Be the master in strabismus

1. STRABISMUS

2. EXTRAOCULAR MUSCLES AND
OCULAR MOTILITY

4. EMBRYOLOGICAL DEVELOPMENT
3 distinct masses of Primordial cranial mesoderm
Receive input from 3 cranial nerve as early as 1st month of gestation
Premandibular condensation gives rise to eye muslces innervated by
third cranial nerve.
LR and SO from Maxillomandibular mesoderm
LR and SO lie as B/l masses close to stalk (6 weeks )
4 Recti differentiate at( 7 weeks )
LPS differentiates from SR in its medial part at 8 weeks .

5. Extraocular
muscles
Voluntary
muscles
Involuntary
muscles
Superior tarsal muscle
Inferior tarsal muscle
LPS
Recti muscles
Oblique muscles

6. RECTI MUSCLES - origin
• ANNULUS OF ZINN -
common tendinous ring
• Attachments
• Forms a muscle cone

7. RECTI MUSCLES - origin
Superior Rectus
Lateral Rectus
Medial Rectus
Inferior Rectus

8. RECTI MUSCLES - Insertion
 Inserted into sclera
 In front of equator
• Distance from cornea 7.7mm
MR = 5.5mm behind
nasal limbus
IR = 6.5mm behind
inferior limbus
LR = 6.9mm behind
temporal limbus
SR = 7.7mm behind
superior limbus
6.9 mm 5.5mm
6.5 mm

9. SUPERIOR OBLIQUE - origin
Superior Oblique
Origin: body of sphenoid, Superomedial to Optic Nerve

10. SUPERIOR OBLIQUE – Insertion
Passes forward through the trochlea and then reflect backwards
and laterally to insert to the posterior upper temporal quadrant of
the globe behind the equator

11. INFERIOR OBLIQUE - origin
Inferior Oblique
Origin :from a small depression in the orbital surface of maxilla just behind the
orbital rim lateral to the lacrimal fossa.

12. INFERIOR OBLIQUE – Insertion
Behind the equator on sclera in posterior lower
temporal quadrant of globe.

13. Spiral of tillaux
 Imaginary line joining
the insertions of the 4
recti and is an important
anatomical landmark
when performing
surgery.
 The insertions are
located progressively
further away from the
limbus in a spiral pattern.
 the medial rectus
insertion is closest .
 Superior rectus is
farthest.

14. NERVE SUPPLY
Abducens nerve supplies Lateral
Rectus muscle
Trochlear nerve supplies Superior
Oblique muscle
Superior branch of oculomotor nerve
supplies Superior Rectus muscle,and
Levator Palpebrae Superioris muscle
Inferior branch of oculomotor nerve
supplies Inferior and Medial recti
,Inferior Oblique

15. BLOOD SUPPLY
Extraocular muscles Blood supply
Superior rectus (SR) -Superior muscular branch of ophthalmic artery and 2
anterior Ciliary artery
Inferior rectus (IR) -The inferior muscular branch of ophthalmic artery
and infraorbital artery, 2 anterior Ciliary vessels
Medial rectus (MR) -The medial rectus is supplied by the inferior
muscular branch of ophthalmic artery and 2 anterior
Ciliary arteries.
Lateral rectus (LR) -The lacrimal artery (the only rectus muscle with a
single blood supply)
Superior oblique (SO) -The superior muscular branch of ophthalmic artery
supply blood
Inferior oblique (IO) -The inferior branch of ophthalmic artery and
infraorbital artery

16. Dept. of Ophthalmology, JNMC, Belagavi
Venous drainage of EOM
The venous drainage of the extraocular muscles is via the•
superior and inferior orbital veins to ophthalmic veins
vein
sinus
inferior
orbital vein
Inferior
ophthalmic
vein
Cavernous
Superior
ophthalmic
Clinical correlates:
Secondary
Perimuscular
infection following
EOM trauma can
spread infection to
cavernous sinus .
Cavernous vascular
disease can present
as opthalmoplegia
and proptosis
Superior
orbital vein
Anterior ciliary
vein

