Binocular Vision

True Angle of Anomaly

*Angle of Anomaly + Eccentric Fixation angle = *

Hess-Lancaster test (steps for finding Underacting muscle)

1. Which graph from which eye is the most compact (smaller)? this is the affected eye, and is the eye with the *Underacting* muscle (which is the muscle of interest) 2. Then the other larger graph is your good eye, which has the muscle that is Overacting 3. On the affected eye, which is the gaze that is furthest from expected values?

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CN III

Congenital (rare) : down and out oExotropia(weakness of medial rectus) oHypotropia(weakness of superior rectus and inferior oblique) oLimited depression in abduction (weakness of inferior rectus) oPtosis (poor levatorfunction) oDilated fixed pupil oMay see only superior or inferior branch affected oMay see with congenital aberrant regeneration of the nerve •New axons are misdirected to innervate appropriate muscles

Moderately embedded AC

Depth of AC type: •Present on 2 tests (bagoliniand W4D or VPA) •Occurs in smaller angle strabswith stable angles

Deeply embedded AC

Depth of AC type: •Present on 3 or more tests (bagolini, W4D, VPA) •Occurs in small angle strabs(microtropes)

Shallow or Mild

Depth of AC type: •Present only on bagolinitest (most natural test: similar to natural view conditions) •Occurs in moderate to large angle strabs •Occurs in variable angle strabs oIntermittent Exotropes/Divergence Excess

Eccentric Fixation

Direction oSuperior, inferior, temporal, nasal, superior nasal, inferior nasal, superior temporal and inferior temporal Distance from the fovea to the eccentric point oMeasured in prism diopters Degree of steadiness oSteady eccentric or central fixation oUnsteady eccentric or central fixation these are used to describe:

Same Same Opposite Opposite Same

Directions of movement: Head Turns in the _____ direction as affected DAF Head Tilts are seen in the _____ direction, if the Inferior oblique is affected Head Tilts are seen in the _____ direction, if the Superior oblique is affected Eyes Turn in the _____ direction, as the affected DAF Chin Tips are seen in the _____ direction in which the deviation is worse

Duanes Retraction syndrome

Etiology oInnervation goes to both the MR and LR by the 3rdnerve causing contracting of both muscles, resulting in retraction of the globe, partial limitation of adduction and narrowing of the palpebral fissure •15-20% bilateral •May have anomalous head posture

Anomalous Correspondence vs Suppression

Factors contributing to either Suppression or Anomalous correspondence, or both: •Age of Onset oEarly onset strabismus (before/during critical period) •SUPPRESSION and/or AC oLate onset •DIPLOPIA •Magnitude of the Strabismus oLess than 10 pd •AC very likely oLess than 20 pd •AC moderately likely o20-30 pd •AC less likely and suppression more likely oGreater than 30 pd •SUPPRESSION

right superior oblique is underacting that means left inferior rectus is overacting

Hess-Lancaster test example: which muscle is the affected one?

•Smaller graph = Right Eye oaffected eyes muscle field (underacting) •Larger graph = left eye oGood eyes muscle field (overacting) •Muscle affected = Right eye opositon of gaze is the furthest from expected position = looking to the right •RIGHT LATERAL RECTUS PALSY

Hess-Lancaster test example: which muscle is the affected one?

Anomalous Correspondence

Name the points on the retina for AC: oZero point = point z : Point on the retina in the deviated eye in which the fixation object is imaged oAssociated point = point a : the retinal point in the deviating eye which when stimulated gives rise to the same visual direction of the fovea of the fixating eye (point A is the corresponding retinal point to the fovea in the fixating eye) •Point A can be the fovea of the deviated eye, the Z point or any other retinal point oFovea = f

Anomalous Correspondence

Object imaged on non-foveal corresponding retinal point to the fovea of the non-deviated eye

Unharmonious Anomalous Correspondence (UHAC)

Object imaged on non-foveal, non-corresponding retinal point to the fovea of the non-deviated eye

1. CTis done in primary gaze, which eye is Hyper? 2. CT done in left & right, does the Hyper increase on right or left gaze? 3. CT done with Head Tilted to the left & right, does the Hyper increase on right or left head tilt?

