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Flashcards in Ocular movements Deck (128):
1

The movement or rotation of one eye around the axes of fick

Duction

2

Binocular, simultaneous and conjugate eye movements or rotation of both eyes.

Version

3

Binocular movement where the visual axis of both eyes are in the same direction to maintain fixation with both eyes (Both eyes move in the same direction, by the same amount)

Conjugate eye movements

4

Twists the eyes in the same direction, clockwise or counterclockwise when the head is tilted to the right or left.

Conjugate torsion

5

a disconjugate eye movement where the eyes rotate in opposite directions. (One eye moves right the other eye moves left)

Vergence

6

both eyes rotate in to maintain binocular fixation

Convergence

7

When you read what type of vergence are you having

Convergence

8

What type of law applies to convergence?

And what muscle is yoked to produce this?

Hering law

Medial rectus

9

Both eyes rotate out

Divergence

10

For divergence what muscle in each eye is yoked?

Lateral rectus

11

Rotation of superior portion of both eyes in (tip of OD goes in and the tip of OS goes in)

Incyclovergence

12

Rotation of superior portion of both eyes out

Excyclovergence

13

T/F: vergences are important for fusion

True

14

The time between the presentation of a stimulus and the start of the movement

Latency

15

Are versions faster or slower than vergences?

Faster

16

Are vergences faster or slower than versions?

Slower

17

these include the cranial nerves responsible for eye movements (3, 4, & 6) and the muscles they innervate (all the rectus and oblique muscles).

Infranuclear controls

18

Higher order sensory and motor system that plans and controls the eye movements.

Supranuclear controls

19

What control involves the neural network in the cerebral cortex, cerebellum and brainstem.

Supranuclear control

20

What control visual motor pathway are versions and vergences controlled by?

Supranuclear controls

21

What are the 5 types of versions?

-saccades
-pursuits
-VOR
-OKN
-OKR

22

Fast conjugate eye movements for refixation (on a new target) / swift movements to place and keep images on the fovea (brings image to the fovea)

Saccades

23

Are saccades voluntary or involuntary?

Voluntary

24

What is the speed of saccades?

400-700 degrees/sec

25

T/F: saccades require a strong force to move the eye rapidly in the globe against the viscosity on the orbit

True

26

What is the latency of a saccade?

120-200ms

27

When are saccades well developed?

1 year of age

28

Name 5 examples of saccadic eye movements?

-Response to commands
-Fast phase during optokinetic or vestibular movements
-REM
-Correcting saccades during fast pursuits
-Microsaccades

29

Are saccades faster than pursuits and vergences?

Yes

30

What is the peak velocity of pursuits?

30-60 degrees/sec

31

Eye following moving target to maintains image on the retina (fovea)

Pursuits

32

Do pursuits have a shorter or longer latency compared to saccades?

What is the latency (#)?

Shorter, so its faster to start

125msec

33

When are smooth pursuits better developed?

Month 3-4

34

Are pursuits voluntary or involuntary optokinetic movements?

Voluntary

35

What do pursuits help match?

Eye velocity to target velocity

36

What lobe controls pursuits?

Ipsilateral parietal lobe
(Ex: right pursuit is driven by right parietal lobe)

37

These movements stabilize a retinal image during brief head movement.

Vestibulo-ocular reflex (VOR)

38

Does VOR require stimuli?

No. You can do it with the eyes closed

39

Seen in the oculocephalic maneuver/doll’s head (moving the patient’s head up and down and side to side while asking them to maintain fixation).

VOR

40

When is the horizontal VOR well developed?

What about vertical?

Horizontal- at birth

Vertical-later

41

Doll head result is conjugate eye movements ___ to the head movement.

Opposite

42

What does vestibular damage cause?

Horizontal nystagmus

43

What are the results of a normal VOR?

Eye movements that are equal and opposite to the head movement

44

Do the patients have to be cooperative during VOR testing?

Nahhhhhh, they can be knocked the hell out

45

When do you not want to test VOR

In trauma patients with possible cervical spine injuries

46

Uses warm and cold water to set up temperature gradients in the semicircular canal causing a convection current in the endolymph then stimulating the hair cells.

Caloric testing

47

When would you do caloric testing?

When dolls head cant be performed

48

For caloric testing, the patients head is angled...

