2. Outline
Theory of Binocular Vision
Stereopsis and Sensory Adaptations
Extraocular Muscles
Examples of Common Motility Problems
3. Outcomes
• State the advantages of upright position
• Discuss the 2 theories of development of binocular
vision
• Differentiate diplopia from visual confusion
• Define sensory adaptations of an immature visual
system
• Define Worth’s 3 levels of fusion
• Discuss amblyopia, its definition, types, diagnosis and
management
• Differentiate horror fusionis from central fusional
disruption
• Enumerate the EOMS, its origin, insertion, action
• Define and apply laws of ocular motility
• Identify some of the more common motility problems
10. • visual stimuli from retina to
visual cortex modified and coded
• Macaque monkey: Ar 18;
Rhesus: Ar 17-18
• only 25% binocularly driven cells
are stimulated equally; 75%
graded influence from R & L eye
• Lost binocular neurons do not
recover
Neurophysiologic
Theory
11. NORMAL Figure from Wright’s Pediatric Ophthalmology
Lateral Geniculate Nucleus
in Strabismic Amblyopia
11
12. Macula Development
Fine visual discrimination
characteristic of high visual
acuity requires sharply
focused small objects as
appropriate stimuli
12
http://www.macuhealth.com
15. Worth’s level of fusion
• First degree (simultaneous
perception)
• Dissimilar targets presented
• Perceived at the same time in the
same visual direction
• Second degree
• Third degree
15
16. Worth’s level of fusion
• First degree (simultaneous
perception)
• Second degree (flat fusion)
• similar targets with dissimilar
components (monocular
suppression checks)
• Third degree
16
17. Worth’s level of fusion
• First degree (simultaneous
perception)
• Second degree (flat fusion)
• Third degree (stereopsis)
• Same targets as 2nd degree +
disparity
17
18. Diplopia vs Visual Confusion
18
From Rosenbaum & Santiago Clinical Strabismus Management 1999
19. Suppression
alteration of visual sensation
that results in inhibition or
prevention of one eye’s
image from reaching
consciousness
19
https://i.ytimg.com/vi/wb2IvkBrlJc/maxresdefault.jpg
21. Amblyopia Definition
Unilateral or bilateral decrease in VA
caused by pattern vision deprivation (lack of adequate
vision stimulation) or abnormal binocular interaction
physical examination shows no anatomical abnormality
reversible by therapeutic measures
21
http://www.ascrs.org
vonNoorden GK. Amblyopia. A Multidisciplinary Approach. Proctor Lecture. IOVS; 1985; 26: 1704-16
Gunter K von Noorden
24. Classification
of amblyopia
24
Reversible (functional)
Strabismic amblyopia
Anisometropic / ametropic
amblyopia
Visual deprivation amblyopia
Idiopathic amblyopia
Toxic / Nutritional amblyopia
Irreversible (organic)
Amblyopia in nystagmus
Other ocular pathologies
25. Amblyopia vs
Suppression
• Both occur to eliminate visual confusion from
dissimilar retinal images
• Suppression occurs only under binocular
conditions
• Amblyopia persists after closure of fixating eye
25
30. Horror fusionis
• “fear of fusion”
• Unable to simultaneously
perceive images presented to
either eye in the same place in
space
• Seen in patients with childhood
strabismus and harmonious ARC
30
From Rosenbaum & Santiago Clinical Strabismus Management, 1999
31. Central fusion disruption
• History of closed head trauma
• Diplopia persists even if images
fall on fovea of both eyes
• Requires haploscope or
amblyoscope for diagnosis
• Images swim around each other
31
38. Motility
terms
Agonist muscle:
muscle that causes a
movement
Antagonist muscle:
muscles that inhibit
the movement of the
agonist
Yoke muscles: muscles
in either eye that work
together in specific
directions of gaze
Synergistic muscles:
muscles that move the
eyes in the same
direction as the
agonist.
39. Motility Terms
Ductions: movement of one
eye
Versions: movement
of both eyes in the
same direction
Dextroversion,
Levoversion,
Supraduction
Infraduction
Vergence movements:
movement of both
eyes in opposite
directions
Convergence
Divergence
42. Laws of
Ocular
Motility
Hering’s Law of
Equal Innervation
Yoke muscles receive equal
innervation
Sherrington’s Law
of Reciprocal
Inhibition
Increased innervation to an
agonist muscle is
accompanied by reduced
innervation to its antagonist
muscle