Journals of Gerontology: MEDICAL SCIENCES
Cite journal as: J Gerontol A Biol Sci Med Sci. 2013 May;68(5):567–573
doi:10.1093/gerona/gls185
© The Author 2012. Published by Oxford University Press on behalf of The Gerontological Society of America.
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Advance Access publication September 14, 2012
A Population-Based Examination of the Visual and
Ophthalmological Characteristics of Licensed Drivers
Aged 70 and Older
Cynthia Owsley,1 Gerald McGwin Jr.,1,2,3 and Karen Searcey1
Department of Ophthalmology, School of Medicine, Department of Epidemiology, School of Public Health, and
3
Department of Surgery, Section on Trauma, Burns, and Surgical Critical Care, School of Medicine, University of Alabama
at Birmingham.
1
2
Address correspondence to Cynthia Owsley, PhD, Department of Ophthalmology, University of Alabama at Birmingham, 700 S. 18th Street, Suite
609, Birmingham, AL 35294-0009. E-mail: [email protected]
Background. Safe driving performance depends on visual skills yet little is known about the prevalence of vision
impairments in older drivers and the eye conditions that cause them. This study is a population-based examination of the
prevalence of vision impairment and major ophthalmological conditions among drivers aged 70 and older.
Methods. The source population was a random sample of 2,000 licensed drivers aged 70 and older residing in north
central Alabama. All had driven within the past 3 months. Binocular visual acuity and contrast sensitivity were assessed.
The Useful Field of View subtest 2 and Trails B assessed visual processing speed. Ophthalmological diagnoses for cataract, intraocular lens placement, glaucoma, diabetic retinopathy, age-related macular degeneration, and diabetic retinopathy were obtained through medical records from the most recent eye examination.
Results. Ninety-two percent of drivers had visual acuity of 20/40 or better; only two drivers (0.1%) had acuity worse
than 20/100. Ninety-three percent had normal contrast sensitivity (≥1.5). About 40% had slowed visual processing speed
(44%, Useful Field of View; 38%, Trails B). The most common eye condition was cataract, with more than half having
cataract in one or both eyes (56%); yet by the 80s and 90s, the prevalence was low, with most drivers having undergone
cataract surgery and intraocular lens placement.
Conclusions. This population-based study suggests that serious impairment in central vision—visual acuity or contrast sensitivity—is rather uncommon in older drivers; however, slowed visual processing speed is common.
Key Words: Aging—Driving—Vision impairment—Eye disease
Received February 19, 2012; Accepted July 27, 2012
Decision Editor: Stephen Kritchevsky, PhD
S
everal chronic eye diseases of adulthood are common among the older adult population in the United
States. Recent estimates based on epidemiological studies
indicate that about 10 million older adults in the United
States have age-related macular degeneration that can
cause deficits in acuity and contrast sensitivity in central
vision (1). Approximately 2.5 million adults aged 40 and
olderhave glaucoma that leads to peripheral vision loss and
in more severe forms, central vision loss (2), and about
4 million have diabetic retinopathy that impairs many
aspects of vision (3). The increased optical density (ie,
opacity) of the crystalline lens is inevitable in all aging
eyes (4). Functionally significant cataract is common
with an estimated 20.5 million adults in the United States
having cataract in one or both eyes (5). The numbers of
older Americans who have these conditions is expected to
increase over the next 10 years given the aging of the baby
boom generation.
Driving is inarguably a visual task, and certain types
of visual sensory and higher order visual processing
impairments in older drivers have been linked to impaired
driving performance and increased motor vehicle collision
(MVC) risk (6). The high prevalence of vision-impairing eye
conditions among older adults, and other aging-associated
functional problems, has caused societal concern about the
safety of older drivers (7–9). Yet, there is little known on a
population basis about how pervasive visual impairments
are in older drivers, as well as the eye conditions that cause
them. Some older adults voluntarily stop driving because
of visual problems, either on their own or at the urging of
their families, friends, physicians, and/or other health care
providers (10–12). Others do not get their licenses renewed
567
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OWSLEY ET AL.
because they do not meet their state’s vision standards
for licensing. Thus, relying on population-based studies
about the prevalence of eye disease and vision impairment
in the overall older adult population is inadequate for
estimating eye disease and vision impairment rates for
the driver segment of this population, and could lead to an
exaggeration of the percentage of older drivers with eye
disorders and vision impairment who are actually behind
the wheel.
