Older drivers with a 40 percent or greater impairment in their field of vision are more than twice as likely to crash a motor vehicle than those with better vision, researchers say.
Writing in the Journal of the American Medical Association, scientists at the University of Alabama at Birmingham's School of Medicine reported on their three-year test of more than 290 drivers aged 55 to 87.
The tests measured decline in visual sensory function, slowed visual processing speed and impaired visual attention skills. The report cited a recent population-based study that suggests approximately one in three older adults has a 40 percent or greater reduction in useful field of view.
Fifty-six drivers in the test incurred at least one crash in the three-year follow-up period, 11 of those experienced two or more crashes. The majority of crashes (70 percent) involved failure to yield the right-of-way, failure to heed a stop signal or misjudged stopping distance.
The authors suggest it is possible that older individuals who do not drive daily are also more likely to avoid driving in conditions that exceed their abilities. There is evidence that older adults who are aware of their visual processing limitations tend to self-regulate when and where they drive, avoiding the most difficult driving situations.
