Vergence Eye Movements and the ZCSBV (M2) Flashcards Preview

III. Binocular Vision > Vergence Eye Movements and the ZCSBV (M2) > Flashcards

Flashcards in Vergence Eye Movements and the ZCSBV (M2) Deck (62):
1

What is the accommodative response for an 1D myope wearing no Rx at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 1.50D
3. 1.00D
4. clear

2

What is the accommodative response for an 1D hyperope wearing no Rx at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 1.00D
2. 3.50D
3. clear
4. clear

3

How is the rate of accommodative convergence usually shown? 1. What are the two types of these? 2. What is a average value? 3

1. AC/A (accom conv/accom)
2. calculated (far-near) AC/A and Gradient AC/A
3. 4 pd/D

4

What does placing prisms and lenses effect relative to the ZCSBV?

does not effect zone at all, only effects demand

5

What is the line measured from the phoria line to the right-hand boundary of ZCSBV?

positive fusional vergence (PFV)

6

What are the four components that combine to make the total convergence?

1. fusional (disparity) vergence
2. accommodative vergence
3. proximal vergence
4. tonic vergence

7

What are the average distance phoria values? 1. Average near phoria values? 2

1. 1pd exo
2. 3pd exo

8

What is the latency of fusional vergence?

160ms

9

For an esophoria, what type of fusional convergence is used to compensate? 1. Exophoria? 2

1. negative fusional convergence
2. positive fusional convergence

10

What do the vergence ranges mark?

zone of clear single binocular vision

11

What is the line measured from the phoria line to the left-hand boundary of ZCSBV?

negative fusional vergence (NFV)

12

What is the binocular oculocentric direction for each eye after uncovering the right eye during the unilateral cover test with the presence of a esophoria?

beta left = 0
beta right = phoria angle

13

What is the accommodative response for an 3D myope wearing -2.00D at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 1.50D
3. 1.00D
4. clear

14

What are the theories of how the oculocentric directions are combined in binocular vision?

1. dominant eye theory (one is suppressed) = not what happens
2. cyclopean theory (betas averaged) = what actually happens

15

What is the idea that asymptomatic binocular vision occurs when the vergence demand is within the middle third of the total fusional vergence range? 1. Is this a better predictor of symptoms with esophoria or exophoria? 2

1. Percival's criterion
2. esophoria

16

What is the vergence position of the eyes in the absence of fusional vergence called?

phoria (dissociated phoria)

17

When patients have positive convergence deficiency, is the CA/C usually high or low?

high

18

What is the only information available to calculate and program the magnitude and direction of the required saccade when a person is monocular?

oculocentric direction (beta)

19

What happens when you decrease the convergence demand by putting a base in prism in front of a patient?

1. negative fusional vergence creates negative conv accom
2. negative conv accom can cause blur
3. at limit of NFV, most patients will decrease accommodation in order to release accommodative convergence
4. when run out of NFV and accom conv = double

20

What is the visual direction of an object specified relative to the line of fixation?

oculocentric direction (beta)

21

What is the accommodative demand equal to in general terms? 1. What also needs to be accounted for? 2

1. 1/distance
2. refractive error and refractive correction

22

For what patients is the demand line never in the ZSCBV?

strabismic patients

23

What is the idea that asymptomatic binocular vision occurs when the compensating fusional reserve is at least double the magnitude of the phoria? 1. Is this a better predictor of symptoms with esophoria or exophoria? 2

1. Sheard's criterion
2. exophoria

24

What are the eye movements that occur when uncovering the right eye during the unilateral cover test with the presence of a esophoria?

1. binocular disparity causes negative fusional vergence (divergence of both eyes)
2. left now off target (oculocentric direction not 0) so rightward conjugate eye movement (saccade) required to maintain foveal fixation
3. divergence to foveate

25

What can counteract positive convergence accommodation?

negative blur accom

26

What needs to be indicated about a strabismus?

1. frequency (constant or intermittent)
2. laterality (right, left, alternating)
3. direction (eso, exo, hyper, hypo)

27

What is the baseline value in the absence of any stimulus to accommodation called? 1. What is average? 2

1. tonic accommodation
2. 1.5D

28

What does putting plus lenses for reading is order to manage inadequate negative vergence do?

1. decrease accommodative demand
2. decrease blur accom
3. decrease accom conv

29

What is the accommodative response for an emmetrope wearing +2.00D at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 0.50D
3. 2.00D
4. clear

30

What are the techniques to manage patients with inadequate negative vergence?

