Paralytic strabismus is caused by motor deficiency of one or more extraocular muscles due to neurogenic, myogenic or junctional disorders. Common types include third, fourth and sixth nerve palsies which result in limited eye movements and misalignment. Third nerve palsy affects elevation, adduction and depression while fourth and sixth nerve palsies impact specific individual muscles. Investigation involves assessment of eye alignment, movements, diplopia and visual acuity to localize the lesion. Management depends on severity but may include occlusion therapy, prisms or strabismus surgery.

1. PARALYTIC STRABISMUS
K.RAJESWARI
M.OPTOM – 1ST YEAR
151141002

2. INTRODUCTION
•There are 6 extra ocular muscles – 4 rectus muscles, 2
oblique muscles
Superior Recti Inferior Recti
Medial Recti Lateral recti
Inferior oblique Superior Oblique
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3. ORIGIN
AND
INSERATION
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MR
LR
IR
SR
ANNULUS OF
ZINN
SCLERA @
5 . 5mm
OCCULOMOTOR
ANNULUS OF
ZINN
SCLERA @
6 . 9mm
TROCLEAR
ANNULUS OF
ZINN
SCLERA @
6 . 5mm
OCCULOMOTOR
ANNULUS OF
ZINN
SCLERA @
7 . 7mm
OCCULOMOTOR

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SO
IO
LPS
SPHENOID
BONE
POSTIOSUPERIOR
QUADRENT
ABDUSENT
ORBITAL
FLOOR
POSTIOINFERIOR
QUADRENT
OCCULOMOTOR
SPHENOID
BONE
SUPRA TARSAL
PLATE
OCCULOMOTOR

6. MUSCLE
PRIMARY
ACTION
SECONDARY
ACTION
TERTIARY
ACTION
MEDIAL RECTUS Adduction -- --
SUPERIORRECTUS Elevation Intortion Adduction
INFERIORRECTUS Depression Extortion Adduction
INFERIOROBLIQUE Extorsion Elevation Abduction
SUPERIOROBLIQUE Intorsion Depression Abduction
LATERAL RECTUS Abduction ---- ----
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7. TERMS
Agonist
Prime mover
Antagonist Muscle Having The
OpposedAction
Synergist
Muscle Having The Same
Actions
contraction&Relaxation
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8. Ipsilateral On The Same Side
Contralateral On The Opposite Side7
Contracture
IncreasedResistanceAgainst
Passive Stretching Of The
Muscle, Loss Of Elasticity
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9. Muscle Ipselateral
Antagonist
Contralateral
synergist
Contralateral
antagonist
RMR RLR LLR LMR
RLR RMR LMR LLR
RSR RIR LIO LSO
RIR RSR LSO LIO
RIO RSO LSR LIR
RSO RIO LIR LSR
Contralateral
antagonist
Contralateral
Synergist
Ipselateral antagonist Muscle
For right eye read from the top
For left eye read from the bottom
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10. An equal and simultaneous innervation flows from the
brain to a pair of muscles of both eyes (yoke muscles)
which contract simultaneously in different binocular
movements
E.g. Equal and simultaneous innervation flows to:
1. RLR and LMR muscles during dextroversion
2. RSR and LIO muscles during dextroelevation
Hering’s Law of
Equal
Innervation
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11. Whenever an agonist receives an impulse to contract, an
equivalent inhibitory impulse is sent to its antagonist, which
relaxes
e.g. during dextroversion , an increased innervational flow to
the RLR and LMR is accompanied by decreased flow to the
RMR and LLR muscle.
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12. Under action of the primary muscle
Over action of the contralateral
synergist
Over action of the ipsilateral
antagonist
Under action of the contralateral
antagonist
Overaction of the ipsilateral
synergist??
