Cerebral visual impairment and PMLD

On this page Janet Harwood, CVI (Cerebral Visual Impairment) Society, explains how to assess vision impairment in children with PMLD and more about CVI.

Early intervention can take full advantage of any potential for the child’s brain to develop and find different ways (sometimes called neural plasticity) to process sensory information and movement. Vision helps us to make sense of everything so every child needs the opportunity to develop their visual potential. Carefully structured support can make a huge difference to the ability of children who may not be able to make sense of what they “see” to engage with the world.

What to look for

You may notice some of these visual behaviours:

• reaching for objects to the side but not straight ahead
• looking away from people or objects in order to “see” them
• vision which seems variable and may change on an hourly or day-to-day basis
• For the mobile child – inaccurate visual guidance of movement and reach for objects
• inability to look at objects for any length of time
• irregular eye movements
• lack of response to objects on a “busy” background that the child would respond to on a plain, contrasting surface
• eye movements not made independently of head movements
• difficulty seeing objects unless they are moving, or in other children, unless they are still
• Lack of response to faces or facial expression.

Assessment

Talk to people who know the child well about their observations of the child’s visual behaviours. This should include discussion with the child’s family, if possible, in their home. Some children show more visual response at home surrounded by familiar objects which their brain has had repeated opportunities to recognise.

For the QTVI, observation is just as important as direct “work” with the child to observe visual patterns and behaviours as well as use of other senses which may confuse visual responses. Consider how different environments affect the child’s use of vision.

Some key assessment questions

• At what distance do they respond to visual stimuli?
• How does contrast sensitivity affect their visual access?
• At what distance, if at all, can they respond to faces?
• Do they prefer or respond better to particular colours? If unsure, try “warm” colours such as red, orange or yellow as these are often responded to more readily.
• How do they respond to large clear targets such as “Puppet Face” (see Additional Resources section below)? This can be used to assess the line thickness that the child responds to and the visual fields.
• Which quadrant does the child respond in, do they respond to targets in the central field of vision?
• How long does it take to observe a response?
• What detail can be seen and responded to?

Important considerations

Optimum lighting

Some children are very sensitive to light or glare, while some children with profound CVI respond better in low lighting conditions.

Distractions

Objects in bold plain, preferred colours should always be used initially. Patterns and cluttered environments make visual information more difficult to process. E.g. presenting an object against patterned clothing or signing in front of a patterned background makes it harder to process and thus respond to. I carry a dark, plain T-shirt when working with children with complex needs. Work in a space that is quiet and uncluttered, as noise inevitably distracts the child.

Comfort

What time of day is it? Is the child feeling tired or unwell? Are they as comfortable as possible and in a position where they can best view what you would like them to respond to? This is very important if a child has a visual field impairment or nystagmus, where they need to be able to use their “null point” to achieve their best possible vision. A child who is uncomfortable will not be able to put their efforts into visual attention.

Glasses and make up

Bright lipstick emphasises the mouth and eye makeup and glasses help some children to see your face more easily. You decide if this is an option for you! One child always reaches for my bold framed glasses and shows little interest when I am not wearing them. These factors may all influence a child’s ability to respond.

Time to respond

Focus on one object at a time. Give time for the child to process and then even more time to respond. Sometimes, responses may take several minutes to occur, and intervening before enough time has passed can prevent children from processing and developing their own responses. Allowing more initial time can improve overall processing and response outcomes over a long period of time.

Presenting the object

Consider the implications of visual field impairments especially if you are placing objects on trays attached to chairs. A child with a lower field impairment may not see items placed close by them on a tray but may be able to see them propped up further back on the tray using a wedge, or if the tray is lifted until seen. Interpret responses carefully. Is the child really seeing the object on the tray or responding to someone moving in towards them from the front when they are placing it?

Apps to encourage or assess visual response

There are helpful apps and technology to use but don’t be tempted to do too much at once. The best apps allow the speed and colours of any activity to be modified. Many children need a degree of movement to engage with a stimulus, but on screen it must be slow enough to give time to respond. You can readjust the speed once the child has seen the target or activity frequently and long enough to recognise it and respond more quickly. Find what motivates and repeat and repeat. You may find the repetition boring, but it allows the child’s brain to recognise, “see”, engage and learn.

Colour tents

Patient use of a colour tent may enable children who have the most profound cerebral visual impairment to respond. Suzanne Little has worked extensively with colour tents with young people who have complex needs. The tents help learners to block out all distraction and begin to engage with their world. “Each child with CVI needs a structured, individual approach”.

I have worked with a child who was previously showing extremely limited responses. Now when placed comfortably under her preferred fabric she is beginning to respond and interact, reaching up to the tent above her and vocalising happily.

Large pieces of lining fabric, some fluorescent, are very portable and can be cheaply bought via eBay. For young children or babies, a small pop-up tent can work just as well, if pattern is eliminated by tacking on plain fabric. Success may take many sessions and all the factors which may affect visual response, need to be considered.

Each child with CVI needs a structured, individual approach. Painstakingly taking account of the factors that may affect their responses will help them to achieve their visual potential. By understanding more about how the visual system works and changing mainstream perception of “vision”, we can help to transform the lives of those affected by CVI and their families.

CVI specific organisations

Janet Harwood is a QTVI and is a staff writer for the CVI (Cerebral Visual Impairment) Society.

For more information about cerebral vision impairment visit the CVI Society website.

CVI Scotland also provides resources and information around cerebral vision impairments: CVI Scotland

Additional Resources

Puppet faces

Puppet faces are six hand-held puppets that can be twirled between finger and thumb. They are not toys and should be used by adults to assess visual awareness and a baseline indication of field of vision. The back of the puppet is not easily seen against a dark background but it “pops” into view when twirled round. Another half twirl and it disappears again! Available from Beesneez. 

Visual assessment and vision stimulation apps 

A huge number of apps are available, many for free, but one size doesn’t fit all. Remember that for children with CVI “less is more”.

Explore some of the options on the Inclusive Technology website and the Wonder Baby website.