Spatial Localisation

Assessment of Binocular Vision

Detection of Ocular Deviation

Strabismus?

Motility

Spatial Localisation

Spatial Localisation

Appreciation of spatial characteristics of environment

Judgements made relative to egocentre

Postural system relates to gravityVisual sense provides contact with

world

Spatial Localisation

Bi-dimensional localisationJudgement of direction

Tri-dimensional localisationJudgement of depth and distance

Bi-Dimensional Localisation

Position of image on the retina

Position of eye with respect to body

Visual organisation

Fovea has principle visual directionEach point on retina has a local signLocal sign is relative to fovea

Localisation

Position of image on the retina gives oculocentric localisation

Combination of oculocentric localisation and registration of eye position allows egocentric localisation

Oculocentric Localisation

Egocentric Localisation

Registration of eye position

Tri-Dimensional Localisation

Depth and distance

Monocular Cues

Motion ParallaxOver-lapping contoursRelative sizeLight and shadeAerial perspectiveGeometric perspectiveSurface texture

Over-lapping contours

Relative size

Light and shade

Aerial Perspective

Geometric perspective

Surface texture

Binocular Vision

Eyes (1982) Louise Bourgeois

Stereopsis

Binocular overlap

Binocularly coordinated eye movements

Partial decussation of afferent fibres

Common Visual Direction

Cyclopean Eye

Corresponding Points

Pairs of points on each retina share a common visual direction

A point on the nasal retina of one eye will have a corresponding point on the temporal retina of the other eye

Localised from cyclopean eyeLaw of sensory correspondence

Binocular Correspondence

Cyclopean Localisation

Physiological Diplopia

Summary

Many cues contribute to binocular perception

Binocular vision requires a highly developed visual system

Physiological diplopia is useful as a clinical tool