The literature, though, is rather inconclusive on this subject. For every study that shows a link between crashes and a medical condition, there is generally another study that shows no association. Overall, most evidence seems to suggest that there is a link to lower visual abilities. After that, it gets problematic.

The next three slides illustrate the data from a case-control study by Koepsell, et.al. It is one of the better studies in the area. Shown here are the data relating to cardiovascular disease and crashes. No associations were observed.

Source: Koepsell TM, et al. Medical conditions and motor vehicle collision injuries in older adults. Journal of the American Geriatrics Society 42:695-700, 1994