leads to a loss of central vision.
• Eye cancers. These include eyelid tumors, as well as cancer in the eye itself (known as uveal melanoma).

You can also get a sunburn of the surface of your eye, conditions known as photokeratitis or photoconjunctivitis. While these injuries will heal on their own, they are very painful.

Press play for more tips on the importance of wearing sunglasses:

Do I need to wear sunglasses in the winter? 

Yes! In fact, on snowy days, it’s even more important to sport your sunglasses. “In the winter, UV light can be intensified from sunlight reflecting off of the surrounding snow,” says Dr. Harb. 

It’s also important to wear sunglasses whenever you’re outdoors, even in the early morning or late afternoon. In fact, between 8 a.m. and 10 a.m. and between 2 p.m. and 4 p.m. are prime sunglasses times. That’s because the sun is lower on the horizon during these hours, so your eyes get a more direct hit.  

What should I look for in a good pair of sunglasses?

A reliable pair of sunglasses needs to offer strong UV protection, says Dr. Harb.

When you buy sunglasses, they should have a tag or sticker that either says they provide 100% UV protection from all UV light, or “UV absorption up to 400 nm” (that’s 400 nanometers, a measure of light wavelengths).

Here are a few other things to keep in mind:

• Darker doesn’t mean safer. A very dark lens doesn’t automatically translate into better UV protection. As long as the label states that the sunglasses provide 100% UV protection, you’re good.
• Bigger is better. Oversized or wraparound-style sunglasses are your best bet. Not only do they protect your eyes from UV rays (including rays that could enter through the sides of your sunglasses) — they also protect the delicate skin around your eyes.
• Color doesn’t matter. Sunglasses with colored lenses don’t block out more sun, but a brown or rose-colored lens will provide more contrast. You may find this useful if you play certain sports, such as golf or baseball.
• Opt for impact protection. All sunglasses need to meet U.S. Food and Drug Administration impact safety standards. But if you play sports such as basketball, baseball, or tennis, consider polycarbonate plastic sunglasses, which are shatter resistant.

What are my lens coating options?

There are three main lens coating options for sunglasses, says Dr. Harb. These can be applied to prescription or plano (non-prescription) sunglasses.

• Scratch-resistant. This coating makes your glasses less likely to scratch if you drop them or clean them with a rough cloth.
• Anti-reflective. Also known as anti-glare, this coating reduces the amount of light reflected off the surface of your lenses. Otherwise, the light bounces back into your eyes and could affect your vision.
• UV protection coating. If you fall in love with a pair of sunglasses that don’t offer 100% UV protection, you can opt for this coating on the lenses to safeguard your eyes.

How can I tell if the lenses of my sunglasses are made properly?

The American Academy of Ophthalmology recommends this quick lens quality check, which you can do at the store:

1. Look at something with a rectangular pattern, such as a tiled floor.
2. Now hold the glasses away from your face and cover one eye.
3. Move the glasses side to side, then up and down, while you look through the lenses. If the rectangular lines stay straight, then the lens are fine. If they wave or wiggle, try another pair.

How do I care for my sunglasses?

First, rinse with room temperature or lukewarm water, then wipe or clean them. Avoid hot water, which can damage lenses. Then use a lenses spray cleaner, says Dr. Harb. (If you’re in a pinch, you can also use a gentle dish soap.)

Then, wipe your lenses with a soft, clean, lint-free microfiber cloth. Don’t use the tail of your shirt — it might be tempting, but it can scratch your lenses.

Another no-no: leaving your sunglasses on your car dashboard. Excessive heat can warp the frames and lenses. Keep them in their protective case, and take them inside with you where it’s cooler, says Dr. Harb.

Will sunglasses protect me from all sun or UV exposure?

Unfortunately, no. Sunglasses won’t protect you from certain light sources, such as tanning beds or snowfields, which are permanent accumulations of ice and snow in mountainous regions.

Sunglasses don’t give you the ability to look at the sun either, so don’t try it. While sunglasses help protect you from the sun’s harmful rays, they aren’t strong enough to protect your eyes while staring directly at the sun.

And if your sunglasses aren’t big enough to protect the tender skin around your eyes, remember to apply sunscreen to those areas when you go outside.

How do I know if my sunglasses fit me correctly?

Proper-fitting sunglasses are key to sun safety. If yours don’t fit right, they could feel uncomfortable or slip down your nose, making you less likely to wear them.

The side pieces that extend from the hinge back over the ears are known as temples. You’ll want to make sure that they’re not too short, so that they don’t dig into the sides of your head, says Dr. Harb. You’ll also want to make sure the lenses themselves are large enough to cover your entire eye and eyebrow area. An optician at America’s Best can help you make sure you have the proper fit.

See our sources:
UV radiation overview: World Health Organization
Sunglasses and your eyes: Columbia University Irving Medical Center
Tips for picking the right sunglasses: American Academy of Ophthalmology