When purchasing sunglasses, you may only focus on getting a style that suits your face and preferences. However, while you should feel good in your sunglasses, the real reason to wear them is to protect your eyes from harmful ultraviolet (UV) rays. Not all sunglasses are created equal — and just because they’re tinted doesn’t mean they offer true UV protection. Here’s how you can tell if your shades are doing their job.

What is Ultraviolet (UV) Light?

Ultraviolet light comes from the sun, but it’s invisible to the human eye. It’s part of the electromagnetic spectrum and helps the body produce vitamin D, which is important for calcium absorption. However, too much UV exposure can cause sunburn, tanning, skin aging, and skin cancer, so UV protection is essential:

Why UV Protection Matters

Prolonged exposure to UV light can lead to serious eye conditions, such as cataracts (clouding of the lens), macular degeneration (damage to the retina), photokeratitis (a sunburned eye), and even skin cancer around the eyes. It can also damage the lens, cornea, and retina, causing vision impairment or even blindness. Wearing sunglasses with 100% UV protection helps block both UVA and UVB rays, significantly reducing these risks.

Check the Label

The easiest way to tell if your sunglasses offer good UV protection is to look for a label or sticker that says 100% UV protection or UV400, which blocks all light rays with wavelengths up to 400 nanometers, including UVA and UVB. Be wary of vague labels like “blocks harmful rays” or “UV absorbing” without specific details.

Buy From a Reputable Source

Designer labels and brand names don’t automatically guarantee UV protection, but buying from a reputable store or trusted retailer does increase your chances. Avoid unbranded sunglasses or cheap knockoffs unless they’re certified.

If you want to buy them online, read reviews and only buy from reputable sellers. If the listing lacks details about UV protection, it’s better to skip it.

Use a UV Light Tester

Some optometrists or eyewear retailers have a UV light testing machine that can measure the amount of UV radiation the lenses block. If you’re unsure, bring your sunglasses in for a quick test. You can also use a UV flashlight and some UV-sensitive material, such as a dollar. Shine a flashlight through the lens and onto the material. If it doesn’t change or reveal any elements, the lens is blocking UV rays. 

Consider Polarization vs. UV Protection

A popular misconception involves the polarization vs. UV protection. Polarization is designed to reduce glare and improve visual clarity and comfort when viewing reflective surfaces like water or roads. However, polarization doesn’t always include UV protection. Always check for both features if you need them. 

Don’t Rely on Lens Darkness or Tint

Darker lenses don’t equal better UV protection. In fact, dark lenses without UV protection can be worse, because they cause your pupils to dilate, allowing more UV rays to enter your eyes. Always prioritize UV rating over darkness.

Similarly, lens color can affect contrast and visibility, but not UV protection. Always rely on the UV rating, not the shade.

Prescription Sunglasses Need UV Too

If you wear prescription sunglasses, confirm with your optometrist that your lenses include 100% UV protection. Most modern lenses do, but you may want to double-check — especially if you have older lenses.

Replace When Necessary 

Over time, UV coatings may not be as effective, especially if your sunglasses have been scratched or heavily used. If your shades are a few years old, consider getting them retested or replacing them.

Other Considerations 

When outside, you may want to wear a hat, preferably one with a wide brim, as this can help protect your face and eyes from the sun. Use sunscreen, especially on the sensitive skin around your eyes, and stay hydrated to keep your eyes healthy. Finally, stay in the shade when possible and take regular breaks from activities such as swimming and hiking. 

In addition, remember that UV rays remain present year-round — even on cloudy days. Snow, sand, and water all reflect UV light, increasing your exposure. Wear sunglasses daily —  no matter the season, especially if you’re at high altitudes or near reflective surfaces.

Protect Your Eyes with UV-Blocking Sunglasses

Your eyes are incredibly sensitive to sun damage, and UV protection plays an essential role; for this reason, it should not be optional. Make UV protection a non-negotiable feature when buying sunglasses, just like you would with sunscreen for your skin. Your future self and eyes will thank you.