Ocular MotilityOcular Motility

Dr. Tracy CrnicDr. Tracy CrnicPanhandle Eye Group and Texas Tech Panhandle Eye Group and Texas Tech Department of OphthalmologyDepartment of OphthalmologyPediatric Ophthalmology and Adult Pediatric Ophthalmology and Adult StrabismusStrabismus

BasicsBasics

Primary PositionPrimary Position Eyes pointed straight aheadEyes pointed straight ahead Tonic muscle action and orbital contents hold in placeTonic muscle action and orbital contents hold in place Without tonic action resting place of the eye is Without tonic action resting place of the eye is

divergentdivergent

Duction Duction movement of one eye irrespective of movement of one eye irrespective of the otherthe other Supraduction, infraduction, adduction, abduction, Supraduction, infraduction, adduction, abduction,

incycloduction, excycloduction (in or extorsion)incycloduction, excycloduction (in or extorsion)

Versions Versions movements of eyes togethermovements of eyes together

Movement of EyeMovement of Eye

Six Extraocular MusclesSix Extraocular Muscles Superior, Inferior, Medial and Lateral RectiSuperior, Inferior, Medial and Lateral Recti Superior and Inferior ObliquesSuperior and Inferior ObliquesPrimary, Secondary, and Tertiary functionsPrimary, Secondary, and Tertiary functionsMovement from Contraction of one or Movement from Contraction of one or more muscles with coincident relaxation of more muscles with coincident relaxation of othersothers

Origin of Muscles Origin of Muscles

Important for function of muscle Important for function of muscle where where contraction of muscle pulls contraction of muscle pulls towardtowardAnnulus of ZinnAnnulus of Zinn Muscular Muscular circlecircle behind globebehind globe All recti muscles (sup, inf, med, lat)All recti muscles (sup, inf, med, lat) About where bony orbit beginsAbout where bony orbit begins

Just above this at orbital apex is superior Just above this at orbital apex is superior oblique originoblique originOrbital floor near nose is inferior oblique originOrbital floor near nose is inferior oblique origin

Insertion of Muscle on EyeInsertion of Muscle on EyeSpiral of Tillaux Spiral of Tillaux musc create a musc create a spiral around spiral around corneal edgecorneal edge Medial Rectus 5.5 mm from limbusMedial Rectus 5.5 mm from limbus Inferior Rectus 6.5 mmInferior Rectus 6.5 mm Lateral Rectus 7.0 mmLateral Rectus 7.0 mm Superior Rectus 8.0 mmSuperior Rectus 8.0 mm

Superior Oblique Superior Oblique spread out under Superior spread out under Superior Rectus (first bending through troclea)Rectus (first bending through troclea)Inferior Oblique Inferior Oblique close to the macula (back of close to the macula (back of eye)eye)

Angle of InsertionAngle of Insertion

Horizontal Rectus muscles Horizontal Rectus muscles -- medial and lateral medial and lateral insert parallel to each other in a horseshoe insert parallel to each other in a horseshoe shapeshapeVertical Rectus muscles Vertical Rectus muscles superior and inferior superior and inferior insert 23 degrees temporal to the visual axisinsert 23 degrees temporal to the visual axisOblique muscles insert 50 degrees nasal to Oblique muscles insert 50 degrees nasal to visual axisvisual axisAllows for primary, secondary and tertiary Allows for primary, secondary and tertiary actionsactions

Laws of MotionLaws of Motion

SherringtonSherringtons Law s Law One muscle (agonist) contracts as another One muscle (agonist) contracts as another

muscle on the same eye relaxesmuscle on the same eye relaxesHeringHerings Law s Law you canyou cant move one eye at t move one eye at a timea time Each eye muscle has a Each eye muscle has a yokeyoke muscle in the muscle in the

other eye that contracts at the same time so other eye that contracts at the same time so both eyes move the same direction with the both eyes move the same direction with the same forcesame force

Exception convergence and divergenceException convergence and divergence

Neural InputNeural Input

Cranial Nerve 3 (Oculomotor Nerve)Cranial Nerve 3 (Oculomotor Nerve) Superior RectusSuperior Rectus Medial RectusMedial Rectus Inferior RectusInferior Rectus Inferior ObliqueInferior Oblique Pupil and EyelidPupil and Eyelid

