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About
driving with BiOptics
By
Dr. Dennis Kelleher
Many
people with stable low vision want to drive a car. The vast majority of driving
decisions are based upon vision. This page discusses controversies about the
minimum visual acuity necessary for safe driving, and about driving with BiOptic
telescopes, to help people make decisions about driving. It also addresses ways
of learning to drive and seeking a license for those who cannot pass the
standard driver license vision screening test.
The
Decision to Drive
It
is critical that any low vision driver has a strong sense of responsibility and
willingness to voluntarily exercise good judgment by restricting themselves from
driving in situations they know to be unsafe. It is a fact, regardless of
whether it is fair or not, that all low vision drivers are judged by the safety
record of the entire group. It is important for us all to drive in the most
responsible way possible so all low vision drivers will not be in jeopardy of
losing their driving privilege.
Driving
is not for everyone, and neither is it for everyone in the general population.
Some people don't have the physical or mental ability, the temperament, the
desire, or the need to drive. The decision to drive is a very personal one that
must be made collaboratively between you, your eye doctor and your local
licensing agency.
Driving
Restrictions
Many
persons with albinism, for example, have central visual acuity in the range of
20/70 to 20/200 with standard corrective lenses. The visual acuity requirements
or screening standards used in the United States for driving without
restrictions ranges from 20/30 to 20/70, and the average is 20/40. Some states
will accept a visual acuity of 20/100 with corrective lenses for a restricted
driver's license with the recommendation of an eye doctor and demonstration of
the ability to operate a motor vehicle safely.
Restrictions
imposed upon the license may limit the driver to a geographic area or particular
routes, and may limit driving to certain hours of the day. The license may
require a particular vehicle using special equipment or devices. The driver
license agency may require more frequent and rigorous testing or special
training that is not required of other drivers.
In
order to meet the state requirement, some type of magnification device may be
necessary, such as a BiOptic telescope or Telecon system (a combination of
contact lenses and glasses) to increase the corrected visual acuity.
The
American Optometric Association endorses "individual evaluation of
individuals wearing spectacle-mounted BiOptic telescopes for driving."
However, the American Association of Motor Vehicle Administrators passed a
resolution in 1983 to ban all BiOptic drivers in all states. In 1984, the US
Department of Transportation expressed concern that some state departments of
transportation "discriminate against visually handicapped individuals
who wear BiOptic lenses." The DOT position is "that the use of BiOptic lenses on a person's eyeglasses should not automatically disqualify him
or her from being licensed to drive, [and] that all driver license applicants,
whether or not they wear BiOptic lenses, should be provided the opportunity to
take tests of vision, knowledge and driving skills." Even though the
AAMVA resolution appears to be contrary to the position of the DOT, the use of BiOptic telescopes is still not legal in some states. Those states are a
diminishing minority.
In
an effort to address the question of the minimum acuity necessary to drive
safely, studies have been conducted as early as 30 years ago comparing static
visual acuity, which is measured in a stable environment, versus dynamic visual
acuity, which is measured in an interactive environment that approximates the
driving task. Although dynamic visual acuity tests may predict driver safety
more accurately, most American States use static tests because of time and cost
factors.
Most
American States will permit persons with low vision to substitute documentation
from an eye doctor for the standard vision test. The US Department of Motor
Vehicles will want specific information about visual function such as:
-
corrected
and uncorrected visual acuity;
-
peripheral
visual fields;
-
stability
of eye condition;
-
depth
and color perception;
-
ability
to coordinate hand, neck, and eye movement;
-
contrast
sensitivity, glare recovery, and luminance.
Low
Vision and Driving
Depressed
central visual acuity, or low vision, is one of the characteristics of albinism.
However, albinism is a genetic condition that is stable, so the vision does not
deteriorate over time. People with albinism usually have normal color perception
and near normal peripheral visual fields. In addition, albinism is not usually
accompanied by scotomas (blind spots) within the visual field. There are
other stable low vision conditions that are equally suitable for driving.
- scotoma (sko-to'ma) An island-like blind gap in the
visual field. Taber's Medical Dictionary.
Even
the normally sighted driver does not resolve details on a continuous basis at
the 20/20 acuity level while driving. The driver uses 20/20 acuity only as a
response to low resolution stimuli. Adequate peripheral vision is more important
than central acuity, and persons with tunnel vision are unable to drive safely
even if they have 20/20 central acuity.
All
persons with low vision who drive must compensate for a reduced safety margin,
which results from a delay in spotting hazards. Studies of visually impaired
drivers found that these drivers had an accident rate 1.3 times higher than that
of non-disabled drivers. But these same studies found that visually impaired
drivers had an accident rate only half that of other medically disabled driver
groups such as those with orthopedic disabilities, hearing impairments and
seizure disorders. It was also found that visually impaired drivers had fewer
citations than non-disabled driver.
Driving
is a privilege and not a right. US DMV records indicate that the characteristics
of drivers who are most likely to be involved in an accident are those who are
impulsive, emotionally unstable, overly aggressive, angry, inattentive, slow to
react, substance abusers, risk takers, inexperienced or new drivers, teenagers
younger than 18, or seniors over age 75.
Driving
Skills
In
the US, the licensing agency will use the same performance standards to evaluate
the low vision driver as it uses to assess driving skills in the general
population. These will generally include vehicle speed control, shifting and
braking, depth and spatial perception, steering, use of mirrors, backing up and
parking, knowledge of rules of the road, and courtesy.
BiOptic
-
Use
non-visual cues.
-
Keep
eyes moving and be alert.
-
Check
mirrors frequently.
-
See
the whole picture and anticipate what the other driver will do.
-
Be
sure you are seen and communicate your intentions.
-
Follow
at safe distances, three or four seconds behind the proceeding vehicle at
the current speed.
