Functional Visual Field Assessment and Management

1
Functional Visual Field Assessment and Management

• Carl Garbus, O.D., F.A.A.O.
• Neuro Vision Rehabilitation Institute
• Valencia, CA

2
Introduction

• Visual fields provide the most important
  information that we have to help us with
  functional vision (daily living skills)
• The visual system uses parallel processing to
  combine information along specialized visual
  pathways
• If working properly, the brain quickly tells us
  where an object is in space and what it is

3
Introduction

• Course Objectives
• Learn how to do a confrontation field
• Understand the importance of visual fields
• Have the awareness of different types off visual
  field tests
• Learn about the application of prisms in field
  loss

4
Definitions of Visual Field

• That portion of space in which objects are
  simultaneously visible to the steadily fixating
  eye
• Visual space that can used for activities of
  daily living
• Awareness of the spatial world around us

5
Normal Field Limits

• The normal visual field extends 40 to 60 degrees
  nasally to 65 to 100 degrees temporally
• The normal visual field extends 30 to 60 degrees
  above horizontal midline and 50 to 75 degrees
  below horizontal midline
• The actual extent of the field is related to the
  size of the test object and the testing distance

6
Measuring Visual FieldsPerimetry

• Kinetic perimetry- test target moves
• Static perimetry- test target is stationary
• Automated (computerized)
• Manual
• Test target is a point of light which could be
  white or a color

7
Field Instrumentation

• Goldmann Visual Fields
• Manual and automated
• Great for detecting defects over larger areas
• Stroke, retinal degeneration and tumors
• Humphrey Visual Fields
• Automated
• Great for glaucoma detection and follow-up
• Great for central field defects

8
Field Instrumentation

• Tangent Screen
• Manual
• Great for monitoring attention
• Campimeter
• Manual
• Used for mapping out functional fields
• Amsler Grid (hand held)
• Quick check on the macular area

9
Confrontation Fields

• Quick and easy to administer
• Can be done with a fingers or wand
• The examiner and patient sit across from each
  other eye to eye
• Goal is to find matching fields with patient and
  examiner
• Demonstration of two different confrontation
  fields

10
Common Problems With Field Loss

• Frequently bumps into objects like door-frames
• Difficulty moving crowded areas
• Unsteady balance in walking
• Problems finding objects on desks

11
Areas of Functional PerformanceMost Affected By
Visual Field Defect

• Reading omissions, line skipping, difficulty
  navigating a page
• Activities of Daily Living self care and
  mobility
• Independent Activities of Daily Living grocery
  shopping, driving
• Balance and coordination
• Judging distance and speed of objects

12
Primary Visual Pathway
13
Types of Visual Field Defects

• Altitudinal
• Relates to a lesion in the parietal or temporal
  lobe
• Bitemporal
• Relates to a lesion near or at the optic chiasm
• Homonymous
• Most common defect from stroke and encompasses
  portions of one side of the field
• Central Scotomas
• Glaucoma and other retinal diseases

14
Functional Visual Field Defects

• In the Field of Syntonics Functional Visual
  Fields are done with the campimeter
• The field is mapped with four different test
  objects, white, blue, red and green
• Each color will elicit a different size field
• Largest is the white field, then blue, red and
  white
• When colors overlap expect visual dysfunction

15
Functional Visual Field Defects

• When an individual is under stress or is fatigued
  the functional field usually constricts
• Field constriction is a common sign of traumatic
  brain injury, autism, stroke and neurological
  disease
• With proper therapeutic techniques it is possible
  to improve and open up a constricted visual field
• The therapy program may use syntonic filters, as
  neuro vision rehabilitation

16
Retina -gt Lateral Geniculate Nucleus -gt V1

• Organic Visual Acuity Loss
• Including contrast and
• color problems
• Organic Visual Field Loss

