Transcript Cortical Visual Impairment and Blindness, Functional Implications

Cortical Visual Impairment and
Blindness
Functional Implications and
Rehabilitation
Kia B. Eldred, OD, FAAO
Diplomate in Low Vision
Michael E. DeBakey VAMC
and University of Houston
College of Optometry
Course Objectives
• Participants will be able to define Cortical
Blindness and Visual Impairment and identify the
different types of presentation of acquired vs.
congenital.
• Participants will recognize the clinical findings
and functional implications of cortical vision loss,
as well as strategies to enhance vision.
• Learners will understand less commonly seen
cortical visual changes. The importance of
rehabilitation and education will be emphasized
for this population of patients.
Definition of Cortical Blindness and Visual
Impairment Congenital and
Acquired
• Blindness or Visual Impairment (CVI) due to
bilateral damage to the occipital cortex (Hoyt,
2003).
• The absence or reduction of vision in either
eye while still maintaining a normal pupillary
response to light and a normal ocular
examination.
• It can occur both congenitally and it can be
acquired, with many fewer cases acquired.
Vision Loss in Children
in the U.S.
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Cortical Visual Impairment -22%
Retinopathy of Prematurity – 14%
Optic Nerve Hypoplasia – 10%
Coloboma – 7%
Cataracts -6%
Albinism - 5%
Optic Atrophy -2%
Congenital CVI Diagnosis and
Evaluation
• Diagnosis of exclusion and based on history
information.
• Perinatal hypoxia/ischemia, Traumatic Brain
Injury (TBI), encephalitis and meningitis.
• About 75% have accompanying neurological
deficits in a recent study.
Common Causes
of CVI in Children
• Hypoxic Ischemic Encephalopathy (HIE) term
infant
• Periventricular Leukomalacia (PVL) pre-term
infant
• TBI– shaken baby, accidental head injuries,
meningitis, shunt failure, severe seizures,
cardiac arrest, CNS developmental delays
Demographics of
Congenital CVI
• Congenital cortical visual impairment is more
common in wealthier nations.
• Considered to constitute between 0.07% and
0.22% of the total school population in the US.
Congenital CVI
Common Signs and Symptoms
• Vision appears variable, even hour to hour
• Children with CVI may be able to use their peripheral
vision more efficiently than their central vision.
• One third are photophobic, others are light gazers.
• Color vision is generally preserved.
• The vision of children with CVI has been described as
“looking through a piece of Swiss cheese”.
• May exhibit poor depth perception, influencing their
ability to reach for a target.
• Vision may be better when either the visual target or
the child is moving.
Congenital CVI
Common Signs and Symptoms
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Blunted or avoidant social gaze
Brief fixations, intermittent following
Reduced visual acuity
Visual field loss - generalized constriction,
inferior altitudinal, hemianopic defect
• Reduced responses to visual stimuli when
music, voices, and other sounds are present,
and often, when the child is touched
Dorsal Visual Systems
disrupted with CVI
Dorsal “where is it pathway” associated with posterior
parietal (occipital) lobe lesions cause
• Visual motor disturbances
– deficits in fixing direct visual attention to an object
– shifting fixation and gaze to new stimulus
– fine motor tasks such as copying and drawing
• Visual Spatial disturbances
– localization of objects
– judgment of direction and distance objects
– orienting the body to the physical world
Ventral Visual Systems
disrupted with CVI
• Ventral “what is it” aspect of vision – inferior
temporal lobe lesions
– Discrimination
– Recognition
– Integration of visual images and objects
Team Players for Rehabilitation
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Physical Medicine Rehabilitation Physician
Pediatrician
Neurologist
Physical therapist
Occupational therapist
Speech therapist
Occupational Therapist
Teacher of the Visually Impaired
Optometrist
Orientation and Mobility Specialist
Congenital CVI Management and
Intervention
• Case Example
– CS 12 year old Caucasian male
• 28 week premature, birth weight 1 lb, 15 oz.
• Central apnea, ototoxicity (Gentamicin) with hearing
loss
• Cochlear implants at age 3
• Currently in good health, wheelchair bound with head
rest (cannot sustain erect head posture)
• Inclusion sixth grade, resource and lifeskills, OT, PT and
ST at school. TVI and O and M
• Uses a Dynavox for communication, Smart board
Assessment
• Cardiff Cards (preferential viewing) were utilized for
visual acuity with contact lens correction:
OD, OS 20/40
(Previous exams spanning 7 years started with VA of OD
20/130, OS 20/130 with gradual improvement)
• 30^ Alternating Exotropia
• Vertical gaze palsy with more restriction in downgaze
than upgaze, horizontal eye movements are intact
• Full visual fields in each eye
Assessment
• Normal color vision with Pease Allen preferential
viewing plates
• Intact contrast with Hiding Heidi cards 1.25%
• Normal accommodative response (MEM
retinoscopy)
• Refractive error :
Right eye: +1.75 – 1.25 x 170
Left eye: +0.75 -0.50 x 170
• Ocular health evaluation demonstrated intact
structures internal and external
Plan
• CS Qualifies for vision services
• Position objects at midline horizontally due to the vertical
gaze palsy.
• Color coding may be used for education.
• Not necessary to use high contrast materials for education.
• Continuation of contact lenses is recommended. Lenses
ordered after Medicaid approval will be as follows:
Acuvue Oasys Right eye: +1.75 -1.25 x 170, 8.6, 14.4,
Left eye: +0.50 -0.75 x 170, 8.6, 14.4.
• Materials for near should be at least ¼ inch at 16 inch working
distance.
• Return in one year for annual evaluation.
Causes of Adult Cortical Visual
Impairment
• Cerebrovascular Accidents (CVA)– 700,000 per
year in the US
– The largest group of visual disorders after acquired
brain injury are homonymous hemianopsia (HVFD).
Approximately 20-30% of all patients with CVA
requiring treatment in a rehabilitation center have
HVFD.
– It should be noted that 40% of HVFD recover after stroke,
especially within 2 months of the stroke
• Traumatic Brain Injury - 85,000 people suffer long term
disabilities
– In the U.S., more than 5.3 million people live with
disabilities caused by TBI
Acquired CVI
Diagnosis and Evaluation
• MRI/CAT scan would indicate location of
damage which would lead to diagnosis of CVI
• Varied levels of improvement of visual field
and visual acuity after sometimes total loss of
vision with CVA or TBI
Team Players for
Adult Rehabilitation
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Physical Medicine Rehabilitation Physician
Neurologist
Internal medicine physician
Physical therapist
Occupational therapist
Speech therapist
OT/CLVT
Optometrist
Orientation and Mobility Specialist
Acquired CVI
Common Symptoms
• Most common vision loss is hemianopsia
• Less common is bilateral occipital loss with
near or total blindness
• Usually no strabismus or other ocular disorder
• Anton Syndrome – the patient may deny the
vision loss entirely, may be aware of color
• Patients may be able to navigate the
environment despite serious vision loss
“Blindsight”
Blindsight
• Existence of 2 extrastriate pathways for objects and spatial
vision
– Ventral stream projecting to the inferior temporal lobe – the
“what” pathway
– Dorsal stream projecting to the parietal lobe – the “where”
pathway
• Recent studies of patients with lesions in V1 provide some
evidence for existence of connections (remaining
perception of motion) or the Riddoch phenomenon
• Cat study demonstrated transient deficit with recovery in a
matter of days, probable relocation to similar structures.
