Driving While Dilated
This could be due to the fact that over half of the drivers appeared to compensate for the deterioration in their vision by adjusting their driving, including reducing their speed, which improved steering accuracy.
"They did the same on the driving test, which, in essence, is what is important," says Varma. "I mean, who cares about the vision, if ultimately they are doing the tasks as accurately as they were doing them before? That is what's important."
"The quality of the vision may not be quite as sharp" after dilation, Andrew Iwach, MD, tells WebMD. "The issue is, will you see the dog? Will you see the child run out? Those types of large objects you should be able to see." Iwach, an assistant clinical professor of ophthalmology at the University of California, San Francisco, is also a spokesperson for the American Academy of Ophthalmology.
The study's authors conclude that, while deterioration of vision and driving ability does not necessarily occur when dilating drops are used in young and healthy adults, the drops could have an important impact in older people.
"The bottom line is 'safety first,' and common sense usually gets you through things," Iwach says.
"What most people would like to know is, can I drive or can I not drive? And it is not quite that simple to answer that question," he says. "The reason is the effect of dilation will be different ... depending on the [vision] of that individual patient." And an older patient might have glaucoma or cataracts, two common conditions that could compound the effects of the dilation drops.
Other factors, besides a person's eye health, that Iwach says are important include: driving conditions (time of day, amount of traffic, weather, and distance), how the drops affect the individual, what kinds of tests were performed during the exam (which can also lead to temporary problems), and how comfortable a patient is.
"The reality is, there are multiple factors that come into play," says Iwach. "In most cases - certainly in healthy patients -- they are safe [driving], but when in doubt, it is safest to have someone else do the driving.