I wear prescrip glasses and have a pair of sunglasses.
Not ordinary sunglasses, but seriously dark sunglasses. I can see well enough for any daytime situation which includes covered bridges and tunnels, but they're darker than any regular sunglasses.
The optometrist originally thought I was nuts when I told them I wanted them seriously darker tint, but once he took them outside and looked up toward the sun he changed his tune. I can ride into the sun with the tint we do, without squinting. I've only seen one pair of sunglasses that dark - a cheap pair that Wendy's used to either sell for a buck or give away. Never seen any Oakleys or tinted shields that good.
I just ordered another pair in the newer wrap around style so I can wear them with my dual sport helmet running shield open, yet still have good protection near goggle level. The technology now allows a prescrip grind including bifocal on the more radical curved lense of a wrap around. They ain't cheap, about $250-300, but it will be worth it. The sealing valence around the frame that makes them fit snug is removable for general use too.
It only takes me about 30 seconds to change glasses if I need to do so. I can do it sitting on the bike at the side of the road quite easily. But I also wore them when shopping and stopping for lunch the other day, so even as dark as they are I can still use them indoors if needed.
So if you're a glasses wearer or are willing to spend the money for glasses with custom tint, getting a pair of glasses with very dark tint is a good option. They can change tint too if needed, you can go darker if not as dark as wanted.
One side note. We also did a trick with my bifocal grind. I do regular "lined" bifocal grind because I want maximum in focus distance. For the motorcycle use we actually dropped my near sight grind. It falls right at the instruments with everything above being in the distance grind. Works great.