What is CVI?

Adapted from article by Rachel Bennett and Kara Baskin

CVI is a brain-based visual impairment caused by damage to the visual pathways or visual processing areas of the brain.

Cerebral/Cortical Visual Impairment (CVI) is the leading cause of childhood blindness and low vision. CVI is a lifelong brain-based visual impairment, caused by damage to the brain’s visual pathways or visual processing areas. 

Children with CVI struggle with visual attention and visual recognition resulting in a lack of access for understanding the world around them. Some children see the world as distorted and unrecognizable. Others can focus but might struggle to understand what they see. A crowded setting, a hot day, or fatigue has the potential to make vision use nearly impossible. 

Children with CVI often display common visual behaviors and traits, but CVI manifests differently in everyone. Some children have trouble with facial recognition, hand- and foot-eye coordination, or integrating vision with other senses. These behaviors may change and improve over time, but they never disappear. As such, children with CVI often develop unique compensatory skills to manage their confusing visual world. Support for CVI needs to be sustained and lifelong.

With CVI, the brain has difficulty converting the raw data from the eye into a reliable, meaningful image of the world that can be interpreted and acted upon. Matt Tietjen, CTVI and leader in the field

Why is CVI so misunderstood?

Often, people associate blindness and low vision with ocular — or eye — impairment. But CVI is a neurological issue, where the brain has trouble processing what the eyes can see. Some children with CVI have perfectly healthy eyes, which can cause diagnostic confusion, though others have refractive errors or misalignment. Many others have coexisting ocular conditions that mask their CVI.

There’s no standard diagnostic test for CVI, which makes it hard to identify. There is growing research that suggests many people with CVI also have overlapping conditions, such as cerebral palsy, autism, or Down Syndrome, which can make diagnosis even more complex.

Significant numbers of children with CVI are being misdiagnosed and mislabeled, which prevents them from accessing effective teaching strategies. Importantly, the National Eye Institute and National Institutes of Health have now identified CVI as a research priority.

Some children may have difficulty visually attending to objects and their environment. While those with better visual attention can exhibit some focus, they still struggle to understand what they see. They become overwhelmed by so much meaningless visual stimulation because their brain has trouble perceiving it. This overstimulation often causes children with CVI to avoid looking at objects and the people around them. They may stare at light and appear very visually impaired. If they do attend to objects and people in the world, they might struggle to recognize those objects and people. Other children with CVI look at objects but lack understanding of what they see. They might appear to have learning difficulties or become anxious in new environments. Many have CVI meltdowns due to fatigue or challenges with sensory integration.

Because of those symptoms, CVI is sometimes misdiagnosed as an emotional or psychological disorder. Common misdiagnoses include ADHD, autism spectrum disorder, delayed visual maturation or learning disabilities. However, CVI is its own diagnosis. Once accurately diagnosed, targeted evaluation and instruction will support access to learning and building compensatory and visual skills.

CVI is often one piece of a child’s complex diagnosis.

If you’ve met one child with CVI, you’ve met one child with CVI. Dr. Gordon Dutton

7 facts to know about CVI

1. It is the most common cause of blindness and low vision in children. It is the leading cause of congenital blindness (vision loss at birth) in the United States.
   
2. CVI is extremely underdiagnosed. Less than 20% of likely U.S. cases are diagnosed. For every diagnosed child with CVI, there are four more likely cases of CVI.
3. One study shows that up to 1 in 30 kids have CVI-related visual difficulties.
4. CVI is common in neurodevelopmental conditions, and complications from premature birth, lack of oxygen, pediatric stroke, and genetic conditions are common causes of CVI.
5. Several studies show that up to 70% of kids with Cerebral Palsy have CVI, 64% have epilepsy, and 72% have developmental delay. One study shows that 38% percent of participants with Down Syndrome have suspected CVI. 
6. It causes children with healthy eyes to have difficulty processing what they see. Someone with CVI could have perfectly healthy eyes and still be functionally blind or have low vision. And many with CVI also have ocular conditions.
7. It causes individuals to display some unique visual behaviors and traits commonly seen when there is damage to the brain’s visual system

Children and adults with CVI have different severity levels of visual impairment. There’s no one-size-fits-all model, and each child is unique. No matter how CVI manifests, it’s a big deal for the individual.

“Information is landing on your eyes, but you can’t make sense of it. You can’t wrap your head around things you’re seeing. You can’t tell where one object ends and the next begins. You are looking at things, but you don’t know what you are looking at. You try to look closely and maybe you can make out light coming through a window or the color red enters your awareness, but these few data points are barely enough to give you an overall sense of your environment. You can’t glean much meaning from the visual cacophony that surrounds you. Your eyes’ ability to see does not serve you in this situation. ” -Nai, adult with CVI and author of The CVI Perspective

Common visual behaviors of CVI

Every child’s visual journey with CVI is unique, and a diagnosis is often made by ruling out other causes. However, there are common CVI visual behaviors and traits associated with CVI. They are:

Appearance of the eyes: This is an assessment of alignment and eye preference. We assess whether both of your child’s eyes are pointed straight or whether one eye is turned in with the other turning out. Does your child favor or use one eye over the other? Does she alternate?

