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Motility Block 9 > Ductions And Versions > Flashcards

Ductions And Versions Flashcards

1
Q

Movement of roatation of one eye around the axes of fick (monocular)

A

Duction

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2
Q

How are ductions evaluated

A

With the other eye closed and having the patient move the eye in all directions of gaze

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3
Q

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

A

Version

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4
Q

A binocular movement where the visual axis of both eyes are in the same direction to maintain fixation with both eyes. Both eyes move int he same direction, by the same amount

A

Conjugate eye movements

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5
Q

Conjugate torsion

A

Twists the eyes inthe same direction. Clockwise or counterclockwise when the head is titled to the right or left

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6
Q

Disconjugate eye movement where the eyes (the visual axis) rotate in opposite directions

A

Vergence

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7
Q

Both eyes rotate in to maintina binocular fixation, reading.

A

Convergence

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8
Q

Both eyes rotate out. Lateral rectus in reach eye is yoked

A

Divergence

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9
Q

Rotation of superior portion of both eyes in

A

Incyclovergence

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10
Q

Rotation of superior portion of both eyes out

A

Excyclovergence

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11
Q

Important for fusion

A

Vergences

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12
Q

Temporal characteristics of versions and vergences

A

Both have similar latenicies (about 120-200ms). This is the time between the presentation of a stimulus and the start of the movement

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13
Q

Speed of versions and vergences

A

Function of the size of the movment

Versions are faster
Vergences are slower

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14
Q

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

A

Infranuclear controls

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15
Q

These are the cranial nuclei. Location of other visual motor pathways are in relation to the cranial nuclei

A

Nuclear controls

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16
Q

This is the higher order sensory and motor system that plans and controls the eye movements. This involves the neural network in the cerebral cortex, cerebellum, and brainstem. These controls are not fully understood

A

Supranuclear controls

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17
Q

What are versions and vergences controlled by

A

Supranuclear pathways

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18
Q

Types of eye movements (supranuclear)

A

Versions and vergences

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19
Q

Types of versions

A 
Saccades 
Pursuits 
VOR
OKN
OKR
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20
Q

Fast conjugate eye movements for refixation (400-700 degrees/sec)

A

Saccades

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21
Q

Purpose of saccades

A

Swift movment to place and keep an image on the fovea and/or to move from one image to another-this occurs when an image is on retinal periphery and the person wants to hold attention

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22
Q

To correct the position error between the target and the fovea

A

Saccades

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23
Q

What do saccades require

A

Strong force to move the eye rapidly in the globe against the viscosity on the orbit (fat, etc)

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24
Q

Saccades latency

A

The time between stimulus and response, is 120-200ms. It has an accelerating and decelerating phase

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25
Q

Saccades in infants

A

Can start in infants, but it is inaccurate, Kelly movment until the target is reached

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26
Q

When are saccades well developed

A

By 1 year of age

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27
Q

Examples of saccadic eye movements

A
  • response to commands
  • fast phase during optokinetic or vestibular movements
  • R.E.M. During sleep
  • correcting saccades during fast pursuits
  • microsaccades
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28
Q

Faster than pursuits and vergences

A

Saccades

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29
Q

Are saccades voluntary or involuntary

A

Voluntary, but there can be reflex saccades with sudden visual, auditory, or peripheral stimuli

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30
Q

Brings image to fovea

A

Saccades

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31
Q

Maintains the fovea conjugately on a slowly moving target. Stimulus is a target moving in the parafovea

A

Pursuits

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32
Q

Latency of pursuits

A

Shorter than saccades- meaning faster to start

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33
Q

Peak velocity of pursuits

A

30-60 degrees/dec

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34
Q

Helps match eye velocity to target velocity

A

Pursuits

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35
Q

Used in involuntary optokinetic movements to track a moving object and then refixate with a compensatory saccade to refixate

