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Motility Block 9 > Ductions And Versions > Flashcards

Ductions And Versions Flashcards

(129 cards)

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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
Saccades in infants
Can start in infants, but it is inaccurate, Kelly movment until the target is reached
26
When are saccades well developed
By 1 year of age
27
Examples of saccadic eye movements
- response to commands - fast phase during optokinetic or vestibular movements - R.E.M. During sleep - correcting saccades during fast pursuits - microsaccades
28
Faster than pursuits and vergences
Saccades
29
Are saccades voluntary or involuntary
Voluntary, but there can be reflex saccades with sudden visual, auditory, or peripheral stimuli
30
Brings image to fovea
Saccades
31
Maintains the fovea conjugately on a slowly moving target. Stimulus is a target moving in the parafovea
Pursuits
32
Latency of pursuits
Shorter than saccades- meaning faster to start
33
Peak velocity of pursuits
30-60 degrees/dec
34
Helps match eye velocity to target velocity
Pursuits
35
Used in involuntary optokinetic movements to track a moving object and then refixate with a compensatory saccade to refixate
Pursuits
36
When are smooth pursuits better developed
Are better developed by the 3rd and 4th month of life
37
Which is quicker to start? Pursuit or saccade
Pursuit
38
Shorter latency, pursuit or saccade
Pursuit
39
Faster velocity, saccade or pursuit
Saccade
40
Involuntary, pursuit or saccade
Pursuit
41
Holds image of slow moving target on fovea
Pursuits
42
If target velocity increases during pursuits
Pursuit breaks into a jerky movement since it has a velocity of only 30-60/sec
43
Latency of pursuits
125ms
44
What are pursuit scontrolled by
Ipsilateral parietal lobe | -right pursuit driven by right parietal lobe
45
These movements stabilize a retinal image during brief head movement
Vestibulocochlear-ocular reflex (VOR)
46
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)
Vestibular ocular reflex
47
Does the VOR require stimuli
No. Can occur with the eyes close and even in the dark (since it is a response to head movement)
48
VOR at birth
Horizontal VOR is well developed at birth, while vertical VOR developes later
49
In VOR, what is moveing?
The head, not the target
50
Holds the image steady during brief head movement
VOR
51
Vergence or versions for VOR
Versions
52
Produces eye movement of equal magnitude to head movement but in opposite direction
VOR
53
What doe doll head result in
Conjugate eye movement opposite to the head movement
54
What causes horizontal nystagmus
Vestibular damage
55
Dolls head maneuver or oculocephalic maneuver
Patient fixates on an image while the examiner quickly rotates the head in the horizontal plane and then in the vertical plane
56
Normal VOR in dolls head
Results in eye movements that are equal and opposite to the head movement
57
Patient cooperation and dolls head
Not necessary and can be used in unconscious patients and infants
58
When is dolls head useful
- 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
Caloric testing
If dolls head is contraindicated, a stronger stimulus can be provided in caloric testing to provoke the VOR
60
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
Caloric testing
61
Patients head angle in caloric testing
Angled at 30 degrees so the horizontal semicircular canal is perpendicular to the floor
62
When is dolls head maneuver contraindicated
In trauma patietns with possible cervical spine injuries
63
What happens when you put cold water in the ear in caloric testing
With cold water, normal response is nystagmus with fast phase towards the opposite ear
64
Warm water normal response in caloric testing
Produces a fast phase towards the ipsilateral ear
65
Mnemonic for caloric testing
COWs Cold-opposite Warm same
66
Responsible for continuous eye movements after brief head movements (VOR is for brief movements)
Optokinetic relfex
67
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)
68
Holds image of the world steady on the retina during SUSTAINED head movement
Optokinetic reflex
69
Which is for brief head movements
VOR
70
Which is for sustained head movements
Optokinetic reflex
71
When does optokinetic refelx take over
After brief head movements, because now it is sustained and continuing to move
72
