I have half a dozen pairs of these Serengeti sunglasses, they are very comfortable on my eyes.  Before I switched exclusively to the Serengeti glasses, I'd get headaches almost daily.  My eye doctor said it was from cheap sunglasses.  He said my eyes were working very hard to correct the issues in the lenses.  Sure enough when I broke down and paid the money for good optically correct lenses, my headaches went away.  The other thing I like about these lenses is no matter the brightness of the sun, overcast, rain, fog, they still give me better vision than without them.

Negatives;
1.) I can't read my GPS well with these on.  I have to remove them to read electronic screens.
2.) They break easy, handle them with kit gloves.