-
Watch
for a last resort escape route.
-
Choose
less demanding routes and know where to go in advance.
-
Check
traffic over your shoulder before changing lanes.
-
Look
backwards before backing up.
-
Use
other aids as necessary (hats, visors, tinted lenses, magnifiers, etc.).
New
drivers, whether or not they have a lower visual acuity, often experience
typical problems. One common example is the difficulty almost all new drivers
encounter when trying to steer the vehicle straight at high speeds the first
time they drive on a highway. Because the new driver tends to look directly in
front of the vehicle instead of focusing on a point in the distance, the driver
'oversteers', and the vehicle may move back and forth or in and out of the
traffic lane. Patience and practice will allow the new driver to overcome these
tendencies.
BiOptic
The
most popular low vision aid utilized for driving is the BiOptic telescope. The BiOptic consists of a miniature Galilean or Keplerian telescope that is positioned in the
upper portion of a carrier lens. The carrier lens, which incorporates the
individual's standard refractive correction, is conventionally mounted in the
frame. This arrangement allows the user to look through the telescopic portion
for spotting and magnifying distant objects while permitting a rapid change in
fixation to the large carrier lens for general viewing of the entire visual
environment. The most commonly used BiOptic magnifications prescribed for
driving are the 2.2X, the 3.0X and the 4.0X. The BiOptic telescope is a lens
system that requires time and training for an individual to become proficient in
its use. The following is an effective BiOptic training sequence that has been
used by many individuals.
-
Rapidly
locate stationary objects while you are still.
-
Rapidly
locate moving objects while you are still.
-
Rapidly
locate moving objects while you are moving (preferably as a passenger in a
car).
-
Develop
accurate visual perception skills to evaluate the environment rapidly.
A
BiOptic is used only intermittently, never constantly, during driving. The BiOptic is a spotting device. The amount one spots through the
BiOptic varies
depending on the type of driving. Generally the faster one is going, the
more often the BiOptic will be used for spotting distant objects. The majority
of driving tasks will use the vision through the carrier lens. Maximizing eye
movement instead of head movement can decrease response time.
The
Controversy over BiOptics
Critics
of using BiOptics for driving raise several concerns including:
-
small
visual field through the BiOptic telescope;
-
ring
scotoma causing a hazardous blind spot;
-
vibration
and speed blur;
-
telescopic
parallax (shifting of view) and depth perception;
-
difficulty
of using the BiOptic with mirrors;
-
critical
adjustment of the BiOptic frame and angle of the lens.
Doctors experienced in
fitting BiOptic drivers respond:
- BiOptic drivers do not drive continuously through the
BiOptic telescope but rather use the telescope intermittently much the way
all drivers glance briefly into rearview mirrors. Perhaps less than 5% of
the driving time is done through the BiOptic system. Most BiOptic drivers
use the BiOptic for only 1 to 2 second intervals to see distance detail such
as a traffic sign.
- Additionally, when a BiOptic driver scans into the BiOptic,
the driver still maintains an awareness of field of vision in the same
manner that a non-BiOptic driver when looking into the rear mirror is still
aware of peripheral visual information. The sudden movement of a passing car
will still be perceived by a driver while viewing briefly in either a mirror
or BiOptic.
- Slight obstructions in the visual field may occur
intermittently for all drivers such as when a driver looks into the rearview
mirror. These occur for only 1 to 2 seconds and are lessened by the normal
movements of our eyes and head. The constant motion and scanning of the
driver's eyes and head prevents functional ring scotomas.
- The information we receive through rearview mirrors, such
as an approaching car, is usually not so detailed as to require the use of
the BiOptic system, However, BiOptic systems are focused for optical
infinity for driving which allows either their carrier lenses or the BiOptic
to be used to view through the mirrors.
- Speed and vibration may slightly affect the vision of all
drivers. Since BiOptic drivers only utilize the BiOptic intermittently for 1
or 2 seconds, vibration and motion blur are easily managed. BiOptic drivers
quickly learn to appreciate differences in image movement and relative
distance perception through the BiOptic.
- Today's BiOptics are durable and easily adjusted. BiOptics
are fitted at a slight angle up so that on slight downward gaze, the BiOptic
becomes parallel with the road. Highly trained low vision specialists fit
BiOptics.
The key to understanding the ability of mildly visually
impaired individuals to safely drive with BiOptics is the concept that vision is
a dynamic process. Ours eyes and head move constantly preventing stationery
blind spots and our visual system learns to adapt to new ways of processing
information. It is the ability of the brain to adapt, not our eyes that allows
safe BiOptic driving.
"All great truths begin as blasphemes." - George
Bernard Shaw
For
more technical information regarding concerns over BiOptic driving, and/or questions
about
research:
ask
a
senior
and
experienced
Optometrist
here. If you have
a concern or question regarding the use of a
BiOptic during the driving task, please post
it here. ... And for
more on controversies, click
here.
Conclusion
If
you have stable low vision, and are highly motivated to drive, you can do it as
long as your eye specialist verifies that you meet the visual prerequisites for
your location, and you put forth the time and effort to learn how to do it
safely.
—
Richard Windsor O.D. F.A.A.O.
Indianapolis
Office (317) 844-0919
—
Dennis Kelleher, Ed.D.
Special
Education Consultant, Office of the Director, Special Education Division
California Department of Education 428 J Street, Suite 550 Sacramento, CA 95814 916-327-0842 Voice 916-445-4550 FAX
—
Charla McMillan, M.S.
Past
President, NOAH
To
see
a
detailed
MS
PowerPoint
presentation
given
by
Dr.
Dennis
Kelleher
on
factors
concerning
driving
with
BiOptic
Telescope
Systems,
click
here.
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