different squint patterns

1. Pattern Deviations
Horizontal deviation
Difference in the magnitude of deviation
between
up
gaze and downgaze

2. • V pattern
• A horizontal deviation that is more divergent (less convergent) in upgaze than in
downgaze
• A pattern
• A horizontal deviation that is more divergent (less convergent) in downgaze than in
upgaze
• An A or V pattern is found in 15%–25% of horizontal strabismus cases.
• Less common variations of pattern strabismus
• Y, X, and λ(lambda) patterns

3. Oblique Muscle and Orbital Pully system
• Muscle
• Tertiary abducting action of
• IO in UP Gaze
• SO In downgaze
• To some extent ocular
torsion
• Pully system: oblique
muscle overactions
• Altered rectus muscle
pathways and functions
• Patients with upward- or
downward- slanting palpebral
fissures
• May show A or V patterns
• Because of an under lying
variation in orbital
configuration,
• Reflected in the orientation of
the fissures

4. • Directions the eye is pulled by the actions of a muscle (from the primary position) do not
correspond to the diagnostic position of gaze in which the eye is placed to test the strength
of that muscle
• Diagnostic positions of gaze, also called the cardinal positions of gaze, are determined by
aligning the muscle and the optical axis
With the exception of the horizontal rectus muscles
Pascal Benzene Ring
Diagnostic gaze directions

5. • When the eye is adducted 67 degrees
• Vertical recti are pure torters
• When the eye is abducted 39 degrees
• Obliques are pure torters
In intermediate locations the vertical movers also act as addctors and abductors

6. Ocular torsion
• Not as consequential as pulley dystopia
• Torsion displaces the anterior path of the vertical rectus
muscle
• Extorsion
• Displaces the superior rectus muscle temporally
• Inferior rectus muscle nasally
• Tends to produce a V pattern
• Intorsion
• Displaces the superior rectus nasally
• Inferior rectus temporally,
• Tends to produce an A pattern

7. Rare patterns
• X pattern
• Restricted horizontal rectus
muscles
• Contracture of the lateral rectus
muscles in large- angle
exotropia may result in an with
globe slippage in adduction
• Y pattern
• Anomalous innervation
• Sometimes seen in isolation
• sometimes associated with
other congenital cranial
dysinnervation disorders
• λ Pattern
• variant of A- pattern exotropia
• The horizontal deviation is the
same in primary position and
upgaze but increases in
downgaze

8. V Pattern deviations: Approach to Dx
• History
• Clinical features
• Testing
• Evaluation
• Etiology & Epidemiology

9. History
• Head Posture
• Chin up
• Exo V pattern
• Chin down
• Eso V Pattern
• H/O surgery
• Head trauma

10. Clinical features
• Horizontal deviation more convergent in down gaze than
up gaze
• Cliinically significant
• > 15 PD between up gaze and down gaze
• Measured 25 degrees from primary position
• Fixing on an accommodative target at distance with refractive
correction

11. Testing & Evaluation
• Cover test
• Prism and alternate
• In up and down gaze
• Assess ductions and versions
• CT or MRI of orbit;
• coronal view if orbital anatomical abnormality suspected
• Neuroimaging is must in case of sup oblique palsy

12. Etiology: Unknown
• ? Primary or secondary
muscle dysfunction
• IOOA
• SOUA
• Horizontal muscle dysfunction
• Increased lateral rectus action in
up gaze
• Increased med rectus action in
down gaze
• Vertical muscle dysfunction
• Tertiary action in adduction
• Cranio facial malformations
• Apert
• Crouzon

13. Epidemiology & Risk factors
• Pattern deviations in 25 % of all
squint cases
• V Pattern most common;
especially in esotropia
• Risk factors
• Infantile esotropia
• H/O Sx
• Apert; crouzon
• SO palsy ( Especially bilateral)
• Brown syndrome
• Divergence on attempted elevation
from primary position

14. IOOA/Overelevation In adduction
• Primary IOOA; No
Associated with SO palsy
• Usually in infantile
esotropia
• Abnormal head
posture/Head tilt
• Abnormal movement of eye
in extreme gaze
• Misalignment of eye in side
gaze
• Secondary
• SO palsy/paresis
• Or yoke muscle SR
• Or restriction of
contralateral IR

15. Clinical features: V pattern
• Over elevation in adduction
• Abducted eye depressed with hypotropia
on alt cover test
• Positive head tilt test in SO palsy
• Excyclotorsion on Fundus exam
• Look for IOOA in
• Infantile esotropia
• Latent nystagmus
• DVD
• Head tilt
• IV N palsy

16. IOOA: DD
• Restrictive orbitopathy
• DVD
• Duane with upshot
• Post op complication
• IO transposition

17. Management
Surgery
• Recession
• Myectomy
• Transposition/Anteririsation
• Denervation/extirpation
Complications
• Consecutive/residual vertical
squint: A pattern
• Persistant IOOA
• Unmasking of contralateral
IOOA
• Ocular torsion

18. Management: Surgery
• Weakening of IO
• If IOOA
• Weakening corrects upto 15 – 20
PD
• Self adjusting; Over correction
rare
• Ant transposition if DVD is
present or may occur post surgery
• Horizontal Muscle displacement
• If no or little oblique dysfunction
• ½ of tendon width
• MALE
• MR to apex LR to empty spsce
• Med rectus downward and lat retus
up ward displacement

19. Surgery
• SO tuck
• If SOunderaction
• Unpredictable
• Brown may result
• Horizontal displacement of vertical
• Rare option

20. DVD
• Infantile esotropia
• May occur later in life
• Latent nystagmus
• Compensatory head tilt
• One or both eyes drifting
upwards spontaneously
• ? Outward’ excyclotortsion
• Bilateral!!
• Asymeric
• Compensatory head tilt

21. Management
• Faden
• SR recession
• IO transposition
• IR resection

22. A Pattern
• SOOA
• IOUA
• Horizontal muscle dysfunction
• Increased MR action in upgaze
• Increased LR in downgaze
• Anomalous Head posture
• Chin up A eso
• Chin down A exo
• IOOA
• SOUA
• Horizontal muscle dysfunction
• Increased lateral rectus action in up gaze
• Increased med rectus action in down gaze
• Head Posture
• Chin up
• Exo V pattern
• Chin down
• Eso V Pattern

23. Clinical features
• Horizontal deviation
• More convergent in up gaze compared to downgaze
• > 10 PD difference between up and down gaze: :Significant
• 25 degrees from primary position. fixing distance object
• Refractive correction to control accommodation

24. Risk factors
• Prior Sx
• Primary SOOA
• IO palsy
• Craniosynostosis
• Trisomy 21

25. Management
• Appropriate refraction and amblyopia management
• Surgery
• SO tendon weakening
• Tenotomy; recession; spacer
• If significant OA
• Complications: Torsional imbalance
• large esotropic shift in down gaze & no eso shift in primary gaze;

26. Surgery
• Horizontal muscle displacement
• If little or no oblique dysfunction
• ½ tendon width
• MR displaced upward & LR downward
• MALE

27. SO tendon sheath Syndrome: Brown
• Congenital/Acquired
• Constant/Intermittent
• May resolve spontaneously
• 10% bilateral
• Chin up, face turn to
opposite side
• ? ? Diplopia
• ! ! Audible click

28. • Deficient elevation in adduction and improves with
abduction
• Attempted elevation in midline: V pattern
• Adduction cause widening of palpebral fissure
• Downshoot of involved eye
• Hypotropia in primary position