Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OP2204- BV Lectures > 3 & 4. Extraocular Muscles And Ocular Motility > Flashcards

3 & 4. Extraocular Muscles And Ocular Motility Flashcards

1
Q

Explain the point centre of rotation in the eyeball?

A

This is the centre most point and all eyeball movements occur at this point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is centre of rotation in an eyeball?

A

Point that lies on the plane of equator.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the 3 axes that the eye rotates around?

A
  1. Z-axis: Horizontal rotation
  2. Y-axis/ optical axis: cyclorotation
  3. X-axis: vertical rotation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 axes of the eye called?

A

Axes of Fick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3 axes and centre of rotation lies on which plane?

A

Listings plane- imaginary plane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define Donder’s Law

A

That the orientation of the eye is always the same when the eye is aimed in a particular direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

For horizontal and vertical movements, is cyclo rotation involoved?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cyclo rotation only happens when looking where?

A

When looking at diagonal directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define listings law

A

Each movement of the eye from the primary position to any other position involves rotation around a single axis lying in the equatorial plane called listing’s plane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 monocular eye movements (Ductions)

A
  1. Lateral : Abduction- outwards, adduction- inwards
  2. Vertical: Depression- downwards, Elevation- upwards
  3. Rotational: Excycloduction- rotate outwards, Incycloduction- rotate inwards
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Lateral rectus is operated by? And this rectus rotates around which axis?

A

Operated by: 6th abducens nerve
Rotates around: z (vertical axis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Lateral rectus in primary position causes what action?

A

Abduction only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Lateral rectus in secondary position causes what action?

A

In elevation: some elevation
In depression: some depression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Medial rectus is operated by? And this rectus rotates around which axis?

A

3rd oculomotor nerve
Rotates around z axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Medial rectus in primary position causes what action?

A

Adduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Medial rectus in secondary position causes what action?

A

In elevation: some elevation
In depression: some depression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Superior rectus is operated by? And this rectus rotates around which axis?

A

3rd oculomotor nerve and rotates arround the z-axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Superior rectus in primary position causes what action?

A

1: Elevation
2: Incycloduction
3. Adduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Superior rectus in secondary position causes what action?

A

At 23 degrees: abduction: more elevation
At 67 degrees: adduction: more incycloduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Inferior rectus is operated by? And this rectus rotates around which axis?

A

3rd oculomotor nerve, rotates around x-y plane, 67 degrees nasal to y.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Inferior rectus in primary position causes what action?

A

1: Depression
2: Excycloduction
3: Adduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Inferior rectus in secondary position causes what action?

A

At 23 degrees: abduction: more depression
At 67 degrees: adduction: more excycloduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Superior oblique is operated by? And this rectus rotates around which axis?

A

4th (trochlear) nerve, rotates around x-y plane. 39 degrees temporal to y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Superior Oblique in primary position causes what action?

A

1: Incycloduction
2: depression
3: abduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Superior Oblique in secondary position causes what action?

A

At 51 degrees: adduction: more depression
At 39 degrees: abduction: more abduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Inferior oblique is operated by? And this rectus rotates around which axis?

A

3rd (oculomotor) nerve, rotates around x- y plane, 39 degrees temporal to y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Inferior Oblique in primary position causes what action?

A

1: Excycloduction
2: Elevation
3: Abduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Inferior Oblique in secondary position causes what action?

A

At 51 degrees: adduction- more elevation
At 39 degrees: abduction- more abduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is RADSIN?

A

Recti adduct (Superior and Inferior rectus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe what is vergence and versions

A

Vergence: movement of eyes in opposite directions, disjunctive
Versions: movement of eyes in the same direction, conjugate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Define ipsilateral antagonists, give an example

A

Pull one eye in opposite direction (when one muscle is relaxed and the other muscle is contracted). These muscles are found in pairs in the same eye.
Example: Right lateral contracts and right medial relaxes- when right eye looks to the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Define contralateral antagonists, give an example

A

When muscles are relaxed they move eyes in the same directions. Also known as yoke muscles.
Example: When looking to the right: Right and left medial muscle is relaxed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is sherrington’s law of reciprocal intervention, give an example

A

Increased innervation to a muscle is accompanied by a decrease in innervation in the ipsilateral antagonist.
Example: RLR contracts, RMR relaxes- when looking to your right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is herings law?

A

When innervation to a muscle changes, an equal change in innervation occurs in the contralateral synergist (innervation to right lateral rectus will result in equal innervation to the left medial rectus).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Sherrington’s law of reciprocal intervention and herings law all to binocular movements in which direction?