17. Action of extraocular
muscles
 Rotation around centre of rotation
 Centre of rotation lies 12/13 mm behind
cornea.
 3 types of rotation:
Muscles Primary action Secondary action Tertiary action
MR Adduction
LR Abduction
SR Elevation Intorsion Adduction
IR Depression Extorsion Adduction
SO Intorsion Depression Abduction
IO Extorsion Elevation Abduction

18. Diagnostic positions of gaze:-9
1 Primary position of Gaze:assumed
by eyes when fixating a distant
object with head erect.
4 Secondary position
4 Tertiary position
6 cardinal positions :- to test 12
EOM in their main field of action

19. OCULAR MOVEMENTS
1.Monocular
Adduction
Abduction
Supraduction
Infraduction
Incycloduction
Excycloduction
movements(ductions)
Tested by occluding the fellow eye and asking the patient to
follow a target in each direction of gaze
Listing Plane and Axes of Fick

20. OCULAR MOVEMENTS
2.Binocular
•Versions
-Dextroversion
-Levoversion
-Supraversion
-Infraversion
-Dextroelevation
-Dextrodepression
-Levoelevation
-Levodepression
-Dextrocycloversion
-Levocycloversion
movements
Tested by asking the patient to follow the target with both eyes

21. OCULAR MOVEMENTS
Vergence:
-Disjugate, synchronous and symmetric movements of the two eyes in opposite
direction
Disjugate: Rotation of the two eye in opposite direction (eg; convergence and
divergence)
Synchronous: Occurs at a same time
Symmetric: Exactly like another
•
Convergence (simultaneous movement nasally)
simultaneous Contraction of medial recti
 Divergence (simultaneous temporal movement)
Simultaneous contraction of lateral recti

22. Agonist,Antagonist,synergists and yoke muscles
Agonist :a muscle producing movement
on contraction
Antagonist muscles : A muscle producing
a movement in the
direction opposite produced by agonist.
• Synergists muscles :Two muscles
having similar primary action in the same
eye.
Contralateral antagonist:these are pair of
muscle one from each eye having
opposite action.
Yoke muscles(contralateral synergist)
:pair of Muscles one from each eye that
conracts simultaneously during version.
•

23. .
FUNDAMENTAL LAWS GOVERNING OCULAR MOTILITY
It states equal and simultaneous innervation
flow from brain to pair of muscle which
contract simultaneously in different
binocular movement. In paralytic squint
secondary deviation is more than primary
deviation.
1.Hering ’s law of equal innervation 2.Sherrington law of reciprocal
innervation
Increased innervation to an EOM is
accompanied by reciprocal decrease in
innervation to its antagonist.
The antagonist relaxes as the agonist contracts

24. PHYSIOLOGICAL REGULATORY
MECHANISM OF EYE MOVEMENT &
BINOCULAR SINGLE VISION

25. SUPRANUCLEAR CONTROL OF EYE
MOVEMENT
• It keeps the two eyes yoked together so that
image is simultaneously held on both fovea.
Supranuclear eye movement systems include:
1.saccadic system
2.smooth pursuit system
3.vergence system
4.vestibular system
5.optokinetic system
6.position maintenance systems

26. 1.SACCADIC SYSTEM:
sudden,jerky conjugate eye movement,that
occur as the gaze shifts from one object to
another. Though normally voluntary, saccades
may be involuntarily aroused by peripheral,
visual or auditory stimuli.
2.SMOOTH PURSUIT SYSTEM:
Tracking movement of the eye as they
follow moving objects.when the velocity of
moving object is more, this is replaced by small
saccade(catchup saccades)

27. 3.VERGENCE SYSTEM:Allow focusing of an
object which moves from or towards the
observer or when visual fixation shifts from one
object to another at a difference distance.
4.VESTIBULAR SYSTEM:
Effective in compensating for the effects of
head movements in disturbing visual fixation
through vestibular system.

