Cortical Visual Impairment (CVI)
What is CVI?
Cortical visual impairment is caused by nerves that are hurt in the brain, not in the eye. Sometimes it is called neurological visual impairment. "Neurological" means that it is a problem in the nerves or in the brain. Doctors and teachers are learning more about this kind of visual impairment all the time.
People who have CVI often have other disabilities as well. They may have cerebral palsy. That means that their brains have trouble making their body parts move or stop moving when the person wants them to.
Sometimes people who have CVI have a hard time learning the way most people learn. They may need extra clever ways to learn to read or to do math. Or they may learn best by listening instead of reading.
What causes cortical visual impairment?
Cortical visual impairment is caused by nerves in the brain being hurt. This sometimes happens when a baby is being born. Sometimes the baby does not get air as soon as he or she is ready to breath. The brain needs the air to stay alive.
A car crash or a bad fall can also hurt the nerves in the brain. This is called traumatic brain injury. Vision after traumatic brain injury may be a lot like CVI.
What kind of vision do people have who have CVI?
People who have CVI have vision that does not stay the same. The vision may get better as the baby gets older and the hurt to the nerves heals. After a car crash or a bad fall, the nerves may heal as well.
The vision may change all day long. People who have CVI may see something in the morning that they cannot see later in the day. Sometimes people think they are playing games when they cannot see things. They may say, "You saw that before, why don't you see it now?"
Some people who have CVI love to look at lights. Other people who have CVI hate to look at lights. Sometimes it is hard for people who have CVI to see when there is too much light. This is called "glare."
People who have CVI have a hard time looking at more than one thing at the same time. They like to bring things close to their eyes so that they can just see one thing up close. When a plain background is behind the thing they want to look at, it helps them see that thing. It also helps to have things spread out instead of bunched up. When things are bunched up, it is hard for people who have CVI to tell where one thing ends and another begins. Sometimes they just see the outside shape of the whole bunch of things. They do not see the inside shapes.
It can be hard to read for people who have CVI. The letters may look like they are bunched up or crowded. People who have CVI may see only the first letter and the last letter in a word.
Some people who have CVI see better when they are moving, and they see things that are moving better. It is hard for them to read or see pictures when they are sitting still.
People who have CVI need more time to think about what they are doing than people who don't have CVI. When people who have CVI look at something, they sometimes need to stop looking and think. Then they can move their hands to the thing they saw.
Sometimes it is hard for people who have CVI to use their eyes when they are sitting up. It makes them tired to sit up. They need to rest their heads to use their eyes. Sometimes they like to read or look at pictures when they are lying down. They like to have a good chair to lean on when they read.
People who have CVI may feel tired after using their eyes. They may need to take a break from using their eyes.
Sometimes people who have CVI need to look at things from the side of their eyes. Other people may think they are not looking at the right thing.
Some people who have CVI like to look at colors. They see color best.
Many people who have CVI can see things best if the background is very different from the thing they are looking at. If the background is dark and the letters are white or yellow, they can see them. If the background is light gray and the picture is dark gray, it will be hard to see.
What will help you if you have CVI?
- If you have CVI, you may have to tell other people what helps you see. The teacher may not know what will help. Read about the kind of vision people who have CVI may have. Then think about the kind of vision you have. You can make a list of the things that help you see. Let your teacher know what helps you see best.
- If too much light bothers you, wear a hat and sunglasses when you are outside. Make sure the light is behind you or next to you inside.
- Take your time, and tell other people that you need time to look and to think.
- Let people know that you look at things from the side of your eyes if you do that.
- Ask for words to be printed with a lot of space. Make space between the letters. Make space between the lines of words.
- Ask for plain backgrounds. Ask for a contrast between the background and the picture or word.
- If you need to rest, tell people that you need to rest.
- If you see better when you are lying down or resting your head, let people know.
- If there is a color that you like, ask for things in that color. You can have the color you like on your table and chair at school. You can have the color on your backpack. Think of places where you want to have the color you like. It will make it easier to fine your things.
- Ask to hold things that you want to look at. You can hold them close to your eyes. It is OK to be close to the TV or to a computer.
- If you see things better when they move, tell that to your teachers. There are ways to make words move on the computer that will help you see.