Over three million people in the United States do not
have normal vision even with eyeglasses or corrective
lenses. These people are considered visually impaired.
Visual impairment may be caused by a number of eye diseases,
including age-related macular degeneration, diabetic
retinopathy, glaucoma, and cataracts.
Although many eye diseases can be diagnosed and treated
by your ophthalmologist, some may result in unavoidable
loss of central (reading) vision, peripheral (side)
vision, or both. Accidents or inherited ocular disorders
may also produce vision loss which cannot be medically
Visual impairment can range from mild to severe. Federal
regulations define a certain level of visual impairment
as "legal blindness," not to be confused with
total blindness. Most of the approximately one million
Americans defined as "legally blind" retain
some useful vision.
How is sight measured?
Central or reading vision is customarily measured using
an eye chart. The results are recorded as a pair of
numbers called "visual acuity." The first
number is the testing distance measured in feet; the
second number is the distance from which a normal eye
should see the letter clearly. People with a visual
acuity of 20/20 can see certain sized letters at a distance
of 20 feet. An individual with a visual acuity of 20/60
can only see at 20 feet letters which a normal eye can
identify at 60 feet. The larger the second number, the
lower your visual acuity.
Side vision--which can be even more important than
central or reading vision for many daily activities--can
also be measured by an ophthalmologist. Normal eyes
can recognize objects over an area measuring at least
140 degrees (almost half a circle). A person with a
much narrower range of side vision may have trouble
walking or recognizing people in a large room, even
when his or her central vision is excellent.
Ophthalmologists can administer tests to measure other
aspects of visual function. Tests may include eye movement,
color and contrast vision, stereoscopic (three-dimensional)
vision, and adjustment to light and dark. These tests
allow your ophthalmologist to identify specific visual
conditions and describe their severity.
What is legal blindness?
When your best corrected central visual acuity is 20/200
or worse in your better eye, or your side vision is
narrowed to 20 degrees or less in your better eye, you
are considered legally blind even though you may still
have some useful vision. You may qualify for certain
government benefits and receive assistance from public
and private organizations.
What is visual impairment?
If neither of your eyes can see better than 20/60 without
improvement from eyeglasses or corrective lenses, you
may be defined as visually impaired. Limitation of side
vision, abnormal color vision, double vision, poor night
vision, and loss of vision in one eye may also determine
What is a visual disability?
People who are unable to perform certain tasks because
of their visual impairment are usually "visually
disabled." An exact rating or quantification of
the disability is necessary for a person to receive
workman's compensation, insurance disability benefits,
legal claims, or certain forms of government assistance.
Visual disability is expressed in percentages, which
are used by insurers, the courts, and government agencies
to determine how much the whole person is disabled by
his or her visual handicap. For example, total loss
of vision in both eyes is a 100% disability of vision,
but only an 85% disability of the whole person.
What can you do about your visual impairment?
Have your ophthalmologist help you understand the
cause and learn whether the impairment is temporary,
stable, or likely to progress.
Make use of rehabilitation programs, devices, and
supportive services. These include counseling, large
print and audio publications, optical and electronic
magnifiers, mobility training, and non-optical aids
such as improved lighting devices, large-face clocks,
and special kitchen tools.
Join a local support group and a national association
for people with similar eye problems.
Ask your ophthalmologist to refer you to the appropriate
state and local agencies for the visually disabled.
These agencies can help you obtain a handicapped
parking designation, low-vision services, and possibly
Social Security and Department of Veterans Affairs
benefits. Federal and state income taxes can be
reduced through an extra exemption allowed to "legally
blind" individuals. Some communities may offer
a reduction in property taxes as well.
Continue seeing your ophthalmologist for regular
checkups. Your eye disorder may change, so its treatment
may also need to be changed. Because eyes can be
affected by more than one disease, it is especially
important that any new problems be detected and
treated promptly in order to preserve your remaining
Request the American Academy of Ophthalmology brochure
on low vision, and resource list of referral services,
large print and recorded reading materials, devices,
and support groups