This document discusses motor adaptation in paresis and non-paresis strabismus. It begins by defining strabismus and describing the different types. It then discusses the consequences of strabismus and the different ways motor adaptation occurs, including through changes in muscle tone, compensatory head posture, and blind spot mechanisms. It describes how motor adaptation occurs differently in incomitant versus comitant strabismus. The document goes on to discuss various cranial nerve palsies and how they result in specific eye positions and compensatory head postures. It also covers special restrictive disorders like Duane's retraction syndrome.

1. K O P I L A K A F L E
B . O P T O M E T R Y
T H I R D Y E A R
MOTOR ADAPTATION IN
PARETIC AND NONPARETIC
STRABISMUS
Moderator :
Mr. Gaurishankhar Shrestha

2. PRESENTATION LAYOUT

3. STRABISMUS
 Aka SQUINT is deviation of eye
 Misalignment of the visual axes of the two eyes

4. TYPES OF STRABISMUS
 Can be COMITANT or INCOMITANT
INCOMITANT COMITANT
Results when there is limitation of
ocular movement
Result of abnormality in
establishment of normal BSV
Can be paralytic or non paralytic Always non paralytic
limitation of ocular movement normal extraocular motility
particular abnormal head posture
develops ,I.E motor adatation occurs
no head posture ,instead sensory
adaptation occurs
Muscle sequelae present in old cases Absence of muscle sequelae

5. EXAMPLES
INCOMITANT STRABISMUS COMITANT STRABISMUS
A . NEUROGENIC A . PRIMARY STRABISMUS
due to palsy of third ,fourth and
sixth cranial nerve
B . MYOGENIC B . SECONDARY STRABISMUS
due to problem affecting muscle
itself
C . MECHANICAL C .CONSECUTIVE STRABISMUS
due to interference with muscle
contraction and relaxation

6. CONSEQUENCE OF STRABISMUS

7. WHAT TO DO NOW?
I THINK I NEED TO ADAPT
SENSORY
ADAPTATION
MOTOR
ADAPTATION
Neither I want to see double
Nor I want to be confused

8. IN COMITANT STRABISMUS
Sensory adaptation occurs
Abnormal retinal
correspondence
suppression
amblyopia

9. IN INCOMITANT STRABISMUS
 Motor adaptation occurs

10. WAYS OF MOTOR ADAPTATION
 Control of ocular deviation by an alteration of tone of
extraocular muscles
 Compensatory head posture
 Blind spot syndrome
 Blind spot mechanism

11. Control of ocular deviation by an alteration of
tone of EOM
 Can control only small degree of ocular deviation
 active contraction or an active relaxation
compelling fusion reflexes
disappearance of squint(manifest
deviation converted to latent one)

12. BLIND SPOT SYNDROME
 In esotropia of 12 – 18 ˚ with good visual acuity in
both eye
 Normal retinal correspondence and normal fusional
vergence present
 Eye further moved to esotropic side projecting
image seen by deviating eye onto blind spot

14. BLIND SPOT MECHANISM
 Coincidental type of esotropia
 Image of fixated object falls on the blind spot

15. BLIND SPOT SYNDROME BLIND SPOT MECHANISM
Good visual acuity in both eyes Amblyopia of the non dominant eye
Normal retinal correspondence Abnormal retinal correspondence
No suppression other than fovea of the
deviated eye
ARC and suppression may coexist

16. Compensatory head posture
 Used by visually mature patients(does not
necessarily develops in every patients)
 Occurs in paralytic strabismus and alphabet
pattern strabismus
 Has 3 components

17. HEAD
TILT
FACE
TURN
CHIN
ELEVATION
OR
DEPRESSION

18. WHAT ACTUALLY IS PARALYSIS?
 Malfunctioning or dysfunctioning of nerves
 Paralysis = no movement is possible
 Paretic = some movement is possible
 Palsy = includes both paresis and paralysis
(generally used )

19. CRANIAL NERVES SUPPLYING EOMs
 Occulomotor (3rd cranial nerve) : supplies SR,IR,IO
and MR
 Trochlear nerve (4th cranial nerve) : supplies SO
 Abducens nerve(6th cranial nerve) : supplies LR