Rushmore RJ, Bertram P, Valero-Cabre A Recovery of function following
unilateral damage to visuospatial cortex Exp Brain Res (2010) 203: 693-700
Rehabilitation of “Blind” Areas
• Jobke S, Kasten E, Sabel B Vision Restoration Through
Extrastriate Stimulation in Patients with Visual Field
Defects: A Double-Blind and Randomized Experimental
Study Neurorehabilitation and Neural Repair 2009;23:246255
• Study with 21 subjects with lesions older than 1 year in trial
• Crossover study design
• Standard Vision Restoration Therapy (VRT) (using single
point visual stimulation in areas of residual vision) and
Extrastriate VRT (visual stimulus activating extrastriate
pathways) were utilized
• Extrastiate VRT utilized a massive moving spiral to address
motion perception throughout the entire defective visual
field (absolute blind region only)
Rehabilitation of “Blind” Areas
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Evaluation tools High Resolution Perimetry
Conventional Perimetry
NEI VFQ
Trained ½ hour daily with large spiral stimulus for 90 days
Control group trained with standard VRT for the same time
Improvement in detection performance of 4.2% compared to
standard VRT, improvement also found deep in the blind area
• Reasons? Magnocellular pathway – direct connection from
lateral geniculate nucleus to V5 in humans is under
investigation
• Possible evidence for direct thalamic functional pathway to
extrastiate visual cortical motion in humans which bypasses
primary visual cortex (Schoenfeld et al 2002)
Acquired CVI Case 1
• LJ 61 year old AAM
• +HTN, +DM
• Admitted 10/8/09 for progressively worsening
HA
• Ischemic stroke with conversion to
hemorrhagic stroke
– Angiogram demonstrated complete occlusion of
left vertebral artery
– Bilateral hemianopsia is reported
Acquired CVI Case 1
• OT/CLVT notes 10/29/09
– Patient reports peripheral vision is “fuzzy” like an
“unfocused TV screen”.
– Denies difficulty with central vision or with
locating objects in hospital room. Could read
short paragraph without errors
– Denied difficulties with mobility or participation in
therapy due to vision
– Recommended low vision evaluation, patient was
told by physician he could not drive
Acquired CVI Case 1
• Exam with OD 01/25/10
– Reports vision has improved since the stroke. It is
still blurry. Previously couldn’t identify
information in front of him, now peripheral vision
is better as well. He does have difficulty with
steps, particularly stepping up. Glare outdoors.
– Goals: Driving, reading with less “work”
Acquired CVI Case 1
• Distance VA sc
– 20/20 each eye
• Near VA sc
– OD 20/40, OS 20/30
– Mild compound hyperopic refractive error,
presbyopia
– Eyes are aligned with cover test
– Meibomian gland disease
Acquired CVI Case 1
• Visual fields assessed with gross confrontations
and Humphrey visual fields with only the inferior
left quadrant appearing intact in each eye or
– Right homonymous hemianopsia with superior left
quadrantopsia
• Plan
– New spectacles
– Re-evaluate visual fields on follow-up, Dynavision,
Reading evaluation
– No driving at this time.
– Warm compresses, Refresh tears
Acquired CVI Case 1
• OD 3/22/10
• LJ reports vision still isn’t the same in
periphery as prior to the stroke, but it is much
better. Warm compresses and drops are
helping, glasses are working well.
• Central distance vision is stable
• Visual fields on HVF – Kinetic and Estermann
– Fairly intact far peripheral visual fields with
constriction in paracentral area in each eye
Acquired CVI Case 1
• OT/CLVT 3/22/10
• Pepper reading test
– Corrected reading rate (WPM) 52.9
– Contextual reading rate (WPM) 84.65
• Dynavision
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135 total hits, 1.77 average reaction time per hit
Upper left 1.81
Upper right 2.24
Lower left 1.50
Lower right 1.35
• Less than 175 hits, questionable safety with driving, cautioned no
driving at this time.
• Return in 3 months for reassess, hasn’t returned
Dynavision
Acquired CVI Case 2
• RA 78 year old CM
• Diagnosed with optic atrophy secondary to past
CVA, strong history of carotid disease with history
of right carotid endarterectomy, also history of
error in medication with over dose of
hypertensive medication
• O&M evaluation – Lives in a high rise, difficulty
with curbs, if he moves reports when he moves
he can make out objects in the environment, sees
colors well.
• Cane training was started at the next visit.
Acquired CVI Case 2
• Evaluated by OT/CLVT reports difficulty
writing, mobility, using microwave
• Dynavision completed with great difficulty
with most difficulty in upper left and lower
right quadrant
– Worked with OT/CLVT on caning training and
required moderate verbal cues in order to scan in
systematic fashion
– Lighting eval completed to assist with lighting in
home
Acquired CVI Case 2
• Evaluated by OD
– Reports keyhole of vision in the right eye with good vision
in that area, his vision in the left eye has improved from
nothing to light and dim objects. He can read words and
letters, but they run together. Eyes water and hurt.
