1. Extra Ocular Movements
(aka)
…and you thought hyperopia was bad…

2. WHAT ARE WE GOING TO DO T’DAY?
Some (very, very little) Basics
Extra Ocular Muscles
Innervation
Control of movements
Movements
Terminology
Actions
Testing

3. BASICS

4. The Extra Ocular Muscles

5. The Extra Ocular Muscles -Origin

6. The Extra Ocular Muscles -Origin
TROCHLEA SR SO
Annulus LR MR IR IO

7. The Extra Ocular Muscles -Origin
TROCHLEA SR SO MR LR IR IO

8. The Extra Ocular Muscles -OriginSR SO LR IO IR

9. The Extra Ocular Muscles -OriginSR
TROCHLEA SO MR IO IR

10. The Extra Ocular MusclesSR SO MR LR IR IO

11. The Extra Ocular MusclesIO SO MR LR SR

12. The Extra Ocular MusclesSR SO LR MR IO IR

13. The Extra Ocular MusclesMR SR LR

14. The Extra Ocular MusclesSO IO
51°
23° SR IR
OPTICAL AXIS

15. THE EXTRA OCULAR MUSCLES
Superior & Inferior Recti make an angle of 23° with the eye ball
Superior & Inferior Obliques make an angle of 51° with the eye ball
Angular attachment allows for actions in multiple directions

16. INNVERVATION
LR6 SO4 O3

17. SOME RULES

18. RULES #1 BOTH EYES MUST MOVE TOGETHER
MUSCLES IN BOTH EYES ARE THUS PAIRED
PARIED MUSCLES (YOKE MUSCLES) HELP MOVE THE EYE IN A GIVEN DIRECTION.
THEY BOTH THUS GET SIMILAR STIMULATORY SIGNALS FROM THE BRAIN (HERRINGS LAW)

19. RULES #2 MUSCLES IN ONE EYE HAVE AN AGONIST- ANTAGONIST RELATIONSHIP
THE HORIZONTAL RECTII FORM ONE SET
THE VERTICAL RECTII/ OBLIQUES FOR THE OTHER SET
WHEN ONE MUSCLE IN THE SET CONTRACT THE OTHER MUST RELAX (SHERRINGTON’S LAW)

20. RULES #3
MUSCLE ACTIONS & TESTING ARE DIFFERENT!

21. CONTROL OF MOVEMENTS

22. WHY? Eyes; you have to see
Eyes must ‘fix’ on an object for you to see clearly
Two Step process
Find what you want to see (Voluntary fixation)
Keep your eyes ‘glued’ to it (Involuntary fixation)

23. STEP 1: Find what you want to see
STEP 2: Keep your eyes fixed on it

24. SUPRA NUCLEAR: CONTROL MEHANISM

25. CONTROL MECHANISMS INVOLUNTARY VOLUNTARY
Tremors (Help keep image refreshed)
Drifts (Help keep image refreshed)
Flicks (Help eyes move so that image fall on fovea again)
VOLUNTARY
Pursuits (Slow movements to ‘track’ objects)
Saccades (Fast movements to ‘jump’ to objects)

26. INVOLUNTARY MOVEMENTS
DASHED = TREMORS/ DRIFTS
SOLID = FLICKS

27. VOLUNTARY MOVEMENTS PURSUITS SACCADES To ‘follow’ objects
What we usually test
SACCADES
To ‘rapidly’ shift gaze to an object of interest

28. THE SUPERIOR COLLICULI
Jack of all trades
Help in involuntary tracking
Help in voluntary tracking
Even if the visual cortex is kaput, these help turn the head in direction of ‘interest’

29. NUCLEAR LEVEL CONTROL Co-ordinate eye movements -Between eyes*
-Eyes and ears
-Eyes and neck
Mostly via Superior colliculus*

30. VOLUNTARY MOVEMENTS Pursuits Saccades

31. EXTRAOCULAR MOVEMENTS
ROTATIONAL MOVEMENTS X Y Z

32. PURSUITS (also applies to saccades, but we’ll deal with those a little later)

33. TERMINOLOGY DUCTIONS VERSIONS VERGENCE Examining movement of one eye
Remember it is not possible to move one eye alone!
VERSIONS
Movements of both eyes in the same direction
VERGENCE
Movements of both eyes in opposite direction

34. PURSUITS: DUCTIONS

35. TERMINOLOGY: DUCTIONS

36. Rotation around ‘Y” axis
TORSIONAL MOVEMENTS
INTORSION
Inward rotation
Superior Rectus & Oblique
EXTORSION
Outward rotation
Inferior Rectus & Oblique
Rotation around ‘Y” axis
HELP KEEP YOUR WORLD STRAIGHT!

