What is Cortical Visual Impairment?

Cortical Visual Impairment (CVI), also called Cerebral Visual Impairment is the leading cause of blindness and visual impairment in infants and children in the US and other developed countries.

CVI is a neurodevelopmental disorder, not an ocular vision impairment (eye issue or defect). With CVI, vision loss is caused by impact to the visual pathways and processing centers of the cerebral cortex that receive and interpret messages from the eyes.

CVI is most often seen in babies and young children and can continue into adulthood. CVI is a serious and persistent disorder that affects how a child sees and often impacts movement and behavior. Although there is no cure for CVI, functional vision can change and improve as a child matures and through specialized interventions and tailored learning strategies that impact neural connections and brain neuroplasticity. Early diagnosis, specialized learning interventions, vision rehabilitation training, and tools can help those with CVI live a rich and independent life.

Adults can develop acquired cortical visual impairment due to stroke, lesions, tumors, and traumatic brain injury, but symptoms and treatment differ from those of juvenile CVI.

Defining the Condition: What Causes Cortical Visual Impairment?

CVI is most often linked to perinatal (occurring around the time of birth) causes and brain injury, such as stroke or seizure. Often the result of premature birth, such trauma causes insufficient oxygen or blood flow to the vision-processing centers of the brain. CVI can also be caused by central nervous system infections, developmental defects, maternal drug use during pregnancy, twin pregnancy, and some genetic disorders.

How is Vision Affected?

Understanding the role of the brain in visual processing is key to understanding CVI. How CVI affects vision depends on the severity and location of the defect or injury. The four areas of the brain affected by CVI are:

• The occipital lobe, located above the indentation at the base of the skull, is responsible for processing what you see.
• The parietal lobe, spanning the top and both sides of the brain, helps process information that distinguishes multiple objects in relation to one another.
• The temporal lobe, situated parallel to the eyes at the temples, interprets electrical messages sent by the eyes necessary for the recognition of images.
• The frontal lobe helps manage visual memory, distance, and recognition of people, places, and things.

Diagnosis and Assessment of CVI

While there is no specific test to diagnose CVI, the National Institutes of Health (NIH) recently published a working definition to aid medical professionals in identifying and diagnosing CVI. But because it frequently occurs alongside other neurological disorders, CVI is often misdiagnosed or missed altogether. An assessment conducted by the CVI Center of the Perkins School for the Blind found that less than 20% of probable CVI cases in the US are diagnosed.

Key Characteristics of CVI: Recognizing the Behaviors

The American Academy of Ophthalmology recommends a comprehensive eye examination within the first year of a child’s life, and at least once more before starting school. However, since CVI is a brain, not an eye, issue, it is often not detected during an eye exam. As a result, it is critical that parents, teachers, and healthcare practitioners recognize behaviors that are indicative of CVI, which may include:

• Crawling or walking with uncertainty, seeking support from walls or furniture
• Unexplained “clumsiness,” impaired depth perception, bumping into surroundings
• Inability to simultaneously look and reach
• Squinting or head-tilting
• Fixed gaze
• Hesitation when reaching for nearby objects
• Preference for familiar objects rather than interest in new ones
• Difficulty recognizing faces or objects
• Inability to distinguish one item from another in a cluttered field
• Sensitivity to light
• Frustration/fatigue with minor tasks
• Preference for colorful, bright, or moving objects
• Difficulty/boredom with schoolwork or craft projects
• Difficulty at mealtime, not looking at food when eating
• Bringing items very close to see

Conditions Associated with CVI

A 2021 study conducted by the University of Bristol found that 1 in 30 children has some level of CVI. In infants and children, CVI often occurs alongside conditions including cerebral palsy, developmental delay, hearing loss, genetic anomalies including Down syndrome, autism spectrum disorder, and ADHD (attention-deficit/hyperactivity disorder). Studies indicate that more than 60% of children with CVI also have epilepsy.

CVI affects how a child sees, learns, and socializes, making early diagnosis, treatment, and development of compensatory skills vital.  

The Importance of a Functional Vision Assessment

If CVI is suspected, the next step is an appointment with an eye doctor who specializes in low vision. The optometrist or ophthalmologist will conduct a functional vision assessment (FVA), which begins with a discussion about how the child interacts with his or her surroundings. The low vision specialist will also test visual acuity, visual fields (straight-ahead and peripheral vision), how the child sees color, how the child tracks and scans movement, whether the eyes work in unison, and how quickly visual fatigue sets in.

Educational and Therapeutic Management of CVI

A variety of rehabilitative therapies can and should be employed to improve functional vision and help children with CVI realize their full potential at home, school, and in society. These include occupational and physical therapy, assistive technology assessment and training, and speech and vision therapy. With early diagnosis, intervention, education, ongoing support for children with CVI and their families, and the brain’s incredible capacity to rewire damaged connections, improvements of functional vision and quality of life are often within reach.