strabismus-types

1. INVESTIGATION OF CONCOMITANCY
AND NONCONCOMITANCY
RAju kAITI
OpTOMETRIST
DhulIkhEl hOSpITAl, kAThMANDu uNIVERSITY hOSpITAl

2. DDEEFFIINNIITTIIOONN OOFF
SSTTRRAABBIISSMMUUSS
SSttrraabbiissmmuuss oorr ssqquuiinntt iiss ddeeffiinneedd aass tthhee ddeevviiaattiioonn oorr
mmiissaalliiggnnmmeenntt ooff tthhee eeyyeess..
The term strabismus is derived from a Greek word ” STRABISMOS” ,
“TO SQUINT,TO LOOK OBLIQUELY OR ASKANCE”

3. CCLLAASSSSIIFFIICCAATTIIOONN OOFF
SSTTRRAABBIISSMMUUSS
SSttrraabbiissmmuuss ccaann bbee ccllaassssiiffiieedd iinn tteerrmmss ooff::
1.DIRECTION OF DEVIATION
- Hyper deviation
- Hypo deviation
- Divergent
- Convergent

4. CCLLAASSSSIIFFIICCAATTIIOONN OOFF
SSTTRRAABBIISSMMUUSS
22.. CCOONNSSTTAANNCCYY
-- ccoonnssttaanntt
-- iinntteerrmmiitttteenntt

5. CCLLAASSSSIIFFIICCAATTIIOONN OOFF
SSTTRRAABBIISSMMUUSS
33.. CCOOMMIITTAANNCCYY
-- ccoommiittaanntt // nnoonn--ppaarraallyyttiicc::
Same amplitude of deviation in all gazes
Present in case of squint due to oculomotor imbalance
-- iinnccoommiittaanntt // ppaarraallyyttiicc::
Amplitude of deviation changes with gaze
found in paretic and restricted muscles
Concomitant – Latin Word
Concomitor: I Accompany (I Attend) : Duane

6. • Types
1. Non-concomitant (deviation differ by 10 Pd)
1. Non-paralytic (Special types of Strabismus
2. Paralytic (Paralysis of Cranial Nerve/s)

7. Differences:
Paralytic
(Incomitant)
Non-paralytic
(Comitant)
1 occurrence less common (15%) more common (85%)
2 onset usually acquired &
sudden; usually a
sign of neurological
or orbital disease;
any age
usually congenital
3 deviation secondary deviation
> primary deviation
primary deviation =
secondary deviation
4 limitation of
movement
+ -

8. Differences:…
5 comitance Only in late stages common
6 diplopia present- homonymous or
uncrossed in Esotropia;
heteronymous or crossed
in Exotropia
no diplopia
7 vertigo (nausea
or vomiting)
present - due to diplopia
& false projection
absent
8 head posture Commonly abnormal Rarely abnormal
9 false orientation
(past-pointing)
Common with recent
paralysis
rare
10 H/O Head Trauma Common Uncommon

9. Incomitant deviation
• Known as nonconcomitant/non comitant
• Strabismic deviation that changes by more than 10pd
for a given fixation distance in different directions of
gaze
• Misalignment of visual axis, marked by asymmetry
between one position of gaze and another

10. Incomitant deviation ctd..
• May be congenital or acquired
• Congenital –hydrocephalus,cerebral palsy,
antenatal infections, birth trauma etc
• Acquired-after 6 months of age, by
trauma,tumour,vascular etiologies

11. Clinical Evaluation of Paralytic Strabismus
1. Observation
2. EOM Evaluation
3. Cover Test
4. Measurement of deviation
5. Past Pointing
6. Head tilt Test
7. Diplopia/ Hess Charting
8. Force duction/ Force Generation test
9. Imaging Test (CT/ MRI)

12. Examination and Diagnosis
1.Abnormal head posture
• To compensate for deviation and to permit
BSV
• To eliminate diplopia and place eyes in most
comfortable position
• Three components-face turn/head tilt/chin up
and down