28. • 5.OPTOKINEIC SYSTEM:-It helps to hold the
images of the seen world steady on the retinae
during sustained head rotation. This becomes
operative when vestibular system fails after 30
sec.
6.POSITION MAINTENANCE SYSTEM: To maintain
specific gaze position by rapid micromovements
called ‘flicks’ and slow micromovements called
‘drifts’.

29. BINOCULAR SINGLE VISION
• DEFINITION:
When a normal individual fixes his visual
attention on an object of regard , the image is
formed on the fovea of both the eyes seperately;
but the individual perceives a single image.This is
called binocular single vision.
It is acquired during first 6 months and
completed during first few years.

30. • Important milestones:
-at birth no central fixation.
-By 1st month fixation reflex starts.
-By 6th month macular stereopsis and
accomodation reflex is fully developed.
-By 6 years full Va and binocular single vision
is obtained.
PREREQUISITIES FOR DEV OF BINOCULAR
SINGLE VISION:
1. straight eyes
2.reasonably clear vision
3.abilitty of visual cortex.

32. • ANOMALIES OF BINOCULAR VISION:
1.Supression
2.Amblyopia
3.Abnormal retinal correspondence
4.Diplopia

33. AMBLYOPIA
• DEFINITION:
Amblyopia refers to a partial loss of vision in
one or both the eyes, in the absence of any
organic disease of ocular media , retina and
visual pathway.
PATHOGENESIS:
produced by certain amblyopic factors
operating during critical period of visual
development.Those include
1.visual deprivation
2.light deprivation.
3.abnormal binocular interaction.

34. • TYPES:
1.Strabismus amblyopia
2.Stimulus deprivation amblyopia.
3.Anisometropic amblyopia
4.Isoametropic amblyopia
5.Meridional amblyopia.

35. • CLINICAL FEATURES:
1.Visual acuity is reduced
2. Effect of neutral density filter will be
improved in amblyopia.
3.Crowding phenomenon is present
4. Fixation pattern may be central or
eccentric.
5.Color vision is normal, may be affected in
deep amblyopic with vision below6/36.

36. • TREATMENT:
OCCLUTION THERAPY i.e, occlusion of
sound eye to force use of amblyopic eye.
However, before the occlusion therapy is
started, it should be ensured that:
1.Opacity , if any should be removed.
2.Refractive error if any should be
corrected.

37. • Simplified schedule for occlusion therapy
depending upon on the age is as below
Upto 2 years should be done in 2:1, i.e, 2
days in sound eye and one day in amblyopic
eye.
At the age of 3, 3:1.
At the age of 4, 4:1.
At the age of 5, 5:1.
At the age of 6, 6:1.
Duration of occlusion should be until the
visual acuity develops fully, or there is no
further improvement of vision in 3 months.

39. DIPLOPIA
Diplopia occurs due to
formation of image on two
dissimilar points of two
retinae.

40. • CAUSES OF BINOCULAR DIPLOPIA:
1.Paralysis or paresis of the extraocular
muscles.
2.Displacement of one eye ball.
3.Mechanical restriction of ocular movement.
4.Deviation of ray of light in one eye.
5.Anisometropia.

41. • TYPES:
1.Uncrossed diplopia
In uncrossed diplopia the false image
is on the same side as deviation. It occurs in
convergent squint.
2.Crossed diplopia:
In crossed diplopia the false image is
seen on the opposite side.It occurs in
divergent squint.

42. • UNIOCULAR DIPLOPIA:
It’s not an anomaly of binocular vision. In
uniocular diplopia an object appears double from
the affected eye even when the normal eye is
closed.
CAUSES:
1.Subluxated clear lens.
2.Subluxated intraocular lens.
3.Double pupil.
4.Incipient cataract.
5.Keratoconus.
TREATMENT:
Treat the causative disease. Temporary relief
can be obtained by occluding the affected eye.

