Study shows some drivers with glaucoma naturally adapt

November 20, 2015
In a new study, glaucoma patients passed a driver’s test if they moved their head and eyes more often.

Some people with glaucoma naturally develop ways to adapt while driving, a new study in Optometry and Vision Sciencereports.

The primary adaptations drivers make are moving their head and eyes side to side and up and down more often, according to the study.

"These are the adaptation techniques that individuals with low vision are taught as part of low-vision training, but we're seeing that people [with glaucoma] learn to do them without any training because subconsciously they realize this is the best way to see what they need to see," says Murray Fingeret, O.D., a member of the Optometric Glaucoma Society.

As glaucoma develops, a person's peripheral visual field begins to shrink, often causing anxiety about driving. The AOA Ethics Forum is currently examining the ethical issues that arise with driving and vision.

In the U.S., people with advanced glaucoma can often keep their driver's licenses because some states only test for visual acuity, not the extent of the peripheral field. Driver's license requirements vary widely from state to state. It can often be up to individuals to self-screen and curtail their own driving if vision worsens. Requirements in the European Union, where this study was conducted, are stricter than in the U.S.

What the Optometry and Vision Science study shows

This German study consisted of a group of participants with glaucoma and a control group. Participants were tested on a sophisticated driving simulator that included acceleration forces, a 360-degree projection and the real car body.

During a 23-mile route, participants faced nine hazardous situations, including pedestrians suddenly appearing from behind parked cars and oncoming cars passing recklessly. If a person failed one of the nine hazardous situations, he or she failed the entire test.

Half of the glaucoma participants and all control participants passed the test. Glaucoma patients who passed moved their heads more than the control group, while those who failed showed no additional head movements.

Those who passed also had longer saccades—the short, jerking of both eyes from one point to another—than those who failed. They also scanned both side to side and up and down, while those who failed tended to scan mostly horizontally.

"The message is not that glaucoma patients with visual field defects can easily offset that vision loss, but rather that some of them who do drive do find ways to perform fairly well," says Anthony Adams, O.D., Ph.D., editor of Optometry and Vision Science and a member of the Optometric Glaucoma Society. "The authors point to the need for eye care professionals to be aware of compensating strategies of some of their patients so they can educate them to adopt such behaviors."

Educating patients about their deficits may be helpful, but teaching them exactly how to develop these adaptations would be more difficult, says Leo Semes, O.D., a member of the Optometric Glaucoma Society.

But, he adds, applying this type of pilot study to every applicant could be valuable moving forward. "To think there would be a driving simulator for everyone would be a dream." He says it's not unreasonable to think that, as virtual reality continues to evolve, jurisdictions in the U.S. might develop more advanced driving tests in the future.

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