Transcript internal rectus muscle Lateral rectus muscle Superior rectus muscle

Extrinsic muscles and
Amblyopia
The Fourth Affiliated Hospital of China
Medical University
Ophthalmology Hospital of China
Medical University
Extrinsic muscles
• The globles depend on the contraction and relaxation
of extrinsic muscles to give rises coordinate
movement. There are 4 recti and 2 oblique muscles in
each eye.
Superior rectus muscle
Inferior rectus muscle
※ Motor function of extrinsic muscle
Main function
The sccond function
internal rectus muscle
abduction
Lateral rectus muscle
outwards
Superior rectus muscle
upwards
abduction and intorsion
Inferior rectus muscle
downwards
adduction and extorion
Superior oblique
muscle
intorsion
downwards and
outwards
Inferior oblique muscle
extorsion
upwards and outwards
Motor function of extrinsic muscle
Superior oblique
muscle
internal rectus
muscle
Inferior rectus muscle
Superior rectus
muscle
Lateral
rectus muscle
Inferior oblique
muscle
Motor function of extrinsic muscle
Motor function of extrinsic muscle
Synergist and Sntagonist
• Synergist: simple eye
• Sntagonist: simple eye
Yoke muscles
Right superior rectus muscle
Left inferior oblique muscle
Right lateral rectus muscle
Left internal rectus muscle
Left superior rectus muscle
Right inferior oblique muscle
primary position
of eye
Left lateral rectus muscle
Right internal rectus muscle
Right inferior rectus muscle
Left inferior rectus muscle
Left superior oblique muscle
Right superior oblique muscle
Cardinal positions and yoke musclec
Strabismus
• Definition : both eyes can’t be fixed on the
target simultaneously and the optic axes are
divergent. one eye is fixing on the target and
the other eye is deviating from it.
Strabismus
Check of strabismus
§ History taking
§ Inspection
§ Visual acuity examination
§ Refraction examination
§ Qualitative and quantitative examination of strabismus
a. Cover test
b. Corneal reflection of light point
c. Triangular prism
d. Examination of synoptophore
e. Diplopia test
f. Bielschowsky test
g. Visual apperception test
Cover test
1.alternative cover test
2.cover-uncover test
Corneal reflection of light point
Corneal reflection of light point (Hirschberg)
It is the most simple but commonly used method to determine the
angle of strabismus.
Triangular prism
The base of prism towards outside in esotropia,
towards inside in exotropia.
Examination of synoptophore
Diplopia test
Analytical procedure of diplopia diagram
1.Determine the diplopia is horizontal or vertical at first.
2.In horizontal one, if it is crossed, it indicates exotropia .
if it is ipsilateral, it indicates esotropia.
In vertical one, if the moved image is higher, indicating the
paralytic eye is lower than the healthy one.
3.Determine the biggest direction of diplopia .
The crossed diplopia in right exotropia
Bielschowsky test
Visual apperception test
• Sensory adaptation is important to realize that
pathological suppression ,ARC and amblyopia
develop only in the immature visual system.
• Classification: (1) test of suppression
(2) test of sensory fusion
(3) test of stereopsis
Classification of strabismus
• 1. esotropia
• 2.exotropia
• 3.A and V patterns strabismus
• 4.vertical strabismus
Esotropia
• Concomitant esotropia
(1)non-accommodative esotropia
congenital esotropia
(2)accommodative esotropia
(3)part accommodation esotropia
• Paralytic esotropia
Esotropia
Concomitant esotropia
• Congenital esotropia: it is a constsnt esotropia with 6 month
after birth. The angle of squint is equal and constant for seeing
far and near. The strabismus can’t be corrected by glasses,with
less relation to ametropia.
• Treatment: the operation could be done after treatment of
amlyopia.
accommodative esotropia
For the hyperopia isn’t corrected ,over use of
accommdation induces too strong convergence plus the
hypofunction of fusion divergence to cause esotropia.
Part accommodation esotropia
Paralytic esotropia
Clinical findings:
Diplopia and Vertigo, Compensatory head position, Limitation of
motion, 2nd angle of strabismus >1st angle of strabismus
Treatment:
Only when the etiology has been got of and optical therapy has
been given for 6 months, does the surgery be considered.
exotropia
Incidence of exotropia is smaller than one of esotropia, especially
for children.
• Classification:
(1) Intermittent exotropia: it hasn’t relation with ametropia in
general. The age of onset is often about 1 years old, but it is
obvious at about 5 years old. It shows angle increase when
fixating at distant.
(2) Constancy exotropia: incidence of constancy exotropia is
smaller than one of Intermittent exotropia.
• Treatment: surgery
intermittent exotropia
A and V patterns strabismus
• An A pattern is present when a horizontal deviation
shows a more convergent alignment in upgaze
compared with downgaze.
• V pattern describes a horizontal deviation that is more
convergent in downgaze compared with upgaze.
• A clinically significant A pattern is one that measures
10△. A clinically significant V pattern is one that
measures 15△.
• Treatment: surgery
Vertical strabismus
• Incidence of it is small. Usually acquired
when growing up.it is named according to
topper eye.
Amblyopia
• Amblyopia is due to congenital or
insufficient light stimulation entering
the eye at critical period of
development.
Classification of amblyopia
• Classification:
(1)strabismic amblyopia
(2)ametropia amblyopia
(3) amblyopia by visual deprivation
• Treatment: the younger the age is ,the better the
therapeutic effect becomes.
Nystagmus
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