Date post: | 16-Jul-2015 |
Category: |
Health & Medicine |
Upload: | hossein-mirzaie |
View: | 3,888 times |
Download: | 4 times |
Binocular Vision
Horopter
Empirical Horopter
Panum’s Area
Panum’s Area
Physiological Basis
Requirements for Stereopsis
❚ Binocular Overlap
❚ Partial Decussation
❚ Coordinated Eye Movements
Overlapping Fields: Panoramic
Overlapping Fields: Binocular
Overlapping Fields: Binocular
Partial Decussation
Coordinated Eye Movements
❚ Gaze Holding
❚ Gaze Shifting
Retinal Function
Visual Function
Summary
❚ Object on horopter will stimulate corresponding points
❚ Objects within Panum’s region create retinal disparity and signal depth
❚ Objects beyond Panum’s region produce diplopia
Reflexes
❚ Unconditioned or innate
❚ Conditioned
Oculomotor Reflexes
❚ Postural
❚ Psycho-optical
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 acuity❚ Used to evaluate binocular development❚ Normal OKN at 4 months❚ Slow phase velocity 25 degree/sec in
newborns❚ Slow phase velocity 40 degrees/sec in
adults
OKN with BV anomalies
❚ OKN is asymmetric❚ Slow 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