I'm lucky that my vision in that my vision is stuck in a place where I need bifocals, but I'm functional without them, except for driving. I keep a pair in my coat, a pair in the Jeep, a pair at my desk and a pair in my BOB, along with a repair kit in all my kits. I lost one lens while hiking this summer, and learned my lesson well.
Sunglasses are crucial for me too, especially when there's snow glare outside.
Getting old sucks!