Why can't I just get a pair of sunglasses that's dark enough?
I have tinted polarized wrapped sunglasses that are nominally 80% tint. I use them for driving and for flying and find that they are not dark enough for either. The old glasses are scratched and it's time for new ones. One local optician refuses to sell me anything darker than 80% and another says driving will be dangerous with a 90% tint. I've never owned a pair of sunglasses that actually relieved the squinting outdoors and suspect my eyes are more sensitive than most.