The purpose of this study is to conduct a population-based
examination of licensed drivers aged 70 and older to determine the prevalence of vision impairment and the common
ophthalmological conditions of later adulthood (age-related
macular degeneration, glaucoma, diabetic retinopathy, and
cataract). In characterizing vision, the researchers have
examined both visual sensory function as well as higher
order visual processing characteristics.
Methods
This study was approved by the Institutional Review
Board of the University of Alabama at Birmingham. The
source population consisted of adults aged greater than or
equal to 70 years who resided in Jefferson County, Alabama
or the border areas of contiguous counties. Potential participants were randomly identified from contact information available through a list of persons obtained from a
direct marketing company (Pinpoint Technologies, Tustin,
CA). The researchers then confirmed driver’s license status through the Alabama Department of Public Safety, and
eliminated those from the target population who did not
hold Alabama licenses. Potential participants were randomly selected from the final list, received a letter, and telephoned to confirm eligibility. Persons who stated they had
an Alabama license and had driven within the last 3 months,
were aged 70 and older, and spoke English were invited for
a study visit. Participants were enrolled between October
2008 and August 2011. The target sample for enrollment
was 2,000 drivers.
Following written informed consent, the study visit
had two parts. The first part consisted of questionnaires.
A trained interviewer administered a demographic review
(age, gender, race/ethnicity, education, and marital status),
a general health questionnaire about the presence versus
absence of chronic medical conditions (ie, “has a doctor ever told you that you have...”) (13), questions about
smoking (14) and alcohol use (15), the Mini-Mental State
Examination (MMSE) (16), and asked how many days the
person drove in a typical week in recent months (17).
The second part of the visit consisted of visual screening
tests. Both visual sensory tests for central vision and visual
processing speed tests were included. The specific tests
described later were selected because of their established
relevance to driving performance, licensure, or driver safety
in older drivers (6,18–21). For all testing, measurements
were made under “habitual correction” if they had one, that
is, participants wore whatever spectacles or contact lenses
they would normally wear for that viewing distance. All
tests were administered under binocular viewing unless
noted. (a) Visual acuity for letters was assessed using the
Electronic Visual Acuity system (22), and expressed as log
minimum angle resolvable. (b) Contrast sensitivity was
assessed using the Pelli–Robson Contrast Sensitivity Chart
(23), and was scored by the letter-by-letter method (24). (c)
Visual processing speed under divided attention conditions
was examined by the UFOV subtest 2 (Visual Awareness
Research Group, Punta Gorda, FL) (20). This screening test,
administered on a computer, estimates the amount of time
in milliseconds that a person needs to discriminate which
of two test targets is presented at fixation in central vision,
while simultaneously identifying the location of a peripheral
target in the 10° radius field. (d) Visual processing speed
while dividing attention was also assessed using the Trails
B test (25), a paper and pencil test that also relies on executive control abilities. These visual processing speed tests
can also considered as cognitive tests because they involve
higher order information processing components.
The presence of common chronic age-related eye conditions was determined by obtaining a copy of participants’
most recent eye examination performed by an ophthalmologist or optometrist. Participants completed a signed
medical record release authorizing the study to obtain
these records. An experienced coder of eye medical records
recorded whether the participant had diagnoses of cataract,
age-related macular degeneration, diabetic retinopathy or
diabetic macular edema, glaucoma, or had an intraocular
lens (IOL) (meaning that cataract surgery had been performed). The diagnoses were coded separately for each eye.
The coder was masked to all other data collected on the
participant, and agreement with a second coder was high
(91.4%).
Chi-square and t tests were used to compare demographic,
health, vision, and driving characteristics across age groups
(ie, those in their 70s, 80s, and 90s). p values of ≤.05
(two-sided) were considered statistically significant.
