ocular motility m.r besharati md shahid sadoughi university
TRANSCRIPT
Ocular MotilityOcular MotilityM.R Besharati MDM.R Besharati MD
Shahid Sadoughi UniversityShahid Sadoughi University
Eye MusclesLeft eye
Superior Oblique/Trochlear Muscle
Superior Rectus Muscle
Lateral Rectus Muscle
Inferior Rectus Muscle
Inferior Oblique Muscle
Medial Rectus Muscle
Anatomy Of The EOM’sAnatomy Of The EOM’s
What are the actions ofWhat are the actions of
EOM surround each eye:EOM surround each eye:
Anatomy Of The EOM’sAnatomy Of The EOM’s
The two The two ObliqueOblique are are AbductorsAbductors
The two The two RectiRecti are are AdductorsAdductors
The two The two SuperiorsSuperiors are are IntortersIntorters
The two The two InferiorsInferiors are are ExtortersExtorters
Anatomy Of The EOM’sAnatomy Of The EOM’s
OriginOrigin
A common A common tendinous ring tendinous ring (annulus of Zinn)(annulus of Zinn)
Anatomy Of The EOM’sAnatomy Of The EOM’s
Blood supplyBlood supply
Each muscle is supplied Each muscle is supplied by two Anterior Ciliary by two Anterior Ciliary
Arteries except the Lateral Arteries except the Lateral Rectus which is only Rectus which is only
supplied by one.supplied by one.
Anatomy Of The EOM’sAnatomy Of The EOM’s
Nerve supplyNerve supply
Third: LPS, MR, IR, Third: LPS, MR, IR, SR, IOSR, IO
Fourth: SOFourth: SO
Sixth: LRSixth: LR
Eye movementEye movement
Three directions of eye movement Vertically
Upward SR & IO Downward IR & SO
Horizontally Abduction LR Adduction MR
Torsionally Intorsion (rotate nasally) SO Extorsion (rotate temporally) IO
Ocular motilityOcular motility
Agonist Muscles: Receive equal innervation to ensure coordinated eye movements
Agonist/Antagonist Pairs (within each eye)Receive reciprocal innervation
Amblyopia: History
“When the doctor sees nothing and the patient sees nothing, the diagnosis is amblyopia.”
What’s Amblyopia?
Sometimes called “lazy eye”: characterized by:
Reduced visual acuity in an otherwise normal eye.
Onset early in life (typically before age 6)
Associated with a history of abnormal binocular visual experience.
Unilateral or less commonly, Unilateral or less commonly, bilateral reduction of best bilateral reduction of best corrected visual acuity that corrected visual acuity that can not be attributed directly can not be attributed directly to the effect of any structural to the effect of any structural abnormality of the eye or the abnormality of the eye or the posterior visual pathway. posterior visual pathway. Defect of central vision Defect of central vision
Unilateral or less commonly, Unilateral or less commonly, bilateral reduction of best bilateral reduction of best corrected visual acuity that corrected visual acuity that can not be attributed directly can not be attributed directly to the effect of any structural to the effect of any structural abnormality of the eye or the abnormality of the eye or the posterior visual pathway. posterior visual pathway. Defect of central vision Defect of central vision
Amblyopia
Prevalence: 2%-4% .Commonly unilateral Nearly all amblyopic visual loss is preventable or reversible with timely detection and appropriate intervention.Children with amblyopia or at risk for amblyopia should be identified at a young age when the prognosis for successful treatment is best. Role of screening is important
Prevalence: 2%-4% .Commonly unilateral Nearly all amblyopic visual loss is preventable or reversible with timely detection and appropriate intervention.Children with amblyopia or at risk for amblyopia should be identified at a young age when the prognosis for successful treatment is best. Role of screening is important
Amblyopia screening
Amblyopia: Definition
Uncorrectable, decreased vision in an otherwise structurally normal eye definition includes an
operated eye made “structurally normal” by surgery (e.g. post cataract surgery)
May be unilateral (most common) or bilateral
Associated (causative) Conditions:
Amblyopia is generally accompanied by:
strabismus, Anisometropia Isoametropia form deprivation Occlusive
e.g., one eye in focus (emmetropic)and the other out of focus (e.g. hyperopic)
Amblyopia usually seenwith hyperopic anisometropia
Anisometropic Amblyopia
AmblyopiaAmblyopiaFunctional reduction in visual acuity of an eye caused by
disuse/misuse during the critical period of visual development
•Strabismic Amblyopia – results from abnormal binocular interaction
•The visual cortex suppresses the image from one eye
•Long term suppression results in loss of vision
AmblyopiaAmblyopia
Amblyopia is the unilateral or Amblyopia is the unilateral or bilateral decrease of Vision bilateral decrease of Vision caused by form vision caused by form vision deprivation and/or deprivation and/or
abnormal binocular interaction abnormal binocular interaction for which there is no for which there is no obvious cause found by obvious cause found by physical examination of the physical examination of the eye.eye.
