Cortical Visual Impairment (CVI)

How CVI differs from eye-based vision loss

Vision depends on the eyes collecting images and the brain making sense of them. In CVI, the eyes and optic nerves may work normally, but damage to the visual pathways or the visual cortex at the back of the brain disrupts processing. A standard eye exam may therefore be normal or show only mild problems, while the child's functional vision is significantly impaired.

Causes

• Hypoxic-ischemic brain injury around birth (lack of oxygen or blood flow)
• Premature birth with periventricular leukomalacia (damage to white matter near the brain's fluid spaces)
• Neonatal or childhood stroke
• Infections: meningitis, encephalitis, congenital infections such as cytomegalovirus
• Hydrocephalus and shunt failure
• Brain malformations and genetic conditions
• Traumatic brain injury, including abusive head trauma
• Severe low blood sugar in newborns
• Epilepsy with frequent seizures
• In adults: strokes affecting both occipital lobes cause cortical blindness

CVI frequently occurs alongside cerebral palsy, epilepsy and developmental delay.

Signs of CVI in children

Children with CVI often show characteristic visual behaviors:

• variable vision: sees better on some days, at some times or in familiar settings
• color preference: often for bright red or yellow
• attraction to light: stares at lights or windows
• attraction to movement: notices moving objects more easily
• visual latency: a delay before looking at something
• visual field preferences: sees better in some parts of the visual field, often the lower field is affected
• difficulty with complexity: struggles to find objects in cluttered scenes, patterned backgrounds or crowds, and to recognize faces
• better near than distance vision
• looking away while reaching for an object
• difficulty with novel objects compared with familiar ones

Some children have milder "higher-level" CVI, with normal acuity but trouble with crowded pages, navigation, recognizing people or judging depth, which may be mistaken for learning or attention problems.

Diagnosis

• Full eye examination by a pediatric ophthalmologist to identify or rule out eye conditions, which can coexist
• Functional vision assessment by a teacher of the visually impaired or vision specialist, using structured tools such as the CVI Range
• Review of history: prematurity, birth complications, seizures, brain injury
• Brain MRI showing damage to visual pathways
• Visual evoked potentials (VEP): measure the brain's electrical response to visual stimuli

There is no single test. Diagnosis combines a history of brain injury, characteristic visual behaviors, and an eye exam that does not fully explain the vision difficulties.

Support and intervention

There is no medicine that repairs CVI, but the brain's plasticity, especially in young children, means visual function often improves with appropriate support.

Adapting the environment

• reduce clutter and use plain backgrounds
• use favored colors to highlight important objects
• add movement or light to attract attention
• present one item at a time, at a comfortable distance
• give extra time to look
• use consistent, familiar objects and settings
• reduce background noise and distractions during visual tasks

Professional support

• early intervention services from infancy
• a teacher of students with visual impairments (TVI)
• occupational, physical and speech therapy
• orientation and mobility training
• individualized education plans with visual accommodations
• treatment of coexisting eye conditions such as squint or refractive error

At home

Parents can learn to recognize their child's visual preferences and use them in play and daily routines. Organizations such as Perkins School for the Blind and the American Printing House for the Blind offer family resources.

Outlook

Outcomes vary widely. Many children show meaningful improvement in functional vision over years, especially when CVI is identified early. Some remain significantly visually impaired. CVI is lifelong, and the needs of older children and adults shift toward reading, navigation and independence.

Frequently asked questions

What is cortical visual impairment?

It is vision loss caused by damage to the brain's visual pathways or visual cortex, rather than by a problem with the eyes. The eyes may look normal, but the brain has difficulty processing what they see.

What causes CVI in children?

Common causes include lack of oxygen around birth, premature birth with white matter injury, stroke, brain infections, hydrocephalus, brain malformations, head injuries and genetic conditions. It often occurs alongside cerebral palsy or epilepsy.

Can cortical visual impairment improve?

Yes, often. Because young brains are adaptable, many children's functional vision improves over time, especially with early intervention, adapted environments and specialist teaching. The degree of improvement varies.

How is CVI diagnosed?

Doctors combine a history of brain injury, characteristic visual behaviors, an eye exam that does not fully explain the vision problems, functional vision assessment and brain imaging. Visual evoked potential testing is sometimes used.

Is CVI the same as blindness?

Not usually. Most people with CVI have some vision, which can vary from day to day and depends on the environment. "Cortical blindness" describes severe cases, but many children with CVI use their vision in meaningful ways.