Does your brain understand what your eyes are seeing?
I see a lot of children with CP in my paediatric hospital eye clinic. The purpose of this clinic is to identify and manage conditions such as eye turns (strabismus), lazy eyes (amblyopia), spectacle corrections (refractive errors) and abnormal findings of the eye itself. These conditions are more common in CP and it is important to get these assessed.
As eye care practitioners, we are used to dealing with conditions of the eyes. However, I would argue that it is at least as important to identify and address issues arising from the visual areas in the brain: The areas that are responsible for interpreting what we see with our eyes. The medical term for this is cerebral vision impairment (CVI). About two thirds of children with CP have a degree of CVI.
Reduced vision
Reduced vision = ability to see small details
Children with quadriplegia are most at risk of reduced vision, which cannot be fully explained by conditions of the eye. This can be the case in diplegic children, but usually to a lesser extent. Children with hemiplegia often have normal vision. Reduced vision is often associated with other visual difficulties.
Reduced contrast sensitivity
This renders it difficult to see objects against a background of similar colour. Creating an environment with bold colours against plain backgrounds can be helpful.
Lower visual field impairment
Most people can see the ground ahead of them when they walk, but this may not be the case in some children with CP. For children with a lower field impairment, it can be tricky to negotiate uneven ground, floor boundaries, steps and kerbs as they cannot process this part of their visual field without conscious effort. Field impairments in CP are most commonly in the lower area, but it can also occur on the right or the left side.
Abnormal eye movement
It can be difficult for a child with CP to follow a slow moving target or to switch attention from one target to another target. Sometimes, we see a delayed reaction to a moving target, so it is important to give the child time to respond.
Processing and analysing complex visual information
Busy environments with a lot of noise, movement and clutter demand a great deal of energy for processing all the information. Whilst a healthy brain can usually create an overview and zoom in to see relevant details, a child with CVI may find such an environment rather overwhelming.
How do I know what my child can see?
Some children with CP respond well to formal clinical tests, whilst others may not be able to participate fully. It is therefore important to adapt the assessment to the child’s situation. An experienced practitioner can also make meaningful observations in the clinic room. The use of question inventories and history taking by a CVI specialist can reveal a lot about the visual world of the child.
To book a CVI assessment (online or in-person in Edinburgh), contact Cirta:
