What about the light that DOES get in? What about the lens the light passes through? I assume you're an eye doctor...but google returns about 1.6 million hits that might state otherwise (I don't have time to check them all...but here's one).
http://www.gatewaysafety.com/safety-...p?ResourceID=4
The light that gets in is so insignificant that it doesn't matter, unless you're actually staring at the sun, in which case you deserve to go blind. And I'm not an eye doctor, only a college kid. It's amazing what you learn in school.
And when you link sites, choose a credible source, not ones trying to push a product. I recommend .edu and .org sites.
QED