Care
How long do sunglasses last, and does UV protection wear off?
Sunglasses do not expire, and UV protection built into the lens material does not wear off. What can wear off is a UV-blocking coating applied to the surface, and what actually ends a pair's life is more ordinary: scratches in the line of sight, a mirror or anti-reflective coating that has flaked, hinges that have loosened, or frame plastic that has gone brittle. A pair looked after with the right cleaning and a case lasts years. A pair wiped dry on a shirt hem and left on a dashboard lasts a season. The calendar has nothing to do with it.
Does UV protection wear off?
It depends on where the UV protection is.
In the lens material. Polycarbonate, tri acetate cellulose and most modern lens plastics absorb UV by their chemistry. That absorption is a property of the material, it is the same at the surface and in the middle of the lens, and it cannot be scratched or washed away. A lens like this blocks UV until it is thrown away.
As a surface coating. Some lenses, particularly older or cheaper glass and acrylic ones, get their UV block from a thin coating applied to the outside. A coating can be scratched through, and it can degrade with years of sun and cleaning. This is the origin of the idea that sunglasses "lose" their UV protection.
You usually cannot tell which you have from the label. An optician's UV meter can check any pair in seconds, and that is the honest test if a pair is old and you rely on it.
Our lenses are tri acetate cellulose, which absorbs UV as a material, with an additional UV coating stated by the frame maker. The material's absorption is what lasts.
What actually ages
| Part | What happens | How to tell |
|---|---|---|
| Hard coat | Scratches accumulate; the lens hazes | Look at a light through it; a fog of fine lines |
| Mirror coating | Wears at the edges, flakes with harsh chemicals | Patches where the mirror is gone |
| Anti-reflective back | Peels or crazes, often from heat | A rainbow film lifting at the edge |
| Polarizing film (surface) | Scratches through; spots lose polarization | Screen test shows patches |
| Polarizing film (laminated) | Does not age; sealed inside | Nothing |
| Hinges and screws | Loosen; arms flop | Glasses slide; screws visible backing out |
| Frame plastic | Goes brittle with years of UV and heat | Cracks at the hinge or bridge |
| Nose pads | Yellow, harden, absorb sunscreen | Discoloured and slippery |
| Tint | Does not fade in modern lenses | Nothing |
Notice what is not on the list as a real problem: the tint, and a laminated polarizing film. Neither fades or wears.
When to replace
Replace a pair when one of these is true, and not before:
- A scratch in your line of sight. It scatters light where you look all day. Our scratch post explains why it cannot be fixed.
- A coating is flaking. A peeling anti-reflective back or a patchy mirror will not stop.
- The frame no longer holds. Loose hinges can be tightened; brittle, cracked plastic cannot.
- You cannot verify the UV. For an old pair from an unknown source that you rely on outdoors, an optician's meter is a two-minute check.
There is no reason to replace a pair that is clear, intact and holds its shape, whatever its age.
What shortens a pair's life
Almost all of it is habits, and all of them are avoidable:
- Wiping a dry lens. The single biggest cause of scratches. Rinse first; our cleaning post is the method.
- Harsh cleaners. Ammonia, alcohol and solvents take coatings off.
- Heat. A dashboard in summer can warp frames and craze coatings. Our car heat post covers it.
- Loose in a bag. Keys and coins against the lens. A soft pouch is enough.
- Lens-down on a table. Grit under the lens every time.
- Pushed up on the head. Stretches the temples and coats the lens in hair product.
What a $34 pair should last
Treated well, years. The frame is plastic and light, the lens is laminated so the polarization cannot wear off, and the UV block is in the material. What will end it is a scratch or a dropped-on-concrete crack, not age. Every product page says what is known about the construction and what is not.
Frequently asked questions
Do sunglasses expire?
No. There is no date after which a pair stops working. Coatings can wear and frames can loosen, but a clear, intact pair protects as well as the day it was made.
Does UV protection wear off sunglasses?
Not if it is built into the lens material, which is the case for most modern plastic lenses. A UV coating applied to the surface can be scratched through or degrade over years. An optician can check any pair with a UV meter.
How long should sunglasses last?
Years, with a rinse before every wipe and a case when they are off your face. A season, if they are wiped dry on clothing and left in a hot car.
Do polarized lenses wear out?
A laminated film sealed inside the lens does not. A polarizing coating on the surface can be scratched through, leaving spots that are not polarized.
How do I know if my sunglasses still block UV?
You cannot tell by looking. An optician's UV meter checks it in seconds. If the lens material absorbs UV, which most modern plastic lenses do, it still does.
Sources
- American Academy of Ophthalmology. Do sunglasses expire? On UV coatings and lens materials. www.aao.org
- American Optometric Association. Eyeglass care and handling. www.aoa.org
Measurements on this site are the frame maker's published figures, attributed on every page that prints one. This is general information about sunglasses, not medical advice.
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