
Originally Posted by
qwertysaur

Originally Posted by
NorthernChaosGod

Originally Posted by
qwertysaur
if your sunglasses are not made to block UV, then they are going to actually cause more damage to your eyes. 
How so?
Mine are UV400 or whatever, according to the ebay listing.
Sunglasses are made so less light in general goes through them. Your eyes will react by enlarging the pupils so they can take in as much of the limited light as they can. However if the sunglasses are not able to absorb UV light as well as visible light then the same amount of UV that would normally get to the eye still gets there, but now it has a larger area where it can hit. Prolong exposure will result in damage to the eye.
The more dangerous UV light doesn't pass through glass. That's why you don't tan easily through glass windows. Glass filters about 97%.
And this point is moot anyway, seeing as nearly every sunglasses available has UV protection nowadays, no matter how much it helps.