A

Pursuits

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36
Q

When are smooth pursuits better developed

A

Are better developed by the 3rd and 4th month of life

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37
Q

Which is quicker to start? Pursuit or saccade

A

Pursuit

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38
Q

Shorter latency, pursuit or saccade

A

Pursuit

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39
Q

Faster velocity, saccade or pursuit

A

Saccade

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40
Q

Involuntary, pursuit or saccade

A

Pursuit

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41
Q

Holds image of slow moving target on fovea

A

Pursuits

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42
Q

If target velocity increases during pursuits

A

Pursuit breaks into a jerky movement since it has a velocity of only 30-60/sec

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43
Q

Latency of pursuits

A

125ms

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44
Q

What are pursuit scontrolled by

A

Ipsilateral parietal lobe

-right pursuit driven by right parietal lobe

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45
Q

These movements stabilize a retinal image during brief head movement

A

Vestibulocochlear-ocular reflex (VOR)

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46
Q

Seen in the oculi cephalic maneuver/dolls head (moving the patients head up and down and side to side while asking them to maintain fixation)

A

Vestibular ocular reflex

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47
Q

Does the VOR require stimuli

A

No. Can occur with the eyes close and even in the dark (since it is a response to head movement)

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48
Q

VOR at birth

A

Horizontal VOR is well developed at birth, while vertical VOR developes later

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49
Q

In VOR, what is moveing?

A

The head, not the target

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50
Q

Holds the image steady during brief head movement

A

VOR

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51
Q

Vergence or versions for VOR

A

Versions

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52
Q

Produces eye movement of equal magnitude to head movement but in opposite direction

A

VOR

53
Q

What doe doll head result in

A

Conjugate eye movement opposite to the head movement

54
Q

What causes horizontal nystagmus

A

Vestibular damage

55
Q

Dolls head maneuver or oculocephalic maneuver

A

Patient fixates on an image while the examiner quickly rotates the head in the horizontal plane and then in the vertical plane

56
Q

Normal VOR in dolls head

A

Results in eye movements that are equal and opposite to the head movement

57
Q

Patient cooperation and dolls head

A

Not necessary and can be used in unconscious patients and infants

58
Q

When is dolls head useful

A
  • In patietns that are too young uncooperative, or too sick to respond to extraocular muscle testing
  • when vestibular dysfunction is suspected
  • contraindicated in trauma patietns with possible cervical spine injuries
59
Q

Caloric testing

A

If dolls head is contraindicated, a stronger stimulus can be provided in caloric testing to provoke the VOR

60
Q

Use of warm and cold water to set up temperature gradients in the semicircular canal causing a convection current int he endolymph then stimulating the hair cells

A

Caloric testing

61
Q

Patients head angle in caloric testing

A

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

62
Q

When is dolls head maneuver contraindicated

A

In trauma patietns with possible cervical spine injuries

63
Q

What happens when you put cold water in the ear in caloric testing

A

With cold water, normal response is nystagmus with fast phase towards the opposite ear

64
Q

Warm water normal response in caloric testing

A

Produces a fast phase towards the ipsilateral ear

65
Q

Mnemonic for caloric testing

A

COWs
Cold-opposite
Warm same

66
Q

Responsible for continuous eye movements after brief head movements (VOR is for brief movements)

A

Optokinetic relfex

67
Q

When does the optokinetic reflex kick in

A

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

68
Q

Holds image of the world steady on the retina during SUSTAINED head movement

A

Optokinetic reflex

69
Q

Which is for brief head movements

A

VOR

70
Q

Which is for sustained head movements

A

Optokinetic reflex

71
Q

When does optokinetic refelx take over

A

After brief head movements, because now it is sustained and continuing to move

72
Q

The patient is slowly rotates in a chair for about 20 seconds. The doctor pays attention to the eyes

A

Roatational testing

73
Q

Normal response in rotational testing

A

Slow conjugate eye movement than fast phase opposite the rotation of the chair

Spinning someone in a chair

74
Q

A slow pursuit eye movement followed by a fast corrective saccade because oa visual field moves over the retina

A

Optokinetic nystagmus (OKN)

75
Q

The fast corrective saccade during OKN

A

To fixate on a new stripe

76
Q

Head during the OKN

A

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

77
Q

What does the OKN require

A

Input from the visual system, not like the VOR that doesn’t

The OKN drum

78
Q

Latency in OKN

A

Longer

79
Q

OKN slow phase on the drum

A

Slow phase in the direction of the drum rotation

80
Q

When is OKN developed

A

At about 3-5 months of age

81
Q

What is OKN used for

A

Malingering and uncooperative patients

82
Q

Positive OKN response

A

Means that the VA is at or better than the size of the stripes

83
Q

Negative response on OKN

A

Inconclusive

84
Q

How to sue the OKN drum

A
  • patient seated
  • hold drum at eye level, at about 40-50cm from patient
  • tell patient to look at stripes
  • test OKN in both horizontal and vertical
  • spin the drum at a steady speed. Make sure it is not too fast so the stripes don’t blur
  • unfortunately there is not standard speed, stripe size or accurate correlation to VA
85
Q

