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Cortical Visual Impairment

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Presentation on theme: "Cortical Visual Impairment"— Presentation transcript:

1 Cortical Visual Impairment
Children with CVI are those in whom visual dysfunction is caused by lesions in the posterior visual pathways and or occipital lobes and results in temporary or permanent loss of vision. From APH website: Definition for Medical Purposes: Cortical visual impairment (CVI) may be defined as bilaterally diminished visual acuity caused by damage to the occipital lobes and or to the geniculostriate visual pathway. CVI is almost invariably associated with an inefficient, disturbed visual sense because of the widespread brain disturbance. See brain diagrams. Definition for Educational Purposes: Cortical visual impairment (CVI) is a neurological disorder, which results in unique visual responses to people, educational materials, and to the environment. When students with these visual/behavioral characteristics are shown to have loss of acuity or judged by their performance to be visually impaired, they are considered to have CVI. Note: A student whose visual functioning is reduced by a brain injury or dysfunction may be considered blind for educational purposes if visual function is equal to or less than the legal definition of ocular blindness.

2 Common Etiologies Prenatal Perinatal Acquired
Toxemia, intrauterine infection Perinatal Asphyxia, meningitis, encephalitis Acquired Tumor, trauma, cardiac arrest, seizures, shunt malfunction

3 Diagnostic Criteria Pupillary reaction is normal
Optic refractive media and fundus appear normal Blink to threat is absent Tracking behaviors usually absent

4 Characteristic Behaviors
Eye contact and visual communication skills are poor Often appear uninterested in surroundings May turn away from people and events in their environment Photophobia often coexists with light gazing Other identified behaviors are listed in the CVI protocol

5 Visual Functioning Distance vision is apparent, but children may bring objects in close to block out visual clutter and chaos Verbal and tactile cuing is helpful for some children, but may provide too much distraction for others Fluctuations in visual functioning Familiar objects recognized in one environment and not others Visual attention is highly variable Visually locates object then looks away before reaching for object Differences in visual functioning may be due to differences in environment rather than in vision itself Every time you change the environment, you change the visual response Looking away before reaching behavior may indicate a need for child to process visual information before engaging in motor response Or child may be taking advantage of visual fields, or using one eye to spot something and the other eye to identify it Look to reach behavior may diminish as CVI is resolved Distance vision may seem to improve as complexity becomes less of an issue for a child Verbal and tactile cuing may be too much input for some children – try presenting materials without vocalizing for some children

6 Fluctuations in Visual Functioning
Visual functioning is influenced by: Tiredness Unfamiliar environments Illness Complex visual information Poor lighting Medications Seizures All of these things affect vision, complex visual information may have most impact Arrange optimal sensory environment when possible

7 Color vision is a strength for children with CVI
Visual Perception Color vision is a strength for children with CVI Colors are more easily recognizable than shapes Yellow and red seem to be the preferred colors

8 Visual Perception (con’t)
May only be able to attend to one object at a time Need sufficient distance between objects to distinguish them Attend better to objects in motion Discrimination of foreground from background is difficult Do not appear to see stationary objects but respond to moving objects, some children appear to see better when they are moving themselves

9 Resolution of CVI 25 to 50 percent of children with CVI recover some useful vision First three years of life are optimal time for resolution of CVI First two to three years after accident/trauma to the brain are optimal for recovery of vision However, resolution can occur into the teens and beyond! Resolution possible because of plasticity in the neurons of visual system – more plasticity in younger children

10 Assessment and Intervention Strategies
Use vestibular input to alert visual system Insure proper seating, support and alignment Avoid overwhelming the visual system with complex visual stimuli Allow time for observation, assimilation and response Assessment become the intervention Traditional methods of enriching the visual environment may be detrimental to students with CVI because as the amount of visual stimuli increases, the ability to process stimuli decreases (also true for the verbal and tactile cuing we mentioned earlier – too much information may be so chaotic and disturbing that the child avoids vision – if process tactile or auditory input is easier, he may react to those stimuli rather than use his or her vision

11 Additional Assessment and Intervention Strategies
Illuminated toys Toys with motion, or those that appear to have motion Single stimulus Colored objects and toys Highlight aspects of toys, objects, shapes, etc. with favorite colors Wide separation between array of objects Books with single picture on each page High contrast between foreground and background Familiar toys and objects Begin with single stimulus and then add others as CVI resolves Begin with familiar objects to elicit looking behavior then add variety

12 ISAVE CVI Protocol Complete the Developmental History and Ocular Examination sections of the CVI protocol after interviewing caregivers and reviewing referral information, developmental history, and medical records. Transfer observations from other ISAVE components to the CVI protocol, especially those from the Ecological Observations component. Stimuli for assessment include materials suggested for use throughout ISAVE – be cautious of toys that do too many things at once The information from the Ecological Observations protocol will be essential for CVI students since environment plays such an important role in visual functioning

13 CVI Protocol: Developmental History
Complete thorough interviews with caregivers and review of medical information Check all markers on the protocol that are relevant for the child. There are no pass or fail responses.

14 CVI Protocol: Ocular Examination
Gather information using reports from ophthalmologist or other eye care professional. Check all markers on the protocol that are relevant for the child.

15 CVI Protocol: Additional Areas
Appearance Visual Functioning, Visual Perceptual Characteristics Sensory Modalities Posture and Movement Characteristics In each of these areas, gather information through personal observation, interviews with caregivers and other professionals. Check all markers on each protocol relevant to the child.

16 CVI Protocol: Impressions and Recommendations
Indicate your impressions and recommendations for further services and additional referrals.

17 Transfer results from the CVI component to the ISAVE Summary Protocol.
Familiarity with diagnostic criteria and behavioral characterisitcs associated with CVI will help teachers, parents, eye-care professionals, therapists and others to work together as a team to remediate and resolve CVI.

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