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OKAP REVIEW OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS April 1. 2008

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...