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SPED 537 ECSE Methods Multiple Disabilities Chapter 4

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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  1. SPED 537 ECSE Methods Multiple DisabilitiesChapter 4 March 13-14, 2006 Deborah Chen, Ph.D. CSU, Northridge

  2. 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

  3. Definitions • Legally blind • Totally blind • Light perception • Form perception • Partially sighted • Low vision

  4. Types of Visual Impairment • Decreased visual acuity • Field loss • Loss of contrast sensitivity • Color blindness • Ocular-motor problems • Cortical visual impairment • Delayed visual maturation

  5. Causes of Acuity Loss • Retinopathy of Prematurity • Cataracts • Nystagmus • Refractive errors • Strabismus

  6. Refractive Errors • Myopia • Hyperopia • Astigmatism

  7. Strabismus • Esotropia • Exotropia • Hypertropia • Hypotropia

  8. Clinical Vision Tests: Fixationand Eye Alignment • Versions • Hirshberg • Krimsky • Unilateral and alternating cover test • Base-out prism

  9. Clinical Vision Tests • Pupillary response • Vestibular ocular reflex (VOR)- similar to Optokinetic Nystagmus (OKN) test • Refractive Error

  10. Behavioral Tests • Contrast sensitivity • Color vision • Depth perception • Visual fields • Visual acuity (Teller Cards)

  11. Electrophysiological Tests • Visual Evoked Potential (VEP) or Visual Evoked Response (VER) • Electroretinography (ERG)

  12. Checking for Ocular Health Examines the front and back structures, retinal, optic nerve

  13. Ocular Visual Impairment • Atypical eye exam • Consistent visual attention • Nystagmus • Restrictions of visual fields • Occasional photophobia • Eye pressing • Occasional head shaking • Light gazing

  14. 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)

  15. Visual Responses Awareness Attention Understanding Fixation Tracking Peripheral Central Simple Complex

  16. Visual Responses Awareness Attention Understanding Large Small Familiar Unfamiliar Near Far

  17. Visual Stimuli • Preferred: • Objects with lights or movement • Geometric designs • High contrast materials • Bright colors • Familiar: • Family members • Clothing, utensils, household items • Toys • Pictures

  18. 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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