Do your sunglasses provide enough UV protection?
Protection from the sun’s harmful ultraviolet (UV) rays is the most important quality of effective sunglasses, but how can you tell if sunglasses have UV protection? The best way to find out is to look for a label, specifically one that says UV 400 or 100% protection against UVA and UVB rays.
Want to be sure your sunglasses protect you from the sun's harmful rays? You can take your sunglasses to an eye care professional or perform a simple test with your shades to see how well they block UV rays.
Why is UV protection so important?
Exposure to UV radiation from the sun can harm your eyes and endanger your vision.
In particular, cataracts, which develop when the naturally clear crystalline lens inside the eye becomes cloudy or opaque, have been linked to sun exposure. Studies have shown that the more time people spend in the sun, the greater their risk of getting cataracts as they age.
Excessive UV exposure has also been linked to corneal sunburn, retinal tissue damage, macular degeneration and abnormal growths on the surface of the eyes.
Sunglasses that block 100% of UV radiation can help protect your eyes against these risks.
When should you wear sunglasses? Put on your sunglasses whenever you’re outdoors during daylight hours, even when it’s cloudy. Although cloud cover blocks some visible light, it doesn’t prevent damaging UV rays from reaching the Earth’s surface.
How much UV protection should sunglasses have?
Ideally, you want your sunglasses to have UV 400 protection. UV 400 blocks nearly 100% of the sun’s harmful ultraviolet light rays. This helps ensure light rays with wavelengths up to 400 nanometers, such as UVA and UVB rays, are blocked.
To be considered UV-protective sunglasses, your shades must filter out 75% to 90% visible light and offer 100% protection against UVA and UVB radiation.
Most sunglasses are labeled to show how much UV protection they provide. Look for labels that specify 100% UVA-UVB protection or UV 400.
Additionally, sunglasses with larger lenses or wraparound-style frames will provide better protection against UV rays reaching your eyes from all angles.
Polarized lenses, which have special filters that reduce glare from reflected light, aren’t necessarily UV-protective lenses.
Bottom line: It’s critical to check labels when you’re shopping for a new pair of sunglasses to be sure you are getting 100% UV protection.
Do dark sunglasses have better UV protection?
There is no relationship between the color or darkness of your sunglass lenses and the amount of UV protection they provide. The lens tint color and shade intensity only tell you how much and what kind of visible light is blocked.
For example, lighter amber tints enhance contrast. Darker amber hues help prevent glare, and gray lenses lessen brightness.
Wearing darker lenses might actually put your eyes at greater risk. Your pupils will dilate when you wear darker sunglass lenses, allowing more light into the back of your eyes than would enter if you were wearing no sunglasses at all.
If you prefer to wear sunglasses with darker or more heavily tinted lenses, make sure they also provide 100% UVA-UVB or UV 400 protection.
How to test sunglasses for UV protection
UV-protective sunglasses block the sun's harmful rays because the lens material, or coating that’s been applied to the lenses, absorbs UV radiation.
An eye care professional can test your sunglasses in a few seconds with an instrument called a photometer and tell you exactly how effective your shades are at protecting your eyes.
You can also try a simple test at home if you have access to a UV flashlight:
- What to do – Shine the UV flashlight onto a piece of paper money. Newer U.S. paper currency contains UV-fluorescent fibers that will glow when exposed to UV radiation.
- What to look for – If the beam from your UV light source causes the fibers to glow even after it has passed through the lens of your sunglasses, you’ll know that your sunglasses don’t provide adequate UV radiation protection.
Note that sunglasses with scratched lenses might not provide as much sun protection as those without scratches, especially if their UV protection comes in a coating rather than being embedded in the lens.
It’s especially important to have older sunglasses checked to make sure they continue to keep your eyes healthy when you enjoy time in the sun. To test the UV protection of your sunglasses, visit an eye care professional near you.
