It is a problem. Five years ago, my father-in-law gave up driving because of slowed response time and age-induced macular degeneration (since stabilized). My mother-in-law (87) will NOT admit to lessened capacity, but fortunately she hasn't driven at night for many years.

I'm soon to be 61, my wife is 63. We're both going to take refresher courses the next time they're offered.

I think that after, say, 75 or whenever in the opinion of a license examiner your reflexes or other physical or mental functioning has slowed down you should be re-examined and if necessary given a restricted license (of it should be removed entirely). Re-testing should be mandatory every three years -- and if you stop or are stopped driving free public transportation should be made available.

(As a paranthetical note, the best driving course I ever had was an informal one-on-one by a pursuit driver for the Ohio State Police. He taught me things I never knew could be done -- legal, and which enhance safety at any speed (I never drove over 110 mph on the course). The second best was a cross-country driving course taught by the US Army -- my driver's education classed in high school were a joke.)