My only concern would be "changing colors". The lenses aren't green indoors and blue outdoors, or brown indoors and purple outdoors. Somehow "changing colors" makes me think of a variety of colors rather than a lighter/darker difference because of tinting.
I agree with James M. The lenses do not "change color"; they "change" or "adjust". It also is not "different environments" that makes them adjust, but different lighting conditions. I would tend to say "They become darker in bright light."