What is CVI?
CVI is a condition where a reduced visual response occurs due to damage to the posterior visual system in the brain. Typically the eye structure itself is normal. CVI is one of the most common causes of severe visual impairment among children in developed countries.
What causes CVI?
CVI is caused by any damage in early infancy to the visual parts of the brain. These include: stroke, decreased blood supply, decreased oxygenation, brain malformation or infection, hydrocephalus (increased pressure in the brain), seizure, metabolic disease, head trauma or other neurologic disorders.
What symptoms of CVI?
- Variable levels of visual loss, often demonstrating fluctuations over time
- Poor attention to visual stimuli, particularly complex visual and environmental stimuli
- Delay in response to visual stimuli
- Difficulty with visualizing new surroundings or objects
- Light gazing
- Preference for viewing objects at close range and odd angles
- Better vision when viewing moving objects compared to stationary objects
How is CVI diagnosed?
The diagnosis of CVI is based on typical visual symptoms and exclusion of other causes of visual loss via a thorough eye examination performed by an ophthalmologist.
Is CVI the same as “Cortical Blindness” or “Delayed Visual Maturation”?
Cortical blindness is an inaccurate description of CVI and this terminology should not be used as many children with CVI do have some vision. “Delayed visual maturation” is typically seen in an infant with normal eyes but showing no or poor visual behaviour in the first a few months of life. It differs from CVI as visual function often normalises by the age of 6-9 months.
What is the visual prognosis for children with CVI?
As the brain matures, new connections can develop in the brain to overcome the initial injury or deficit and improve function. Some vision improvement may be seen in many children with CVI however it is difficult to predict longer term visual function for any given child.
What is the treatment for CVI?
There is no definitive treatment for CVI per se but treatment of any underlying neurological disease is essential. This often involves a multidisciplinary approach with the involvement of a paediatrician, ophthalmologist as well as other health and education providers. Children should be enrolled with BLENNZ as soon as possible when the diagnosis is established so that early intervention to help stimulate visual development can be provided. Resource Teachers of Vision can provide a functional visual assessment focused on the specific characteristics commonly found in children with CVI.
What is useful information/‘tips” regarding children with CVI?
- Extra time for responses to visual stimuli
- Avoidance of over stimulation
- Avoidance of visual tasks when a child is hungry, tired, frustrated
- Use of large, highly contrasted, lighted, reflective and moving objects
- Use of touch or sound to attract a child’s attention
- Visual materials presented in a simple uncluttered manner with increasing complexity (as tolerated)
- Presentation of visual material from different directions/angles