2. Visual Impairment
Definition
According to the US Department of Education
(2006), Visual Impairment including blindness
means an impairment in vision that, even with
correction, adversely affects a child’s educational
performance. The term includes both partial sight
and blindness.(p.1265)
3. Blindness Definition
A person, who is blind according to the
Centers for Disease Control (2005), has a
visual acuity worse than 20/400, with the
best possible correction, or visual field of 10
degrees or less. (p.1)
4. Low Vision Definition
Corn (1989) stated that low vision is a level of
vision, with standard correction hinders an
individual in planning and/ or execution of a
task, but which permits enhancement of the
functional vision through the use of optical or
nonoptical devices, environmental
modifications and /or techniques. (p.28)
5. Legally Blind Definition
The American Foundation for the Blind
stated that legally blind is when the central
visual acuity of 20/200 or less in the better
eye, with best correction, or a diameter of
normal field that does not subtend or angle
greater than 20 degrees at its widest point.
(p.1)
6. Visual Efficiency
Definition
Visual efficiency- This is how well
people can use their sight.
It is influenced by many factors,
including the person’s acuity and
peripheral vision, environmental
conditions and psychological
variables.
7. Residual Vision
Residual vision – the amount and degree of
vision a person has functional use of, despite a
visual disability.
8. Peripheral Vision
Peripheral vision is the width of a person’s field
of vision, or the ability to perceive objects
outside of the direct line of vision.
This aspect of vision helps people to move
freely through their environment.
It helps them to see large objects and
movement.
Severe limitations in peripheral vision is
sometimes called tunnel vision or restricted
central vision.
9. Categories of Visual
Impairment
Normal acuity
Impaired acuity
Normal vision field
Impaired peripheral fields
Impaired lower visual field
“Blind spots” in the visual field
Blind