Cranial Nerve 4 (Troclear Nerve)Cranial Nerve 4 (Troclear Nerve) Superior ObliqueSuperior Oblique

Cranial Nerve 6 (Abducens Nerve)Cranial Nerve 6 (Abducens Nerve) Lateral RectusLateral Rectus

AlignmentAlignment

Normal alignment is OrthotropiaNormal alignment is OrthotropiaAny abnormality in alignment is StrabismusAny abnormality in alignment is StrabismusManifest strabismus is HeterotropiaManifest strabismus is HeterotropiaHidden strabismusHidden strabismus is Heterophoria is Heterophoria Controlled by fusion, 2 foveas point same direction Controlled by fusion, 2 foveas point same direction

prevents deviationprevents deviation

Constant and IntermittentConstant and IntermittentPrefixes describe directionPrefixes describe direction Eso, Exo, Hyper, Hypo, CycloEso, Exo, Hyper, Hypo, Cyclo

AbbreviationsAbbreviationsEso Eso EEExo Exo XXHyper/ Hypo Hyper/ Hypo H H by convention H is hyper unless written out hypoby convention H is hyper unless written out hypo side refers to eye that is higher so RHT is same as side refers to eye that is higher so RHT is same as

LHypoTLHypoTTropia Tropia T (ex. Esotropia = ET)T (ex. Esotropia = ET)Phoria Phoria letter alone (ex. Esophoria = E)letter alone (ex. Esophoria = E)Intermittency Intermittency parenthesis (ex. E(T))parenthesis (ex. E(T))To indicate deviation at near use apostrophe To indicate deviation at near use apostrophe (ex. ET(ex. ET))

MeasurementsMeasurements

Prism Diopters Prism Diopters abbreviated with Delta or abbreviated with Delta or ^(up arrow)^(up arrow) Is a factor using millimeters of deviation from Is a factor using millimeters of deviation from

midlinemidline Measured with Prisms Measured with Prisms bend light traveling bend light traveling

through them at a certain anglethrough them at a certain angle Used to describe strabismus and guide Used to describe strabismus and guide

treatmenttreatment Ex. 30^ ETEx. 30^ ET Also can be abbreviated PDAlso can be abbreviated PD

Examination of MotilityExamination of MotilityVisual Acuity importantVisual Acuity important DonDont assume binocularityt assume binocularity Ability to fixate on object needed for many stepsAbility to fixate on object needed for many steps

Movement of eye in all 9 positions of gazeMovement of eye in all 9 positions of gaze Primary, up, down, right, left, 4 cornersPrimary, up, down, right, left, 4 corners Each has primary acting muscleEach has primary acting muscle Overaction and Underaction (ab. + or Overaction and Underaction (ab. + or 11--4)4)

Test both eyes individually (ductions) and Test both eyes individually (ductions) and together (versions)together (versions)Palsy versus Paresis versus Restriction results Palsy versus Paresis versus Restriction results in Strabismusin Strabismus

Red ReflexRed Reflex

Helpful for evaluation of alignment and Helpful for evaluation of alignment and fixationfixationEasily misinterpretedEasily misinterpretedAbnormal in Strabismus, Refractive Error, Abnormal in Strabismus, Refractive Error, and opacityand opacityBrucknerBrucknerCorneal Light Reflex Corneal Light Reflex should be centered should be centered in pupilin pupil

Examination of AlignmentExamination of Alignment

Use smallest target patient can discernUse smallest target patient can discern Not big E or penlight, can alter angleNot big E or penlight, can alter angle

Cover and UncoverCover and UncoverAlternate CoverAlternate CoverTests that estimate angle without requiring Tests that estimate angle without requiring fixationfixation Hirshberg Hirshberg based on where light reflex exists relative based on where light reflex exists relative

to pupilto pupil Krimsky Krimsky Centers light reflex inside pupil using Centers light reflex inside pupil using

prismsprisms

Cover and UncoverCover and Uncover

Place Occluder over right eyePlace Occluder over right eye-- then then uncover right eye and evaluate for uncover right eye and evaluate for refixation movement without covering refixation movement without covering other eyeother eyeRepeat for left eyeRepeat for left eyeEvaluates for presence of Tropia or Evaluates for presence of Tropia or Manifest deviationManifest deviation