Sequelae
Ocular
Muscle
Palsy
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13. PARALYTIC
STRABISMUS
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14. Due to motor deficiency of one or a group of extra
ocular muscles
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15. SIGNS
• Eyes that do not align in the same direction
• Uncoordinated eye movements (eyes do not move together)
• Reduced of vision
• Reduced depth perception
• Compensatory HP
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16. SYMPTOMS:
1. Limitation of ocular movements
2. Sudden onset ocular deviation
3. Diplopia
4. Confusion
5. Nausea , vertigo
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17. CLASSIFICATION
NEUROGENIC JUNCTION MYOGENIC
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18. NEUROGENIC
• Localisation
• Supra nuclear
• Nuclear
• Internuclear
• Infra nuclear
Nerves
• Oculomotor nerve (III CN)
• Trochlear nerve (IV CN)
• Abducens nerve (VI CN)
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19. •Etiology:
•Congenital hypoplasia or absence of
nucleus: third and sixth cranial nerve
palsies.
•Inflammatory lesions: encephalitis,
meningitis, Neuro syphilis, peripheral
neuritis (viral),infectious lesions of
cavernous sinus and orbit.
•Neoplastic lesions – brain tumors
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20. •Vascular lesions: HTN, DM and
atherosclerosis. Haemorrhage,
thrombosis, embolism, aneurysms or
vascular occlusions
•Traumatic lesions: head injury
•Toxic lesions: CO poisoning, -OH
neuropathy.
•Demyelinating lesions: multiple sclerosis
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21. THIRD
NERVE
PALSY
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22. •The III nerve divides into two branches.
• The superior branch supplies the LPS and SR
•The inferior branch supplies the MR, IR and
IO muscles.
•A complete lesion deficit of elevation,
adduction and depression.
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23. LOCALIZATIONOF LESION
Nuclear:
•Bilateral ptosis
 Internuclear
• Ophthalmoplegia
 Infranuclear
• partial or complete impairment of pupillary
reactions
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24. AETIOLOGY
Pupil-sparing causes tend to relate to ischaemic microvascular disease
(and rarely, cavernous sinus syndrome).
Pupil-involving disease usually arises as a result of an aneurysm but
can also occur as a result of
• tumour,
• trauma,
• pituitary apoplexy,
• herpes zoster and
• leukaemia.
Children may exhibit third nerve palsy as part of an ophthalmoplegic
migraine.
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25. INVESTIGATIONS
1. VISUAL ACUITY:
a) It is necessary to lift the ptotic lid to evaluate visual acuity.
b) May be reduced due to mydriasis, particularly for near visual
acuity
2. COVER TEST
a) An exo- and hypo-deviation is present
3. OCULAR MOTILITY
a) be limited elevation, depression and adduction,
b) complete or partial limitations
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26. 4. Hess chart
a. The affected eye will show a markedly constricted field
b. The other eye demonstrates overaction of its muscles
5. Diplopia
a) There will be constant diplopia unless complete ptosis is present and
blocks the vision of the affected eye
6. Convergence
a) This will be absent if the medial rectus muscle is paralysed
7. Binocular function
a) This is usually absent unless the III nerve paresis is mild and partial
8. Accommodation
a) Due pupillary dilatation, the accommodation will be defective
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27. ABERRANT REGENERATION
•Change in the regrowth of damaged nerve fibres
following complete or severe third nerve palsy
•It is liable to occur when either trauma or an aneurysm
has caused the lesion
•May occur from weeks to months after the onset of the
III nerve paresis
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28. CYCLIC OCULOMOTOR PALSY
•This rare condition is usually congenital and
unilateral in origin
•It is often associated with some degree of ptosis.
•Acquired cyclic ocular motor palsy may occur
following irradiation of the skull base and is
similar to ocular neuro-myotonia
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29. Contd…
•The condition is described as having cyclical
fluctuation in two phases:
Paralytic phase: There is a partial III nerve palsy.
Miotic phase: There is convergence, lid retraction,
accommodation and pupil constriction
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30. FOURTH
NERVE
PALSY
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31. •The IV cranial nerve supplies the superior oblique
muscle only.
