I believe that when drivers reach a certain age they should have to take a behind the wheel test and a eye test yearly. In the latest issue of Newsweek theres an article about an elderly woman who has macular degeneration, (which blurs vision) who was still driving when she really couldn't see much. I have experienced this first hand, my 85 year-old grandmother also has macular degeneration and was driving when she shouldn't have been. She thought she was a fine driver too, but in reality she couldn't see much at all and the only way she got around was just because the places she went were familiar. She was a danger to herself and everyone else on the road. We had to forcefully take her keys away from her and she is no longer driving. There are lots of other elderly people on the road just like her and the only way to take them off the road is by family members or friends. The government has no way to take these drivers off the road expect for eye tests, which are like every 5 years or so. Heres the Newsweek article:
http://www.msnbc.com/news/934701.asp#BODY