Foundations Of Orth And Omt: Binocular Vision And Binocular Single Vision

Front 1

What is binocular vision?

Back 1

Animals who have 2 seeing eyes

Front 2

Why do animals have binocular vision?

Back 2

- spare eye
- increase visual field
- eliminate blind spot from optic disc

Front 3

What is binocular single vision (BSV)?

Back 3

Blending of retinal images seen by each eye to form one composite image (binocularity)

Front 4

Why do we have BSV?

Back 4

- stereopsis
- summation of acuity (improved vision with both eyes open)

Front 5

What are the prerequisites for BSV? (6)

Back 5

- overlapping visual fields
- similar refractive error
- intact neuromuscular system
- retinal correspondence
- intact retinal-neural system
- partial decussation

Front 6

What is retinal correspondence?

Back 6

A relationship between the cells of the retina in each eye

Front 7

What is the retinal motor value of the fovea? What is the retinal motor value on the temporal side in the right eye? What about temporally in the left eye?

Back 7

retinal motor value @ fovea = 0
O.D. temporal = -1
O.S. temporal = +1

Front 8

What are the two theories of development of BSV?

Back 8

1. Nativism - born with genetic potential for BSV

2. Empiricism - learn BSV

* Most likely: some brain cells present at birth for BSV but BSV develops further as visual system develops (both)

Front 9

What are potential obstacles to BSV?

Back 9

1. Sensory Obstacles - Refractive obstacle of fusion
2. Motor Obstacles - absent muscles
3. CNS problems

Front 10

Define: Projection

Back 10

Mental localization of an object in space

Front 11

Temporal retina projects ________.

Back 11

Nasally

Front 12

________ retina projects temporally.

Back 12

Nasal

Front 13

What is a corresponding retinal point?

Back 13

Areas in the eyes which share a common retinal point (ex. OD +1 and OS +1)

Front 14

What is normal retinal correspondence (NRC)?

Back 14

fovea of each eye share a common direction

Front 15

What is abnormal retinal correspondence (ARC)?

Back 15

fovea of each eye no longer share a common visual direction under binocular conditions

Front 16

What is the horopter?

Back 16

location of all object points imaged on corresponding retinal areas at a given fixation distance when the central object is imaged on the center of each fovea

all objects lying on the horopter curve are seen singly (in/out create diplopia)

Front 17

What is Panum's area of BSV (Panum's Fusional space)?

Back 17

area on either side of horopter where images will still be seen singly, even with stimulation of disparate images

Front 18

What is responsible for our depth perception?

Back 18

Panum's area

Front 19

(T/F) The points falling within Panum's space are not all considered to be corresponding retinal points

Back 19

False - considered corresponding

Front 20

What is Physiologic diplopia?

Back 20

diplopia induced by objects lying in front of or behind Panum's space

(natural)

Front 21

Objects beyond Panum's space stimulate __________ retina and elicit _____________ diplopia.

Back 21

nasal
uncrossed

Front 22

Objects ________ of Panum's space stimulate temporal retina.

Back 22

in front

Front 23

relate the terms:
crossed diplopia // Panum's space

Back 23

object in fron of Panum space will stimulate temporal retina and create crossed diplopia

Front 24

What are three "grades" of physiologic diplopia?

Back 24

1. simultaneous perception - 2 images seen at same time and superimposed
2. fusion - 2 similar images blend together --> 1 image
3. stereopsis - binocular perception of depth

Front 25

What is sensory fusion? What is a prerequisite for sensory fusion?

Back 25

cortical ability to blend 2 similar images

motor fusion is prereq

Front 26

To have sensory fusion, images falling on corresponding retinal areas must be of similar: (3)

Back 26

size
brightness
sharpness

Front 27

What is the stimulus for sensory fusion?

Back 27

excitation of corresponding retinal points

Front 28

What is retinal rivalry?

Back 28

When disparate images are presented on corresponding retinal areas, fusion becomes impossible

first one image seen by one eye then other image by second -- rapid alteration

Front 29

What is motor fusion?

Back 29

measured (fusional amplitudes)

alignment of eyes so sensory fusion can be attained

Front 30

What is stereopsis?

