Comitancy Testing - Clinical Binocular Vision Fall 2026

What is a COMITANT deviation?

-Within 5PD for lateral deviations

-Within 5PD for vertical deviations

What is the PD amount a deviation can differ to be considered a COMITANT deviation?

true

True or False:

Some practitioners only consider deviations

What is a NONCOMITANT deviation?

->5PD (lateral/horizontal) deviations

>>5PD vertical deviations

What is the PD amount a deviation will differ to be considered a NONCOMITANT deviation?

False -- this is d/t the AC/A ratio

True or False:

If a deviation is NOT THE SAME at distance and near this is considered a non-comitant deviation

a health or life threatening situation

Recent onset non-comitancy can represent what?

true

True or False:

Recent onset non-comitant deviations may require immediate referral

treatment and prognosis

Identifying the characteristics of a longstanding deviation can help with what?

-obstetric trauma

-idiopathic (mostly)

-CNS dysfunction

-Muscle anomalies

-Trauma

-vascular disease (older patients)

-neoplasm

-viral disease (younger patients)

-chronic disease

What are common etiologies of non-comitant deviations?

-Paretic

-Mechanical Restriction

What are common subsets of non-comitant deviations?

Neurological or innervational

What is a PARETIC non-comitant deviation?

-abnormal muscles

-structural restriction

What are MECHANICAL RESTRICTIONS that can lead to non-comitant deviations?

1) Microvascular disease

2) Trauma

3) Neoplasm

What are the 3 most common causes for ADULT non-comitant deviations?

1) Congenital/developmental abnormalities

2) Trauma

3) Neoplasm

4) Infection/Inflammation

What are the 3 most common causes for PEDIATRIC non-comitant deviations?

-recent onset diplopia

-discomfort

What are common symptoms of recent onset non-comitant deviations in ADULTS?

-No complaints possible

-Head turn, tip, tilt can be noted

What are common symptoms of recent onset non-comitant deviations in CHILDREN?

towards

Usually, patients with a non-comitant deviation will turn their head (Towards/away from) the field of action of the paretic muscle

In order to eliminate diplopia and put the fixating eye in the most comfortable position

Why do patients turn their heads towards the field of action of the paretic muscle?

Abnormal head posture d/t disorders of the visual pathway or another ocular cause

What is OCULAR TORTICOLLIS?

true

True or False:

If a child presents with a head turn or tilt, you need to assume a non-comitant deviation is present until proven otherwise

Yes -- very rare but sometimes patients do this to make diplopia worse. They can then ignore one of the images

Is it possible for a patient to turn their head AWAY from the paretic muscle?

Medial or lateral rectus palsy

If a head turn is present, what is the likely etiology for this abnormal head posture?

-Vertically acting muscle palsy

-A/V pattern

-Torsional and vertical diplopia combined

If a head tilt/chin tilt is present, what is the likely etiology for this abnormal head posture?

-Congenital/Nonocular Torticollis

-Ocular Torticollis

What are the 2 forms of torticollis that were mentioned in this module?

Sternocleidomastoid muscle fibrosis with tightened or shortened muscle

What is Congenital/Nonocular Torticollis due to?

Noncomitant deviation, often cyclovertical

What is Ocular Torticollis due to?

Patch test

How to differentiate ocular vs congenital/nonocular torticollis from each other?

You will patch one eye of a patient w/ torticollis. If the patient remains tilted with the patch on, this is indicative of congenital torticollis. If the patient straightens their head with the patch in place, this is indicative of ocular torticollis.

What is the patch test? What do the results of this test predict?

Birth or soon after

Congenital vs Acquired Torticollis

Age of onset of congenital torticollis

Rarely

Congenital vs Acquired Torticollis

Age of onset of acquired torticollis

Difficulty straightening the head

Congenital vs Acquired Torticollis

Head position of congenital torticollis

Head is easily straightened

Congenital vs Acquired Torticollis

Age of onset of acquired torticollis

Hardening

Congenital vs Acquired Torticollis

Neck muscle appearance with congenital torticollis

(-) w/ palpation

Congenital vs Acquired Torticollis

Neck muscle appearance with acquired torticollis

No diplopia

Congenital vs Acquired Torticollis

Vision with congenital torticollis

Vertical deviation possible, frequent diplopia if head is straight

Congenital vs Acquired Torticollis

Vision with acquired torticollis

No change in head position

Congenital vs Acquired Torticollis

Occlusion test result of congenital torticollis

Head will straighten

Congenital vs Acquired Torticollis

Occlusion test result of acquired torticollisq

infrequent (unless decompensated)

Congenital vs Acquired Non-Comitant Deviations

Diplopia with congenital non-comitant deviation

Abnormal head posture present, patient unaware

Congenital vs Acquired Non-Comitant Deviations

Head posture with congenital non-comitant deviation

-No difference w/ paretic cause

-With Mechanical cause a difference is present

Congenital vs Acquired Non-Comitant Deviations

Is there a difference between primary and secondary deviation with a congenital non-comitant deviation?

Maybe

Congenital vs Acquired Non-Comitant Deviations

Is amblyopia present with congenital non-comitant deviation

Maybe

Congenital vs Acquired Non-Comitant Deviations

Is suppression present with congenital non-comitant deviation

-Paretic cause = not severe

-Mechanical cause = marked limitation in motility

Congenital vs Acquired Non-Comitant Deviations

What is the ocular motility with congenital non-comitant deviation?

