Visual field impairment associated with vehicle accident rate

Chicago-A recent cohort study indicates that older individuals with glaucoma drive at least as safely as other individuals of that age without the disease. However, a nested case control study of drivers from the first study showed that moderate-to-severe impairment in the central 24° field of their worse eye is associated with an increased risk of being involved in a vehicular crash, said Cynthia Owsley, MSPH, PhD, professor of ophthalmology, University of Alabama at Birmingham.

In the first study, Dr. Owsley and colleagues used accident reports and other means to compare the at-fault crash rate of 516 drivers over age 50 diagnosed with glaucoma and that of 115 drivers who did not have the disease.

“There was no difference in the at-fault crash rates of drivers with and without glaucoma,” she said.

These findings suggest that mandatory reporting of drivers diagnosed with glaucoma to state motor vehicle departments would be an inefficient way of identifying at-risk drivers, Dr. Owsley concluded.

However, results of the nested cohort study, which included calculation of Advanced Glaucoma Intervention Study (AGIS) scores, suggest that certain drivers with glaucoma are at higher risk of involvement in accidents. Drivers with AGIS scores in the worse eye indicating severe corneal visual impairment were six times more likely to be involved in an at-fault crash and four times more likely to incur a crash regardless of fault.

“The AGIS score is a practical, useful marker,” Dr. Owsley said.

The score can signify a point in disease progression at which the physician and patient should begin discussing driver safety. And since the score is easily, routinely computed from automated perimetry tests used in glaucoma management, there is no additional patient or financial burden incurred when practices use it in the interest of public safety, she explained.