I have a pair of Varilux Safety glasses, bought for me by my previous
employer's (Weatherford)
buy-you-one-pair-of-prescription-safety-glasses-every-two-years plan.
I find that they are wonderful wear-in-the-store glasses, or go to
meeting glasses, but when you are working on mechanical things...
straight lines are curved, you have to wiggle your head around all the
time to focus, you have to point your head at the moon to focus on
something really closely.

No good for the mechanical type. Back to the dollar store glasses.
Cheap, throw them away when they're damaged. I'll keep the Varilux for
family reunions, looking for the Cereal boxes etc.