Can become irreversible Can become irreversible if not treated before if not treated before age 6 to 10 yearsage 6 to 10 years
ManagementManagement
First address vision impairment caused by First address vision impairment caused by amblyopiaamblyopia Prescription of glasses to correct refractive Prescription of glasses to correct refractive
errorserrors Occlusion therapyOcclusion therapy
AlignmentAlignment Medical Medical
Glasses with/without prismsGlasses with/without prisms PatchingPatching Visual training exercisesVisual training exercises
SurgicalSurgical
Occlusion TherapyOcclusion Therapy
Patching the eye with the Patching the eye with the better visionbetter vision
Full or part-timeFull or part-time Dependant on Dependant on
age/cause/severityage/cause/severity Forces use of amblyopic Forces use of amblyopic
eyeeye Improvement of V.AImprovement of V.A
Why We TreatWhy We Treat
1- Restore Stereopsis1- Restore Stereopsis
2- Prevent Amblyopia2- Prevent Amblyopia
3- Prevent Confusion and Diplopia3- Prevent Confusion and Diplopia
4- Appearance4- Appearance
Hirschberg TestHirschberg Test
ExotropiaNormalEsotropia
•Used as an initial screen for strabismus
•How it works:
•Stand several feet in front of child with penlight shining at eyes
•Light reflection will be at the same point in each eye
Cover TestCover Test
Child fixes on target (near or far)Child fixes on target (near or far) Examiner covers one eye while observing the Examiner covers one eye while observing the
opposite eye for movementopposite eye for movement No movement = normal ocular alignmentNo movement = normal ocular alignment Uncovered eye shifts to re-fixate on object = Manifest Uncovered eye shifts to re-fixate on object = Manifest
strabismus strabismus Indicates that the covered eye was the fixating eyeIndicates that the covered eye was the fixating eye
Cover-Uncover TestCover-Uncover Test
•Used to detect latent strabismus
•Child fixes on object (near or far)
•A cover is placed over one eye for a few seconds then rapidly removed
•The eye under the cover is observed for movement
Cover – Uncover test
Esophoria, abnormal, common
Only seen when eye is covered
Often asymptomatic, no complaints
Cover – Uncover test
Exophoria, abnormal, common
Only seen when eye is covered
Often asymptomatic, no complaints.
Alternate cover testAlternate cover test
Remember to allow the pt time to fixate on Remember to allow the pt time to fixate on the target, give them a minute.the target, give them a minute.
Then quickly cover the other eye to prevent Then quickly cover the other eye to prevent the pt from regaining fusion.the pt from regaining fusion.
But do not go back and forth quickly because But do not go back and forth quickly because the pt will not have time to refixate.the pt will not have time to refixate.
Alternate Cover test
Exotropia, intermittent
May be visible with or without alternate cover
May have intermittent diplopia, especially when tired or sick
Alternate Cover test
Exotropia, Constant
May be visible with or without alternate cover
May or may not have constant diplopia
Cover Uncover test
Left Exotropia, Constant
May be visible with or without alternate cover
Right eye preference
Cover Uncover test
Left Exotropia, Constant
May be visible with or without alternate cover
Right eye preference
Alternate Cover test with Prism
Exotropia, Constant
Use prism to quantitate the deviation.
Change prism power until movement is neutralized.
Use this number to plan surgery
20
How much to operate…
Why We TreatWhy We Treat
The main types of Amblyopia are:
1. Strabismic amblyopia results from abnormal binocular interaction where there is continued monocular suppression of the deviating eye. It is Characterized by an impairment of vision which is present even when the eye is forced to fixate.
Why We TreatWhy We Treat
2. Anisometropic amblyopia is caused by a difference in refractive error. It results from abnormal binocular interaction from the superimposition of a focused and unfocused image or from the superimposition of large and small images from aniseikonia.
3. Deprivation Amblyopia is caused from form vision deprivation of one eye.
Why We TreatWhy We Treat
- Confusion and Diplopia- Confusion and Diplopia
DEFINITIONSDEFINITIONS1. Visual axis is a line that passes through the point of fixation and the 1. Visual axis is a line that passes through the point of fixation and the
fovea. The normal visual axes intersect at the point of fixation.fovea. The normal visual axes intersect at the point of fixation.2. Strabismus is a misalignment of the visual axes which, initially, results in 2. Strabismus is a misalignment of the visual axes which, initially, results in
confusion and diplopia.confusion and diplopia.4. Diplopia is the simultaneous appreciation of two images of one object. it 4. Diplopia is the simultaneous appreciation of two images of one object. it
results from a failure to maintain binocular vision.results from a failure to maintain binocular vision.