I had the same problem. I've done several experiments with different producats (as well as other people with the same problem), until we found some scientifically done tests done by some very well known mountaineering magazine. We discovered that there is only a producer in the world that builds glasses for specifical aeronautical use. It is Carl Zeiss, which produces the Clarlet Skylet leneses (available also with correction). They come in three different grade of tint (all brownish). The useful is the Sport model, the darkest with 10% light transmittance.The lens is build in plastic (so no problem in whack case...). The lenses need to be fitted in a frame (already complete glasses are not available), and are non-polarizing. I've verified directly with Carl Zeiss technicians before buy the lenses, discovering that they are a standard that they devloped originally under request of several airlines for their pilots, and finally decided to buy them with the Carat treatment (extremely anti-scratch and anti-reflection performance), which raise the prices quite high (Carl Zeiss product = bet quality and price

. The result is that almost everyone tried my galasses bought one for himself/herself. No doubt that they are the best in class, but not suitable for who tends to lost often the glasses, due their price. It is an investment destined to a very long time use.
For more info take a lok at:
http://www.zeiss.de/zeiss/english/home.nsf/frame/
cop_glasses_sun_skyl...
http://www.zeiss.co.uk/opttecoat.htm
My 2 cents.