Here’s a possible solution that competition shooters use, mostly smallbore, but others do too.
They are called Knobloch’s. The only source I’ve ever seen was champion’s Choice.
The lens are sold in many magnification powers.
The main idea is that you adjust the lens so you are looking straight, perpendicular, through the glass and not on an angle like when shooting off the bench and your head is angled which makes your glasses angled so that you are looking through the glass at an angle. Not only that, but your glasses may not consistently be looking through the same magnification portion of the lens. The Knobloch’s correct that problem.
Randy
View attachment 277110