Pattern strabismus occurs when there is a change in the magnitude of horizontal deviation between up and down gaze. The most common types are A pattern (convergence in up gaze) and V pattern (divergence in up gaze). Pattern strabismus can be caused by abnormalities of vertical or horizontal muscle action, anatomical anomalies, disorders of muscle innervation, or anomalous muscle insertions. Evaluation involves measuring the deviation in different gazes using cover-uncover testing and Hess screening. Management may involve adaptation or surgery tailored to the specific pattern, which aims to improve alignment and binocular function.

2. • Pattern strabismus is present when a horizontal deviation
change in magnitude between up gaze and down gaze.

4. • Most common types of pattern strabismus is A and V
pattern so commonly called AV pattern strabismus
• Types of pattern strabismus
1. V pattern 5. Lambda
2. A pattern 6.
3. X pattern
4. Y pattern

5. • Most common type
• Relative divergence on up gaze and relative convergence
on down gaze
• Minimum 15 PD difference b/w up gaze and down gaze
• Slight physiological divergence on up gaze

7. • It occur most frequently in pt with infantile esotropia
• V pattern also may occur in pt with S.O palsy particulary
if they are bilateral
• In pt with craniofacial malformation

8. • Second most common type
• Relative convergence on up gaze and relative divergence
on down gaze
• Minimum of 10 PD difference b/w up gaze and down
gaze

10. • Occur most frequently in pt with exotropia
• More common than V pattern in pt with infantile
strabismus associated with craniofacial malformation ,
Down syndrome and myelomenigocele.

11. • When the deviation in primary position increase in both
up gaze and down gaze ( relative divergence )

12. • Commonly seen in pt with large angle exotropia
• Overaction of all four oblique muscle may produce the
increase of exodeviation seen in up gaze and down gaze
( Jampolsky)
• LR muscle contracture could produce a mechanical leash
effect , resulting in the x pattern

13. • When there is relative divergence on up gaze but no
significant change in angle from primary position to down
gaze

14. • Psuedo overaction of I.O
• But there is no fundus torsion , negative head tilt test , no
S.O underaction
• Its due to abberant innervation of LR in up gaze

15. • There is relative divergence on down gaze but no
significant change from primary position to up gaze
• Variant of A pattern exotropia

16. • There is relative convergence on both up gaze and down
gaze compared with primary position

17. A and V pattern

18. A pattern esotropia
A pattern exotropia
V pattern
V pattern esotropia
V pattern exotropia

19. 1. Abnormalities of vertical or horizontal muscles action.
2. Anatomical anomalies.
3. Disorder of muscle innervation.
4. Anomalous insertion of muscle tendon.
5. Sensory torsion .

20. • The horizontal angle of deviation is changed on up gaze
and down gaze by the secondary abducting and
adducting action of vertically acting muscle.

21. • Underaction of one or more commonly both S.O muscle
either congenital or acquired
Down gaze
decrease abduction by u/a S.O
increase adduction by o/a I.R
Up gaze
increase abduction by o/a I.O
decrease adduction by inhibited S.R

22. * underaction of one or usually both S.R
Down gaze
decrease abd by inhibited S.O
increase add by o/a I.R
Up gaze
increase abd by o/a I.O
decrease add by u/a S.R

23. * underaction of one or more often both I.O
Down gaze
increase abd by o/a S.O
decrease add by inhibited I.R
Up gaze
decrease abd by u/a I.O
increase add by o/a S.R

24. • Underaction of one or both I.R u/a
Down gaze
decrease add by u/a I.R
increase abd by o/a S.O
Up gaze
decrease abd by inhibited I.O
increase add by o/a S.R

25. • According to Urist the MR act more effectively on down
gaze and LR are more effective on up gaze , therefore
underaction and overaction of these muscle can
influence the angle of deviation on up gaze and down
gaze.

26. • V eso ______ o/a of MR
• V exo_______o/a of LR
• A eso _______u/a of LR
• A exo________u/a of MR

27. * In craniosynostosis a shallow orbit result in proptosis and
cyclotropia of both globes. This can alter the relationship
b/w the vertically acting muscle , in particular S.O
underaction from shallow orbit and change in rectus
muscles alignment from torsion giving rise to V pattern

28. • In spina bifidia , incyclorotated orbit may explain common
occurrence of A pattern strabismus.
• Mongoloid fissure favoured production of A pattern eso
and V pattern exo and anti mongoloid fissure vice versa.

29. • Bilateral displacement of LR pulley inferiorly would
weaken their action on down gaze and strengthen on up
gaze, resulting in V pattern strabismus.
• A small unilateral inferiorly displacement of LR pulley
mimic clinical pic of I.O overaction in the contralateral eye
.

30. • Bilateral superior displacement of LR pulley give A
pattern.
• A small unilateral displacement of LR pulley superiorly
mimic clinical pic of S.O overaction in the contralateral
eye .

31. * 5. Muscle innervation disorder.
Duane’s retraction syndrome
*6. Sensory torsion.
Intorsion and extorsion ___ change plane of action of
rectus muscles leads to pattern strabismus

32. Aim
• To detect and measure the pattern
• To determine the reason for pattern if possible
• To asses it significant in the management of strabismus

33. AHP
May adopt to get gid of symptom.
*V eso and A exo _______chin depressed .
* V exo and A eso_______chin elevated .

34. • Cover test
• Ocular movement
• Measurement of deviation with PCT
• Investigation of binocular function
• Hess chart .

37. •Surgical management
Aim of surgery
* to restore or improve BSV
* uncomfortable AHP
* achieve better ocular alignment ( cosmesis)

38. General principle for pattern
strabismus surgery
• Pt with pattern associated apparent o/a of oblique
muscles, weakening of the oblique muscles is performed.
• No apparent o/a of oblique muscles then vertical
transposition of horizontal muscles according to MALE
• Surgery on vertical muscles.

39. • V pattern
*when oblique dysfunction is present then weakening of
I.O and strengthening of S.O muscles.
* without oblique dysfuntion
V pattern eso _____ B/L MR recession and downward
transposition of the tendon.
V pattern exo______B/L LR recession and upward
transposition of tendon.

40. • A pattern
* with oblique dysfunction S.O posterior tenotomy (
weakening procedure).
* without oblique dysfunction.
A eso ____ B/L MR recession and upward transposition of
tendon.
A exo ____ B/L LR recession and downward transposition
of tendon.

41. • Y pattern ___ superior transposition of LR
• X pattern ____ recession of LR alone
• Lambda ______ appropriate S.O weakening

42. • For underaction (u/a)
• Superior ( SR and SO) V pattern
• Inferior ( IR and IO) A pattern
• Olique eso pattern
• Recti exo pattern
• Eg SO palsy
• superior its must be V pattern but oblique so its will be
eso i.e V eso.

43. References :
*M Anson and Helen Davis.
*American academy of pediatric
ophthalmology and strabismus.
*A K Khurana.
* Kanski.