Zenni Optical - Complete prescription eyeglasses from $8.00 I'm thinking of ordering some for biking. But I'm concerned that they aren't available in bi-focal and that the "windscreen" isn't polarized. Will I miss those features? It also seems that the tint on the windscreen isn't very dark. Or is it dark enough? I could order a tinted lense for the glasses, but I don't want to overdo it.