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CVI – Background and Assessment Part 1

CVI – Background and Assessment Part 1. Heather Brooks, Educational Consultant North Carolina Department of Public Instruction. Today we’ll be discussing. Today we’ll be discussing.... Brains & Eye Balls. Vision.

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CVI – Background and Assessment Part 1

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  1. CVI – Background and Assessment Part 1 Heather Brooks, Educational Consultant North Carolina Department of Public Instruction

  2. Today we’ll be discussing Today we’ll be discussing.... Brains & Eye Balls

  3. Vision Example: You’re walking along in the park and you see these three bears. Eye Brain Processing Movement

  4. Brain Thinking About Grizzly Bears

  5. Motor Action Taken After Seeing a Grizzly

  6. Quick Review of the Eye:I know you know this Video: How the Eye Works and the Retina https://www.youtube.com/watch?v=Sqr6LKIR2b8

  7. Brain Structure Vision is not simply processed in the visual cortex. There are numerous places in the brain responsible for interpretation and reaction to visual stimulus.

  8. Cortical Visual Impairment • CVI occurs due to damage in the brain. • So let’s talk about brain damage for a minute.

  9. What’s the Cortex? Cerebral Cortex Cerebrum

  10. Brain Damage The human brain… Has a limited ability to store glucose or oxygen. It is also encompassed in a hard shell (skull) that doesn’t allow for much swelling.

  11. Brain Damage – Oxygen, Glucose, & Waste Management Blood brings with it fresh oxygen and glucose. Blood takes away the waste that builds up in the cells. Without fresh, oxygen rich blood…. cell death occurs.

  12. Brain Damage – 2 Important Terms • Ischemia – lack of blood supply • Hypoxia – lack of oxygen The most common cause Of cvi is hypoxic-ischemic Injury.

  13. Examples: Brain Damage Shunt Failure Infections Metabolic Disease Drugs Microbes Stroke Trauma Complications of Cardiac treatment…

  14. Neuralplasticity: Finding a New Path • The brain can learn to reroute information/find new neural pathways • Visual recovery is better for younger children Neurological Insult in Children • Neurological improvement happens for two or more years after the injury • Children recover better in the immediate time frame and improve for longer periods *Important that we not set limits or have a predetermined idea of what a child can learn or how far a child can progress.*

  15. Just to lighten it up for a moment.

  16. What is CVI? • Cortical Visual Impairment • No single definition for CVI • Generally speaking, CVI is vision loss due to damage in the brain • CVI can manifest in different ways, with a wide range of severity. Mild Severe Profound Functional Blindness Idiosyncratic Impact on Vision

  17. How is CVI diagnosed? • Clinical diagnosis – no specific medical test for CVI • Normal eye exam – or the eye disorder does not explain the visual behavior • History of neurological insult • Demonstrate unique visual and behavior characteristics associated with CVI

  18. Examples of Unique Visual and Behavior Characteristics • Slow, inefficient, and highly variable visual performance • Light gazing/Photophobia paradox • Color vision and perception of movement is often preserved • Look Look Away Reach • Visual Agnosias (inability to recognize)

  19. Prevalence of CVI Leading cause of pediatric visual impairment in the developed world. Because…

  20. Comorbid Conditions • Epilepsy • Cerebral palsy • Intellectual disabilities • Hearing loss • Hydrocephalus • Abnormal mental development • Microcephaly • Progressive degenerative disorders • Hypotonia

  21. Lots of Names with Visual Impairment Involving the Brain Cortical Visual Impairment Cerebral Visual Impairment Neurological Visual Impairment Delayed Visual Maturation Cortical Blindness Cortical Visual Dysfunction

  22. CVI Perspectives • Gordon Dutton – Medical • Lea Hyvärinen – Medical with strong emphasis on optics • Roman-Lantzy – Educational

  23. Gordon Dutton, MD • Lower Level CVI • Damage to the visual pathway at the striate cortex • Results in damage to visual acuity, understanding of what is being seen, and visual fields may be impacted • Higher Level CVI • Damage occurring beyond the striate cortex • Specific functional loss of vision (e.g., movement, shape, or color) • Both

  24. Visual stimulus is processed in lots of places in the brain Vision-for-Action Vision-for-Perception

  25. Dutton Theory Continued Dorsal Stream Vision-for-Action Ventral Stream Vision-for-Perception Dysfunction in this area: Prosopagnosia Difficulty understanding facial expressions Route finding problems Various visual agnosias (inability to visually identify objects) Dysfunction in this area: • Difficulty complex visual scenes • Issues moving through space • Trouble finding an object/person from within a group • Inaccurate visual reaching • Decreased lower field • Frustration

  26. Visual Agnosia Video: My Strange Brain https://www.youtube.com/watch?v=kuKqi93FMgQ

  27. Test Your Facial Recognition Skills Lighten things up 2. 1. 4. 3.

  28. Lea Hyvärinen, MDFinnish Pediatric Ophthalmologist • Dorsal, Ventral, and…. Mirror Neurons • Mirror neurons are activated when watching others • Important in visual communication • Foundation for imitation of expressions and thus emotional bonding

  29. Additional Medical Views of CVI: Lea Hyvärinen, MD • Scotoma: Blind spot in the visual field • Scotomas and CVI: • Central scotomas “very common in children with CVI” • If the child is looking away to look at something, eccentric fixation may be what they’re using

  30. Additional Medical Views of CVI: Lea Hyvärinen, MD • Saccade: fast movements of the eye that are present in normal visual functioning and important in visual tasks like reading • Saccade and CVI: • slower than normal • inexact in landing at target • or there may be no fast eye movements at all

  31. Lea Symbols: Lea Hyvärinen, MD Optotypes - symbols used to determine visual acuity for prereaders or students with other disabilities

  32. Lea Hyvärinen Cont. Video: Baby Eyes: A Vision Test for Tots https://www.youtube.com/watch?v=3JcAsXuy7ac

  33. Christine Roman-Lantzy, Ph.D Part 1 APH “CVI Perspectives”

  34. Christine Roman-Lantzy, Ph.D • Color Preference • Need for movement • Visual latency • Visual Field preferences • Decreased visual complexity • Light-gazing & non-purposeful gaze • Decreased distance vision • Atypical visual reflexes • Decreased visual novelty • Decreased visually guided reach

  35. Homework Identify 3 online or hard copy articles pertaining to CVI. Write a summary of the findings for one of the articles.

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