The patient is slowly rotates in a chair for about 20 seconds. The doctor pays attention to the eyes
Roatational testing
73
Normal response in rotational testing
Slow conjugate eye movement than fast phase opposite the rotation of the chair Spinning someone in a chair
74
A slow pursuit eye movement followed by a fast corrective saccade because oa visual field moves over the retina
Optokinetic nystagmus (OKN)
75
The fast corrective saccade during OKN
To fixate on a new stripe
76
Head during the OKN
A conjugate movement maintinaing the image of the moving target on the fovea when the head is still
77
What does the OKN require
Input from the visual system, not like the VOR that doesn't The OKN drum
78
Latency in OKN
Longer
79
OKN slow phase on the drum
Slow phase in the direction of the drum rotation
80
When is OKN developed
At about 3-5 months of age
81
What is OKN used for
Malingering and uncooperative patients
82
Positive OKN response
Means that the VA is at or better than the size of the stripes
83
Negative response on OKN
Inconclusive
84
How to sue the OKN drum
- 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
OKN can sustained fixation for how many seconds
All patients, except very young, anxious, hyperactive and/or inattentive should be able to sustain fixation for 10 seconds
86
Ocular motor disorders and the importance of these OKN eye movements (or versions in general)
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
Evaluation of saccadic eye movements
NSUCO DEM King Devick Visagraph
88
Evaluate of pursuits
NSUCO | Groffman tracings
89
Important to ensure I foveal fusion and eliminate diplopia that could occur because of images falling on retinal points that do not correpsond
Vergences
90
These "compensatory" fusional movements occur when the disparity exceeds that Panum's vision area. A sensory and motor fusion occurs
Vergences
91
Zone of disparity, if not exceeded, still allows fusion of disparate points
Panum's fusion
92
Types of vergences
Tonic Proximal Fusional Accommodative
93
Require attention and cooperation of the cerebral cortex
Fusional vergences
94
Elicited because of a disparity or a variation in the images at the retina
Fusional vergences
95
Example of fusional vergences
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
Constant innervation tone to the EOMs when awake and alert
Tonic vergence
97
Naturally because of the anatomy of the orbit, eyes are divergent as we can see in unconscious patients
Tonic vergence
98
What are tonic vergences needed for
To hold the eyes straight when eyes are at rest
99
Induced convergence movement due to the awareness of near
Proximal (con)vergence
100
A consistent increment of accommodative convergence happens with each diopter of accommodation giving the AC/A ratio
Accommodative vergences
101
Abnormally high AC/A
Can produce AT with accommodation
102
Abnormally low AC/A
Makes it harder to converge, less esotropia, more exotropic
103
Purpose of vergences
To ensure bifoveal fixation
104
Do vergences require stimuli?
Yes
105
Is there a response to target with vergences
Yes
106
Purpose of saccades
Fast refixation on the new target
107
Saccades: voluntary or involuntary?
Voluntary (and reflexive)
108
Development of saccades
By 1 year
109
Targets for saccades
Response to target movement
110
Speed of saccade
400-700/sec
111
Purpose of pursuits
Eyes follow moving target to maintain image on retina
112
Voluntary or involuntary: pursuits
Involuntary
113
Speed of pursuits
30-60 degree/sec
114
Target and pursuit
Eyes more with the target
115
Development of pursuits
3-4 months
116
Targets and pursuits
Responses to target movement
117
Purpose of VOR
Stabilizes retinal image during brief head roataion.
118
Does VOR require stimuli
No, can work in the dark
119
What does the VOR require input from
Semicircular canal of vestibular system
120
How do eyes move relative to head in VOR
Opposite
121
Speed of VOR
30-60 degrees per sec
122
Purpose of OKR
Maintains stabilize retinal image during constant (sustained) head rotation
123
OKR, voluntary or involuntary
Involuntary
124
What does OKR respond to
Head movement
125
Purpose of OKN
Keeps moving target on the fovea
126
Is OKN voluntary of involuntary
Involuntary
127
What does fast phase move relative to drum in OKN
Opposite the OKN drum
128
When is OKN developed
3-5 months
129
Speed of OKN
30-60 degrees/sec

Motility Block 9 (5 decks)

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