Tests of binocularity

D R A N U R A D H A C H A N D R A
Tests of binocularity

Binocular vision
 A large part of our brain is devoted
to understanding visual cues
 Depth information can help us to
understand spatial relationships in
complex data set

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.

Oculocentric Visual Direction
 The visual direction of an object can be represented by a
line that joins the object and the fovea called the Principal
Visual Direction or visual axis. Based on the principal
visual direction, the direction of all other objects in the
subjects visual field is determined

Egocentric Visual Direction
 Egocentric direction is
determined by retinal
position, proprioceptive
information about the eye,
head and body position and
the vestibular apparatus.
All this information allows us to determine if a change in
retinal position is due to object movement or due to eye or
head movement
Refers to the direction of an object in space relative to
one self, rather than the eyes.

Retinal correspondence
 Corresponding retinal points-
same visual direction.
 Non-corresponding points
(Disparate points) - different
visual directions.

Retinal rivalry
 When dissimilar contours are presented to
corresponding retinal areas , fusion becomes
impossible and retinal rivalry ensues and gives rise
to conflict and confusion.
 It is explained by presence of separate channels for
right and left eyes that compete for access to visual
cortex.

Theories of binocular vision
 Correspondence and disparity
When disparate retinal points are stimulated by one
object point, diplopia occurs.
However if horizontal disparity remains within limit of
pannums area , a single visual impression with
quality of stereopsis is elicited.

Theories of binocular vision
(contd.)
 Neurophysiological theory
Hubel and Wiesel work gave rise to the theory in
which the neurophysiological basis of binocular
vision was discovered.
They identified cells described as being sensitive to
binocular depth in area 18 of the macaque cortex.

Physiological diplopia
 Disparate points give
rise to physiological
diplopia (double
vision).

For an object closer than the
fixation point crossed
diplopia occurs as the point
is imaged on the temporal
retina of both eyes.
 The image in the left eye is
seen on the right side.
Using the cyclopean eye, crossed and uncrossed
diplopia can be explored

For an object located
further than the fixation
point, the image of the
object falls on the nasal
retina of both eyes
producing uncrossed
diplopia.
This is termed uncrossed
diplopia because the image
in the left eye is seen on the
left side
BR
AL
BR
AL

Pannums area
 Within a small distance, either side of the horopter,
objects can still be fused and seen as single.
 Strictly speaking, they fall on non-corresponding
retinal points and there will be a small disparity.
The zone on either side of them horopter within
which it is still possible to see objects singly is
known as Panum’s area.
 Panum’s area does not have a fixed size but varies
depending on stimulus conditions, being larger for
big, moving objects, but is narrower for detailed
and stationary objects.

Binocular Vision
 Our eyes are separated by about
6.5 cm so our retinas each get a
slightly different view of the
world
 The right actually sees more
distance between the objects (as
well as slightly different parts of
the surfaces)

INVESTIGATIONS FOR BINOCULAR VISION
All the tests are aimed at assessing the presence or
absence of:
• Simultaneous perception
• Fusion with some amplitude
• Stereopsis
• Normal or abnormal retinal correspondence
• Suppression

 Tests for detection:-
1. Worth 4 dot test
2. 4D base out prism test
3. Red glass test
4. Bagolini striated lens test
5. Vectographic test
6. Synoptophore test

Sensory tests
 Diplopia tests
 Most dissociating
1. Maddox rod
2. Dark red filter
3. Worth 4 dot with room lights out
 Least dissociating
1. Bagolini striated lenses

 Red filter test :-
Place red glass over one eye and fixate on a single
light source
Patients with orthotropia and NRC will see one
pinkish red light
Esotropia with NRC causes uncrossed diplopia and
EXT causes crossed diplopia, neutralization of
deviation causes disappearance of diplopia

Patient with ARC will also see one light even in
presence of squint, neutralization of deviation
causes diplopia
Patient with suppression will see only one light,
white or red
Patient with alternate fixation will see
alternately red and white light
Test can be made more dissociating by using
denser red color or turning down the lights

