CVI : Cortical Visual Impairment ?

Cortical Neurovisual impairments (CVI) are a impaired ability (or inability) of the nervous system (and brain) to transmit and/or process information perceived by the eyes.

They impact vision as well as overall cognitive development.

Even with perfectly healthy eyes, vision can be affected.

Neurovisal disorders impact the daily lives of those who suffer from them.

The consequences are felt at both the physical and psychological levels.

The cognitive repercussions of neurovisual disorders are extremely significant and are often attributed to other factors.

Epidemiological data indicate a steady increase in NDDs (Neurodevelopmental Disorders)

ADHD : 5% of children and adolescents, 2.5% of adults
Dyslexia : 5 to 17% of school-aged children
Dyspraxia: up to 6% of the population
Intellectual disability : 1% in the general population
ASD/Autism : 0.9 to 1.2% of births

Cortocal Neurovisual Disorders in France : 6 to 13% of all children !!!

CORTICAL NEUROVISUAL IMPAIRMENT or DISORDERS ARE AN INVISIBLE VISION DISABILITY.

The leading cause of childhood blindness is called cerebral/cortical visual impairment (CVI/CVD).

Epidemiologically, CVI has become the leading cause of childhood visual impairment in high-income countries and is on the rise in low-income countries.

It affects more than 150,000 children in the United States alone.
CVI / CVD is underdiagnosed.

But the good news is that with early intervention, children or adults with CVI/CVD can learn or relearn to see.
In the United States, fewer than 20% of probable CVI/CVD cases receive a diagnosis.
Adults are also affected : in France, one-third of adults who have suffered a stroke have CVI/CVD.

In India, neurovascular bundles (NVLs) are the cause of visual impairment in 33% of cases, and NVLs combined with other eye conditions were observed in an additional 11% (Pehere NK et al., 2019).

Approximately 33% to 58% of visually impaired children worldwide have cortical visual impairment.

In England, 3.4% of primary school children have vision problems related to cortical visual impairment.

At least 40% of the brain is responsible for vision.

This means that brain damage from various causes can lead to visual difficulties due to a range of visual impairments.

(Stroke / Multiple sclerosis, meningitis, encephalitis...)

According to sources (CVI Scotland), it is mentioned that :

one in thirty children could have a neurovisual disorder...perhaps even two children per class...perhaps more?

Children grow up to become adults, and neurovisual disorders stay with them !

Many adults are affected by cortical neurovisual disorders.

What are the warning signs that might prompt you to seach a professionnel advice?

You need to be more vigilant, if your child experienced difficult birth conditions, trauma, or an infectious disease.

Prematurity
Respiratory distress
Growth retardation
Infectious disease
Gestational diabetes
Head trauma
Antetnatal or perinatal distress
Neonatal stroke
Heart condition

However, it has been observed that children without risk factors can also present with neurovisual disorders!

Are TNVs also observed in people with other disorders or health events ?

When to suspect Neurovisual Disorders?

Who better than parents to observe their children?

If you suspect there are abnormal aspects to your child's behavior...
If you find it difficult to interact with them.

Or if they tend to adopt unusual or unbalanced positions when reading or writing.
If, despite several attempts at rehabilitation/stimulation with learning and vision professionals, you are still unable to help your child progress.

A comic book to understand TNV

Universes impacted by cortical neurovisual disorders ?

How to detect neurovisual disorders or cortical visual impairment ?

Tests developed by researchers from the CNRS (France)* and neuropsychologists allow for the screening of Neurovisual Disorders.
These tests are adapted to children's age groups.
They are observational tests and involve the completion of simple tasks and exercises.
They help to identify the areas of development impacted by Neurovisual Disorders.
They were conducted on a representative sample and are therefore reliable.

*(BAJE Batteries: Battery for the Evaluation of Visuo-Attentional Disorders in Young Children 3 to 36 Months / EVA: Visuo-Attentional Evaluation 4 to 6 Years / EVAGE: Visuo-Attentional Evaluation at 12 Years / BENCO: Battery for the Evaluation of Non-Cooperative Children).

Areas assessed in a screening for visual impairments (All or part depending on age / Non-exhaustive list)
- Visual reflexes (Photomotor / Blink to threat)
- Visual exploration
- Reaction to light
- Fixation and gaze control
- Eye orientation to auditory stimulation
- Visual field
- Visual extinction
- Visual pursuit
- Visual memory
- Visual attention, Exploration
- Perception of overlapping figures
- Color recognition and matching
- Mental imagery
- Shape matching
- Visuomotor coordination
- Symmetries
- Praxis
- Writing

Supplemented by parental guidance with an analysis according to the Perkins CVI* assessment protocol; these assessments provide parents, families, and teachers with:

an understanding of their child,
how they function,
their needs, and
elements to implement.

*CVI = Cortical Visual Impairment = English term for Neurovisual Disorders

Understanding the links between dyslexia, Cortical Visual Impairmeny or Neurovisual Disorders (CVI / CVD) and reading.

Some children start out well with reading and, just as they are ready to move on to more interesting stories, begin to struggle. One reason is the sudden jump from the large, well-spaced text in books for younger children to the much more crowded text in books for older readers.

The difficulty isn't reading ability, but visual development. Some children's visual systems aren't yet ready to cope with dense text, as explained in this short video (less than two minutes) below.

This is a particular problem for children with Cortical (cerebral) Visual Impairment (CVI), where clutter is a well-recognized difficulty.

This short explanatory video traces the evolution of concepts related to dyslexia, from early visual theories to phonological models, and explains why cerebral visual impairment (CVI), sometimes called cortical visual impairment (CVI), can be a missing piece when reading remains difficult despite normal vision. It offers a practical and progressive approach to supporting dyslexic people, including checking their vision and focus, reducing visual distractions and exploring alternatives such as word-by-word reading with the LOOK tool, global word recognition or braille.

Why some children stop reading as they grow up: The influence of Cortical Neurovisual Imairment.

Some children start out well with reading, but just as they're ready to move on to more interesting stories, they begin to struggle. One reason is the sudden jump from the large, well-spaced text in books for younger children to the much more crowded text in books for older readers.

The difficulty isn't reading ability, but visual development. Some children's visual systems aren't yet ready to handle dense text, as explained in the short video (less than two minutes) below.

This is a particular problem for children with cerebral visual impairment (CVI), where clutter is a well-recognized difficulty.

CVI : Cortical Visual Impairment ?

VISION IS THE BASIC FOUNDATION OF ALL LEARNINGS !

What are CORTICAL VISUAL IMPAIRMENT or CORTICAL (Neuro)VISUAL DISORDERS ?

CVI* or CVD** are invisible compared to other disorders... yet they are more numerous !

Detecting Cortical Visual Impairment (CVI) : means being able to rehabilitate them !