Articles about Eye Health and Disease 2002
Cataract Surgery Reduces the Rate
of Motor Vehicle Crash Involvement by Older Adults
(From Owsley C, PhD, et al., JAMA 8/2002;288:841-849.)
Cataract is a common condition in older adults, with studies showing
that about 50% of adults between 65 and 74 years of age have cataract.
Cataract causes blurred vision, glare problems, and reduced contrast
sensitivity (being able to distinguish between objects). African
American adults have a slightly higher rate of cataract, at 60%.
Older drivers with cataract have been found to have a history of recent
crash involvement, compared to those who are cataract-free.
Drivers over age 60 have been found to have the lowest crash rate when
measured on the basis of licensed drivers. However, when based on
the actual number of miles driven, older adults have a crash rate nearly
as high as the youngest drivers, who have the worst crash record (15
crashes per million miles traveled).
This study looked at the possibility that cataract extraction would not
only improve vision, but would also reduce the rate of motor vehicle
crashes due to improved vision. In the study, 277 patients with
cataract, aged 55 to 84 were enrolled from 12 clinics in Alabama.
They were divided into two groups, with one group deciding to have
cataract surgery, and the other group deciding not to have surgery.
Characteristics of the groups were as follows:
-
There was cataract in one or both eyes causing vision to be reduced
to 20/40 or worse.
-
No previous cataract surgery had been done in either eye.
-
Cataract surgery had been recommended by an ophthalmologist as a
treatment for the patient's visual problems, and the patient decided
to have, or not to have the surgery.
-
The patient was licensed to drive in the state of Alabama, and had
not given up driving.
Patients were excluded from the study in cases of amblyopia (lazy eye),
wheelchair required for mobility, diagnosis of dementia, Parkinson
disease, psychosis, or any disease that would prevent annual follow-up
visits.
At enrollment, 140 patients decided to have surgery, and 137 decided
against surgery. (Over the course of the study, an additional 34 patients
decided to have surgery. In these patients, results were divided into
before surgery and after surgery data). Visual function was tested
for each eye separately, and included visual acuity, contrast sensitivity,
and glare disability. Measurements of cognitive status, visual
processing speed, depression, and general health were assessed.
Patients returned for annual eye examinations, and a questionnaire
regarding driving difficulty was also given. In the 4-6 year
follow-up period, police-reported motor vehicle collisions were determined
for each patient. A determination of miles driven was also made.
Results:
There was found to be no difference in the rate of motor vehicle
accidents between the surgery group and the no-surgery group prior to
enrollment in the study. However, after cataract surgery, there
was a significant reduction in motor vehicle crashes in the surgery group
compared to the no-surgery group. The no-surgery group had a rate of
8.95 crashes per million miles, compared to 4.74 crashes per million miles
in the surgery group.
Furthermore, in the no-surgery group, the rate of crash rates from 5
years before enrollment to the end of the study showed a 72% increase in
crash rate. This was compared to much lower 27% increase in crash
rate for the surgery group.
In the surgery group, about 55% of patients had surgery in both eyes.
Interestingly, those patients who elected to have surgery expressed
serious difficulty with driving in the questionnaire, while those who
elected against surgery expressed less difficulty with driving.
Although the no-surgery patients believed that they had little difficulty
with driving, they had double the crash rate during the follow-up period
as those who had surgery. They surgical group of patients expressed
improved vision and driving ability after surgery.
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