Cortical visual impairment (CVI)

What is cortical visual impairment (CVI)?

Cortical visual impairment (CVI) is a disorder caused by damage to the part of the brain that processes vision. It is more common in children than adults. CVI is a leading cause of permanent visual impairment in children in the United States.

What is the difference between cortical visual impairment and cerebral visual impairment? 

The terms “cortical visual impairment” and “cerebral visual impairment” are often used interchangeably for the meaning of CVI. The cortex is the surface part of the brain that provides complex processing while the cerebrum includes the cortex as well as deeper brain structures.

Because the medical and scientific communities have started to recognize that CVI involves many areas of the brain — and not just the cortical areas — “cerebral visual impairment” has become the more prevalent meaning of CVI.

Visual disturbances caused by CVI are neurological in nature and cannot be corrected with glasses. This is different from ocular visual impairment, which is caused by issues with the eyes themselves. CVI also does not affect visual acuity, contrast sensitivity, depth perception, visual field or color vision.

What causes CVI?

CVI is most often caused by damage to the brain before, during or soon after birth. Causes of brain damage in babies and newborns include:

• Hypoxia or hypoxic-ischemic encephalopathy (HIE) – Lack of oxygen to the brain (this is the most common cause of CVI)

• Periventricular leukomalacia (PVL) – Damage or injury to the white matter of the brain

• Hydrocephalus – Fluid buildup in the brain

• Meningitis, pneumonia, and other infections that lead to brain damage

• Epilepsy – Neurological seizure disorder

• Trauma to the head, like that from shaken baby syndrome

CVI can also be caused by:

• Congenital brain malformations

• Hypoglycemia

• Metabolic disorders

• Stroke

• Brain tumors

• Defects of the central nervous system

• Cardiac arrest

• A twin pregnancy 

• Prenatal drug use by a baby’s mother

Premature babies have a higher risk of developing CVI because of the complications associated with preterm birth.

Diagnosis

There is no test for CVI, so making a diagnosis can be difficult. However, there are three main criteria that are used to diagnose CVI:

• A history of neurological issues, which could have occurred due to trauma, brain damage, or abnormal development, to name a few.

• Irregular eye behavior that cannot be explained through an eye exam.

• The child presents unique visual and behavioral characteristics that are typically seen with CVI.

Overlapping conditions

A variety of health conditions often overlap with CVI, which can also make diagnosis challenging. 

The most common condition seen with CVI is cerebral palsy, a disorder that affects movement, balance, and coordination. Studies have shown that 50% to 70% of children with cerebral palsy also have CVI. 

Other conditions that are often present with CVI include: 

• Down syndrome

• Epilepsy

• Autism

• Hearing loss

• Developmental disabilities

What are the symptoms of CVI?

Symptoms of CVI are not typically detected during a standard comprehensive eye exam, though they may have abnormalities in the optic nerves. Strabismus, or crossed eyes, is also common. However, most children and adults with CVI appear to have healthy eyes and normal vision. This is because the problem is in their brain and not their eyes. 

There are 10 main behavioral characteristics often associated with CVI. They are:

• Preference for looking at objects that are certain colors. It’s common for a child with CVI to show preference for toys and other items that are red, yellow, or in rich, saturated colors. 

• Excess interest in light that can cause a child to gaze directly at a light. Over time, they may not gaze at lights, but may still need backlighting.

• Preference for looking at moving objects versus static objects. You may need to shake an object in front of the child in order to get their attention. 

• Difficulty reaching for objects. Using peripheral vision may be preferred when reaching for an object. A child may also look at something, look away, and then reach for the object without looking at it.

• Slower processing time when looking at objects. This is referred to as visual latency.

• Difficulty with visual complexity. In other words, it’s difficult to focus on something in a busy environment with lots of people and/or activity. 

• Having abnormal visual reflexes. If something moves toward the child’s face, they may not instinctively blink like someone who does not have CVI. This may be more apparent in a noisy environment.

• Difficulty with vision in unfamiliar places but better vision at home. This is called visual novelty.

• Preference for certain visual fields. A child may only look at something that is in a specific position, such as left, right, up or down.

• Difficulty seeing objects at a distance. A child may prefer to look at items that are close by, even though their eye exam shows they have normal vision.

Someone with CVI may also: 

• Become tired after doing visual tasks

• Have inconsistent responses to familiar objects

• Prefer to use their sense of touch over their sense of sight

• Avoid tactile stimulation

• Experience light sensitivity (photophobia) 

• Avoid direct eye contact

Phases of CVI

Three CVI phases and their associated scores are used to help describe a patient’s level of visual function in addition to their strengths and needs. 

• Phase I – This phase ranges from 0 to 3. Patients in this range have the lowest level of visual functioning. 

• Phase II – This phase ranges from 3 to 7. Patients in this range have a moderate level of visual functioning. 

• Phase III – This phase ranges from 7 to 10. Patients in this range have the highest level of visual functioning.

This information is also used to determine which interventions, techniques and adaptations will be most beneficial to an individual patient. 

How is CVI treated?

There is no specific treatment to cure CVI, but there are rehabilitation techniques that can help improve a CVI patient’s quality of life. Many of these can be done at home after discussing what will work best for your child with their medical team. 

For example, you or your child’s rehab specialist can:

• Perform light reflex stimulation therapy in a quiet and dark room. Shine a flashlight in their eye for a brief moment. After pausing for five seconds, shine the flashlight in the other eye. This is done for one minute at a time and is repeated 30 times a day. 

• Make an object’s outline easier to see by shining a penlight on it for one minute in a darkened room.

• Help with shape recognition by cutting shapes out of white cardboard and placing them onto a black background. The shapes can also be cut out of black cardboard and placed on a white background. These can be shown to your child 10 times a day. 

• Keep your home environment uncluttered and use high-contrast colors to make it easier to identify different objects. 

• Look for large-print and double-spaced books to help your child read more easily. 

• Help your child with facial recognition by asking family members and other regular visitors to wear the same color each time they come over.

It can also help a child with CVI to: 

• Allow extra time to complete a task

• Use sound or touch to get their attention

• Dim the lights in their room 

• Show them an object from different angles

• Avoid giving them visual tasks when they are tired, hungry or getting frustrated 

• Avoid overstimulation 

Rehabilitation and treatment varies from one person to the next. An individualized and multidisciplinary approach is important. In some cases, a child’s vision can improve on its own over time, but early intervention is important to ensure a child can get the most out of their vision. 

Is cortical blindness the same thing as CVI?

Cortical blindness is an old name for CVI that is now considered incorrect specifically because a child with CVI can still see. In fact, their vision may even improve. 

Cortical blindness (CB) is vision loss resulting from damage to the occipital cortex. This is a separate condition that can affect children or adults. Incomplete cortical blindness is more common than complete cortical blindness, so it’s possible someone with CB will still have some light perception. 

Page published on Tuesday, November 7, 2023

Page updated on Tuesday, November 14, 2023

Medically reviewed on Monday, November 6, 2023