Red filter test in NRC
and ARC

Red filter test in patient with RE
suppression

Worth Four Dot Test
 Utilizes red-green color
dissociation.
 box containing four panes of
glass, arranged in diamond
formation, which are illuminated
internally-
 2 green, 1 red and 1 white.
 red and green goggles
 distance (6m)and near
vision(33cm)

 The patient sees all the four dots.
 normal binocular response with no manifest deviation - NRC with
no heterotropia)
 with manifest squint - Harmonious ARC
 The patient sees five dots.
 red dots appear to the right - uncrossed diplopia with esotropia
 red dots appear to the left of the green dots - crossed diplopia with
exotropia
 The patient sees three green dots - suppression of right
eye.
 The patient sees two red dots - suppression of left eye.

Bagolini's Striated Glasses Test
 Micro Maddox
cylinders
 45 degree OS
 135 degree OD
 Non - refractive

Interpretation
 Crossing of the lines at right angles to each other
 If cover test reveals no shift and fixation is central, the patient has
NRC
 If cover test reveals a shift, harmonious ARC is present
 Foveal suppression scotoma (fixation point scotoma) with
peripheral fusion
 if no shift occurs with cover test, NRC exists,
 if shift occurs, ARC exists
 Single line represents suppression

Before any test is undertaken it is essential to assess
the:
• visual acuity
• fixation in the squinting eye
• direction and size of deviation

SIMULTANEOUS MACULAR PERCEPTION
This is the most elementary type of binocularity
and is tested with the help of SMP slides on the
synaptophore, which depicts objects which are
dissimilar, but mutually agnostic (e.g. presenting a
picture of a square to one eye and a circle to other).
The commonly used slides are bird and cage, lion
and cage, butterfly and net.

The term simultaneous perception does not
necessarily mean bifoveal fixation as it can also
occur in ARC. It merely indicates the presence or
absence of suppression. This term is erroneous as
it embraces both foveal and parafoveal perception
in the same definition.

Tests for Fusion
Fusion is demonstrated by using slides in which
similar pictures with different controls are
presented to the eyes simultaneously e.g. letter L
and F fused into E, rabbit with a tail and rabbit
with flower in hand, fused into one rabbit having
tail and flower

Normal fusion amplitudes are:
A) Horizontal vergences:
Convergence→ 35 ∆ to 40 ∆
Divergence → 5 ∆ to 7 ∆
B) Vertical vergence:
Supravergence→3 ∆
Infravergence→3 ∆
C) Cyclovergence →2-3 ∆

Tests for stereoacuity
 Synatophore-with slides
 TNO TEST-using red-green glass
 Randot’s &Titmus stereotest
 Lang’s test-no glasses
 Special 3D pictures
 Stereogram
 Major amblyoscope
 Two pencill test

Randot stereo test
 Most popular test
 The peripheral dot distribution are identical
 Central dots of each slide shifted horizontally,so the
horizontal disparity cause stereopsis.
 With polaroid glass,at distance of 40cm
 It test Near binocular vision

The wirt’s circles 1-10 test the stereoacuity from
400arc sec to 20arc sec.
It misses myopes of -3D at screening
Its not a real test of biological function as more than
40% child shows less than 40 arc response

 It use Randot back ground and red-green glass to
dissociate two images
 Adv—elicit quantitative response without changing
testing distance.
 Range-15arc to 480 arc

 LANG STEREOTEST 1: A simple test is designed for
stereopsis training in children based on two
principles, random dots and cylinder gratings. In
binocular vision stereoscopic shapes are recognised.
No glasses are required meaning the patients eye
movements are easily observed. Comes in wallet (car,
cat and star shapes)

Two pencil test
 It’s a gross test
 Two rod or pencil should approach
,horizontallly
 It measures grossly near 400sec of arc
disparity

Tests of binocularity

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Tests of binocularity

Similar to Tests of binocularity (20)

Recently uploaded

Recently uploaded (20)

Tests of binocularity