Alternate CoverAlternate CoverPerform after above, breakage of fusion may Perform after above, breakage of fusion may alter numbersalter numbersFirst cover right eye then slowly move to left eye First cover right eye then slowly move to left eye while uncovering rightwhile uncovering rightRepeat in opposite directionRepeat in opposite directionEvaluates for presence of Phoria plus Tropia Evaluates for presence of Phoria plus Tropia (manifest and latent deviation)(manifest and latent deviation)Most accurate way to evaluate angle of Most accurate way to evaluate angle of StrabismusStrabismusNot useful if fixation not possible with one or Not useful if fixation not possible with one or both eyesboth eyes

Where do you put the Prism?Where do you put the Prism?

Point the prism apex toward the direction Point the prism apex toward the direction of the deviationof the deviationSoSo to correct an esodeviation point the to correct an esodeviation point the apex toward the noseapex toward the noseOR think of the light as bending toward the OR think of the light as bending toward the base of the prism so the image moves base of the prism so the image moves toward the direction of the deviated fovea toward the direction of the deviated fovea (not cornea) (not cornea) this is the more confusing of this is the more confusing of the two if you ask me.the two if you ask me.

How much prism?How much prism?

Continue adding prism (1Continue adding prism (1--50 in most sets) 50 in most sets) until the eyes quit moving back and forthuntil the eyes quit moving back and forthCalled Neutralization of the angleCalled Neutralization of the anglePrisms can be stacked but only if in Prisms can be stacked but only if in different directions.. To get measurement different directions.. To get measurement of angle greater than 50PD must add of angle greater than 50PD must add prism to other eye.. Air interface gives prism to other eye.. Air interface gives incorrect result.incorrect result.

What if you have more than one What if you have more than one direction of deviation?direction of deviation?

Many patients will have in and upMany patients will have in and up..So you use prisms in different directions So you use prisms in different directions simultaneouslysimultaneouslyEx. Pt. with esotropia and hypertropiaEx. Pt. with esotropia and hypertropia Place prism over one eye with base out and Place prism over one eye with base out and

other eye with base up or downother eye with base up or down May require another set of handsMay require another set of hands

Simultaneous Prism Cover Simultaneous Prism Cover

Used to measure tropia only component of Used to measure tropia only component of tropia/phoria mixtropia/phoria mixPlace prism and occulder simultaneously Place prism and occulder simultaneously over opposite eyesover opposite eyesEstimate angle of deviation first with Estimate angle of deviation first with corneal light reflexcorneal light reflexDifficult to interpretDifficult to interpret

Common pitfalls to strabismus Common pitfalls to strabismus measurementmeasurement

Target not small enoughTarget not small enoughVariable working distance or direction (of target)Variable working distance or direction (of target)Fusion not suspended (keeping other eye covered Fusion not suspended (keeping other eye covered prism bars help) canprism bars help) cant tell whatt tell whats phoria or tropias phoria or tropiaFixation not attained (you canFixation not attained (you cant neutralize a stare)t neutralize a stare)Refixation movements (patient may overshoot..)Refixation movements (patient may overshoot..)DonDont assume comitance (deviation may vary with gaze)t assume comitance (deviation may vary with gaze)Poor vision (inability to fixate) wear refractive correction Poor vision (inability to fixate) wear refractive correction but not prismatic correctionbut not prismatic correctionNystagmus Nystagmus if the patients eyes are moving for other if the patients eyes are moving for other reasons than strabismus, must measure with blur not reasons than strabismus, must measure with blur not occlusionocclusionFatigue (the patientFatigue (the patients) breakdown of angle can occurs) breakdown of angle can occur

So I have a primary deviation measured, So I have a primary deviation measured, now what?now what?

