visual disabilities
DESCRIPTION
Visual Disabilities. Learners with Blindness or Low Vision. Overview- Visual impairments seem to evoke more awkwardness than most other disabilities. One reason is that blindness is visible, whereas we often do not realize that a person has impaired hearing - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/1.jpg)
Visual Disabilities
![Page 2: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/2.jpg)
Learners with Blindness or Low Vision
• Overview- Visual impairments seem to evoke more awkwardness than most other disabilities.
• One reason is that blindness is visible, whereas we often do not realize that a person has impaired hearing
• Blindness is the least prevalent of all disabilities, at least in children
![Page 3: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/3.jpg)
Definition and Classification
• Legal Definition- legally blind- A person who has visual acuity of 20/200 or less in the better eye even with correction or has a field of vision so narrow that its widest diameter subtends an angular distance no greater than 20 degrees.
• Low vision- Visual impairments are not so severe that they are unable to read print of any kind
• Educational Definition- (low vision)- someone who has difficulty accomplishing visual tasks, even with corrective lenses, but who can enhance his or her ability to accomplish these tasks with the use of compensatory visual strategies
![Page 4: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/4.jpg)
Prevalence
• Blindness is primarily an adult disability
• Blindness is approximately one-tenth as prevalent in school-age children as in adults
• About .05 percent of the population ranging from 6 to 17 years of age is classified by the federal government as “visually impaired”
![Page 5: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/5.jpg)
Anatomy and Physiology of the Eye
• Cornea- A transparent cover in front of the iris and pupil in the eye; responsible for most of the refraction of light rays in focusing on an object
• Aqueous humor- A watery substance between the cornea and lens of the eye
• Pupil- The contractile opening in the middle of the iris of the eye
• Iris- The colored portion of the eye; contracts or expands, depending on the amount of light striking it
![Page 6: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/6.jpg)
Anatomy of the Eye cont.
• Lens- A structure that refines and changes the focus of the light rays passing through the eye
• Vitreous humor- A transparent, gelatinous substance that fills the eyeball between the retina and the lens of the eye
• Retina- The back portion of the eye, containing nerve fibers connected to the optic nerve
• Optic nerve- The nerve at the back of the eye, which sends visual information back to the brain
![Page 7: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/7.jpg)
Anatomy of the eye
![Page 8: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/8.jpg)
Measurement of Visual Ability
• Snellen Chart- Used in determining visual acuity; each row corresponds to the distance at which a normally sighted person can discriminate the letters
• Visual efficiency- How well one uses his or her vision, such as control of eye movements, attention to visual detail, and discrimination of figure from background
• Functional visual assessment- An appraisal of an individual’s use of vision in everyday situations
![Page 9: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/9.jpg)
Causes• Refraction- The bending of light rays as they
pass through the structures of the eye• Myopia- Nearsightedness• Hyperopia- Farsightedness• Astigmatism- Blurred vision caused by an
irregular cornea or lens• Glaucoma- A condition of excessive pressure in
the eyeball; cause is unknown; if untreated, blindness results
• Cataracts- Condition caused by clouding of the lenses of the eye; affects color vision and distance
![Page 10: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/10.jpg)
Causes• Diabetic retinopathy- condition resulting from
interference with the blood supply to the retina• Retinitis pigmentosa- degeneration of the
retina; causes the field of vision to narrow and affects night vision
• Tunnel vision- problems in peripheral vision• Night blindness- problems in seeing at low
levels of illumination• Cortical visual impairment- childhood condition
that is characterized by large day-to-day variations in visual ability
![Page 11: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/11.jpg)
Causes
• Retinopathy of prematurity (ROP)- Abnormal growth of blood vessels in the eye; related to premature birth
• Strabismus- Eyes are directed inward or outward; cross eyes
• Nystagmus- Rapid involuntary movements of the eyes; can indicate a brain malfunction or inner ear problems
![Page 12: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/12.jpg)
Psychological and Behavioral Characteristics
• Language Development- the lack of vision does not have a very significant effect on the ability to understand and use language
• Intellectual Ability- there is no reason to believe that blindness results in lower intelligence
![Page 13: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/13.jpg)
Psychological & Behavioral Characteristics Cont.
• Orientation and Mobility skills- the ability to have a sense of where one is in relation to other people and objects in order to move in the environment
• Cognitive mapping- allows for better mobility• Academic achievement- direct comparisons of
the academic achievement of students who are blind with that of sighted students must be interpreted cautiously because the groups must be tested under different conditions
![Page 14: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/14.jpg)
Psychological and Behavioral Characteristics
• Social adjustment- social difficulties which may arise are more likely due to society’s inappropriate reaction to blindness
• Social skills may be difficult for people with visual impairments such as smiling; smiling is not as spontaneous a social response as it is for those who are sighted
![Page 15: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/15.jpg)
Psychological and Behavioral Characteristics
• Stereotypic behaviors- Any variety of repetitive behaviors that are sometimes found in individuals who are blind, severely retarded, or psychotic; also called blindisms
![Page 16: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/16.jpg)
Educational Considerations
• Braille– http://www.afb.org/braillebug/
• Use of Remaining Sight
• Listening skills
• Orientation and Mobility (O & M) Training
• Technological Aids
![Page 17: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/17.jpg)
Educational Placement Models• Intinerant teacher services- services for
students who are visually impaired in which the special education teacher visits several different schools to work with students and their general education teachers
• Residential placement- 7 percent of students with low vision loss between the ages of 6 and 21 are placed in a residential institution, wheras only about .5 percent of students with mental retardation are so placed
![Page 18: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/18.jpg)
Early Intervention
• Many infants who are blind lag behind their peers in motor development
• O & M training should be a critical component of preschool programming
• Many advocate that they should be placed in inclusive settings with sighted children; it is critical that teachers facilitate interactions between the children
• Extremely important for parents to be involved
![Page 19: Visual Disabilities](https://reader035.vdocument.in/reader035/viewer/2022062800/568142ae550346895daef020/html5/thumbnails/19.jpg)
Transition to Adulthood
• Many independent living skills need to be taught explicitly to those who are visually impaired
• Many working-age adults with visual impairments are unemployed, and those who do work are often overqualified for the jobs they hold
• The employment rate for adults aged 21 to 64 who have severe visual limitations was only 26%