Casco lenses absorb up to 100% of eye damaging UV-A, B and C rays. UV-C (-290nm): is absorbed by the earths ozone layer and our filters.  UV-B (-315nm): causes the skin to tan or burn and can cause conjunctivitis and even snow blindness. UV-A (-400nm): effects a mild tanning of the skin and can lead to cataracts when the eyes have been exposed to its rays over many years