43. SUPRESSION
• 1.It is a temporary active cortical inhibition of
the image of an object formed on the retina of
the squinting eye .
2.This occurs only in binocular vision.
3.However, when the fixating eye is covered,
the squinting eye fixes(i.e, supression
disappears).
TESTS TO DETECT SUPRESSION:
1.Worth’s 4-dot test.
2.Four Dioptre base out prism test.
3.Red glass test.
4.Synoptophore test

45. ABNORMAL RETINAL
CORRESPONDENCE
• 1.When squint develops, patient may have either
diplopia or confusion.
2.To avoid these,sometimes there occurs an
active cortical adjustment in directional values of
two retinae.
3. In this state fovea of the normal eye and an
extrafoveal point on the retina of the squinting
eye acquire a common visual direction direction
i.e, become corresponding points.
4.This condition is called abnormal retinal
correspondence and child gets crude type of
binocular vision.

46. • TEST TO DETECT ARC:
1.Worth’s four dot test
2.Titmus stereo test
3.Bagolini striated glass test
4.After image test
5.Synoptophore test.

47. Apparent and Latent
Strabismus

48. Strabismus
•Also known as squint/ cross-eye.
•A misalignment of the visual axes of the two eyes is
called strabismus.

49. Types of strabismus
Strabismus
Apparent
strabismus
Latent
strabismus
Manifest
strabismus
Concomitant
strabismus
Incomitant
strabismus

50. Apparent/ Pseudostrabismus
•In apparent strabismus, the visual axes are in fact
parallel, but the eyes seem to have a squint.
•Its is of two types:
1. Pseudoesotropia or apparent convergent squint.
2. Pseudoexotropia or apparent divergent squint.

51. Association
•Pseudoesotropia may be associated with : prominent
epicanthal fold (which covers the normally visible nasal
aspect of the globe and gives a false impression of
esotropia).

52. •Pseudoexotropia may be associated with:
hypertelorism, a condition of wide separation of
the two eyes.

53. Latent strabismus/ Heterophoria
•Is a condition in which the tendency of the eyes to
deviate is kept latent by fusion. Therefore, when the
influence of fusion is removed the visual axis of one
eye deviates away.
•Orthophoria is a condition of perfect aligment of the
two eyes which is maintained even after the
removal of influence of fusion.

54. LATENT
SQUINT
Esophoria
Exophoria
Hyperphoria
and Hypophoria
Cyclophoria
Convergence
excess
Divergence
weakness
Non- specific
type
Convergence
weakness
Divergence
excess
Non-
specific type

55. Etiology
A. Anatomical factors:
•Orbital asymmetry
•Abnormal interpupillary distance(IPD):
1. Wide IPD: exophoria
2. Small IPD: esophoria
•Extraocular muscles:
1.Faulty insertion
2.Mild weakness
3.Abnormal innervation
•Anatomical variation in the position of the macula in
relation to the optical axis of the eye.

56. B. Physiological factors
• Age : younger age = esophoria
older age = exophoria
• Role of accomodation and convergence:
1. Increased accomodation and excessive use of convergence:
esophoria
2. decreased accomodation and decrease use of convergence:
exophoria
• Dissociation factor: prolonged use of one eye may result in
exophoria ( as in case of persons working with uniocular
microscope/ magnifying glass).

57. Factors predisposing to
decompensation
•Inadequate of fusional reserve.
•General debility and lowered vitality.
•Psychosis, neurosis, and mental stress.
•Precision of job, and
•Advancing age.

58. Symptoms of heterophoria
•Depending upon the symptoms, heterophoria can
be divided into compensated and decompensated
heterophoria.
•In compensated heterophoria, no subjective
symptoms are present.
•In decompensated heterophoria, the symptoms
which will be present are:

59. Cause symptoms
Muscle fatigue Headache,
Eyeache,
Photophobia,
Difficulty in changing the focus,
Failure to maintain
binocular vision
Blurring of vision,
Intermittent diplopia,
Intermittent squint without diiplopia,
Defective postural
sensation
Difficulty in judgement of positions
of moving objects.

60. CCCC
CONCOMITANT
STRABISMUS

61. • Type of manifest squint.
• Amount of deviation in the squinting
eye remains constant.
• Limitation of ocular movement is absent.

