Transcript Visual Impairments - Michigan Crossroads Council

By Lacey Curtis
EDN 410
November 14, 2009
The term Visual Impairment describes any kind of vision
loss whether it’s a person who cannot see at all or
someone who has partial vision loss
Visual impairments are usually defined by legal or
educational standards. The terms legal blindness, total
blindness, partially sighted, and low vision are all legal
terms used to refer to visual impairments.
From an educational viewpoint, the term visual
impairment is defined less by visual acuity and more by
educational tasks such as reading. Functional vision is
another educational term which refers to the way a
person uses their vision as well as the amount of vision
that person has.
http://kidshealth.org/teen/diseases_conditions/sight/visual_impairment.html
Teaching Students Who Are Exceptional, Diverse, & At Risk
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Legal Blindness describes a person who has less than
20/200 vision in their best eye or a very limited field of
vision (20 degrees at its widest point).
Total Blindness refers to a small group of individuals
with visual impairments who are unable to see
anything, including objects or light sources.
Partially Sighted is a phrase that was formerly used to
describe individuals with a visual acuity in the range
of 20/70 to 20/200. This term is not presently used as
widely as it once was.
Low Vision is the present term typically used for
individuals with visual acuity in the range of 20/70 to
20/200. These individuals continue to have difficulty
with vision even with corrective lenses (glasses).
http://www.nichcy.org/Disabilities/Specific/Pages/VisualImpairment.aspx
Teaching Students Who Are Exceptional, Diverse, & At Risk
http://www.lensdoctors.net/eye-health/eye-anatomy.html
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IRIS: Pigmented tissue lying behind cornea
that (1) gives color to the eye, and (2)
controls amount of light entering the eye
by varying size of black pupillary opening;
separates the anterior chamber from the
posterior chamber.
CORNEA: Transparent front segment of the
eye that covers iris, pupil, and anterior
chamber, and provides most of an eye's
optical power.
PUPIL: Variable-sized, circular opening in
center of iris; it appears as a black circle
and it regulates the amount of light that
enters the eye.
LENS: Natural lens of eye; transparent
intraocular tissue that helps bring rays of
light to focus on the retina.
SCLERA: The white of the eye; a protective
fibrous outer layer covers all of the eyeball
except for the part covered by the
cornea.
CILIARY BODY: A muscular ring under the
surface of the eyeball; helps the eye focus
by changing the lens’s shape and also
produces aqueous humor.
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CHOROID: The vascular layer between
the sclera and the retina; the blood
vessels in the choroid help provide
oxygen and nutrients to the eye.
OPTIC NERVE: Largest sensory nerve of
the eye; carries impulses for sight from
retina to brain.
MACULA: Small, specialized central area
of the retina responsible for acute
central vision.
RETINA: Part of the eye that converts
images into electrical impulses sent
along the optic nerve for transmission
back to the brain. Consists of
many named layers that include rods
and cones.
VITREOUS: Transparent, colorless,
gelatinous mass; fills rear two-thirds of the
interior of the eyeball, between the lens
and the retina.
http://www.lensdoctors.net/eyehealth/eye-anatomy.html
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Visual acuity: This is the
measurement of how
clearly we see. A child’s
acuity is measured in
each eye individually and
in both eyes working
together. A loss of acuity
can range from mild to
severe and differ in both
eyes. Glasses may be
prescribed to help
improve visual acuity.
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Visual field: This is the total
area that can be seen
without moving the head
or eyes. A loss of visual
field can occur on one
side (hemianopsia) or on
the upper or lower field.
While others may
experience spots of poor
vision (scotomas) within
their visual field. With
some eye conditions, a
loss of peripheral vision
(tunnel vision) or a central
visual field loss is present.
http://www.nhbvi.com/Agenda/Goal1/Book1/typesanddegrees.html
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Myopia (Nearsightedness): The image of a distant object
does not focus on the retina but instead in front of it, which
makes it appear blurry. This can result from having an
elongated eyeball, a lens that is too strong, or a cornea
that is excessively curved. The child can see things that are
near but not farther away.
Hyperopia (Farsightedness): The image focusing point is
behind the retina which results in straining to focus correctly,
especially at close distances. This can result from shortness
of the eyeball, a lens that is weak, or a cornea that is mostly
flat. The child can see things well at a distance, but not up
close or near.
