In the past I've had sunglasses that came with 3 pairs of interchangeable lenses - dark for sun, yellow for cloudy/flat light, clear for dark. I found myself rarely needing the clear lenses, because these days I never ride at night when it's really dark out. Now with my new Oakleys (which I love love love), I have the dark polarized lenses for most daytime riding and yellow lenses for when there is no chance the sun will come out or when it is dusk.

I did get caught in a heavy rain during a ride last year, and I got so wet that I was blinded by the rain even with the sunglasses on - water ran down my forehead inside the lenses. Luckily I was on a rail-trail and not far from a covered rest area when it happened, so I was able to take cover until the storm passed. I think that's the only time that glasses failed to keep rain out of my eyes, and I did the Sea Gull century in a nor'easter once.

Now if only the sunglasses would keep pollen out of my eyes, they would be perfect.