30 degrees so the horizontal semicircular canal is perpendicular to the floor

49

With cold water injected what is the normal response?

Nystagmus with fast phase towards the opposite ear

50

What is the response for warm water injected in the ear?

Fast phase towards the ipsilateral ear

51

Responsible for continuous eye movements after
brief head movements/ maintains image during constant head rotation

Optokinetic reflex

52

When does the optokinetic reflex kick in?

After the VOR response fades because of prolonged head movement (more than 30-60 degrees/sec of movement)

53

Optokinetic reflex holds image of the world steady on the retina during_________

Sustained head movement

54

What is a way you can test OKR?

By slowly rotating the patient in a chair for ~20 secs while looking at the patients eyes

55

What is the normal response to OKR?

slow conjugate eye movement then fast phase
opposite the rotation of the chair.

56

Is OKR voluntary or involuntary?

Involuntary

57

Slow pursuit eye movement followed by a fast corrective saccade because a visual field moves over the retina.

Optokinetic Nystagmus (OKN)

58

A conjugate movement maintaining the image of the moving target on the fovea when the head is still

OKN

59

Does OKN require input from the visual system?

Yes

60

When does OKN develop?

3-5 months of age

61

OKN can be used for what kind of patients?

Malingering and uncooperative patients

62

What does a positive OKN response mean?

The VA is at or better than the size of the stripes (the visual motor pathway is intact)

63

What does a negative response mean?

That its inconclusive

64

How far do you hold the OKN drum? And how do you hold it

Hold it at eye level, ~40-50 cm from patient

65

Do you test the OKN at horizontal, vertical, or both?

Both

66

Is there a standard speed on the drum?

No

67

How long should patients be able to sustain fixation?

10 seconds

68

Who cant fixate for 10 seconds?

-young, anxious, hyperactive and/or inattentive patients

69

Ocular motor disorders can show.....

serious neurological, functional or developmental problems.

70

Why would children with difficulty reading have difficulty with pursuits and saccades

Because the smaller, more fixations, and regressions

71

What is the speed of OKN?

30-60 degrees/sec

72

Is OKN movements voluntary or involuntary?

Involuntary

73

The fast phase moves ____ of the OKN drum rotation

Opposite

74

Why are vergences important?

To ensure bifoveal fusion and eliminate diplopia that could occur because of images falling on retinal points that do not correspond.

75

When do vergences occur?

When the disparity exceeds panums fusion area

76

A zone of disparity, if not exceeded, still allows fusion of disparate points.

Panum's fusion area

77

What are the 4 types of vergences

-tonic
-proximal
-fusional
-accommodative

78

This vergence requires attention and cooperation of the cerebral cortex

Fusional vergence

79

This fusional reflex is elicited because of a disparity or a variation in the images at the retina.

Fusional vergence

80

when an object is moving away or towards you, the retinal images are shifted off the corresponding retinal points – so the eyes move to correct the disparity and get the images back on the corresponding retinal points

Fusional vergence

81

The vergence needed to hold eyes straight when eyes are at rest.

Tonic vergence

82

induced convergence movement due to the awareness of near (bringing the phoropter close to the patient)

Proximal vergence

83

A consistent increment of accommodative convergence happens with each diopter of accommodation giving the AC/A ratio.

Accommodative vergence

84

Abnormally high AC/A can produce___

ET with accommodation

85

Abnormally low AC/A makes it harder to ____

Converge, less esotropic, more exotropic

86

The the muscles do / due to the direction of its pull around the axes

Muscle action

87

Major effect on the position of the eye when the muscle contracts while the head is in primary position.

Primary action

88

The position of the eyes when fixating straight ahead. The eyes and head are both straight.

Primary position

89

Position around the X and Z axes of Fick (straight up, straight down, right gaze and left gaze).

Secondary position

90

T/F: the secondary position is purely vertical or horizontal.

True

91

The Y axis (the oblique muscle positions) as well as
head tilt positions.