20. TO KNOW THIS FIRST WE MUST
KNOW ACTIONS OF
EXTRAOCULAR MUSCLES
WHAT HAPPENS WHEN THESE
NERVES GET PARALYSED?

21. ACTIONS OF EOM
LATERAL RECTUS
AND MEDIAL
RECTUS HAVE
ONLY PRIMARY
ACTIONS
MEDIAL RECTUS adducts
the eye
LATERAL RECTUS abducts
the eye

22. NOTES
 Vertical rectus i.e superior and inferior rectus have
their primary function as elevator and depressor
while secondary action as intorsion and extorsion
 For oblique muscle opposite is true
 SIN : all superiors are intorters
 RAD : all vertical rectus are adducters

23. LET’S TRY THEN….
SUPERIOR RECTUS
A. ELEVATOR
B. INTORTER
C. ADDUCTOR
INFERIOR RECTUS
A. DEPRESSOR
B. EXTORTER
C. ADDUCTOR
SUPERIOR OBLIQUE
A. INTORSION
B. DEPRESSOR
C. ABDUCTION
INFERIOR OBLIQUE
A. EXTORSION
B. ELEVATOR
C. ABDUCTION

25. IN CASE OF PALSY,
 Actions of muscles interrupted
 SO, eye takes its position opposite to its action
 For example,in LR palsy,eye is in adducted position
in MR palsy,eye is in abducted position

26. QUESTIONS
WHAT IS EYE POSITION
IN SUPERIOR RECTUS
PALSY?
DEPRESSED
EXTORTED
ABDUCTED
WHAT IS EYE POSITION IN
INFERIOR OBLIQUE PALSY?
INTORTED
DEPRESSED
ADDUCTED

27. Less to be worried about…
 In case of palsy, there is usually some direction of
binocular gaze in which the visual axes are
approximately parallel in which BSV can be
obtained
COMPENSATORY HEAD POSTURE

28. Normal effect of tilting the head
LE is extorted ,so tilting
to the right overcomes
this disability,visual axes
of both eye parallel

29. In primary
position without
head posture,LE
hypotropic
In
dextroversion
,parallelism of
visual axes
Updrift of
right eye in
laevoversion
Congenital
paresis of left
superior rectus,
motor adapted
condition

30. REASONS FOR AHP
TO ACHIEVE BSV :
Head turned into the field of action
of paralysed muscle
Eyes directed by DOLL’S HEAD
PHENOMENON
Patient’s limited field of single
vision coincides with his egocentric
position
Occurs when patient fixates with
normal eye
TO ACHIEVE WIDE
SEPARATION OF DIPLOPIC
IMAGES
In patients with no useful field of
vision
Turn the head opposite to the
field of paretic muscle
Deviation of the eye maximum
Occurs when patient fixates with
affected eye

31. DOLL’S HEAD PHENOMENON
 Aka tonic movements
 Influenced by labyrinthine reflex from otoliths
 When head is rotated to the right,the eye will rotate
to the left and vice-versa
 If the head is tipped backward, the eyes will rotate
downward and vice-versa

33. ALSO KEEP IN MIND
When head is
tilted to the
right shoulder,
right eye intorts
while left eye
extorts…..and
vice - versa

35. IN HORIZONTAL RECTUS PALSY
 Only one component of abnormal head posture
i.e face/head turn
 Face turn towards the action of paretic muscle
 Head turn to right :
- to maintain an ocular posture
of laevoversion
-compensate for defective
abduction of RE or defective
adduction of LE

36. To conclude,
 Esotropic eye is made more esotropic
 Exotropic eye is made more exotropic,
BUT,
BE CAREFUL
It’s not true in case of cyclovertical muscle

37. Head turn in case of cyclovertical muscle
Head is turned such that
eyes are brought away
from field in which
muscle has its greatest
vertical effect.
Right superior rectus palsy

38. e.g. for vertical rectus , having maximum effect on
abduction,face is turned so that involved eye is
adducted
i.e face is turned towards the affected eye
WHILE , for oblique muscles, having maximum effect
on adduction , face is turned such that the involved
eye is abducted
i.e face is turned away from affected eye