Movement of the eyes: This is an assessment of ocular (eye-related) motor skills. We look at the way both of your child’s eyes move in different directions: horizontally, vertically, and diagonally. We analyze shift and gaze and how she responds to a moving target.

Visual attention: This is an assessment of your child’s ability to look and sustain gaze for recognition. For example, your child might focus on only one small area while unable to process or understand other items. We consider her ability to maintain gaze in cluttered and un-adapted environments, as well as her ability to maintain gaze while ill or tired.

Access to people: Your child might have difficulty looking at faces and difficulty with facial recognition. Some kids have trouble interpreting facial expressions. For example, you might smile, and she won’t smile back or look into your eyes. Many parents describe their child looking “through” them or past them.

Response interval: This is an assessment of her degree of delay in visual attention and delay in visual recognition. Your child might take a long time to look at an object and a long time to understand what she’s seeing.

Visual guidance of the upper limbs: This is an assessment of reaching while maintaining visual attention, reaching accuracy, and looking while exploring an object. Your child might hold something in her hands but can’t look at it, or she might gaze off into the distance while playing with an object. Or she might over- or underestimate her reach or reach tentatively.

Visual guidance of the lower limbs: This is an assessment of her ability to step accurately or to place her foot accurately, such as into a shoe.

Sensory integration: This is an assessment of the impact of competing sensory input on her vision use. Your child might not be able to listen or feel a vibration while busy looking.

Visual field abilities: This is an assessment of visual field awareness and abilities to recognize materials in all fields. Your child might not respond to items in a particular visual field, such as peripheral, left and right, upper and lower. Or she might pay more attention to one side, with a visual deficit in another.

Impact of motion: This is an assessment of her need for motion to gain visual attention; the distraction of environmental motion; the inability to follow fast-moving items; impaired perception of motion (speed, distance or direction of motion); and a phenomenon called blindsight (the ability to avoid objects while moving, without awareness of the obstacle). Your child might need an object to move to know it’s there. Or she might have trouble assessing distance and speed, such as a ball or car coming toward them.

Impact of spacing/object arrangement/clutter: This is an assessment of the number of objects your child can tolerate in a display. Sometimes spacing items out improves kids’ visual attention and visual recognition. Your child might have trouble with visual clutter — when too many things are in an environment, they might blend together. Or she might be able to identify items in a predictable line but not scattered on a table, because it’s too visually complex.

Form accessibility: This is an assessment of the “accessible form.” Think about a common figure, like Donald Duck: Even though it’s a cartoon, we know it’s a duck. A child with CVI might have trouble making that distinction. Your child might see three-dimensional items but have trouble with photos, for example. Or she might see color but struggle with black and white line drawings.

Impact of color: This is an assessment of how your child reacts to different colors and black and white, how she uses color for visual attention and object recognition and how she uses it as an overall strategy function. Many kids with CVI prefer one color over another. We try to see how color helps her understand the world.

Impact of light: This is an assessment of the distraction of light, need for light, light sensitivity, attraction to light and need for backlighting. Your child might be so impacted by light that it’s just a visual target; other kids benefit from lighted objects.

Visual recognition: This is an assessment of your child’s abilities to visually recognize known items or known classes of items. Your child might immediately recognize her favorite toy or cup but might not recognize a similar, unfamiliar object.

Visual curiosity: Think about going to the grocery store. A child is constantly learning about shapes and objects as she watches mom or dad load up the conveyor belt from her perch in the carriage. A child with CVI might not absorb those incidental life lessons. This is an assessment of the accessibility of “incidental learning” for distance materials and events with and without compensatory supports and for all visual fields.

Adapted from article by Rachel Bennett and Kara Baskin, CVI Now Perkins School for the Blind

References:

• Dutton, G. & Lueck, A. (2015). Vision and the Brain: Understanding Cerebral Visual Impairment in Children. New York, New York: American Foundation for the Blind Press.
• Roman-Lantzy, C. (2018). Cortical Visual Impairment: An Approach to Assessment and Intervention. 2nd ed., New York, NY: AFB Press.
• Teach CVI (2017).  Tools for educators and health care providers. Retrieved from: https://www.teachcvi.net
• Tietjen, M. (2019). The “What’s the Complexity?” Framework. In Roman-Lantzy, Christine. (2019) Cortical Visual Impairment: Advanced Principles (pp. 92-150). Louisville, KY: APH Press