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III. Binocular Vision > Intro to Eye Movements (M1) > Flashcards

Intro to Eye Movements (M1) Flashcards

1
Q

What is the version that is a downward conjugate eye movement?

A

deorsumversion

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2
Q

What is the only axis that is the proper axis to describe a person’s direction of fixation if accommodation is fixed?

A

visual axis

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3
Q

What is the duction that rotates the eye downward called? 1. What is the limit? 2

A
  1. deosumduction (infraduction, depression)

2. 50 deg

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4
Q

What type of eye movements are purposeful shifts in gaze angle to bring the object of regard onto the fovea or maintain it?

A

Gaze shifting (saccades, pursuits and vergences)

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5
Q

If the right eye goes up and the left eye goes down, what is this called (both versions)?

A
  1. right hypervergence

2. left hypovergence

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6
Q

What are the Fick termed coordinates for horizontal movement? 1. Vertical movement? 2

A
  1. longitude

2. latitude

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7
Q

What is the binocular eye rotation that has the eyes moving in the same direction?

A

versions

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8
Q

What is the duction that rotates the eye nasally called? 1. What is the limit? 2

A
  1. adductions

2. 50 deg

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9
Q

What is the angle between lines of sight called?

A

vergence angle

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10
Q

What is a point within the eye that, during an eye movement, has zero velocity with respect to the orbit?

A

center of rotation of the eye (COR)

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11
Q

What is the vergence that rotates the eyes in toward the nose from the 12 o’clock position called?

A

incyclovergence

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12
Q

What is the chief ray of the eye that is from the fixation point to center of entrance pupil and from center of exit pupil to fovea?

A

line of sight

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13
Q

What is the angle between the line of sight and pupillary axis?

A

lambda (λ)

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14
Q

What axis is from the point of fixation to primary nodal point, then from the secondary nodal point to fovea?

A

visual axis

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15
Q

What is the version that is from the 12 o’clock position both eyes rotating to the left?

A

levocycloversion

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16
Q

What are the positions of gaze that are points along the horizontal and vertical axes from the primary position

A

secondary positions of gaze

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17
Q

Which lines are curved on a tangent screen for the Helmholtz coordinate system?

A

vertical lines

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18
Q

What is a plane passing through the head and COR of the eyes that is perpendicular to the line of sight when the eyes are in primary position?

A

Listing’s Plane

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19
Q

What is the line through the center of pupil that is normal to the cornea, through the center of curvature of cornea, and 7.8mm behind the corneal pole?

A

pupillary axis

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20
Q

Where is vision the best in the retina? 1. How many minutes of arc does it subtend? 2

A
  1. foveola

2. 70

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21
Q

What is the duction that rotates the eye away from the nose from the 12 o’clock position called?

A

extorsion

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22
Q

What is the reference system in which the vertical component is accounted for first, then the horizontal? 1. What is the primary axis (is this head or eye fixed)? 2. What is the secondary axis (is this head or eye fixed)? 3

A
  1. Helmholtz
  2. horizontal (head)
  3. vertical (eye)
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23
Q

What is the coordinate system for the eye that uses polar coordinates? 1. What are the coordinates for this system? 2

A
  1. Listing Coordinate system

2. axis angle and angle between primary gaze and final position

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24
Q

What are the Helmholtz termed coordinates for horizontal movement? 1. Vertical movement? 2

A
  1. Azimuth

2. elevation

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25
Q

What kind of coordinate system do most telescopes and camera tripods use?

A

Fick

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26
Q

What is the version that is a rightward conjugate eye movement?

A

dextroversion

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27
Q

What is the vergence that is an outward rotation about the vertical axis?

A

divergence

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28
Q

What are monocular eye rotations called?

A

ductions

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29
Q

What is the equation for the expected accommodative amplitude?

A

18.5 - 0.3*(age)

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30
Q

What is the axis from fixation point to center of rotation of eye?

A

line of fixation

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31
Q

What is the duction that rotates the eye toward the nose from the 12 o’clock position called?

A

intorsion

32
Q

Where did Fry find the COR to be for vertical movements?

A
  1. 12.2mm behind corneal pole

2. eye’s equator

33
Q

What is the version that is a leftward conjugate eye movement?

A

levoversion

34
Q

Who was it that concluded that the COR was moving in the eye and the orbit?

A

Park and Park

35
Q

What is the angle between the optic axis and line of fixation?

A

gamma (γ)

36
Q

What is the line joining corneal and scleral poles (not fovea)?

A

anatomical axis

37
Q

What type of eye movements counteract the “retinal slip” that occurs from head motion? 1. What are they controlled by? 2

A
  1. Gaze-holding or Vestibulo-Ocular Reflex (VOR)

2. inner ear

38
Q

What is the version that is from the 12 o’clock position both eyes rotating to the right?

