3 Tests for Binocular Single Vision

What are the tests for binocular vision?
During a Binocular Vision Assessment, the eye doctor evaluates both binocular vision functioning and visual perceptual skills:
Accommodation.
Convergence.
Depth perception (3D)
Fusion.
Ocular motility.
Ocular posture.
Presence of conditions that affect binocular vision functioning.
Spatial awareness / planning.

2. STRABISMUS
Course code: OD-139
MZ
KEMU
DOVS, FAHS

3. Tests for BSV
Contents
Worth Four dot/light test
Bagolini glasses
4 Prsim diopter test
Lang two pencil test
Titmus Fly test
TNO test
After image test

4. Worth Four Lights
This is a dissociation test which can be used
with both distance & near fixation to
differentiate b/w BSV, ARC & suppression.
Results can only be interpreted if the presence
or absence of a manifest squint is known at
time of testing.

6. Worth Four Lights
Apparatus:It consist of four circular lights
two green one red and one white which are
viewed through complementary red and
green goggles.
The red light is seen through the red filter
and the green lights through the green filter,
the white light is common to both eyes.

7. Worth Four Lights
Procedure:
A patient wears a red green goggles with the
red lens in front of the right eye , which filters
out all colors except red ,and a green lens in
front of the left eye, which filter out all colors
except green .
The patient then views a box with four lights,
one red, two green and one white.

8. Worth Four Lights
Results
If BSV is present all four lights are seen
If all four lights are seen in the presence of a
manifest strabismus, ARC
If two red lights are seen , left suppression is
present
If three green lights are seen, right suppression is
present
If two red and three green lights are seen, diplopia
is present

9. Worth Four Lights
If the red and green lights are seen
alternatively, alternating suppression is
present
If the patient sees 2 or 3 lights at 6m & 4
lights at 0.33m-the diagnosis is microtropia.

10. Worth Four Lights

11. BagoliniStriated Glasses
This is the test for detecting BSV, ARC 0r
suppression.
The test can be used at 6m, 33cm or in any desired
gaze position,e.g. in up & down gaze in A-& V-
patterns.
The apparatus consists of a pair of Plano glasses,
marked with fine parallel striations at 45°on one
glass & 135°on the other. When a spot light is
viewed through the glasses each produces a line
image at 90°to the axis of the striation.

13. BagoliniStriated Glasses
Procedure:
The two lenses are placed at 45°& 135°in front
of each eye & patient fixates a small light
source
Each eye perceives an oblique line of light,
perpendicular to that perceived by the fellow
eye
Dissimilar images are thus presented to each
eye under binocular viewing conditions.

14. Bagolini Striated Glasses
Results:
If the two streaks intersects at their centers in
the form of an oblique cross the patient has
straight eyes with BSV or squint with ARC
If the lines do not cross in center ,the patient
has squint with NRC and diplopia
If only one streak is seen ,there is no
simultaneous perception and suppression is
present

15. Bagolini Striated Glasses
If a small gap is seen in one of the streaks, a
central suppression scotoma (as found in
microtropia) is present but in practice this is
often difficult to demonstrate & the patient
describes a cross. This scotoma can be
confirmed with the 4Δtest
If only one line is seen, large regional
suppression is present.

16. Bagolini Striated Glasses

17. 4Δ prism test
This test differentiates bifoveal fixation
(normal BSV) from a central suppression
scotoma
Method of use:
Place a prism base –out in front of one eye
whilst the patient fixate a near target, observe
the movements.
Now repeat the test with the base-out prism in
front of the other eye & observe the movement,
in order to confirm the findings.

19. 4Δ prism test
Results:
1. In the presence of bifoveal fixation: the eye
behind the prism make an inward movement
to regain foveal fixation
The other eye will make a conjugate outward
movement (Herings’law) resulting in
diplopia,which stimulates convergence to
regain fusion.

