Sunglasses do not expire on a schedule, and a scratched lens still blocks UV. Replace a pair when the scratches are in your line of sight, when the frame no longer holds its shape, when the coating has visibly delaminated, or when it stopped fitting. Do not replace one because a number of years have passed.
There is a persistent piece of advice that sunglasses should be replaced every couple of years because "the UV protection wears off." It is worth being precise about this, because the honest answer is more useful than the rule of thumb.
Does UV protection degrade?
In most modern sunglasses, the UV filter is not a surface coating that can wipe off — it is incorporated into the lens material itself, or bonded within it. That kind of protection does not simply wear away with normal use, which is why a scratched lens generally still blocks UV.
The caveats are real though. Some cheaper lenses use an applied UV coating rather than an integrated filter, and a coating can be abraded. Severe heat — a summer dashboard, a hot car, repeated cycles of it — can craze or delaminate lens coatings and degrade the lens itself. And deep scratches physically remove material.
The practical upshot: you cannot tell by looking whether a lens still blocks UV, and you cannot tell by age either. If you genuinely need to know, most optical shops have a UV meter and will test a pair in seconds, usually for free. That is a far better answer than replacing a working pair on a calendar. The American Optometric Association is clear that 100% UVA and UVB blocking is the standard to hold a lens to — we cover why in UV protection explained.
The five signs a pair is actually finished
1. Scratches in your line of sight.Scratches on the periphery are cosmetic. Scratches through the center, where you actually look, scatter light and force your eyes to work around them — which is genuinely tiring on a long drive or a bright day. That is the point to replace, and it is about clarity rather than safety.
2. Coating delamination. Mirror, anti-reflective and hydrophobic coatings can lift, cloud or peel, usually after heat exposure or abrasive cleaning. Once a coating starts going, it does not stop and it cannot be repaired. A cloudy patch that will not clean off is a finished lens.
3. The frame will not hold adjustment.If a frame has been bent and straightened repeatedly, or a hinge has loosened past the point of tightening, the pair will keep slipping no matter what you do. That is a mechanical end of life — and worth distinguishing from the fixable slipping causes in how to stop sunglasses slipping.
4. The lens has separated from the frame. A lens that has come loose in its channel will keep moving, catch grit behind it, and eventually fall out. Some frames accept replacement lenses; most budget ones do not.
5. It never fitted properly.The most common real reason a pair should be replaced, and the one people are most reluctant to act on. A frame that pinches, slides or gives you a headache is not going to improve. Check the numbers against a pair that fits — our sizing guideexplains them — and treat the money already spent as sunk.
Repair before replacing
Three things are worth fixing rather than replacing. Loose hinges are usually a small screw that an optician will tighten for free. A bent frame can generally be straightened. And lens replacementis offered by most premium brands and some mid-price ones — which is one of the quiet arguments for buying up in the first place, since a budget pair is disposable and a premium pair is serviceable. We weigh that in are expensive sunglasses worth it.
Making a pair last longer
The two habits that matter most are unglamorous. Use the case— the single biggest determinant of how long a lens coating survives. And rinse before you wipe — dragging a cloth across a dusty lens is how most scratches happen, and the full method is in how to clean sunglasses.
Two things to stop doing: leaving sunglasses on a hot dashboard, which is what kills coatings and warps frames, and pushing them up onto your head for long periods, which stretches the temple arms and creates the slipping problem people later blame on the nose bridge.
The upgrade case, honestly
There is one good non-failure reason to replace a working pair: your use changed. A lifestyle frame that was fine when you drove to work is the wrong tool once you start running; a general polarized lens is the wrong tool once you take up sight-fishing. That is a genuine upgrade rather than a replacement, and the right destination is the roundup for your new use rather than a like-for-like repurchase. If your old pair still works, keep it as the car pair — which is exactly the two-pair strategy we recommend in best cheap polarized sunglasses.
Replace, repair, or keep?
Keep it
Scratches only at the periphery, frame straight, coating intact, fit still good. A scruffy pair that still works is still working.
Repair it
Loose hinge, bent frame, or a brand that offers lens replacement. All three are cheaper than a new pair and usually quick.
Replace it
Scratches through your line of sight, delaminated coating, a frame that will not hold adjustment, or a fit that was always wrong.
Test it if you are unsure about UV
Most optical shops have a UV meter and will check a pair in seconds. That beats replacing a working pair on a calendar.
