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Versión Español de este artículo (Spanish Version)
Reprinted with permission from Blind Babies Foundation
Cortical Visual Impairment (CVI) is a temporary or permanent visual impairment caused by the disturbance of the posterior visual pathways and/or the occipital lobes of the brain. The degree of vision impairment can range from severe visual impairment to total blindness. The degree of neurological damage and visual impairment depends upon the time of onset, as well as the location and intensity of the insult. It is a condition that indicates that the visual systems of the brain do not consistently understand or interpret what the eyes see. The presence of CVI is not an indicator of the child's cognitive ability.
The major causes of CVI are asphyxia, perinatal hypoxia ischemia ("hypoxia": a lack of sufficient oxygen in the body cells or blood; "ischemia": not enough blood supply to the brain), developmental brain defects, head injury, hydrocephalus, and infections of the central nervous system, such as meningitis, and encephalitis.
Initially, children with CVI appear blind. However, vision tends to improve. Therefore, Cortical Visual Impairment is a more appropriate term than Cortical Blindness. A great number of neurological disorders can cause CVI, and CVI often coexists with ocular visual loss, so the child should be seen by both a pediatric neurologist and a pediatric ophthalmologist.
The diagnosis of Cortical Visual Impairment is a difficult diagnosis to make. It is diagnosed when a child has poor or no visual response and yet has normal pupillary reactions and a normal eye examination. The child's eye movements are most often normal. The visual functioning will be variable.
The result of an MRI (Magnetic Resonance Imaging) in combination with an evaluation of how the child is functioning visually, provide the basis for diagnosis.
Children with CVI have different abilities and needs. The presence of and type of additional handicaps vary. Some children have good language skills and others do not. Spatial confusion is common in children with CVI because of the closeness of the occipital and parietal lobes of the brain.
Habilitation should be carefully planned.
A full evaluation by a number of professionals is essential. The evaluation team could include: teachers (of the visually impaired or severely handicapped), physical therapists (PTs), occupational therapists (OTs), speech therapists, and orientation and mobility specialists.
The following statements are not true, according to current knowledge in the field:
"When a child with CVI needs to control his head, use his vision, and perform fine motor tasks, the effort can be compared to a neurologically intact adult learning to knit while walking a tightrope."
1. "Observations on the Habilitation of Children with Cortical Visual Impairment" Groenveld, M.; Jan, J.E.; Leader, P., Journal of Visual Impairment and Blindness, January, 1990.
2. "Visual Behaviors and Adaptations Associated with Cortical and Ocular Impairment in Children," Jan, J.E.; Groenveld, M; Journal of Visual Impairment and Blindness, April 1993, American Foundation for the Blind.
3. Video: "Issues in Pediatric Ophthalmology: Cortical Visual Impairment (1994)," Child Health and Developmental Media, Inc., 5632 Van Nuys Blvd., Suite 286, Van Nuys, CA 91401.
4. "Cortical Visual Impairment in Children," Good, W.; Jan, J.E.; Luis, D. (1994) Surveys of Ophthalmology. 38:4: 351-364.
Julie Bernas-Pierce, Editor
Dr. Creig Hoyt
Dr. William Good
Off to a Good Start Program
The Pediatric Visual Diagnosis Fact Sheets are sponsored by the Blind Childrens Center and the Hilton/Perkins Program through a grant from the Conrad Hilton Foundation.
Blind Babies Foundation
1200 Gough Street
San Francisco, California 94109
NOTE: Blind Babies Foundation has developed 7 Pediatric Visual Diagnosis Fact SheetsTM on the following topics: Cortical Visual Impairment, Retinopathy of Prematurity, Optic Nerve Hypoplasia, Albinism, Optic Atrophy, Retinal Diseases, and Vision Assessment. One complete set costs $10. Families can get one Fact Sheet free of charge upon request. The Blind Children's Center will soon have the Fact Sheets available on their website at <www.blindcntr.org/bbc>.
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Go to Fall 1998 Table of Contents.