2. DEFINITION
NORMAL BINOCULAR VISION
DEVELOPMENT OF BINOCULAR VISION
THEORIES OF BINOCULAR VISION
MECHANISM OF BINOCULAR VISION
GRADES OF BINOCULAR VISION
ABNORMALITIES OF BSV
INVESTIGATIONS
3. DEFINITION
State of simultaneous vision which is
achieved by coordinated use of both eyes so
that separate and slight dissimar images
arising in each eye appreciated as single
image by process of fusion
5. DEVELOPMENT OF BSV
BEGINS AT 4 MONTHS OF AGE
PEAKS 2 YRS
WELL DEVELOPED 4 YRS
SLOW DECLINE BY 9 YRS
6. THEORIES OF BINOCULAR
VISION
Theory of correspondence and disparity
Neurophsiological theory
Older theories
Alternation theory
Projection theory
Motor theory
Isomorphism theory
7. MECHANISM OF BINOCULAR
VISION
Visual axis
Retinal correspondence
Egocentric localisation
Horopter
Pannums fusional area
9. RETINAL CORRESPONDENCE
Normal retinal correspondence
Abnormal retinal correspondence(ARC)
Harmonius arc
Un harmonius arc
HARMONIUS angle of anamoly= angle of
strabismus
UNHARMONIUS angle of anamoly< angle of
strabismus
22. Stereopsis testing
Stereo acuity is a quantitative measure of
stereopsis, it represents the smallest horizontal
retinal image disparity that give rise to a
sensation of depth.
Stereopsis is measured in seconds of arc.
1degree=60minutes of arc, 1minute=60seconds
of arc.
Normal stereoacuity= <60seconds of arc.
23. Tests for stereopsis
Qualitative
Random dot stereograms
Synaptophore
Quantitative
Titmus fly test
TNO test
Lang test
24. MACULAR
EXTRAMACULAR
BEGINS AT 2-3 MONTHS MATURE AT BIRTH
IF DEPRIVED NEVER DEVELOPS WILL NOT DEPRIVE
POOR VN AND NYSTAGMUS --
SEVERES FIXATION ---
ONCE DEVELOPED
REINFORCEMENT REQUIRE TILL 9
YRS AGE
---
OTHERWISE AMBLYOPIA
DEVELOPS
---
CONES AND PARVOCELLULAR
GANGLION CELLS
RODS AND MAGNOCELLULAR
ANGLION CELLS
14’ OF ARC OF STEREOPSIS 200’ ARC OF STEREOPSIS
25. BV MACULAR EXTRAMACULAR
SIMULTANEOUS
PERCEPTION
NONE EXCELLENT
FUSION EXCELLENT LIMITED
STEREOPSIS EXCELLENT LIMITED
SO THERE ARE NO ADAPTATIONS IF MACULAR
BINOCULAR VISION IS IMPAIRED AND
THERE WILL BE LIMITED FUSION AND
STEREOPSIS
IF EXTRAMACULAR BV IS IMPAIRED
SUPPRESSION AND ARC TAKES PLACE
26. SUMMARY
BSV is not inborn,but develops in the first
decade of life
Abnormal visual experience results in poor or
no BSV
Reversible only if intervened in the plastic
period of development
A good understanding of mechanism of BSV
is fundamental in successive treatment of its
anamolies