Many cheap sunglasses claim that they block 100% of UV rays.  How do I
know if sunglasses really do protect my eyes without paying lots of
money for the brand names?  For example, the following are knock offs
of designer brands... but how do I know if their claims of protecting
your eyes really are true?

http://www.amazon.com/gp/product/B000APSZNY/qid=1145565883/sr=8-16/ref=sr_1_16/104-1068398-6787932?%5Fencoding=UTF8&v=glance&n=1036592

http://www.amazon.com/gp/product/B0002Y2JZI/qid=1145592195/sr=1-1/ref=sr_1_1/104-1068398-6787932?%5Fencoding=UTF8&s=apparel&v=glance&n=1036592

http://replica-eyewear.com/detail.asp?PRODUCT_ID=6057

Thank you!

Good luck with an official answer.

There's no demonstrated correlation between high prices and increased
UV protetection. A 1995 study reported that "Expensive brands and
polarizing sunglasses do not guarantee optimal UVA protection." The
Australian Competition and Consumer Commission has also reported that
"[c]onsumers cannot rely on price as an indicator of quality". One
unscientific survey even found a $6.95 pair of generic glasses with
slightly better protection than Michael Kors or Salvatore Ferragamo
shades.

Just because a glass or plastic blocks visible light doesnot mean it
does or doesn't kill higher or lower frequencies. (infrared or ultra
violet)

If your sunglasses do not clain to block, It is possible more damage
is being done. The eye maybe more open then it would be without the
sunglasses.

Yeah, I agree with both of you... that's why I'm just wondering how
you verify the claims that are made.  Thanks!

http://www.straightdope.com/classics/a990806.html

Above is a clear concise explanation. 

As an aside, Safety equipment companies sell OSHA approved eye
protection for pennies.  They are very cheap to make.  Expensive
sunglasses are all logo and fashion.  Same cheap UV coating on the
lenses.

The sun is something wonderful and healing. The only time I use
sunglasses is so I can cheat at fishing(expensive sunglasses) so I can
see the fishies or when visibility is so poor on a sunny day that I
can't see traffic very well. I believe most of what is said about UV
protection is bad science. For 90% of the people, they do not get
enough sunlight. Sunlight can cure depression, heal cancer, and feed
the soul. Cutting off one portal through the eyes with sunglasses is
just one more diconnect from good health. Gaze on a sunrise or
sunset...right into the flames and it will not hurt you...