62. Etiology
Binocular vision and coordination of ocular movements
Are acquired in the early childhood
The process starts at 3-6 months and Is completed upto
5-6 years
Obstacle to the develepoment CONCOMITANT SQUINT

63. Sensory obstacle
•Refractive error
•Prolonged use of incorrect spectacles
•Anisometropia
•Corneal opacities
•Lenticular opacities
•Diseases of macula
•Optic atrophy
•Obstruction in the pupillary area due to congenital
ptosis.

64. Motor obstacles
•Abnormalities of the orbit
•Abnormalities of extraocular muscle such as faulty
insertion, faulty innervation and mild paresis
•Abnormalities of accommodation, convergence, and
AC/A ratio.

65. Central obstacles
•Deficient development of fusion faculty
•Abnormalities of cortical control of ocular
movements in mental trauma, and hyperexcitabilty
of the central nervous system during teething.

68. TTYPES

76. INCOMITANT SQUINT

77. Definition & Types
•Type of Manifest squint in which Amount of
deviation varies in different directions of gaze.
•Types –
1. Paralytic squint
2. A & V pattern heterotropias
3. Restrictive squint

78. Paralytic Squint
Ocular Deviation –
Complete or incomplete
paralysis of 1 or more
extraocular muscle
Etiology –
1. Neuromuscular Junction
Lesion – Myasthenia Gravis
R L

79. 2.Neurogenic lesions
•Congenital
•Inflammatory
•Neoplastic
•Vascular
•Traumatic
•Toxic
•Demyelinating
3.Myogenic lesions
•Congenital
•Traumatic
•Inflammatory
•Myopathies
ETIOLOGY
(contd)

80. Symptoms -
1. Diplopia- Main Symptom
• More marked in field of
action of paralysed muscle
• Formation of image on
dissimilar points on the 2
retina.
• False image is less distinct
than true image.
• Convergent squint –
uncrossed
• Divergent squint – crossed
Uncrossed
Crossed

81. 2. Confusion- Formation
of 2 different objects on
corresponding points of
retina
3. Nausea and vomiting
4. Ocular deviation
Confusion

82. Signs
1. Primary Deviation –
Deviation of affected eye
away from the action of the
paralysed muscle
2. Secondary Deviation –
Deviation of normal eye seen
under cover when the patient
fixates with the squinting eye.
Secondary > Primary ( WHY ?)
L
R

83. 3.Restriction of ocular
movement
4.Compensatory head
posture – Avoid diplopia
and confusion.
•Head is turned towards
direction of action of
paralysed muscle.
5.False projection or
orientation.

84. Pathological sequalae in extraocular
palsies
LR

85. Third Nerve Palsy
Features
•Ptosis
•Deviation
•Ocular movements
•Pupil
•Accommodation
•Crossed diplopia
•Head posture

86. A-V pattern heterotropia
•Amount of deviation in squinting eyes varies - > 10
and 15 degrees, respectively, in upward and
downward gaze
•Etiology
1. Oblique muscle dysfunction
2. Horizontal/Vertical rectus muscle dysfunction

87. A pattern
Amount of deviation –
A esotropia - Upward gaze
Downward gaze
A exotropia - Upward gaze
Downward Gaze

88. V Pattern
Amount of deviation –
V esotropia - Upward
gaze Downward gaze
V exotropia - Upward
Gaze Downward Gaze

89. Restrictive squint
•Movement of extraocular muscle is restricted.
•Characteristic features –
1. Smaller ocular deviation
2. Positive forced duction test
Causes
•Duaane retraction syndrome
•Brown superior oblique tendon sheath syndrome
•Strabismus fixus
•Dysarthroid ophthalmology
•Blow out fracture of orbit

90. Duane’s Retraction syndrome -
• Congenital ocular motility defect
• Paradoxical innervation of lateral/medial rectus or
both
• Features –
1.Limitation of adduction/abduction or both
2.Narrowing of palpebral fissure on attempted
adduction
3.Eye in primary position- ortho/eso/exotropic

