If medical conditions arise his license can be revoked.
I am only 50 and I have an internal defibrillator. As of right now, I can drive but if I lose consciousness at any point from one of my arrhythmias they will take my license (as they should).
So if their eye exams come back poorly, or they develop certain heart conditions, have a stroke, have dementia or Alzheimer’s, their license can be revoked.
I am really praying for autonomous driving cars.