17
Homonymous Hemianopsia

• Homonymous Hemianopsia is a common visual field
  deficit present with many stroke and tumor
  patients
• It is present in 30 of stroke patients
• Hemianopsia is not black half to the vision
• Missing vision is simply gone
• Like the area behind us

18
Spontaneous Recovery

• 254 patients with homonymous hemianopsia were
  evaluated with formal visual field
• The longer period after the insult, the less
  likely the improvement will occur
• Spontaneous seen in about 50 of patients with
  the first month
• Most improvement within three months
• After six months minimal improvement

19
Homonymous HemianopsiaCauses

• Most common vascular lesions are in the posterior
  cerebral or middle cerebral arteries
• Study showed causes
• Stroke 69.5
• Trauma 13.6
• Tumor 11.3
• Brain surgery 2.41.4
• Demyelination

20
Ganglion Cells

• Midget ganglion cells (P-cells)
• gt70 cells that project to LGN
• Origin of Parvocellular pathway
• Parasol ganglion cells (M-cells)
• 10 of all cells projecting to LGN
• Origin of Magnocellular pathway
• Bi-stratified ganglion cells Lateral
  Geniculate Nucleus
• 8 of all cells projecting to LGN
• Blue/Yellow color signals

21
Where is it? What is it?

• Magnocellular pathway (aka where) Ambient System
• Transmits information about motion and spatial
  analysis, stereopsis, and low spatial frequency
  contrast sensitivity
• Spatial vision
• Parvocellular pathway (aka what) Focal System
• Relays color and fine discrimination information,
  shape perception, and high spatial frequency
  contrast sensitivity
• Object vision

22
(No Transcript)
23
Visual Processing SemanticsParallel
Processing

• CENTRAL

• PERIPHERAL

• Predominantly fovea, cones (r/b/g)
• Predominantly Parvocellular
• Sustained
• Focal
• What?
• Cognitive

• Predominantly peripheral retina, rods
• Only Magnocellular
• Transient
• Ambient
• Where?
• Visuomotor

24
Visual Processing SemanticsParallel
Processing

• PERIPHERAL

• CENTRAL

• Conscious Pathway
• Retino-calcarine Pathway
• Predominantly ON -gt LGN (4P/2M) -gt
• V1 (80) -gt
• Ventral StreamWhat? (4P) to IT
• .......or -gt
• Responsible for object identification
• Color, high spatial frequency, low temporal
• frequency, high contrast
• Relatively slow system

• Sub-cortical Pathway
• Tectal Pathway
• Predominantly ON -gt SC -gt parietal-occipital
  (20)only Magnocellular
• Dorsal StreamWhere? (2M) to PIP
• Responsible for object localization
• Low spatial frequency, high temporal frequency,
  low contrast, motion
• Much faster / reflexive system

25
How to isolate each pathway

• Magnocellular (M) pathway (where?)
• Motion discrimination
• Critical flicker fusion
• Stereopsis
• Contrast sensitivity (low contrast is sensitive
  to rapid movement and is monochromatic)
• Frequency doubling technology (FDT) or motion
  automated perimetry
• Visual evoked potential (VEP)

26
How to isolate each pathway

• Parvocellular (P) pathway (what?)
• Visual acuity
• Color discrimination (sensitive to red-green)
• Contrast sensitivity (high spatial frequency)
• Visual Evoked Potential

27
Magnocellular pathway

• Plays an important role in visual motion
  processing, controlling vergence eye movements,
  and reading
• Provides general spatial orientation
• Contributes to balance, movement, coordination
  and posture

28
Visual Spatial Inattention

• A deficit in attention to and awareness of one
  side of space
• The patients eyesight is fine, but half his
  visual world no longer seems to matter
• Most common is left sided neglect
• Patients more prone to bumping into things on
  one side and wont attend to things on one side

