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PPO 1 > Cover Test and related topics > Flashcards

Cover Test and related topics Flashcards

Cover Test: Procedure Cover Test: Interpretation of Results Local Sign Corresponding Points Strabismus Amblyopia (intro)

1
Q

Where does the cover test get it’s name?

A

An occluder is used to COVER an eye

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2
Q

What is the purpose of the cover test?

A

To identify a “misalignment” of the eyes

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3
Q

Why is the cover test important?

A

Eye misalignment has the potential to lead to AMBLYOPIA in children

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4
Q

Where does fusion take place?

A

Neocortex in the central processing part of the fusional system

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5
Q

To have successful fusion, the brain has to interpret the info coming from the two eyes as coming from the same ________ AND ________.

A

visual target AND location

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6
Q

Retinal images and neural signals that the info (from the same visual target) causes must be ________ for fusion to be successful.

A

very simmilar

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7
Q

How does the brain “know” where something is located?

A

It interprets the object’s location according to the location of the object’s image on the retina, the “local sign.”

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8
Q

What is the Local Sign?

A

The location of the image of an object on the retina which allows the brain to interpret the location of the object.

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9
Q

When the retinal images in the two eyes have the same Local Sign, we say that the images are falling on ___________.

A

Corresponding Points

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10
Q

Target used for cover test has to have _____ visual detail.

A

fine

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11
Q

The cover tests are performed at distance, ___ ft, and at near, ___ cm.

A

20 ft and 40 cm

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12
Q

two parts of the cover test are…

A
  1. Unilateral or “Cover-Uncover Test”

2. Alternating Cover

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13
Q

First Law of the Unilateral Cover Test: An eye moves in order to _____, because it was not already ______.

A

fixate; fiaxting

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14
Q

Second Law of Cover Test: If an eye does not move, it was ________.

A

already fixating

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15
Q

When performing the Unilateral/Cover-Uncover Test, the eye that moves is said to have a _____.

A

tropia

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16
Q

When performing the Unilateral/Cover-Uncover Test, which eye do you look at/observe?

A

The eye that you are not covering; the other eye.

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17
Q 
Unilateral Cover Test Procedure:
1.
2.
3.
4.
5. Repeat on OS
A
  1. Cover the OD first while observing the OS
  2. Keep the occluder on for 2-3 seconds
  3. Remove the occluder for 2-3 seconds
  4. Repeat to make sure your observations were accurate and are confirmed
  5. Repeat on OS
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18
Q

Interpretation of the Unilateral Cover Test:
Cover OD while observing OS
OS did NOT move
Conclusion: _____________

A

No tropia in OS

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19
Q

Interpretation of the Unilateral Cover Test:
Cover OD while observing OS
OS DID move
Conclusion: _____________

A

Tropia in OS

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20
Q

Interpretation of the Unilateral Cover Test:
Cover Os while observing OD
OD did NOT move
Conclusion: _____________

A

No tropia in OD

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21
Q

Interpretation of the Unilateral Cover Test:
Cover OS while observing OD
OD DID move
Conclusion: _____________

A

Tropia in OD

22
Q

If a tropia is observed in both eyes during the Unilateral Cover Test, the patient has a/an _______.

A

Alternating tropia/strabismus

23
Q

What is the goal of the unilateral cover test?

A

To detect the presence or absence of strabismus.

24
Q

Define strabismus/tropia

A

Misalignment of an eye

25
Q

Define diplopia

A

Double vision

26
Q

Define amblyopia

A

Reduced vision not due to refractive error or pathology

27
Q

Two common causes of amblyopia are ______ and ____.

A
  1. strabismus/tropia

2. anisometropia

28
Q

A constant strabismus will result in either _____ or _____.

A

diplopia or suppression

29
Q

When suppression is prolonged, it becomes _____ and the VA in that eye is _____.

A

permanent and reduced

30
Q

Define bifixation

A

Each eye is fixating (looking at) the same target

31
Q

The alternating cover tests allows to check for _____.

A

phoria

32
Q

Define phoria

A

Misalignment of the eyes that is present ONLY when fusion is broken.

33
Q

Define “phoria position”

A

Position the eyes go to when fusion is broken

34
Q

At the beginning of the alternating cover test, where do you have the occluder positioned?

A

Occluder covers one eye to break fusion

35
Q

At the beginning of the unilateral cover test, where do you have the occluder positioned?

A

Occluder is to the side of the eye which you will then cover to break fusion

36
Q

Is phoria a property of one eye or both eyes?

A

Unlike strabismus, phoria is a property shared by two eyes.

37
Q

Define orthophoria

A

Phoria has a size of zero.

Even with fusion broken, the eye behind the occluder continues to point at the target, even though it can’t see the target through the occluder. The eyes remain aligned with each other.

38
Q

Define heterophoria

A

Any phoria other than zero.

With fusion broken, the eye behind the occluder no longer points directly at the target. The eyes are misaligned with each other when fusion is disrupted.

39
Q

Define exophoria

A

In the phoria position (when covered), the eye does not turn in (converge) enough to be pointing at the target. The direction of deviation is outward.

40
Q

How would you observe an exophoria?

A

When removing the occluder from the covered eye, the eye would be observed moving inward revealing that it was deviated outward.

41
Q

Define esophoria

A

In the phoria position (when covered), the eye does not turn out enough to be pointing at the target. It is converged too much. The direction of deviation is inward.

42
Q

How would you observe an esophoria?

A

When removing the occluder from the covered eye, the eye would be observed moving outward revealing that it was deviated inward.

43
Q

Define hyperphoria

A

Eye that is deviated upward

44
Q

Define hypophoria

A

Eye that is deviated downward

45
Q

When describing vertical deviations, you always specify both the ______ and the ____.

A

Direction and eye

46
Q

For vertical phorias, the convention is to always specify the _____ eye.

a. hyper
b. hypo

A

a. hyper

47
Q

When do you refer patients with phorias?

A

When the phoria is large or vertical

48
Q

Define exotropia

A

Occlusion of one eye causes the other eye to move medially. This eye that moves has an exotropia.

49
Q

Define esotropia

A

Occlusion of one eye causes the other eye to move laterally. This eye that moves has an esotropia.

50
Q

On the unilateral cover test, when you cover the patient’s OD, his OS does not move. When you cover his OS, his OD does move. What kind of deviation does he have?

A

Right tropia

51
Q

During the ACT, when you move your occluder quickly from the OD to OS, you see the OD move inward. When you move your occluder quickly from the OS back to the OD, you see the OS move inward. This patient has a

A

exophoria

PPO 1 (3 decks)

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