39. IN PALSY OF CYCLOVERTICAL MUSCLE
 Has all 3 components of abnormal head posture i.e
chin elevation or depression , face turn and head tilt

40. CHIN ELEVATION
 As chin is elevated , eye
moves down
 Occurs to maintain eye
posture of depression to
compensate for defective
elevation of eye(s)
 To conclude , hypotropic
eye is eye is made more
hypotropic

41. CHIN DEPRESSION
 In chin depression , eye moves up
 Adopted to maintain ocular posture of elevation to
compensate for defective depression of eye(s)
 To conclude hypertropic eye is made more
hypertropic

42. HEAD TILT
 In paresis of oblique muscle,
head tilt occurs to compensate the torsion caused
by the direct antagonist of paralysed muscle
E.g.in RSO palsy,head tilt occurs to the left to
compensate for the extorsion caused by RIO muscle
To conclude, extorted eye is made more extorted and
intorted eye made more intorted BUT,its not true for
vertical rectus muscle

43.  In paresis of vertical rectus muscle ,
head tilt occurs to compensate the
torsion caused by contralateral anatagonist of the
paralysed muscle
E.g in paresis of RSR, head tilt occurs to right to
compensate for the extorsion of the left eye caused
by overacting LIO muscle
To conclude,head is tilted to the side of hypotropic eye

44. Muscle
paralysed
Chin Face turn Head tilt
RSR elevation right right
RIR depression right left
RSO depression left left
RIO elevation left right
RLR _ right _
RMR _ left _

45. Muscle
paralysed
chin Face turn Head tilt
LSR elevation left right
LIR depression left right
LSO depression right right
LIO elevation right right
LLR _ left _
LMR _ right _

46. EASY STEPS
1. Know the action of the muscle
2. Know the position of the eye
3. Know what should the head and chin do to keep
the eye in that position or to make the eye more
tropic(or other reasons discussed earlier)

47. EXAMPLES..
LEFT
LATERAL
RECTUS
PALSY
EYE POSITION
TO MAKE MORE
ESOTROPIC
HEAD TURN
TO THE
LEFT

49. LEFT
MR
PALSY
EYE POSITION
TO MAKE MORE
EXOTROPIC
HEAD TURN
TO THE
RIGHT

50. Face turn to right to compensate palsy
of left medial rectus

51. IN LSO
PALSY
ACTION OF
LSO
EYE POSITION
EXTORTED
ELEVATED
ADDUCTED
HEAD
TILT TO
THE
RIGHT
CHIN
DOWN
FACE
TURN TO
RIGHT

53. Left SO palsy,head
turn with tilt in right
side
Upshoot of LE due
to contracture of
LIO
Parallelism of
visual axes in
laevo-version

54. LIR
PALSY ACTION OF IR
MUSCLE
EYE POSITION
ELEVATED
INTORTED
ABDUCTED
CHIN
DOWN
HEAD
TILT TO
RIGHT
FACE
TURN TO
LEFT

55. Compensatory head posture
in RIR ,face turn to
right,head tilt to left and
chin depressed
Dextroversion
showing depression
of left eye
Dextrodepression,
defective
movement of RE
with overaction of
LSO

56.  RSR
PALSY
ACTION OF SR
MUSCLE
EYE POSITION
DEPRESSED
ABDUCTED
EXTORTED
FACE
TURN TO
RIGHT CHIN
UP
HEAD
TILT TO
RIGHT

57. FIXING WITH NORMAL EYE
FIXING WITH PARETIC
EYE
RSR palsy, chin elevation, head tilt to
right with face turn to right(common
occurrence)
RSR palsy, head tilt and face turn
to the left (less common
occurrence)

58. In primary
position without
head posture,LE
hypotropic
In
dextroversion
,parallelism of
visual axes
Updrift of
right eye in
laevoversion
Congenital
paresis of left
superior rectus,
motor adapted
condition

