State driver-licensing agencies in the United States have already enacted, or are now considering, laws requiring mandatory reporting by health care providers of licensed drivers with certain medical conditions. Motor vehicle collisions (MVCs) are among the most potentially adverse mobility-related outcomes that have been reportedly associated with glaucoma.
11 12 13 14 15 16 Hu et al.
11 analyzed MVC records in Iowa from 1985 to 1993 and found that older men with self-reported glaucoma were at an increased risk for an MVC. Another study found that glaucoma, as listed in medical records, was independently associated with injurious MVCs,
13 although there was only a small number of drivers with glaucoma in the sample. Johnson and Keltner
12 reported that persons with bilateral visual field defects (regardless of cause) had a higher frequency of MVCs. Wood and Troutbeck
17 18 and Wood et al.
19 found that simulated binocular visual field restriction limited to a 40° radius field or smaller compromised some aspects of driving performance, such as obstacle avoidance. Persons with glaucoma report more difficulty driving than do control subjects without glaucoma, as measured in health-related quality of life surveys.
7 8 However, not all studies addressing the relationship between glaucoma and driving have reported an association. McCloskey et al.
14 found no evidence that glaucoma increases the risk of injurious collision. The inconsistencies in the literature may be in part due to a person’s ability to compensate for field loss by modifying driving behavior,
20 21 to the use of self-report diagnosis as the case definition,
11 or to failure to account for driving exposure.
12 In fact studies have documented that many persons with visual impairment self-regulate their driving by reducing their exposure to driving situations they find more difficult (rain, night, heavy traffic, and rush hour) and are less likely to engage in risk-taking driving behavior,
22 thus potentially reducing their risk of MVCs.
20 23