cvi- Cortical vision impairment webinar-session-1.pdf

Cortical/Cerebral Visual Impairment

Is it one or several or entities?

Can it co-exist with ocular impairments?

SESSION ONE

Barry S. Kran, OD, FAAO

Darick W. Wright, MA, COMS, CLVT

D. Luisa Mayer, PhD. MEd

Webinar Objectives

Increase understanding of the diversity of signs

and symptoms of vision impairment secondary to

pediatric brain damage/maldevelopment

Understand the difference between brain-related

or non-brain related classifications of vision loss

What is What?

“What about a premie with some ROP, but

not blinding, and maybe a little brain injury

but not a devastated brain?”

“Some TVI’s say it is really important for

them to know if a child’s poor vision is due

to the brain or the eye (retina) because

they would teach them differently”

Comment by Pediatric Ophthalmologist

From 24 wks to term, each

cortical neuron establishes

~1000 synaptic connections

– In the last trimester,

several hundred million

synapses are created

every minute!

Wyatt JS. Mechanisms of brain injury in the newborn. Eye (2007)12, 1261-63

http://library.thinkquest.org/C001501/brain/braindevelopment.htm

Accessed 07/09/2010

Brain Development

Preterm brain injury

• Focal & generalized

white matter

abnormalities (PVL) – Impaired cortical folding,

reduced grey and white

matter volumes

– Reduced growth and

development of posterior

corpus callosum and its

connections

http://neonatology.ucsf.edu/specialized-care/cerebral-palsy.aspx

Accessed 9 July 2010

Pediatric Brain Damage and

Visual Impairment

– Cerebral palsy

– Poor gross & fine motor skills

– Poor adaptive functioning

– Lower intelligence quotient

– Behavioral & emotional problems

– Asthma

– Visual pathway abnormalities

(e.g.; ROP, myopia, strabismus)

– Cortical/Cerebral VI

O’Connor AR, Wilson CM, Fielder AR. Ophthalmological Problems associated with premature birth. Eye (2007)21, 1245-60

http://www.nytimes.com/imagepages/2007/08/01/health/adam/

18117Grayandwhitematterofthebrain.html Accessed 11 July 2010

Preterm infants are at risk for:

Pediatric Brain Damage and

Visual Impairment

http://neonatology.ucsf.edu/specialized-care/cerebral-palsy.aspx

Accessed 9 July 2010

Hypoxic ischemic

encephalopathy

(HIE) – Diffuse brain damage

• cerebral cortex,

thalamus and brainstem

– Problems with motor

control, cognition,

emotions, learning

– Cortical/Cerebral VI

Brain injury at Full term is different than injury at Preterm

Pediatric Brain Damage and

Visual Impairment

Primary Visual Pathway

Ocular structures

Optic tracts to the

LGN and on to

the primary

visual cortex http://www.nature.com/nrn/journal/v6/n3/images/nrn1630-f4.jpg

Accessed 11 July 2010

Classification of Vision Loss

• Ocular

– Eye structures, to chiasm

• Ocular motor

– Brain stem, basal ganglia, thalamus,

cerebellum

• Cortical

– Primary pathway (post-chiasm to occipital)

• Cerebral

– Post-occipital, complex brain processing areas

DL Mayer

2.28.10

Ocular

Ocular media, retina,

optic nerve, to chiasm

Cerebral post-V1

(parietal, temporal lobes,

motor cortices & frontal lobes)

Cortical post-chiasm to V1

(striate or occipital)

Ocular Motor Brain stem,

cerebellum

CLASSIFICATION OF

VISUAL IMPAIRMENT

BY CAUSE

Ocular Vision Impairment

Pre-chiasmal visual pathway

Eyes, retina, optic nerves

– Significant uncorrected refractive

error

– Media opacities (ie. cataracts)

– Retinal lesions

– Retinal degeneration/dystrophy

– Optic nerve damage

Chiasm

Ocular Vision Impairment

Diagnostic examples:

– Retinopathy of prematurity* (retinal +)

– Achromatopsia (retinal)

– Leber congenital amaurosis (retinal)

– Albinism (macular hypoplasia and reduced ON fibers crossing at chiasm)

– Optic nerve hypoplasia*

*Brain related visual difficulties may co-occur

DL Mayer

2.28.10

Ocular

Ocular media, retina,

optic nerve, to chiasm

Cerebral post-V1

(parietal, temporal lobes,

motor cortices & frontal lobes)

Cortical post-chiasm to V1

(striate or occipital)

Ocular Motor Brain stem,

cerebellum

CLASSIFICATION OF

VISUAL IMPAIRMENT

BY CAUSE

Ocular Motor Vision Impairment

May need to be differentiated from visual

field loss, or CVI

Nystagmus

– “Nulling” head-eye positions

– Convergence null

Ocular Motor Apraxia (OMA)