59.  LIO
PALSY ACTION OF IO
MUSCLE
EYE POSITION
INTORTED
ADDUCTED
DEPRESSED
FACE
TURN TO
RIGHT
HEAD
TILT TO
LEFT
CHIN UP

60. LEFT
INFERIOR
OBLIQUE
PALSY
-HEAD TILT TO LEFT
-FACE TURN TO RIGHT
-CHIN ELEVATED

61. Mnemonics for head turn and tilt in superior
rectus and superior oblique palsy
SO U RS
SUPERIOR OBLIQUE SAME SIDE
UNAFFECTED
SIDE sUPERIOR RECTUS
THIS HEAD POSTURE IS ADAPTED TO MAINTAIN BSV
LEFT SO PALSY
LEFT SR
PALSY

62. ISOLATED VARIETIES OF OCULAR PALSY
 Most common muscles to be paralysed singly :
superior oblique and lateral rectus
WHY ? ?
BECAUSE
THEY HAVE
SEPARATE
NERVE
SUPPLY

63. In case of MR, IO, SR and IR
 Supplied by 3rd cranial nerve, less likely to occur isolated
muscle palsy…
total 3rd nerve palsy
 3rd nerve palsy
partial 3rd nerve palsy
Note: in both cases pupil may or may not be spared
in total palsy : both division involved
in partial : only one division involved
in isolated muscle palsy : only one muscle involved

64. TOTAL 3RD NERVE PALSY
 Extraocular (IR, MR, IO and SR) , LPS muscle as
well as intraocular muscle (sphincter pupillae and
ciliary muscle) affected
Dilated
pupil
Complete loss
of
accomodation
ptosis

65. MOTOR ADAPTATION IN TOTAL 3RD NERVE
PALSY
 Occcurs only if pupil is spared so that the patient
experience diplopia requires adaptation
 Eye is turned down ,out and slightly intorted
SLIGHTLY
CHIN UP FACE TURN
TOWARDS
OPPOSITE
SIDE
HEAD TILT
TO SAME
SIDE

66. PARTIAL 3RD NERVE PALSY
SUPERIOR DIVISION
PALSY :
-SR and LPS muscle
involved
-ptosis with hypotropic
eye
- Chin elevated , face turn
and head tilt to affected
side
INFERIOR DIVISION
PALSY :
-IR, IO and MR in
addition to sphincter
pupillae and ciliary
muscle involved
-exotropic,intorted and
hypertropic eye with
pupil dilatation
-unlikely to be any field of
binocular vision
-So , no need for AHP

67. Restriction of movement of LE
in all gazes except in abduction
LEFT THIRD NERVE PALSY
Head tilt and face turn to right
with chin up to avioid diplopia

68. DOUBLE ELEVATOR PALSY
 Aka monocular elevation deficiency
paralysis of both elevators of same eye
i.e superior rectus and inferior oblique
elevation deficiency in entire upgaze i.e
both upward adduction and abduction

69. Head posture
 Eyes made more hypotropic by doll’s head
phenomenon i.e chin is elevated

70. DOUBLE DEPRESSOR PALSY
 Aka monocular depression deficiency
both depressors of same eye i.e inferior rectus and
superior oblique are paralysed
depression deficiency in entire downgaze both in
adduction and abduction

72. Head posture
 Eyes made more hypertropic by doll’s head
phenomenon i.e chin is depressed

73. SPECIAL RESTRICTIVE DISORDERS
 Disorders that are non –paralytic but restricts the
ocular movement
 Caused by elements within orbit that either interfere
with muscle contraction or relaxation or otherwise
prevent free movement of globe

74. Examples ..
 Duane’s retraction syndrome
 Brown’s syndrome
 Grave’s ophthalmopathy
 Fibrosis of EOM

75. DUANE’S RETRACTION SYNDROME
 there is fibrosis or inelasticity of the lateral rectus
muscles and that the medial rectus muscle inserts
abnormally far posteriorly myogenic cause
 absent abducens nerve with anomalous innervations
of the lateral rectus muscle by a branch of the
oculomotor nerve,
Simultaneous activation of the medial and
lateral rectus muscles the cause of globe
(neurogenic ) retraction
 there is fibrosis or inelasticity of the lateral rectus
muscles and that the medial rectus muscle inserts
abnormally far posteriorly myogenic cause
 absent abducens nerve with anomalous innervations
of the lateral rectus muscle by a branch of the
oculomotor nerve,
Simultaneous activation of the medial and
lateral rectus muscles the cause of globe
(neurogenic ) retraction