13. • Patient position the head to reduce the need
for affected muscle to contract
• Head is placed in the field of action of involved
muscle and eye moves out of field of action
• Chin elevation for weakness of vertically acting
muscles and in A/V pattern

14. Head posture:
• Face turn -horizontal
deviation
• Chin elevation or
depression –vertical
deviation
• Head tilt to one or the
shoulder –torsional
deviation

15. • In A/V pattern, to change the size of horizontal
deviation in up/down gaze to get fusion and
reduce deviation
• Head tilt to counteract torsional and vertical
diplopia
• Not present in amblyopia/suppression
• Some patients place head in opposite field to
increase the separation between diplopic images

16. B.Cover Test
• Measure primary and secondary deviation
• Head tilt measurement with loose hand held
prisms
• In recently acquired paretic deviation,
secondary angle exceeds the primary angle
• In congenital and chronic paretic deviation-similar
amount of deviation

17. B)cover test:
1. Cover-uncover test:
*cover test detects tropia
*uncover test detects phoria.

19. 2.Alternate cover test
measures total deviation(phoria& tropia)
3.prismcover test:
measures the
actual heterotropia

20. Cover Test:

21. Cover Test:…

22. Cover-Uncover Test:

23. The Alternate Cover
(Cross-Cover) Test:

24. C.Tests for Ocular Motility
• To detect underactions and overactions
• To differentiate paretic from mechanically
restricted deviations
• Check the ductions and version movements
• Head erect with penlight as fixation target
• Toy for children

25. • See limitation in eye movement that persist
despite vigorous encouragement
• Abduction/adduction/infraduction should
have at least 10 mm of rotation,supraduction
of 5-7 mm
• Over action and underactions graded from 1
to 4 depending on severity

26. Underactions denoted by – sign
,overactions by + sign
Each number represents a difference
of 25% compared with normal
movement
- 1=slight(25%)underaction,-4=eye
don’t extend beyond midline,
+4=good portion of cornea
disappears during adduction

27. • Ductions testing may not be as effective as
version testing, it rules out mechanical
restriction but don’t exclude possibility of
paresis of EOMs
• During ductions with paretic muscle, excessive
innervations will flow to that eye, so needed
movement actually be made.

28. Examination of ocular motility:
1.versions:
binocular simultaneous conjugate movement.

30. Examination of squint ctd…
1)test for ocular alignment & measurement of
deviation.
D)corneal light reflex test
i)Hirschberg test

31. ii)krimsky test:
measures
the
manifest
deviation
iii)Major amblyoscope:
separate target illumination is used which can be
moved to centre corneal light reflex.

32. E)dissimilar image test :
1. Maddox rod test
measures horizontal & vertical deviation.

33. 2. Double Maddox rod test:
measures the
cyclodeviation.
3.maddox wing test:
measures the
heterophoria.

35. Synoptophore test :
For assessing
deviation
& quantifying
binocular vision.
Can also detect
suppression &
ARC.

36. •Bielschowsky
Diplopia chart
Field of BSV
Hess chart

37. Instrumentation
• Originally to perform this test ,a black cloth 3 feet
wide by 3 and half feet long ,marked out by a series of
red lines subtending between them an angle of 5
degrees used.
• At the zero point of this coordinate system and at each
points of interaction of the 15 and 30 degree lines with
one another and with corresponding vertical and
horizontal lines ,there is red dot .
• These dots form an inner square of 8 dots and an
outer square of 16 dots

38. • The patient wears red –green goggles from which his fusion
is dissociated and holds the green flashlight
• Fixating eyes sees from red and non-fixating sees from
green .
• The patient is instructed to place the green light over red
light as much as possible.
• The examiners marks the position indicated by the patient
on the small card with a reduced copy of the screen .
• The point found by the patient are connected by straight
lines and permit the examiner to determine which ,if any
,muscles react abnormally.

