Cortical Visual Impairment and Blindness

Functional Implications and Rehabilitation

Kia B. Eldred, OD, FAAODiplomate in Low Vision

Michael E. DeBakey VAMCand 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 Childrenin the U.S.

• 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 CVICommon 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 CVICommon Signs and Symptoms

• 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

• 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 170Left 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 CVIDiagnosis 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

• Physical Medicine Rehabilitation Physician• Neurologist• Internal medicine physician• Physical therapist• Occupational therapist• Speech therapist• OT/CLVT• Optometrist• Orientation and Mobility Specialist

Acquired CVICommon 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;23:246- 255

• 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• 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– 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 temporal-occipital 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

• 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, FAAODiplomate in Low Vision

kia.eldred@va.gov