Parks 3 Steps

Harmonious Anomalous Correspondence (HAC)

Patient who is an exotropewho does not experience suppression or diplopia. Is using a retinal point other than the fovea in the deviating eye

affected eyes muscle field (Primary deviation -Underaction) sound eyes muscle field (Secondary deviation = Overaction of the yoked muscle) positon of gaze is the furthest from expected position in the Underacting eye

Results of Hess-Lancaster test •Smaller graph = ? •Larger graph = ? •Muscle affected = ? *****Can have more than 1 muscle affected that shows on this graph

(+) Positive sign

Signs: oEso reponse oUncrossed diplopia oNasal eccentric fixation oBO oCrossed foveal tag

Anomalous Correspondence

are risk factors for this: •Strabismus is present in early childhood oMore likely in ET than XT •The magnitude of the deviation is less than 30 pd •Strabismus is constant and of the same magnitude at distance and near •Can be unilateral or alternating strabismus One exception: oIntermittent exotropeand divergence excess patient can show NC when their eyes are aligned, but AC when their eyes are deviated

Eccentric Fixation

are tests to measure: •Visuoscopy •HaidingerBrush •Brock-GivnerAfterimage Test •Clinically we measure this in prism diopters with these 2 tests

Brown's Syndrome

condition where Eye will not elevate when adducted •Divergence in upgaze (V pattern) •May have a hypotropiain primary gaze •Binocular 10% of the time

Duanes Retraction syndrome

condition where the Globe is retracted and the palpebral fissure is narrowed when ADDuctionis attempted

Horror Fusionis

condition where you give a patient prism, but they can never Fuse •Inability to obtain binocular fusion or superimposition of haploscopicallypresented targets •Condition in which targets approaching superimposition may seem to slide or jump past each other without apparent fusion or suppression •Patient has diplopia in which prism likely will not eliminate the diplopia •Mechanism is uncertain, but associated with ARC oThe fovea of the fixating eye has many corresponding retinal points in the deviated eye •Occurs more in anisokonia

Indirect Projection

dysfunction where Direction of the target seen by the deviated eye is perceived in the opposite direction of the actual deviation •Example: right lateral rectus palsy with the red lens over the right eye. oThe red light actually looks further away in right gaze, but the patient can not ABDuctthat eye

Hypo Exo

in Double Maddox rod test if: Red line is above green = ? Red line outward = ? vertical line top top tilted outwards = ?

Anomalous correspondence (AC) w/ Eccentric Fixation

in Hering Bielshowsky Afterimage test patient that Does Not have Central Fixation experiences: oThe foveasno longer correspond oEF point is tagged oPatient may see a perfect cross if the EF point corresponds to point A (the corresponding point to the fovea in the fixating eye) •Points A and EF are in the same location on the retina (microstrab) oEF and point A are usually not in the same location and therefore you may not see a perfect cross, but EF and point A are usually both in the same direction

Normal correspondence (NC) w/ Eccentric Fixation

in Hering Bielshowsky Afterimage test patient that Does Not have Central Fixation experiences: oThe patient will NOT see a perfect cross oThe amount of separation between the horizontal and vertical AI is equal to the amount of EF •The foveasstill correspond *The EF point in the deviated eye becomes tagged* *•Nasal EF: the vertical line will be temporally projected •Temporal EF: the vertical line will be nasally projected*

Normal correspondence (NC)

in Hering Bielshowsky Afterimage test patient that has Central Fixation experiences: Perfect Cross oFoveaswere both stimulated, a perfect cross will be perceived regardless of the direction in which each eye is positioned •Eye could be in eso, exo, hyper or hypo position oAngle A = 0

Harmonious Anomalous correspondence (HAC)

in Hering Bielshowsky Afterimage test patient that has Central Fixation experiences: oFoveasno longer correspond oFoveasgive rise to different visual directions oPoint A is the representational point of the fovea in the deviating eye oThe amount of separation is equal to angle A = objective angle oThe amount of the separation is equal to the magnitude of the strabismus *Crossed foveal tag = Eso(+) sign •Uncrossed foveal tag = exo(-) sign*

Unharmonious Anomalous correspondence (UHAC)

in Hering Bielshowsky Afterimage test patient that has Central Fixation experiences: oFoveasno longer correspond oFoveasgive rise to different visual directions oPoint A is the representational point of the fovea in the deviating eye oThe amount of separation is equal to angle A, but not equal to the objective angle oThe amount of separation is not equal to the magnitude of strabismus

Right Superior Oblique palsy

in double maddox rod test this pt: eye appearance: right eye Hyper & Excyclotorted Fovea: red line is Above & left side of line is superior to temporal retina Patient's view: red line is Inferior and Incyclotorted (tilted nasally)

Dissociated Vertical Deviation (DVD)

in this dysfunction: there will be sopntaenous turning of either eye Upward, when the pt is fatigued, fusion is interrupted you will see a Double Hyper deviation (alternating hyperphoria), (no hypo) is associated with Infantile Esotropia, Exotropia, and Latent Nystagmus

