I wear 1.75 diopter reading glasses. Last weekend I was shooting a rifle with a Leupold VX-2 scope, non adjustable objective. I happened to look through the scope and HOLY COW! a much sharper image of the target! I shot a couple of groups with the cheaters on and found them to be much smaller than previous ones with the same ammo.
I do not wear glasses for anything but reading and close work, my vision past 18 inches is still great.
Explanation?