Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Vision Science 5 > Lecture 5 > Flashcards

Lecture 5 Flashcards

(56 cards)

Start Studying
1
Q

Does fixation disparity affect the horopter property?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which horopter criterion belongs to fixation disparity?

A

identical visual direction horopter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The vergence angle of the eye, the angle between the visual axis, is slightly inaccurate
The fixation point does not coincide with the actual target in space.
“Fixation disparity should not be confused with binocular disparity: fixation disparity is a misalignment of the visual axes; binocular disparity is non-correspondence of the retinal regions stimulated by a target located
off the horopter.”

A

fixation disparity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When a subject has exo fixation disparity, what type of binocular disparity does the intended fixation target have?

A

crossed binocular disparity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what type of vergence does crossed binocular disparity stimulate?

A

CONVERGENCE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What type of binocular disparity does an eso FD cause?

A

uncrossed binocular disparity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of vergence does uncrossed binocular disparity cause?

A

divergence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

________ is a small purposeful error in vergence

A

fixation disparity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

FD and heterophoria is USUALLY correlated or uncorrelated?

A

correlated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

exophoria pt usually has what type of FD?

A

exo FD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

esophoria pt usually has what type of FD?

A

eso FD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

FD and heterophoria always agrees. T/F

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

FD: test under binocular condition - what type of phoria?

A

associated phoria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

heterophoria: test under monocular condition – what type of phoria?

A

dissociated

ex: cover test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The amount of prism needed to eliminate fixation disparity.

A

associated phoria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

horizontal associated phoria is usually smaller than what?

A

horizontal dissociated phoria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

associated phoria is a more reliable indicator for what?

A

successful prism prescription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

seen by both eyes, has an angular

width of 1.5

A

binocular fusion lock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

seen monocularly OD sees top line, OS sees bottom line

A

Two Nonius lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Clinical measurement of FD

A

 Binocular fusion lock

 Two Nonius lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

most accurate way of measuring FD

A

sheedy disparometer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what uses the same method of sheedy disparomter?

A

saladin card

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Wesson Card testing principle

Study These Flashcards
A

 The polarized lines on the Wesson card are actually centered.
 The lines mark the intended fixation point but each eye’s visual
axis misses it.
 They appear deviated due to the fixation disparity.

24
Q

if pt has exo FD, what happens with wesson card test?

Study These Flashcards
A

top eye image compared to bottom, is more towards left side

25
wesson card: if arrow points to the right what type of FD?
exo FD
26
wesson card: if arrow points to the left what type of FD?
eso FD
27
sheedy: if bottom is to the left what type of FD?
exo FD
28
sheedy: if bottom is to the right, what type of FD?
eso FD
29
The sheedy disparometer marks the location of what?
visual axes of each eye; what doctor sees
30
the wesson card shows what?
perceived location of the fixation point relative to each visual axis; what patient sees
31
– The amount of prism needed to eliminate | fixation disparity
associated phoria
32
how is prism use with associated phoria?
used to shift the images to match the visual axis
33
Binocular rivalry can occur when very different images of exactly equal salience fall on corresponding points. T/F
False
34
Wesson Card: bottom arrow points to the right side. Half way towards the first point. How do you record FD?
4.3 min of arc exo FD
35
Saladin card: bottom vertical line is to the right. | How do you record FD?
Eso FD
36
If BI prism is placed on two eyes, what type of disparity is created?
Uncrossed binocular disparity stimulates negative fusional vergence Eyes diverge to maintain bifoveal fixation
37
uncrossed binocular disparity pt on sheedy test will see what?
top to the right
38
BO prism stimulates what type of vergence?
positive fusional vergence (convergence)
39
If we increase BI prism, what will happen to FD?
FD decreases
40
What if we put too much BI prism?
visual axis no longer moves, but images move farther temporally outside of visual axis --> FD increases towards eso (oppositely)
41
What axis for FVFD curve: amount of prism used to stimulate the vergence system
X axis
42
What axis for FVFD curve: fixation disparity, how closely the visual axis keeps up with the stimulus
Y axis
43
Y intercept on FVFD curve represents what?
FD (no prism)
44
X intercept on FVFD curve represents what?
associated phoria (FD=0)
45
Once we go beyond Panum's fusional area, what will the patient experience?
diplopia
46
A greater slope across the middle section would show
that fixation disparity is slowly changing with the addition of prism.
47
When prisms stimulate vergence eye movements, the eyes tend to lag behind the prism, causing
a gradual change in the amount of fixation disparity. This is reflected in the slope.
48
The flatter the slope, the better the eyes are able to maintain what?
their starting level of fixation disparity (better vergence adaptation).
49
flatter and wider slope represents
a better system
50
What type is most common and considered a normal response?
Type I
51
eso FD when no prism, add BI increase the eso FD; add BO decrease eso FD till it becomes 0, then become exo FD.
Type I eso
52
exo FD when no prism, add BI decrease exo FD till it becomes 0, then become eso FD; add BO increase the exo FD.
Type I exo
53
What type curve is usually found in pt with large eso phoria?
Type II
54
What type of patient will respond to prism correction well?
eso heterophoria pt
55
What type of curve is usually found in pt with large exo phoria?
Type III
56
What type of curve for patient that has a small exo FD.
type 4

Vision Science 5 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions