Consider getting the new Knobloch or "Jagger" glasses from Champion Choice orChampion Shooter supply, then talk with your eye doctor about setting the :dominant eye to fcus at the nominal distance that your front sight will be, as measure from yout eye to the front sight. Have recent ly re adjusted mine to focus @ 36 inches.

For regular glassed consider rotating the close-up bifocal, ninety degrees, as this will minimize rolling your head back to use the bifical lens.
I was shooting a league with a revovler [only one of two] as the distance increase, the RO indiacted that before his retirement as a LEO, he rotated the bifocal to vertical from his nose to almost mid-point, but it allowed him to use his sidearm eaasily for firing.