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Finding out about functional vision AAC SIG: Making Sense of AAC November 4th 2014.

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Presentation on theme: "Finding out about functional vision AAC SIG: Making Sense of AAC November 4th 2014."— Presentation transcript:

1 Finding out about functional vision AAC SIG: Making Sense of AAC November 4th 2014

2 Judy Bell Independent consultant in visual impairment & complex needs

3 What the session will cover Brief considerations of: The nature of functional vision The differences between functional & clinical vision assessment Who might carry out functional vision assessment The aspects of functional vision that will impact on the choice and use of AAC How these aspects might be assessed

4 The nature of functional vision

5 Functional Vision Functional vision is the way an individual uses his or her sight in everyday situations

6 Functional Vision An individual’s level of functional vision will vary according to both internal (e.g. health, hunger, tiredness etc.) and external conditions (e.g. location, lighting etc.)

7 Functional and clinical vision assessment

8 Functional vision assessment Assessment is via observation of structured activities and interaction in everyday situations Assessment takes place in an environment which is familiar to the individual

9 Clinical assessment of vision Direct clinical examinations are undertaken Standardised test material is used Assessment is usually within a clinical setting such as an optometrist’s examining room or hospital clinic

10 Individuals involved in functional vision assessment Often co-ordinated by a QTVI or QTMSI although anyone who knows and works with the individual can undertake such an assessment The observations of those who know the child well contribute to the assessment

11 Practitioners who may be involved in clinical vision assessment Ophthalmologist (eye doctor) Optometrist (ophthalmic optician) Orthoptist (specialist in binocular vision & eye movements) Paediatrician School nurse Usually these practitioners are not familiar to the individual

12 Aspects covered by clinical vision assessment Appearance & health of eyes Refraction Eye movements Alignment of gaze & binocular vision Visual acuity (distance) Visual acuity (near) Visual field Contrast sensitivity Colour vision

13 Aspects covered by clinical vision assessment Visual acuity (distance)

14 Visual acuity distance: Snellen Fraction-like figure, e.g. 6/6, 6/12, 6/18, 6/24, 6/36, 6/60 Bottom figure refers to the distance at which an individual with normal sight would be able to perceive image clearly Top figure refers to distance at which the person being tested is able to perceive the image clearly

15 Visual acuity distance: logMAR Using the logMAR system, visual acuity is recorded as a decimal figure 0.0 to equates to Snellen 6/ equates to Snellen 6/ equates to Snellen 6/ equates to Snellen 6/6

16 Clinical vision: Assessment to threshold Clinical vision assessment tests to the threshold at which an individual is able to see clearly No individual will willingly perform to visual threshold 100% of the time

17 Functional vision: Assessment of typical use of vision Functional assessment identifies how an individual uses his or sight in identified situations Functional vision assessment provides a picture of an individual’s ‘typical’ use of vision in everyday situations

18 Clinical and Functional Assessment Functional assessment should be ongoing Clinical assessment needs to be undertaken on a regular basis

19 Clinical and Functional Assessment Together, the clinical and functional assessment of vision provide a full picture of the visual needs of an individual Both will be required in order to determine the nature of AAC to be used.

20 Aspects of functional vision that will impact on the choice and use of AAC

21 AAC: Aspects of functional vision Initial considerations: Willingness/reluctance to use vision Preferred sensory channel(s) – single or multi-channel Variability of vision

22 AAC: Aspects of functional vision Near vision will be main, but not only, concern If signing is used, an assessment of distance vision will be important in order to establish optimal distances Difficulties with distance vision will affect incidental learning & subjects available for communication

23 AAC: Aspects of functional vision Near vision – consider preferred Lighting: –Strength –Type (natural, colour, LED, overhead, backlighting, task etc.)

24 AAC: Aspects of functional vision Near vision – consider preferred Size of stimulus (bigger not always better) Distance of stimulus (function of size) Position of stimulus (direction and plane)

25 AAC: Aspects of functional vision Near vision – consider preferred Contrast Colour Tone

26 AAC: Aspects of functional vision Colour, tone & contrast

27 Colours of a similar tone – poor contrast Photocopy Colour, tone & contrast

28 Colours with tonal contrast Photocopy Colour, tone & contrast

29 AAC: Aspects of functional vision Near vision - consider Tracking skills: direction, speed, midline Scanning skills: direction, speed, midline, coverage Shift of attention from one stimulus to another: direction, speed, midline, coverage

30 AAC: Aspects of functional vision Near vision - consider Visually directed reach and grasp –Locate, look & reach or…. –Locate, look away & reach

31 AAC: Aspects of functional vision Near vision - consider Clutter – stimulus & stimulus/background Visual distraction

32 AAC: Aspects of functional vision Clutter – stimulus & stimulus/background: Visual distraction

33 AAC: Aspects of functional vision Clutter – stimulus & stimulus/background: Visual distraction

34 AAC: Aspects of functional vision Clutter – stimulus & stimulus/background: Visual distraction

35 AAC: Aspects of functional vision Near vision - consider Time taken for visual processing & response

36 AAC: Aspects of functional vision Near vision – consider preferred Movement of stimulus –Constant –Intermittent –Still Sound production related to stimulus –Nature –Duration – intermittent or constant Nature of images –Photographs or drawings

37 How aspects of functional vision might be assessed

38 Functional vision assessment Observation in normal environment Observation of structured intervention and response Interview with those who know individual in different settings

39 Functional vision assessment Various schedules and profiles JB 2009 – Functional vision observations & assessment sheets – downloadable from website

40 Contact Judy Bell


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