Here is another take on this subject.
I took my CCW class with an eye surgeon up in Denver. He once wrote an article for the NRA magazine addressing this exact subject.
As we get older we lose the ability to see things nearest to us. We never could focus on the target AND the sights. Remember, sharp front sight, target a blur. Most bifocals are set for 14-22 inches, the front sight is usually 32 inches away. Thats why bifocals give a blurry front sight.
His solution is this, and this is what he offers to this date. He will fix you up with a prescription for a set of single vision shooting glasses focused on the front sight for the dominant eye. This gives you a wide field of vision. You bring your piece to his office and he gets the prescription down so that you see the front sight razor sharp. Then you get the glasses and you see the sights like an eagle. :>)
So, if you live in Colorado, and your eyes suck, you have an option.
Dr. Larry Krieder
Denver Eye Surgery Center
For the rest of you, find a shooter friendly eye guy.