Date post: | 12-Jan-2016 |
Category: |
Documents |
Upload: | theodore-thomas |
View: | 232 times |
Download: | 2 times |
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
internal rectus muscle
Lateral rectus muscle
Superior rectus muscle
Inferior rectus muscle
Superior oblique 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
primary position of eye
Right superior rectus muscleLeft inferior oblique muscle
Right lateral rectus muscle
Left internal rectus muscle
Right inferior rectus muscle
Left superior oblique muscle
Left superior rectus muscleRight inferior oblique muscle
Left lateral rectus muscle
Right internal rectus muscle
Left inferior rectus 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 strabismusTreatment: 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
Thank you!