7. Noncomitant Deviations - Clinical Binocular Vision Fall 2026

Comitant vs Noncomitant

Angle of deviation remains relatively constant across diagnostic fields of gaze

Comitant

Comitant vs Noncomitant

Angle of deviation changes across diagnostic fields of gaze

Noncomitant

Comitant vs Noncomitant

May have a difference between primary and secondary deviation

Noncomitant

Comitant vs Noncomitant

No meaningful difference between primary and secondary deviation

Comitant

Versions generally full/symmetric

Comitant

Versions may show overaction or underaction

Noncomitant

Think paretic, restrictive, mechanical, or innervational

Noncomitant

More commonly longstanding or developmental related

Comitant

Does changes in deviation on distance vs near CT indicate a noncomitant deviation?

No

How much change across gaze did we consider clinically significant?

>5 pd

What are the common causes of Noncomitant Deviations in adults?

-Trauma

-Vascular

-Neoplasm

What are the common causes of Noncomitant Deviations in children?

-Congenital

-Trauma

-Acute Viral Infection

Can adults have congenital non-comitant deviations?

Yes -- children grow up into adults with noncomitant congenital problems

The diagnostic evaluation of a deviation will depend on what factors?

-Age

-Time of onset

-Characteristics of the deviation (Myogenic, Neurogenic?)

Complete loss or impairment of the motor function

Paralysis or palsy

Affected with or pertaining to a paralysis

Paralytic

Slight or incomplete paralysis

Paresis

Pertaining to or affected with paresis

Paretic

Paretic vs Nonparetic

sudden onset

Paretic

Paretic vs Nonparetic

gradual onset

Nonparetic

Paretic vs Nonparetic

Age of onset = childhood

Nonparetic

Paretic vs Nonparetic

Age of onset = any age

paretic

Paretic vs Nonparetic

Hx of head trauma uncommon

Nonparetic

Paretic vs Nonparetic

Hx of head trauma common

Paretic

Paretic vs Nonparetic

Comitant deviation

nonparetic

Paretic vs Nonparetic

noncomitant deviation

Paretic

Paretic vs Nonparetic

Head posture is normal

Nonparetic

Paretic vs Nonparetic

Head posture is abnormal

paretic

Paretic vs Nonparetic

Diplopia uncommon

nonparetic

Paretic vs Nonparetic

Diplopia common

Paretic

Paretic vs Nonparetic

Neurological/systemic disease usually absent

nonparetic

Paretic vs Nonparetic

Neurological/systemic disease may be present

paretic

How can weakness of a paretic muscle become increasingly comitant over time?

1) Weakness of a paretic muscle

2) OA of the direct antagonist

3) Contrature of the direct antagonist

4) Deviation spreads into all DAFs

5) Becomes increasingly comitant

What is the effect of a noncomitant deviation (d/t paretic muscle) becoming increasingly comitant over time?

Deviation that used to look very different in different gazes will look increasingly similar over time

Characteristics of Recent Deviation

-(+) diplopia

-Noncomitant deviation

-No amblyopia present

-Marked abnormal head position

Characteristics of a Longstanding Deviation

-Usually no diplopia

-Comitancy may have spread

-May have slight anomalous head posture

-Old photos show anomalous head posture

-May have amblyopia

What is pattern strabismus?

A specific subtype of a non-comitant deviation

What patterns are typically associated with the term pattern strabismus?

A and V pattern

___% of strabs have an A or V pattern strabismus

30

When is a pattern strabismus seen?

-May be seen on versions

-Detected on ACT

What is the most common pattern strabismus?

V-eso

What is the least common pattern strabismus?

A-exo

X, Y, and λ patterns are ___

rare

In order to classify a deviation as A, V, X, Y, λ -- the deviation needs to be ____ pd difference in multiple gazes

5

What are the 2 major causes of pattern strabismus?

-Peripheral (Mechanical)

-Central (Neural)

What are some of the causes for peripheral (mechanical) pattern strabismus?

-Oblique muscle dysfunction

-Horizontal muscle dysfunction

-Cyclovertical muscle dysfunction

-Muscle pulley dysfunction

-Orbital abnormalities

What are some of the causes for central (neural) pattern strabismus?

-Loss of Fusion

-Supranuclear anomalies

-Vestibular anomalies

Describe an A Pattern Strabismus

-More Eso, Less Exo on Upgaze

-More Exo, Less Eso on Downgaze

Describe a V Pattern Strabismus

-More Exo, Less Eso on Upgaze

-More Eso, Less Exo on Downgaze

Which pattern will cause more symptoms for an Exo patient?

A pattern

**More exo at near. Patient is already Exo

Which pattern will cause more symptoms for an Eso patient?

