Lecture 3

Question 1

All points along the circumference of the VMO stimulates what?

Answer 1

corresponding points

Question 2

All objects located on VMO stimulate what?

Answer 2

0 binocular disparity

Question 3

The horopter is approximately ________ in near vision

Answer 3

bow-shaped

Question 4

The 3 assumption for VMO

Answer 4

Both retinas are spherical.
Both retinas have symmetric distribution of local signs across nasal and temporal retinas.
Right and left retina are the same size with the same local sign geometry.

Question 5

When we actually do an experiment on a human, we find that the locations in space that have identical monocular visual directions are what?

Answer 5

imaged onto corresponding points, are not the same as the Vieth-Müller Circle.

Question 6

The empirical longitudinal horopter is generally ______________ than the VMO.

Answer 6

less concave

Question 7

Methods of Measuring ELH

Horopter criteria:

Answer 7

1) Identical visual direction
2) Equidistance (Stereoscopic depth matching)
3) Singleness (haplopia)
4) Minimum stereoscopic threshold
5) Zero vergence

*first 2 are more commonly used methods

Question 8

When 2 targets, each presents to one eye, are perceived as lying in a single visual direction, the images of those targets must be formed on what?

Answer 8

corresponding points

Question 9

What is the only true horopter criterion (most accurate) and why?

Answer 9

Identical visual direction because it’s the only one that directly measures the visual direction.

Question 10

Nonius Horopter is aka

Answer 10

identical visual direction

Question 11

Equidistance Horopter is aka

Answer 11

steroscopic depth matching or apparent frontoparallel plane (AFPP) method

Question 12

Advantage of equidistance horopter

Answer 12

examiner can actually see the shape of the horopter directly

Question 13

disadvantage of equidistance horopter

Answer 13

AFPP method does not reflect the effects of fixation disparity, unlike the Identical visual direction

Question 14

fixation disparity

Answer 14

most people have an error so our eyes look either ahead or behind the actual target; only observed with nonius horopter

Question 15

The most popular way to measure horopter

Answer 15

Howard—Dolman Apparatus

Question 16

The Singleness (haplopia) horopter actually measures what?

Answer 16

the extent of Panum’s area at the fovea and at eccentric locations.

Question 17

The width of the zone of singleness reflects what?

Answer 17

PANUMS SPACE

Question 18

What is the most commonly used horopter?

Answer 18

equidistance

Question 19

Horopter is a collection of points which have what?

Answer 19

the exact same visual direction on each eye

Question 20

What is the most accurate horopter?

Answer 20

identical visual direction

Question 21

Why is the empirical longitudinal horopter different from the theoretical horopter?

Answer 21

all of the above? go back to check

Question 22

Two variables that affect the shape of the ELH

Answer 22

Skew (Relative magnification, R)

Curvature (Hering-Hillerbrand deviation, H)

Question 23

Regarding skew, “External” referring to being outside of the eye because?

Answer 23

we can not directly measure these angles.

Question 24

The inferred angle is influenced by

Answer 24

the optics of the eye.

Question 25

What is R?

Answer 25

the relative magnification of the retinal images between the two eyes.

Question 26

When target on the horopter, | α1=α2, R=1, will have what magnification?

Answer 26

no relative magnification

Question 27

When one eye image is magnified or minified relative to the other eye, as in aniseikonia α1≠α2, R ≠ 1, what happens to the target?

Answer 27

target no longer falls on the horopter

Question 28

How do we make α1=α2 again?

Answer 28

observer has to move the target

Question 29

review relative magnification slides

Answer 29

boo

Question 30

The horopter is skewed toward which eye?

Answer 30

magnified eye

Question 31

The perception of frontal plane is mirror image of what?

Answer 31

horopter

Question 32

The difference in curvature between the horopter and Hering- the VMO, as Hillerbrand deviation measured at the fixation point, is called

Answer 32

Hering-Hillerbrand deviation (H)

Question 33

The value of H typically ranges from what?

Answer 33

+0.1 to +0.2

Question 34

Does H indicate a flatter or steeper horopter than VMO?

Answer 34

flatter

Question 35

Why H>0 usually? Why ELH is flatter than VMO?

Answer 35

Both retinas are spherical. Both retinas have symmetric distribution of local signs across nasal and temporal retinas. —“Nasal packing” phenomenon: local sign in nasal retina are spaced closer together —Temporal visual space is overestimated Right and left retina are the same size with the same local sign geometry.

Question 36

Which visual space is overestimated?

Answer 36

temporal visual space

Question 37

What happens to the shape of horopter when we increase fixation distance?

Answer 37

curvature changes so that it goes from covex to flat than concave *however, the changes in curvature of the horopter mirror changes in curvature of the VM circle, yielding no net change in the value of H

Question 38

the viewing distance at which the apparent and objective frontal plane coincide

Answer 38

Abathic distance

Question 39

When is the horopter truly flat?

Answer 39

abathic distance

Question 40

What is the abathic distance

Answer 40

6 meters

Question 41

fixation disparity

Answer 41

misalignment of the visual axes

Question 42

binocular disparity

Answer 42

non-correspondence of the retinal regions stimulated by a target located off the horopter

Question 43

Two eyes slightly under- converge, fixation point behind the target

Answer 43

Exo Fixation Disparity

Question 44

Two eyes slightly over- converge, fixation point in front of the target

Answer 44

Eso Fixation Disparity

Question 45

a small purposeful error in vergence.

Answer 45

fixation disparity

Question 46

Factors affecting offset of ELH

Answer 46

fixation disparity | strabismus

Question 47

Strabismus affecting ELH

Answer 47

– Horopter shifts toward the intersection of the visual axis – Abnormal, seen in some strabismus – Sensory fusion is disrupted

Question 48

Fixation Disparity regarding ELH

Answer 48

normal, does not disrupt sensory fusion

Question 49

aniseikonia and horopter

Answer 49

Geometric effect Induced effect size lens

Question 50

geometric effect

Answer 50

magnification along horizontal meridian

Question 51

two eyes image size are different from each other

Answer 51

aniseikonia

Question 52

magnification along vertical meridian

Answer 52

induced effect

Question 53

special lens that only change the image size with no optical effect Meridional size lens: only change the size alone one meridion.

Answer 53

size lens

Question 54

When an axis 90 meridional magnifier is placed in front of right eye, where is the image magnified?

Answer 54

horizontally, producing retinal disparities that yield a percept of the world tilting AWAY from the right eye

Question 55

Induced effect can be measured by what?

Answer 55

the AFPP horopter apparatus (Howard-Dolman)

Question 56

Nonius horopter will not rotate because what?

Answer 56

no physical horizontal binocular disparity being created.

Question 57

what causes nonuniform magnification?

Answer 57

Prisms *More magnification at the apex than at the base

Question 58

BI prisms in front of both eyes:

Answer 58

 Temporal side more magnified than the nasal side  Horopter bends toward observer at the temporal side  Perceived world is a mirror image of the horopter  Perceived world bends away from observer

Question 59

T/F: EHL is more curved than the VMO

Answer 59

true | *when H is less than 0

Question 60

Clinical situations of curvature change where H < 0

Answer 60

* Divergence excess | * Intermittent esotropia

Question 61

3 clinical situations for irregular horopter

Answer 61

-

Question 62

Regional spatial distortion, may be a result of | anomalous retinal correspondence

Answer 62

Flom Notch