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Lecture 11: Children with vision impairments
•What is the assessment for visual acuity?
•ability to clearly distinguish forms or discriminate details at a specified distance
•What is 20/20 vision?
•can see what a normally seeing eye sees at 20 ft.
•Visual impairments has two subtypes what are they?
•What is blindness defined as?
•as an acuity measure of 20/200 or less in the better eye with correction, or visual
acuity of more than 20/200 if the widest diameter of the field of vision subtends
an angle no greater than 20 degrees.
•What is low vision?
•(partially sighted) individuals are those with a visual acuity greater than 20/200
but not greater than 20/70 in the better eye, after correction
•What is the classification by Age of Onset?
•Congenital low vision refers to conditions that are diagnosable at birth or shortly
•Adventitious low vision refers to conditions caused by accident or disease some
time after birth.
•What is the prevalence ?
•1 in 1000 in children under the age of 18
•0.5% of all school-age children with disabilities
•What is the prevalence in school age population?
•75-80% of visually impaired have low vision
•What are the 4 types and causes?
•hyperopia ( farsightedness)
•presbyopia (sight of age)
•What are the types and causes, oculomotor problems?
•strabismus ( crossed eyed)
•Amblyopi ( lazy eye blindness)
•What is the damage to the retina?
•retinitis pigmentosa: gradual degeneration of the retina
•What is ushers syndrome?
•combination of congenital deafness and retinitis pigmentosa
•What is retinopathy of prematurity (ROP)?
•abnormal growth of blood vessels in the eye
•What is diabetic retinopathy?
•a disease of the retina’s blood vessels
•What is macular degeneration?
•gradual deterioration of central area of the retina
•maintain peripheral vision but central vision impaired
• What is another cause of visual impairment?