• Any lesion affecting the nerve may result in
difficulties of
•depression,
•incyclorotation and
•abduction of the eye
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32. LOCATIONOF LESION
•Fourth nerve palsy may be due to lesions in the
nucleus or fascicular lesions of the midbrain.
• It can be difficult to differentially diagnose nuclear
and fascicular lesions as the IV nerves crosses
immediately after exiting the nuclei and exit the
•dorsal midbrain after a very short intra-midbrain
course.
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33. PRESENTATION:
•Binocular vertical diplopia,
•difficulty in reading and
•the sense that ------- things appear to be tilted.
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34. •There is often facial asymmetry
consisting of shallowing of the
midfacial region between the lateral canthus
and the edge of the mouth
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35. ETIOLOGY
•Trauma,
•Vasculopathy (often related to diabetes and
hypertension) and
•Demyelinating disease.
•This may also be congenital or
•idiopathic
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36. INVESTIGATIONS
1.COVER TEST
The test is performed with and without the abnormal
head posture for comparison.
A latent deviation exists if a compensatory abnormal
head posture is adopted.
2.OCULAR MOTILITY (sequelae)
The primary under action of the affected superior
oblique muscle.
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37. 3. CONVERGENCE :
• This may be reduced, either due to convergence insufficiency or
the vertical deviation
4. DIPLOPIA
• greater degree of diplopia on near testing when looking down
• usually uncrossed
5. Torsion Diagnostic prisms
• Excyclotorsion is frequently present.
• Fresnel prisms may be used temporarily to correct the angle of
deviation.
• If the prism releves abnormal head posture, then the indication is
that the IV nerve was responsible for the abnormal head posture
rather than a non-ocular cause.
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38. SIXTH
NERVE
PALSY
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39. •The VI cranial nerve supplies the
lateral rectus muscle only.
•A lesion affecting the nerve will
result in defective abduction of the
eye
•Presentation:Horizontal diplopia
(D>N)
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40. AETIOLOGY
• Trauma,
• Vascular insults and
• inflammation.
• Palsy secondary to raised intracranial pressure is regarded as
a typical false localising sign.
• Other causes have included post-operative complications,
viral infection, multiple sclerosis and otitis
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41. CONTD…
•Congenital
• Following birth
trauma
• Hereditary
• Infection (maternal)
• Failure of lateral
rectus development
• Young adults:
• Trauma
• Space-occupying lesions
• Post-viral inflammatio
• Multiple sclerosis
• High myopia
• – Ophthalmoplegic
migraine
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42. INVESTIGATION
1. VISUAL ACUITY
• This may be reduced if the affected eye fails to fixate due
to the presence of deviation.
2. ABNORMAL HEAD POSTURE
• The face is turned towards the affected side
3. Cover test
• An eso-deviation is present (D>N)
• with and without an abnormal head posture.
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43. 4. Ocular motility
•The primary underaction of the lateral
rectus results.
5.Binocular function
•This is often retained in the presence of an
abnormal head posture
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44. MYOGENIC
• ETIOLOGY:
• Congenital - Absence ,hypoplasia mal insertion or
muscular facial anomalies
• Traumatic laceration, disinertion
• Inflammatory - Myositis (viral) , influenza, measles.
• Myopathies: These include thyroid myopathy, carcinomatous
myopathy, Progressive external Opthalmoplegia
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45. SINGLE MUSCLE PALSY
1. Medial rectus
• This produces an exo-deviation, which is greater for near
fixation.
2. Inferior rectus:
• This produces hyper- and exo-deviation
3. Superior rectus:
• This is often bilateral and may present with a V exo
pattern.
