Cortical Visual Impairment
Patricia K. Alexander M.S. Ed., Vision Teacher/Specialist
Originally appeared in FOCUS, Vol. 18, No. 4
Cortical Visual Impairment (or CVI) comes under many different labels that continue to evolve and change. It is known as Cortical Blindness, Neurological Visual Impairment, Slow-to See Syndrome, and Delayed Visual Maturation, among other labels. Years ago, children whose vision was difficult to assess in any manner, and was at best inconsistent, were usually determined to be "cortically blind". Twenty-seven years ago when I first started my career as a Teacher of the Visually Impaired (TVI), a child was typically diagnosed as "cortically blind" when the child was difficult to assess or if a child with multiple disabilities had a lack of visual responses.
As the years passed and medical technology continued to advance, many physicians began to understand that children with brain damage often had inconsistent visual responses. It was around this time that CVI became known and widely used as a diagnosis, and the hope for some returning vision was also a part of the diagnosis.
Today we know many things about CVI. We know that it does not affect all children in the same way. In fact, the most consistent thing about CVI is that it is so inconsistent! How it affects a child depends on the injury to the brain, which caused the CVI in the first place, and how the brain is able to compensate.
The causes of CVI are many. Some of them include hypoxia, or lack of oxygen in the brain for a period of time; head trauma; encephalitis; meningitis; and hydrocephalus or even microcephaly. Prognosis is variable and sketchy at best. Vision may recover some or the problems associated with CVI may persist over a lifetime. There is just no way to predict what a child's vision is going to be like. Fluctuating vision is the most common symptom of CVI. This is especially seen in children who have seizure disorders or who are on certain medications such as Dilantin, Tegretol, or Phenobarbital. But all children with CVI have inconsistent responses to visual impairment.
Some of the things I personally have learned as I've had opportunity to work with children who have CVI have been interesting to say the least! For example:
- Children with CVI usually rely much more on their peripheral vision than their central vision. This is one reason why they have trouble being consistent in their responses, since most of the world confronts children centrally and not from the side and unless the child has good neck control, there's not much they can do about letting you know they can't see it. Vision for children with CVI has often been described as looking through Swiss cheese.
- Children with CVI have a delayed response time. It can range from three seconds to fifteen seconds! This could only add to inconsistent responses, especially if not everyone who comes into contact with that child is aware of the delayed response time and doesn't give them enough time to respond!
- Some children with CVI are photophobic or sensitive to bright or outside light. Some are "light-gazers." A "light gazer" will stare at a bright light, bright window light, or even wave their hand or fingers before the light and gaze at it through or around their fingers or hand.
- Color vision is preserved and many children with CVI will have definite color preferences, especially bright colors like neon orange and yellow, but others prefer red or the quieter colors like blue, green and purple.
- Children with CVI tend to prefer moving targets, especially adult-sized and back-lit by window light or similar lighting.
- Children with CVI often have impaired or no depth perception which would impact on their ability to reach for visual targets. This will clearly impact on any gross motor movement as well. Sometimes, children with CVI develop an amblyopia whereby one eye is preferred over the other and therefore, becomes dominant and strong, while the other eye become weaker and weaker with disuse.
- Children with CVI tend to "shut down" when over-stimulated, especially visually. Sometimes, too much light in an environment or too much noise will do it. Many things moving at one time will over-stimulate the child with CVI, simply because they cannot keep up. It is almost a natural defense mechanism for them to cope with the bombardment of sensory information coming at them at once.
- Children with CVI often are unable to look at AND touch a visual target at the same time. They will look at the target, touch it and look away, then (especially if you help them maintain tactual contact) they will slowly return to looking at what they're touching. It is almost as if there is just too much information at once to process, and they need the extra time to do so.
- Children with CVI are inconsistent in their visual functioning. This is the most confining part of CVI for all of us who do not have CVI (not to mention the child who DOES). We should never assume that a child with CVI understands what she is looking at, even though it is a common, everyday object that she interacts with. It is only through slow, careful and consistent presentation that any face/object/activity becomes recognizable to a child with CVI.
Strategies
Now that you have a working impression of how CVI affects a child, how do we help that child see better? Because of the very diverse ways that CVI affects each child, there are MANY different ways to help them use their vision to the best of their ability. Following are some suggestions, but remember: no two children with CVI will respond alike. Each strategy should be considered carefully for each individual child. Some may work for some (with or without alteration) and some may not work, no matter what you do. It is trial and error and the trick is in finding what works best for that one specific child and build on that strategy!
- Look for the best response and be alert to where in their field of vision this occurs OR which way your child is turning their head and/or eyes to look. This is where positioning comes in, as well. It is VERY important that your child's position is best for looking behaviors without your child having to do too much work just to hold themselves upright. Give them support so that they may concentrate on the visual task.
- ALWAYS give several seconds for your child to respond to ANYTHING! If you are aware it takes your child some amount of time to respond, note exactly how long and tell EVERYONE who works with her. Also, because they work so much harder just to locate the visual target, allow for breaks and then go back to the activity when your child appears to be ready to work hard again.
- Check for too bright lighting. Children with CVI usually do not need things to be bright around them, only the things we are asking them to look at should be bright and in good contrast! Also, keep the environment around them (at home and maybe at school) as simple as possible. When you're out, keep something familiar with them that they can focus on and help them cope with the over-stimulating environment around them.
- Find your child's favorite color and use it! This might be the color that you get her cups, toys, activities, whatever in. Color happens to be strength in children with CVI, so use that to help encourage visual attention. Then make sure everyone who works with your child knows this.
- Use movement to get your child's visual attention, even with visual stuff. Move them across their peripheral field or central, and note where the most consistent visual responses occur. Remember that often, children with CVI have better peripheral vision than central. Help them position themselves to find their best view and NOTATE IT!
- Repetition is important. It might be boring for you, but repetition helps the child with CVI learn about what they are looking at or touching. This is also why it is important to use familiar objects, too.
- Touch is an important part of supplementing visual information, however, children with CVI have a tendency to be unable to immediately process BOTH senses. Help them by keeping their hand on the object or physically prompting and assisting their touch until they can coordinate both touch and look simultaneously. Because depth perception is affected, this would also help them acquire the ability to reach and find something they are looking for.
- Learn to interpret responses that your child may have that are very subtle. These can include change in breathing pattern, eye gaze shift, or body position changes. When you get consistent responses and can identify them, make sure everyone that works with your child knows what they are.
- Remember with ALL new information (especially in the classroom), the best strategy is to break down the information presented into its smallest steps so you may teach it systematically and repetitively. Too much information is again, over-stimulation and your child will not be able to visually (tactually or auditory) process the information very well.
- Give lots of praise for the smallest steps. Give lots of hugs!
CVI continues to confound professionals and parents alike. We can only hope to do the best we can and when we find a successful technique, we should SHARE with everyone we know who works and/or lives with children with this disability. It is through trial and error that we can learn more about his disability. It is through sharing that help others learn as well.
