Basics of BINOCULAR SINGLE VISION.ppt

Basics
BINOCULAR SINGLE VISION
BINOCULAR SINGLE VISION
Dr.V.Chandrasekar Reddy

BSV is the ability to use both functioning
eyes to create a single, common
perception

Binocular Vision
• our two eyes produce a single image in
the brain – a “Cyclopean image”
• creatures with binocular vision generally
have forward-facing eyes that move
together

WHY TWO EYES ?
WHY TWO EYES ?
 just to have a spare
wider field of vision when using two eyes
compared to one.
Compensation for blind spot
 Stereoscopic vision by blending slightly
dissimilar views of an object which is
then seen singly and with depth.

Binocular Single Vision
Binocular Single Vision
Pre requisites for BSV
 Clear visual axis
 Retino cortical elements of both eyes to
function in association with each other to
promote fusion
 Coordinated movements of both eyes to
achieve motor fusion

Binocular field of vision
Binocular field of vision
 Total binocular field is
about 170

 Exotrope large peripheral feild

6-8 weeks
:: Smooth pursuit eye movements.Visual
cortex layers mature.
4 months
 ::Visual acuity increases.
Volume of visual cortex reaches adult
levels.Highest synapse density.
4-5 months
:: Binocular interactions. Stereoacuity,
binocular summation of light reflex.

Binocular Vision
• animals that tend to get chased find it useful to
have a panoramic view of the world
– rabbits have almost 360 field of vision
• animals that do the chasing need to be able to
judge distance to their prey accurately
– predators tend to move fast, if they are inaccurate in
distance estimates they will starve or injure
themselves
• tree apes need to be able to judge the distance
to the next branch accurately

PRIMITIVE
Field monocular
Ahead, sides,behind
No blind area
Binocular
Small front& behind

FRONTAL EYES
total Field reduced
Blind area is large
Binocular large

Veith Muller Circle
Horopter
Panums area

Veith Muller Circle
• Mathematical horopter curve passing
through center of rotation of two eyes

Horopter
 Plane of all object points that are imaged
on corresponding retinal points

Panums area
 Region around the
horopter in horizontal
space in which single
vision is present
noncoresponding areas are
stimulated without diploia.
 Small in center(6-10 mts)
more in periphery(30-40
mts)
 Stereopsis present

Directional value of retina is intrensic physiological property of retina & brain.
Stimulation of retinal area results in visual sensation from a visual direction.

Basics of BINOCULAR SINGLE VISION.ppt

Retinal correspondence
NRC
 corresponding retinal points are located on
the same meridian and at the same
distance from the fovea in each eye

Retinal Correspondance
Retinal Correspondance
Corresponding retinal
elements are those
elements of two
retinas that give rise
to binocular vision

Components of BSV
Components of BSV
Simultaneous Macular Perception (SMP)
Fusion
Stereopsis

SMP
SMP
 Fusion of dissimilar
images
 Extrafoveal

Fusion
Fusion
Cortical Unification of similar images.
For fusion objects must be similar in size
&shape and in Panums area
Sensory
Motor

Fusion
Fusion
 Sensory fusion:: Based on the innate orderly
topographic relationship between the retinas &
visual cortex.
 Sensory fusion is the mechanism for stereoscopic
depth perception.
 Foveal.

Motor fusion
Motor fusion
Motor fusion is an anti diplopia
mechanism.
It is the vergence movement that causes
similar retinal images to fall and be
maintained on corresponding points.
Extrafoveal

Tests for fusion
Tests for fusion
Worth four dot test
Begolini glasses
Synaptophore

Worth four dot test
Worth four dot test

SYNAPTOPHORE SLIDES
SYNAPTOPHORE SLIDES

Stereopsis
 where fusion of the
slightly different
images from each eye
are interpreted to
allow a perception of
depth

Stereopsis
Stereopsis
 Develops by 3months
establishes by 6mths
 It is the highest form of
binocular cooperation
 Objects must be in
panums area
 Fusion of horizontally
disperate retinal images.

Stereopsis
Stereopsis
 It is not a form of simple fusion
 It occurs when retinal disparity is too big to
permit simple fusion but not big enough to
elicit diplopia.
 A bridge between fusion and diplopia
 This range is the basis for measurement of
stereopsis

Stereoscopic acuity
Stereoscopic acuity
 There is a minimal disparity beyond which no
stereoscopic effect is produced
 2-7 seconds of arc in lab
 15-30 seconds of arc in clinical tests
 Stereoacuity is not lower in amblyopia

Stereopsis
Stereopsis
The disparity in this scene is particularly easy to see in the
arrangement of the champagne glasses and pointing hand on the
right side of each scene, and in the relative positions face and the red
rose.