38. PRACTICE!

39. PURSUITS: VERSIONS

40. TERMINOLOGY: VERSIONS
HERING’S LAW
SUPRA VERSION
One eye follows the other
Agonist Pairs in both eyes
DEXTRO VERSION
LEVO VERSION
These are called ‘Yoke’ muscles
Both get equal impulses
INFRA VERSION

41. TERMINOLOGY: VERSIONS
SHERRINGTON’S LAW
SUPRA VERSION
The antagonist muscles to yokes…
… are inhibited…
DEXTRO VERSION
LEVO VERSION
…to allow for optimal actions…
…of yoke muscles
INFRA VERSION

42. TORSIONAL MOVEMENTS
TORSIONAL MOVEMENTS CAN ALSO BE DEFINED FOR BOTH EYES
INWARD ROTAION: INCYCLOVERSION
OUTWAR ROTATION: EXCYCLOVERSION

43. PURSUITS: VERGENCE

44. TERMINOLOGY: VERGENCE

45. THE NUT CRACKER Its all good knowing Versions & Ductions
But they DO NOT tell us anything about integrity of muscle function
As clinicians it is more important to know about muscle functions

47. MUSCLE ACTIONS ACTIONS ARE DETERMINED BY POSITION OF EYE BALL
Primary Position: Straight ahead
Secondary Positions: Left, Right, Up, Down
Tertiary positions: Oblique
MUSCLES, THUS, HAVE COMPLEX ACTIONS

48. MUSCLE ACTIONS
EYES STRAIGHT
EYES U/D/L/R
EYES OBLIQUE

49. MUSCLE ACTIONS
MUSCLES, THUS, HAVE COMPLEX ACTIONS 

50. MUSCLE ACTIONS
THANK FULLY WE OPHTHALMOLOGISTS ARE MASTERS OF SIMPLFICATIONS
 → 

51. MUSCLE TESTING We want to know: Is the muscle Working?

52. MUSCLE TESTING An amazing over-simplification Makes life easy
One muscle = Moves eye in one position only
Six muscles = Six position = Cardinal positions

53. MUSCLE TESTING: CARDINAL POSITIONS

54. DEXTRO-CYCLO Whaa….?? To make things even simpler
Refer to eye positions with reference to where they are in relation to the straight gaze

55. MUSCLE TESTING: CARDINAL POSITIONS
UP & IN
UP & OUT
OUT IN
DOWN & OUT
DOWN & IN

56. THESE ARE YOKE PAIRS (ACTING IN PAIRS)
EYE MOVEMENTS
THESE ARE YOKE PAIRS (ACTING IN PAIRS)
RT: SR LT: IO
RT: IO LT: SR
UP RT
UP LT
RT: MR LT: LR
RT: LR LT: MR LT RT
RT: IR LT: SO
RT: SO LT: IR
UP RT
DWN LT

57. THE RECTUS- OBLIQUE INTRIGUE
Superior & Inferior Rectii elevate and depress an abducted eye respectively
Inferior & Superior Oblique elevate and depress an adducted eye respectively

58. THE RECTUS- OBLIQUE INTRIGUE
To Remember this:
Minimize Angle between:
Eyeball & muscle
The position of the eye ball
Determines muscle action

59. THE RECTUS- OBLIQUE INTRIGUE
1: RECTII MUSCLES
1. Minimize Angle
23°
2. EYE ABDUCTS
3. RECTII THEN ELEVATE OR DEPRESS

60. THE RECTUS- OBLIQUE INTRIGUE
2: OBLIQUE MUSCLES
51°
1. Minimize Angle
2. EYE ADDUCTS
3. OBLIQUES THEN ELEVATE OR DEPRESS