Back 30

binocular perception of depth

Front 31

__________ keeps eyes aligned, __________ is result

Back 31

fusion
stereopsis

Front 32

What is suppression? Why do certain individuals suppress?

Back 32

mental inhibition of visual sensation from one eye

sensory adaptation; done to avoid diplopia

Front 33

(T/F) suppression resolves upon occlusion of one eye

Back 33

True - only occurs under binocular conditions & resolves with occlusion of one eye

Front 34

What are two types of suppression?

Back 34

central

peripheral

Front 35

What area does a peripheral suppression cover in an exodeviation?

Back 35

temporal to fovea

Front 36

What area does a peripheral suppression cover in an esodeviation?

Back 36

nasal to fovea

Front 37

(T/F) central suppression does not occur without peripheral

Back 37

False - to the contrary - peripheral suppression does not occur without central

Front 38

How can one measure a suppression scotoma?

Back 38

- red filter/light/prism
- W4Dot
- red filter (sbisa bar)

Front 39

What type of fusion do people with microstrabismus have?

Back 39

peripheral

Front 40

What is peripheral fusion?

Back 40

the ability to perceive two similar images on non-corresponding retinal points and still interpret them as one image

Front 41

What are some benefits of peripheral fusion?

Back 41

- allows some BSV when central area suppressed
- allows some BSV even with a visual defect
- infants - fovea underdeveloped - still have some BSV

Front 42

What are the 3 Theories of Fusion? Which one do we relate to today?

Back 42

1. Suppression Theory - one eye sees one image and other sees other image - alternate so rapidly they produce one image
2. Fusion Theory - Horopter and Panam's Fusional space
3. Mosaic Theory - parts from suppression and fusion theory

Front 43

If a patient sees 4 lights in a W4Dot test, what would you conclude?

Back 43

The patient can fuse, has some BSV

Front 44

In a W4dot test, a patient suppresses the right eye. Describe the result.

Back 44

Red filter over OD
Green filter over OS
lights on W4Dot: R, G G, W

suppression of right eye will cause patient to see 3 lights, G G and W

Front 45

In a W4Dot test, a patient has a left eye suppression. Describe the result

Back 45

Red filter over OD
Green filter over OS
lights on W4Dot: R, G G, W

Patient sees 2 lights, R & W

Front 46

Patient has uncrossed diplopia. What will he see in W4Dot test? (How many lights and where?)

Back 46

5 lights
2 red (to the right)
3 green (to the left)

Front 47

Patient has a right hypertropia. What does he see in W4Dot?

Back 47

5 lights
2 red (bottom)
3 green (top)

Front 48

Patient has a left hypertropia. What does he see in W4Dot?

Back 48

5 lights
2 red (top)
3 green (bottom)

Front 49

If a patient has crossed, oblique diplopia, what does she see in W4Dot?

Back 49

5 lights
2 red (left, top or bottom)
3 green (right, bottom or top)

Front 50

What is the Bagolini test?

Back 50

Polarized (90 degree difference)
OD: / OS: \
lenses; muscle light held as target; determine if patient has a scotoma, diplopia, micro, or BSV and fusion

Front 51

Patient has a total right eye suppression. What is Bagolini test result?

Back 51

patient sees one light with line passing through it: \

Front 52

Patient has uncrossed diplopia. Bagolini result?

Back 52

2 lights
\ /

Front 53

Patient has crossed diplopia. Bagolini result?

Back 53

2 lights
/ \

Front 54

Patient has small central suppression scotoma. Bagolini result?

Back 54

X with middle missing or light with parts of X missing

Front 55

When to use 4 pd base in/out test? How is it done?

Back 55

suspected microstrabismus

place quickly over eye - if movement seen then no suppression

Front 56

How/when is synoptophore used?

Back 56

deviation can be corrected on synoptophore
if patient has peripheral suppression, only one slide will be seen
if patient has peripheral fusion but central scotoma - fusion is possible but small details missing

Front 57

How is red glass test done?

Back 57

red filter held over fixing eye, muscle light held as a target, if patient sees one red/pink light = NRC (ARC if tropic)
2 lights = diplopia
one RED light = suppression of other eye
one WHITE light = suppression of eye with filter over it