I'm 55, a Diabetic, and use tri-focal progressives (no lines). I have astigmatism & am myopic. I just won yesterdays' hand gun Match, beating-out (4) other revolvers & (5) percussion single-shots with my out-of-the-box Uberti Colt Walker. Yesterday the planets aligned and I could see the sights and the target by keeping my head straight and using the "tilting method" while holding the 4.5 pound monster perfectly still at the point of ignition.
For rifle sights, I use the old, traditional, drift-adjustable (with a block of pine & a hammer) primitive sight that Lyman supplies. One of the clubs I belong to is a traditional club, so adjustables have to be nail-polished to render them fixed. Front sight alignment is more important and I've learned to see enough of the back sight to be able to still cut cards in half, so I must be doin' sumthin' right, lol!
Best advice I can give is to keep yer head on a swivel & learn where your "new normal" actually is as far as head tilt while sighting guns. There's an "art" to doing it right & it takes some practice, but I'm living proof that said practice can accomplish a goal---like keepin'-up with the kids!
Hope you get your "new normal" soon!
All the best,
Dave