Remember those nine cardinal gaze positions?.... You Remember those nine cardinal gaze positions?.... You guessed it, repeat all that testing for each oneguessed it, repeat all that testing for each one.yep all 9 .yep all 9 and donand dont forget head tiltt forget head tiltAnd you have to do it again for near (important that near And you have to do it again for near (important that near is always 1/3 meter because distance can alter the is always 1/3 meter because distance can alter the amount of deviation amount of deviation our old friend accommodation)our old friend accommodation)Variable measurements in different directions of gaze is Variable measurements in different directions of gaze is Incomitance Incomitance occurs with over/underactionoccurs with over/underactionThis is how you determine which muscle is causing the This is how you determine which muscle is causing the problemproblem

What about Torsion?What about Torsion?Measurement of Rotation of the Measurement of Rotation of the eyeeyeDone with Maddox RodDone with Maddox RodPatient moves to align two Patient moves to align two straight lines to parallel positionstraight lines to parallel position

How do you determine if the How do you determine if the problem is a weakness or tightness problem is a weakness or tightness

of a muscle?of a muscle?Easiest way is to test forced duction or Easiest way is to test forced duction or generation.generation.Using forceps in Using forceps in numbnumb eye rotate eye in eye rotate eye in variable directionsvariable directionsTypically done at time of surgeryTypically done at time of surgery

So now we have a diagnosis, or do So now we have a diagnosis, or do we?we?

OkOk ready, cut ready, cut Hold on, first we have to figure out what Hold on, first we have to figure out what caused our problem.caused our problem.Surgery isnSurgery isnt always the best treatmentt always the best treatment. Just kidding right?. Just kidding right?NOPENOPE

EsotropiaEsotropiaCongenital or InfantileCongenital or InfantileAccommodativeAccommodativeDivergence insufficiencyDivergence insufficiencySensory EsotropiaSensory EsotropiaDuaneDuanes Syndromes SyndromeCongenital Fibrosis SyndromeCongenital Fibrosis SyndromeSixth nerve palsySixth nerve palsyMyasthenia GravisMyasthenia GravisPseudoesotropiaPseudoesotropiaThyroid OphthalmopathyThyroid Ophthalmopathy

ExotropiaExotropia

Intermittent ExotropiaIntermittent ExotropiaConvergence insufficiencyConvergence insufficiencySensory ExotropiaSensory ExotropiaCongenital ExotropiaCongenital ExotropiaRestrictive (entrapped muscle)Restrictive (entrapped muscle)ThyroidThyroid

Then there are neurological causesThen there are neurological causes

Yea.. The syndromesYea.. The syndromesDownDowns, Duanes, Duanes, Mobius, Brownss, Mobius, BrownsAnd Craniosynostosis.. The ever popular And Craniosynostosis.. The ever popular but politically incorrect FLK.but politically incorrect FLK.

Dissociated what?Dissociated what?

Dissociated vertical and horizontal Dissociated vertical and horizontal deviations.deviations.Drifting that occurs Drifting that occurs under the coverunder the coverCan be surgically corrected but isnCan be surgically corrected but isnt t usually necessaryusually necessaryControlled with fusionControlled with fusion

Now we know why, what do we do?Now we know why, what do we do?

Ohh Boy, we finally get to cut?Ohh Boy, we finally get to cut?MaybeMaybeFirst.. First.. Correct refractive errorsCorrect refractive errors Treat underlying conditions (amblyopia, thyroid, Treat underlying conditions (amblyopia, thyroid,

stroke, cataractstroke, cataract)) Wait (depending on cause) for stable angle Wait (depending on cause) for stable angle up to 6 up to 6

months and multiple measurements neededmonths and multiple measurements needed DonDont forget PRISM glasses in appropriate casest forget PRISM glasses in appropriate cases

