Cortical Visual Impairment - A Challenging Diagnosis
Originally appeared in Children's Vision Concerns: Looks Beyond the Eyes
This chapter has been done in response to the need for understanding and respect for the Cortically Visually Impaired (CVI) children's perspective. Since they generally seem to "see," it is easy to overlook cognitive implications related to the seriousness of the influence of CVI on processing visual messages. Too often, I have gone into programs where children with obvious CVI do not have their visual challenges incorporated into their profile. My heart is heavy when I recognize that their intervention parallels that of sighted peers, yet their ability to process is different, without benefit of this primary organizing sense. Families, too, deserve to understand the diagnosis, so that they can learn to cue their child in ways that will help promote purposeful involvement with their world, whether it means lifting a finger to touch an object, or developing tools for real independence.
Cortical Visual Impairment
The diagnosis of Cortical Visual Impairment or Insufficiency (CVI) is difficult to understand, although it is a leading cause of vision problems in children. Part of the challenge is that it reflects problems in the processing part of the visual system which are often difficult to define. In addition, many children with CVI don't "look" visually impaired, so the condition may go unaddressed for quite some time, especially if there are other medical issues that are a major focus.
How is the diagnosis of CVI made?
With Cortical Visual Impairment, the eyes, which gather the visual information, generally "look good", with the pupils responding and no sign of disease. The optic nerves may also appear normal, indicating that messages can be transmitted from the eyes to the occipital cortex (vision related part of the brain). Yet, the child does not appear to be "visually sparked" or motivated to use vision to scan for details.
Of primary importance is the child's history. Was the gestation normal? Was there birth trauma? Did the child stop breathing? Is there a history of hydrocephalus, cysts or brain malformations? Was there other illness including high fever, meningitis, or a metabolic disorder? Was there an accident or insult to the head? Near drowning? Anything that could have altered the brain's transmission of impulses related to processing and sifting visual messages may contribute to the diagnosis.
- An ERG (Electroretinogram) may be requested to rule out retinal problems.
- A VEP (Visual Evoked Potential) gives some brain reception information related to vision, but is not conclusive due to variability.
- Brain scans and neuro-imaging are of value in determining the cause of some symptoms and to rule out some concerns.
- Behavioral characteristics of apparent visual function of CVI children also contribute significantly to the diagnosis.
What are characteristics of CVI and what does it mean?
- Functional use of vision is obviously affected. It has been described as being similar to holding several (11 or 12) layers of crinkled Saran Wrap in front of your eyes. As you look around, remember that you are piecing the information together with a visual memory and experiential foundation that the child has not yet acquired.
- Sometimes CVI improves. Vision is both physiological and learned. Both aspects contribute to the changes with CVI that may occur for up to 6 years of life. The cause of the impairment and age of the child (younger) may influence the chances of apparent physical improvement. Cognitively, familiarity through interaction with people, objects and the environment may motivate the child to learn to look and piece together the unclear or fragmented visual information. A caution is to avoid false hope by not confusing improvement with cure.
- Visual alertness may appear to fluctuate. Sometimes the child seems to "see" better than other times.
- Many CVI children are attracted to lights ... especially fluorescent lights. They may turn to lights and stare. It is beneficial to occasionally draw the attention outward for more purposeful involvement.
- Conversely, some children may be light sensitive. Either way, lighting may be a consideration in maximizing useful vision.
- Many CVI children are attracted to look after an object has touched them. It is as though "touch-look" brings the visual experience personally into their space.
- Some CVI children tend to look away from a target as they are reaching for it. This may be an adaptation for visual field or use of peripheral vision to "look". In addition, once the object has been visually located, some multi-handicapped children with motor problems may turn away to concentrate on their grasping since the unclear visual component also requires concentration and looking, therefore, does not reinforce for the effort.
- Movement may catch the visual attention.
- Many CVI children have good travel vision. The brain seems to use undefinable input for safe mobility. This can be built upon for "active" rather than "passive" learning and motor knowledge to promote independence.
- When a CVI child can visually fix on an object and follow it, the tracking is often described as having saccadic or jerking movement. The visual pursuit may be more successful when the target is moved slowly. Further, if the child is expected to "look" at a picture for details, there is a risk that the jerky scanning may "catch" significant lines and "skip over" other parts. Thus, with computer work, for example, is the child responding to the picture detail, the movement, the color or the sound? Is there a real association with the pictures and purpose from the child's perspective?
- Many CVI children mouth objects. They may be picking up detail information with their mouth, thereby confirming blurred visual messages. Help the child refine tactual exploration to reinforce visual information.
- Purposeful handling of objects is valuable in developing an associative foundation for language. The child may even "look" for the object by label once the connection has been physically tied together.
- Simple, high contrast visual targets, with plain backgrounds, are easier to locate and process than "busy" targets.
- Spacing of objects is important in that "cluttering" or closeness may blend the objects of perception. Up to 3 or 4 inches of separation may be helpful, depending on size and contrast.
- The child may respond to basic colors rather than black and white visual targets. In fact, some CVI children can match and identify some colors.
- Often, CVI children do not have nystagmus, or involuntary rhythmic movement of the eyes. If there are other problems with the visual system that would usually be accompanied by nystagmus, sometimes the CVI may override the symptom. Know the total diagnosis. Consistent eye movement may be a result of medications.
What can be done?
All CVI children deserve to have input from the perspective of being seriously visually impaired. This means that with vision, the primary integrating sense, not giving clear incidental information, the child must learn to accommodate. Any activities that will help tie the world together and build on the innate curiosity to discover consistencies, the foundation for learning, will make a difference:
- Do individualized assessments of the CVI child, in several settings, and at varying times so that any unique behavioral characteristics will be understood and accepted as part of the profile to respect in helping and expecting the child to learn.
- "Hands on" processing with cueing for awareness of patterns and sequences of experiences, that will actively help the child become a part of the action, is a must. In effect, guide the child through the process to provide integrated information about how, what, where and why, from an inner perspective. Keep in mind that the child may be focusing on what your hands and movements are doing rather than the task until the experience becomes personally applicable. Step back and assess what statements are being made by actions and inaction.
- Help the child "learn to look" with closure, or completeness, to develop organized scanning skills, both visually and tactually. This will not only reinforce any visual input but will also enhance understanding of, and involvement with the world.
- Teach basic concepts by providing purposeful intervention from the child's perspective. Incorporate use of real objects from the interactive world rather than manipulative or imitation toys that are limited to the experience.
- In addition to reinforcement and repetition of activities, allow the child "time to process" both the procedure and what is expected. It takes longer without clear related visual input.
- Apply disability specific information related to visual impairment.
- Believe in the impact of intervention.
- Help the child to be "drawn out" and have fun.
Lois Harrell, Vision Specialist
2531 Morrene Dr.
Placerville CA 95667
New Children's Vision Center
455 University Ave., Suite 330
Sacramento, CA 95825
916-921-1027 or 1-800-834-1007