Darkness, with sun

I recently got some new glasses that get darker in bright light. Now, even when it's sunny, my world is gloomy. The sunlight comes in round the edges, so I'm permanently half-blinded and can't gauge brightness. When I cycle from sun to shadow I can see nothing at all in the darkness so I risk crashing into other people. And worst of all, I can't see through the viewfinder to take pictures.

Has anyone else had these problems? Is there a solution, other than taking the glasses back?