A

In ALL directions: Horizontal, vertical or diagonal versions and vergences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

The function of how many EOMs in each eye is tested?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is primary position?

A

When eyes are looking straight ahead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

We need to examine how many positions of gaze?

A

9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is secondary position?

A

Eyes straight up/ down/ right/ left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is tertiary position?

A

Eyes up and right/ up and left/ down and right/ down and left.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Describe the difference between Comitant and Incomitant

A

Comitant: deviation is manifest during testing an the deviation is the same in all directions. Incomitant: Deviation is manifest during test and deviation varies in different position of gaze.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

4 causes of incomtancy (congenital-4 and accquired-3)

A

Congenital: neurogenic, mechanical, myogenic, form (under development of nerve/ nucleus, birth trauma).
Acquired: Neurogenic, mechanical and myogenic.

42
Q

Hirschberg, krimsky and bruckers tests is sometimes referred to as?

A

Corneal Reflection (Reflex) tests

43
Q

What is anisometropia

A

Two eyes have different refractive powers

44
Q

Purpose of corneal reflection test

A
  1. Objective means of assessing ocular alignment
  2. Objective evaluation of anisometropia (bruckner)
45
Q

On what kind of patients is corneal reflection test performed?

A

It can be performed on all patients but most importantly used on patients who can’t cooperate with other tests e.g, babies

46
Q

How is Hirschberg test performed?

A

*Sit F2F with patient, straight ahead, same eye height
* Pen torch held so patient looking in primary position
(straight ahead, not up/down/left/right)
* Typically within arm’s length (so you can use prisms)
* If patient not automatically looking at light either make a noise or flash pen torch to get attention
* Observe corneal light reflections

47
Q

What are you looking at in Hirschberg test

A

If eyes are straight: Symmetrical Reflex; this test is used to find is patients have a tropia.

48
Q

Why does angle of Kappa exist

A

The visual axis doesn’t necessarily line up with the pupillary axis.

49
Q

What is positive angle Kappa?

A

When the corneal light reflex is nasal to the centre of the pupil

50
Q

Corneal diameter varies with?

A

Age

51
Q

Adult corneal diameter is?

A

11-13mm

52
Q

Corneal diameter from birth to 1 year old is?

A

9.5-11.5mm

53
Q

Each 1mm displacement for corneal reflex position is how many degrees?

A

7

54
Q

Variation in angle kappa could be due to?

A
  1. Space between eyes
  2. Rx
55
Q

What kind of symmetry is seen in patients with a phoria?

A

Symmetric reflections

56
Q

When is Krimsky Test done?

A

After Hirschberg

57
Q

Why is Hirschberg test done?

A

IF misalignments observed in Krimsky test, this test is done to measure the prism needed by the patient.

58
Q

How is Hirschberg test done?

A

Add prism in front of fixing eye- watch strabismic eye, increase prism until reflex in strabismic eye matches original symmetrical position of fixing eye.

59
Q

Describe the role of medial and lateral rectus? - in terms of eye movement

A

Medial Rectus: Move the eye inwards
Lateral Rectus: Move the eye outwards

60
Q

Ocular motility testing is used to assess?

A

Eye movements

61
Q

On the listings plane, y-axis is also known as?

A

Optical axis

62
Q

Monocular eye movements are called?

A

Ductions

63
Q

What is primary position?

A

When head is looking and eyes are looking straight

64
Q

Only the inferior rectus and inferior oblique?

A

Extort- turn the eyes out.

65
Q

Only superior rectus and superior oblique?

A

Intort: Turn the eyes in

66
Q

What is meant by EOM?

A

Extra ocular muscles

67
Q

Purpose of ocular motility?

A

This is an assessment of eye movements

68
Q

Monocular eye movements are known as?

A

Ductions

69
Q

What are the 3 types of ductions possible?

A
  1. Lateral
  2. Vertical
  3. Rotational
70
Q

What is primary position?

A

When head and eyes are looking straight ahead

71
Q

Why do some muscles have more then 1 action when they contract and other muscles don’t?

A

Horizontal, lateral and medial rectus muscles only have 1 action when they contract, because they lie along one of the rotation axes, other muscles don’t (other muscles lie oblique) hence they have more then 1 action.

72
Q

Identify the difference between Incyclovergence and Excyclovergence vs Dextrocycloversion and Levocycloversion

A

Incyclovergence: Both eyes turning in (eyes moving in opposite directions)
Excyclovergence: Both eyes turning out (eyes moving in opposite directions)
Dextrocycloversion: Both eyes moving in the same direction to the right
Levocycloversion: Both eyes moving in the same direction to the left

73
Q

What is meant by secondary position?

