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Testing sunglasses at home?

  1. Feb 18, 2016 #1
    Is there an experiment you can do at home to test whether a pair of sunglasses blocks UVA/UVB wavelengths? It says total UV protection but that could mean anything and I don't want wrinkles.
     
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  3. Feb 18, 2016 #2
    http://www.allaboutvision.com/eye-doctor/

    "Not all sunglasses block 100 percent of UV rays. If you're unsure about the level of UV protection your sunglasses provide, take them to your eye doctor or optician for an evaluation. Many eye care professionals have instruments such as spectrophotometers that can measure the amount of visible light and UV radiation your lenses block.
     
  4. Feb 18, 2016 #3

    berkeman

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    Welcome to the PF.

    Sunglasses aren't for preventing wrinkles... :smile:
     
  5. Feb 18, 2016 #4
    that's the job of a [lotion] sunscreen or wide brimmed hat.
     
  6. Feb 18, 2016 #5

    sophiecentaur

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    The job of sunglasses is mainly to prevent cataracts and eye cancers, I think. Suncream can't do that and hats are only effective to some degree.
    If you happen to have a pair of 'transitions' sunglasses, you could use them as indicators of the presence of UV.
    But it's unlikely that you can do any valid experiment without the right equipment and the manufacturers are very shifty about giving any actual figures for performance. It seems that the 'UV400' standard is what's needed and that calls for 'total' blocking of all wavelengths below 400nm (whatever the word "total" means. I did a google search but I really couldn't recommend any particular link because they all seem to avoid putting in any actual figures and they're all from manufacturers. Funnily enough,I did find a source from eBay that seemed to say more than anything else I read.
     
  7. Feb 18, 2016 #6
    They are if they claim to protect you from UVA light, UVB is what gives you sunburn :)
     
  8. Feb 18, 2016 #7

    berkeman

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    LOL, he was saying to use sunscreen to help prevent wrinkles... :smile:
     
  9. Feb 18, 2016 #8

    berkeman

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    The point is they would only protect from wrinkles and sunburn in the small area around your eyes. They do not help where they cast no shadow (the rest of your face).

    As the centaur says, the eyeglass protection is for different issues.
     
  10. Feb 18, 2016 #9
    Exactly! I wear sunscreen all over my face and reapply it every 3-4 hours, but sunscreen would irritate the delicate under-eye area, which is precisely why, among other reasons, I want to wear sunglasses to prevent wrinkles.

    There are dermatologists who recommend wearing sunglasses for exactly this reason.
     
  11. Feb 18, 2016 #10
    I see, thanks.
     
  12. Feb 18, 2016 #11

    sophiecentaur

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    Sorry I can't be more helpful but, even if the blocking is not complete, they are a lot lot better than nothing.
     
  13. Feb 18, 2016 #12

    Andy Resnick

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    You raise an important issue, and the OP asks a good question. Sunglasses, because they reduce the amount of light entering your eye, result in a dilated pupil as compared to no sunglasses. Thus, dark sunglasses that don't effectively block UV light may actually lead to *increased* eye damage as compared to not wearing them. Same thing with ski goggles- if they darken the scene, your pupils dilate and more UV will enter your eye.

    The same principle holds with laser safety- you are safer doing beam alignment, etc. with the room lights on.
     
  14. Feb 18, 2016 #13
    I imagine you can use a black light to test whether UVA passes through enough to visibly detect the "best" protection of various glasses at least to some degree.
     
  15. Feb 19, 2016 #14

    anorlunda

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    That's correct. I was told that is the reason that I can't buy so-called blue-blocker sunglasses any more. Those were the ones with an amber or orange hue. They were very pleasant to wear, but they did increase dilation and thus eye damage. My suppliers say they can't sell them any more.
     
  16. Feb 19, 2016 #15

    CWatters

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    You can buy UV meters on eBay quite cheap. Including add on sensors for mobile phones. No idea how good they are.
     
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