It is a problem with no easy answer. I work with my mother. She has been a good driver all her life and wants to continue. Driving at night is a no-no. We work out her routes to avoid the bad areas. Make three right turns and a left at the light instead of having to make a left across fast moving traffic where there is no light. Shop at Kmart instead of Walmart since the parking lot is so empty!
My dad was a great driver all his life, never had an accident that I can recall. It meant absolutely nothing in the end; he was playing russian roulette with his own neurology.