Why do some sunglasses make everything seem lighter?

Question

Why do some sunglasses make everything seem lighter?

Answer 1

Your eyes adjust to the light but some can actually increase sharpness.  They do this by filtering a certain color which reduces the chromatic aberration in the lens.  You would have to have really good eyes to notice it.  Some of them block the blue haze and it may seem clearer.  That probably seems lighter since that is one way you are used to judging brightness.