76. AHP in DRS
 Adopted to centralize BSV
 Determined by deviation in primary posistion
ESOTROPIC : face turn to affected side
EXOTROPIC : face turn to unaffected side

77. TYPE I DRS
Marked limitation of
abduction
Normal or slightly
defective adduction
Narrowing of PFH on
adduction
Widening of PFH on
abduction

78. TYPE II DRS
 Marked limitation
of adduction
 Normal or slightly
defective abduction
 Narrowing of PFH
on adduction


79. DUANE’S RETRACTION SYNDROME,TYPE II
Head posture to
compensate for left
medial rectus paresis
Dextroversion ,
defective adduction of
LE and narrowing of
PFH of LE
Laevo version,
parallelism of
visual axis, slight
widening of left
PFH

80. TYPE III DRS
 Marked limitation
of adduction and
abduction

 Narrowing of PFH
on adduction and
abduction


81. BROWN’S SYNDROME
 Aka superior oblique tendon sheath syndrome
 Apparent/pseudo paralysis of inferior oblique
muscle, limitation of elevation in adduction
 Due to restriction of IO action by an overly taut
superior oblique tendon of the same eye
 Widening of PFH on adduction
 Few may have in primary position
responsible for head posture
hypotropia

83. AHP in BROWN’S SYNDROME
 Head tilt to affected side
 Face turn to contralateral side
 Chin elevation
head posture confined to chin elevation if
syndrome is bilateral

84. GRAVE’S OPHTHALMOPATHY
 May be associated with hyper, hypo or euthyroidism
 Circulating thyroglobulins, and anti thyroglobulin
immune complex bind to EOM ophthalmopathy
in sequence of I’M SLOW
Inferior rectus
Medial rectus
Superior
rectus
Lateral rectus
Oblique muscles

85.  Common ocular mobility defect is U/L elevator
deficiency followed by defective abduction
 eye is hypotropic and esotropic
Chin
elevation
with or
without Face
turn to same
side

87. FIBROSIS OF EOMs
 Group of congenital anomalies with restrictions of
EOMs
 Due to replacement of muscle fibres by the fibrous
tissue
 Ranges from isolated fibrosis to B/L involvement of
all EOMs

88. GENERALIZED FIBROSIS SYNDROME
 Fibrosis of all EOMs
no elevation or depression
little or no horizontal movement
 Bilateral ptosis
 AHP : backward head tilt with chin elevated

89. STRABISMUS FIXUS
 Rare disorder , commonly with marked esotropia
associated with extreme tightness of MR muscle
 Most patient adopt chin elevation

90. VERTICALLY INCOMITANTHORIZONTAL
HETEROTROPIA
 Aka alphabet patterns tropias
 Horizontal deviation that change in magnitude with
upgaze and downgaze

91. A-PATTERN HETEROTROPIA
 Increasing convergence in upgaze and increasing
divergence in downgaze
 For A-pattern esotropes,to make eyes relatively
convergent in downgaze,the chin is elevated
 For A-pattern exotropes,to make eyes relatively
divergent in upgaze,the chin is depressed

93. V-PATTERN HETEROTROPIA
 Increasing convergence in downgaze and increasing
divergence in upgaze
 For V-pattern exotropes,to make eyes relatively
convergent in upgaze,the chin is elevated
 For V-pattern esotropes,to make eyes relatively
divergent in downgaze,the chin is depressed

95. INFANTILE ESOTROPIA
 Manifest eso deviation with an onset between birth
and 6 months of age
 Etiology unknown
 Head & face tilt towards the shoulder of the fixating
eye
 In some cases AHP associated with ML nystagmus
 Pt turn head towards the side of the fixing eyewhich gets
optimal visual acuity in the position of adduction

96.  Congenital esotropia with
manifest nystagmus,
 left eye fixing in
adduction, head turned
towards left, the direction
of the left fixing eye ; pre
op
 Post-op picture after bi-
lateral medial rectus
recession
 no head turn

97. REFERENCES

98. SPECIAL THANKS TO :
Sanjeev Bhattarai sir