1 Intro to BV

What information does Monocular vision provide?

• Provides info to identify & recognize objects- the “what” part

• Provides info about visual direction, motion and depth perception-the “where” part

• Depth cues

Give examples of Depth cues.

• Linear perspective

• Ccclusion

• Elevation

• Texture gradients

• Motion parallax

What information does Binocular vision provide?

• Binocular Summation

• greatest contribution in our perception of “where” objects are located

• enhances our perception of:

  1. Visual Direction

  2. Depth Perception

Define Binocular Summation.

→ additivity of info from two eyes to yield binocular visual performance

• significantly enhances the “what” and the “where” part (of objects) to yield binocular visual performance

• vsion is sharper with 2 eyes, shower lower thresholds than with 1 eye alone

List everything thats enhanced by Binocular Summation.

• Light detection thresholds

• Visual Acuity

• Contrast sensitivity

• Visual field

• Color Vision, Hand-eye coordination, Depth and Motion perception

• Greater sensitivity makes things which are smaller, dimmer, quicker etc more detectable

Why is the study of BV important to Optometry? List 5 reasons.

• Managing patients with complaints of eyestrain, headaches, difficulty reading convergence insufficiency, strabismus etc.

• Visual Development and Pediatric Vision/Optometry

• Vision Therapy

• Monovision (CL)

• Driving

List the 5 major advantages of having 2 eyes.

1) Spare Eye

2) Wider FOV (Major Benefit)

3) Binocular Summation

4) Stereopsis (Major Benefit)

5) Other Enhancements to visual performance

What is the monocular VF without eye movements?

150^o

What is the binocular VF without eye movements?

180^o

What is the central overlap VF?

120^o

What is the VF superiorly, inferiorly, nasally and temporally?

Nasal = 60^o

Inferior = 70^o

Temporal = 100⁰

Superior = 60^o

Define Temporal Crescents.

crescent-shaped monocular VF (seen by one eye alone) lateral to the binocular field

What determines the total visual field and binocular overlap?

→ position of the eyes in the head, specifically the intraocular distance (~60–65 mm), determines:

• Total width of the VF using both eyes

• Width of the overlapped binocular visual field

What is Stereopsis?

→ highly accurate means of determining the position of objects around us in relationship to our position, and to determine our position relative to our environment

• e.g., helps for grasping near objects and driving

• accurate sense of depth perception that’s unique to binocular vision

• most significant advantage gained by binocular vision

What is the most significant advantage gained by binocular vision?

Stereopsis

How can compromised binocular vision (BV) affect elderly drivers?

Elderly drivers with compromised BV but normal VA have been reported to have higher-than-average accident rates

How can correcting strabismus affect children’s visual-motor skills?

Correcting strabismus → restores/allows BV → improves visual-motor skills, especially hand-eye coordination

List the disadvantages of having 2 eyes.

• More complex neurophysiology → brain must coordinate and fuse input from 2 eyes

• Poor coordination between the eyes can cause BVdisorders

  • Sx: eyestrain, HA, and difficulty reading

• Even slight misalignment can cause diplopia

List 4 factors that cause binocular stress.

1. Incorrect refractive balance

2. Dissimilar images between the two eyes due to aniseikonia

3. Convergence insufficiency or convergence excess

4. Conflicts between accommodation and convergence

List 4 things that misalignment between the two eyes incorrectly can produce.

1. Strabismus

2. Amblyopia

3. Diplopia

4. Suppression

In severe/intractable diplopia, how can a binocular vision problem be treated?

Occlude (patch) one eye → interrupts BV → makes the patient monocular → eliminates diplopia

True or False: Depth perception is only possible with binocular vision.

False, depth perception can occur monocularly such as:

• Relative size

• Linear perspective

• Interposition/occlusion

• Motion parallax

How much does stereopsis contribute to judging depth for far objects?

Very little beyond a few meters

• e.g., far objects (e.g., piloting/landing an airplane or driving), depth perception relies mainly on monocular depth cues, not stereopsis

List the requirements for Binocular Vision.

1. Two eyes - separated intraocularly –about 65 mm in adults

2. Neural pathway- to transfer visual information to the brain

3. Neural processing system - to integrate & analyze raw visual info (size, luminance, color, contrast, movement relative to the eye etc.)

4. EOM -to allow the fixated objects to be imaged in the

5. retina

6. Motor control systems- to govern voluntary and reflex eye movements

7. Head and body movements + monocular cues to the total perception

Describe the VF in a frog 🐸.

• Almost 360^o

• Panoramic Vision

• Little or no overlap of VF

True or False - Individuals with BV issues is uncommon.

Patients with BV problems represent a large % of patients