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:

Medial Rectus Medial Rectus

AdductionAdduction

Lateral Rectus Lateral Rectus

AbductionAbduction

Superior Rectus Superior Rectus

Elevation,Elevation, Adduction,Adduction, IntorsionIntorsion

Inferior Rectus Inferior Rectus

Depression,Depression,Adduction,Adduction, ExtorsionExtorsion

Superior Oblique Superior Oblique

Intorsion, Intorsion, Depression,Depression, AbductionAbduction

Inferior Oblique Inferior Oblique

ExtorsionExtorsionElevationElevation AbductionAbduction

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

OriginOriginA 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 supplyThird: LPS, MR, IR, Third: LPS, MR, IR,

SR, IOSR, IOFourth: SOFourth: SOSixth: LRSixth: LR

Ocular motilityOcular motility

CN IV

CN VI

CN III

CN III

CN III CN III

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

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

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

Strabismus refers to an eye-turn.

normal

F F F F

esotropia

e.g., one eye in focus (emmetropic)and the other out of focus (e.g. hyperopic)

Amblyopia usually seenwith hyperopic anisometropia

Anisometropic Amblyopia

Monocular Form Deprivatione.g., cataract.

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 Stereopsis2- Prevent Amblyopia2- Prevent Amblyopia3- Prevent Confusion and Diplopia3- Prevent Confusion and Diplopia4- Appearance4- Appearance

Strabismus measurment

Hirschberg TestHirschberg Test

ExotropiaNormal Esotropia

•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 testOrthophoria, normalNo complaints, asymptomatic

Cover – Uncover testEsophoria, abnormal, commonOnly seen when eye is coveredOften asymptomatic, no complaints

Cover – Uncover testExophoria, abnormal, commonOnly seen when eye is coveredOften 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 testExotropia, intermittentMay be visible with or without alternate coverMay have intermittent diplopia, especially when tired or sick

Alternate Cover testExotropia, ConstantMay be visible with or without alternate coverMay or may not have constant diplopia

Cover Uncover testLeft Exotropia, ConstantMay be visible with or without alternate coverRight eye preference

Cover Uncover testLeft Exotropia, ConstantMay be visible with or without alternate coverRight eye preference

Normal ConvergenceConvergence Insufficiency

Alternate Cover test with PrismExotropia, ConstantUse 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 TreatThe 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.