DW> Yes. But almost all common glass and plastic lenses, even if they look
 DW> very clear in visible light, are strong absorbers of UV. There are

I understand that.  Which is why we used salt crystals for IR
spectoscopy.

 DW> several advantages to having to wear eyeglasses. One is that they can

As I have done for over 50 years.

 DW> protect against bits of grit or other material that could get into the
 DW> eyes. Another is that, even if you are unaware of it, they
 DW> substantially reduce your eyes' exposure to UV, and therefore the risk

But just as "colored" substances in the visible spectrum show a
selective absorption sprectum, UV absorption is a function of
the frequency--and it can vary substantially.  I've seen the
spectra.  Chemists use them for qualitative analysis.

 DW> of developing cataracts, and so on. Sunglasses that are specifically
 DW> designed to protect against UV do a better job, but not greatly so.

Mine have been specifically checked, and they are as absorbant
as they can be--the same level the USAF uses for pilot visors.
And they are very dark.

 DW> Contact lenses are also protective. Having your vision corrected by
 DW> laser surgery destroys the benefits that glasses or contacts provide.

But that bit of grit you mentioned can do real damage to one's
corneas.

Paul Rogers, paulgrogers{at}yahoo.com                       -o)
http://www.angelfire.com/or/paulrogers                   /\\
Rogers' Second Law: Everything you do communicates.     _\_V

... What you say will be misquoted and used against you.
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