– Goals – improve reading ability and find information at
longer distance.
– Distance VA OD 20/25+2, OS 3/350 (NLP 2 months prior in
eye clinic).
– Refraction compound hyperopic astigmatism
– Near vision Right eye .3/.4M
– Contrast Peli Robson 1.2
Acquired CVI Case 2
• Low Vision Devices
– Appreciated demonstration of -5.00 minifier for
near to increase visual field
– CCTV appreciated for increase reading with
reversed contrast and stage movement
– 2.8x Hand-held telescope used as reverse system
with VA 20/40
– Superficial punctate staining of cornea
Acquired CVI Case 2
• 2.8x Telescope, -5.00 Minifier, CCTV were
ordered dispensed and trained
• Next visit BITA lens was prescribed later
dispensed with success.
• Veteran met all vision rehabilitation goals.
Rare Disorders with Cortical Visual
impairment
– Balint’s syndrome – paralysis of gaze with haphazard
scanning. Damage to the posterior parietal cortex.
Damage to the posterior superior watershed areas or
parietal-occipital vascular border zone or temporaloccipital damage.
• Optic Ataxia – incoordination of hand and eye movement
• Oculomotor Apraxia -the inability to voluntarily guide eye
movements/ change to a new location of visual fixation
• Simultanagnosia - the inability to perceive more than one
object at a time, even when in the same place
Treatment includes compensatory strategies
Rare Disorders with Cortical Visual
Impairment
– Blindsight –
• Type 1 patient has no awareness of any stimuli, but can report
accurately location or movement of an object.
• Type 2 – when subjects have some awareness of movement within the blind
field, but not able to report what the object is.
– Hemispatial Neglect – also called hemineglect, spatial
neglect or neglect syndrome
• Damage to the parieto -occipital area of typically right side of brain
• Deficit in attention to and awareness of one side of space
– Alien hand syndrome – the hand has “a mind of its own”
• Caused by lesion of corpus callosum, could be secondary to
surgery for epilepsy
Tips for work with CVI
• Control visual input to avoid over stimulation
• Eliminate extraneous noise or visual distractions
from environment
• Present one item at a time
• Touch should be used to cue
• Use language to label objects and describe
objects
• Movement may assist child or adult to “find”
objects (i.e. allow them to move or rock, bring
food into mouth of child in an arc when feeding)
References
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Bouwmeester L, Heutink J, Cees,L The effect of visual training for patients with
visual field defects due to brain damage: a systematic review
Zhang X, Kedar S, Lynn MJ,Newman NJ, Biousse V Natural history of
homonymous hemianopsia Neurology 2006;66:901-905
Rushmore RJ, Payne B, Valero-Cabre A Recovery of function following
unilateral damage to visuoparietal cortex Experimental Brain Research (2010)
203:693-700
www.Current Perspectives by Luisa Mayer, PhD
Boyle N, Jone DH, Hamilton R, Spowart K, Dutton GN Blindsight in Children
does it Exist and can it be used to help the child? Observations on a case
series Developmental Medicine and Child Neurology 2005, 47:699-702
Jobke S, Kasten E, Sabel B Vision Restoration Through Extrastriate Stimulation
in Patients with Visual Field Defects: A Double-Blind and Randomized
Experimental Study Neurorehabilitation and Neural Repair 2009;23:246- 255
Schoenfeld MA, Heinze HJ, Wodorff MG. Unmasking motion-processing
activity in human brain area V5/MT + mediated by pathways that bypass
primary visual cortex. Neuroimage.2002;17:769-779
Schoenfeld MA, Noesselt T, Poggel D, et al. Analysis of pathways mediating
preserved vision after striate cortex lesions. Ann Neurol. 2002;52:814-824.
Thanks!
Kia B. Eldred, OD, FAAO
Diplomate in Low Vision
[email protected]