Dissociated Vertical Deviation (DVD)

in this dysfunction: where one eye receives innervation to involuntary move up (and vision is suppressed) the patient is rarely symptomatic (no diplopia) poor potential for normal BV Treatment for these patients involve Monitoring and Sx if significant asymmetry

Hering Bielshowsky Afterimage

in this test You will use an afterimage flash in the horizontal orientation to tag the fovea of the fixating eye (occlude deviating eye) •You will then turn the flash vertically and tag the strabismic eye (occlude fixating eye) •You will then have the patient look at the AI chart, 1 meter away from them oPatient will fixate at the red dot oThe grid is so that every 1 cm = 1 pd oIn a bright room the patient can see dark negative after-images by looking at a white background oIn a dark room or by closing your eyes, the patient can see orange-red positive after-images.

Visuoscopy

in this test: wherever the reticule of the ophthalmoscope is when compared to the fovea, is the type of eccentric fixation that it is if reticule is Nasaly to fovea = Nasal EF if reticule is Temporal to fovea = Temporal EF make sure you know which eye it is, b/c different results

Visuoscopy

in this test: •Using an ophthalmoscope the doctor will observe on the fundus: the reticule oPatient is COVERING ONE EYE. *THIS IS A MONOCULAR PROCEDURE* oAsk the patient to look in the center of the reticule and keep fixation nice and steady oDoctor will observe where the fovea is in relation to where the center of the reticule is the eye that is looked into is the "Strabismic" eye

Brown's Syndrome

is a Mechanical anomaly oInelastic, short or thickened tendon oTrochleror tendon-trochlear complex abnormality oCan also have an acquired case: •Trauma •Damage/scarring after scleral buckle sxor EOM sx •Positive forced duction •Treatment oMonitor oSx

Torticollis (head tilt)

is a congenital condition Present at birth due to primary contracture of the sternocleidomastoid muscle on one side

Hess-Lancaster test

is a subjective test where: •Patient wears red/green anaglyph glasses •The eye muscle fields of the right and left eyes are plotted (graphic representation) o It is done with the right eye fixating and then the left eye fixating •When comparing the 2 fields, you can determine the restricted field and therefore the paretic muscle

Parks 3 steps

is a test used to isolate Vertical deviations they isolate cyclo-vertical muscles so it does not test for lateral and medial muscles

Hess-Lancaster test

is the Most sensitive test for Noncomitancy oHowever... •If there is anomalous retinal correspondence, suppression or poor cooperation by the patient: Poor results/unable to perform

(-) Negative sign

oExoresponse oCrossed diplopia oTemporal eccentric fixation oBI oUncrossed foveal tag

Corresponding Retinal Points

occurs when: •Pairs of points, when stimulated simultaneously or rapidly in succession, are perceived to lie in identical visual directions the point on the temporal OS, corresponds to the nasal point on OD which are in the same visual direction

Direct Foveal projection

situation where: the pt will project the light in the same direction as that of deviating eye each fovea perceives the image from its perspective

Maddox Rod / Red lens test

test is used to find affected muscles in Vertical deviations Place the lens over the Right eye* the affected muscle is in the gaze in which the red line is furthest from the light this is the point where the pt experiences the most diplopia

Hess-Lancaster test

the doctor holds the red light this red light signifies the Fixating eye green light = eye of the field that were testing this test is opposite of maddox rod right gaze = right side left gaze of OD = left gaze if their green laser points to the left of red (doctor) then OS muscles = overacting (left lateral rectus is paretic, right medial rectus turns in with it) if their green laser points to the rightt of red (doctor) then OS muscles are = underacting to test the other eye, pt can either flip glasses or switch lasers with doctor on a white background, the green laser is the only one that is seen, red light on OD (w/ red filter over it) will only see all red (so does not work)

Non-Comitant deviation (acquired)

these are a type of non-comitant deviations: •Recent onset diplopia variations in different directions of gaze •Asthenopia •Blurred vision CNIII: ciliary muscle •Dizziness or Vertigo Changes in retinal image

Head Tilts

these movements can give you a clue on a deviated Cyclo muscle only, involving either the Superior oblique or Inferior oblique

Duanes Retraction syndrome (Type I)

these patients experience: •Limited ABDuctionin the affected eye •Retraction of the globe and narrowing of the palpebral fissure on ADDuction •Can look orthoin primary gaze or slightly eso

Duanes Retraction syndrome (Type III)

these patients experience: •Limited ADDuction and ABDuction •Retraction of the globe and narrowing of the palpebral fissure on ADDuction

Duanes Retraction syndrome (Type II)

these patients experience: •Limited ADDuctionin the affected eye •Retraction of the globe and narrowing of the palpebral fissure on ADDuction

