Download Can You See Well Enough to Drive?

October 25, 2010
Can You See Well Enough to
Drive?
S. A. Helton
St. Joseph Mercy Hospital
It’s late October and many seniors in the community
have either already hit the road or are planning to in
the next couple of weeks. For nearly 20 years, Tom
and Lucy have been retired road warriors. They live in
Michigan but drive to Texas, Maryland and Florida
several times a year to visit their kids and grandkids.
Now in their late 70s, each is quietly beginning to wonder: Do
I see well enough to drive?
Eye problems such as macular degeneration, cataracts, glaucoma and diabetic retinopathy become increasingly common
after age 50. Visual acuity is also affected by age, and this is the
vision function most commonly tested when a license is issued
or renewed.
If you can read a lighted stationary chart at a 20/40 level or
better, you can usually renew your license. If your vision is
less than 20/40, your license will indicate that you must wear corrective lenses to drive
legally.
Actually, even with 20/40 vision, you have to get three times closer to a street sign to
read it compared to a person with normal vision. And that doesn’t take into account
conditions such as rain, fog or darkness.
What is required, though, is ability to read traffic signs rather than street signs and, more
importantly, to react properly. Experts agree that safe driving involves many other factors such
as visual field, depth perception, contrast, color, glare sensitivity and night vision.
VISUAL FIELD
Most states have rules denying a license to a person with a major impairment of peripheral vision.
Glaucoma, cataracts and retinal disorders all affect peripheral vision. One study found that
only about half of persons with loss of peripheral vision were aware of their limitations.
And they had twice as many accidents and traffic violations as subjects with normal
peripheral vision.
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If you have questions about programs and services of St. Joseph Mercy Port Huron, please
visit us online at: mymercy.us. To find a physician near you, call toll-free 1-888-MERCYME.
Do you see well enough to drive?
- continued
USEFUL FIELD OF VISION
Useful field of vision takes into consideration not only what a person sees in peripheral
vision but how he or she perceives and processes that information. In other words, it
combines vision and attention, making it one of the most meaningful measures of driving
ability in an older person.
Head injury, a stroke and neurological diseases such as multiple sclerosis can effect these
skills, and a computer-administered test is available (though not widely used) to assess visual
attention and processing abilities.
NIGHT VISION
Even though your eyes may show no serious problems when tested in the doctor’s office,
you are not likely to see as well as a younger person when driving at night. The pupil of
the eye shrinks with age and doesn’t dilate as effectively. As a result, the retina of an 80year-old receives significantly less light than that of a 20-year-old.
With aging, the cornea and lens of the eye also become gradually less clear, causing
scattering of light inside the eye and increased glare when exposed to bright lights. There
is also a loss of sensitivity to contrast, making it harder to see objects on the road at night.
You may not even notice these age-related changes, but an early cataract can make glare
problems worse. And the intra-ocular lens that is implanted after cataract surgery further
increases sensitivity to glare from bright headlights or the sun.
Age-related macular degeneration, diabetic retinopathy and retinal tears can also effect night
vision. Driving into bright headlights or a low sun in the morning or evening can cause
photostress, temporarily bleaching the retina and causing a dramatic drop in visual acuity.
Young, healthy persons with no macular or retinal problems will recover quickly; an older
person with macular degeneration may take several minutes.
DEPTH PERCEPTION
Ability to correctly judge distances is a crucial part of driving. Drivers with a significant
difference in corrected visual acuity between the two eyes, as well as those who have lost
vision in one eye, may show reduced depth perception.
Many states screen drivers for depth perception, and one study found that drivers whose tests
showed even fairly small reductions in depth perception or reduced visual acuity when
confronting glare were likely to restrict their driving.
Most Americans put high value on their ability to hit the road in a motor vehicle, and loss
of driving privileges usually leads to increased isolation and social and emotional consequences.
Even so, many seniors do eventually put restrictions on themselves–limiting driving at night,
in bad weather or rush hour conditions. Even if they do not fully recognize their impairments,
these individuals apparently feel increased anxiety about driving in certain situations.
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Page 2
remarkable medicine. remarkable care.
If you have questions about programs and services of St. Joseph Mercy Port Huron, please
visit us online at: mymercy.us. To find a physician near you, call toll-free 1-888-MERCYME.
Do you see well enough to drive?
- continued
When it comes to visual attention, processing speed, motion sensitivity and divided
attention skills, some seniors may need help identifying their limitations. The Useful
Field of Vision test is an effective screening tool, but even more important is counseling
by a physician, family member or friend.
To find a physician near you, call toll free: 1-800-MERCYME, or visit St. Joseph
Mercy online at: mymercy.us.
Annual Cancer Care Symposium
Planned
S. A. Helton
St. Joseph Mercy Hospital
For more than a quarter of a century, St. Joseph Mercy Port Huron and its Mercy
Regional Cancer Center has been the area’s leader in providing cancer care services throughout the Blue Water and Thumb communities. To continue to provide
for the advancement of cancer care, it will host the 19th Annual Cancer Care
Symposium, titled: “2010 Oncology Updates”.
This year’s event will be held Saturday, November 13, 2010 at St. Joseph Mercy Hospital’s
Baggot Street Café, located at 2601 Electric Avenue, Port Huron. The event registration
begins at 7:30 a.m. and will conclude at 2 p.m. The event is free to St. Clair County
Continuing Medical Education (CME) Consortium members through the St. Clair
County Medical Society.
The symposium is designed to provide primary care physicians, radiation oncologists,
surgeons, medical oncologists and other allied health care professionals, who treat or care
for patients with cancer, detailed information on molecular testing, primary brain cancer,
paraneoplastic syndromes, pediatric oncology, and oncology and health care legislation.
An update regarding the work of the Mercy Cancer Network will also be provided.
Six AMA PRA Category 1 Credits will be offered. The award winning St. Joseph Mercy
Port Huron is the only oncology program in the county to host an annual cancer care
symposium providing continuing clinical cancer education.
The information provided in Healthy
Living is for educational purposes only.
Speak with your doctor directly about any
issues that effect your health.
Editor: Stephanie Armstrong-Helton
810-984-1166
[email protected]
mymercy.us
Local cancer and regional oncology experts will present on this broad range of topics.
Registration deadline is Wednesday, November 10. For more information about the event,
cost to attend (if applicable); or to make a reservation, please call 810-985-9502.
St. Joseph Mercy Hospital is the first hospital in the St. Clair County to be awarded the
prestigious Commission on Cancer (CoC) Outstanding Achievement Award [2008].
For more information regarding the Mercy Regional Cancer Center, call toll-free 1888-MERCYME, or visit St. Joseph Mercy online at: mymercy.us.
St. Joseph Mercy Port Huron O 2601 Electric Avenue, Port Huron, MI 48060 O mymercy.us
If you have questions about programs and services of St. Joseph Mercy Port Huron, please
visit us online at: mymercy.us. To find a physician near you, call toll-free 1-888-MERCYME.
mymercy.us
St. Joseph Mercy Port Huron O 2601 Electric Avenue, Port Huron, MI 48060 O mymercy.us