Astigmatism: This error occurs when the cornea has a
cylindrical curvature which prevents light rays from focusing
on one point on the retina. This results in both near and far
objects sometimes appearing blurry. Astigmatism often
occurs in conjunction with Myopia and Hyperopia.
http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
Ocular motor impairment occurs when a
child has difficulties with the muscles
controlling the eyes. Eye muscles control
how well a child is able to fixate, follow,
search, and converge with their eyes. As
the muscles work together, the child is
able to see three dimensional images.
Surgery is an option to help a child with
ocular motor difficulties.
http://www.nhbvi.com/Agenda/Goal1/Book1/typesanddegrees.html
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Albinism: This is an inherited condition in which the individual has
decreased pigment that causes abnormal optic nerve development.
As well as having a decreased visual acuity, these children may also
be sensitive to light. Tinted lenses, glasses and low vision aids can all
help to decrease light sensitivity and maximize vision.
Amblyopia (lazy eye): A weakening of the image of one eye typically
due to that eye having a much poorer acuity or being turned in or
out. These children may have some functional field of vision loss and
poor or no depth perception. Placing a patch on the stronger eye
and using glasses may be prescribed.
Cataracts: Characterized by opacity or cloudiness of the lens. Vision
is affected since light is unable to pass through the lens. Some
cataracts get worse with time while others remain unchanged.
Cataracts can occur in one eye (unilateral) or both eyes (bilateral).
These children may have blurry vision, poor color vision, light sensitivity,
reduced visual acuity, or nystagmus. Surgery is sometimes
recommended to remove cataracts depending on how severe they
are.
Coloboma: This is a birth defect that causes a cleft in the pupil, iris,
lens, retina, choroid, or optic nerve. This condition can result in
reduced acuity and field of vision loss if the damage extends to the
retina.
http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
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Glaucoma: A condition which is characterized by increased pressure
in the eye caused by blockage of normal flow of fluid in the eye.
Changes in pressure can cause the child with glaucoma’s vision to
fluctuate. Glaucoma may also cause peripheral field loss, poor night
vision, and sensitivity to light. If glaucoma goes untreated, damage to
the optic nerve can result.
Nystagmus: Involuntary movement of the eye which can be
horizontal, vertical, circular or a combination. A child with nystagmus
has a hard time maintaining fixation on objects since their eyes are
frequently moving. This results in reduced visual acuity and fatigue. By
turning the head or eyes to a certain position known as the “null point”,
nystagmus can be minimized. This “null point” is different for each
person.
Optic Nerve Atrophy: When damage or degeneration to the optic
nerve which carries visual signals to the brain takes place, this condition
occurs. Depending on the severity of the damage, vision loss varies
and may include blurred vision, poor color and night vision, and
sensitivity to light.
Optic Nerve Hypoplasia: Sometimes the optic nerve under develops
while a fetus is in utero, which results in a small optic nerve and visual
impairment. The degree of visual impairment can vary significantly, but
there is typically acuity loss. This condition is sometimes associated with
other conditions.
http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
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Retinitis Pigmentosa (RP): A hereditary and degenerative condition
of the retina which results in loss of peripheral vision or “tunnel
vision”. The condition usually starts with difficulty in seeing in dimly lit
areas and progresses to significant visual impairment.
Retinoblastoma: In this condition, a cancerous tumor grows on the
retina. Aggressive treatment of all tumors through laser, radiation,
and/or chemotherapy is required. As retinoblastoma progresses,
an enucleation or removal of the eye is sometimes needed. If an
eye is removed, the child will lose their depth perception.
Retinopathy of Prematurity (ROP): A condition common in children
who were premature infants and required high concentrations of
oxygen at birth. As the normal development of the blood vessels of
the retina is interrupted, scarring and detachment of the retina can
result. The child with ROP may have a decreased visual acuity and
refractive errors.
Strabismus: In this condition, a muscle imbalance prevents both
eyes from being able to look directly at an object at the same time.
