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Clinical Methods II > Vergence > Flashcards

Vergence Flashcards

1
Q

maddox’s 5 components of vergence are:

A
  • tonic
  • proximal
  • voluntary
  • accommodative
  • disparity
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2
Q

the response in the absence of stimulus is called _____ vergence

A

tonic

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3
Q

tonic vergence is about ____ prism diopters of convergence

A

2-4 prism diopters of convergence

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4
Q

_____ convergence is driven by perception of nearness of an object (less than 3 meters)

A

proximal convergence

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5
Q

_____ vergence is driven by voluntary effort (on purpose)

A

voluntary

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6
Q

____ vergence is driven by accommodation and an important component of the near response

A

accommodative vergence

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7
Q

AC/A ratio is

A

accommodation convergence per unit of accommodation (in prism diopters / diopter)

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8
Q

______ AC/A ratio assumes a perfect response to accommodation

A

stimulus

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9
Q

______ AC/A ratio is more accurate

A

response

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10
Q

_____ AC/A ratio is usually 10% less than the ______ AC/A ratio

A

response is 10% less than stimulus

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11
Q

accommodative convergence can provide over _____ of the required convergence at near

A

a half

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12
Q

high AC/A ratio means

A

AC can provide much more

-eso at near

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13
Q

low AC/A ratio means

A

AC can provide much less
-exo at near
(more common)

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14
Q

AC/A ratio is responsible for patient’s ____ ______

A

near phoria

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15
Q

______ vergence is driven by binocular disparity, and has closed-loop negative feedback control
(also called fusion or reflex)

A

disparity

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16
Q

uncrossed retinal disparity requires _____ for fusion

A

divergence

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17
Q

crossed retinal disparity requires _____ for fusion

A

convergence

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18
Q

object images on the foveal have ____ disparity

A

0

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19
Q

_____ is responsible for the patient’s near phoria

A

AC/A ratio

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20
Q

_____ is responsible for the patient’s distance phoria

A

tonic vergence

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21
Q

phasic controller element is the:

A

fast component of disparity vergence

22
Q

tonic adaptive controller element is the:

A

slow component for disparity vergence

23
Q

problems with what can lead to asthenopia (eye strain)?

A

tonic adaptive controller element (slow component to disparity vergence)

24
Q

negative fusional vergence uses ___ prism and tests ____

A

base in (BI) to test divergence

25
Q

positive fusional vergence uses ___ prism and tests _____

A

base out (BO) to test convergence

26
Q

adding ___ prism stimulates accommodation therefore accommodation must relax

A

BO (convergence)

27
Q

adding ___ prism inhibits accommodation therefore accommodation must stimulate

A

BI (divergence)

28
Q

what does the blur point represent?

A

the fusional vergence without the effects of accommodation

29
Q

what kind of fusional vergence amplitudes are associated with less asthenopia?

A

larger fusional vergences

30
Q

why are larger fusional vergences associated with less asthenopia?

A

they can compensate for larger phorias

31
Q

the break point is a measure of

A

the amount of fusional vergence that is not independent of accommodation

32
Q

the total demand on the fusional vergence system is the:

A

phoria plus the compensating vergence

33
Q

interval between 0 and the blue point (or break if no blur occurs) = ______ vergence

A

relative

34
Q

interval between the phoria and the blue point in the opposite direction = ______ vergence

A

fusional

35
Q

blur point is from _____ vergence only

A

fusional vergence only

vergence independent of accommodation

36
Q

what does accommodation do after blur?

A

after blur, accommodation contributes to the vergence response

37
Q

when can you analyze using Morgan’s data?

A

if no or low phoria (1EP-1XP at far) or (0-6XP at near)

38
Q

PFV compensates for:

A

XP

39
Q

NFV compensates for:

A

EP

40
Q

right infravergence compensates for

A

right hyperphoria

41
Q

Sheard’s criterion states that

A

relative vergence reserve needs to be at least twice the demand

42
Q

Sheard’s criterion is a good predictor of symptoms in

A

moderate to high XP

43
Q

Percival’s criterion is a better predictor of symptoms in cases of

A

esophoria

moderate

44
Q

Percival’s criterion states

A

the lower magnitude vergence should be at least 1/2 of the higher magnitude vergence

45
Q

using prism as a treatment option causes:

A

decreases the vergence demand

46
Q

what is the net result from using prism as a treatment option

A

smaller phoria and larger compensating ranges

47
Q

what prism would be used for esophoria

A

base out prism

48
Q

what prism would be used for exophoria

A

base in prism

49
Q

addition lenses at near would be a useful treatment option for:

A

esophoria at near

50
Q

addition lenses at near can cause:

A

decreases accommodative demand which then decreases accommodative-convergence

Clinical Methods II (7 decks)

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