I recently attended a conference so I could educate myself on CVI, one of the diagnoses my son has. When you have a child with multiple disabilities, it can be tough to decide which one to prioritise or focus on. After this conference and digesting what I learned there, I am definitely moving CVI to the top of the list.
The following information is from Dr. Christine Roman-Lantzy, a researcher and specialist in CVI. I’m not a doctor, nor do I play one on the internet. Please consult your child’s medical team with specific concerns.
What is CVI?
There are two types of vision impairment – those that are eye based (a problem with the actual eye) and those that are brain based (a problem with the brain). CVI is brain based, where there is damage or atypical structures in the visual pathways. Visual processing is compromised to varying degrees. The eyes get the image and the brain perceives it, however it cannot categorise or sort the information. This is why glasses do not fix the problem. Children may look at objects, frequently, but looking at an item does not mean that they are able to interpret it.
What can cause CVI?
Including, but not limited to: asphyxia, hypoxia (a lack of sufficient oxygen in the body’s blood cells), or ischemia (not enough blood supply to the brain), all of which may occur during the birth process; developmental brain defects; head injury; seizures, hydrocephalus (when the cerebrospinal fluid does not circulate properly around the brain, and collects in the head, putting pressure on the brain); infections of the central nervous system, such as meningitis and encephalitis; neurological conditions such as chromosome disorders; hypoglycaemia, periventricular leukomalacia, and traumatic brain injury.
Ten characteristics of CVI
Preference for a specific colour – the child will be drawn to rich highly saturated colours, usually red and yellow, but it can be any colour.
Need for movement – especially rapid movements. The child may fixate on fans or similar objects. An older child (in the classroom) may not be able to avoid being visually distracted by a ceiling decoration, movement in the hallway or outside a classroom window. This includes shiny things and other items that may draw their attention.
Visual latency – the child’s visual responses are slow and often delayed. They will need to wait in order to respond, but with proper interventions their latent times can greatly improve.
Visual field preference – the child will prefer to look at objects in a particular area.
Difficulty with visual complexity – not seeing an object when other stimuli, such as sounds, are present. If an environment is sensory complex, the child has to choose which sense they are going to attend to. This includes the ability the analyse faces, which are very visually complex. This means that they will often avoid looking at unfamiliar faces.
Light-gazing and non-purposeful gaze – since the child cannot sort and categorize what they are seeing, if they cannot find something meaningful (to them) to look at, they will have a non-purposeful gaze. Often the child will stare at light too.
Difficulty with distance viewing – often mistaken for near-sightedness. This is due to what could be a visually complex environment. In these instances, the child will use memory to override their vision skills, which then makes it appear as if they can see because they will be able to navigate familiar environments based on memory.
Atypical visual reflexes – not blinking when you tap the bridge of the child’s nose or come too close to the eyes. They have a delayed protective blink response.
Preference for familiar objects – this is often confused with a hyper-interest in something, since they will fixate and show preference for the familiar. They prefer objects that they already know, so the brain doesn’t have to “sort” the information.
Absence of visually guided reach – the child’s ability to look at an object while reaching for it is impaired.