PATTERN STRABISMUS COMMONLY CALLED AV PATTERN

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.