Results
A total of 18,544 persons were contacted by a letter
describing the study. Of those who were sent letters, 61%
(11,267 of 18,544) were successfully reached by telephone.
Of those reached by telephone, 30% (3,412 of 11,267)
agreed to answer questions from the eligibility screener. Of
those who completed the telephone screener, 70% (2,389 of
3,412) were eligible. Eighty-four percent (2,000 of 2,389)
of persons meeting eligibility criteria consented to participate. The eligible persons who participated were on average 1 year younger (77 years old) than those who declined
participation (78 years old) (p < .0001) and were also more
likely to be male participants (p < .0001).
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Table 1. Demographic Characteristics and Days of Driving Per Week of the Sample of Older Drivers Aged ≥70 y
Age
Characteristic
n, %
Gender
Men
Women
Race
African American
White
Other
Marital status
Married
Single
Separated
Divorced
Widowed
Education
Less than high school graduate
High school graduate or general
equivalency diploma
1–4 y of college
Postgraduate degree
Days driven per week
1–2
3–4
5–6
7
Mean (SD)
70–79 y old
80–89 y old
90–99 y old
p Value
All Ages
n = 1,433
n = 527
n = 40
814 (56.8)
619 (43.2)
293 (55.6)
234 (44.4)
23 (57.5)
17 (42.5)
258 (18.0))
1,166 (81.4)
9 (0.6)
90 (17.1)
437 (82.9)
0 (0)
3 (7.5)
37 (92.5)
0 (0)
847 (59.1)
89 (6.2)
2 (0.1)
132 (9.2)
363 (25.2)
233 (44.2)
44 (8.4)
1 (0.2)
19 (3.6)
230 (43.6)
12 (30)
1 (2.5)
0 (0)
1 (2.5)
26 (65.0)
82 (5.8)
414 (28.9)
48 (9.1)
128 (24.3)
3 (7.5)
8 (20.0)
133 (6.7)
550 (27.5)
714 (49.9)
222 (15.5)
277 (52.6)
74 (14.0)
27 (67.5)
2 (5.0)
1,018 (50.9)
298 (14.9)
90 (6.2)
270 (18.8)
330 (23.0)
743 (51.6)
5.7 (1.7)
40 (7.6)
115 (21.8)
117 (22.2)
255 (48.4)
5.5 (1.8)
5 (12.5)
12 (30)
9 (22.5)
14 (35.0)
4.9 (2.0)
.8848
1,130 (56.5)
870 (43.5)
.5626
351 (17.5)
1,640 (82.0)
9 (0.5)
<.0001
1,092 (54.6)
134 (6.7)
3 ( (0.1)
152 (7.6)
619 (31.0)
.0014
.1327
Participants ranged in age from 70 to 98 years old. As
shown in Table 1, 72% of the sample was in the 70s, 26%
in the 80s, and 2% in the 90s. In each decade, men were
slightly more common than women (~56% vs ~44%).
Eighty-two percent of the sample was white, 17.5% African
American, and 0.5% of other races/ethnicities. This breakdown manifested within each decade of age, although there
was a nonsignificant disproportionate number of whites in
the 90s as compared with African Americans. Drivers in
their 70s and 80s were split about evenly between those who
were married versus not (either single, separated, divorced,
or widowed), whereas most drivers in their 90s (70%) were
not married. The vast majority of drivers (93.3%) had completed the equivalent of a high school education or beyond.
Approximately 70%–75% of drivers in their 70s and 80s
reporting driving at least 5 days per week; for those in
their 90s, just more than half (57%) drove at least 5 days
per week.
Approximately 50% of the sample had three or fewer
medical comorbidites (Table 2). This was the case for those
in their 70s and in their 90s, but those in their 80s had a
lower rate of less than or equal to 3 comorbidities at 40%.
In general the medical comorbidity distribution for those
in the 90s was shifted toward fewer comorbidities as compared with those in younger decades of age.
