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of Vision

Visual Elements

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What is `functional vision'?

It is the use of vision for particular purposes. Functional visual skills are required to carry out everyday activities.

Everyday activities

Why assess functional vision?

The differences in how people use vision are not always related to measures of distance visual acuity or near vision. A person may have very poor vision, not good enough for detailed work such as weaving, carving or reading but may be able to see and avoid objects so that he can move around safely. Functional vision may be improved with training. Many people can learn to make better use of their low vision and can function efficiently with only small amounts of visual information. Objects and print can be recognised when they are blurry or when only parts of them can be seen

A person with limited distance vision may have difficulties:
  • learning by imitation
  • understanding nonverbal communication
  • integrating senses (e.g. visual/auditory, visual/tactual, visual/olfactory, visual/gustatory)
  • with independent mobility (e.g. avoiding obstacles and detecting moving vehicles, bicycles or animals)
  • recognising people, objects or actions

A person with poor near vision may have difficulties:
  • with personal care and hygiene
  • preparing food and eating
  • making and taking care of clothes
  • weaving, carving, etc.
  • reading

A person with restricted visual fields may have difficulties:
  • with general functioning in poor light
  • finding objects
  • with independent mobility

To understand the specific implications of low vision for each person it is necessary to

  • determine the activities normally done by the person with low vision and other people in the same community and what visual skills are required to carry these out. This may be at school, in the village, or at work. The person should be assessed in a place appropriate for those tasks.
  • analyse the visual elements of a task so that the task can be modified and the environment adapted to the special equipment used

  • observe the visual environment and assess/observe the person under different environmental conditions. Vary aspects of the environment also, e.g. distance from the task, lighting, contrast, colour and time allowed

  • determine which sense is the most efficient for a particular task. For example, vision, enhanced vision, auditory, tactual, or some combination of these senses.
everyday activities requiring vision

What is obtained from an assessment of functional vision?

The first part of the assessment is the observation of the effects of low vision. The second part is the assessment of visual skills used for functional vision.

The results give an understanding of the effects of low vision for each person and how vision is used. The results show the importance of distance, size, contrast and light, for each person. Therefore, the skills that need to be trained can be identified in order to plan a training program.

What is done with the results?

The results from the assessment show how vision is being used and which visual skills have been learnt. The skills that need to be trained can be identified in order to plan a training program. The information from the assessment should be discussed with the person with low vision, his family and others such as teachers.

For more information see the Functional Assessment chapter


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