Stereopsis
Stereopsis
 Depth perception is monoocular also
 Monoocular clues
Motion parallax
Linear perspective
Overlay of contours
Highlights and shades
Size of known objects

Arial perspective
Arial perspective

•Texture gradients: Texture is more dense in a distant object than in an identical closer
object.

Fusion stereopsis
Fusion stereopsis
1. Fusion of mirror
images
2. Horizontal vertical
torsional
3. Motor component
4. Unlimited range .
Not related to IPD
1. Fusion of disperate
images
2. Only horizontally
disperate images
3. No motor component
4. Range is limited 6cm -
2000feet
( 7000 times the IPD)

Tests for stereopsis
Tests for stereopsis
Synaptophore
Stereograms
Titmus stereo test
Random dot stereograms
TNO test
Lang test
Two pencil test

Cross viewing stereograms
Cross viewing stereograms

Stereopsis tests
Stereopsis tests
two groups of clinical tests
contour stereotests Local stereopsis exists to
evaluate the two horizontally disparate stimuli
Eg: Titmus Fly Stereotest
the random-dot stereotest global stereopsis
Eg:Frisby Stereotest, the Randot Stereotest, the
Random-dot E Stereotest and the Lang
Stereotest

Titmus fly test
Titmus fly test
 Simple
 Widely used
 Not a sensitive test
 Provides mono
ocular clues

Contour stereo test
Contour stereo test
Titmus fly stereo test
 Vectograph cards
dissociate the eyes
optically
Local stereopsis
 Fly 3600 sec. of arc
 Animals 100-400
 Rings 40 - 800

Random dot stereo test
Random dot stereo test
 Julesz
 Global stetreopsis
 Butterfly test
 Fly 1200-2500

Randot
 Different geometric forms seen
 No monocular clues
 250-500 seconds of arc
 More sensitive

 Randot E test
 For young children
 500

 Randot for preschool chidren
 80-400

 Randot stereo smile test for infants 6mths

Lang test
Lang test
 No glasses required
 Stereoscopic images of a star ,car & a cat
embedded in random dots on a test card
 Separate images are provided to each eye
through cylindrical lenses imprinted on the
surface lamination of the test card
 600 –1200 sec of arc
 Suitable for uncoperative children

TNO test
TNO test
 Red green spectacles
 Provides stereopsis of
15 – 480 sec of arc
 Can be used as a
screening device

 The Two Pencil Test of Lang
3000-5000 sec of arc

Computerized testing system
Computerized testing system

Here are a few examples of occupations that depend
heavily on stereo vision:
 Baseball player
 Waitress
 Driver
 Architect
 Surgeon
 Dentist

Here are a few examples of general actions that
depend heavily on depth perception:
 Throwing, catching or hitting a ball
 Driving and parking a car
 Planning/building a three-dimensional object
 Threading a needle and sewing
 Reaching out to shake another person's hand
 Pouring into a container
 Stepping off a curb or step

Advantages of BSV
Advantages of BSV
Overemphasized
 Stereopsis
 Better perception of form color and
appreciation of dynamic relationship of body to
the environment
 Control of manipulation reaching and balance
 Larger binocular feild

Binocular single vision is one of the
hallmarks of the human race that
has bestowed on it the supremacy in
the hierarchy of the animal
kingdom
An asset with normal alignment but
becomes a liability when it is lost

THANK YOU
THANK YOU
THANK YOU
THANK YOU

ANOMALIES OF BSV
ANOMALIES OF BSV

Abnormalities of BSV
Abnormalities of BSV
 Confusion
 Diplopia
 Anomolous retinal correspondance
 Eccenteric fixation
 Suppression
 Monofixation syndrome
 Amblyopia

Confusion
Confusion
SMP
Dissmilar images project on to
corresponting points
Pheripheral

Diplopia
Diplopia
Stimulation of non corresponding retinal
points
Central & pheripheral diplopia
Small deviation---Central diplopia
More deviation---Total diplopia

Adaptations
Adaptations
Physical
1.Perceptual difference in sharpness&contour
2.Rapidly blinking nondominant eye

Cortical adaptations
Children below 10 yrs---Suppression &
ARC
Above 10 yrs---CHP

