Relationships Among Vision,Visual Attention,and Fitness to Drive in Adults With Multiple Sclerosis

BACKGROUND: Persons with multiple sclerosis (PwMS) may experience visual ability (e.g., poor contrast sensitivity) or visual–cognitive impairments (e.g., slow visual attention) that impact their driver fitness (Schultheis et al., 2010)—that is, their ability to control a motor vehicle, with or without technology, to keep up with the flow of traffic. But the impact of these clinical impairments on fitness to drive is not well studied. Typically, visual acuity is screened for, and licensing agencies do not consider visual–cognitive impairments that may impair driver fitness. Consequently, some may experience impairments that increase their crash risk or lead to license revocation or driving cessation, which compromise their independence.

PURPOSE: To understand the visual–cognitive impact on fitness to drive in PwMS, we asked three questions: Are there significant differences (1) in clinical and on-road outcomes between PwMS versus healthy control drivers (HC)? (2) in those outcomes between PwMS who passed versus failed the on-road assessment? and (3) in the correlations between clinical and driving errors in PwMS?

DESIGN: We used a prospective research design with a convenience sample for PwMS and an existing data set for HC (age 65–75) who underwent the same driving assessment protocol. PwMS were recruited from MS clinics affiliated with the London Health Sciences Centre.

METHOD: Individuals ages 18–59 yr were included if they had a physician-verified diagnosis of MS, cognitive impairment, and low physical disability. Ethics approval was obtained for PwMS and the HC data set. Thirty PwMS completed a visual assessment using the OPTEC^® 2500 (Stereo Optical, Chicago) and visual attention assessment using the useful field of view test before completing a standardized, valid, and reliable on-road assessment (Classen et al., 2016), as assessed by an occupational therapist certified driver rehabilitation specialist and a certified driving instructor. Analyses included summary statistics for all variables; Wilcoxon rank-sum tests for between-group differences on clinical and on-road outcomes and for within-group differences for those with PwMS who passed versus failed the on-road assessment; and Spearman’s rho correlations for quantifying the relationships between clinical and driving errors in PwMS.

RESULTS: PwMS (vs. HC) had intact contrast sensitivity, χ²(1) = 4.05, p = .04, and better selective attention (W = 1761, p < .0001) but made more errors in visual scanning (W = 11903, p < .0001), wide lane turns (W = 9932, p < .0001), vehicle positioning (W = 11449, p < .0001), adjustment to stimuli (W = 11352, p < .0001), and total number of driving errors (W = 12139, p = .03). PwMS who failed (vs. passed) the on-road assessment made more adjustment to stimuli (W = 317.5, p = .01), gap acceptance (W = 333, p = .03), and total number of driving errors (W = 318, p = .015). These errors, classified as critical driving errors, are predictive of motor vehicle crashes (Classen, Shechtman, Awadzi, Joo, & Lanford, 2010), suggesting that PwMS who fail an on-road assessment may make more total and critical driving errors. We observed moderate correlations between visual processing speed and gap acceptance (r = .40, p = .03) and between visual acuity and adjustment to stimuli (r = .47, p = .01), suggesting that visual acuity and visual processing speed associated with critical driving errors may identify at-risk drivers.

CONCLUSION: We concluded that visual–cognitive impairments may identify at-risk drivers with MS. Therefore, this study lays the foundation for predicting the role of visual and visual attention in fitness to drive in the MS population and encourages occupational therapists to comprehensively assess the visual and visual attention skills of PwMS before making fitness-to-drive decisions.

References

Classen, S., Krasniuk, S., Knott, M., Alvarez, L., Monahan, M., Morrow, S. A., & Danter, T. (2016). Interrater reliability of Western University’s on-road assessment. Canadian Journal of Occupational Therapy, 83, 371–325. https://doi.org/10.1177/0008417416663228

Classen, S., Shechtman, O., Awadzi, K. D., Joo, Y., & Lanford, D. N. (2010). Traffic violations versus driving errors of older adults: Informing clinical practice. American Journal of Occupational Therapy, 64, 233–241. https://doi.org/10.5014/ajot.64.2.233

Schultheis, M. T., Manning, K., Weisser, V., Blasco, A., Ang, J., & Wilkinson, M. E. (2010). Vision and driving in multiple sclerosis. Archives of Physical Medicine and Rehabilitation, 91, 315–317. https://doi.org/10.1016/j.apmr.2009.09.021