Jason sits on the floor at a low table. His head is cocked, his eyes looking up at the ceiling. There is a pegboard in front of him. He fits a red peg in, then a yellow. He stacks a second red one into the first, the blue peg he picks up next gets its own slot. When shown a series of headshots, Jason has trouble recognizing one person from another.
Cortical Visual Impairment, is also known as Cerebral Visual impairment, or CVI. It is a visual impairment that is caused by damage or abnormalities in either the posterior visual pathways or the occipital lobes in the brain. Most people with CVI have normally functioning eyes. CVI is most often found in children, and in many cases is not permanent. In young children it is caused by trauma either in utero or after birth. CVI can be difficult to diagnose, many of the characteristics do not seem directly related to vision.
Lack of enough oxygen in the blood, or blood to the brain.
Infection in the central nervous system such as Meningitis.
Brain damage due to trauma.
Children with CVI can often see to some extent, some have peripheral vision but not central, others can see light but not gauge shapes or depth. Many children with CVI have fluctuating visual signals. They may see better at some times than others.
The unstable visual signals in a young child with CVI can result in delayed walking, more difficulty mastering simple tasks (especially ones learned through imitation, or visually demanding such as reading and writing).
A child with CVI rarely make eye contact: his eyes may wander, or she may look out of the corner of her eyes.
One child with CVI may be hyper sensitive to light, while another is attracted to light.
Sometimes vision improves with motion, and a child with CVI will seem captivated by moving objects, or be in constant motion his or herself.
Depth perception, and spatial orientation are often poor.
The key to successfully working with a child with CVI is learning the needs of that specific child. As there are some common characteristics, however, the following strategies that can be used in most cases.
Remember that the child's vision fluctuates, if he seems unable to successfully complete a task he was able to do on a prior day, be persistant but patient, he may not be able to see as well currently.
Use pictures that are simple. The child may not be able to differentiate between foreground and background on a two-dimentional image. So simple images on a single-colored background work best.
Use contrasting colors. Most children with CVI can see colors, but two shades of green may be harder to decipher than green white, for example.
Incorporate physical skills. While a child with CVI may be able to navigate a room without bumping into things1, they will likely have difficulty with depth perception and balance.
Use a combination of verbal instructions and physical example. A child with CVI may respond better if a task is associated with a verbal cue.
Repitition, repitition! Be persistent, work on a single task and repeat it. Have the child repeat it. Try to do it in the same manner, with the same accompanying verbal cues each time.
Watch the child for signals of fatigue. It takes a great deal of effort for the child to focus on visually demanding tasks. Allow for breaks when the child begins to tire.
CVI is a relatively new diagnosis. There is still a great deal to be learned about its causes, characteristics, and long-term effects. Because CVI is so difficult to diagnose, it is recommended that a full team of professionals participtate in the assessment process. CVI can be accompanied by other brain abnormalities, or physical handicaps and therefore the diagnosis process should include people from the fields of special education, physical and occupational therapy as well as speach and mobility specialists. While this may seem like a formidable number of people, especially for a young child it is critcal. Between birth and five years old a child masters a greater number of physical and mental skills that they will in any other five year period. The sooner the obstacles to this process can be accurately diagnosed, the sooner the parents and specialists can start working to address the child's specific needs.
1blind sight is a function of a visual system in the brain stem, seperate from the posterior visual pathways and occipital lobes.
Citations: "Pediatric Visual Diagnosis Fact Sheet" Blind Babies Foundation. accessed April 5, 2003.
"Autistic Spectrum Disorders and Crtical Visual Impairment:
Two Worlds on Parallel Courses" accessed April 5, 2003.
“Cortical Visual Impairment Pediatric Visual Diagnosis Fact Sheet” SESA - Spring 2000 Reference Shelf -Cortical Visual Impairment. accessed April 5, 2003.
Opening anecdote witnessed by author. Child was three-year-old male working with special education teacher. Names have been changed.