The short answer: Sunglasses carry no printed expiry date, but their UV protection can fade. Sunlight slowly breaks down the lens coating over roughly two years of heavy daily wear, faster on cheap lenses. Scratches also let glare and UV slip through. If the coating looks patchy, the lenses are deeply scratched, or the frame no longer sits straight, replace them.

Does UV protection wear off?

UV protection is built into or coated onto the lens. Constant sun, heat, and time can degrade that layer, especially on lower-cost lenses where the UV treatment sits on the surface rather than through the material. There is no exact clock. A quality pair worn part-time can hold protection for many years, while a cheap pair baked on a hot dashboard every day can weaken within a couple of seasons. If you are unsure, an optical shop can test a lens for UV in seconds.

Signs it is time to replace

• Deep or clustered scratches. They scatter light, strain your eyes, and thin the protective layer.
• Patchy or crazed coating. A cloudy, cracked film across the lens means the coating is failing.
• Faded or uneven tint. A tint gone blotchy points to age and heat damage.
• The frame will not sit straight. A bent frame throws off fit and lens angle, and stressed hinges follow.
• Loose, stretched arms. If adjustment no longer holds, the frame has given up.

How to make a pair last

Heat is the quiet killer. Keep sunglasses out of a hot car, where dashboard temperatures cook the coating and warp acetate. Store them in a hard case rather than a bag pocket, and clean them with lens spray and a microfiber cloth. Our guides on how to store sunglasses and cleaning without scratching cover the habits that add years. A hard case alone prevents most of the scratches that end a lens early.

Cheap lenses fail first

Price is not the whole story, but it matters here. A dark lens with weak or fading UV is worse than no sunglasses, because the tint opens your pupils and lets more UV reach the eye. That is the real risk of an old bargain pair. We explain the mechanism in do cheap sunglasses protect your eyes.

From our test bench. We run a UV meter behind lenses that have lived a hard life. Pairs stored in cases held near-full UV block after years. The failures share a history: left in cars, tossed loose in bags, wiped on a shirttail. One three-year-old pair from a dashboard read a clear drop in UV block, with a coating gone milky at the edges. Storage decided the outcome more than age.

FAQ

Do sunglasses lose their UV protection over time?

They can. Sun and heat slowly degrade the UV layer, faster on cheap lenses and on pairs left in hot cars. A well-made pair kept in a case can hold protection for years.

How often should I replace my sunglasses?

There is no fixed schedule. Replace them when you see deep scratches, patchy coating, faded tint, or a frame that will not sit straight. Heavy daily wear on budget lenses often means every couple of years.

Are scratched sunglasses bad for your eyes?

Deep scratches scatter light and make your eyes work harder, and they can thin the protective coating. If scratches sit in your line of sight, replace the lenses.

Part of The Eyewear Care Manual · Related: how to store sunglasses · Shop sunglasses · Last updated: August 4, 2026