The peripheral vision is a problem. He is blind in his left eye. When making a lane change from the right lane to the left lane he must turn his head all the way to his left shoulder to make sure nobody is in his blind spot.
As for depth perception, when traffic is slowing up ahead of him or at a stop, without depth perception, it is very difficult to judge the amount of space between your car and the car ahead of you. Trying to judge the slow down rate of the car ahead of him is very difficult and has almost caused an accident.
Because I don't have any vision problems, I was not quite sure how his vision affected his driving, so I did ask him. Likewise, with just one eye, it is much more intensive and tiring. Much more head turning and requires much more concentration.
He is looking for a new car that can assist him as much as possible with driving. And yes, a person with just one good eye can obtain a drivers license.