Intro to Eye Movements (M1) Flashcards Preview

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

Flashcards in Intro to Eye Movements (M1) Deck (75):
1

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

deorsumversion

2

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

visual axis

3

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

1. deosumduction (infraduction, depression)
2. 50 deg

4

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

Gaze shifting (saccades, pursuits and vergences)

5

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

1. right hypervergence
2. left hypovergence

6

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

1. longitude
2. latitude

7

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

versions

8

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

1. adductions
2. 50 deg

9

What is the angle between lines of sight called?

vergence angle

10

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

center of rotation of the eye (COR)

11

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

incyclovergence

12

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?

line of sight

13

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

lambda (λ)

14

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

visual axis

15

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

levocycloversion

16

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

secondary positions of gaze

17

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

vertical lines

18

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?

Listing's Plane

19

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?

pupillary axis

20

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

1. foveola
2. 70

21

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

extorsion

22

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

1. Helmholtz
2. horizontal (head)
3. vertical (eye)

23

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

1. Listing Coordinate system
2. axis angle and angle between primary gaze and final position

24

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

1. Azimuth
2. elevation

25

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

Fick

26

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

dextroversion

27

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

divergence

28

What are monocular eye rotations called?

ductions

29

What is the equation for the expected accommodative amplitude?

18.5 - 0.3*(age)

30

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

line of fixation

31

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

intorsion

32

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

1. 12.2mm behind corneal pole
2. eye's equator

33

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

levoversion

34

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

Park and Park

35

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

gamma (γ)

36

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

anatomical axis

37

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

1. Gaze-holding or Vestibulo-Ocular Reflex (VOR)
2. inner ear

38

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

dextrocycloversion

39

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

horizontal lines

40

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

1. Volkmann
2. sighting center

41

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

1. horizontal
2. vertical
3. torsion

42

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

convergence

43

How many seconds of arc are in one radian?

206,000

44

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

excyclovergence

45

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

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

46

What do the lines of sight form in the eye?

a caustic curve around the COR

47

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

sursumersion

48

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

vergences

49

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

1. 14.8mm behind corneal pole
2. 0.79mm nasal to lines of sight

50

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

Listing's law

51

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

1. abduction
2. 45 deg

52

How many minutes of arc are in a degree?

60

53

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

Fry

54

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

1. horizontal
2. vertical
3. torsion

55

What is Hering's Law?

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

56

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?

Donder's law

57

What is the main purpose of vergence eye movements?

image the object of regard on both foveas

58

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

false torsion

59

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

alpha (α)

60

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

primary position of gaze

61

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

Mueller

62

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

true torsion

63

What are the advantages of using two eyes in tandem?

1. inc ability to detect objects in low light levels
2. improved depth perception

64

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

accommodation

65

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

1. sursumduction (elevation)
2. 35 deg

66

What has torsion classically been measured with?

perceived afterimages

67

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

1. meridian
2. eccentricity
3. torsion

68

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

tangent screen or frontal parallel plane

69

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

1. fixational eye movements
2. nystagmus

70

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

1. Fick
2. vertical (head)
3. horizontal (eye)

71

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

optic axis

72

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

kappa (κ)

73

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

1. false torsion
2. true torsion

74

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

false torsion

75

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?

translations