Finally we get to OPERATE!Finally we get to OPERATE!Recession Recession weakens a muscle by moving it closer to weakens a muscle by moving it closer to the origin of the musclethe origin of the muscleResection Resection strengthens a muscle by shortening it (takes strengthens a muscle by shortening it (takes a piece out)a piece out)Transposition Transposition changes the angle of contact with the changes the angle of contact with the eye (moves a horizontal muscle up or down) altering its eye (moves a horizontal muscle up or down) altering its primary functionprimary functionTuck Tuck shortens a muscle without taking the piece outshortens a muscle without taking the piece outMyotomy Myotomy taking a muscle off and not putting it back on taking a muscle off and not putting it back on (also known as (also known as loosingloosing a muscle) haa muscle) haFaden procedure Faden procedure attaching the muscle to the sclera in attaching the muscle to the sclera in an additional placean additional placeCan do all above with part of or entire muscleCan do all above with part of or entire muscle

More surgeryMore surgery

Tendon expandersTendon expanders-- primarily on superior oblique primarily on superior oblique for Brownfor Browns syndromes syndromeAdvancement Advancement the undoing of a recessionthe undoing of a recessionBotulinum toxin Botulinum toxin partially paralyzes muscle that partially paralyzes muscle that is overactingis overactingOrbital procedures to remove masses, fix Orbital procedures to remove masses, fix fractures, or make more space (orbitotomy)fractures, or make more space (orbitotomy)Remove the Buckle, move the glaucoma implantRemove the Buckle, move the glaucoma implant

Important things your patients should Important things your patients should know about strabismus surgeryknow about strabismus surgery

2020--25% of anyone who needs eye muscle surgery will 25% of anyone who needs eye muscle surgery will require more than one in their lifetimerequire more than one in their lifetimeDouble vision is common after surgery but usually Double vision is common after surgery but usually resolvesresolvesThe eyes will be RED for a few weeks and may drain The eyes will be RED for a few weeks and may drain bloody tears for a day or sobloody tears for a day or soWe donWe dont take the eye out to operate on itt take the eye out to operate on itIt is not done with laser, incisions are going to be made It is not done with laser, incisions are going to be made and stitches usedand stitches usedSurgery does not improve vision but can prevent vision Surgery does not improve vision but can prevent vision losslossYouYoure never too old or too young for eye surgery or re never too old or too young for eye surgery or examinationexamination

There is no such thing as a There is no such thing as a stupid question!stupid question!

Not from a patient or from you!Not from a patient or from you!THANK YOU for your THANK YOU for your

attention!attention!

ReferencesReferences

American Academy of Ophthalmology, American Academy of Ophthalmology, Basic Clinical Basic Clinical Science Course Section 5: NeuroScience Course Section 5: Neuro--OphthalmologyOphthalmology, 2005, 2005--2006 ed., San Francisco, CA.2006 ed., San Francisco, CA.American Academy of Ophthalmology, American Academy of Ophthalmology, Basic Clinical Basic Clinical Science Course Section 6: Pediatric Ophthalmology and Science Course Section 6: Pediatric Ophthalmology and StrabismusStrabismus, 2005, 2005--2006 ed., San Francisco, CA. 2006 ed., San Francisco, CA. Kenneth W. Wright and Peter Spiegel, Kenneth W. Wright and Peter Spiegel, Pediatric Pediatric Ophthalmology and StrabismusOphthalmology and Strabismus, 2, 2ndnd ed., Elservier, Inc., ed., Elservier, Inc., 2003.2003.Duanes Ophthalmology On CDDuanes Ophthalmology On CD--romrom, Lippincott Williams , Lippincott Williams and Wilkins, 2002.and Wilkins, 2002.

Ocular MotilityBasicsMovement of EyeOrigin of MusclesInsertion of Muscle on EyeAngle of InsertionLaws of MotionNeural InputAlignmentAbbreviationsMeasurementsExamination of MotilityRed ReflexExamination of AlignmentCover and UncoverAlternate CoverWhere do you put the Prism?How much prism?What if you have more than one direction of deviation?Simultaneous Prism CoverCommon pitfalls to strabismus measurementSo I have a primary deviation measured, now what?What about Torsion?How do you determine if the problem is a weakness or tightness of a muscle?So now we have a diagnosis, or do we?EsotropiaExotropiaThen there are neurological causesDissociated what?Now we know why, what do we do?Finally we get to OPERATE!More surgeryImportant things your patients should know about strabismus surgeryThere is no such thing as a stupid question!References