I had a pair once,made using safety glass frames. I did this at the time for peace of mind. An optometrist I know real well(enough to go shooting with), states that this is overkill. Sturdy frames with the new plastic lenses are good enough. I trust him to a point. Depending on the size of your frames, UVEX safety glasses work real well. I now use the tinted ones (gray), and I have seen "mirrored" lenses as well. These fit over my frames now nicely. Plus they are a lot less expensive than "Shooting Safety Glasses". I hope this helps.....................
Keep it safe
Joe
PS there are also a lot of good "shop glasses" out there made for slipping over prescription glasses