Introduction To Binocular Vision

Sight

Ability of the eyes to detect light/to see.

Vision

Brain’s interpretation of that visual information.

Vision

Brain’s interpretation of that visual information.

1. Proper Fixation with each eye.

2. Reflex Activities which produce fusional movements must be present.

3. Image formed on each retina must be approximately similar.

4. Visual Fields of the two eyes must overlap to a large extent.

5. Common visual direction must be there of two eyes.

Prerequisite of Binocular Vision? (5)

• Sensory Mechanism

• Motor Mechanism

• Central Mechanism

Mechanisms of Binocular Vision? (3)

Single Mental Impression

The brain combines the two slightly different images received from the right and left eyes into one unified image.

Sensory Mechanism

The process of single mental impression is called?

Sensory Mechanism

It is concerned especially with visual apparatus and proprioreceptive receptors of extrinsic ocular muscles.

Motor Mechanism

Concerned essentially with the maintenance of two eyes in a correct positional relationship at rest and in motion.

Central Mechanism

It is concerned with act of fusion (sensory) and cortical control of ocular movement (motor).

• Anatomical Factorra

• Physiological Factors

Types of Motor Mechanism? (2)

• Postural Reflex

• Fixation Reflex

• Kinetic Reflex

Physiological Factors of Motor Mechanism?

Postural Reflex

Responsible for the subconscious maintenance of the body’s posture when movement and position is altered and they ensure that the body remains upright and aligned.

Postural Reflex

It is the effects of gravity on the body which triggers their response and so these reflexes do not begin to develop until after the baby is born.

• Midbrain

• Born

Postural reflexes are found in the _____ and do not begin to develop until after the baby is _____.

• Static Postural Reflex

• Stato-Kinetic Reflex

Two types of Postural Reflexes?

Static Postural Reflex

Changes in the position of head relative to body.

Static Postural Reflex

Doll head phenomenon

Stato-Kinetic Reflex

Changes in the position of head relative to space, in response to movements of acceleration and deceleration,

Semi-circular canals

Stato-Kinetic Reflex is controlled by the?

• Part of the labyrinth:

  • Utricle

  • Saccule

  • Proprioreceptive impulse from neck muscles.

Static Postural Reflex is controlled by part of the?

Fixation Reflex (Psycho-Optical)

Maintenance of two eyes in their correct positions within the orbits so that the visual axes are aligned correctly with one another despite changes in movement of the head relative to the body or of the body relative to space as a result of visual stimuli which reach the visual cortex by the afferent visual pathway.

Fixation Reflex

Psycho-Optical is also known as?

Fixation Reflex

Conditioned reflex

Postural Reflex

They are entirely unconditioned reflexes.

Fixation Reflex

Ability of each eye to fix a definite object.

Afferent Visual Stimuli

Fixation Reflex is initiated with?

• Passive Re-Fixation

• Active Re-Fixation

2 Types of Refixation Reflex?

Passive Re-Fixation

Ability of the eye to retain fixation of a moving target.

Active Re-Fixation

Change fixation from one object to another object.

Conjugate-Fixation Reflex

Application of fixation reflexes to both eyes at the same time so that they retain fixation during the conduct of conjugate movements.

Disjunctive or Vergence Fixation Reflex

Application of fixation reflex to both eyes at the same time so that the eyes retain fixation movements during the conduct of a disjunctive movement.