20. 4Δ prism test
2. In left microtropia with CSS:
The patient fixates a distance target with
eyes open and a 4Δ prism is placed base out
in front of the left eye with suspected
central suppression scotoma scotoma.
The image is moved temporally in the left
eye but falls within the CSS & no
movement of either eye observed.

21. 4Δ prism test
The prism is then moved to the right eye
which adducts to maintain fixation : the left
eye similarly moves to the left (Herring's),
but the second image falls within the CSS
and no refixation movement is seen.

22. Tests for stereopsis:

23. Tests for stereopsis
Qualitative test:
Lang two pencil test;
This is a rudimentary test for the presence of
stereopsis which compares the patient’s responses
with both eyes open & with one eye covered, both in
manifest strabismus to assess if abnormal BSV is
present & in apparently straight eyes when it can
confirm the presence of BSV.
It is a very simple test requiring only two pencils & a
cover.

25. Lang two pencil test
Method of use:
The patient is given a pencil to hold vertically & is
asked to place this on top of the examiner’s
vertically held pencil, thus using horizontal
disparity detectors to locate the correct position.
The test is then repeated with one eye occluded
(the deviating or amblyopic eye if present).

26. Lang two pencil test
The subject is not given too long to perform
the test so that he does not use any monocular
or motion clues to depth.
The test is repeated several times & the
responses compared.

27. Lang two pencil test
Results:
If accuracy in locating the examiner’s pencil is
repeatedly better with both eyes open then stereopsis
is present thus confirming normal or abnormal BSV
If the response is comparable with both eyes open &
with the squinting eye covered, the squinting eye is
suppressed & BSV is absent.

28. Lang two pencil test
A person with suppression may perform this
test in both monocular & binocular
conditions.
A person with ARC passes this test only
under binocular condition.

29. Tests for stereopsis
Quantitative tests:
TNO test:
The TNO random dot test consists of seven
plates of randomly distributed paired red &
green dots which are viewed with
complementary red & green goggles.

31. TNO test
Within each plate the dots of one color
forming the target shape are displaced
horizontally in relation to their paired dots of
other color so that they have a different retinal
disparity from those outside the target.

32. TNO test
Some control shapes are visible even without red -
green spectacles,while the test targets are only
visible to an individual with stereopsis , while
wearing red-green spectacles.
The first plate contains two butterflies,the second
plate contains four circles,& the third five different
shapes; each plate has at least one image which can
be appreciated monocularly.
There is a suppression test plate with three circles.

33. TNO test
The first three plates are used to establish the
presence of stereoscopic vision & subsequent
plates to quantify it.
Because there is no monocular clues , the
TNO test provides a true positive
measurement of stereopsis than the Titmus
test, but can give the false negative errors
when fusion is poor.

34. TNO test
The disparities measured range from 480 to
15 seconds of arc tested at 40cm.
Most children are able to do this test from the
age of about 4 years.
Method of use:
The red-green spectacles are worn & the
apparatus is held at 40cm perpendicular to the
patient.

35. TNO test
The screening plates subtending 980 seconds of arc
are shown first, & if these are successfully
completed the graded plates from 480 to 15 seconds
of arc are presented until the patient is unable to
locate the three-dimensional shape correctly.
If the screening plates are not appreciated the
response can be checked with the suppression plate,
which consists of three circles, the middle one being
common to both eyes.

36. Frisby
The Frisby stereo test consists of three
transparent plastic plates of varying thickness.
On the surface of each plate are printed four
squares of small randomly distributed shapes.
One of the squares contains a hidden circle,in
which the random shapes are printed on the
reverse of the plate.
The patient is required to identify this hidden
circle.

38. Frisby
The test does not require special spectacles because
the disparity is created by the thickness of the plate
& can be varied by increasing or decreasing the
working distance ,which needs to be accurately
measured.
The disparities measured range from 600 to 15
seconds of arc.
Is is important not to allow the subject to tilt the
plate or move their head during testing as this gives
monocular clues.

