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Driving simulation shows importance of specific hemifield in collisions
Impaired sensitivity in the inferior visual field was correlated with a higher risk of motor vehicle collisions in a study using driving simulators.
The study included 43 normal subjects and 95 patients with advanced glaucoma. The simulation focused on two scenarios in which an oncoming car turned into the driver’s path at an intersection.
The proportion of subjects who were involved in one or more collisions was significantly higher among patients with advanced glaucoma (80%) than among normal subjects (26%).
In the glaucoma group, the subjects involved in collisions were older, had worse visual acuity and significantly lower sensitivity in the inferior integrated visual field (IVF) hemifield.
These results suggest that damage to the inferior IVF hemifield, which remains relatively preserved until the later stages of the disease, might expose glaucoma patients to increased risk of road accidents, at least in the specific situation proposed by the simulator.
As the authors pointed out, glaucoma causes various types of visual field defects that do not affect central visual acuity and may, therefore, not be sufficiently considered during the tests performed to retain a driver’s license. Although each road accident has different circumstances, “the degree of the risk may depend on the specific area of the visual field that is affected,” the authors noted.
“This study confirms the importance of the inferior IVF hemifield in patients with advanced glaucoma who continue driving,” they concluded. – by Michela Cimberle
Disclosure: Kunimatsu-Sanuki has no relevant financial disclosures. Please see the study for the other authors’ financial disclosures.
Perspective
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When it comes to patient care, driving is always a difficult subject to broach. As we get older, losing our ability to drive not only signifies the loss of our independence, but it is also a sign that we are physically declining, in some sort of capacity.
As demonstrated by Kunimatsu-Sanuki and colleagues, damage to the inferior hemifield may expose glaucoma patients to a higher risk of motor vehicle collision, as the field loss would seemingly alter the ability to see the road, passing cars, etc.
When assessing a patient’s ability to drive, it is critical to take into consideration more than just visual acuity and peripheral vision, as an individual’s cognition, response time and memory are similarly important.