I agree about demand being on your eyes. Sometimes when the light is just right, I'm amazed at how well I can see... see to wade (in the smokies without stepping in a hole and breaking an ankle) see the fish, etc. Then the light changes or I move up to the next pool and can't see crap for the glare. The same thing happens in the evenings, as it nears dusk. I go from being able to see ok to nothing but glare.
Maybe I've been a good enough boy that Santa claus will bring me some glasses...