Carl Garbus, O.D., F.A.A.O.Neuro Vision Rehabilitation InstituteValencia, CA

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

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

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

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

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

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

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

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

Frequently bumps into objects like door-frames

Difficulty moving crowded areas Unsteady balance in walking Problems finding objects on desks

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

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

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

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

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

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

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 2.4%1.4% Demyelination

• Midget ganglion cells (P-cells)>70% cells that project to LGNOrigin of Parvocellular pathway

• Parasol ganglion cells (M-cells)10% of all cells projecting to LGNOrigin of Magnocellular pathway

• Bi-stratified ganglion cells Lateral Geniculate Nucleus

8% of all cells projecting to LGNBlue/Yellow color signals

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

CENTRAL PERIPHERAL

Predominantly fovea, cones (r/b/g)

Predominantly Parvocellular

Sustained

Focal

What?

Cognitive

Predominantly peripheral retina, rods

Only Magnocellular

Transient

Ambient

Where?

Visuomotor

CENTRAL PERIPHERAL

Conscious Pathway Retino-calcarine Pathway Predominantly ON -> LGN (4P/2M) -

> V1 (80%) -> Ventral Stream—”What”? (4P) to

IT .......or ->

Responsible for object identification Color, high spatial frequency, low

temporal frequency, high contrast

Relatively slow system

Sub-cortical Pathway Tectal Pathway Predominantly ON -> SC ->

parietal-occipital (20%)—only Magnocellular

Dorsal Stream—”Where?” (2M) to PIP

Responsible for object localization Low spatial frequency, high

temporal frequency, low contrast, motion

Much faster / “reflexive” system

• 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)

• Parvocellular (P) pathway (what?)– Visual acuity– Color discrimination (sensitive to red-

green)– Contrast sensitivity (high spatial

frequency)– Visual Evoked Potential

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

A deficit in attention to and awareness of one side of space

The patient’s eyesight is fine, but half his visual world no longer seems to matter

Most common is left sided neglect Patient’s more prone to bumping

into things on one side and won’t attend to things on one side

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

• 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

• 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

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)

• 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

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

Peli Prisms Primarily to locate objects outside the

patient’s 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

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

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

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

Bilateral Movements in Space Motor Equivalents Interactive Metronome

Extension and Rotation Movement into the area of field loss Weight shifting (seated, standing) Balance

Obstacle Course

Scanning Turning Fixations Eye Movements Full Length Mirrors

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

24th Annual Multi-disciplinary Conference

Renaissance Denver May 14-17, 2015 Denver, CO Website www.nora.cc

Email: noraoptometric@yahoo.com

Carl Garbus, O.D. NORA Immediate Past President 28089 Smyth Drive Valencia, CA 91355 Office: 661-775-1860 Email: cgarbusod@gmail.com