Citation

Massof RW, Deremeik JT, Park WL, Grover LL. Invest. Ophthalmol. Vis. Sci. 2007; 48(11): 4955-4962.

Affiliation

Lions Vision Research and Rehabilitation Center, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. rmassof@lions.med.jhu.edu

Copyright

(Copyright © 2007, Association for Research in Vision and Ophthalmology)

DOI

10.1167/iovs.06-0566

PMID

17962445

Abstract

PURPOSE: To validate estimates of self-perceived driving ability from difficulty ratings of driving tasks and to determine the association of the importance and difficulty of driving with the magnitude of visual impairments. METHODS: A consecutive series of 851 patients at a low-vision clinic rated the importance of driving on a four-point scale. Those who gave nonzero importance ratings then rated driving difficulty on a five-point scale. Those who gave nonzero difficulty ratings then rated the difficulty of each of 21 driving tasks on a five-point scale. Visual acuity was measured with the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart, and contrast sensitivity was measured with the Pelli-Robson chart. Rasch analysis was used to test the validity and reliability of self-perceived driving ability estimates from difficulty ratings of tasks. RESULTS: Patients who rated driving as not important (41%) had worse visual acuity (logMAR = 0.88) and worse contrast sensitivity (log CS = 0.83) than did those who rated driving as extremely important (55%; logMAR = 0.62; log CS =1.03; multivariate analysis of variance [MANOVA]; P = 0.003). Self-perceived driving ability correlated negatively with the overall rating of driving difficulty (r = -0.69; P < 0.001) and with logMAR (r = -0.28; P < 0.001), and correlated positively with log CS (r = 0.35; P < 0.001). The most difficult driving tasks were navigating in parking ramps, parking in the correct space, seeing lane markings, and reading signs. The least-difficult driving tasks were seeing traffic and reading the speedometer. Rasch analysis confirmed instrument validity and reliability. CONCLUSIONS: Low-vision patients appeared to devalue the goal of driving when visual impairments were more severe. Valid measures of self-perceived driving ability can be estimated from difficulty ratings of specific driving tasks.

Language: en