Frames: A form fitting goggle will offer the most protection, shielding the eyes from wind, dirt and debris. Lenses: To protect your eyes from dirt, rocks, and other debris, polycarbonate lenses are highly recommended for their impact resistance and durability. The lenses should also offer 100% UV protection. The lens color can affect how you see the terrain. For example, a brown based lens will provide the best contrast while a gray lens allows true perception with the least color distortion.