As a 50 something PPC shooter I had sight focus issues as well. Like the other posts I went to my eye guy and had my exact distance measured (make sure your Dr. is cool with bringing guns into the office).
I have a hybrid set of "Executive"(frame style) bi-focal lens. The entire top half is magnified (both lens) for close and bottom is for distance.
To aim,a slight lowering of the head (a nod)and the sights are clear. This works in all positions. Look straight ahead and I can see the target and confirm hits. It doesn't affect balance when moving as the one eye set-up did to me. Works great in action shooting events too.
It took nearly 2 years of experimenting to find this combination, but it works great for me. Good luck.