Pattern Strabismus | A.V Pattern

PATTERN STRABISMUS COMMONLY CALLED AV PATTERN

1. Pattern strabismus by Azmat Ali optometrist (PICO)

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

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

4. V pattern 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

5. V pattern 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

6. A pattern 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

7. A pattern 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 .

8. X pattern When the deviation in primary position increase in both up gaze and down gaze ( relative divergence )

9. X pattern 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

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

11. 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

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

13. pattern There is relative convergence on both up gaze and down gaze compared with primary position

14. A and V pattern

15. A pattern A pattern esotropia A pattern exotropia V pattern V pattern esotropia V pattern exotropia

16. Aetiology of A and V pattern Abnormalities of vertical or horizontal muscles action. Anatomical anomalies. Disorder of muscle innervation. Anomalous insertion of muscle tendon. Sensory torsion .

17. 1 .Anomalies of vertical muscle action The horizontal angle of deviation is changed on up gaze and down gaze by the secondary abducting and adducting action of vertically acting muscle.

18. V esotropia 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

19. V exotropia * 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

20. A esotropia * 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

21. A exotropia Underaction of one or both I.R u/a D own 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

22. 2 .Anamalies of horizontal muscle action 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.

23. Cont V eso ______ o/a of MR V exo _______o/a of LR A eso _______u/a of LR A exo ________u/a of MR

24. 3. Anatomical anomalies * 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

25. cont 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.

26. 4. Anomalies of muscle pulley 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 .

27. cont 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 .

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

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

30. Observation of the patient AHP May adopt to get gid of symptom. *V eso and A exo _______chin depressed . * V exo and A eso _______chin elevated .

31. Clinical investigation Cover test Ocular movement Measurement of deviation with PCT Investigation of binocular function Hess chart .

32. Measurement of deviation

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

34. 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.

35. 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.

36. 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.

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

38. How to remember pattern ??? 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 .

39. References : *M A nson and H elen Davis. *American academy of pediatric ophthalmology and strabismus. *A K Khurana . * Kanski .