Bifocals are a 'no no.'

Bifocal glasses and the golf swing don't match.  Whenever I have a student that has glasses on, one of my first questions is if the glasses they on have a bifocal lens.  If they do, the student is at a severe disadvantage in being able to make a correct golf swing.
When a golfer plays with bifocals they have a very limited window in the bottom of their lens to see the ball. As a result the head is looking straight down with the appearance of the chin being buried in the chest.
The golfer's main goal is to make sure they never lose sight of the ball throughout the entire swing.
I recommend they get a pair of 'sport specific' glasses the next time they visit their eye doctor.