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Assessing Visual Fields - Where is the Useable Vision?

Visual Responses With Movement

  • Find an object you know the person responds to visually (a favourite toy for example), but not one that makes a noise (to ensure the response is not related to the sound).
  • Think of a clock face, and without them noticing, place the object on the floor, approximately 30cm in front of the person (six o'clock, where your feet were in Exercise 2, above)
  • Slowly, bring the object up to the person's eye level, still approximately 30cm in front of them.
  • At what point did they see the object (if at all)?
  • Mark it on the diagram
  • You may, as a development, if a lower field deficit has been found, want to move up from 7 on the clock, then again up from 5, because in some, the lower field impairment extends further down on one side than the other, explaining tripping with one foot but not the other.

If the object is a favourite toy, it is possible that the person may start searching for it, which would make further attempts to assess the visual field at that time difficult.

This is the first of two assessments; you should not try to complete both visual field diagrams in a single session, they need to be built up over time, in different environments. All these assessments are designed to be ongoing and forever evolving with the greater knowledge you build up about the person's visual world.

Over time, when you are out and about, walking, playing or getting ready for bed repeat the asessments. It doesn't have to be the same object, but it does have to be something the person has previously clearly demonstrated they can see.

Some visual field impairments can be assessed in quarters, and whilst assessing you may want to consider the quadrants that form the quarter sections between

  • 12 and 3 o'clock
  • 3 and 6 o'clock
  • 6 and 9 o'clock
  • 9 and 12 o'clock

Notes:
Who Where When What How Why

Notes let you look back at what you found - where possible make notes about the environment when the visual responses do and do not occur, for example:

  • Noisy / quiet
  • Against an uncluttered background
  • Against a cluttered background (which is more difficult to test, but is 'real life')
  • Person is tired
  • Person is stressed / anxious
  • The environment is busy (describe)
  • Did the person turn their body or head or both
  • Did they reach out
  • Could they cooperate?

And anything else you think may or may not be relevant, you might be surprised to find out what different factors may have an effect on the person's visual responses, for example when they are eating, or if a particular person is present (the excitement of someone they like, or the stress of anticipation of someone they dislike).

Non-Verbal People

Depending on their abilities, the following reactions may show a response in a visual field. To be more confident the tests need to be repeated, at different times and in different environments.

  • Stilling - stopping what they are doing and concentrating, this may not involve directly 'looking' at the object, but using peripheral vision to focus on what they are interested in instead.
  • Reaching out - either leaning over, reaching with their hand
  • Making a noise, for example a noise that you know means they are happy
  • Moving their head, again this might not obviously look like they are directly looking at the object
  • Moving their body
  • A head turn
  • A body turn

Make a note of what the person did to make you think they saw the image in different parts of the visual field. Are the responses different?

For example in some areas the person may still, and in other areas become more animated, or excited, make noises or try to reach. This may be an indication of a stronger visual response in different areas of the visual field.

Visual Responses Without Movement

You need to be careful, because you are looking for a visual response to an object that is not moving. It can still be a favourite toy, but if you move it to a different part of the visual field, that act will be creating movement (although can be recorded on the first diagram of course).

It is also tricky because the person may be creating their own movement, by for example rocking, or turning their head from left to right. This all needs to be noted. Over time, in everyday settings, just note the areas the person shows they can find objects, and then think about placing items in the areas both inside the sighted areas and outside of the sighted areas, and see if they can still find them. Over time, areas with regular strong visual responses should be confirmed, and areas with irregular, or no visual responses noted.

Look to complete every section of both diagrams, with extra notes.

The detail in the notes is key: To understanding the person's visual world, you have to understand the person, not just their visual brain.

To demonstrate this let us re-visit Mary and Connor. Here is a reminder Mary's visual field from the previous section.

From the middle picture, of what Mary's Brain Sees (above) we would expect Mary's visual field diagram to look a bit like thisFrom the middle picture, of what Mary's Brain Sees (above) we would expect Mary's visual field diagram to look a bit like this

Actually, it looks more like this, but there are pages of notes to supplement itActually, it looks more like this, but there are pages of notes to supplement it

Mary does sometimes respond on her right side, but only when there is movement. Mary doesn't always respond on parts of her left side, because she also has simultanagnosia.

Here's a reminder of Connor's visual field from the previous section:

Connor has a lower visual field impairment and doesn't respond to anything visually in the bottom half of his lower visual field. In addition, the working part of Connor's lower visual field has poorer clarity than his upper visual field.Connor has a lower visual field impairment and doesn't respond to anything visually in the bottom half of his lower visual field. In addition, the working part of Connor's lower visual field has poorer clarity than his upper visual field.

From what we have been told, we might expect Connor's visual field diagram to look like thisFrom what we have been told, we might expect Connor's visual field diagram to look like this

But actually it is more like this, again with many notesBut actually it is more like this, again with many notes

Mary and Connor's visual worlds demonstrate the multiple filters of CVI and how they impact upon one another, and we shall follow their path, to help explain.

Get used to constantly checking, testing and thinking about the impact of the visual fields; you will become very familiar with the areas with stronger visual responses. You may sometimes be surprised when you get a visual response in an area previously unresponsive. It is important to encourage search in the person's sighted and non-sighted fields, to help develop exploration.

You need to note it all down, it's so easy to forget details, and it's the details that can tell us everything.

Don't wait to fully complete this section before starting the other assessments, as stated, it should be an ongoing assessment.

"At first I was quite deliberately testing Connor's visual field, just doing everyday things, like giving him a toy in the car, and noting where he registered it, and how. Over time it became a less conscious task, and I sort of just tuned into what he was looking at and where, if that makes any sense? I realised than in his very lower visual field, he not only never saw things (shown by tripping over things), but he also didn't make memories, so he tripped over the same thing over and over again. I also noticed that whilst he was regularly visually responsive in his upper-lower, middle and upper visual fields, that there was this optimum band in the middle where he seemed to see best. It seems to be as strong at the sides as the middle, and he seems to bring things to this band to look at them. Within this band his visual responses are quicker.


It's really useful to know, because if we want to help him focus on something that may be visually challenging, like a picture book, we know the best place to put it for him to see it."

Connor's optimal visual band, as discovered by his motherConnor's optimal visual band, as discovered by his mother

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