Cover Test

Question 1

A cover test is used to determine:

Answer 1

• presence of a 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

Question 2

What is orthophoria?

Answer 2

The perfect alignment in the absence of a stimulus for fixation

Question 3

Define Heterophoria/phoria

Answer 3

The tendency for the eyes to deviate when fusion is blocked

Question 4

A small ___ is common in most people; overcome by fusion

Answer 4

phoria

Question 5

A “posture” slightly inward is _____

Answer 5

esophoria

Question 6

A “posture” slightly outward is ____

Answer 6

exophoria

Question 7

When motor fusion is no longer enough to overcome a phoria, it is called a _________ phoria.

Answer 7

decompensating

Question 8

A decompensating phoria could result in

Answer 8

discomfort or diplopia

-double VA may occur

Question 9

Hetertropia/Tropia is a _____ deviation

Answer 9

manifest

Question 10

_______ is when the visual axes of both eyes do not intersect at fixation.
Eye is NOT aligned properly

Answer 10

Heterotropia/Tropia

Question 11

Heterotropia/Tropia leads to

Answer 11

diplopia or suppression of the deviated eye

Question 12

A tropia could occur due to some of the following reasons:

Answer 12

• Ansiometropia (difference in refractive errors between the two eyes)
• Abnormality of the extraocular muscles or strabismus
• Eye disease

Question 13

Cover-Uncover Test (Unilateral Cover Test): Helps to differentiate:

Answer 13

• presence of a deviation (phoria/tropia)
• laterality/which eye (unilateral or alternating)
• frequency of the deviation (constant/intermittent)

Question 14

The cover-uncover test is done _____

Answer 14

first!

Question 15

Alternating cover test determines the:

Answer 15

• direction of the phoria/tropia

- magnitude (size) of the deviation

Question 16

Both Cover-Uncover (Unilateral Cover Test) and Alternating Cover Tests are performed at

Answer 16

distance AND near

Question 17

What does the “cover” show in the Cover-Uncover Test?

Answer 17

If the deviation is a phoria or a tropia

presence

Question 18

___ in Cover-Uncover evaluates the visual axis of each eye when both eyes are viewing a target.

Answer 18

“Cover”

Question 19

In the Cover-Uncover test, which eye do you look at?

Answer 19

The eye that is NOT covered

Question 20

In a Cover-Uncover Test:

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

Answer 20

Phoria

Question 21

In a Cover-Uncover Test:

___ is where the visual axis of one eye is aligned on the target while the other is misaligned with both eyes open. It will have to move to pick up fixation.

Answer 21

Tropia

Question 22

“Uncover” in a Cover-Uncover Test shows

Answer 22

• if a tropia is alternating or unilateral tropias (Lateralitly)
• if a tropia is constant or intermittent (frequency)

Question 23

For “Uncover” in a Cover-Uncover Test, you focus on the eye

Answer 23

that is NOT occluded to determine if it picks up fixation.

Question 24

“Uncover” in Cover-Uncover Test:

A(n) _____ tropia is when one eye usually fixates when both eyes are open.

Answer 24

unilateral (right or left)

Question 25

For a unilateral (right or left) tropia, the tropic eye

Answer 25

only fixates when the preferred fixating eye is occluded

Question 26

A(n) _______ tropia is when the patient is able to keep either eye (visual axis) on a target with both eyes open.

Answer 26

alternating

Question 27

Equipment needed for Cover Tests: (6 things)

Answer 27

1) Visual Acuity Chart for Fixation at distance 2) Near Point Target for Fixation at near 3) Occluder/paddle 4) Horizontal and vertical prism bars or loose prisms 5) Habitual Correction (CT will be done with and without correction in some cases) 6) Well lit room

Question 28

How do you explain the purpose of the Cover Test(s) to your patient?

Answer 28

"I want to make sure your eyes are aligned properly."

Question 29

For a cover test at distance,

Answer 29

isolate a letter that is 1-2 lines larger than the best corrected visual acuity (BCVA) in the poorer seeing eye.

Question 30

For a cover test at near,

Answer 30

hold an accommodative target at 40 cm (16 inches)

Question 31

What can you do for kids when doing a cover-test at near?

Answer 31

Put the accommodative target on your nose

Question 32

The accommodative target for the near cover-uncover test should be

Answer 32

comparable detail/size (20/30 size)

Question 33

If there was any movement on unilateral cover test, the patient has a

Answer 33

tropia

Question 34

If you saw movement on a unilateral cover test, you must determine if the tropia is unilateral or alternating by

Answer 34

observing the movement of the uncovered eye

Question 35

What prism do you use to neutralize an exo (eye out) deviation?

Answer 35

Base In (BI)

Question 36

What prism do you use to neutralize an eso (eye in) deviation?

Answer 36

Base Out (BO)

Question 37

What prism do you use to neutralize a Hypo (eye down) deviation?

Answer 37

Base Up (BU)

Question 38

What prism do you use to neutralize a Hyper (eye up) deviation?

Answer 38

Base Down (BD)

Question 39

What prism do you use to neutralize an ortho (alignment)?

Answer 39

Verify ortho by using BI and then BD

Question 40

To assess fixation in a cover-uncover test,

Answer 40

determine if the patient is able to fixate with the right eye when the left eye is coverd, and then evaluate if the left eye is able to fixate when the right eye is covered.

Question 41

Observe any movement of the right eye as soon as the left eye is covered. If there is no movement, that means

Answer 41

the right eye was fixating when both eyes are open

Question 42

Steps to Measure the Deviation:

Answer 42

- Put prism in front of eye and watch the other - Continue to move the occluder back and forth while increasing the 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