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The doctor can't find anything wrong with your child's eyes but your child can't see. What does it mean? The answer may be that your child has a cortical visual impairment. CVI is a condition in which the eye works, but the part of the brain which interprets the signals provided by the eye does not. This will cause the child to have difficulty using the visual input he/she is receiving.
The causes of CVI include but are not limited to hypoxia, or a lack of oxygen in the brain for a period of time; meningitis; head trauma; encephalitis; and hydrocephalus. Vision may be recovered, or the problem may persist over the lifetime. The visual functioning of children with CVI may also vary from day to day. A factsheet about CVI, which is also sometimes called neurological visual impairment, indicates that certain medications used for seizures can also cause children with CVI to experience additional visual difficulties.
CVI does not affect all children in the same way. (Morse, 1999) It may cause problems with recognition of faces, interpretation of abstract symbols such as print or line drawings, or depth perception. It may occur in combination with a visual field loss. How it affects a person depends on the injury to the brain which caused the CVI and how the brain is able to compensate. Cognitive ability will also influence the child's ability to develop techniques for interpreting what he/she sees, and emotional factors, stress, or fatigue may influence how much he/she is willing or able to use his/her vision.
Difficulties with processing visual input may cause some children to be distractible or to perform poorly in school. An understanding of CVI can enable teachers to help students to succeed and develop techniques for coping emotionally as well as physically.
Children with CVI are often attracted to bright lights or colors. One mother found that putting brightly colored toys on a dark background or using a light box to illuminate toys helped her child to focus on the toys. She noted that her child often looked for a brief period, then looked away, then looked again. Children with CVI may become overwhelmed by visual stimuli and avert their gaze or use other means to understand what they are seeing. (Morse, 1999)
One adult with CVI developed some strategies for learning to interpret pictures. She used flash cards and picture dictionaries to match pictures with words. She emphasized the importance of using these exercises early in life because the brain is more able to absorb new information and build neural networks during the early years.
Andrea Story, a teacher of blind and visually impaired infants and toddlers from Anchorage, provided some suggestions for helping children with CVI learn to interpret pictures.
"The simpler, less busy picture may be easier for the child with CVI to interpret. Some of the artists styles are already simple and have little clutter (such as 'Are you my Mommy?'). Other books are much more complicated visually and busy (such as 'Is your Mamma a Llama'). I had success adapting children's books for one child by cutting out the main characters or object on each page and gluing them to a page that was a solid background. These pages were then bound together for a 'new' less cluttered book. I had to buy two of the same book to reproduce the whole book because of the pages being printed back to back. It worked well with a Barney book that was mostly photographs and with 'Is Your Mamma a Llama'. Both of these books have a little too much going on in the background.
The use of color is good. ('color vision is generally preserved in children with CVI (color perception is represented bilaterally in the brain, and is less susceptible to complete elimination'). Another child I worked with could easily identify any size Winnie the pooh (distinct yellow and red color) as well as piglet (pink). However given the same pictures in black and white and she was not able to do as well."
Attention to sound and tactile stimuli not only provide alternative means of learning,but some professionals believe that these serve as a stepping stone for some children with CVI to learn to use their vision as they understand what their ears are hearing or what their hands are doing. (Morse, 1999)
Children with CVI may experience improvements in visual functioning over time. One mother found that repeating short periods of visual exercises helped her child to learn to process certain kinds of information. These exercises also involved tracing, which demonstrates the power of the tactile/kinesthetic input.
Parents and teachers of children with CVI emphasize the importance of perseverance and making learning fun for the child. The individuality of children with CVI is also an important factor in planning interventions.
More information about CVI is available via the links on the CVI links page.
California Deaf-Blind Services. Neurological visual impairment factsheet
Morse, Mary T. (1999). Cortical visual impairment: Some words of caution. Re:View; 31(1) 21-26
This document is copyright 2003 by Sarah J. Blake. For permission to reprint, please email Sarah at sarah@growingstrong.org.
Sarah J. Blake is a person with a visual impairment who has also studied blindness and eye conditions. She is not an eye care professional, and information on this site is not a substitute for face-to-face consultation with an eye care professional. This site is designed solely to assist patients and doctors in building cooperative relationships.
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