A

dextrocycloversion

39
Q

Which lines are curved on a tangent screen for the Fick coordinate system?

A

horizontal lines

40
Q

Who was it that thought that the COR was 13.5mm behind the cornea? 1. What is this point now called? 2

A
  1. Volkmann

2. sighting center

41
Q

What are the three degrees of freedom to fully describe eye position and orientation for the Helmholtz coordinate system?

A
  1. horizontal
  2. vertical
  3. torsion
42
Q

What is the vergence that is an inward rotation about the vertical axis?

A

convergence

43
Q

How many seconds of arc are in one radian?

A

206,000

44
Q

What is the vergence that rotates the eyes out away from the nose from the 12 o’clock position called?

A

excyclovergence

45
Q

How much false torsion do each of the coordinate systems predict?

A
  1. Fick: none
  2. Helmholtz: most
  3. Listing: intermediate (most accurate)
46
Q

What do the lines of sight form in the eye?

A

a caustic curve around the COR

47
Q

What is the version that is a upward conjugate eye movement?

A

sursumersion

48
Q

What is the binocular eye rotation that has the eyes moving in opposite directions?

A

vergences

49
Q

Where did Fry find the COR to be for horizontal movements?

A
  1. 14.8mm behind corneal pole

2. 0.79mm nasal to lines of sight

50
Q

What states that any eye movement is equivalent to a single rotation about an axis in Listing’s plane?

A

Listing’s law

51
Q

What is the duction that rotates the eye temporally called? 1. What is the limit? 2

A
  1. abduction

2. 45 deg

52
Q

How many minutes of arc are in a degree?

A

60

53
Q

Who determined the COR was fixed in the orbit in front of the caustic curve from the lines of sight?

A

Fry

54
Q

What are the three degrees of freedom to fully describe eye position and orientation for the Fick coordinate system?

A
  1. horizontal
  2. vertical
  3. torsion
55
Q

What is Hering’s Law?

A

the ocular innervation during eye movements is such that the magnitude of rotation of the two eyes is equal

56
Q

What states that the orientation of the eye for a given gaze position is always the same and is independent of the path taken to this location?

A

Donder’s law

57
Q

What is the main purpose of vergence eye movements?

A

image the object of regard on both foveas

58
Q

What is torsion that occurs due to rotating the eye to a tertiary position called?

A

false torsion

59
Q

What is the angle between the optic axis and visual axis?

A

alpha (α)

60
Q

What is the position of gaze that is the straight ahead position?

A

primary position of gaze

61
Q

Who was it that first reasoned that the eye was in the center of the ball (eye)

A

Mueller

62
Q

What is torsion that occurs due to ocular rotation around an anterior-posterior axis called?

A

true torsion

63
Q

What are the advantages of using two eyes in tandem?

A
  1. inc ability to detect objects in low light levels

2. improved depth perception

64
Q

What type of eye movement is the changing in the shape of the crystalline lens to change the focal power of the eye?

A

accommodation

65
Q

What is the duction that rotates the eye upward called? 1. What is the limit? 2

A
  1. sursumduction (elevation)

2. 35 deg

66
Q

What has torsion classically been measured with?

A

perceived afterimages

67
Q

What are the three degrees of freedom to fully describe eye position and orientation for the Listing coordinate system?

A
  1. meridian
  2. eccentricity
  3. torsion
68
Q

What is the flat screen in which we specify the eye position and orientation?

A

tangent screen or frontal parallel plane

69
Q

What type of eye movements occur when attempting to hold gaze steady on a stationary object? 1. What is an abnormality of this? 2

A
  1. fixational eye movements

2. nystagmus

70
Q

What is the reference system in which the horizontal component is accounted for first, then the vertical? 1. What is the primary axis (is this head or eye fixed)? 2. What is the secondary axis (is this head or eye fixed)? 3

A
  1. Fick
  2. vertical (head)
  3. horizontal (eye)
71
Q

What axis joins the center of curvature of optical elements of the eye, the cornea, and lens?

A

optic axis

72
Q

What is the angle between the visual axis and pupillary axis?

A

kappa (κ)

73
Q

What does Listing’s law predict? 1. What does it not account for? 2

A
  1. false torsion

2. true torsion

74
Q

What can be defined as the difference in torsional position from that predicted by the Listing coordinate system?

A

false torsion

75
Q

What are linear motions of the eye whose effect on the eye rotation required to fixate an object decreases as the distance of the fixation point from the eye increases?

A

translations

III. Binocular Vision (15 decks)

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