61. THE RECTUS- OBLIQUE INTRIGUE
Superior & Inferior Rectii elevate and depress an abducted eye respectively
Inferior & Superior Oblique elevate and depress an adducted eye respectively
The eye DOES NOT have to be turned exactly 23° or 51°. Maximal abducted or adducted gaze would do

62. EYE MOVEMENTS RT: SR LT: IO RT: IO LT: SR RT: MR LT: LR RT: LR LT: MR
UP RT
UP LT
RT: SR LT: IO
RT: IO LT: SR RT LT
RT: LR LT: MR
RT: MR LT: LR
UP RT
DWN LT
RT: SO LT: IR
RT: IR LT: SO

65. MUSCLE TESTING Wait… What about up & down gaze
As well as Straight ahead??
These movements involve more than one muscle
Cardinal Positions +
Straight ahead (all muscles)
Up (Superior Rectus + Inferior Oblique)
Down (Inferior Rectus + Superior Oblique)
= 9 Diagnostic Positions of gaze

66. 9 DIAGNOSTIC POSITIONS OF GAZE
RT: SR LT: IO
SR + IO (BE)
RT: IO LT: SR
RT: LR LT:MR
RT: MR LT: LR
ALL MUSCLES
RT: SO LT: IR
RT: IR LT: SO
IR + SO (BE)
SIX CARDINAL POSITIONS
+ STRAIGHT
+ UP
+ DOWN
= 9 DIAGNOSTIC POSITIONS

67. CLINICAL SKILL RT: SR LT: IO SR + IO (BE) RT: IO LT: SR RT: LR LT:MR
MAKE A BROAD 3 LIMBED “H”, OBSERVING THE EYE AS IT MOVES
RT: SR LT: IO
SR + IO (BE)
RT: IO LT: SR
RT: LR LT:MR
RT: MR LT: LR
RT: IR LT: SO
IR + SO (BE)
RT: SO LT:IR
LIMB 1
LIMB 2
(Not very useful as can’t isolate one muscle dysfunction)
LIMB 3

68. CLINICAL SKILL
IT does not matter how the triple limb “H” is formed as long as all directions are tested!

69. EOM SKILL: PURSUITS IN PAIRS

70. SACCADES

71. SACCADES
All of what we have done
Only faster!

72. EOM SKILL: SACCADES IN PAIRS

73. UTILZING SACCADES & PURSUITS
Continuously follow a moving object with eyes
Like the pen in the video above
A ball rolling along the ground
A pretty figure walking by
Watching videos
SACCADES
Switch gaze to a point of interest rapidly, really rapidly.
Like the pen and hand in the video above
A cricket ball being bowled or hit
Objects that pass by you as you drive
Reading (changing lines)
Observing paintings

74. WHAT HAPPENS WHEN A MUSCLE FAILS TO FUNCTION?

75. EOM PALSY The eye fails to move in the direction of muscle function
The visual axis are misaligned (‘PARALYTIC-SQUINT’)
Eye turned in (adducted) = Internal squint (ESO-TROPIA)
Eye turned out (abducted) = External squint (EXO-TROPIA)

76. EOM PALSY The patient experiences diplopia
If the patient in an adult the diplopia is intractable (i.e. will not go away)
Patients adopt a compensatory head posture to get over the diplopia
To minimize misalignment of axis
OR they simply close their eye
If the patient is a child (< 9 years) the visual cortex will ‘adapt’ by suppressing the blurrier of the two images to negate diplopia OR
They adopt a compensatory head posture to get over the diplopia

77. INTERNAL SQUINT
MINIMIZE MIS-ALIGMENT OF EYES
TURN HEAD SO THAT THE RIGHT EYE MOVES OUT

78. JUST LIKE LOOKING TO THE RIGHT
VISUAL AXIS ARE ‘RE-ALIGNED’

79. OTHER WAYS OF GETTING A SQUINT
FAULT IN EITHER OF THESE MECHANISMS
CAN CAUSE CHILDHOOD SQUINT
EYE MOVEMENTS NORMAL
CALLED ‘NON-PARALYTIC SQUINTS’