Last month's tragedy in Santa Monica, Calif., where 10 people died and 40 more were injured when an 86-year-old man lost control of his car and rammed a crowded marketplace, raised awareness of the challenging issue of driving privileges for older drivers. By now, the media coverage has likely faded, as has general interest in the topic—until the next time, anyway.

Physicians know and researchers have proven that withdrawing driving privileges not only affects the individual's lifestyle but can also take a serious toll on emotional well-being. Older drivers are not disproportionately more likely to be involved in accidents simply because of age. The rate of crashes per mile does, however, begin to rise at age 70, and increases rapidly at age 80, according to the National Highway Traffic Administration. Older drivers who are in crashes, though, face dire consequences: They are 3.5 times more likely to die from injuries in a car crash. And by 2020, there will be three times as many drivers age 70-plus on the road as the 13 million today.

Impaired vision apparently played no obvious role in the Santa Monica accident. Vision is, however, one of the major areas of concern when considering seniors' driving privileges. What's surprising is how few states require any kind of reassessment of vision based on age. Just four states do so, according to the Insurance Institute for Highway Safety. Last month, Florida enacted legislation requiring drivers age 80 and over to undergo vision testing when their license renewal comes due. Eye doctors in that haven for the elderly will soon be administering vision tests that may effectively take the keys away from many older drivers. It's not hard to foresee other states following Florida's lead.

There is far more to this discussion than vision assessment, and there are far more difficult decisions and choices ahead than simply when to take the keys away.

The sad reality is that our roads and our cars are not designed to handle the needs of older drivers. Our public transportation systems are not equipped to handle the mobility needs that remain when a senior's license is pulled. And the swelling ranks of older drivers will very soon make this an issue we can no longer ignore.