Visuoperceptual difficulties in dementia
This factsheet considers some specific visual perception difficulties that
people with dementia can have, and possible ways of helping them.
Understanding potential perceptual problems and intervening with appropriate
help, support and reassurance can greatly assist people with dementia to feel
safe in their changing perceived reality.
People with dementia can experience a number of such difficulties due to
normal ageing, eye conditions, and sometimes from additional damage
caused by specific types of dementia.
Vision difficulties can result in a variety of 'visual mistakes'. They can cause a
person with dementia to misinterpret their environment and what is in it. The
consequences of such difficulties can be more severe for people with
dementia than for people without, since they may not know (or remember)
that they are making 'visual mistakes', or be rational or able to 'test reality'
accurately. They may also have difficulty explaining what they have seen.
Visual perception difficulties have been reported for a number of dementias
including Alzheimer's disease, dementia related to Parkinson's disease, Lewy
body dementia, and vascular dementia. Of the various types of dementia, the
visual difficulties in Alzheimer's disease have been most studied to date.
Visual perception is complex since, whether people have good vision or not,
they try to interpret and understand what they see. Sometimes trying to
understand what was 'poorly seen' involves making a 'best guess' at what was
seen. If what we perceive seems real to us, it can directly affect our
behaviour.
Normal age-related changes in vision
Visual changes resulting from normal ageing can include reduced visual
sharpness, an increase in the amount of light needed to see, and many
others. Most people have regular sight tests and adjust automatically to their
changing vision as they get older. They can use glasses, accurately problemsolve, or learn to compensate for visual changes. However, people with
dementia, increasingly, may not be able to do this.
Illnesses, drugs and medications can affect vision
As well as the effects of normal ageing on the visual system, a number of
visual disorders are commonly associated with ageing, including cataracts
and complications from diabetes. These can all result in changes such as
blurring, hallucinations and blindness.
Use of alcohol and other recreational drugs can also affect vision, as can
withdrawal from them. Sometimes medications can cause or contribute to
visual difficulties. A surprising number of medications commonly taken by
older people can have visual side-effects. They include some drugs from the
following categories: cardiovascular, non steroidal anti-inflammatory,
antibiotics, anti-Parkinson, and even eye medications.
Additional visual difficulties in some types of dementia
There can also be additional visual difficulties in dementia related to
Parkinson's disease and Lewy body dementia. In vascular dementia, if strokes
occur, a wide range of visual perception difficulties, including hallucinations,
can result. Importantly, changes in vision from strokes may not be noticed by
an individual.
Currently, most is known about visual difficulties resulting from Alzheimer's
disease. Some noticeable consequences of such problems include difficulties
with assembling puzzles, reading books, or watching TV shows with rapidly
moving images.
Less obvious difficulties may involve the ability to:
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play board games
keep handwriting in horizontal lines
find objects readily (even though they may be in front of a person)
copy images accurately
walk or move confidently.
Visual difficulties can affect many aspects of a person's daily functioning. If
people with dementia are living in their own home with carers who are helping
them, the real extent of their visual difficulties may not be apparent until they
experience a change in environment, like going out shopping, on an outing, or
on holiday.
Visual difficulties and 'perceived obstacles' can make a person more fearful of
falling, and slow down their movements while they try to walk safely. If carers
and companions understand this, they can try to anticipate situations which
will likely pose perceptual difficulties, help explain what is being encountered,
offer their arm for support, offer encouragement, and slow down their own
movements around a person with dementia.
Interventions for visual perception difficulties
The increased understanding of visual mistakes is generating new ideas for
assisting people with dementia.
Careful attention to eye care and visual health
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Check that any glasses worn are clean and that the prescription is
correct (for more advanced dementia, this may require use of special
non-verbal tests as for people with learning difficulties)
Arrange for regular eye checks
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Encourage the person to wear glasses if they need them. Glasses will
improve the sharpness of what is being seen; however, glasses cannot
correct difficulties resulting from other types of damage
If cataracts are the cause of, or contributing to, poor sight, talk to a GP
about how to have them treated.
Environmental adaptations
Aiding specific visual functions can help people with dementia. The first thing
to do is to improve lighting levels. It has been estimated that more than half of
British homes do not have enough lighting even for ordinary visual purposes.
Improved lighting has been found to be instrumental in preventing falls, and
also in reducing visual hallucinations.
Deliberate use of colour cues can also help significantly. For example, one
study with people with advanced Alzheimer's disease showed that changing
to highly visible red cups and plates led to a 25 per cent increase in food
intake and an 84 per cent increase in liquid consumption. Brightly coloured
toilet doors have also been used successfully in a variety of care settings to
help people with dementia find the toilet independently, and more readily.
High contrast toilet seats (compared to the colour of the toilet fixtures and
walls) can make it easier to locate them. If a person needs handrails choose
extra-long ones so that they are as conspicuous as possible (without the
person having to turn their head to look for them).
Some tips for minimising visual perception problems
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Provide good, even lighting (people resist going near dark areas in
corridors and rooms)
Try to eliminate shadows
Minimise busy patterns on walls and flooring
Use of non-shiny, light-coloured flooring will reflect light upwards and
enhance overall ambient light levels
Remove or replace mirrors and shiny surfaces if they are problematic
Highlight important object and visual cues (signposting/orientation
points)
Camouflage objects that you do not want to emphasise (e.g. light
switches or doors that people with dementia shouldn't use)
Minimise 'visual obstacles/barriers' such as changes in floor surfaces
or patterns, to assist independent walking
Choose activities to match the person's visual abilities.