I was watching I believe the Today Show on NBC talking about harmful effects of UV on the eyes. The Ophthalmologist was explaining the need for a good pair of sunglasses that blocks UVA, UVB. She said that not all sunglasses block UV, and you don't need a expensive pair of sunglasses to block UV. I have a BPI photometer and when I tint a pair of #3 gray sunglasses (CR-39) that I didn't UV, I still get almost 0% uv transmission.
Please explain to me why you need to uv cr-39 and then tint it #3 gray.
Jeff
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