A

Eyes are looking straight up/ down/ right/ left

74
Q

Purpose of corneal reflection tests?

A

Objective means to assess ocular alignment and bruckers test is an objective evaluation of anisometropia

75
Q

What is the point of reference used to identify symmetry when doing the Hirschberg test?

A

The centre of the nose is used as a reference point

76
Q

Role/ function where bruckners test is most useful

A

In children to identify if they have anisometropia

77
Q

How is bruckners test performed?

A

Use ophthalmoscope at 0D. Sit far away from patient such that both eyes can be seen through the ophthalmoscope. Look at the red reflex reelection seen. This test is used to identify asymmetry between pupils and anisometropia.

78
Q

In bruckners test if asymmetry seen in corneal reflex this implies?

A

Strabismus

79
Q

In bruckners test if difference in brightness of fundus is observed, it is suggested?

A

Difference in refraction in both eyes

80
Q

In bruckners test if fundus reflex is elliptical, what does this suggest ?

A

Significant astigmatism

81
Q

In patients with black or white pupils seen in bruckner’s test, what does this suggest?

A

Black patches: could indicate cataract
White pupils: Retinoblastoma - in a young child. This needs urgent referral.

82
Q

What is the purpose of ocular motility test?

A

To assess ocular movements

83
Q

How is ocular motility testing done?

A
  1. Patients glasses off
  2. Sit at the same eye level with patient
  3. Patient to look straight ahead, observe for any AHP, if present correct it
  4. Pen torch, 50cm away
  5. Move light to 8 positions of gaze (3 secs out, 3 secs back).
84
Q

What observations are taken by asking patients questions, and how are these corrected?

A
  1. Ask patient if they can see 1 or 2 spots of light
  2. Ask patient if they are experiencing any pain or discomfort
  3. If vision gone double: can you make it single again?
  4. Are images side-by-side, or on top of each other?
85
Q

If a problem is identified in a position of gaze, what is done? - during ocular motility testing

A

Perform cover test in that position of gaze

86
Q

What is the next step if you identify that a patient has a strabismus only when they have the glasses off?

A

Assess if the deviation is comitant

87
Q

How does anisometropia affect test results?

A

One eye will accommodate more then the other eye as you switch between the 2 eyes.

88
Q

What is the impact on patients with a phoria seen while performing ocular motility test?

A

Patients may experience double vision, in extreme ends of gaze in almost all directions.

89
Q

What is an AV pattern?
Describe the A and V patterns

A

An increases or decrease in deviation as patients look in different direction of gazes.
A pattern: Patients have less deviation when they look up compared to when they look down.
V pattern: Patients have greater deviation when they look up compared to when they look down.

90
Q

Describe how prism cover test is performed

A
  1. Patient will hold fixation target at arms length.
  2. Place best estimated prism in front of the eye and repeat cover test till no movement is seen.
  3. Record results with size of deviation.
91
Q

Aim of performing prism cover test

A

Measure size of deviation

92
Q

How is the correct side of prism identified?

A

Image moves towards the apex

93
Q

How is base direction of prism identified?

A

Base goes in opposite direction to the movement of the eye.
Eye turned out: Base in

94
Q

Double maddox rod is a test for?

A

Cyclo deviation

95
Q

Are cyclo deviations symptomatic?
What muscles does this deviation affect?

A

Congenital are rarely symptomatic
Acquired are symptomatic
It generally affects oblique muscles could also be SR/ IR

96
Q

What happens to patients eyes and images in Excyclo-deviation and Incyclo-deviation

A

Excyclo-deviation: eyes turned out and image rotated inwards.
Incyclo-deviation: eyes tuned in and image rotated inwards.

97
Q

How is double maddox rod done?

A
  1. Spot light on
  2. Place 2 vertical maddox rods in patients trial frame: ideal if both different coloured.
    If no cyclo deviation: both lines are straight
    If cyclo deviation: lines tilted
98
Q

How to record patients with cyclo- deviation identified with maddox rod?

A

If patients sees tilted lines, turn the maddox rod in the frame until both lines are aligned, read and record the axis off from the trial frame.

99
Q

How to record patients with cyclo- deviation identified with maddox rod?

A

If patients sees tilted lines, turn the maddox rod in the frame until both lines are aligned, read and record the axis off from the trial frame.

100
Q

Optic nerve does not run straight through the orbit it is slightly curved, what is the benefit of this?

A

Allows eye movements

101
Q

Ocular motility tests?

A

Assessment of eye movements

102
Q

Muscles that move the eyes outwards are called?

A

Lateral rectus

OP2204- BV Lectures (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions