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What is Low Vision?
Few people are totally without sight. Most classified as blind today actually
have some sight remaining and, thanks to developments in the field of low
vision, can be helped to make good use of it.
Anyone with reduced vision is visually impaired, and can have problems
functioning, ranging from minor to severe difficulty. There are two general
classifications of low vision in use today:
- partially sighted – visual acuity that with conventional prescription lenses
is still between 20/70 and 20/200 (a person with 20/70 eyesight must be 20 feet
away to see clearly an object that a person with 20/20 eyesight can see clearly
from 70 feet away);
- legal blindness – visual acuity that cannot be corrected to better than
20/200 with conventional lenses and/or the patient has a restricted field of
vision less that 20 degrees wide. (Note that some definitions of "partially
sighted" include the legally blind.)
Low vision impairments take many
forms and exist in varying degrees. It is important to understand that the
visual acuity alone is not a good predictor of the degree of the problem a
person is having. Someone with relatively good acuity (e.g., 20/40) can be
having a very hard time functioning, while someone with worse acuity (e.g.,
20/200) might not be having any real problems doing the things that they want to
do.
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