Chin Tips

these physical movements are seen in A & V pattern deviations, and can give you a clue on which muscle is the affected DAF

Anomalous Correspondence

these steps test for: •Objective angle of deviation (H or D) oMagnitude of strabismus that is measured on alternate cover test •Subjective angle of deviation (S) oDistance on the retina between thez point and the a point oCan be measured with prism •Difference between the objective and subjective angle is the angle of anomaly (A) oAngular separation between the anatomical fovea of one eye and the point in that eye which corresponds to the fovea of the other eye A = H - S

A & V pattern

these type of deviations have a dysfunction of the Oblique muscles

Anomalous Correspondence

this can Only occur in strabismus patients under binocularviewing conditions oUnder monocular conditions, the fovea retains the primary visual direction •unless the patient has EF

V pattern

this dysfunction has a overaction of the Inferior Oblique, & underaction of the Superior oblique they have no vertical deviation in the primary gaze but in the right or left gaze, in the eye that is supposed to adduct you will see overaction (Hyper)*

A pattern

this dysfunction has a overaction of the Superior Oblique, & underaction of the Inferior oblique they have no vertical deviation in the primary gaze but in the right or left gaze, in the eye that is supposed to adduct you will see overaction (Hypo)*

Confusion

this happens when: o2 different objects are stimulating corresponding retinal points oImages appear to be on top of one another •Eye suppresses as a mechanism to get rid of confusion there is EF, but both objects still hit both foveas

Diplopia

this happens when: oStimulation of non-corresponding retinal points of the same image oThe same object is perceived 2 x oOccurs in Late onset strabismus •Eye may suppress as a mechanism to avoid diplopia

Normal Retinal Correspondence (NRC)

this happens when: •When the foveas and retinal points of the fixating eye and deviating eye correspond, giving rise to the same visual direction

Suppression

this happens: •To avoid diplopia and confusion •Cortical inhibition of one eye under binocular conditions •Size (foveal, central or peripheral) oSize of the zone increases with the size of the deviation •Intensity: shallow to deep oThe deeper the suppression the more frequent the eye turn

Eccentric Fixation

this is Seen in Amblyopic Patients oStabismicAmblyopes oAnisometropicAmblyopes

Hering Bielshowsky Afterimage

this test Directly Measures Angle A (Angle of anomaly) oFovea to Fovea cortically but Before beginning this test you Must know if patient has Eccentric Fixation or central fixation Do VISUOSCOPY first

Double Maddox Rod

this test can be used to detect Cyclo deviations the lenses are placed at 180 degrees (pt sees 2 vertical lines) vertical lines will be superimposed if pt has no horizontal deviation

A pattern

this type of deviation in: Esotropia increases in upgaze, and decreases in down Exotropia increases in downgaze, and increases in up they have Non-commitant deviations they do not every see double these pts don't have paretic muscles, or palsies

V pattern

this type of deviation in: Exotropia increases in upgaze, and decrease in down Esotropia increases in downgaze, and decrease in up they have Non-commitant deviations they do not every see double these pts don't have paretic muscles, or palsies

Non-Comitant deviation

when a pt has these signs/symptoms suspect: Anomalous head posture on direct observation (bring in old photographs) And/or Obvious over or underactionson versions And/or Recent onset of diplopia And/or Recent trauma

Noncomitant

when the eyes have different magnitudes of gaze, when forced to look at different directions during to test the magnitude of the affected muscle, the prism must be over the un-affected eye they are V & A pattern deviations

Left Lateral rectus palsy

which is the affected muscle?

Eccentric Fixation

•An eye with 20/20 VA generally has central, steady VA (assuming no pathology) •An eye with eccentric fixation has VA worse than 20/20 o20/(EF + 1)20 •EF in pd oEven worse if fixation is unsteady •An eye with unsteady central fixation has VA worse

Eccentric Fixation

•Any area of the retina, other than the fovea, is used for fixation *Under Monocular conditions* oFixate with fovea = central fixation oFixate off fovea = eccentric fixation •Can be steady or unsteady: irregular flicks or drifts oFixate with fovea = central fixation •Steady central •Unsteady central oFixate off fovea = eccentric fixation •Steady eccentric •Unsteady eccentric

Mobius Syndrome

•Bilateral sixth nerve palsy oPatient can not abduct (esotropia) oAssociated with bilateral facial nerve palsy (CN VII) •Poor facial musculature •Congenital •Other signs oMental retardation oHearing, speech deficits oHeart defects oLimb and chest deformities