92. Distance/ Near or both
HISTORY
Intermittent/ Constant
Which eye: One/ Both/ Alternating
Mode of Onset: Sudden/ Gradual
Duration
Age of onset
H/o trauma
Diplopia

93. HISTORY
A/s of tingling, numbness
A/s of raised ICP
H/o neurological symptoms
Precipitating factors
Old photographs

94. Previous ocular hx: Refractive errors, Refractive prescriptions and its
compliance
Medical hx: General development ( development problems- cerebral palsy high
risk), recent illness, systemic illness ( DM, HTN, Neurological problems)
Birth hx: Period of gestation, birth weight, problem in utero, during
delivery or in neonatal period, developmental milestone
Family hx: Squint, Refractive error
Treatment hx: h/o of previous squint surgery, occlusive therapies

95. Clinical Evaluation Sequence
Evaluation of Motor Status
Measurement of deviation
Test for Diplopia
Test for steropsis
Evaluation of sensory status
Visual Acuity

96. VISUAL ACUITY
Preverbal children
• Fixation and following
• Comparison between behaviours of two eyes
• Fixation behaviour
• Rotation test
• Preferential looking
a) Teller acuity cards
b) Cardiff acuity cards

97. Visual acuity tests in verbal children
Kay single picture Multiple pictures
Sheridan-Gardiner Sonksen-Silver
At age 3 years (matching tests)
At age 2 years (naming pictures)

98. Visual acuity for school going children and adults
Snellen’s chart
Landolt C chart
Illiterate E chart

99. Refraction:
: It may be responsible for symptoms
: Or for deviation itself
Examination of anterior and posterior segment
: Lid problems like ptosis, lagophthalmos
: Media opacities
Pupillary reflexes
Fundoscopy: To exclude ocular pathologies such as macular scaring,
optic disc hypoplasia, retinoblastoma

100. Evaluation of sensory status
Worth four dot test
This is a dissociation test which can be used with both
distance and near fixation and differentiates the
following:
BSV, ARC and Suppression
Procedure:
1. The patient wears a red lens in front of the right
eye, which filters out all colours except red, and a
green lens in front of the left eye which will filter
out all colours except green
2. The patient then views a box with four lights: one
red, two green and one white

101. Interpretation
All the four lights in the absence of
manifest squint : Normal BSV
Patient sees four lights even in the
presence of a manifest squint: Abnormal
retinal correspondence (ARC)
Only two red lights: left suppression
Only three green lights:right suppression.
Three green lights and two red lights,
alternately: Alternating suppression
Five lights (2 red and 3 green): Diplopia

102. Evaluation of sensory status
Bagolini striated glasses test
This is a test for detecting BSV, ARC or suppression.
Each lens of Bagolini Glasses have fine parallel
striations which convert point source of light into a
line
Procedure
a) 2 lenses placed at 45 and 135 degrees in front of
each eye respectively
b) Patient asked to fixate a small light source. Testing
distance at 6m and 33 cm
c) Each eye perceives an oblique line of light
perpendicular to the lens striation

103. Interpretation
If 2 streaks intersect at their centres in form
of oblique cross : BSV or ARC of
harmonious type
If only one streak is seen : There is no
simultaneous perception and suppression
is present.
Small gap in one of the streak: Central
suppression
If the two lines are seen but they do not
form a cross: Diplopia

104. Evaluation of sensory status
Synoptophore
Synoptophore is used for many diagnostic and
therapeutic indications
1. Synoptophore tests for sensory functions
include:
a) Estimation of grades of binocular vision
b) Detection of normal/abnormal retinal
correspondence(ARC).
c) It is done by determining the subjective and
objective angles of the squint
d) A map of suppression scotoma
2. As a part of orthoptic treatment

105. Tests for stereopsis
Titmus
• Red-green spectacles
TNO random dot test
• Hidden’ shapes seen
• Polaroid spectacles
• Figures seen in 3-D
Lang
• No spectacles
Frisby
• ‘Hidden’ circle seen
• No spectacles
• Shapes seen