– Lack of horizontal saccades

– Head thrusts to move eyes to target,

overshoot and correction to fixate

Cortical post-chiasm to V1

(striate or occipital)

DL Mayer

2.28.10

Cerebral post-V1

(parietal, temporal lobes,

motor cortices & frontal lobes)

Ocular

Ocular media, retina,

optic nerve, to chiasm

Ocular Motor Brain stem,

cerebellum

CLASSIFICATION OF

VISUAL IMPAIRMENT

BY CAUSE

Cerebrum

http://www.hermes-press.com/altstates.htm Accessed 07/13/2010

Cerebrum

http://www.hermes-press.com/altstates.htm Accessed 07/13/2010

Cortical Visual Impairment

Characteristics • Post chiasmal to occipital lobe damage

– Light gazing or withdrawal

– Better visual attention for: • Moving vs. static objects

• Familiar vs. novel objects

• Simple vs. complex environments

– Difficulty integrating gaze with reach

– Difficulty integrating looking with listening

– Poor social gaze

– Delayed visual (& other) responses

• Dr. Christine Roman-Lantzy

DL Mayer

2.28.10

Cerebral post-V1

(parietal, temporal lobes,

motor cortices & frontal lobes)

Cortical post-chiasm to V1

(striate or occipital)

Ocular Ocular media, retina,

optic nerve, to chiasm

Ocular Motor Brain stem,

cerebellum

CLASSIFICATION OF

VISUAL IMPAIRMENT

BY CAUSE

Cerebrum

http://www.hermes-press.com/altstates.htm Accessed 07/13/2010

Cerebral Visual Impairment

Characteristics

• Post occipital lobe brain damage

– Complex brain processing difficulties

– Dorsal/ventral stream dysfunctions

• Prof. Gordon Dutton

• Dr. August Colenbrander calls “Cognitive

dysfunction”

Dorsal & Ventral “pathways”

Ventral Stream – “What is it?”

Recognition of objects

Occipital lobes – Receive visual input (primary visual pathway)

Temporal lobes – input from occipital lobes

– Visual “library”

– Words, numbers, shapes, landmarks

– Faces

– Color

Ventral Stream

Occipital Lobe

Temporal Lobe

Apple!

????

Dorsal Stream

Occipital Lobe

Posterior Parietal

Motor Cortex

Frontal Cortex

Dorsal stream -“Where is it?”

Vision for action - visual attention,

visually guided movement

• Occipital - posterior parietal lobes – Integration of sensory input with attention and

during motor output, management of visual

complexity

• Feedback from frontal cortices – Motor planning, head/eye movement, visual

guidance of movement

I want it

Attend, Attend

Fixate with

Eyes

Reach

Apple!

I want it

It’s in front of me Reach with

right hand

?????

Too Much

Information!

!!!!!!!! Where do I

look???

How do I move?

G N Dutton 2012

Summary

• Brain damage that occurs pre-term is

different than damage that occurs with full-

term babies.

• Vision Loss can be classified based on

location within the brain and visual pathway

as: – Ocular

– Ocular Motor

– Cortical

– Cerebral

Summary

Visual Sequelae of Pediatric Brain Damage

A complex combination of abnormal visual

behaviors due to brain damage, with

probable subcategories that CAN co-exist

with ocular & ocular-motor categories.

Summary

• Historically, many have defined Cortical

Vision Impairment as being associated only

with the visual pathway and occipital lobe.

• Cerebral Vision Impairment involves other

portions of the brain that are required for

visual function. – Dr. Gordon Dutton’s - impact of damage to the Dorsal and Ventral

Streams on visual function.

Images & Resources

About Brain Injury www.waiting.com/brainanatomy.html#anchor2884157 Brain Injury Association - http://www.biasd.com/en_brain_map.html Wikipedia - http://en.wikipedia.org/wiki/Brain Dennison E, Hall Lueck A eds. Proceedings Summit on Cerebral/Cortical Visual Impairment April 30, 2005 2006 AFB Press NY, NY Dutton GN, Bax M, editors. Clinics in developmental medicine no. 186: visual impairment in children due to damage to the brain. London: Mac Keith Press; 2010 Hoyt CS. Visual function in the brain-damaged child. Eye. 2003;17:369–84. Kran BS, Mayer DL. Chapter 14 Vision impairment and brain damage in Taub, Bartuccio, Maino eds Visual diagnosis and care of the patient with special needs. Lippincott 2012 Lueck, A (2010) Cortical or Cerebral Visual Impairment in Children: A Brief Overview. JVIB, AFB press. Roman-Lantzy C. Cortical Visual Impairment: An approach to assessment and intervention 2007 AFB Press NY, NY

Cortical/Cerebral Visual Impairment

Is it one or several entities?

Can it co-exist with ocular impairments?

Barry S. Kran, OD, FAAO

Darick W. Wright, MA, COMS, CLVT

D. Luisa Mayer, PhD. MEd