New Study Suggests Glaucoma Patients May Be at Higher Risk of Car Accidents

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PHILADELPHIA—A new study from Wills Eye Hospital in Philadelphia found that the rate of those accidents among patients with moderate glaucoma and with mild vision loss was almost five times higher than expected for Pennsylvania drivers in this age group. The study followed a group of 161 patients with an average age of 64 with moderate open angle glaucoma in at least one eye over four years. Each year, patients were asked if they were a driver in any motor vehicle accidents during the previous year.

The study evaluated different aspects of vision, such as visual acuity, peripheral vision and contrast sensitivity—whether you can tell not just black or white but can you differentiate between dark gray from light gray. It also considered patients’ ability to do certain normal daily activities like reading street signs and finding objects on a crowded shelf.

“What we found was between 5 percent and 10 percent of these glaucoma patients were involved in motor vehicle accidents each year despite still having vision good enough to legally qualify for driving,” said, Jonathan S. Myers, MD, chief of the Wills Eye Hospital Glaucoma Service who was involved in the study and a presenter at the research conference. This compares to a 1.1 percent rate of motor vehicle accidents for drivers of similar age to these (61 to 65 years old) reported by 2017 Pennsylvania Crash Facts. In the study, the National Eye Institute Visual Function Questionnaire was used measuring vision-related quality of life and the Glaucoma Symptom Scale measuring eye comfort at each of the visits.

“One finding that stood out was that interestingly, it was the peripheral vision in the worst eye that made the biggest difference. That suggests that in some study patients, significant blind spots existed which could have been a liability for driving,” said Myers. For most states, the legal vision requirements for driving, are 20/40 vision for night and 20/70 for daytime driving, although daytime driving requirements vary. Some states also require between 120 and 140 degrees of side to side vision for driving.

“It’s a very common predicament especially as we have an increasingly aging population, vision disturbances are more common as we grow older,” added Myers. The most common causes of reduced vision are cataracts—which can be fixed, followed by macular degeneration in a Caucasian population and glaucoma in the African American and Hispanic populations. Glaucoma is not reversible; the sight in macular degeneration can be improved in some cases.

“It’s increasingly common to address driving with families. Driving isn’t simply about driving, it’s also about independence for an aging population, so these can be very difficult and emotional conversations. As doctors, we need to care for the whole patient and be part of the care team with the family,” noted Myers.