Cover Test and related topics

Question 1

Where does the cover test get it’s name?

Answer 1

An occluder is used to COVER an eye

Question 2

What is the purpose of the cover test?

Answer 2

To identify a “misalignment” of the eyes

Question 3

Why is the cover test important?

Answer 3

Eye misalignment has the potential to lead to AMBLYOPIA in children

Question 4

Where does fusion take place?

Answer 4

Neocortex in the central processing part of the fusional system

Question 5

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

Answer 5

visual target AND location

Question 6

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

Answer 6

very simmilar

Question 7

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

Answer 7

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

Question 8

What is the Local Sign?

Answer 8

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

Question 9

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

Answer 9

Corresponding Points

Question 10

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

Answer 10

fine

Question 11

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

Answer 11

20 ft and 40 cm

Question 12

two parts of the cover test are…

Answer 12

1. Unilateral or “Cover-Uncover Test”

2. Alternating Cover

Question 13

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

Answer 13

fixate; fiaxting

Question 14

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

Answer 14

already fixating

Question 15

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

Answer 15

tropia

Question 16

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

Answer 16

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

Question 17

Unilateral Cover Test Procedure:
1.
2.
3.
4.
5. Repeat on OS

Answer 17

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

Question 18

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

Answer 18

No tropia in OS

Question 19

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

Answer 19

Tropia in OS

Question 20

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

Answer 20

No tropia in OD

Question 21

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

Answer 21

Tropia in OD

Question 22

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

Answer 22

Alternating tropia/strabismus

Question 23

What is the goal of the unilateral cover test?

Answer 23

To detect the presence or absence of strabismus.

Question 24

Define strabismus/tropia

Answer 24

Misalignment of an eye

Question 25

Define diplopia

Answer 25

Double vision

Question 26

Define amblyopia

Answer 26

Reduced vision not due to refractive error or pathology

Question 27

Two common causes of amblyopia are ______ and ____.

Answer 27

1. strabismus/tropia | 2. anisometropia

Question 28

A constant strabismus will result in either _____ or _____.

Answer 28

diplopia or suppression

Question 29

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

Answer 29

permanent and reduced

Question 30

Define bifixation

Answer 30

Each eye is fixating (looking at) the same target

Question 31

The alternating cover tests allows to check for _____.

Answer 31

phoria

Question 32

Define phoria

Answer 32

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

Question 33

Define "phoria position"

Answer 33

Position the eyes go to when fusion is broken

Question 34

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

Answer 34

Occluder covers one eye to break fusion

Question 35

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

Answer 35

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

Question 36

Is phoria a property of one eye or both eyes?

Answer 36

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

Question 37

Define orthophoria

Answer 37

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.

Question 38

Define heterophoria

Answer 38

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.

Question 39

Define exophoria

Answer 39

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.

Question 40

How would you observe an exophoria?

Answer 40

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

Question 41

Define esophoria

Answer 41

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.

Question 42

How would you observe an esophoria?

Answer 42

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

Question 43

Define hyperphoria

Answer 43

Eye that is deviated upward

Question 44

Define hypophoria

Answer 44

Eye that is deviated downward

Question 45

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

Answer 45

Direction and eye

Question 46

For vertical phorias, the convention is to always specify the _____ eye. a. hyper b. hypo

Answer 46

a. hyper

Question 47

When do you refer patients with phorias?

Answer 47

When the phoria is large or vertical

Question 48

Define exotropia

Answer 48

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

Question 49

Define esotropia

Answer 49

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

Question 50

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?

Answer 50

Right tropia

Question 51

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

Answer 51

exophoria