Presentation on theme: "Cortical Visual Impairment"— Presentation transcript:
1Cortical 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.
3Diagnostic Criteria Pupillary reaction is normal Optic refractive media and fundus appear normalBlink to threat is absentTracking behaviors usually absent
4Characteristic Behaviors Eye contact and visual communication skills are poorOften appear uninterested in surroundingsMay turn away from people and events in their environmentPhotophobia often coexists with light gazingOther identified behaviors are listed in the CVI protocol
5Visual FunctioningDistance vision is apparent, but children may bring objects in close to block out visual clutter and chaosVerbal and tactile cuing is helpful for some children, but may provide too much distraction for othersFluctuations in visual functioningFamiliar objects recognized in one environment and not othersVisual attention is highly variableVisually locates object then looks away before reaching for objectDifferences in visual functioning may be due to differences in environment rather than in vision itselfEvery time you change the environment, you change the visual responseLooking away before reaching behavior may indicate a need for child to process visual information before engaging in motor responseOr child may be taking advantage of visual fields, or using one eye to spot something and the other eye to identify itLook to reach behavior may diminish as CVI is resolvedDistance vision may seem to improve as complexity becomes less of an issue for a childVerbal and tactile cuing may be too much input for some children – try presenting materials without vocalizing for some children
6Fluctuations in Visual Functioning Visual functioning is influenced by:TirednessUnfamiliar environmentsIllnessComplex visual informationPoor lightingMedicationsSeizuresAll of these things affect vision, complex visual information may have most impactArrange optimal sensory environment when possible
7Color vision is a strength for children with CVI Visual PerceptionColor vision is a strength for children with CVIColors are more easily recognizable than shapesYellow and red seem to be the preferred colors
8Visual Perception (con’t) May only be able to attend to one object at a timeNeed sufficient distance between objects to distinguish themAttend better to objects in motionDiscrimination of foreground from background is difficultDo not appear to see stationary objects but respond to moving objects, some children appear to see better when they are moving themselves
9Resolution of CVI25 to 50 percent of children with CVI recover some useful visionFirst three years of life are optimal time for resolution of CVIFirst two to three years after accident/trauma to the brain are optimal for recovery of visionHowever, resolution can occur into the teens and beyond!Resolution possible because of plasticity in the neurons of visual system – more plasticity in younger children
10Assessment and Intervention Strategies Use vestibular input to alert visual systemInsure proper seating, support and alignmentAvoid overwhelming the visual system with complex visual stimuliAllow time for observation, assimilation and responseAssessment become the interventionTraditional 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
11Additional Assessment and Intervention Strategies Illuminated toysToys with motion, or those that appear to have motionSingle stimulusColored objects and toysHighlight aspects of toys, objects, shapes, etc. with favorite colorsWide separation between array of objectsBooks with single picture on each pageHigh contrast between foreground and backgroundFamiliar toys and objectsBeginwith single stimulus and then add others as CVI resolvesBegin with familiar objects to elicit looking behavior then add variety
12ISAVE CVI ProtocolComplete 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 onceThe information from the Ecological Observations protocol will be essential for CVI students since environment plays such an important role in visual functioning
13CVI Protocol: Developmental History Complete thorough interviews with caregivers and review of medical informationCheck all markers on the protocol that are relevant for the child.There are no pass or fail responses.
14CVI 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.
15CVI Protocol: Additional Areas AppearanceVisual Functioning,Visual Perceptual CharacteristicsSensory ModalitiesPosture andMovement CharacteristicsIn 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.
16CVI Protocol: Impressions and Recommendations Indicate your impressions and recommendations for further services and additional referrals.
17Transfer 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.