Medical records from the most recent eye examination
were obtained for 95% (1,899 of 2,000) of participants;
135 (6.8)
397 (19.9)
456 (22.8)
1,012 (50.6)
5.6 (1.7)
71% of these examinations were within 1 year of the enrollment date, and 87% were within 2 years. Reasons for
not obtaining medical records on the remaining 5% (101
of 2,000) were the participant declined to sign the medical release (2), participant could not identify an eye care
provider they had seen (59), participant signed the release
but the eye care provider had no record on file for that person (38), or the eye care provider never sent us the record
despite the researchers sending the medical release and
repeated requests (2). Half of all drivers in the sample had
cataract in one or both eyes, and half had IOLs in one or
both eyes. There were noteworthy differences by decade
however. Sixty-four percent of drivers in the 70s had cataract, with this percentage decreasing to 39% in the 80s and
26% in the 80s. Correspondingly, the percentage of those
with an IOL in one or both eyes (meaning they had undergone cataract surgery) trended in the opposite direction by
age, being lowest in the 70s to 39%, increasing in the 80s to
66%, and in the 90s to 85% of drivers.
With respect to glaucoma and related conditions, 18%
of the sample had been diagnosed with glaucoma, being
glaucoma suspects, or having ocular hypertension. The
percentage of drivers with glaucoma-related conditions
increased with age from 17% in their 70s to 36% in their
90s having these conditions. The prevalence of age-related
macular degeneration also increases with each decade of
age rising from 16% in the 70s to 26% in the 90s. Diabetic
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OWSLEY ET AL.
Table 2. Health Characteristics of the Sample of Older Drivers Aged ≥70 y Including Number of Medical Comorbidities, Eye Conditions,
Smoking and Alcohol Use, and Mental Status
Age
Characteristic
n, %
No. of medical comorbidities
0–1
2–3
4–5
6–7
8–9
≥10
Eye conditions*
Cataract
Glaucoma
Diabetic retinopathy or diabetic macular edema
Age-related macular degeneration
Intraocular lens
Smoking
Never
Previous
Current
Alcohol use, drinks per week
None
1–7
8–14
≥15
Mean (SD)
Mental status
24–30
17–23
<17
Mean (SD)
70–79 y old
80–89 y old
90–99 y old
p Value
All Ages
181 (12.6)
530 (37.0)
494 (34.5)
177 (12.4)
45 (3.1)
6 (0.4)
41 (7.8)
175 (33.2)
187 (35.5)
94 (17.8)
26 (4.9)
4 (0.8)
4 (10)
16 (40)
13 (32.5)
6 (15.0)
1 (2.5)
0 (0.0)
867 (63.8)
234 (17.2)
56 (4.1)
219 (16.1)
523 (38.5)
196 (39.0)
99 (19.7)
8 (1.6)
114 (22.7)
333 (66.3)
10 (25.6)
14 (35.9)
0 (0)
10 (25.6)
33 (84.6)
<.0001
.0074
.0136
.0022
<.0001
1,073 (56.5)
347 (18.3)
64 (3.4)
343 (18.1)
889 (46.8)
668 (46.7)
682 (47.7)
80 (5.6)
252 (47.9)
261 (49.6)
13 (2.5)
24 (61.5)
15 (38.5)
0 (0)
.0125
944 (47.3)
958 (48.0)
93 (4.7)
675 (47.1)
616 (43.0)
83 (5.8)
59 (4.1)
2.1 (4.8)
253 (48.0)
224 (42.5)
34 (6.5)
16 (3.0)
2.0 (4.5)
19 (47.5)
16 (40.0)
3 (7.5)
2 (5.0)
1.9 (4.0)
.9282
947 (47.4)
856 (42.8)
120 (6)
77 (3.9)
2.1 (4.7)
1413 (98.6)
19 (1.4)
1 (0.1)
28.4 (1.7)
502 (95.3)
24 (4.6)
1 (0.2)
27.7 (2.3)
38 (95.0)
2 (5.0)
0 (0)
27.1 (1.7)
.0106
226 (11.3)
721 (36.1)
694 (34.7)
277 (13.9)
72 (3.6)
10 (0.5)
.0004
1,953 (97.6)
45 (2.3)
2 (0.1)
28.2 (1.9)
Note: SD = standard deviation.
