Wednesday, 30 November 2011

How do I know if my child has a cortical visual impairment? Part Two

Those who study CVI have identified a number of different types of visual behaviour that combined together can point to a difficulty seeing rooted in the cerebral cortex rather than the eye globe. In my experience many of these are frequently combined with children who have this diagnosis. Here are a few of them; there are others.

Look, turn and reach
When initiating an engagement the CVI child tends to look at an object first, then turn their head away and finally reach out their hand to grab the object. Normally this sequence of actions would be integrated into one action, coordinating vision and body movement. But it seems that the child cannot do actions in a coordinated way; instead they simplify and break down the actions.

Aversion to novelty
Normally children are interested in a new object or toy and will reach for it to explore it as soon as it presents itself. The CVI child behaves differently. If something is new or unfamiliar they initially show no interest and in fact may deliberately avoid it.

Fluctuating vision
It is characteristic that a CVI child appears to see better one day than the next, in fact their vision can fluctuate from moment to moment. One minute they seem to be looking and the next you cannot get them to look at all.

Light gazing
CVI children characteristically like to gaze at bright lights. They may be ceiling lights, window lights, desk lamps or light emitting toys. Indeed one way to gain the child’s attention is to use a flashing light. Lights can be a distraction when you are trying to maintain the child’s attention on an object and there is a bright window light nearby or and strong ceiling light above.

Delayed response time
Most young children react quickly to a response that gets their attention, but the CVI child will frequently take significantly longer to generate a response. This can be frustrating for parents and workers who sometimes step in too quickly to assist the child.

Failure to fix and follow
If the eyes are known to be normal then a difficulty in fixing on a visual target and following the moving target should flag up a serious concern.  In this case it is likely that there is something wrong in the visual processing areas of the brain.

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