Strabismus

1. Strabismus The art of harmony

2. Extraocular muscles

3. Remember • All EOMs originate from orbital apex posteriorly except IO which originates anteriorly. • The shortest EOM belly is SO. • The EOM with the longest tendon is SO.

4. Axes • Visual axis. • Orbital axis. • Muscle axis.

10. Ocular positions • Primary position. • Position at rest. • 6 cardinal positions. • 9 diagnostic positions.

12. Field of action

13. SR

14. SO

15. Muscle action • Primary. • Secondary. • Tertiary. • Vertical. • Horizontal. • Torsional.

22. Actions of EOMs

23. Recti………………Adduction. • Obliques………….Abduction. • Superiors…………..Intorsion. • Inferiors…………….Extorsion.

25. Muscle axis in line with visual axis………….full action. • Muscle axis perpendicular to visual axis……….Nil action.

27. Physiology of ocular rotations • Listing’s Law. • Axes of Fick.

30. Sherrington’s Law( Law of reciprocal innervation) • Agonist vs Antagonist: MR × LR SR × IR SO × IO

33. Synergists:

34. Hering’s law of yoke muscles.

37. Remember • Sherrington’s law and Synergists………..Single eye movements. • Hering’s law of yoke muscles………………Binocular eye movements.

38. Normal ocular alignment

39. Orthotropia & Orthophoria

40. Strabismus