AER/DENVER - JULY, 2000
CORTICAL VISUAL IMPAIRMENT (CVI)
Cortical Visual Impairment (CVI) is a disability resulting from either an insult to the brain or how the brain organization became configured during prenatal development. CVI effects how an individual understands the visual information received by the eyes. The location and extent of the brain insult determines which functional behaviors will be effected. For those who show some visual responses during infancy, the prognosis for increased functional use of vision is good. Indeed, many (not all) may use vision as their primary information gathering sensory modality when they are older.
Commonly Known General Characteristics of CVI Include
- Wide variations in functional use of vision: Some individuals demonstrate no visual responses at any times while other individuals have considerable use of vision
- Wide variability in an individual's ability to efficiently use vision on a consistent basis.
- Wide variation in regard to additional disabilities which may/may not include other ocular handicaps, medical and health problems, seizures, hearing, communication, self care skills, feeding, cognition, type of visual and auditory stimuli understood, interpersonal relationships, learning, etc.
- Wide variability within individual persons and between individuals in managing multi-sensory demands and planning/implementing motor responses
- Tendency to use peripheral vision more than central vision
- Possible depth perception difficulties
- Tendency to look away when reaching
- Tendency to have associated central auditory processing problems
- may be very interested in sounds
- may give the appearance of understanding all they hear
- may be particularly responsive to intonations rather than actual words
Characteristics of CVI Not Commonly Addressed
Some individuals with CVI do not have obvious additional disabilities. These individuals may be able to walk, care for themselves, talk, and have excellent visual behaviors for some types of stimuli. However, they may have visually-based difficulties with specific stimuli and skills that are of neurological origin. These individuals may have difficulty or the inability
- to recognize objects in general or specific categories of objects - especially stationary objects
- to recognize and discriminate one human face from another (Remember: All faces have eyes, ears, nose & mouth and, thus, are structurally the same.)
- to recognize a human face as more than an object unless it moves or talks.
- to organize oneself spatially
- to comfortably move through even a very familiar environment
- to recognize and use visual symbols which may include print, photographs and/or line drawings
- to recognize colors
- to point to various parts of their own body
- to distinguish left from right.
Prosopagnosia and Facial Agnosia
A particular sub-set of individuals with CVI may have difficulty or the inability to recognize familiar faces (Prosopagnosia) or difficulty or inability to recognize any face, familiar or not (Facial Agnosia). Processing the human face is an extraordinarily complex visual,neurological, social, and communicative process. These individuals may have several of the following characteristics:
- May have different neurological sources causing the condition.
- May have variations between persons in brain imaging results.
- Will show variations even within this sub-group of persons with CVI. For example, may/may not have associated agnosias (not recognize objects and/or certain categories of objects and/or two dimensional visual representations and/or certain categories of two dimensional visual representations).
- May avoid visually fixating on the human face OR
- May stare intently at the human face OR
- May look toward only one part of the face (i.e., mouth) rather than the facial configuration
- May be able to name and/or point to various parts of the face but not recognize and identify the total configuration.
- May recognize some faces from one orientation, within context, but not be able to generalize that face to other orientations or situations.
- May want to touch people - especially their faces
- May not realize that they differ from others in recognizing faces
- May not understand totality of language but brighten considerably when language is combined with emphasized intonation.
- May understand language but have difficulty in using pronouns
- May use language but tend, at times, to "talk to the air"
- May have difficulty in discriminating one voice from another
- May have excellent short term auditory memory
- May not realize a person is present unless the person says something or moves
- May focus on a specific aspect of a person for identification (if they realize person is present)
- May treat people as objects
- May have difficulty relating to peers
- May appear to prefer objects to people
- May have "subtle" additional disabilities such as fine and gross motor dyspraxia, social interactions, pragmatics of language, behavior, spatial disorganization
- May show definite ability to learn - especially colors, shapes, repeating alphabet, etc.
- May/may not have difficulty interpreting some/all types of two dimensional visual representation (very variable)
- Some may be able to recognize pictorial representations of faces but not be able to do so with tangible face
- May have difficulty managing multiple sensory-motor demands - frequently said to have sensory integration problems
- May have difficulty modulating their states of arousal.
- Frequently said to be inattentive and distractible - sometimes labeled ADHD, PDD, autistic
- Perceptual impairments usually are an insufficient explanation for face-specific agnosia
- For many of the children, however, vision is their primary information gathering sensory modality
- Individuals who have the condition from birth may function better with the condition than those adults who suddenly acquire the condition due to some insult.
Some Diagnostic Strategies
- What is the visual diagnosis?
- What is the cause (etiology) of the condition?
- Have any types of brain imaging procedures been done?
- Parent reporting
- School reporting
- Systematic Observations
An Initial Reading List To Begin The Process of Understanding
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Bruce, V. & Humphreys, G. (1997). Object and face recognition. Journal Visual Cognition - Special Issue. England: Taylor & Francis Publishers.
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Dutton, G., Day, R. & McCulloch, D. (1999). Who is a visually impaired child? A model is needed to address this question for children with cerebral visual impairment. Developmental Medicine & Child Neurology, 41, 211-213.
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