Transcript Visual Impairment Following Stroke

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CLINICAL DEFINITION
‘A rapidly developing episode of focal or
global dysfunction, lasting longer than 24
hours or leading to death, and of presumed
vascular origin.’ (Macintosh, C; 2003)
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Brain damage due to lack of oxygen and
nutrients to the brain as a result of burst
blood vessels or a blood clot.
(The World Health Organisation – WHO)
Leslie Ritter and Bruce Coull, 2011 (The University of Arizona)
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85% ischaemic:
Cerebral artery blockage (cerebral
thrombosis)
Cerebral Infarction
Atheroma build up in intra and
extracranial arteries
Embolus – travelling blockage
15% intracerebral or arachnoid
haemorrhage
75%
Cerebral
Infarctions
10%
}
15%
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Most common cause of disability
Third most common cause of death
150,000 sufferers per year on average
Age 65+
Effects dependent on area of brain
affected
All different in and of variable severity
Effects short and long term
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Walking
Speech and or language
Mental processes – cognition
Swallowing
Paralysis
Eyesight
Visual field loss
 Blurring of vision
 Reduced vision
 Nystagmus
 Diplopia
 Moving images – oscillopsia
 Visual Neglect
 Difficulty judging depth and movement
 Photosensitivity
 Hallucinations
 Agnosia – recognition difficulties
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Ptosis
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Anisocoria
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OCULAR MOTILITY DISORDERS
Diplopia
Gaze palsy
Oscillopsia
Cranial Nerve Palsies – isolated or
combined
Supranuclear gaze palsies
Skew deviation
INO
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Medial rectus, superior rectus, inferior rectus, inferior
oblique, levator palpebrae superioris, pupillary
sphincter
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Superior Oblique muscle
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Lateral Rectus muscle
All ocular muscles
 Glossopharyngeal nerve (for swallowing)
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Damage to cortical control of eye
movements
 Severe stroke – difficulty looking away
from lesion
 Can have deviation of eyes towards lesion
site.
 Gaze palsies – poor prognosis
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Common effect of stroke
 Oxford Audit – 55% of patients VAs <6/12
more than 2 wks post stroke
 Many patients found to have improvement
after 1-2 wks
 Ensure patient has glasses if worn
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Demonstrate vision test
Speak slow
Repeat yourself where necessary
Uniocular VAs
Assess reading ability – can identify
problems e.g. – field loss, neglect,
impaired eye movements
Type of field loss dependent on location of
stroke
 Can affect patients in daily life activities
and driving
 Many patients unaware of field loss
 Right sided defects most common
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Complete Left visual
field loss
Binasal hemianopia
Bitemporal
hemianopia
Right homonymous
hemianopia
Right homonymous
superior
quadrantinopia
Incongruous right
homonymous inferior
quadrantinopia
Right
homonymous
hemianopia with
macular sparing
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Homonymous hemianopia (most common)
Stroke of middle cerebral artery or posterior
cerebral artery
Affects optic radiations or visual cortex
Post stroke – often homonymous and
congruous
Macula sparing = occipital cortex
Riddoch phenomenon: Complete
homonymous hemianopia to immobile
objects but detection of moving objects
maintained.
Can be associated with visual neglect
 Lesion – optic radiation damage usually in
right hemisphere.
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Most disruptive and common visuo-spatial problem
after right sided stroke
Ignoring everything in a particular region of space
More common in right sided stroke
Limits rehab. Associated with poor functional
recovery
Can affect all distances.
Examples:
- only eating from one side of plate
- shaving one side of the face
- only drawing half a picture
Can be associated with visual field defect
Field Defect
Neglect
Make effort to achieve full
pursuit movements
Poor and incomplete
pursuit
Searching saccades after
target disappears
No effort to find target
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Albert test
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Neglect – Lines missed on one side of the page.
Tests for neglect invikve cancellation, copying
and drawing to prove that patients miss half of
the picture and or the text
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Balloon Test
Test A – look for and cross through 22
balloons amongst 202 balloons and circles
(targets popping out)
Test B – finding and crossing through 10
circles within 3 minutes (serial searching)
Serial search more impaired than parallel
search in visual neglect
Test B requires more attention – missing
more on test B eliminates possibility of field
defect
Bilateral vision loss
 Damage to striate cortex
 Posterior cerebral artery infarction due to
embolism
 Not all patients aware
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Charles Bonnet syndrome
 Lack of sensory impulses to visual cortex
 Differentiate hallucinations from diplopia
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Cognitive
 Poor recognition
 No problems with vision and perception
 3 types:
- Visual Object Agnosia
- Prosopagnosia
- Colour Agnosia
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Ensure patient has correct glasses and
wearing correct glasses for viewing
distance
Ensure prescription up to date
Re-refraction may be necessary
Low vision aid – magnifiers etc
Compensatory head postures
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Coloured markers on one
side of page
Underlining text
Typoscope (strip of card
with a section removed to
imitate a window)
Following text with the
finger
Turning the page – to read
vertically or upside down
depending on type of field
loss
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Fresnel prisms
Place prism on half of lens on side of
hemianopia facing in direction of field defect:
Base out prism on left half of left lens in left
sided hemianopia
Displacing image in missing area to one side
to make patient aware of it
Increase scanning skills
Prism adaptation training (Keane et al
2006)
Visual stimulation of the visual field border
area (Bergsma and Van der Wildt 2009)
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Scanning training
Limb activated treatment
Sustained attention training
Fresnel prisms – base away from
neglected side to encourage patient to
look in neglected area
Monocular occlusion of eye on side of
lesion – patient forced to look in neglected
area of vision
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Visual Field Loss Following Stroke or Head Injury (BIOS)
Bergsma DP, Van Der Wildt G. Visual Training of Cerebral Blindness
Patients Gradually Enlarges the Visual Field. British Journal of
Ophthalmology 2010; 94: 88-96
Keane S, Turner C, Sherrington C, Beard JR. Use of Fresnel Prism Glasses
to Treat Stroke Patients with Hemispatial Neglect. Archives of Physical
Medical Rehabilitation 2006; 87: 1668-1672
Lee AW, Daly A, Chen CS. Visual Field Defects after Stroke. Australian
Family Physician 2010; 39(7): 499-503
Macintosh C. Stroke re-visited: visual problems following stroke and
their effect on rehabilitation. British Orthoptic Journal 2003; 60: 10 – 14
Op de Beeck H, Haushofer J, Kanwisher NG. Interpreting fMRI data: maps,
modules and dimensions. Nature Reviews Neuroscience 2008; 9: 123-135
Townend BS, Sturm JW, Petsoglou C, O’Leary B, Whyte S, Crimmins D.
Perimetric Homonymous Visual Field Loss Post Stroke. Journal of
Clinical Neuroscience 2007; 14(8): 754-756
www.RNIB.org.uk