1. MOTOR EVALUATION
OF STRABISMUS
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Gauri Shankar shrestha, M.Optom, FIACLE
Lecturer
Sameer Bhaila, B.optom II year

2. Contents
 Introduction
 Detection of phoria and tropia
Position of the globes
Observation of head position
 Determination of presence of deviation
 Measurement of deviation
Objective methods
Subjective methods
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3. BINOCULAR VISION
 Vision achieved by co-ordinated use of both
eyes.
 The image which arise in each eye separately
are appreciated as a single mental impression
 Mainly three mechanisms
a) Sensory
b) Motor
c) Central
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4. Motor Mechanism
 Concerned with maintenance of two eyes in
correct positional relationship at rest and during
movement.
 Motor mechanism includes following factors
Anatomical or static factor
 Structure of orbits and their contents
Physiological or dynamic factors
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5. Physiological factor
a) Postural reflex
 Movement of eyes co-ordinate during the
movement of head relative to body or body
relative to space.
Independent of visual stimuli.
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6. b) Psycho-optical reflex
Dependent on visual stimuli.
Fixation reflex
Re-fixation reflex
Conjugate reflex
Disjunctive or vergence fixation reflex
Corrective fusional reflex
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7. c) Kinetic reflex
Maintenance of two eyes in their correct
relative positions within orbits as a result of a
controlled accommodation convergence
relationship.
Accommodative convergence
Convergence induced accommodation
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8. HETEROTROPIA: A manifest strabismus
HORIZONTAL- esotropia or exotropia
VERTICAL- hypertropia or hypotropia
TORSIONAL- incyclo or excyclodeviation
Combined horizontal, vertical and/or torsional
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9. Concomitancy
 Concomitant strabismus
The deviation does not vary in size with direction
of gaze or fixating eye
 Noncomitant strabismus
The deviation varies in size with direction of gaze
or fixating eye
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10. Observation of head posture
 Patient with comitant horizontal heterotropias have
normal head position.
 Head position in nystagmus
 Possibility of head to turn into null direction
 Patient having high U/L amblyopia turn their head
away from amblyopic eye
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11.  Abnormal head positions common in connection
with incomitant and paretic deviations
 Purpose: relieve the paretic muscle sufficiently so
that binocular single vision can be obtained.”
-Bielschowsky

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Observation of head posture

12. Abnormal head position take either the form of
tipping the chin up or down, a face turn or a
head tilt to one shoulder.
 Patient with A and V pattern deviation tend to
carry head with chin depressed or elevated.
Patient with right lateral rectus paresis turn face
to right.
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13. Subjective Tests
Diplopia test
 Red Glass test
 Tangent screen
 Maddox Rod
 Maddox Wing
 Maddox double rod test
Haploscopic test
 Lancaster R-G test
Von Graefe method
Measurement of Deviation
Objective tests
Prism and cover test
Major Amblyoscope
Corneal reflection tests
 Hirschberg Method
 Krimsky’s Method
Ophthalmoscopy
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14. OBJECTIVE TESTS
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15. Determination of presence of deviation
COVER TEST
 Differentiates
 The deviation is latent or manifest
 The direction of deviation
 The fixation behavior
 Whether visual acuity is significantly decreased in one
eye
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16. Factors to be specified during a cover test
Factor specified Choices
Type of deviation Phoria or Tropia
Frequency (if strabismic) Constant or Intermittent
Laterality (if constant
strabismic)
Unilateral or Alternating
Magnitude In prism diopters
Direction Eso, Exo, Hypo, Encyclo, Excyclo
or combination
Comitancy Comitant or Incomitant
Refractive correction In Diopters
Test distance In meters
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17. PRISM and COVER TEST
 There will be no
movement of the eyes when
the selected prism causes
the image to fall on the
fovea.
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18. Inaccuracy can be caused by
1. Inaccurate fixation due to blind eye
2. Presence of eccentric fixation
3. Inappropriate positioning of prism
4. Effect of refractive correction
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19. MEASUREMENT with the MAJOR
AMBLYOSCOPE
Consists of
1. Chinrest
2. Forehead rest
3. Two tubes carrying targets seen through an
angled eye-piece one for each eye
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20. SYNAPTOPHORE
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21. Use
 Artificially performs cover tests
 Measure subjective and objective angle of deviation
 Measures horizontal, vertical, oblique deviation
 Measures fusion ranges
 Measures the grades of BSV
 Measure ARC, Suppression, stereopsis, Horror
Fusionis, measure foveal scotoma
 Useful in visual training
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22. CORNEAL REFLECTION TESTS
(Hirschberg Method)
 Estimation/ measurement of the deviation by
observing the first purkinje image
 Especially preferred when:
In young children, unable to maintain fixation for a
longer than a moment
The amount of deviation cannot be determined by
the prism and cover test or by any subjective tests.
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23. 07/24/14 23

24.  1mm of decentration of the corneal reflection
 =7° of deviation of the visual axis
Hirschberg
 1 mm displacement ~7 or 15
Brodie 1987
 1mm displacement~20-22
Hasebe at al 1998
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25. 07/24/14 25

26. Krimsky’s method
 Prism is used to change the position of the
corneal reflection in the deviating eye.
 Amount of prism needed to reposition corneal
reflection in the deviating eye to the normal
position
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27. 27

28. OPHTHALMOSCOPY
 Fovea – 0.3 dd
below a horizontal
line extending
through the
geometric center of
optic disc.
28
Excyclotortion Incyclotortion

