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