Though I'm only 51, my inner ear and balance has become a bit dodgy in the past year or so. I switched to a recumbent trike. Without it I probably would have been off the bike indefinitely. I used to ride pell-mell everywhere on my ten speed, but now I take my time, and that is easy on a three wheeler. Even on days I am not feeling my best, I'll go on a short ride on the path, and avoid the streets. Better than not riding at all. On my good days, I'm out and about on the trike for hours. I hope to be able to pedal right up to the last day of my life.
I have a handlebar mounted mirror on the right side, and a mirror on my sunglasses. Very helpful, since a lot of cars nowadays don't make much noise as it is.