Functional assessment involves assessment of a patient's visual, physical, and cognitive abilities. Adequate function in these areas is needed to drive safely. Most of a functional assessment can be done by primary health care practitioners, but specialists (eg, ophthalmologists, neuropsychologists, subspecialists, occupational and physical therapists, driving rehabilitation specialists) may need to be consulted. Identified deficits may require interventions (see Interventions with the Older Driver), including driving rehabilitation, assistive devices, reporting to the state Department of Motor Vehicles, driving restrictions or cessation, or a combination. Some complicated cases may be referred to state medical advisory boards. One useful resource is the American Geriatrics Society's Physician's Guide to Assessing and Counseling Older Drivers.
Visual function is vital to safe driving. Age-related and pathologic changes in vision are common and can contribute to driving impairment.
Changes with aging include
Ocular diseases common with aging include
In many states, central visual acuity and peripheral vision are routinely tested by the Department of Motor Vehicles when a license is renewed. Most states require 20/40 visual acuity in at least one eye for unrestricted licensing (glasses or contacts are allowed). However, in some states, practitioners can extend the requirement pending medical justification. Additionally, some states have approved use of bioptics (a lens system with a telescope attached to a pair of glasses) for people with severely reduced vision. For horizontal peripheral vision, safe driving thresholds vary widely among states from no requirement to about 140°.
Tests of useful field of view (spatial area from which visual stimuli can be acquired during a single fixed glance) provide integrated measures of visual performance (eg, visual-processing speeds, visual-spatial attention, visual memory) and can be used to predict a higher risk of MVC. For example, the incidence of MVCs is 6 times higher when useful field of view is reduced by > 40%. However, field-of-view tests are not yet widely available for the in-office practitioner.
Older drivers often require referral to an ophthalmologist for comprehensive testing.
Various parameters of physical function can be assessed in the office.
Physical and occupational therapists who specialize in driving rehabilitation can provide comprehensive testing of motor function related to driving ability. A rehabilitation driving assessment sometimes also involves the specialist going out in a vehicle with the patient to evaluate actual driving skills. The vehicle used during the evaluation should be equipped with features that allow the specialist to maintain safe control (eg, passenger-side brake). Driving rehabilitation specialists can be located by contacting local rehabilitation facilities or going to www.driver-ed.org. However, in most states, the cost of a rehabilitation driving assessment is not covered by insurance (Medicare or private) and may be an out-of-pocket cost.
The incidence of cognitive impairment increases in people ≥ 65. People with cognitive impairment often do not recognize their limitations and are at higher risk of MVCs; risk increases with severity of impairment. Although no one test has been found to completely and accurately predict driving safety, some tests are able to provide some level of predictability regarding impaired driving performance in older adults. These tests include the following:
Drivers with mild cognitive impairment should be considered for referral for more precise neuropsychologic assessment.
Last full review/revision September 2013 by David B. Carr, MD; Peggy P. Barco, MS, BSW, OT/L
Content last modified September 2013