Sped 537 ecse methods multiple disabilities chapter 4
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SPED 537 ECSE Methods Multiple Disabilities Chapter 4. March 13-14, 2006 Deborah Chen, Ph.D. CSU, Northridge. Incidence of Visual Impairments. 1 in 3000 children 46% congenital 38% vision loss in 1 st year of life 25 % totally blind 25 % light perception 50% functional vision.

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SPED 537 ECSE Methods Multiple Disabilities Chapter 4

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Sped 537 ecse methods multiple disabilities chapter 4

SPED 537 ECSE Methods Multiple DisabilitiesChapter 4

March 13-14, 2006

Deborah Chen, Ph.D.

CSU, Northridge


Incidence of visual impairments

Incidence of Visual Impairments

  • 1 in 3000 children

  • 46% congenital

  • 38% vision loss in 1st year of life

  • 25 % totally blind

  • 25 % light perception

  • 50% functional vision


Definitions

Definitions

  • Legally blind

  • Totally blind

  • Light perception

  • Form perception

  • Partially sighted

  • Low vision


Types of visual impairment

Types of Visual Impairment

  • Decreased visual acuity

  • Field loss

  • Loss of contrast sensitivity

  • Color blindness

  • Ocular-motor problems

  • Cortical visual impairment

  • Delayed visual maturation


Causes of acuity loss

Causes of Acuity Loss

  • Retinopathy of Prematurity

  • Cataracts

  • Nystagmus

  • Refractive errors

  • Strabismus


Refractive errors

Refractive Errors

  • Myopia

  • Hyperopia

  • Astigmatism


Strabismus

Strabismus

  • Esotropia

  • Exotropia

  • Hypertropia

  • Hypotropia


Clinical vision tests fixation and eye alignment

Clinical Vision Tests: Fixationand Eye Alignment

  • Versions

  • Hirshberg

  • Krimsky

  • Unilateral and alternating cover test

  • Base-out prism


Clinical vision tests

Clinical Vision Tests

  • Pupillary response

  • Vestibular ocular reflex (VOR)- similar to Optokinetic Nystagmus (OKN) test

  • Refractive Error


Behavioral tests

Behavioral Tests

  • Contrast sensitivity

  • Color vision

  • Depth perception

  • Visual fields

  • Visual acuity (Teller Cards)


Electrophysiological tests

Electrophysiological Tests

  • Visual Evoked Potential (VEP) or Visual Evoked Response (VER)

  • Electroretinography (ERG)


Checking for ocular health

Checking for Ocular Health

Examines the front and back structures, retinal, optic nerve


Ocular visual impairment

Ocular Visual Impairment

  • Atypical eye exam

  • Consistent visual attention

  • Nystagmus

  • Restrictions of visual fields

  • Occasional photophobia

  • Eye pressing

  • Occasional head shaking

  • Light gazing


Cortical visual impairment

Cortical Visual Impairment

  • Normal eye exam

  • Variable vision

  • Short visual attention

  • No nystagmus

  • No head shaking

  • No eye pressing

  • Light gazing

  • Photophobia in 1/3 cases

    ( Dr. J. Jan, Children’s Hospital, Vancouver, B.C. Canada)


Visual responses

Visual Responses

Awareness Attention Understanding

Fixation Tracking

Peripheral Central

Simple Complex


Visual responses1

Visual Responses

Awareness Attention Understanding

Large Small

Familiar Unfamiliar

Near Far


Visual stimuli

Visual Stimuli

  • Preferred:

    • Objects with lights or movement

    • Geometric designs

    • High contrast materials

    • Bright colors

  • Familiar:

    • Family members

    • Clothing, utensils, household items

    • Toys

    • Pictures


Visual saliency

Visual Saliency

  • Motivation factors

  • Lighting (natural, indoor, outdoor, dark)

  • Position (placement of target)

  • Distance from child

  • Highlight or contrast

  • Illumination of target

  • Characteristics of target


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