Protecting your eyes from the sun

With the sun’s rays getting stronger and the days getting longer and warmer, the outdoors are calling out your name and telling you to come out and play. I believe that outdoor exercise is generally more beneficial than indoor, so this is a good thing.

However, one of the biggest downsides to outdoor exercise is the damaging effects of sunlight on the skin and eyes. Lack of proper eye protection can lead to permanent eye damage in the long-term, besides hindering athletic performance in the short-term. Luckily, all you need is a good pair of sunglasses to protect your eyes – with all the choices out there, choosing the right one can be difficult.

Here are some tips to help you choose the right glasses to maximize eye protection:

1) Make sure they cover up enough of your eyes. Very small circle sunglasses may look “hip” to some people, but they don’t block enough sunlight from the side or the top. Wrap-around sunglasses are your best choice, since they block sunlight from all directions.

2) Make sure they provide enough darkening for very bright sunlight. Polarized glasses may be better for reducing glare and seeing things in water when the sun is out, but they are not absolutely necessary. Brown-orange lenses are probably the best color, along with brown-red, and brown-yellow. Grayish lenses are good as well. Pure red, green, or blue lenses aren’t a good idea since they can distort your vision.

3) Make sure they provide 100% UV light protection. This is different from how dark the lenses make your vision. Even some dark lens sunglasses can provide poor UV protection while some lighter ones provide 100% UV protection. UV light can damage your eyes over time, leading to macular degeneration and other serious problems.

How can you tell if your sunglasses provide 100% UV protection? One important thing to keep in mind is that price is no guarantee of UV protection. I’ve tested very expensive sunglasses and realized they provided little UV protection(even though the labels claimed they provided 100%), while some relatively cheap ones($8 to $25 U.S dollars) provided 100% UV protection.

How could I tell? There is a relatively simple trick you can do if you have access to a UV flashlight. There are some inexpensive UV flashlights available online if you are really interested in testing your sunglasses. Or borrow one if you can(do not beam it into your eyes). Here is what you do:

Go into a dark room with the UV flashlight, the sunglasses, and with paper money and/or a credit card. Turn on the UV light and beam it on the paper money. You should notice all these mysterious symbols on the money(usually a line) or credit card(usually letters) you normally wouldn’t see in ordinary light. These are watermarks used by banks and government officials to detect counterfeit money – these lines and/or symbols are only noticeable in UV light. Don’t worry, you are not doing anything illegal!

IMG_1004

Now take the sunglasses you wish to test, and beam the UV light through one of its lenses and onto the money or credit card.

– If you still see the symbols on the money or credit card, your glasses do not provide 100% UV protection(the lenses are letting through the UV light and revealing the symbols).

– If you do not see the symbols, your glasses have passed the test and do provide 100% UV protection – the lens blocks the UV, hence you can’t see the symbols.

I’ve done this test many many times over the years, and discovered that many expensive sunglasses belonging to friends and family(so disappointed!) do not provide 100% UV protection while some inexpensive ones did provide 100% UV protection. Granted, many expensive ones do provide 100% UV protection, and some cheap ones do not, but do not let price be your guide. And unfortunately, there is little regulation of sunglasses and labelling can be dishonest.

If the glasses fail the test, make sure you return them and get a refund as quickly as possible. If it’s at all possible, see if you can even test sunglasses at the store.

Now get out and enjoy the early spring!

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6 responses to “Protecting your eyes from the sun

  1. That is so interesting! Thanks!

  2. You’re welcome. I’m glad you found it helpful.

  3. Splendid! This trick actually works. It also works for a blue laser, but of course it doesn’t give exact values on UV protection, it at least tells me that my glasses offer good UV protection!
    Thanks a lot, Helped! I used normal specs for this though.

  4. I am kind of think out loud, but I wonder if this trick actually tests in the UV spectrum you want protection from. I’m guessing the watermarks are meant to be seen under a black light, which emits UV rays harmless enough that every college freshman has them constantly bombarding their naked eyes.

    I would be more inclined to not consider a pair of sunglasses certified as giving UV protection until you can show via some kind of test that it is specifically filtering out lower wavelength photons- like 400nm or less.

  5. Most of the Amazon flashlights are 395 nM.

    Is this a good wavelength for testing “UV400” defined as “This includes those labeled as “UV 400,” which blocks all light rays with wavelengths up to 400 nanometers. (This covers all of UVA and UVB rays.)”

    Or is a broader spectrum needed? Thank you.

    • Hello John. I am not really sure, but I think a broader spectrum would be better. Keep in mind, this is a rather crude possibly not very accurate method of testing glasses. It would be best to test glasses at a glasses store or lab if possible, but if that is not possible; the method recommended in the post is for people who don’t have any other way to test their glasses. Happy holidays!

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