I have a pair of glass Costas in blue and one in green polycarbonate. I have worn the blue glass one far more for daily use and after 3 years still have no scratches. The green plastic lenses scratch much easier. I only use them while fishing. They would never make it 2 years the way I treat glasses. On the water the blue lenses do a bit better for cutting glare off the water making it much easier to spot markers but the green ones have much better contrast when looking down into the water.