Your eyes are very busy doing a number of things -- multi tasking as it were. This good exercise for the eyes. In daylight my eysight is good enough to dispense with my prescription lenses. So I can wear all colors of wrap around lenses that claim to be UV-400. This includes a clear, uncolored lenses. Polycarbonate plastic itself apparently cuts the UV wave length, but coating improves performance. Anyway, using a UV-400 or better rated lens will help you to avoid cataracts -- a change in the proteins on the surface of the eye.