4. Inferior oblique:
• This is a feature of an A eso pattern
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46. DIFFERENTIAL DIAGNOSIS OF SINGLE MUSCLE
PALSIES
• MR palsy
Atypical Duane’s retraction syndrome
Uni/bilateral inter nuclear ophthalmoplegia
• IR palsy
Myogenic (myasthenia gravis)
Mechanical limitation (thyroid eye disease)
Trauma (blowout fracture)
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47. •IO palsy
Brown’s syndrome
•SR palsy
Trauma (blowout fracture)
Mechanical limitation (thyroid eye
disease
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48. DOUBLE ELEVATOR PALSY
•This often has a congenital origin and is
presumed to be caused by a supra nuclear
defect.
•The superior rectus and inferior oblique muscles
of the same eye are affected.
•Bell’s phenomenon is usually present.
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49. DIFFERENTIAL DIAGNOSIS DOUBLE ELEVATOR
PALSY
•The following conditions should be differentiated from
double elevator palsy as they will have a positive forced
duction test:
• Blowout fracture
• Thyroid eye disease
• Brown’s syndrome
• Congenital fibrosis of the inferior rectus muscle
• General fibrosis syndrome
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50. MULTIPLE NERVE PALSIES
Presentation:
oThere may be a combination of unilateral III, IV and VI
cranial nerves
oFacial pain corresponding to one or more branches of the
fifth cranial nerve,
oPtosis and small pupil (Horner's syndrome) or a dilated
pupil if the third cranial nerve is affected.
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51. ETIOLOGY:
• Tumours within the cavernous sinus (primary or metastatic).
• Intracavernous aneurysm.
• Mucormycosis (particularly in those patients with uncontrolled
diabetes and in immuno compromised patients).
• Pituitary apoplexy.
• Herpes zoster.
• Cavernous sinus thrombosis.
• Tolosa-Hunt syndrome.
• Rare causes: sarcoidosis, Wegener's granulomatosis, tuberculosi
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52. OTHER
IMPORTANT
TESTS…
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53. FORCED DUCTION TEST
To differentiate the palsy and restrictions due to mechanical factors
• Anesthesia
• Supine position
• Speculum to hold the lids
• Forceps without teeth kept in the right angle to the deviation
• Grab the globe
• Passive rotation of the globe
FDT +VE – Mechanical restrictions (resistance)
FDT –VE – Muscle palsy (no resistance)
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54. PARK'STHREE-STEP TEST
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? Which eye is hyper deviated in primary gaze
? Is the vertical deviation greater in right gaze or left gaze
? Is the vertical deviation greater with right head tilt or left
head tilt.
LIMITATIOS
• only for vertical deviations
• Cannot tested for neuromyopathic conditions.

55. HESS CHARTING
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56. DIPLOPIA CHARTING
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To assess Extra ocular
muscle paresis.
Disadvantages:
• Qualitative
• Requires co-operatio and
intelligent patient
• Cannot do for colour blind
patients

57. POST POINTING TEST
• A test of the integrity of vestibular system.
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58. LESS CHARTING
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59. NEUROMUSCULAR JUNCTION LESION
It includes myasthenia gravis:
A rare chronic autoimmune disease marked by
muscular weakness without atrophy, and caused by a
defect in the action of acetylcholine at neuromuscular
junctions.
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60. differences Paralytic Non paralytic
Age of onset Usually late Usually early childhood
Type of onset Sudden Gradual, sudden
manifestation
Precipitating
events
Usually head injury , systemic
illness
Rarely present. Even if
present no cause effect
relationship
Associated
neurological
signs
May be present None
Comitance May develop in late stages Usually present (except
in extreme gazes)
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61. REFERENCES
1) BINOCULAR VISION & STRABISMUS –GK VON NOORDEN
2) CLINICAL MANGEMENT OF STRABISMUS- ELEZABETH
E.CALAROSSA & MICHAEL W. ROUSE
3) AAO- SECTION: PEDIATRIC OPHTHALMOLOGY & STRABISMUS
4) STRABISMUS SIMPLIFIED- PRADEEP SHARMA
5) PRACTICAL ORTHOPTICS IN THE TREATMENT OF SQUINT-
LYLE AND JACKSON’S.
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