2. Introduction
• Under normal conditions, the image of the
object of regard falls simultaneously on the
fovea of each eye, when the eyes are in
perfect alignment. Any deviation from
perfect ocular alignment is known as
“STRABISMUS.”
6. DUCTION
• Monocular rotations with no consideration
of the position of the other eye
– Adduction : Inward rotation
– Abduction : Outward rotation
– Elevation or Supraduction : Upward rotation
– Depression or Infraduction : Downward
rotation
7. FUSION
• Formation of one image from the two
images seen simultaneously by the two eyes
– Motor fusion (EOM control)
– Sensory fusion (visual sensory integration of
the brain)
8. HETEROPHORIA
• Latent deviation of the eyes held straight by
binocular vision
– Esophoria : tendency to turn inward
– Exophoria : tendency to turn outward
– Hyperphoria : tendency to deviate upward
– Hypophoria : tendency to deviate downward
9. Heterotropia/Strabismus
• Manifest deviation of the eyes that can not
be controlled by binocular vision
– Esotropia : convergent manifest deviation
– Exotropia : divergent manifest deviation
– Hypertropia : manifest deviation of one eye
upward
– Hypotopia : manifest deviation of one eye
downward
10. Definition of Other Terms
• Orthophoria : absence of any tendency of
either eye to deviate when fusion is
suspended
• Primary deviation : deviation measured
with the normal eye fixating and the eye
with the paretic muscle deviating
• Secondary deviation : deviation measured
with the paretic eye fixing and the normal
eye deviating
11. Definition of Terms
• Prism Diopter - a unit of angular
measurement used to characterize ocular
deviations
• Torsion : rotation of the eye about its
anteroposterior axis
– Intorsion : 12 o clock meridian turning toward
the midline
– Extorsion : 12 o clock meridian turning away
from the midline
12. Definition of Terms
• Conjugate Movement : Movement of the
two eyes in the same direction at the same
time
• Vergences : Movement of two eyes in
opposite directions
– Convergence : The eyes turn inwards
– Divergence : The eyes turn outwards
13. Synergistic and Antagonistic
EOMS
• Sherrington’s Law - There is a reciprocal
innervation of antagonistic muscles.
– The antagonist relaxes as the agonist contracts
• eg. The right eye’s right gaze would involve a
contraction of the right lateral rectus and a
relaxation of the right medial rectus
14. YOKE MUSCLES
• Hering’s Law : for movements of both eyes
in the same direction, the corresponding
agonist muscles receive equal innervation
– e.g. When gazing right the right lateral rectus
contracts along with the left medial rectus
15. Definition
• Concomitant Strabismus : the degree of
deviation is equal in all fields of gaze
• Incomitant (paretic) Strabismus : the degree
of deviation is unequal in different fields of
gaze
21. History
• Family History
• Age at Onset
• Type of Onset (gradual, sudden,
intermittent)
• Type of Deviation (comitant or incomitant)
• Fixation (one eye or alternating)
29. Examination Specific for Ocular
Motility
• Cover Test
• Uncover Test
• Alternate Cover Test
• Prism plus Cover Test
• Maddox Rod Test
• Hirschberg Test
• Krimsky Test
• Gaze Positions
• Convergence Measurement