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Extraocular Motility

Extraocular Motility

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Extraocular Motility

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  1. Extraocular Motility Walter Huang, OD Yuanpei University Department of Optometry

  2. Extraocular Muscles • Purpose • To control the movement of the globe

  3. Extraocular Muscles • Rectus muscles • Superior rectus muscle (SR) • Inferior rectus muscle (IR) • Medial rectus muscle (MR) • Lateral rectus muscle (LR) • Oblique muscles • Superior oblique muscle (SO) • Inferior oblique muscle (IO)

  4. Anterior View of Right Eye

  5. Superior View of Right Orbit • Action of muscles affected by globe position in the ocular orbit and muscle orientations

  6. Posterior View of Right Eye

  7. Medial Rectus • Along the medial aspect of the eyeball, the medial rectus muscle inserts at a point 5.5mm of the limbus • It is controlled by the oculomotor nerve (cranial nerve III) • Contraction of this muscle causes adduction of the eye

  8. Medial Rectus Adduction

  9. Lateral Rectus • Along the lateral aspect of the eyeball, the lateral rectus muscle inserts at a point 7.0mm of the limbus • It is controlled by the abducens nerve (cranial nerve VI) • Contraction of this muscle causes abduction of the eye

  10. Lateral Rectus Abduction

  11. Inferior Rectus • Along the inferior aspect of the eyeball, the inferior rectus muscle inserts at a point 6.5mm of the limbus • It is controlled by the oculomotor nerve (cranial nerve III)

  12. Inferior Rectus When the eyeball is positioned 23 degrees outward in the orbit with respect to primary gaze, contraction of this muscle causes depression of the eye When the eyeball is positioned 67 degrees inward in the orbit with respect to primary gaze, contraction of this muscle causes excycloduction of the eye

  13. Inferior Rectus When the eyeball is positioned straight ahead in the orbit with respect to primary gaze, contraction of this muscle causes adduction of the eye Contraction of this muscle causes depression, excycloduction, and adduction of the eye

  14. Position of IR and SR

  15. Primary Action of IR • Depression

  16. Secondary Action of IR • Excycloduction

  17. Tertiary Action of IR • Adduction

  18. Superior Rectus • Along the superior aspect of the eyeball, the superior rectus muscle inserts at a point 7.5mm of the limbus • It is controlled by the oculomotor nerve (cranial nerve III)

  19. Superior Rectus When the eyeball is positioned 23 degrees outward in the orbit with respect to primary gaze, contraction of this muscle causes elevation of the eye When the eyeball is positioned 67 degrees inward in the orbit with respect to primary gaze, contraction of this muscle causes incycloduction of the eye

  20. Superior Rectus When the eyeball is positioned straight ahead in the orbit with respect to the primary gaze, contraction of this muscle causes adduction of the eye Contraction of this muscle causes elevation, incycloduction, and adduction of the eye

  21. Primary Action of SR • Elevation

  22. Secondary Action of SR • Incycloduction

  23. Tertiary Action of SR • Adduction

  24. Superior Oblique • The superior oblique muscle passes through the trochlea and its insertion on the eyeball below the superior rectus muscle is at 51 degrees with respect to primary gaze • It is controlled by the trochlear nerve (cranial nerve IV)

  25. Superior Oblique When the eyeball is positioned 39 degrees outward in the orbit with respect to primary gaze, contraction of this muscle causes incycloduction of the eye When the eyeball is positioned 51 degrees inward in the orbit with respect to primary gaze, contraction of this muscle causes depression of the eye

  26. Superior Oblique When the eyeball is positioned straight ahead in the orbit with respect to the primary gaze, contraction of this muscle causes abduction Contraction of this muscle causes incycloduction, depression, and abduction of the eye

  27. Position of SO and IO

  28. Primary Action of SO • Incycloduction

  29. Secondary Action of SO • Depression

  30. Tertiary Action of SO • Abduction

  31. Inferior Oblique • The insertion of the inferior oblique muscle is on the eyeball below the lateral rectus muscle at 51 degrees with respect to primary gaze • It is controlled by the oculomotor nerve (cranial nerve III)

  32. Inferior Oblique When the eyeball is positioned 39 degrees outward in the orbit with respect to primary gaze, contraction of this muscle causes excycloduction of the eye When the eyeball is positioned 51 degrees inward in the orbit with respect to primary gaze, contraction of this muscle causes elevation of the eye

  33. Inferior Oblique When the eyeball is positioned straight ahead in the orbit with respect to the primary gaze, contraction of this muscle causes abduction Contraction of this muscle causes excycloduction, elevation, and abduction of the eye

  34. Primary Action of IO • Excycloduction

  35. Secondary Action of IO • Elevation

  36. Tertiary Action of IO • Abduction

  37. Functions of Extraocular Muscles

  38. Functions of Extraocular Muscles

  39. Terminology • Duction: describes movement of one eye • Abduction • Adduction • Supraduction or elevation • Infraduction or depression • Incycloduction or intorsion • Excycloduction or extorsion

  40. Terminology • Version: describes movement of two eyes in the same direction • Dextroversion • Levoversion • Supraversion • Infraversion

  41. Terminology • Vergence: describes movement of two eyes in opposite directions • Convergence • Divergence

  42. Version and Vergence

  43. Near Point of Convergence • Maximum convergence ability or NPC is measured by as part of confrontational testing • NPC = point of intersection of line of sight when eyes are maximally converged • Theoretically, NPC should be measured from center of rotation of eyes • Clinically, NPC is measured from the facial plane

  44. Near Point of Convergence • NPC break point (target becomes double) greater than 7cm is considered abnormal • Average NPC is approximately 5cm • The recovery point (target becomes single) is expected to be within 10cm

  45. Near Point of Convergence • A patient with reduced NPC • Convergence insufficiency • Some presbyopes • Symptoms • Diplopia, frontal headache, asthenopia, fatigue, and reduced reading ability • The patient may benefit from vision therapy or prism in reading Rx

  46. Object Tracking Movements • Saccade: fast, step-like eye movement (up to 1000 deg/sec) that places image of the target on the fovea • Reading • Looking from point A to B • Fixating on a stationary target

  47. Object Tracking Movements • Pursuit: slow, smooth-following movement (up to 30 deg/sec) that maintains image of the target on the fovea • Following a moving target

  48. Extraocular Motility Testing • The most common test for extraocular motility is the broad H test • EOM testing is also part of confrontational testing

  49. Extraocular Motility Testing • Purpose • To investigate the integrity of the extraocular muscles and their nerves • To assess the patient’s ability to perform version eye movements • To determine if strabismus is comitant (i.e., deviation does not change with direction of gaze)

  50. Broad H Test • A pursuit test done binocularly with penlight at a test distance of 30 to 40cm • It tests 9 positions of action, starting with primary position