UV rays and the eye

Mentallic

It's simply common sense that looking directly into the sun is a bad thing, but what about with your eyes shut? I'm unsure if the UV rays can penetrate the eyelid, or at least if they can, if a significant percentage of the rays get through.

Is it a factor to consider when tanning for over an hour in the middle of a summer's day without sunglasses on?

Andy Resnick

It's an interesting question, but don't forget to apply sunscreen to your eyelid.

I couldn't find any reliable data on the UV transmission of an eyelid, but skin appears to be highly absorptive:

http://www.online.karger.com/Produkt...oduktNr=224164

Mentallic

Is the sunscreen on the eyelid directed at protecting the eye further or the skin?

I've also heard that the eye is very resistant to ultraviolet radiation - but then again, this could just be a rumour and it also seems counter-intuitive since our natural reaction is to squint when looking at the sun. This squinting process is most likely because of the intensity of light being too high though.
There is a big emphasis on wearing sunglasses that protect against UV light as well. Back in the day this wasn't a factor many considered important so in essence they wore glasses that blocked out the visible light but let the UV through. This meant you weren't squinting like you normally would so more UV would reach the eye. Are there any confirmed short-term or long-term consequences as a result of this?