Heterophoria

Question 1

Normal Binocular vision:

Answer 1

Both eyes simultaneously cooperating with their bifoveal fixation to give a single perception of the object

Question 2

Sensory fusion of binocular vision

Answer 2

Integration of similar images at the cortex

Question 3

Motor fusion of binocular vision

Answer 3

Motor alignment to sustain binocular vision

Question 4

Motor fusion tries to ________ ___________ of the two images and _____ ___________ to produce one image.

Answer 4

Eliminate disparities, needs vergences

Question 5

NPC is:

Answer 5

The closest distance where the eyes can converge and maintain binocular vision

Question 6

Two types of cover tests

Answer 6

Cover-uncover test

Alternating cover test

Question 7

Cover-Uncover test

Answer 7

Presence of a deviation (Phoria or tropia)
Lateral its/which eye (unilateral or alternating)
Frequency of the deviation (constant or intermittent)

Question 8

Alternating cover test

Answer 8

Direction of the Phoria and tropia

Magnitude (size) of the deviation

Question 9

Which cover test is done first?

Answer 9

Cover-uncover

Question 10

Are cover test done at distance or near?

Answer 10

Both

Question 11

On cover-uncover, will you see phoria or tropia?

Answer 11

Tropia

Question 12

On alternating cover test, will you see phoria or tropia?

Answer 12

Phoria

Because fusion is broken

Question 13

What does alternating tropia mean?

Answer 13

Either eye can fixate on the target.

Question 14

What is heterophoria?

Answer 14

Aka Phoria

A tendency of the eyes to deviate when fusion is blocked.

When there is binocular vision and fusion on a target, both eyes are aligned on the target.

..When there is something to focus on, there is no tendency to deviate..

Question 15

The visual axes of both eyes intersecting and fixating on a target created what?

Answer 15

Fusion, binocular single vision

Question 16

Visual axes extend from..

Answer 16

The fovea to the point of fixation

Question 17

Even though Phoria occurs when fusion is broken, there can still be ____________

Answer 17

Abnormalities in the binocular vision

Question 18

Symptoms associated with a heterophoria could occur if _________________________

Answer 18

Fusion all amplitudes are not enough

Question 19

Heterophoric abnormalities

Answer 19

Convergence insufficiency
Convergence excess
Divergence insufficiency
Divergence excess

Question 20

Phorias and tropias must be measured at:

Answer 20

Distance and near

Question 21

How can phorias be measured and identified?

Answer 21

During cover test or with a Maddox rod

Question 22

Maddox rods are used to measure what?

Answer 22

Horizontal and vertical Phoria at distance and near

Question 23

What does the Maddox rod do?

Answer 23

Dissociates the eyes

Question 24

What items are needed to test Maddox Rod Phoria?

Answer 24

Penlight

Handheld Maddox rod

Prisms

Question 25

At what distance must near testing for Maddox rod Phoria be done?

Answer 25

40 cm

Question 26

For horizontal Phoria, the Maddox rods’ grooves are oriented:

Answer 26

Horizontally

To give a vertical streak

Question 27

For vertical Phoria, the Maddox rods’ grooves are oriented:

Answer 27

Vertically

To give a horizontal streak

Question 28

During Maddox rod Phoria, patient must look at:

Answer 28

The white light and be aware of the red streak

Question 29

If the red line is thought the white light,

Answer 29

Ortho

Question 30

If the red line is to the right of the light,

Answer 30

Uncrossed diplopia, eso

Question 31

If the red line is to the left of the light,

Answer 31

Crossed diplopia, exo

Question 32

If the red line appears below the light,

Answer 32

Right hyper

Question 33

If the red line is above the light,

Answer 33

Left hyper

Question 34

The pt must hold the Maddox rod over what eye?

Answer 34

Right eye

Question 35

Uncrossed diplopia is ___ deviation because:

Answer 35

Eso, because the eye is deviated in, the light hits the nasal retina and projects temporally

Question 36

Crossed diplopia is ____ deviation, because:

Answer 36

Exo, because the eye is deviated out.

Light hits the temporal retina and projects nasally, across and beyond the visual axis of the fixating eye.

Question 37

What is suppression?

Answer 37

The active deactivation of a retinal image in one eye by the visual cortex

Question 38

The brain prefers to suppress (shut off imaging in an eye) to do what:

Answer 38

Provide vision as close to binocular vision as possible instead of:
Any image disparity
Blurred vision
Diplopia
Confusion

Question 39

What is alternate suppression?

Answer 39

Alternating which eye is being suppressed,
For ex,
See 2 dots then 3 dots during W4Dot

Question 40

How do you measure the size of the Phoria?

Answer 40

With a prism bar

Question 41

If exo,

Answer 41

Use BI

Question 42

If eso,

Answer 42

Use BO

Question 43

For R hyper,

Answer 43

Use BU over OS 9since Maddox Rod is over OD)

Question 44

For L hyper,

Answer 44

Use base down over OS

Question 45

What is modified thorington Phoria?

Answer 45

Same as Maddox Rod Phoria, but thorington cards are used for distance and near.

Penlight is held through the middle of the card, and pt describes where the red line is

Question 46

What is angle lambda?

Answer 46

The angle between the corneal reflex and the center of the pupil

Hirschberg

Question 47

3 possible corneal reflex positions (Hirschberg)

Answer 47

Center of the pupil

Nasal to the pupil (positive angle lambda)

temporal to the pupil (negative angle lambda)

Question 48

1 mm of estimated deviation from the relative point =

Answer 48

Approximately a deviation of 22 prism diopters