I don't know about you but my vision problems get very much worse in the heat, and my mind turns to mush too. I sometimes wonder if I'm overdoing my dislike of heat when I cross a street just to get to a bit of shade on a hot day, then cross the same street again to find a bit of shade on the other side.

Then I remember what heat does to me, and I don't have to be in it long at all.<---sunglasses somehow make it seem a bit cooler

<---wearing a hat is supposed to help too but the hat itself is hot though the brim does create some shade.