Lecture 1

Question 1

What is binocular single vision

Answer 1

It is the ability to combine the visual information that is received by each eye to perceive a single image

Question 2

Can this image be maintained over a range of eye movements?

Answer 2

Yes

Question 3

What allows for 3D or depth perception?

Answer 3

The combination of the images from each eye which come from a slightly different angle allows for depth perception or 3D vision

Question 4

What are components of binocular vision?

Answer 4

• Simultaneous perception - Sensory fusion - Motor fusion - Stereopsis

Question 5

What is the first grade of BV?

Answer 5

Simultaneous Perception

• Simultaneously perceive two dissimilar images with each eye
• Superimpose these two dissimilar images

Question 6

What is the second grade of BV?

Answer 6

Fusion

a) Be able to superimpose two incomplete but similar images to form one complete image (Sensory Fusion)
b) True fusion is the ability to maintain fusion of similar images throughout a range of eye movements (Motor fusion)

Question 7

What is the 3rd grade of BV?

Answer 7

Stereoscopic vision

Be able to perceive depth from two slightly dissimilar images (Stereopsis)

Question 8

What are the requirements of BV?

Answer 8

1. Two forward facing eyes
2. Overlapping visual fields

Question 9

What is bifoveal fixation?

Answer 9

When fixating on an object, the fovea of each eye will receive the image

When both foveas are fixed on/ looking at an object in space, it is called bifoveal fixation

Question 10

What is cyclopean projection?

Answer 10

When an image seen straight ahead, it is seen as one (single image) - like a single eye is viewing it

Thus, an object imaged on each fovea has principle visual direction

Question 11

What are retinal correspondence?

Answer 11

Cortically linked information received by the foveas of the eye is called retinal correspondence.

Corresponding retinal points receive information from the same area in visual space. When the foveas have the same visual direction, this is called normal retinal correspondence.

Question 12

Draw a diagram illustrating Normal retinal correspondence

Answer 12

Question 13

Answer 13

Question 14

Are corresponding retinal points linked together in the brain?

Answer 14

CRP are linked together in the brain

• The image of the sun falls on the TL and NR because it is to the right of fixation
• The nasal fibres cross at the OC, which means that the information from both the TL and NR end up in the same cortical hemisphere (L)
• The signal ends in the visual cortex, where a binocular cortical cell is stimulated

Question 15

What are the requirements for BV?

Answer 15

• Overlapping visual fields allowing visual information about the objects seen to be presented to each eye simultaneously
• Retinal correspondence between eyes
• Information from one area in space going to the same part of the brain (hemi-decussation in the pathway)
• Ocular motor system which maintains fixation on the object

Question 16

What is the Horopter?

Answer 16

When each fovea is fixated on an object of regard, the image of the object will stimulate the foveal corresponding retinal points. The object will be perceived by the brain as single = sensory fusion. Other surrounding corresponding retinal points may also be stimulated by objects in visual space and alse be seen as single. The imaginary line along which these objects lie is called the horopter.

Question 17

What is Vieth-Muller circle?

Answer 17

• A circle running though the nodal points of the eye and connecting points in space that will stimulate corresponding retinal points
• Theoretically, objets that lie along the circle should be perceived as single images
• Assumes that all corresponding retinal points are equal distances apart
• this is known as the theoretical or geometrical horopter

Question 18

In reality, when the horpter is measured, is it more or less curved?

Answer 18

It is less curved and this is called the empirical horopter

Question 19

What is double vision (diplopia)?

Answer 19

It is when images are falling on non-corresponding retinal points.

Question 20

Crossed physiological diplopia

Answer 20

Question 21

Uncrossed Physiological diplopia

Answer 21