29
Visual Spatial Inattention

• As you can see from the drawings, mental images
  are half too, its not related to how well the
  patient sees. It is a problem with consciousness.
• The neglect results from damage to processing
  areas (on the opposite side of the brain)
• Treatment prisms with base in direction of
  neglect
• i.e.. Left spatial inattention, use base left
  yoked prisms

30
Magnocelluar Deficits

• Disorders that involve difficulty in learning to
  read
• Causes problems with reading comprehension and
  poor reading fluency
• Complaints that small letters tend to blur and
  move around when trying to read

31
Magnocelluar Deficits

• Notoriously are clumsy and uncoordinated, and
  balance is poor
• Magnocellular theory
• If patient has binocular instability and visual
  perception instability, then reading will be
  effected
• Possible trouble processing fast incoming sensory
  information
• Combination of visual, vestibular, auditory and
  motor functions

32
Treatment for Constricted Visual Fields

• Neuro Vision Rehabilitation
• Address peripheral system with lenses, prisms and
  binasals
• Lenses (plus lenses help to stabilize the
  vestibular ocular systems)
• Prisms (typically base in or yoked base down)
• Binasals (eliminates binocular confusion)

33
Lens Treatments for Constricted Fields

• Filters
• Incorporate tints to spectacle correction
• Green combined with blue helps with
  photosensitivity
• Blue reduces ocular pain with eye movements
• Yellow reduces blue light from passing through
  the lens and helps with computer and fluorescent
  lighting

34
Therapy Program Prisms

• Prisms- what can they do?
• Affect can change the spatial orientation of the
  patient
• Can expand space or constrict space
• Are used in therapy and/or a full time
  prescription in glasses
• Need to be prescribed by a doctor

35
Therapy Program Special Prisms

• Peli Prisms
• Primarily to locate objects outside the patients
  visual field
• Peli prism is placed on the lens of the temporal
  field defect
• Upper and lower are 40 or 57 diopter press-on
  prisms
• Expand upper and lower fields by about 22 degrees

36
Peli Prisms

• May fit upper first if there are adaptation
  problems
• Never look through the prism
• If object is seen peripherally on the field loss
  side, use head turn to locate object
• Scanning is still needed
• Reach and touch training
• Practice walking and use of stairs

37
Therapy Program Special Prisms

• Sector Prisms
• Prism power is in the range of 15 to 20 diopters
• Placed on the temporal aspect of the lens on the
  side of the field loss
• Increased visual field awareness by 6-19 degrees
• Success rate depends on training

38
Therapy Program Prisms

• Yoked Prisms
• Usually 3 to 8 diopters prism base to the side of
  the field loss
• Ground in Prism
• Patient can experience improvement in posture and
  gait when it is prescribed correctly
• Visual field enhancement

39
Therapy ProgramMovement Activities Field
Enhancement

• Bilateral Movements in Space
• Motor Equivalents
• Interactive Metronome
• Extension and Rotation
• Movement into the area of field loss
• Weight shifting (seated, standing)
• Balance

40
Therapy ProgramMovement Activities Field
Enhancement

• Obstacle Course
• Scanning
• Turning
• Fixations
• Eye Movements
• Full Length Mirrors

41
Therapy ProgramVisualization- Field Enhancement

• Peripheral Visualization
• Patient is to scan into the side of the field
  loss
• Ask patient to remember as many objects to the
  side as possible
• Looking straight ahead visualize those objects
• Now have the patient point to the area where the
  object were seen
• While the patient is still pointing have them
  turn their head, so they can view the missing
  field

42
Neuro Optometric Rehabilitation Conference

• 24th Annual Multi-disciplinary Conference
• Renaissance Denver
• May 14-17, 2015
• Denver, CO
• Website www.nora.cc
• Email noraoptometric_at_yahoo.com

43
Contact Information

• Carl Garbus, O.D.
• NORA Immediate Past President
• 28089 Smyth Drive
• Valencia, CA 91355
• Office 661-775-1860
• Email cgarbusod_at_gmail.com