*In at least one eye.
retinopathy and diabetic macular edema were less common
than the other chronic eye conditions of aging and also had
opposite trends, being more common among drivers in their
70s (4%) than in their 80s (2%), and not present in any of
the participants in their 90s.
A low proportion of drivers in the sample were current
smokers (5%), with none in the 90s being smokers. The
extent of alcohol use was similar across all three decades.
About 47% reported not using alcohol at all and 43% reported
having between 1–7 drinks per week. Approximately 4%
said that they had 15 or more drinks per week. The vast
majority of the sample (98%) had MMSE scores greater
than or equal to 24; of those who had scores greater than or
equal to 24, 73.3% had scores from 28 to 30. The percentage
of those with scores less than 24 was higher in the 80s (5%)
and 90s (5%) compared with the 70s (0.1%).
Just over half the sample (56.7%) had visual acuity of
20/20 or better (Table 3). More than 90% of the sample had
visual acuity of 20/40 or better. The distribution of visual
acuity was displaced to worse values with advancing decade of age, however, even in the 90-year-olds, 70.7% had
acuity of 20/40 or better. Only two drivers in the sample
(0.1%) had acuity worse than 20/100 (both were 20/200).
The vast majority of drivers in the sample (93.4%) had
contrast sensitivity scores of 1.5 or better. The distribution
of contrast sensitivity was displaced to worse scores with
increasing age. About 33% of drivers in the 90s had contrast
sensitivity scores worse than 1.5, whereas less than 7% of
drivers in the 70s and 80s had scores less than 1.5.
Visual processing speed as measured by the UFOV
subtest 2 or Trails B was in the normal range (<150 ms
for UFOV subtest 2; <2.47 minutes for Trails B) for just
more than half the sample (UFOV, 56.3%; Trails B, 62.2%).
Both visual processing speed tests showed a slowing in
processing speed with advancing age. For example, UFOV
scores were in the slowest processing speed category for
49% of drivers in the 90s, whereas only 7.4% of drivers in
their 70s had scores in the slowest category. Similar trends
were present for Trails B.
Half of drivers reported that they drove 7 days per week
(50.6%) and over a distance of more than 88 miles per week
(49.7%). The estimated number of trips drivers made per
week had wide individual variability. About two thirds of
the sample (68%) drove to four or fewer different places per
week. Drivers on average reported driving 9,528 miles per
year, with half the drivers driving less than or equal to 7,200
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OLDER DRIVERS, VISION, AND EYE CONDITIONS
Table 3. Visual Characteristics of the Sample of Older Drivers Aged ≥70 y Including Visual Acuity, Contrast Sensitivity, and Visual
Processing Speed
Age
Characteristic
n, %
Visual acuity (OU)
20/20 or better
Wt 20/20 to 20/40
Wt 20/40 to 20/100
Wt 20/100 to 20/200
Mean (SD), logMAR
Contrast sensitivity (OU)
≥1.8
≥1.5 to <1.8
≥1.2 to <1.5
<1.2
Mean (SD)
UFOV subtest 2 (ms)
<150
150–350
>350
Mean (SD)
Trails B (min)
<2.47
≥2.47
Mean (SD)
70–79 y old
80–89 y old
90–99 y old
878 (61.3)
457 (31.9)
96 (6.7)
1 (0.1)
0.04 (0.13)
243 (46.2)
231 (43.9)
51 (9.7)
1 (0.2)
0.08 ((0.14)
11 (28.2)
17 (42.5)
12 (30.0)
0 (0.0)
0.16 (0.15)
378 (26.4)
982 (68.6)
70 (4.9)
2 (0.1)
1.69 (0.13)
76 (14.4)
404 (76.7)
44 (8.4)
3 (0.6)
1.64 (0.14)
1 (2.5)
26 (65.0)
13 (32.5)
0 (0)
1.53 (0.13)
892 (62.3)
435 (30.4)
106 (7.4)
142 (123)
225 (42.7)
206 (39.1)
96 (18.2)
209 (149)
8 (20.5)
12 (30.8)
19 (48.7)
322 (155)
981 (68.7)
448 (31.3)
2.34 (1.29)
253 (48.1)
273 (51.9)
3.03 (1.66)
7 (17.5)
33 (82.5)
3.47 (1.18)
p Value
All Ages
<.0001
1,132 (56.7)
705 (35.3)
159 (8.0)
2 (0.1)
0.05 (0.14)
<.0001
455 (22.8)
1,412 (70.6)
127 (6.4)
5 (0.3)
1.67 (0.13)
<.0001
1,125 (56.3)
653 (32.7)
221 (11.1)
163 (136)
<.0001
1,241 (62.2)
754 (37.8)
2.55 (1.43)
Notes: UFOV = Useful Field of View; SD = standard deviation.
