Lecture 1

Question 1

Why do we need 2 eyes?

Answer 1

1. spare eye
2. larger field of view
3. better visual function due to binocular summation

Question 2

Monocular Field of human

Answer 2

145 degrees

Question 3

Total Visual Field of human

Answer 3

180+ degrees

Question 4

Binocular Visual Field of human

Answer 4

130+ degrees

Question 5

How does stereopsis arise?

Answer 5

subtle difference b/w images in each eye

Question 6

What is the real advantage of binocularity?

Answer 6

highly accurate depth perception

Question 7

Clinical binocular problems

Answer 7

1. failure to align two eyes

2. two eyes aligned, but system is stressed

Question 8

Fail to align two eyes:

Answer 8

Strabismus, amblyopia,

diplopia, suppression etc.

Question 9

two eyes aligned, but system is stressed:

Answer 9

-Incorrect refractive balance

Question 10

Misconception about binocular vision

Question 11

The ‘real world’. The 3-D space

around us and all the objects located in it

Answer 11

Physical Space aka object space

Question 12

Your perception of the physical space in relation to you. It is a construct of the brain.

Answer 12

Visual Space

Question 13

A goal of vision

Answer 13

is to construct a visual space that looks like the physical space.

Question 14

What happens when visual space does not match the physical space?

Answer 14

-Optical illusion - normal

Question 15

Visual Direction under monocular condition

Answer 15

oculocentric

Question 16

Oculocentric direction

Answer 16

is visual direction relative to where the eye is fixating.

Question 17

Principal Visual Direction (PVD)

Answer 17

the reference direction, where fovea is fixating

Question 18

How is visual direction (oculocentric direction) under monocular condition measured?

Answer 18

angle between PVD and the SVD

Question 19

If SVD is to the right of PVD what is alpha?

Answer 19

positive

Question 20

if SVD is to the left of PVD what is alpha?

Answer 20

negative

Question 21

What is the direction signaled by fovea?

Answer 21

PVD

Question 22

What is the oculocentric sense of “straight ahead”?

Answer 22

PVD

Question 23

What is zero direction?

Answer 23

PVD

Question 24

Does oculocentric direction move with the eye?

Answer 24

yes! b/c PVD changes when your eye moves

Question 25

a unique oculocentric direction associated with a specific retinal point.

Answer 25

local sign

Question 26

how is the local sign determined?

Answer 26

the retinotopic mapping of the retinal locus in LGN and cortex

Question 27

what does mechanical visual phosphene show?

Answer 27

the neural basis of local sign

Question 28

what does local sign size relate to?

Answer 28

retinal eccentricity

Question 29

what is the basis for local sign size?

Answer 29

directional discrimination

Question 30

how is local sign mostly determined?

Answer 30

the BRAIN

Question 31

how big are foveal local signs?

Answer 31

1/7 the size of foveal cone

Question 32

what is the basis for hyperacuity?

Answer 32

local sign size

Question 33

How big are peripheral local signs compared to peripheral cones?

Answer 33

much larger

Question 34

what type of acuity determines what the object is?

Answer 34

resolution acuity

Question 35

in the demonstration, with the same amount of offset b/w the two lines, why can you resolve the line offset in central vision, but cannot do so in peripheral vision>

Answer 35

local sign size is larger in peripheral retina compared to fovea

Question 36

what type of acuity determines where the object is?

Answer 36

hyperacuity

Question 37

a perception of object shape that differs from its true shape

Answer 37

metamorphopsia

Question 38

Cause of metamorphopsia

Answer 38

– Neuroanatomical:
• Retinal disease—most common and most evident
• Stabismus and amblyopia– very subtle, pt might not be aware of it
– Optical: extreme corneal distortion Example: keratoconus

Question 39

What do retinal diseases cause regarding metamorphopsia?

Answer 39

displacement of the local signs leads to spatial distortion

Question 40

different image positions withina local sign region will have the same ____________?

Answer 40

visual direction

Question 41

PVD become associated with the local sign of peripheral retina other than fovea

Answer 41

eccentric fixation (EF)

Question 42

EF can be found in:

Question 43

In eccentric viewing (EV) what is the PVD associated with?

Answer 43

fovea

Question 44

Regarding EV, is the patient aware of using peripheral vision to see?

Answer 44

yes

Question 45

Where can EV be found in?

Answer 45

short term macular disease

Question 46

In low vision rehab, what is the patient trained to use?

Answer 46

EV

Question 47

visual direction under binocular condition

Answer 47

egocentric direction

Question 48

The binocular sense of visual direction uses a point in the head called

Answer 48

egocenter (reference point)

Question 49

represents a single hypothetical eye located approximately midway between the two eyes.

Answer 49

cyclopean eye

Question 50

why does the hole in hand demonstration work?

Answer 50

oculocentric for left eye: 0
oculocentric for right eye: 0

when both eyes open, brain will unify them with egocentric angle of 0, which is our binocular view and u will see hole in hand.

Question 51

The brain receives input from the two eyes, and computes the egocentric direction of an object based on two sets of data:

Answer 51

1) The retinal location of the object’s image in each eye (oculocentric direction)
2) Each eye’s orientation, or direction of gaze.
The brain receives direction of gaze information, possibly from proprioception within the extraocular muscles and/or from the oculomotor neurons that drive the muscles.