AFAIK, shooting glasses have the optical center cut in a different part of the lens from your typical reading or driving glasses. With reading glassed, the optical center, where your eye will spend most of its time looking through, will be in the center of the lens.
Typically, when you shoot rifle or shotgun, you will have your head tilted and you'll be looking through the upper left corner of the right lens (if you're a right handed shooter). The lab has to grind your optical center in that location. If you shoot pistol, you may or may not look through the same area.
It's important to put on the pair of glasses and imitate where you would be holding your head and where you will be looking through the lens. Have them mark that area on the lens, so they know where to put the optical center.
In my case it is the upper left part of the lens of my right eye. In that area, when I look through the lens, everything is crystal clear. However, when I'm driving home from the range and I haven't taken the glasses off and replaced them with my normal glasses, the instrument cluster and road are blurry. It's very disconcerting.
In my experience, shooting glasses cannot be used as every day glasses. My shooting glasses are far superior to my normal reading glasses at the range or hunting. When I've left my shooting glasses at home I find it really frustrating to shoot as things are a little blurry.
And I got my shooting glasses at Wallyworld. I picked up some big aviator frames and had them put in untinted polycarbonate lenses. Cost me $90.