miles per year. All driving exposure variables had lower values with advancing decade of age, except for the number of
days driven per week, which did not change with age.
Discussion
With increases in the population aged 70 and older, there
has been widespread concern in the United States about the
safety of older adults who drive (6–9,26,27), because visual
functional impairments and eye conditions are common in
this population compared with younger adults (1–3,5). Yet,
results from this population-based study suggest that concerns that many older drivers have visual sensory impairments are highly exaggerated when viewed against the
reality of the situation. Ninety-two percent of drivers in our
sample had habitual visual acuity of 20/40 or better, with
20/40 being a common vision standard for licensure in various states. This means that the vast majority of the sample
would be viewed as safe drivers according to vision standard policies for licensure. Of the remaining 8%, all but two
drivers had visual acuity in the 20/50 to 20/100 range. Since
several decades of research indicate that drivers with visual
acuity between 20/50 and 20/100 do not have an elevated
crash risk (6), some states (eg, Maryland and Iowa) are
now allowing licensure for such drivers if they pass more
detailed driving evaluations. The remaining two drivers in
this sample had visual acuity worse than 20/100 but better than 20/200, which represents only 0.01% of the entire
sample. The results with respect to contrast sensitivity are
similar in that only a very small proportion of drivers more
than 70 years old (0.3%) had contrast sensitivity at severe
impairment levels (<1.2) that have been previously associated with increased MVC risk (18).
It is interesting to point out that at the time of this study,
the state in which this study took place (Alabama) did
not have a vision rescreening policy in place. This means
that participants’ visual acuity had not been screened for
licensure because their initial application for licensure,
when they were younger adults or when they moved into
the state. Because almost all drivers had good visual acuity, this begs the question as to whether policies mandating
vision rescreening at license renewal for older drivers are
cost-effective and actually remove dangerous older drivers
from the road. Only 2 out of 2,000 drivers had severe acuity
impairment. Three previous studies on vision rescreening
licensure policies for older adults report that these policies
are associated with lower collision fatality rates (28–30), but
another study did not find such a relationship except among
the oldest old (≥85 years) (31). Regardless, though, no previous study has clarified whether it is the vision screening
standard itself or going through the license renewal process
in general that is the mechanism mediating any observed
safety benefit.
Research has established that older drivers with cognitive
impairment are at an increased risk of MVC involvement
and impaired driving performance (21,32–34). Even cognitive screening tests, such as the MMSE (16), which are relatively gross screens for cognitive dysfunction, are associated
572
OWSLEY ET AL.
with impaired driving performance and increased crash risk
in older drivers (35–37). Although the primary focus of this
study was not on cognitive skills, it is still relevant to point
out that 98% of this sample of drivers aged 70 and older
had MMSE scores in the nondemented range (≥24), which
is consistent with a previous large sample study of older
drivers (38). Even for those in the 80s and 90s, 95% of these
drivers had MMSE scores of 24 or higher. This suggests
that the stereotypical view that many older adults who are
licensed and actually drive, particularly those aged 80 and
older, have serious cognitive problems is without basis.