1. prescribe plus lenses
2. prescribe vision therapy to increase compensating range
3. prescribe BO prism

31

What is the accommodative response for an 2D hyperope wearing +2.00D at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 2.50D
3. clear
4. clear

32

What is the accommodative response for an 3D myope wearing no Rx at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 0
3. 3.00D
4. 0.50D

33

What are the limitations of Percival's criterion?

1. does not consider the range of fusional vergence present
2. does not consider the magnitude or the direction of the phoria

34

What is the line measured from the demand line to the left-hand boundary of ZCSBV? 1. Are these BI or BO findings? 2

1. negative relative vergence (PRV)
2. BI

35

What is the component of fusional vergence that is used to change vergence posture? 1. Component used to hold vergence posture? 2

1. dynamic
2. static

36

What are the techniques to manage patients with inadequate positive vergence?

1. increase compensating vergence range by vision therapy/orthoptics
2. prescribe BI prism
3. prescribe minus lenses for reading

37

What are the normal BI vergence ranges for distance? 1. Near? 2

1. x/7/4
2. 13/21/13

38

What is the stimulus of fusional (disparity) vergence? 1. What is it controlled by? 2

1. binocular disparity
2. a feed-back loop

39

What indicates the ceiling of the ZSCBV?

amplitude of accommodation (AA)

40

What is the vergence posture in the absence of vergence stimulus called?

tonic vergence

41

What is the line measured from the demand line to the right-hand boundary of ZCSBV? 1. Are these BI or BO findings? 2

1. positive relative vergence (PRV)
2. BO

42

What are the eye movements that occur when covering the right eye during the unilateral cover test with the presence of a esophoria?

1. decay of NFV because covered causes both eyes to drift in
2. drift is stimulus for a pursuit to the left to foveate

43

What is the unilateral cover test used for?

to determine if there is a manifest deviation present (tropia/strabismus)

44

What is the blur finding when increasing the convergence demand considered? 1. What is the doubling finding considered? 2

1. limit of fusional vergence
2. limit of accommodative convergence

45

What is the plot of all combinations of accommodative and vergence demands that result in single clear vision?

zone of clear single binocular vision (ZCSBV)

46

What is the accommodative response for an 1D myope wearing -2.00D at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 1.00D
2. 3.50D
3. clear
4. clear

47

During the unilateral cover test, when uncovering an eye why does the vergence eye movement occur before the saccade?

shorter latency period

48

What are the normal BO vergence ranges for distance? 1. Near? 2

1. 9/19/10
2. 17/21/11

49

What are the methods to clinically measure a phoria?

1. alternating cover test
2. V-G phorias
3. Modified Thorington

50

What happens when you increase the convergence demand by putting a base out prism in front of a patient?

1. positive fusional vergence creates positive conv accom
2. Positive conv accom can cause blur
3. at limit of PFV, most patients will increase accommodation in order to drive accommodative convergence
4. when run out of PFV and accom conv = double

51

What are the criteria for a patient that is to receive minus lenses for reading is order to manage inadequate positive vergence?

need normal AC/A (not the case for most CI's)

52

What is the stimulus of blur (defocus) accommodation? 1. What is it controlled by? 2

1. retinal defocus
2. feed-back loop

53

What can meter angles be used for?

look at accommodation and vergence responses in similar units (diopters)

54

What test eliminates fusional vergence?

cover test

55

What is the angle between the lines of sight? 1. What is the equation for this? 2

1. vergence angle
2. VergAngle = pd/D

56

What is the rate of convergence accommodation measured in? 1. What is the normal range? 2

1. CA/C (Conv accom/conv)
2. 0.1 to 0.4 D/pd

57

What is the stimulus of for proximal vergence? 1. When can it effect clinical testing? 2

1. perceived distance of the target
2. mirror room, instrument (phoropter and auto refractor)

58

What does putting minus lenses for reading is order to manage inadequate positive vergence do?

1. increase accommodative demand
2. increase blur accom
3. increase accom conv

59

What are the components of ocular accommodation?

1. blur (defocus) accommodation
2. convergence accommodation
3. proximal accommodation
4. tonic accommodation

60

What is the accommodative response for an 0.50D hyperope wearing -5.00D at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 5.50D
2. 8.00D
3. clear
4. clear (b/c young)

61

What is the accommodative response for an emmetrope wearing no Rx at distance? 1. Near? 2. Amount of blur at distance? 3. Near? 4

1. 0
2. 2.50D
3. clear
4. clear

62

What is it called if the right eye goes down and the left eye goes down?

1. right hypervergence
2. left hypovergence