I'm far-sighted and it has gotten hard to have the rear sight on rifles (and pistols) in focus.  I wear 2X readers for reading, writing, and doing close work (and seeing the computer screen).  I have saved my older readers, 1X, 1.5X, and 1.75X with safety lenses.  I discovered a couple of years back that they make good shooting glasses and bring rifle and pistol sights into good focus.  The distant bulls-eye may be a bit fuzzy and out of focus but this does not impact accurate shooting.  I prefer iron sights and this use of old 'under-powered' readers works for me.