39. Performing Hess Screen test

40. Hess Screen Chart
Additional information:
1. Contraction of ipsilateral antagonist
2. Overaction of contralateral synergist
3. Inhibtion palsy of contralateral antagonist.
Diagnosis
- Smallest field – Affected eye
- Field deviated maximum
towards the centre
- affected muscle
Charts with sloping fields indicate
the presence of A and v patterns

41. Consequences of EOM Paralysis
Ex: LLR Palsy
1. LMR Contract
2. RMR Overaction
3. RLR Under action

42. • The right eye is abnormal eye. The limited eye movement
is shown by the smaller field .
• RLR is underacting LMR is overacting .
• Right sixth nerve palsy.

43. Diplopia charting

44. Look for
- Gaze with maximum image separation (affected
gaze)
- Remote image belongs to affected eye
- Image crossed / uncrossed

45. Forced duction test
Force generation test
Palsy Vs Paresis
Paralytic Vs Restrictive Pathology
Positive in restrictive pathology,
negative
in paralytic.
Tug is appreciated in
Restrictive pathology.

46. Force duction test
• Also known as traction test
• Described by wolf ,Gifford and jaensch (1900-
1929).
• It is performed to differentiate between the
incomitant squint due to paralysis of EOM and
that due to mechanical restriction of the
ocular movement.

47. Force duction test
A. No restriction is encountered when rotating
the adducted eye into abduction .
B. Contracture of MR muscle prevents examiner
from the abducting the eye .

48. Procedures
• Apply several drops of local anesthesia to limbal area of
near the insertion of possibly mechanically restricted
muscle ,which will be on the opposite side of the
possibly paretic muscle. If the lateral rectus muscle ,the
anesthesia would be applied near the insertion of medial
rectus.

49. • The patient is then directed to look at a target
that is held in the direction of action of the
possible paretic muscle ,which is in the
opposite direction of action of the possible
mechanically restricted muscle .
• If a RLR was the possible paretic muscle ,the
patient would be directed to look at a target
to the right .

50. • The eye is then grasped with toothless forceps near
the limbus where the anesthesia was applied .the eye
is grasped close to the limbus to get as little
conjunctiva as possible in the forceps
• An effort is then made to rotate the eye with the
forceps in the direction of action of the possible
paretic muscle .if the lateral rectus was the possible
paretic muscle ,the eye would be grasped at the
medial limbus and the rotation attempted would be
an abduction movement .

51. • if the eye can be rotated with the forceps past
the voluntary moved limit –presence of
paretic muscle .
• FDT is positive in cases of incomitant squint
due to mechanical restriction and negative in
cases of EOM PALSY.

52. Past Pointing
• Described by Von Graefe
– Anomalies of egocentric localization

53. Park’s Bielschowsky Head tilt Test- Park’s
Procedure
Useful for only Isolated Nerve Palsy
Park’s Diagnostic Scheme
1. Which is the hyper eye in primary gaze?
– RE/LE
2. Which horizontal field of gaze (right or left) does
the hyperdeviation increase?
3. Bielchowsky Head-Tilt Test: Toward which
shoulder does the hyperdeviation increase?

54. Park’s Procedure

55. The 3 step Test Circling Method

56. Features of congenital incomitant deviation
• Infrequent diplopia
• Patients not aware of head posture
• Nearly equal primary and secondary angle of
deviation
• Amblyopia and suppression may be present
• Mild limitation of ocular movement

57. Recently acquired incomitant deviation.
• Frequent diplopia
• Patients aware of head posture
• Significant difference in primary and secondary angle
of deviation
• Absence of Amblyopia and suppression
• Severe limitation of ocular movement

58. Investigations:
Diagnosis of strabismus is mainly clinical, if any
neurological abnormality is suspected than we go for CT
Scan,MRI and neurosurgical consultation..
Conclusion:
Early diagnosis and management is essential for
eliminating the effect of most difficult conditions
-amblyopia or constant strabismus.
Treatment under 6 years of age is ideal and
allows better result.

59. References
• Practical orthoptics (5th edition)
– T. keith Lyle
• Binocular vision and ocular motility
– Gunter K. Von Noorden
• Clinical Management of Strasbismus
– Elizabeth E. Caloroso
• Pediatric ophthalmology and strabismus-
AAO section 6
• Internet

60. …..THANK YOU