I shoot with my progressive bifocals. I just don't use the bottom part. I focus on the target. The front sight is just a bit out of focus and the rear sight is way out, as it always has been.
I tried working out some kind of system with getting the sights aligned with the glasses, but I couldn't every find any way to do it that was comfortable. I did put peep sights on a couple of lever rifles and my Garand came with one. Those help immensely. The front sight is still slightly fuzzy, but it's very easy to put on the target.
To be honest, I can't stand my bifocals and, next time I get over to the optometrist, I'm going to ditch them and go back to single lenses. I'll just use reading glasses for close up work, like I did before.
Well we don't rent pigs and I figure it's better to say it right out front because a man that does like to rent pigs is... he's hard to stop - Gus McCrae