Oculomotor Reflexes

Reflexes

Unconditioned or innate

Conditioned

Oculomotor Reflexes

Postural (Gaze Holding)

Psycho-optical (Gaze Shifting)

Postural reflexes

Oldest reflexes found in vertebrates

Stabilise eyes with respect to gravity

Stabilise eyes with respect to head and body movement

Vestibular System

Vestibular System

Static reflexMaintains orientation relative to gravity

Kinetic reflexStabilise with respect to head movement

VOR

Gaze-Holding

Gaze-Holding: Visual Perception

Gaze-Holding

Gaze-Holding: Visual Perception

Gaze-Holding: Visual Perception

Gaze-Shifting

Psycho-Optical Reflexes

Fixation reflexRefixation

Pursuit

Steady fixation

Fusion reflex

Development of Visual Function

Fixation Eye Movements

Refixation Movements

Development of Saccades

Pursuits: Infant

Pursuit: Naïve Adult

Optokinetic Nystagmus (OKN)

OKN

OKN

Can be used to estimate acuityUsed to evaluate binocular

developmentNormal OKN at 4 monthsSlow phase velocity 25 degree/sec in

newbornsSlow phase velocity 40 degrees/sec in

adults

OKN with BV anomalies

OKN is asymmetricSlow phase has higher velocity to

nasalward motion than temporal motion

Response seen in affected eye and normal eye

OKN remains asymmetrical in adults who have had congenital cataract or strabismus in early life

Development of Accommodation

Development of Accommodation

Development of Vergence

Accommodation and Vergence

AC/A

CA/C

Summary

Stereopsis requires binocular overlap, partial decussation and coordinated eye movements

Eye movements have various components

Development of eye movements rapid

Vergence high order control