I have these Guard-Dogs Flexor goggles that I bought in a bike shop which came with grey lenses. I'm wondering what is the light transmittance of these lenses. I've read on Wikipedia that the recommended light transmittance for prevention of snow blindness is 5 to 10% but also read that it's actually the UV rays that cause the damage. These lenses are 99.9% UV protection.

Their snow pack comes with "plum mirror" lens which makes me ask another question, do mirror shades (commonly known as cop shades) have a lower light transmittance and what about the plum color?

I already posted about silk neckerchief and found a justification for choosing the black color. Can I make suitable emergency snow blindness goggles out of a black (for maximum absorbtion) silk neckerchief by cutting slits?

Thanks

Frankie