Navigation and maintaining safety
Activity 8: Navigation and maintaining safety, using a guide dog or other aid if normally used (Activity 8 is detailed at this point to reflect the structure of the ESA 85 and LiMA application)
Descriptors
V(a) Unable to navigate around familiar surroundings, without being accompanied
by another person, due to sensory impairment.
V(b) Cannot safely complete a potentially hazardous task such as crossing the
road, without being accompanied by another person, due to sensory impairment.
V(c) Unable to navigate around unfamiliar surroundings, without being
accompanied by another person, due to sensory impairment.
V (d) None of the above applyScopeThis activity not only relates to visual acuity (central vision and focus) and visual
fields (peripheral vision) but takes into account the persons ability to adapt to
their condition. The person’s confidence and training must be taken into account.
Within the modern workplace, many adaptations can be made to accommodate
those with visual impairment.
Within the workplace, the key issue is the individual’s ability to navigate
and maintain safety in their environment.
The environment must be taken into account. Those who are able to navigate in
familiar surroundings but need the support of another person in an unfamiliar
environment, will have a greater level of disability than those who have adapted
to navigating in any area, whether familiar or unfamiliar.
The concept of safety awareness and the person’s ability to safely negotiate
hazards must be considered. This is an important issue in a workplace as
provision of a companion throughout the working day to ensure safety may be
considered an excessive adaptation for an employer to make.
The clinical history must be considered. The duration and speed of progression of
visual loss is likely to impact on an individual’s ability to adapt to navigation and
safely negotiate hazards. For example, someone who has had sudden complete
loss of vision very recently, perhaps as a result of trauma, is less likely to have
adapted quickly than someone with congenital visual restriction or a slower
progression of visual loss. Other medical conditions may have to be considered
to asses the individuals likely ability to adapt – e.g. those with cognitive
impairment may have more difficulty adapting to a visual impairment.
The person’s ability must be considered in the context of using any aids such as
spectacles, a white stick or guide dog they normally use. As a guide dog is not
universally available/suitable for every person, the use of a guide dog must only
be considered if the person has a guide dog. The use of GPS devices would not
be considered in this area.
The level of visual restriction is likely to impact on the person’s ability to navigate.
Visual field restriction is also important in maintaining awareness of hazard, but
again, the ability to adapt should be considered – e.g. turning the head to look for
traffic/other hazards.
Any restriction identified must relate primarily to a sensory problem, and not
cognitive issues as these are considered elsewhere.
Normal vision is taken as visual acuity of 6/6 at a distance of 6 metres from the
Snellen chart. To hold a class 1 driving licence in the UK, acuity of 6/10 on the
Snellen chart is required. To have problems in navigation, it would be expected
that the person would have a severe level of sight impairment. It is likely the
person will be registered as sight impaired or severely sight impaired .A person
registered as sight impaired or severely sight impaired will be given a certificate
of visual impairment (CVI). If the claimant brings a CVI with them to the
examination, the HCP must review the information on this and take it into
account in their justification. A copy should be made with the claimant’s
permission for inclusion in the file for the DM. Registration of a person as
severely sight impaired or sight impaired is the role of the consultant
ophthalmologist. This can be a complex procedure but some examples are
provided below.
People with acuity below 3/60 on the Snellen chart would be considered as
severely sight impaired. People with acuity of 3/60 but less than 6/60 with
significant visual field restriction may also be registered as severely sight
impaired. For sight impairment there is no formal definition, however those with
acuity of 3/60 to 6/60 with a full visual field may be registered as sight impaired.
Those who have a gross contraction of the visual field and vision of 6/18 or even
better may also be registered as sight impaired. Further details of sight/severe
sight impairment registration can be found at:
www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/documents/digitalasset/dh_078294.pdf
Copies of the CVI can be reviewed at:
www.rcophth.ac.uk/standards/cviIt may be useful to consider DVLA driving requirements in relation to functional
ability. In order to have a class 2 driving licence in the UK, a full binocular field of
vision is required. For a normal class 1 driving licence in the UK, specific
standards are also required and, for example, someone with a homonymous
hemianopia or bitemporal defect would not be allowed to hold a licence. Further
information on driving standards can be obtained on the DVLA website:
www.dvla.gov.uk. The LiMA repository contains extensive useful information on
assessment of vision and visual fields and may be referred to.
Details of Activities of daily livingConsider activities such as:
Driving – both from the visual acuity and visual field point of view
Ability to get around indoors
History of falls or accidents
Ability to use public transport- get on and off buses unassisted and read
the bus name and number
Mobilising independently outdoors
Going to a supermarket
Reading newspapers or magazines
Maintaining safety in the kitchen, ability to cook meals
Getting in and out of a bath
Caring for children
Observed behaviour
Ask the claimant how they got to the examination centre, and how they found
their way around the centre. Note whether the claimant needed to be
accompanied by another person.
Observe movement when navigating obstacles- do they rotate their neck more to
adjust for reduced visual fields?
Note any observed ability to manipulate belts and buttons.
Observe whether the claimant manages to read their medication labels or repeat
prescription sheet.
ExaminationRecord the aided binocular vision, and explain the significance of this to the
Decision Maker.
If the claimant forgets their spectacles but there is evidence from the typical day
activities and behaviour observed that there is no significant disability with vision,
then this should be reflected in your descriptor choice. In these cases or in cases
where the VA is poor but you think it could improve with correction measure it
using a pinhole. Only in exceptional circumstances should a claimant be recalled
to have their eyesight tested with spectacles worn.
Near vision should be recorded using a near vision chart. N8 print is the
equivalent of normal newsprint. HCPs should ensure that they use a near vision
testing chart with N16 print to accurately assess ability to read 16 point print.
Visual field testingWhere there is a history of any visual field problem or where the practitioner at
assessment feels there may be a visual field problem, visual fields must be
tested.
Visual field testing can be a complex procedure requiring sophisticated
equipment to aid diagnosis or to assess minor defects in the visual fields.
Minor defects in visual fields will rarely result in significant functional problems.
Therefore for the purposes of disability analysis, the traditional method of visual
field examination by the “confrontation method” detailed below is adequate to
detect gross defects in the visual fields that may be of functional relevance. If the
person has a CVI, details of visual field restriction may also be detailed there.
A structured approach for performing visual field testing by the “confrontation
method” is outlined below:
Ensure you have a piece of card for the claimant to cover up one eye
Sit 60cm from the claimant and ask them to look directly into your eyes
and keep looking straight at your face
Ask the claimant to cover one eye with the card provided
Check there is no central defect by ensuring they can see your full face
Stretch both arms out in a plane equidistant between you and the claimant
and at the outermost periphery of your vision
Move the index and middle fingers on one hand and confirm the claimant
can see your fingers moving and ask the claimant which hand is moving
Move your hands to different positions to check the superior, inferior, nasal
and temporal fields in order. You may wish to change the fingers being
moved to ensure accuracy of response.
For the purposes of the LCW/LCWRA, you should consider any visual field
loss in the context of whether or not it is likely to impact on the person’s ability
to safely navigate. This should be in considered with visual acuity and the
typical day and any information obtained from a CVI brought by the claimant.
You must provide the DM with a detailed justification of your choice of
descriptor.