V pattern

**More eso at near. Patient is already eso

Describe an X Pattern Strabismus

-More Exo, Less Eso on Upgaze

-No deviation in primary gaze

-More Exo, Less Eso on Downgaze

Describe an Y Pattern Strabismus

-More Exo, Less Eso on Upgaze

-No deviation in primary gaze

-No deviation in down gaze

Describe an λ Pattern Strabismus

-No deviation in upgaze

-No deviation in primary gaze

-More exo, less eso in downgaze

A-Pattern (Pic)

**More Eso in upgaze, Less eso in downgaze

A-Pattern (Pic)

How does an A pattern esotropia usually present?

Will present with chin elevation

Some cases of A pattern ET are d/t what?

overaction of the SO

A pattern XT are usually ______

symptomatic

**XT that is more exo in downgaze

A pattern XT usually presents how?

with chin depression

What is an A pattern XT usually d/t?

overaction of SO

V Pattern (Pic)

**more exo on upgaze; more eso on downgaze

V Pattern (Pic)

V Pattern ET are typically (asymptomatic/symptomatic)

symptomatic -- Eso that is more eso in downgaze

V Pattern ETs will typically have what presentation?

Chin depression to put eyes in upgaze

When a V pattern ET presents, what do you have to rule out?

Bilateral SO palsy

V Pattern XT will typically have what presentation?

Chin elevation to put eyes in downgaze

What are some cases of V pattern XT d/t?

Overaction of the IO

Y pattern is a ____ of V pattern

subtype

What is a Y pattern deviation?

Horizontal deviation remains stable from midline downgaze to primary position; relative divergence seen on upgaze

What is an A pattern deviation?

Horizontal deviation remains stable from the midline upgaze to primary position; relative divergence seen on downgaze

X Pattern (Pic)

X Pattern (Pic)

What is the effect of patients putting their chin down?

Putting eyes in upgaze

What is the effect of patients putting their chin up?

Putting their eyes in downgaze

What patients will likely want to put their chin down?

-Eyes in upgaze

-Eso with V pattern strabismus

-Exo with A pattern strabismus

What patients will likely want to put their chin up?

-Eyes in downgaze

-Exo with V pattern strabismus

-Eso with A pattern strabismus

Can EOM dysfunction be associated with pattern deviations?

Yes

Are EOM deviations synonymous with pattern strabismus?

No

What is the etiology of Oblique muscle Over/Under actions?

-Oblique dysfunction

-V Pattern

-A Pattern

When a V Pattern strabismus is present, what is the EOM dysfunction that could be present?

Underaction of the SO, Secondary overaction of the IO

When an A Pattern strabismus is present, what is the EOM dysfunction that could be present?

Underaction of the IO, Secondary overaction of the SO

In up gaze, what is the horizontal action of the IO?

Abduction

In down gaze, what is the horizontal action of the SO?

Abduction

If the oblique muscles are normal, what should you look at as the cause of a deviation?

horizontal and vertical muscles

Describe primary overaction of the inf oblique

Overelevation in Adduction

Primary Overaction of Inferior oblique will be (unilateral/bilateral)

can be either -- bilateral is more common

True or False:

Primary overaction of the inf oblique can be asymmetric when bilateral

true

In primary gaze, what is the deviation of an overacting inf oblique muscle?

Minimal to no deviation in primary gaze

Will there be a head tilt present with an IO overaction?

not in primary gaze

On version testing, what will be the presentation of an overacting inf oblique muscle?

-R hyper on L gaze

-L Hyper on R gaze

Is a primary inf oblique overaction associated with a SO palsy?

No

What is an inf oblique overaction associated with a SO palsy?

Secondary overacting inf oblique

What is a Secondary overacting inf oblique associated with?

Contralateral Sup rectus palsy

What is the cause of an overacting inf oblique muscle?

Unknown -- idiopathic

What is an overacting inf oblique muscle commonly associated with?

infantile ET

Is diplopia usually present with an overacting inf oblique muscle??

No

What are the DDx of an overacting inf oblique muscle?

-DVD

-Secondary overaction of IO d/t paretic SO

-Secondary overaction of IO d/t contralateral SR paresis

-Duane retraction syndrome

-Contralateral IR muscle restriction

-Skew Deviation

-Craniofacial syndromes

Over-Acting Inf Oblique Muscles (Pic)

**Os to the nose

Over-Acting Inf Oblique Muscles (Pic)

Over-Acting Inf Oblique Muscles (Pic)

Over-Acting Inf Oblique Muscles (Pic)

Superior oblique overaction presentation?

Over depression or downshoot o the adducted eye caused by the overaction of the superior oblique

Which is more common?

Overaction of SO or IO

Overaction of IO

What is the etiology of an overaction of the SO?

Unknown