Cataract surgery and IOL implantation is highly effective at restoring vision due to aging-related lens opacities.
This surgical procedure has also been shown to reduce
MVC risk by 50% (13). It is thus noteworthy that almost
half of this sample had already had cataract surgery and
IOL placement. With each advancing decade, the percentage of drivers who had cataract surgery increased, with
almost 85% of drivers aged 90 and older having undergone
cataract surgery.
The most prevalent visual disorder in this sample was
slowed visual processing speed, as revealed by both Trails
B and UFOV subtest 2; up to one third to one half of drivers in this sample had this visual processing impairment.
This is concerning because slowed visual processing speed
is a visual-cognitive screening test most consistently and
strongly associated with increased crash risk in older drivers (21,38–40). It is worth pointing out that visual processing speed is not an ability that is screened for at licensing
agencies in any jurisdictions in the United States (although
two states have examined it on an experimental basis)
(41,42).
This study suggests that drivers aged 90 and older
represent a very small percentage of the older adults behind
the wheel, about 2%. It is interesting that although these
persons are of very advanced age, in some ways they are
healthier than drivers under the age of 90; however, given
the cross-sectional nature of this analysis this, at least
partly, reflects a survival bias. The results suggest that they
tend to have fewer medical comorbidities, are less likely
to have cataracts, and less likely to be previous or current
smokers. On the other hand, they are more likely to have
visual functional deficits than younger senior drivers in that
they were more likely to exhibit slowed visual processing
speed and have visual acuity worse than 20/40.
Strengths and limitations of this study should be considered. This is the first population-based investigation
of a comprehensive set of both visual sensory and higher
order visual-cognitive processing screening tests in a large
population-based sample of older drivers. Screening tests
were selected based on their previously established relationships to MVC risk and impaired on-road driving performance. Second, the study incorporated a large sample of
drivers (N = 2,000) and had inclusion criteria that insured
that drivers were in fact licensed and actually had driven
in the recent past. Limitations must also be acknowledged.
The study was based on drivers in Alabama, and the generalizability of findings to other regions of the United States
remains to be determined. Yet, there is little reason to suspect that older drivers in Alabama have characteristics significantly different than the rest of the United States. The
researchers do not have information on the visual characteristics of the persons who were eligible but declined participation or those who they could not speak with on the phone to
determine eligibility; it is possible that the nonparticipants’
visual characteristics have different distributional properties than those who participated. This is acknowledged as a
study limitation. It might be argued that the nonparticipants
were more likely to have visual impairments. Yet, previous
research indicates that those who have visual impairments
are more likely to be nondrivers and thus not eligible for a
study focused on the visual characteristics of drivers (10,12).
The study sample consisted of primarily whites and African
Americans of non-Hispanic descent, so the relevance of the
researchers’ findings to the Hispanic, Asian, and other older
driver populations in the United States remains to be determined. Although the researchers did not assess peripheral
vision in this report, sensitivity throughout the visual field is
being addressed in a further study.
In conclusion, the researchers have described the visual
sensory and visual processing characteristics of older drivers in a state where no visual acuity rescreening program
for licensure renewal was in effect. However, what the
researchers found is that even without such a visual acuity rescreening program, the prevalence of significant visual
sensory impairment as measured by acuity and contrast sensitivity tests was very low, implying that many older adults
with visual sensory impairment self-regulate themselves off
the road and/or do so at the urging of their families, friends,
physicians, or other health care providers. The researchers
also found that the prevalence of slowed visual processing
speed is quite high in the older driver population, which
is concerning because it is not screened at reissuance of
licenses for older adults, yet has been associated in several studies with elevated MVC risk (21,38,40). Further
research will examine this sample prospectively in order
to determine which visual screening tests are the strongest
predictors of MVC risk in subsequent years.
Funding
This work was supported by the National Eye Institute and the National
Institute on Aging of the National Institutes of Health (R01EY18966,
P30AG22838); the American Recovery and Reinvestment Act of 2009; the
EyeSight Foundation of Alabama; the Able Trust; and Research to Prevent
Blindness, Inc.
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