EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/387844
EW GLAUCOMA 92 October 2014 Practical applications Ophthalmologist currently have few options to choose from when facing a patient whose driving ability is in question. As the studies above have illustrated, there are visual function tests that are associated with driving ability, but there are no absolute cut- off values to inform decision-making in individual patients. "Driving with low visual acuity is a significant security and public health problem," Dr. Morfeq said. One approach that is often acceptable to patients and their families alike is to suggest a driving test at a local driving school. This recommendation demonstrates the physician's engagement in this difficult life decision, while simult - neously transferring the challenging decision about driver worthiness to experts better trained to conduct such evaluations. EW Editors' note: The sources have no financial interests related to their comments. Contact information Morfeq: dr.morfeq@gmail.com Glen: fiona.glen.2@cit .ac.uk Wood: j.wood@qut.edu.au Eye disease and driving by Tony Realini, MD, MPH in the presence of inferior defects," she said. Driving with glaucoma Glaucoma is among the most com- mon causes of visual field defects. Joanne Wood, PhD, and colleagues at Queensland University of Technology, Brisbane, Australia, evaluated the on-road driving performance of older adults with glaucoma versus healthy controls. Subjects drove an 11.5-mile route in a dual-brake car accompa- nied by a driver-trained occupation- al therapist masked to glaucoma status. Performance was assessed on nearly 150 driving maneuvers in multiple different driving settings. "Glaucoma participants made more errors at traffic lights, at right-of-way intersections, and in bidirectional driving, and had more errors involving lane position and gap selection, such as accurately judging distances and speeds when entering traffic or changing lanes," she said. Of a battery of visual function tests that included acuity, visu- al fields, contrast sensitivit , and motion sensitivity, she said that the latter was "the best visual predictor of the overall driver safety rating." that is most likely to affect driving performance," said Fiona Glen, PhD, a post-doctoral researcher at City University, London. To further explore this issue, she and colleagues conducted a creative experiment funded by the International Glaucoma Association. In the U.K., all new drivers are assessed by a Hazard Perception Test (HPT), a computer-based assessment that requires people to respond to hazards in a series of real-life driving videos. Dr. Glen's group paired the HPT with a gaze-tracking system that creates focal distortions to simulate regions of visual field degradation, allowing people with otherwise normal vision to experi- ence the effects of visual field loss. These simulated field defects move with the study participant's gaze as the driving test is carried out. Thirty subjects took the test 3 times: once with no simulated field defects, once with simulated superior field defects, and once with simulated inferior field defects. The 3 trials were co - ducted in random order to minimize any learning effects or fatigue issues. "Compared to the trial with no simulated defects, the mean group score decreased by 18% in the pres- ence of superior defects and by 12% When should patients no longer drive due to vision loss? N o one likes to be the bad guy. So when your patient asks, "Doctor, is it still safe for me to drive?" (or more frequently, when the adult child accompanying your patient asks, "Should Mom still be driving?"), you find yourself in an awkward position, for 2 reasons. First, you don't want to be the one to curtail someone's driving and potentially deprive her of indepen- dence; and second, many of us are unqualified to honestly and acc - rately assess the driving ability of our patients with moderate vision loss. It is easy when the better- seeing eye has visual acuity worse than 20/200 or the visual field is constricted to within the central 20 degrees, rendering the patient legal- ly blind. This definition is codifie in federal law and is unambiguous. But what about the patient with moderate glaucoma, arcuate defects in both eyes, and visual acuity of 20/40? Depending on the state, this may qualify the patient for a driver's license. But that is a differ- ent issue than what the patient or child asked: not can Mom drive, but should she? Visual impairment and driving Patients with impaired vision are out there on the roads. Hussein Morfeq, MD, University of Picardie Jules Verne, Amiens, France, and colleagues conducted a cross- sectional study of 533 licensed European drivers 18 years or older. Of these, nearly 20% had binocular visual acuity worse than 20/40 (the legal limit for licensure in Europe). Of those with impaired vision, 62% reported driving on a daily ba- sis, 27% drove at least once a week, and 11% reported driving only occasionally. In the 11 months that these patients' driving patterns were assessed, the group with visual im- pairment drove an average of nearly 4,000 miles each. Defect type and collision risk "Little is known about the loca- tion and type of visual field defect