Vision Impairment and the Older Driver
By Kent Higgins, PhD
Older drivers represent one of the fastest growing segments of the driving population. By the year 2020, an estimated 50 million people over the age of 65 will be eligible to drive. As it is also well known that visual abilities decline with age -- both normally and with age-related eye disease -- it is tempting to speculate that vision loss might be responsible for increased accident rates among older drivers. If this were the case, it might be possible to decrease accident risks among older adults with a visual screening program that denies licensure to older drivers with vision loss sufficient to make them "unsafe."
Determining Research Criteria
For researchers,
the major challenge is to design studies that enable the development of
an empirically justifiable set of vision standards for driver
licensure. Variations in requirements state to state indicate that
research has thus far failed to provide such adequate standards. Thus,
while it is simple in principle to formulate stricter vision testing
(and retesting) procedures to deal with the increasing prevalence of
vision loss in an aging driving population, these new standards may be
as difficult to defend as the current ones.
Numerous studies have attempted to relate visual abilities (static visual acuity, dynamic visual acuity, visual fields, etc.) to accident records in the general driving population. While many have reported statistically significant relationships, the magnitudes of the relationships were, at best, weak.
Even those studies that focused on older drivers with a history of at-fault accidents and documented vision loss found only weak relationships between traditional vision test results and accident risk (Ball et al. 1993). And more recent reviews (Charman, 1997; Owsley & McGwin, 1999) suggest that empirical evidence has not changed appreciably since that 1993 statement. Thus, it is not clear that implementing stricter acuity and visual field standards, and a more frequent schedule of vision retests, would produce a measurable reduction in accident risks for older drivers.
Progressing in New Directions
There is reason to
be optimistic. A number of excellent ongoing research programs promise
to advance significantly our understanding of the complex behavior of
driving a car by older drivers and drivers who are visually impaired.
In addition, The National Eye Institute recently funded a bioengineering research partnership grant to develop new optical and electronic devices designed to restore the interplay of central (high-resolution) and peripheral (wide-field) vision for persons with different types and amounts of vision loss. This research effort will also evaluate the efficacy of the proposed devices through laboratory (virtual) and field (real world) tests of pedestrian and driving mobility. This project, for which Lighthouse International is one of many partners, is being led by Dr. Eli Peli of the Schepens Eye Institute in Boston. Through combined simulator and on-road testing, this research should provide valuable information relating to the minimal visual requirements for the safe operation of a motor vehicle and the extent to which low vision devices provide compensation for vision loss while driving.
The full reference for the Peli book is: Peli, E., and Peli, D. 2002. Driving with Confidence: A Practical Guide to Driving with Low Vision. New Jersey: World Scientific.
Kent Higgins, PhD, Vice President for Vision Research
Arlene R. Gordon Research Institute, Lighthouse International.
References:
Ball, K., Owsley, C., Sloane,
M.E., Roenker, D.L., and Bruni, J.R. (1993). Visual attention problems
as a predictor of vehicle crashes in older drivers. Investigative Ophthalmology and Visual Science, 23, 3110-3123.
Charman, W.N. (1997) Vision and driving. Ophthalmic and Visual Optics, 17, 371-91.
Owsley, C. & McGwin, G. (1999). Vision impairment and driving. Survey of Ophthalmology, 43, 535-550.
Peli, E., and Peli, D. 2002. Driving with Confidence: A Practical Guide to Driving with Low Vision. New Jersey: World Scientific.
Source: Lighthouse International's Aging & Vision newsletter (Summer-Fall 2001)
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