Transcript Slide 1 - sccoer.net

Binocular Vision and
Space Perception
Eric Borsting, OD, MS
Professor
Dr. B
Graduate from SUNY in 1987
 Residency in Peds/VT
 Staff in VT
 Teaching at SCCO for over 20 years
 Teaching this course for 3 years
 Live in Brea with my wife and 2 kids

Overview
Ground rules
 Lecture and lab schedule
 No labs week of January 3
 Outside of class work

 Quizzes,
presentations, self-study material
Ground Rules
Office Hours C126
 Attendance
 Grading
 Textbook

Testing
Mainly multiple choice
 Study guide questions
 No surprises
 Problem Sets
 Quizzes

Moodle
Assignments
 Quizzes
 Calendar
 Grades

Lab
Bring trial lens set to all labs
 Demonstrate principles taught in lecture
 Presentation
 C113

Why is this important?
The visual system helps us orient and
move through space.
 The visual system provides the most
precise information about our position and
the position of objects in the environment.

Two systems used for perceiving
space

Monocular
 Several
cues
 Occlusion

Binocular
 Stereopsis
Why is this important?
The visual system is highly adaptable.
This course will look at the ability to adapt
to lenses and prism that alter space
perception.
 The visual system will adapt to
developmental or acquired anomalies that
affect binocular vision or space perception.
Clinical applications
Strabismus
 Amblyopia
 Aniseikonia
 Unilateral visual neglect

Clinical applications
Monovision
 Correcting anisometropia
 Correcting astigmatism
 Occlusion therapy
 Bifocal correction

One Eyed Optometry

This is what we do most of the time
Two-Eyed Optometry

Binocularity makes us look at one eyes
condition relative to the other eye.
Problems
Why do we need two eyes?

Advantages of two eyes
 Stereopsis
 Insurance
policy
 Wider visual field for binocular viewing
 Spatial vision
Why do we need two eyes?

Disadvantages of two eyes
 Prevalence
of binocular problems quite high
Why do we need two eyes?

Linkage of the two eyes
 Very
precise compared to other systems
 Hands versus eyes
Evolutionary Aspects
Parameter
Species
Binocular
Field
Vergence Eye
Movement
Decussation
Lateral Eye
Placement
Lower
Frontal Eye
Placement
Higher
Very little
A lot
Poorly
developed
Highly linked
Total
Partial
Why do we need two eyes?

Correspondence
 Examples
Defining Visual Space

Objective visual space

Infinite boundaries
 Objects move without being
deformed
 Can measure very precisely
Defining Visual Space

Image Space

The image of space at the retina
Defining Visual Space

Subjective visual space (perceived,
phenomenal, or experiential spaces)

The space of perceived things
 Finite boundaries
 Objects can be distorted
Defining Visual Space

Subjective visual space

Body (personal) space
 Reaching (peripersonal) space
 Far (extrapersonal) space
Monocular or Oculocentric Visual
Direction
Local sign: Each neuron encodes a unique
visual direction
 Principle visual direction: The direction
signaled by the fovea
 Secondary visual direction: All directions
other than the principle direction

Clinical application
Eccentric Fixation
 Occurs when the principle visual direction
is different from the fovea. This can occur
in strabismic amblyopia.

 Objective

visual direction
Visuoscopy
 Subjective
visual direction
Clinical application

Eccentric viewing: Patient uses a point
other than the fovea when looking straight
ahead secondary to vision loss at the
fovea. Commonly seen in macular
degeneration.
Demonstration
Use ophthalmoscopes to find the fovea
 Look at the center of the target
 Now look off to the side

Subjective Visual Direction
The perception of looking straight ahead
 Eccentric viewing
 Eccentric fixation

 The
principle visual direction has shifted away
from the fovea.
How do we combine two different
views of the world?

Two separate principle visual directions

Correspondence problem
Law of identical visual direction

Objects lying in the same visual direction
in each eye will be seen as lying in a
single visual direction under binocular
viewing conditions. The foveas indicate
the same principle visual direction
How do put the two eyes together?
Hering window experiment
 Hole in your hand
 Sausage

Egocentric localization

Objects from striking each fovea are
perceived to fall on a single point midway
between the two eyes. This has been
called the cyclopean eye.
Dominant Eye
Common methods used to determine
 Effect on egocentric localization
 Most individuals egocentric point is shifted
towards the dominant eye.

Corresponding retinal points

These are pairs of points one in each that
when stimulated simultaneously give rise
to a common visual direction.
Vieth Muller Circle

This is a geometric representation of the
corresponding points in each eye. It is
formed by drawing a circle through the
fixation point and the entrance pupil of
each eye.
Binocular disparity
What happens to objects not lying on the
Vieth-Muller circle?
 The difference in visual direction between
the two eyes. This occurs when noncorresponding points are stimulated.

Binocular Disparity
Horizontal disparity gives rise to stereopsis
or the perception of depth.
 Vertical disparity does not give rise to
depth perception.

Binocular Disparity
Crossed disparity
 Uncrossed disparity

Panum’s Area

Allows for small disparities to give rise to
depth perception within and single vision
within a certain range.
Diplopia
Physiological diplopia occurs when images
are outside of Panum’s areas and are on
non-corresponding points.
 Crossed and uncrossed diplopia
 Examples

Pathological Diplopia
Diplopia of a fixated target
 Occurs in strabismus with minimal
suppression.
 Esotropia it is uncrossed
 Exotropia it is crossed

Confusion
Binocular confusion occurs when two
different objects are seen in one direction
or location.
 Examples