Different types of strabismus include: esotropia (an inward turn),
exotropia (an outward turn), hypertropia (an upward turn), and
hypotropia (a downward turn).
http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
http://www.brighthub.com/education/special/articles/35103.aspx
Cortical visual impairment or Neurological visual
impairment (NVI) is not caused by damage or a
condition of the eye. Instead, it is caused by
damage to the visual cortex of the brain which
processes visual information. The vision loss can
be mild or severe, and can also vary from day to
day. Cortical visual impairment may be
temporary or permanent. Children with a
cortical visual impairment may also have
cerebral palsy, seizure disorder, and
developmental delays as a result of the damage
to the brain. People with this type of impairment
may have trouble recognizing faces, interpreting
drawings, perceiving depth, or distinguishing
between background and foreground.
http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
http://www.afb.org/Section.asp?SectionID=40&DocumentID=2139
Simple refractive errors (nearsighted,
farsighted, astigmatism) make up the majority
of common visual impairments.
 More boys than girls are visually impaired.
 The rate at which visual impairments occur in
individuals under the age of 18 is 11.2 per
1,000.
 Severe visual impairments (legally or totally
blind) occur at a rate of .06 per 1,000.
 Many visual impairments can occur at any
age, however, over two-thirds of those with
visual impairment are over age 65.
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http://www.napcse.org/exceptionalchildren/visualimpairments.php
http://www.brighthub.com/education/special/articles/35103.aspx
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In order to assist students with visual impairments get
through printed material in class, you will need a
combination of materials. Books in Braille, readers, and
recorded books and class lectures will all help.
Modify assignments when possible in order to allow
students to become more independent.
Teach other students how to help guide the student
with a visual impairment.
Encourage students with visual impairments to use their
sense of touch, and provide tactile models when
possible.
Describe people and happenings in the classroom
verbally for the visually impaired student.
If possible, assign a peer “visual translator” to work with
the visually impaired student. The visual translator
verbally describes visual images to the student to assist
in their learning.
http://glencoe.com/sec/careers/teacher/strategies.shtml#f
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A nonprofit research development organization
entitled CAST (Center for Applied Special Technology)
has been researching Universal Design of Learning
since 1984.
UDL provides a blueprint for creating flexible goals,
methods, materials, and assessments that
accommodate learner differences.
"Universal" does not imply a single optimal solution for
everyone. Instead, it is meant to underscore the need
for multiple approaches to meet the needs of diverse
learners.
Embedded features that help those with disabilities
eventually benefit everyone. UDL uses technology's
power and flexibility to make education more inclusive
and effective for all.
When using the approach of Differentiated Instruction,
it is important to provide different approaches in
process, product, and content.
www.cast.org
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CAST has a software program titled CAST eReader
available for schools to install to assist standard
students as well as learning disabled students. Within
this program is a function called eTrekker which helps
students to organize their Web searches. The student
types in a search question and eTrekker checks their
spelling and identifies search terms to use from the
question. After the list of 10 websites comes up, the
student can select a site and click on “read” to have
the information read aloud to them. The program
saves the research question, key terms, websites
visited, and any notes created by the student using
the onscreen notepad. With some assistance, this
program could really benefit the visually impaired
student, as well as be functional for the standard
student.
http://techplan.org/ci2005/udl_def_and_examples.pdf
 Teaching
computer skills to visually impaired
children: A concept based approach
http://www.tsbvi.edu/technology/computerskills.htm
 Council for Exceptional Children: The voice
and vision of special education
http://www.cec.sped.org
 Visual impairments and Multiple impairments
http://www.tsbvi.edu/recc/mivi.htm
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Textbook Teaching Students Who Are Exceptional, Diverse, & At Risk
http://www.nichcy.org/Disabilities/Specific/Pages/VisualImpairment.
aspx
http://kidshealth.org/teen/diseases_conditions/sight/visual_impairme
nt.html
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http://www.nhbvi.com/Agenda/Goal1/Book1/commoncauses.html
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http://www.lensdoctors.net/eye-health/eye-anatomy.html
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http://www.brighthub.com/education/special/articles/35103.aspx
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http://www.afb.org/Section.asp?SectionID=40&DocumentID=2139
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http://www.napcse.org/exceptionalchildren/visualimpairments.php
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http://glencoe.com/sec/careers/teacher/strategies.shtml#f
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www.cast.org
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http://techplan.org/ci2005/udl_def_and_examples.pdf