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methods BLOCK 2 > Cover test > Flashcards

Cover test Flashcards

1
Q

Cover test is done to determine…

A
  • presence of deviation (phoria or tropia)
  • laterality/which eye (unilateral or alternating)
  • frequency of the deviation (constant or intermittent)
  • direction of the phoria or tropia
  • magnitude (size) of the deviation
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2
Q

orthophoria

A

the perfect alignemtn in the absence of a stimulus for fixation

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3
Q

heterophoria/phoria

A

the tendency for the eyes to deviate when fusion is blocked

-a small phoria is common in most people; overcome by fusion

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4
Q

phoria with “posture” slightly inward

A

esophoria

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5
Q

phoria with “posture” slightly outward

A

exophoria

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6
Q

decompensating phoria

A

when motor function is no longer enough to overcome a phoria. discomfort or diplopia

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7
Q

heterotropia/tropia

A
  • manifest deviation
  • visual axes of both eyes do not intersect at fixation
  • leads to diplopia or suppression of the deviated eye
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8
Q

reasons for tropia

A
  • aniosmetropia
  • abnormality of the extraocular muscles or strabismus
  • eye disease
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9
Q

anisometropia

A

difference in refractive errors between the two eyes

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10
Q

cover-uncover test (unilateral cover test)

A
  • presence of deviation (phoria or tropia)
  • laterality/which eye (unliateral or alternating)
  • frequency of the deviation (constant or intermittent)
  • this test done FIRST
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11
Q

Which test should be done first?

A

cover-uncover test

-want to make sure you don’t break fusion

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12
Q

alternating cover test

A

determines:

  • direction of phoria or tropia
  • magnitude (aize) of the deviation
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13
Q

At what distance is the cover test done?

A

at distance and near

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14
Q

“Cover” in the cover-uncover

A
  • show if deviation is phoria or tropia
  • evaluates the visual axis of each eye when both eyes are viewing a target
  • look at eye that is NOT covered
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15
Q

phoria

A

the visual axis of both eyes are aligned on the target with both eyes open

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16
Q

tropia

A

the visual axis of both eyes is aligned on the target while the other is misaligned with both eyes open. Now it has to move to pick up fixation

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17
Q

“uncover” in cover test

A
  • shows if a tropia is alternating or unilateral (laterality)
  • shoes if a tropia is constant or intermittent (frequency)
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18
Q

unilateral tropia

A

R or L tropia is when one eye usually fixates when both eyes are open
-the tropic eye only fixates when the preferred fixating eye is occluding

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19
Q

alternating tropia

A

pt able to keep either eye on a target with both eyes open

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20
Q

equipment for cover test

A
  • VA chart
  • near point
  • occluder/paddle
  • prisms
  • habitual correction
  • well lit room
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21
Q

how do you explain purpose of cover test to patients?

A

“I want to make sure your eyes are aligned properly

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22
Q

How to do cover test

A
  • sit or stand in a way that you can see the eys but does not block pts fixation. Hold occluder and prisms
  • tell pt to look at target and keep it clear
  • determine if pt is able to fixate with the right eye when the left eye is covered, and then evaluate if the left eye is able to fixate when the right eye is covered
  • observe any movement as soon as the left eye is covered
  • allow 2-3s for eyes to ressume relationship with each other
  • repeat a few times
  • repaet with other eye
23
Q

How to do cover test at distance

A

-at distance, isolate letter that is 1 or 2 lines larger than the best corrected VA in the poorer seeing eye

24
Q

How to do a cover test at near

A
  • hold target at 40cm
  • leter 1-2 lines larger than BCVA of poor eye
  • target of comparable size. pt can hold target
25
Q

What does it mean if there is no movement in the eye if the other is occluded?

A

eye was fixating when both eyes were open. if its the same in both eyes with no movement it is phoria

26
Q

tropia

A

if there was any movement on unilateral cover test

27
Q

How do you determine if the tropia is unilateral or alternating?

A

observe the movement of the uncovered eye

28
Q

alternating cover test

A

determines the direction and the size of the deviation

29
Q

how to do alternating cover test

A
  • tell pt to look at target and keep it clear
  • place occluder in front of right eye for 2-3 seconds to break binocular fusion
  • quickly alternate and move the occluder to the left eye, observing right eye you just uncovered for directional movement

**watch uncovered eye for the refitting action and direction

30
Q

measuring the deviation

A
  • prism in front of one eye and watch the other
  • keep moving occluder back and forth while increasing prism until you no longer see movement
  • deviation is neutralized at the amount of prism where both eyes appear aligned and there is no more movement on alternate CT
31
Q

Exo

A

BI prism

32
Q

Eso

A

BO prism

33
Q

Hypo

A

BU prism

34
Q

Hyper

A

BD prism

35
Q

Ortho

A

verify by using BI and then BO

36
Q

recording tropia or phoria

A
  • cc/sc
  • distance and near findings separately. add prime (‘) for near results
  • amount of prism used to neutralize
  • direction of deviation
  • phoria or tropia
  • R/L for tropia
37
Q

E

A

esotropia/esophoria

38
Q

X

A

exotropia/exophoria

39
Q

RH

A

Right hypertropia/hyperphoria

40
Q

LH

A

left hypertropia/hyperphoria

41
Q

record Ortho

A

for no deviation

42
Q

when recording tropia

A
  • L/R
  • alt (alternating)
  • intermittent tropia (T)
  • amount of prism
43
Q

Horizontal phorias

A

usually not recorded like this sine the phoria is a relationship between the two eyes

44
Q

laterality

A

alternating

45
Q

frequency

A

intermittent

46
Q

magnitude

A

amount of prism

47
Q

presence of deviation

A

phoria/tropia

48
Q

CT cc 20PD RX(T) at N

A

Cover test with correction 20 prism diopters right intermittent exotropia at near

49
Q

expected finding

A

about 0-3 XP at N

50
Q

when recording…

A

mention presence, laterality, and frequency

51
Q

comitancy

A

deviation size remains same (or within 5pd) in all positions of gaze
-implying no muscles are underacting or overacting

52
Q

noncomitancy

A

deviation size changes in difference positions of gave

-due to an over action or under action of one of multiple muscles

53
Q

to determine comitancy

A

CT is done in all positions of gaze

methods BLOCK 2 (8 decks)

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