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DEVELOPMENT OF VISION THE SENSORY SYSTEM AMBLYOPIA ANATOMY OF THE EXTRAOCULAR MUSCLES
Lisabeth S. Hall, M.D. Director Pediatric Ophthalmology and Strabismus New York Eye and Ear Infirmary New York NY 10003 (212) 979-4614
OKAP REVIEW OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
OUTLINE
1. Sensory physiology andpathology A. Development of normal binocular vision 1) Normal retinal correspondance 2) Vieth-Muller circle 3) Empirical horopter 4) Fusion 5) Stereopsis B. Pathology of sensory function C. Abnormal Retinal Correspondance D. Diplopia 1) Physiologic diplopia 2) Confusion E. Supression F. Monofixation syndrome G. Tests of sensory anomalies 1) Worth four dot 2) Bagolini test 3) Afterimage test 4)Synoptophore 5) Amblyoscope 6) Titmus test 2. Development of the visual system A. B. C. D. 3. Amblyopia Assessment of amblyopia Treatment of ablyopia Eccentric fixation
Anatomy of the extraocular muscles A. B. C. D. E. F. Origin Course Insertion Action Vascular supply Orbital and facial relationships 1) Lockwoods ligament
4.
Summary
OKAP REVIEW 2008
Lisabeth S. Hall, MD
Director PediatricOphthalmology and Strabismus
Pediatric Ophthalmology and Strabismus
I. Development of the visual system
OKAP REVIEW 2008
Pediatric Ophthalmology and Strabismus
II. Sensory anomalies
OKAP REVIEW 2008
Pediatric Ophthalmology and Strabismus
III. Amblyopia
OKAP REVIEW 2008
Pediatric Ophthalmology and Strabismus
IV. Anatomy of the EOM’s Summary, review and quiz
Sensory system
COLORSensory system
FORM
Sensory system
Sensory system + Motor system
LOCATION
visual space
= Sensorimotor system
visual sensations precipitate a chain of motor responses that move the eyes
1
Visual development
Vision requires:
Visual development
Vision requires: 3) synapses with feedback 4) precise binocular mapping of the environment onto the retina, lateralgeniculate body and occipital cortex
Neurophysiology Anterior visual system
stimulus received by retinal photoreceptors optic nerve optic tract optic chiasm
1) intact optical system 2) photo-pigment-mediated transformation of light into wave action potentials
Neurophysiology Lateral Geniculate Body
LGN or LGB thalamus
Neurophysiology Lateral Geniculate Body
receives afferent fibers from theanterior visual pathway relays information to primary visual cortex mechanism unknown
Neurophysiology Lateral Geniculate Body
organized in 6 layers
• 6 - outermost • 1 - innermost • uncrossed, ipsilateral - 2, 3, 5 • crossed, contralateral - 1, 4 6
Lateral Geniculate Body
important clinically must know for BOARDS:
2 cell types: • Magnacellular neurons • Parvocellular neurons
VisionNeurophysiology - LGN
Magno-large M CELLS WHERE
Neurophysiology - LGN
Parvo - small
P cells
WHAT
parafoveal, peripheral
color, two point discrimination
2
Neurophysiology Occipital lobe
Development of normal binocular vision
Objective
Visual space
also called: striate cortex Brodman’s area 17
must understand concepts of • visual space • visual direction
•objects in physical space outside of and independent of our visual system
Subjective
• conscious awareness of objects and perception by our brain
Development of normal binocular vision
stimulation of any retinal area results in visual sensation from a subjective visual direction
Retinal correspondence
Visual direction
normally fovea = visual axis = straight ahead
Normal RetinalCorrespondence
retinal areas in the two eyes share a common subjective visual direction
FL
FR
Retinal correspondence NRC
corresponding retinal points are located on the same meridian and at the same distance from the fovea in each eye
Normal Retinal Correspondence Empirical Horopter
Normal Retinal Correspondence Empirical Horopter
TL FL NL NR FR
TR TL FL NL NR FR TR
cyclopean...
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