OKN can sustained fixation for how many seconds

A

All patients, except very young, anxious, hyperactive and/or inattentive should be able to sustain fixation for 10 seconds

86
Q

Ocular motor disorders and the importance of these OKN eye movements (or versions in general)

A

Show serious neurological, functional, or developmental problems. Difficulty with pursuits and saccades could be seen in children with difficulty reading because the smaller, mroe fixations and regressions

May require a neurological consultation

87
Q

Evaluation of saccadic eye movements

A

NSUCO
DEM
King Devick
Visagraph

88
Q

Evaluate of pursuits

A

NSUCO

Groffman tracings

89
Q

Important to ensure I foveal fusion and eliminate diplopia that could occur because of images falling on retinal points that do not correpsond

A

Vergences

90
Q

These “compensatory” fusional movements occur when the disparity exceeds that Panum’s vision area. A sensory and motor fusion occurs

A

Vergences

91
Q

Zone of disparity, if not exceeded, still allows fusion of disparate points

A

Panum’s fusion

92
Q

Types of vergences

A

Tonic
Proximal
Fusional
Accommodative

93
Q

Require attention and cooperation of the cerebral cortex

A

Fusional vergences

94
Q

Elicited because of a disparity or a variation in the images at the retina

A

Fusional vergences

95
Q

Example of fusional vergences

A

When an object is moveing 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

96
Q

Constant innervation tone to the EOMs when awake and alert

A

Tonic vergence

97
Q

Naturally because of the anatomy of the orbit, eyes are divergent as we can see in unconscious patients

A

Tonic vergence

98
Q

What are tonic vergences needed for

A

To hold the eyes straight when eyes are at rest

99
Q

Induced convergence movement due to the awareness of near

A

Proximal (con)vergence

100
Q

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

A

Accommodative vergences

101
Q

Abnormally high AC/A

A

Can produce AT with accommodation

102
Q

Abnormally low AC/A

A

Makes it harder to converge, less esotropia, more exotropic

103
Q

Purpose of vergences

A

To ensure bifoveal fixation

104
Q

Do vergences require stimuli?

A

Yes

105
Q

Is there a response to target with vergences

A

Yes

106
Q

Purpose of saccades

A

Fast refixation on the new target

107
Q

Saccades: voluntary or involuntary?

A

Voluntary (and reflexive)

108
Q

Development of saccades

A

By 1 year

109
Q

Targets for saccades

A

Response to target movement

110
Q

Speed of saccade

A

400-700/sec

111
Q

Purpose of pursuits

A

Eyes follow moving target to maintain image on retina

112
Q

Voluntary or involuntary: pursuits

A

Involuntary

113
Q

Speed of pursuits

A

30-60 degree/sec

114
Q

Target and pursuit

A

Eyes more with the target

115
Q

Development of pursuits

A

3-4 months

116
Q

Targets and pursuits

A

Responses to target movement

117
Q

Purpose of VOR

A

Stabilizes retinal image during brief head roataion.

118
Q

Does VOR require stimuli

A

No, can work in the dark

119
Q

What does the VOR require input from

A

Semicircular canal of vestibular system

120
Q

How do eyes move relative to head in VOR

A

Opposite

121
Q

Speed of VOR

A

30-60 degrees per sec

122
Q

Purpose of OKR

A

Maintains stabilize retinal image during constant (sustained) head rotation

123
Q

OKR, voluntary or involuntary

A

Involuntary

124
Q

What does OKR respond to

A

Head movement

125
Q

Purpose of OKN

A

Keeps moving target on the fovea

126
Q

Is OKN voluntary of involuntary

A

Involuntary

127
Q

What does fast phase move relative to drum in OKN

A

Opposite the OKN drum

128
Q

When is OKN developed

A

3-5 months

129
Q

Speed of OKN

A

30-60 degrees/sec

Motility Block 9 (5 decks)

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