Should visually impaired people drive slow motorised vehicles?: Evaluation of driving safety in mobility scooters

Background: Mobility scooters may help people with motor impairments maintain independent mobility. However, many users have comorbid disorders that can influence their ability to drive safely. Over the past few years, the media have drawn much attention to mobility scooter safety. Visual disorders are a common comorbidity in the elderly population. Whereas much research has been done on the influence of visual impairment on driving safety in fast traffic, hardly anything is known in the domain of slow motorised traffic. The present study therefore investigates the impact of visual impairment on indoor and outdoor mobility scooter safety. Methods: 86 participants (aged 50-75 years, 38 well-sighted controls, 24 people with low visual acuity [Binocular Best Corrected Visual Acuity (BBCVA) between 0.03 and 0.40], 11 people with peripheral visual field defects and 14 people with both low visual acuity and peripheral field defects) completed an unstructured test drive of about half an hour in and around Groningen University Medical Centre. The drives were recorded by a GPS-camera and included different tasks, such as avoiding objects or other traffic participants, crossing a street, and driving with different speeds. Videos were evaluated independently by two orientation and mobility specialists with experience in visual rehabilitation. Results: Driving performance, choice of speed, distance to objects, lateral position, viewing behaviour, and compensation were assessed. As a group, participants with visual impairments could not be classified as a safety hazard when using slow motorised vehicles. Driving safety of participants with low visual acuity was only slightly different from healthy controls. Participants with peripheral field defects encountered more difficulties compared to the other groups. Discussion/conclusion: In general people with visual impairments are capable of driving safely in mobility scooters. Besides visual impairment, factors such as vehicle control and compensation should be considered during evaluation. Therefore, individual assessment is advisable