2. ▪ Binocular vision – vision with both
eyes or ability to form one image of
the subject.
▪ Binocular: of or involving both eyes
at once
▪ BV: Vision wherein both eyes aim
simultaneously at the same visual
target
3. Advantages of the BV
▪ visual acuity is higher;
▪ visual field is wider,
▪ stereoscopic vision – ability of the
eye to estimate relative distance
between subjects, remote vision,
▪ and depth perception.
4. Processes of BV
▪Muscle balancing
▪Normal corresponding of retina
▪Retino-cortical pathway
▪Fusion
5. Panum fusional area. The left eye fixates a square target, and a search
object visible only to the right eye is moved before and behind this target.
The ellipse of retinal area, for which typical dimensions are given for the
parafoveal area, is the projection of the Panum fusional area. Diplopia is
not perceived for two targets within this area.
6. Vieth–Müller circle. If the eyes are assumed to be spherical with
rotational centers at the nodal points, all points in space that have a zero
disparity fall on this circle. Angle a1 = angle a2; thus, equal retinal
distances map into equal angles in space in this idealized system.
7. Positions of Gaze:
▪ The primary position – eye is directed
straight ahead.
▪ Secondary positions are straight up, down,
right, left gaze
▪ Tertiary – are the four oblique positions of
gaze: up and right, up and left, down and
right, down and left
▪ Cardinal positions: up and right, up and left,
right, left, down and right, down and left
9. Eye movements
Monocular – Ductions
▪ Adduction is movement of the eye nasally
▪ Abduction – temporally
▪ Elevation is an upward rotation
▪ Depression is a downward rotation
▪ Intorsion is defined as a nasal rotation of superior portion of
vertical corneal meridian
▪ Extortion – temporal rotation VCM
▪ Agonist – the primary muscle moving in given direction
▪ Synergist- the muscle in the same eye as agonist that acts
with agonist to produce a given movement
▪ Antagonist - the muscle in the same eye as agonist that
acts in the opposite direction of agonist
10. Eye movements
Binocular Eye movements – versions
and vergences
▪ Dextroversion is movement of both
eyes right
▪ Levoversion is movements left
▪ Elevation is upward rotation
▪ Depression – downward rotation
11. ▪ Vergences: convergence – is movement
of both eyes nasally relative to a given
position
▪ Divergence – is movement of both eyes
temporally to a given position
▪ Incyclovergence is rotation of both eyes,
VCM rotates toward
▪ Excyclovergence is rotation of both eyes,
VCM rotates away from medial plane
12.
13. Disturbances of eye movements:
▪ Orthophoria is the ideal condition of ocular
balance.
▪ Heterophoria is an ocular deviation kept
latent by the fusional mechanism (latent
strabismus).
▪ Heterotropia is a deviation that is manifest
and not kept under control by the fusional
mechanism (manifest strabismus).
▪ Nistagmus
14. The investigation of strabismus
▪ Worth 4 dot test
▪ Cover test
▪ Bagolini test
▪ Synoptophore
▪ Test for stereopsis
▪ Kalfa test
▪ Test – hole in the palm
15. Measurement of angle of deviation
▪ Hirschberg test – position of light reflex
at the border of pupil -15°of deviation
or at the center of iris – 30° or at the
cornea margin – 45° or more
▪ Prism test
▪ Synoptophore
16. Hirschberg light reflex method. The patient has a left
esotropia. Note the corneal light reflex at the temporal
pupillary border of the left eye while the reflex is centered in
the pupil of the right eye.
17. Krimsky light reflex method. The strength of a base-out prism
over the fixing right eye sufficient to center the pupillary light
reflex in the esotropic left eye is defined as the amount of left
esotropia.
18. Fusion – is the cortical unification of visual
objects into a single percept that is made by the
simultaneous stimulation of corresponding
retinal areas
▪ Sensory fusion is based on the iinate
topographic relationship between the retinas
and visual cortex
▪ Motor fusion is vergence movement that
causes similar retinal images to fall and be
maintained on corresponding retinal areas
19. Cover test. B, The patient’s right eye is examined
for movement as the left eye is covered.
20.
21. Simultaneous prism and cover test with right eye fixing.
The prism is moved before the fixing right eye simultaneously
with the cover held before the left eye.
22. ▪ Red Maddox rod. A red
Maddox rod in a trial frame may
be used to evaluate subjective
ocular torsion. The grooves
must be aligned with the mark
on the rim, as they tend to rotate
within.
▪ Maddox rod. A series
of aligned strong
cylinders, here placed
in a paddle handle.
23. Possible Worth four-dot percepts in binocular patients. Note the
similar distant responses in patients who have esotropia with abnormal
retinal correspondence (ARC) and suppression and in those who have
monofixation syndrome. Patients who have exotropia with ARC and
suppression give the same responses, but the suppression scotoma is
larger and shaped somewhat differently . The red lens is over the right
eye and the green lens over the left eye.
24. Possible Worth four-dot responses in patients
who do not have binocularity. The red lens is over
the right eye and the green lens over the left eye.
25. ▪ Bagolini lenses. Placed at
135° orientation in the trial
frame before the patient’s
right eye and at 45° before
the patient’s left eye.
Possible Bagolini
lens percepts, central
fixation.
29. Classification of Str.
▪ Comitant, incomitant or paretic
▪ Latent or manifest
▪ Direction of deviation
▪ Monolateral or alternative
▪ Accomodative, nonaccomodative
▪ With or without amblyopia
30. Comitant Str.
▪ Onset is usually early in young children
▪ Gradually
▪ Without diplopia
▪ Movements of eye are kept
▪ Primary and secondary angles of deviation
are equal
31. Incomitant Str.
▪ Onset in any age and sadden
▪ Constriction of eye movement in side of
paretic muscle
▪ Presence of diplopia
▪ Primary angle of deviations more than
secondary
32. Treatment of Str.
▪ -Pleopto – orthopto – diplopto-surgical
treatment
▪ Pleoptoorthopto – purpose to increase
visual acuity
▪ Diplopto – to get physiological diplopia
and fusion
33. Adult who has a partial left third nerve palsy. A, Primary
gaze showing slightly larger pupil, mild ptosis, left exotropia,
and left hypotropia.
34. ▪ Adult who has a
partial left third
nerve palsy. B,
Normal left gaze.
Adult who has a
partial left third nerve
palsy. C, No adduction
of the left eye on right
gaze.
35. ▪ Adult who has a partial
left third nerve palsy.
D, Poor elevation
Adult who has a partial
left third nerve palsy. E,
Poor depression.
36. ▪ Elderly woman who
has complete left
third nerve palsy. A,
Complete ptosis, left
eye.
Young woman who has
idiopathic left fourth
nerve palsy. A, Primary
position left hypertropia
from loss of the depressor
effect of the paretic left
superior oblique muscle.
37. ▪ A 1-month-old infant who
has congenital right
sixth nerve palsy. A, Little
or no deviation in
contralateral (left) gaze.
▪ Young woman who has
idiopathic left fourth nerve
palsy. B, Normal motility in left
gaze, away from the fields of
action of the paretic left superior
oblique muscle.
38. A 33-year-old man who has a right sixth nerve
palsy. A, Right esotropia in primary position.
39. Full-tendon “transposition” of the superior and inferior
rectus muscles to the insertion of the left lateral rectus
muscle.
42. Prism adaptation test. A child with esotropia is wearing a
Fresnel membrane prism over the left eye, of sufficient
strength to neutralize the esotropia.