106. Measurement of deviation
Prism Cover Test
Alternate Cover test
Cover and Uncover test
Krimsky Test
Hirschberg test
Cover test
Maddox Rod Test
Maddox Wing Test

107. Hirschberg Test

108. Cover test

109. Cover and Uncover test

110. Alternate Cover test
Used to diagnose
• Small degree of tropia
and phoria
• Detecting amblyopia
• Comparing primary
and secondary deviation

111. Prism Cover Test

112. Krimsky Test

113. Maddox Rod Test
Consists of multiple cylindrical high plus
lenses of red colour set together in a
metallic disc which converts appearance of
white spot of light into a red streak
Measures horizontal and vertical deviations
PROCEDURE:
1.Patient asked to fix on a point of light in
centre of Maddox tangent scale at distance
of 6m
2.Maddox rod is placed in front of 1 eye

114. Maddox rod converts point light image
into a line
•Patient sees a point light with 1 eye and
a red line with other
• Due to dissimilar images of 2 eyes,
fusion is broken and heterophoria
becomes manifest
The number on Maddox tangent scale
where red line falls will be amount of
heterophoria in degrees

115. Maddox Wing Test
Based on principle of dissociation by dissimilar
objects
• Measures heterophoria for near (33 cm)
•Through 2 slits:
RE sees vertical white arrow and horizontal red
arrow
LE sees vertical and horizontal line of numbers

116. PROCEDURE:
Patient asked to tell number on horizontal
line onto which vertical arrow is
pointing(gives amount of Horizontal phoria)
•Similarly, number on vertical line at which
red arrow is pointing (vertical phoria
measurement)

117. Head Posture
Examination of Motor Status
(i) Vertical (chin elevation or depression)
(ii) Horizontal (face turn to R or L)
(iii) Torsional (head tilt to R shoulder or
L shoulder
Important sign for Incomittant Squint

118. Ocular motility
Examination of Motor Status
Uniocular motility Binocular motility

119. • Accomodation and convergence should go hand in hand.
• At times convergence is defective
• Convergence insufficiency
Convergence Test

120. Evaluation of Diplopia
1. Diplopia charting
Patient tells about the position and separation of two images in different fields.
2. Hess and Less Screen Test
Plot the dissociated ocular position as a function of extraocular muscle action.
Help for differentiation of paretic strabismus (caused by neurological pathology)
from restrictive myopathy.
They also allow quantitative monitoring of progress in a range of conditions.

121. Diplopia Chart Hess Screen Chart

122. 3. Forced duction test (FDT)
It is performed to differentiate between the paralytic squint and that due to
mechanical restriction of the ocular movements.
FDT is positive (resistance encountered during passive rotation) in cases of
Incomitant squint due to mechanical restriction
Negative in cases of extraocular muscle palsy.
4. Forced Generation test
Differentiate palsy vs paresis in restrictive myopathy

123. MANAGEMENT

124. Goals of treatment and management
• Obtaining normal visual acuity in each eye
• Obtaining and/or improving fusion
• Eliminating any associate sensory adaptations
• Obtaining a favorable functional appearance of
the alignment of the eye.

125. Heterophoria
• Indicated in : decompensated heterophoria
• Correction of refractive error
• Orthoptic treatment: simple, using prism ,
synoptophore
• prescription of prism in glasses
• Miotic drugs: atropine 1%
• Surgical treatment: bi-medial recession
bilateral resection

127. Heterotropia
Concomitant squint
• Spectacle with full correction of refractive error.
• Added lens power
• Occlusion therapy
• Orthoptic exercises: aim: improve fusional range
binocular single vision
exercises: simple , using prism and synoptophore.