Tertiary position

92

The positions where only 1 muscle in each eye is
responsible for movement

Cardinal positions

93

The gaze position (one of the cardinal positions) where the effect of a muscle is best observed. You can isolate and evaluate each muscle

Field of action

94

When the SR is abducted 23 degrees and the visual axis and muscle plane (at orbital axis) coincide it acts as an

Elevator

95

When the SR is adducted 67 degrees and the visual axis is perpendicular to muscle plane, the SR becomes an

Intortor

96

When the IR is abducted 23 degrees and the visual axis and muscle plane (at orbital axis) coincide it acts as an

Depressor

97

When the IR is adducted 67 degrees and the visual axis is perpendicular to muscle plane, the SR becomes an

Extortor

98

What is the best position to evaluate the SO?

when the eye is adducted 51 degrees, the visual axis and the direction of pull/muscle plane coincide)

99

Any weakness of the superior oblique can be seen as a failure to....

depression in adduction

100

What is our RSR field of action?

up to the right (abducted), but the actions of the
SR are elevation, intorsion and adduction!

101

The muscle plane/insertion of the SR and IR are along the_____

orbital axes and the orbital axis is 23 degrees of the visual axis.

102

pair of muscle in the same eye that move the eye in
opposite directions.

Agonist-antagonist

103

Give an example of an agonist-antagonist

The medial rectus is the antagonist to the lateral rectus

104

Muscles in the same eye that move the eye in the same direction.

Synergist muscles

105

Give an example of a synergist muscle

The inferior oblique and the superior rectus (both go up)

106

A pair of muscle, one in each eye, that produce conjugate eye movements (moves the eyes in the same direction).
Ex: RLR---LMR
Ex: RIO---LSR

Yoke muscle

107

Increased innervation (and contraction) to one muscle is accompanied by a reciprocal decreased innervation to its antagonist in the same eye

Sherrington law of reciprocal innervation

108

Increased innervation to the left medial rectus to contract makes the left lateral rectus relax is an example of

Sherrington law of reciprocal innervation

109

RMR has increased innervation while RLR does not is an example of?

Sherrington law of reciprocal innervation

110

In left head tilt, RIO & RIR have innervation to EXTORT while RSO & RSR (to intort) do not. LSO &LSR have innervation to INTORT OS while LIO &LIR do not is an example of

Sherrington law of reciprocal innervation

111

during conjugate eye movements, equal and simultaneous innervations flow to yoked muscles.

Hering law of equal innervation

112

When there is a palsy to a muscle, you will notice that the yoke muscle in the other eye will overact. What is this an example of?

Hering law

113

What is this an example of, RMR has increased innervation and LLR has increased innervation.

Hering law

114

What is this an example of, On left head tilt, RIO &RIR have increased innervation to excyclotort the right eye and LSO &LSR have the same innervation to incyclotort the left eye.

Hering law

115

During vertical and oblique versions, what stabilizes the line of sight and prevent horizontal movements?

Horizontal rectus muscles

116

When the unaffected eye is fixating

Primary deviation

117

When the paretic or restricted eye is fixating.

Secondary deviation

118

Why is a secondary deviation larger than a primary deviation?

Because there is an increased innervation to move the paretic eye to fixation.
increased innervation also goes to the non-fixating eye which causes an excessive action and a larger deviation.

119

What happens during a left lateral rectus palsy if the right eye is fixating?

What type of deviation is this?

the left eye turns in because of the unopposed action of the antagonist (left medial rectus). This is Sherrington law!

This misalignment is a primary deviation.

120

What happens during a left lateral rectus palsy if the left eye is fixating?

What type of deviation is this?

additional innervation flows to the LLR to establish this. But, an equal increased innervation also flows to the RMR because of Hering law producing an excessive adduction of the OD

Secondary deviation

121

What is the best position to see the action of the superior oblique?

Depressed and adducted

122

What is the best position to see the action of the inferior oblique?

Elevation and adduction

123

What is the best position to see the action of the superior rectus?

Elevated and abducted

124

What is the best position to see the action of the inferior rectus?

Depressed and abducted

125

If you told someone to look up and to the right but their OD is still in the primary position what muscle is affected?

Superior rectus is damaged

126

If you told someone to look up and to the left but their OD is still in the primary position what muscle is affected?

Inferior oblique

127

If you told someone to look down and to the right but their OS is still in the primary position what muscle is affected?

Superior oblique

128

If you told someone to look down and to the right but their OD is still in the primary position what muscle is affected?

Inferior rectus