Eccenteric fixation
Eccenteric fixation
Can be present in mono & binocular
conditions
Manifests itself under monocular conditions.
Seen in non-dominant eye
Measured in monocularly
Amblyopia exists always

unsteady fixation
past pointing proportional to amount of EF
Deviation is must

Eccentricfixation
•Esotropia---nasal retina
•Exotropia---Temporal retina

Tests
Tests
 Visuoscopy
 Haidinger’s Brushes
 Foveal after image transfer
 Scanning laser ophthalmoscopy
 Maxwell's Spot

Visuoscopy
 To diagnose eccentric fixation
 The eye not being examined should be occluded.
*the direction of the fixation point relative to the
fovea
*magnitude of the deviation away from the fovea in
degrees
*whether the fixation point is steady or unsteady

Foveal off-center: The fixation point used is
1 degree or less from the fovea.
Parafoveal: The fixation point used is 1 to 3
degrees from the center of the fovea.
Paramacular: The fixation point used is 3 to
5 degrees from the center of the fovea.
Peripheral: The fixation point used is more
than 5 degrees from the center of the fovea

Distance from the optic nerve head to the
fovea is about 15 degrees
The optic nerve head diameter is about 5
degrees.

Treatment of EF
Treatment of EF
Treat as amblyopia
Stimulation by red color
Haidinger brushes
Maxwel spot
After image test
Inverse prisms

A R C
A R C
Sensory adaptation to small deviations
Binocular phenomenon
Shift in retinal correspondance
Crude binocularity in the presence of
strabismus

subjective angle
The subjective angle (S) of deviation is the
magnitude of the horizontal angle of
heterophoria or heterotropia as measured by
subjective testing methods, requiring the
patient to align the stimuli of the two eyes.

objective angle
The objective angle (H) of deviation is the
magnitude of the horizontal angle of
heterophoria or heterotropia as measured by
objective testing methods, such as cover test
or corneal reflex testing.

angle of anomaly (A)
The angle of anomaly (Angle A) is the
magnitude of the difference between the
objective and subjective angles of deviation

Harmonious anomalous correspondence
Harmonious anomalous correspondence
(HAC) occurs when the objective angle and
the angle of anomaly are equal (and, thus,
the subjective angle is zero).. It is the most
common and the most logical type of ARC.

unharmonious anomalous correspondence
Unharmonious anomalous correspondence
(UAC) occurs when the angle of anomaly is
less than the objective angle of strabismus
(i.e., A < H and H > S).

paradoxical anomalous correspondence
Paradoxical anomalous correspondence
(PAC) can be classified as either Type 1 or
Type 2. PAC is typically found in the
postoperative strabismus case

• Illustration of
paradoxical Type 1
unharmonious
anomalous
correspondence.

• paradoxical Type 2
unharmonious
anomalous
correspondence

• Bifoveal Test of Cüppers
• An angled mirror or large prism over the
dominant, nondeviating eye is used to
enable the patient to see the penlight and
maintain binocular conditions

Tests for A R C
Tests for A R C
Diplopia test
After image test
Synaptophore
Bagolini test

After image test
After image test

Color fusion testing, or luster testing, is done with red-green glasses
and an illuminated gray screen. If the patient fuses normally, the patient
sees a muddy yellow green screen. If the patient has
anomalous (retinal) correspondence (A[R]C), the screen is split

Treatment ARC
Treatment ARC
Amblyopia must be treated before treating
anomalous correspondence. The goal is
A = 0 for all testing conditions
 Prism Overcorrection
 Occlusion
 Synoptophore
 Haidinger brushes
 Free Space Fusion Training

Suppression
Suppression
adaptation to an anomaly of binocular
vision,(diplopia) like strabismus.
Suppression is a binocular phenomenon

Suppression
Suppression
Central and pheripheral
Monocular & alteranating
Facultative or obligatory

Peripheral
which means the maximum edge of the
suppression scotoma is more than five
degrees from the foveal center.
Central
which occurs within five degrees from the
center of the fovea.
The larger the deviation, the larger the
suppression scotoma.

Tests for suppression
Tests for suppression
Strabismus with NRC no diplopia and
good vision, suppression is present
Worth four dot test
Begolini lenses

Management
Management
Refractive correction
Occlusion
Alignment of visual axes
Ortoptic exercises

occupations that depend heavily on stereo
vision:
Waitress
Driver
Architect
Surgeon
Dentist

examples of general actions that
examples of general actions that
depend heavily on stereo vision:
depend heavily on stereo vision:
 Throwing, catching or hitting a ball
 Driving and parking a car
 Planning and building a three-dimensional object
 Threading a needle and sewing
 Reaching out to shake someone's hand
 Pouring into a container
 Stepping off a curb or step

Basics of BINOCULAR SINGLE VISION.ppt

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