Rarely

Congenital vs Acquired Non-Comitant Deviations

Is there a neurological/systemic disease cause for congenital non-comitant deviations?

frequently present (greater in one field of gaze)

Congenital vs Acquired Non-Comitant Deviations

Diplopia with acquired non-comitant deviation

Usually no abnormal head posture; may have this to eliminate diplopia

Congenital vs Acquired Non-Comitant Deviations

Head posture with acquired non-comitant deviation

Present

Congenital vs Acquired Non-Comitant Deviations

Is there a difference between primary and secondary deviation with a acquired non-comitant deviation?

No

Congenital vs Acquired Non-Comitant Deviations

Is amblyopia present with acquired non-comitant deviation

No

Congenital vs Acquired Non-Comitant Deviations

Is suppression present with acquired non-comitant deviation

Severe limitations in ocular motility

Congenital vs Acquired Non-Comitant Deviations

What is the ocular motility with acquired non-comitant deviation?

frequently

Congenital vs Acquired Non-Comitant Deviations

Is there a neurological/systemic disease cause for acquired non-comitant deviations?

-The underacting muscle

-Determine if the muscle is paretic

If a deviation is found to be non-comitant, what do we have to identify?

Recent onset?

If a non-comitant deviation is found to have a paretic muscle, what do we have to figure out next?

1) Trauma

2) Mechanical

3) Innervational

What are the 3 common causes for UNDERACTING muscles?

Direct injury/weakness of a muscle

Describe how trauma can be the cause of an underacting muscle

-Faulty insertions

-Tendon abnormalities

-Adjacent structure abnormalities

Describe how the cause of an underacting muscle could be mechanical?

Impairment of the CNs

Describe how the cause of an underacting muscle could be innervational?

1) Mechanical

2) Idiopathic

3) Hering's Law

What are the 3 common causes for OVERACTING muscles?

-Faulty muscle insertions

-Tendon abnormalities

Describe how the cause of an overacting muscle could be mechanical?

-Observation

-Version Testing

-Duction Testing/Forced Duction Test

-Cover Test in all Diagnostic Fields of Gaze

-Park's 3 Step

Objective Testing for Comitancy

-Red Lens Test

-Maddox Rod Test

-Hess Lancaster Test

-Double Maddox Rod Test

Subjective Testing for Comitancy

-Head turn, tilt, tip

-How long has the patient had anomalous head posture?

-Is the head always tilted/turned/tipped the same way?

-Closing or covering an eye

What observations can be made to make the assumption that a non-comitant deviation is present?

-Versions

-Ductions

-Forced Duction Testing

What are the tests for ocular motility that we can perform?

binocular

Versions are (monocular/binocular)

monocular

Ductions are (monocular/binocular)

SR, IR, MR, IO

CN III innervates which oculomotor nerves?

SO

CN IV innervates which oculomotor nerves?

LR

CN VI innervates which oculomotor nerves?

Primary: Abduction

EOM ACTIONS

LR

Primary: Adduction

EOM ACTIONS

MR

-Primary: Depression

-Secondary: Excyclotorsion

-Tertiary: Adduction

EOM ACTIONS

IR

-Primary: Elevation

-Secondary: Incyclotorsion

-Tertiary: Adduction

EOM ACTIONS

SR

-Primary: Excyclotorsion

-Secondary: Elevation

-Tertiary: Abduction

EOM ACTIONS

IO

-Primary: Incyclotorsion

-Secondary: Depression

-Tertiary: Abduction

EOM ACTIONS

SO

23

The recti muscles will form a ____º angle between the visual axis and the line of insertion

in front of the equator

Where are the recti inserted into the globe relative to the equator?

51

The oblique muscles will form a ____º angle between the visual axis and the line of insertion

behind the equator

Where are the oblique muscles inserted into the globe relative to the equator?

Yes -- Broad H test

Can we isolate individual actions of the EOMs?

Isolating Actions of Muscles w/ Broad H Test (Pic)

Isolating Actions of Muscles w/ Broad H Test (Pic)

Isolates muscles and muscle pairs

What is the function of the physiological H pattern?

Into each of their diagnostic action fields

Where does the physiological H pattern move the eyes?

A and V patterns

When testing primary up and downgaze on the Broad H test, what is this testing?

Contralateral synergists are equally innervated

What is Hering's Law of Equal Innervation?

RMR and LLR

What is the YOKED muscle pair that will move the eyes into L gaze?

Hering's Law of Equal Innervation -- LLR Paresis (Pic)

Hering's Law of Equal Innervation -- LLR Paresis (Pic)

R eye is fixating (L eye is paretic)

When there is a LLR paresis found on Broad H Test, how do we test the primary angle of deviation?

L eye is fixating (L eye is paretic)

When there is a LLR paresis found on Broad H Test, how do we test the secondary angle of deviation?

There will be an overaction of the RMR

What will we likely find when there is a LLR palsy and the L eye is fixating?

Contraction of a muscle is accompanied by a simultaneous and proportional relaxation of its antagonist

What is Sherington's Law?

-Agonist: RMR, LLR

-Antagonist: RLR, LMR

When the eyes move into L gaze, what are the agonist/antagonist muscles that are innervated?

uncorrected

A patient should be (corrected/uncorrected) for version testing

moves eyes binocularly into each diagnostic action field

What is the function of version testing?

If non-fixating eye lags (UA) or excessive movement (OA)

What should be observed on version testing?

Version Testing (Pic)

Version Testing (Pic)

Hirshberg

You can add _____ to version testing to increase sensitivity

-Move the penlight and yourself into every DAF

-Can help make ocular misalignment/asymmetry more apparent

How to add Hirshberg testing to version testing?

Versions (Pic)

Versions (Pic)