Glaucoma Patients Who Increase Visual Scanning Can Pass Driving Tests
Some people with glaucoma-related binocular (both eyes) vision loss can pass a standard driving test by adopting increased visual scanning behavior, reports a study in the October 2015 issue of Optometry and Vision Science, official journal of the American Academy of Optometry. The journal is published by Wolters Kluwer.
A release from the publisher reports that increased scanning — particularly more frequent head and eye movements — was a key strategy to compensate for visual impairment due to glaucoma. The research was done by Enkelejda Kasneci, PhD, of University of Tübingen, Germany, and colleagues. The release quotes Anthony Adams, OD, PhD, Editor-in-Chief ofOptometry and Vision Science, as saying, “Like most people, many glaucoma patients with binocular peripheral visual field loss can make useful adaptations for their condition,”
Drivers with Glaucoma Adapt by Moving Their Eyes and Head
In a state-of-the-art virtual reality driving simulator at a Mercedes-Benz technology center, six patients with glaucoma and binocular vision loss performed a simulated driving test. With real acceleration, 360-degree visual projection, and a real car body, the moving-base simulator provided a “close-to-realistic driving experience.”
During the 40-minute test, drivers encountered various traffic situations and nine different hazardous situations–for example, pedestrians suddenly appearing behind parked cars or risky passing maneuvers by oncoming cars. Subjects who failed any of the nine hazardous situations failed the driving test.
Eight subjects with normal vision were studied for comparison. In both groups, sophisticated measures of the subjects’ eye- and head-tracking movements were obtained and compared with performance on the driving simulation.
Three of the six glaucoma patients passed the driving test, with performance indistinguishable from that in subjects with normal vision. Compared to patients who failed, passing drivers showed “increased visual exploration”–they made more head movements and more eye movements.
The successful drivers changed fixation (where they looked) more often, and had shorter fixation times than those who failed the driving test. “Such behavior indicates an increased scanning activity in glaucoma patients who passed,” Dr. Kasneci and coauthors write.
In contrast, glaucoma patients who failed the driving test had reduced head and eye movements, with a tendency to a more straight-ahead eye position. Patients who passed the driving test also drove more slowly–perhaps giving them more time to visually scan their environment.