128. • Squint surgery:
• AIM:
• Indication:
• Basic principles:
1. Shifting the insertion posteriorly: recession,marginal myotomy
, myectomy
2. Shortening the muscle :resection,tucking and advancement.
• Complications:

129. Incomitant squint
paralyticsquint
• Treatment of the cause
• Conservative measures
• Treatment of diplopia
• Chemo denervation: botulinum type A toxin
• Surgical treatment
A’ and‘V’patternheterotropia
• Surgical treatment:
 weakening of overacting oblique muscles.
 Transpositioning of horizontal rectus muscles

130. Summary

131. Anatomy
• Extraocular muscles
- 6 in number:
• Lateral Rectus by VIth CN (Abducent)
• Superior Oblique by IVth CN (Trochlear)
• Medial Rectus
Inferior Oblique All 4 by IIIrd CN (Oculomotor)
Inferior Rectus
Superior Rectus

132. 1. Herring’s Law of equal innervation
- an equal and simultaneous innervation flows from the
brain to a pair of muscles that contract simultaneously during
binocular movements
2. Sherrington’s law of reciprocal innervation
- during ocular motility increased flow of innervation to the
contracting muscle is accompanied by decreased flow of
innervation to relaxing antagonistic muscle
Laws Governing Ocular Movements

133. Physiology
• Saccadic system
• Smooth pursuit system
• Vergence system
• Vestibular system
• Optokinetic system
• Position maintenance system
Supranuclear Eye Movement Systems

134. • Binocular single vision: When a normal individual fixes his
visual attention on an object of regard , the image is
formed on the fovea of both the eyes separately; but he
individual perceives a single image
• GRADES OF BINOCULAR SINGLE VISION:
Grade 1- simultaneous perception
Grade 2- fusion
Grade 3- stereopsis
• ANOMALIES OF BINOCULAR VISION:
1. Suppression
2. Amblyopia
3. Abnormal retinal correspondence
4. Diplopia

135. Strabismus
• Misalignment of visual axis of two eyes
• Types: Apparent Squint
Latent Squint
Manifest Squint
- comitant
- incomitant

136. Apparent/ Pseudostrabismus
• In apparent strabismus, the visual axes are in
fact parallel, but the eyes seem to have a squint.
• Its is of two types:
1. Pseudoesotropia or apparent convergent
squint.
2. Pseudoexotropia or apparent divergent squint.

137. Latent squint/heterophoria
• Condition in which the tendency of the eyes to
deviate is kept latent by fusion. Therefore, when
the influence of fusion is removed the visual axis
of one eye deviates.
• Types: Esophoria
Exophoria
Hyperphoria
Hypophoria
Cyclophoria

138. Comitant Squint
• Type of manifest squint in which the amount of deviation
in the squinting eye remains constant but there is no
associated limitation of ocular movement
• Due to sensory/motor/central obstacles during
development phase of binocular vision (3-6 months up to
5-6 years)
• Types: Convergent (esotropia)
Divergent (exotropia)
Vertical (hyper/hypotropia)

139. Incomitant squint
Type of Manifest Squint in which amount of
deviation varies in different gaze directions
• Paralytic Squint - ocular deviation to complete or incomplete paralysis
of one or more extraocular muscles eg: trauma, myasthenia graves,
myopathies
• A-V Pattern Heterotropia - Amount of deviation in squinting eyes
varies - > 10 and 15 degrees, respectively, in upward and downward
gaze
eg: dysfunction of oblique muscles
• Restrictive Squint - movement of extraocular muscles is restricted
eg: Orbital blowout fracture

140. Evaluation
History
Evaluation of Motor Status
Test for Diplopia
Test for stereopsis
Evaluation of sensory status
Visual Acuity
Measurement of deviation

141. Available treatment options
• Treatment is indicated in decompensated
heterophoria
• Correction of refractive errors
• Orthoptic treatment
• Prescription of prism in glasses
• Surgical treatment - bimedial recession or
bilateral resection
Heterophoria

142. Heterotropia
• Spectacle with full correction of refractive error.
• Occlusion therapy
• Preoperative orthoptic exercises
• Squint surgery
Comitant Squint

143. Incomitant squint
• Treatment of the cause
• Conservative measures
• Treatment of diplopia
• Chemodenervation
• Surgical treatment
Surgical treatment:
➢weakening of overacting oblique muscles.
➢ transpositioning of horizontal rectus
muscles
Paralytic Squint
A&V Patterns of heterotropia

144. THANK YOU