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July 14, 2006 9:45 PM   Subscribe

Do cheap sunglasses protect you from the sun at all?

It's seems to me to be a given that, despite whatever the stickers on my 15 dollar Target specials say about UV protection, cheap sunglasses probably don't do jack. Any chance I'm wrong?
posted by BruceL to Health & Fitness (15 answers total)
Best answer: You'd be wrong; cheap sunglasses work pretty well for providing UV protection. They might have other optical flaws, but they do block harmful UV.
posted by paulsc at 9:55 PM on July 14, 2006

They would at least keep you from squinting and getting crow's feet.
posted by sweetkid at 10:05 PM on July 14, 2006

The absolute cheapest glasses can do more damage than no glasses at all. I'm talking $5 and under glasses that usually don't have any UV protection at all -- they do more damage by being dark and opening up your retinas a bit, but letting all the sun's rays into them, which is worse than if you took them off and squinted.

But this is only for UV-less non-coated cheapies you might find at a county fair.
posted by mathowie at 10:21 PM on July 14, 2006 [1 favorite]

Best answer: Back when I worked in a lab I ran a couple of my cheap $12 sunglasses through the UV spectrometer and checked the absorbtion spectrum. All of them blocked in excess of 98% throughout the UV range.

And, just for the sake of anatomical accuracy, its your pupils that open and close. Your retinas stay attached to the back of your eye (hopefully).
posted by Good Brain at 10:25 PM on July 14, 2006 [1 favorite]

Well, Ive always felt the real problem is with tinted glasses being sold as sunglasses, with the cool packaging and all the necessary [fake] labeling to get you to buy them. And there are a number of them around, especially the ones made in China, with brand names changing with the flavour of the month.

That said, if an optician certifies them, as suggested in the link by paulsc, you've got a bargain -- buy a dozen for your friends. I would.
posted by metaswell at 10:29 PM on July 14, 2006

and its the iris which defines the pupil
posted by Good Brain at 10:31 PM on July 14, 2006

You can sometimes find inexpensive sunglasses that are UV proof and also polarized, so they cut reflected glare from water and glass (sun glinting off the back window of that car you're following). Very easy on the eyes.
posted by weapons-grade pandemonium at 11:37 PM on July 14, 2006

Oh, and neutral density is nifty--the colors are dimmer, but all hues are otherwise realistic.
posted by weapons-grade pandemonium at 11:40 PM on July 14, 2006

In Australia, there's a standard for sunglasses - if a pair of sunnies has the standards label, then it'll block UV and be safe for your eyes, no matter how cheap they are. My current sunnies are polarized glarefoils - AUS$20. Is there something similar in the US?

My brother told me a story once about some mates in Thailand who bought cheap sunnies. Didn't do anything except cause their pupils to dilate, which let in even more UV and made them temporarily blind.
posted by obiwanwasabi at 2:20 AM on July 15, 2006

Best answer: Those stories about dark glasses making pupils dialate without blocking UV are usually old stories from back in the day when glass lenses were cheaper to make than plastic ones. Glass has no inherent UV blocking property. It needs to be coated or treated to block UV.

Fortunately, plastic lenses for sunglasses are now cheaper than glass ones, so the $5 sunnglasses you see are almost all made with plastic lenses. Plastic of the type used in sunglasses is inherently UV blocking. Saran wrap blocks quite a bit of UV. The plastic in sunglsses is quite a bit thicker and more UV blocking. So, the cheapies are almost sure to be safe.

Also, keep in mind that the UV blocking ability of the glasses has essentially nothing to do with how dark they are. There are lots of reputable sunglass companies out there that make clear or nearly clear plastic sunglasses. (Mountain bikers like them for keeping flying dirt/bugs out of their eyes when they're riding through densley wooded areas.) These clear lenses are 98%+ UV blocking.

Some people are also concerned about blue light exposure. Blue is next to UV on the light spectrum. Some manufacturers list blue light transmission when describing their lenses. Brown lenses tend to be better in this regard than grey (neutral density.)
posted by thenormshow at 7:36 AM on July 15, 2006

These answers have been very interesting and informative. My husband and I are in the cheap sunglasses business. We live in a beachside tourist town, and sell sunglasses for a living. We have lots of customers asking the same question, and we assure them that they do block UV light.
posted by LoriFLA at 8:09 AM on July 15, 2006

Sorry but, Glass has no inherent UV blocking property, just is not true. It's blocks UV quite well.
Here's an "Ask the Scientist" that talks about it.

How often have you been sunburned through your car windows? In fact I remember in one of Richard Feynman's books he told the story of watching the first atomic bomb test while sitting in a pickup truck, so that the windshield would absorb any UV rays from the blast. (Well, although now that I think about it, modern cars have safety glass which has a layer of plastic in it.)

For sunglasses, not only is plastic cheaper than glass, it's safer: it doesn't shatter into small sharp shards.
posted by ShooBoo at 8:27 AM on July 15, 2006

No professional answer, but I know my cheap $15 sunglasses from a pharmacy that claimed UVA and UVB work wonders in terms of reducing glare and keeping me from squinting - my eyes no longer feel tired and weak after long drives.
posted by criticman at 10:05 AM on July 15, 2006

How often have you been sunburned through your car windows?

Er...enough that I now wear sunscreen when I'm driving in the summer.
posted by kittyprecious at 10:27 AM on July 15, 2006

Response by poster: Awesome; I dedicate this flex of my well-developed crows feet to you all. Thanks for the replies, it's freed me from the shackles of $200 shades and released me upon a new world, one that is full of pink lenses and gold rims and will only cost $11 a pop to stretch my horizons.
posted by BruceL at 6:47 PM on July 16, 2006

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