39. Lang stereo test
This test combines panography with random dots.
The targets are fine vertical section that are seen
alternatively by each eye as they are viewed through
the built in cylindrical lens elements,& does not
require special spectacles.
Displacement of the random dots creates the
disparity.

40. Lang stereo test
The test comes in two versions: Lang I,with a
disparity range of 12oo-550 seconds of arc;& Lang
II, with a disparity range of 600-200 seconds of arc.
Method of use:
The card is held at normal reading distance & the
child is asked to name or point to the pictures.on the
Lang II test a star can be seen monocularly.

42. Lang stereo test
The examiner can also observe the child’s eye
movements from picture to picture on the
card. However ,the card must be held exactly
parallel to the plane of the face for the effect
to be seen.

43. Wirt or Titmustest
Three dimensional Polaroid vectograph consisting of
two plates in the form of a booklet viewed through
Polaroid spectacles.
On the right is a large fly & on the left is a set of
circles & animals, one of which is disparate in each
set.
The image seen by one eye is polarized at 90°to that
seen by the other eye when viewed through the
polarized spectacles.

44. Wirt or Titmusfly test

45. Wirt or Titmus test
The test gives monocular clues, especially
when viewing the first three sets of circles,
when it is easy to see monocularly that one
circle is displaced & therefore different from
the others.
The test is performed at a distance of 40cm.

46. Wirt or Titmus test
If only gross stereopsis is demonstrated the
apparatus should be turned through 90°, when
there is no depth effect, or one eye occluded
& the response compared.

47. Wirt or Titmus test
1. Fly is test of gross stereopsis (3000 seconds of arc),
& is especially useful for young children.
The fly should appear to stand out from the page &
the child is encouraged to pick up the tip of one of its
wings b/w finger & thumb.
In the absence of gross stereopsis the fly will appear
as an ordinary flat photograph.

48. Wirt or Titmus test
If the book is inverted,the targets will appear
to be behind the plane of the page.
If the patient states that the fly’s wings are
still ‘popping out’,then they are not
appreciating true stereoscopic vision.

49. Wirt or Titmus test
2. Circles comprise of a graded series which
tests fine depth perception.
Each of the nine squares contains four circles.
One of the circles in each square has a degree
of disparity & will appear forward of the
plane of reference in the presence of normal
stereopsis.

50. Wirt or Titmus test
The disparity measured range from 800 to 40
seconds of arc.
If the patient perceives the circle to be shifted to the
side , then they are not appreciating stereoscopic
vision, but are using monocular clues instead.
The animals are similar to the circles test but consist
of three rows of five animals each, one of which will
appear forward of the plane of reference.
The degree of disparity ranges from 400 to 100
seconds of arc.

51. After-image test
Hand held apparatus:
The apparatus consists of a linear light with a
central black band within a circular
background mounted on a flash apparatus.
The line can be presented horizontally or
vertically.

52. After-image test
Method of use:
The patient must have steady foveal fixation.
The deviating eye is covered & the line is
presented horizontally at a distance of
approximately 50cm.
The apparatus is flashed while the patient
fixates the black band.

53. After-image test
The fixating eye is then covered & the process is
then repeated with the line presented vertically.
A vertical line is more likely to fall outside the
suppression scotoma.
The patient looks at a blank wall in normal
illumination and should see two negative linear after
images each with a central gap corresponding to the
fixation and therefore representing the visual
direction of the fovea.

54. After-image test
He is asked to draw or describe the position of
the lines.
blinking may aid appreciation of the images.
Alternatively the position of positive after-
images can be assessed in a dark room.

55. After-image test
Results
A symmetrical cross with coincident gaps indicates
normal retinal correspondence
Displacement of the lines indicates abnormal retinal
correspondence the separation between the gaps is
determined by the size of the angle of anomaly there
will be crossed projection in esotropia
If eccentric fixation is present the results will need to be
assessed accordingly a symmetrical cross would then
indicate ARC.

56. After-image test

57. References
Diagnosis & management of ocular motility
disorders
Strabismus & pediatric ophthalmology by
American academy of ophthalmology