Skew Deviation

•CN IV differential oVertical diplopia + head tilt •BUT.....comitanthypertropia(in some cases varies in different positions of gaze) •BUT....lateral head tilt toward hypertropiceye oHypertropiceye found to be incyclotorted oSo when you make the patient supine...amplitude of deviation decreases •Lesion of prenuclearvestibular input to ocular motor nuclei within cerebellum or brainstem

CN III

•Can have many different presentation depending on which portion of the nerve is affected •Acquired oCan be full or partial oWhen EOMs and pupil is involved= internal ophthalmoplegia(eye is down and out).....refer for imaging •Compressive lesion oAneurysm oTumor oTrauma oWhen EOMs without pupil involvement = external ophthalmoplegia •Vascular in nature (control systemic conditions...resolve over time) oDM oHTN •Acute presentation...need to refer for imaging STAT...could be aneurysm that is sparing pupil now, but evolving compressive lesion oMonitor daily

CN IV

•Causes oCongenital •Longstanding (may not c/o diplopia, will have good vertical fusional vergenceranges, may have overactionof IO, no excyclotorsionon double maddoxrod) oHead trauma!!! •Very susceptible as it emerges dorsally from the medullary velum oVascular in nature (DM, HTN) oMS, MG oTumor •What will you see? oHypertropiaand excyclodeviation(acquired) in primary gaze that increases in downgazeand with convergence •Most common cause of a vertical deviation oHead tilt to Opposite shoulder oIf bilateral (trauma) •Increase of a hyper on right and left head tilt •Double excycloon double maddoxrod

Eccentric Fixation

•Generallyin strabismus oET = Nasal eccentric fixation oXT = temporal eccentric fixation •ParadoxicFixation oET with temporal eccentric fixation oXT with nasal eccentric fixation oCan see this after surgery

CN IV

•If there is a lesion in the CN IV nucleus, before the decussation: othe defect is contralateral •If there is a lesion at the site of the decussation: oThe defect is bilateral paresis •If there is after lesion decussation: oThe defect is ipsilateral. •Treatment oOcclusion oPrism •Start with ~ ½ the measured deviation in Primary gaze oTeach compensating head posture

CN VI

•Most prevalent non-comitantdeviation (acquired) oLong length of nerve and course oCongenital is rare •Some patients may look slightly esoin primary gaze •Complaints of horizontal diplopia •Some possible Causes oVascular oMS oTrauma oPseudotumor oTumor oAneurysm

Normal correspondence (NC)

•Objective Angle = 15 pdCRET •Angle of Anomaly = 0 = NC •Patient perceives perfect cross oDirectly measuring Angle A

Harmonious Anomalous correspondence (HAC)

•Objective Angle = 15 pdCRET •Angle of Anomaly = 15 pd(crossed fovealtag=eso) •Angle of Anomaly = Objective Angle = HAC

Normal correspondence (NC) w/ Eccentric Fixation

•Patient has a true objective angle = 20 pdCRXT •5 pdtemporal EF OD •Fovealtag is crossed 5 pd oTemporal EF: the vertical line is projected nasally •True angle of anomaly = A = 5 + -5 = 0 = NC A=0

Harmonious Anomalous correspondence (HAC) w/ Eccentric Fixation

•Patient has a trueobjective angle 15 pdCRET •Patient has 5 pdof nasal eccentric fixation •Fovealtag is crossed 10 pd •True angle of anomaly = 10 + 5 = 15 pd •Angle of Anomaly = Objective Angle = HAC

Hess-Lancaster test

•Patient sits at designated distance away from a screen oGenerally At 1 meter (1cm separation = 1 pd) •Patient wearing red/green glasses oStarting with red over right eye and green over the left •Doctor will hold red light and patient will hold green light oRight eye sees the red light (the eye that sees the doctors light is the fixating eye) •Examiner places their light in the 9 FOG and the patient will try to superimpose their light on top oWhen one eye field is plotted the patient will switch lights with the examiner OR the red/green lenses are switched around to plot the other eye field

Hering Bielshowsky Afterimage

•Patient will see with the fixating eye the horizontal AI at the red dot •Patient will have to tell you where the vertical AI is oMeasure the displacement with a cm ruler (if you do not have a grid)

Anomalous Correspondence

•Sensory mechanism against diplopia and confusion from strabismus oSensory system adapting to a motor problem •Binocular condition in which the primary visual direction of the deviated eye has shifted to a non-foveallocation (pseudo-fovea). •This non-fovealpoint now corresponds with the fovea of the fixating eye oAllows for some sensory integration

CN III

•Signs/Symptoms oDiplopia •If ptosis: may not oEOM •Any combination of elevation, depression or adduction deficit •Treatment oUnderlying cause oPrism oOcclusion