29. SUBJECTIVE TESTS
Based on
Diploscopic principle
Haploscopic principle
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30. DIPLOSCOPIC TEST
 Determination of the subjective localization of
a single object point
imaged on the fovea of the fixating eye and
on extra-foveal retinal area in the other eye
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 Red glass test
 Tangent screen
 Maddox rod
 Maddox wing
 Double Maddox rod
 Bagolini Striated lenses

31. Red glass test
 A red glass is placed in front of one eye.
 Pt fixates a small light source and states whether the
red light is to the right or to the left and above or
below the white light.
 If the white fixation light is in the center of the
maddox cross, pt must state the numbers near which
the red light is seen.
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32. 07/24/14 32

33. Tangent screen test
 A green Maddox rod is held before the pt’s
right eye while the left eye views a scale of red
trans-illuminated number.
 The white light at the center of the scale
produces the streak, while the red numbers and
green colored rod eliminate the additional
streaks
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34. Maddox rod
 Consists of small glass rods (a
series of plano-convex
cylinders in red or white)
causes an astigmatic
elongation of the fixation light
 Produce a vertical or
horizontal streak to measure
the horizontal and vertical
deviation.
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35. 35

36. Vertical rod to measure the vertical
deviation
 Maddox rod is oriented vertically in front of one eye
and a measuring prism in other
 Starting with 8 or 10 prism base up or base down
prism the amount of prism power is gradually
reduced until pt reports the horizontal streak goes
through the spot
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37. 37

38. Horizontal rod to measure lateral phoria
 Uses horizontally oriented distance test chart having a
spot light in center and numbers or letters extending
on either side
 Horizontally oriented Maddox rod is placed in front
of one eye and the pt is asked to report the position of
the vertical streak, the number letter or through the
spot.
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H G F E D C B A 0 1 2 3 4
5 6 7 8

39.  Maddox rod on RE
If light streak pass through numbers
Uncrossed diplopia- esophoria
through letters
Crossed diplopia- exophoria
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H G F E D C B A 0 1 2 4 5
6 7 8
H G F E D C B A 0 1 2 4 5
6 7 8

40. 4007/24/14

41. Maddox wing
 For amount of heterophoria in near fixation (1/3m)
 A vertical arrow is presented to one eye and a
horizontal tangent scale to the other to give the
measurement of the horizontal phoria .
 A horizontal arrow and vertical scale are used to
measure the vertical imbalance.
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42. MADDOX WING
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43. 43
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44. Maddox double rod test
 Quantitative determination of cyclodeviation
 Red and white maddox rods are placed in the trial
frame in front of each eye.
 Direction of glass rods is aligned with the 90° mark of
trial frame

45.  A spot light is shown, for which the pt sees
horizontal streaks.
 If one line appears slanted toward the nose,
excyclotropia is present.
Maddox rod is turned until the red line is seen
parallel with the white line. E.g. toward the 100°
mark of the right trial frame, 10° right exotropia is
present
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46. 07/24/14 46

47. Bagolini striated glasses
Produce an image of a
streak of light,
perpendicular to the
axis of striations when
viewing a spot light.
Prism can be added to
shift the streaks of light
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48. HAPLOSCOPIC TESTS
 Two test objects rather than one are presented
to the patient
 Visual field of two eyes are differentiated and
dissociated by presenting
different target with major amblyoscope
Each eye with different color filter
Polaroid projection

49. Lancaster test / R-G test
 Uses a window shade type of screen (ruled into
squares of 7cm) so that at distance of 2m each square
subtends approx 2°
 Pt wears red green reversible goggles
 2 projectors are used
 Red with examiner
 Green patient
 Image formed by projector are linear and measured

50.  In NRC,
 Separation of the streaks on the screen = deviation of the
visual axes
 Titling of streak indicates presence of cyclotropia
 Tilt of the retinal image is opposite to the tilt of the
horizontal line as seen by the observer.

51. Von Graefe Method
 The method of phoria measurement in which a
dissociating prism is placed in front of one eye and a
measuring prism in front of the other eye
 The dissociating prism should be strong enough to
cause diplopia
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52.  A base down prism is placed in front of one eye
causes the image on the retina to be displaced
downward, below the macular area, so the object that
formerly was seen straight ahead is then seen as being
displaced upward
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53. Measuring lateral phoria
 Target: vertical line of 20/20 letters
 A vertical prism of 7/8 pd is placed in front of one
eye
 A base in prism as the measuring prism in other eye
 Pt is asked to report when the two columns of letters
are on the same level.
 Prism power is reduced until the patient reports
alignment.
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54. Measuring vertical phoria
 When dissociating for the vertical phoria
measurement, base in prism is used
 Eyes are able to make much larger fusional
convergence movements than fusional divergence
movements.
 15pd BI in one eye and a measuring prism BU or BD
in other eye
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55.  Target: a horizontal row of 20/20 letters on the chart
at 6m or 40cm.
 Pt is asked to report when the two rows of letters are
on the same level.
 Prism power is reduced until the patient reports
alignment.
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56. Hess Screen Test:

57. Hess chart of Left VI CN Palsy:
Contraction of left chart and expansion of right
Left chart - marked underaction of lateral rectus and mild overaction of medial rectus
Right chart - marked overaction of medial rectus

58. Diplopia Charting:

59. Diplopia Charting:…

60. References
1. Binocular vision and ocular motility- Gunrter K
Von Noorden
2. Primary care optometry- Theodore Grossvenor
3. Clinical orthoptics-Fiona J. Rowe
4. Clinical visual optics-Bennett & Rabbetts
5. Internet
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61. Thank you...