Assessing Comitancy Quiz

Questions and Answers

What is a comitant deviation?

Angle of deviation is within 5∆ in all positions of gaze with either eye fixating.

What is a noncomitant deviation?

Angle of deviation changes in different fields of gaze and/or with either eye fixating.

What is more concerning, a recent onset non-comitancy or a longstanding non-comitancy?

Recent onset.

What are the two causes of non-comitant deviations?

Paretic (neurogenic) and mechanical restriction (myogenic). Signup and view all the answers

What are the three most common causes of noncomitant deviations in adults?

Trauma, vascular problems, neoplasm. Signup and view all the answers

What are the three most common causes of noncomitant deviations in children?

Congenital, trauma, acute viral infection. Signup and view all the answers

What symptoms/complaints do you expect in an adult patient with recent onset noncomitant deviations?

Diplopia, discomfort. Signup and view all the answers

What symptoms/complaints do you expect in a child with recent onset noncomitant deviation?

Maybe no complaints; head turn, tip or tilt may be noted. Signup and view all the answers

Patients will normally turn their head ___ (away from; towards) the paretic muscle to eliminate diplopia. What is this condition called?

towards Signup and view all the answers

Why would a patient turn their head away from the paretic muscle (happens rarely)?

Strive for suppression of one ocular image to eliminate diplopia. Signup and view all the answers

What muscles are possibly involved in a patient with a head turn?

Lateral Rectus (LR), Medial Rectus (MR). Signup and view all the answers

What muscles are possibly involved in head/chin elevation or depression?

Superior Oblique (SO), Inferior Oblique (IO), Superior Rectus (SR), Inferior Rectus (IR). Signup and view all the answers

What symptom is a head tilt attempting to compensate for?

Torsional and vertical diplopia. Signup and view all the answers

What is a congenital torticollis?

Sternocleidomastoid muscle fibrosis - tightened or shortened. Signup and view all the answers

What test can we do to tell the difference between Ocular and Congenital Torticollis?

Patch one eye. Signup and view all the answers

A patient who has a congenital deviation is often diplopic.

False Signup and view all the answers

A patient who has an acquired deviation is often diplopic.

True Signup and view all the answers

A patient who has a congenital deviation is often not aware of their abnormal head position.

True Signup and view all the answers

A patient who has an acquired deviation is often aware of their abnormal head position.

True Signup and view all the answers

What would cause the underacting muscle itself to be paretic?

Trauma. Signup and view all the answers

What are the possible mechanical causes of underacting muscles?

Faulty insertions, tendon abnormalities. Signup and view all the answers

What are the possible innervational causes of underacting muscles?

Impairment of cranial nerves (III, IV, VI). Signup and view all the answers

What are the three causes of an overacting muscle?

Mechanical (insertion, tendons), idiopathic, Hering's law of equal innervation. Signup and view all the answers

What are the objective tests we can use to evaluate Comitancy?

Observation, Version Testing, Duction Testing/Forced Duction Testing, Cover Test in all Diagnostic Fields of Gaze, Park's 3 Step. Signup and view all the answers

What are the subjective tests we can use to evaluate Comitancy?

Hess Lancaster Test, Maddox Rod Test, Red Lens Test, Double Maddox Rod Test. Signup and view all the answers

What do you look out for when observing a patient?

Head turn, tilt or tip; duration of anomalous head position; consistency of head orientation; and if closing one eye changes the position. Signup and view all the answers

What is the purpose of the Physiological H pattern?

Isolates muscles and muscle pairs; moves eyes into each Diagnostic Action Field (DAF). Signup and view all the answers

We use a double H to test primary up and downgaze for A and V patterns.

True Signup and view all the answers

What is Hering's Law of Equal Innervation?

Contralateral synergists are equally innervated. Signup and view all the answers

In a right lateral rectus (RLR) paresis, the primary deviation is when you have the left eye fixating. Why?

Because this is the eye that is normally fixating. Signup and view all the answers

In a right lateral rectus (RLR) paresis, the secondary deviation is what happens when you have the paretic eye fixating. What is a notable characteristic of this secondary deviation?

In a patient with a noncomitant or paretic muscle, the secondary deviation is much larger than the primary deviation. Signup and view all the answers

What is Sherrington's Law?

Signup and view all the answers

What is Version Testing?

Moving eyes binocularly into each Diagnostic Action Field, observing if the non-fixating eye lags under-act (UA) or excessive movement over-act (OA). Signup and view all the answers

When quantifying severity of a version test, what does a 4+ signify?

Overactivity (OA). Signup and view all the answers

When quantifying severity of a version test, what does a 4- signify?

Underactivity (UA). Signup and view all the answers

If we see an UA or OV after Version testing, what do we then do?

Duction testing, to see the extent of ocular motor limitation. Signup and view all the answers

If we see an UA after Duction testing, what should we ask?

If it's a severe innervational or mechanical anomaly. Signup and view all the answers

What test do we do to differentiate a severe innervational or mechanical cause of UA?

Forced Duction Testing. Signup and view all the answers

How is Forced Duction Testing performed?

Local anesthesia applied; eye grasped and moved in the direction opposite to that which mechanical restriction is suspected. Signup and view all the answers

What does a positive Forced Duction Test indicate?

Mechanical restriction. Signup and view all the answers

With which eye fixating is the Cover Test (CT) worse if its secondary deviation and the paretic eye fixating will have the greater CT?

Right eye (RE). Signup and view all the answers

In which field of gaze is the Cover Test (CT) largest?

To the right. Signup and view all the answers

What muscle is the UA muscle in the context of the Cover Test with the right eye fixating?

Right Lateral Rectus (RLR). Signup and view all the answers

In the context of the Cover Test with the left eye fixating, what is the muscle that is the UA muscle?

Left Superior Oblique (LSO). Signup and view all the answers

What is the purpose of the Maddox Rod/Red Lens Testing?

Help confirm underacting muscle observed on version testing. Signup and view all the answers

Uncrossed diplopia is (eso or exo)?

Eso. Signup and view all the answers

Crossed diplopia is (eso or exo)?

Exo. Signup and view all the answers

The Maddox rod is over the right eye so the left eye is seeing the (rod or dot)?

Dot. Signup and view all the answers

In the context of the Red lens test, which eye will see the laser if the lens is over the right eye?

Eye with the red filter. Signup and view all the answers

Each square in testing represents how many PD?

8 PD. Signup and view all the answers

In the context of visual field testing, which eye muscle is UA and which is OA in the enclosures?

UA Lateral Rectus (LR), OA Medial Rectus (MR). Signup and view all the answers

What are the Park's 3 Step Test questions?

<ol> <li>Which eye is hyper? 2. Is the hyper greater in right or left gaze? 3. Is the hyper greater in right or left tilt?</li> </ol> Signup and view all the answers

What is the point of the Hess Lancaster test?

Identify affected muscle and determine magnitude of change in each field of gaze. Signup and view all the answers

If you are wearing red/green glasses and you project a red laser, which eye will see the laser?

Eye with the red filter. Signup and view all the answers

If you are wearing red/green glasses and you project a green laser, which eye will see the laser?

Eye wearing green filter. Signup and view all the answers

Which filter will be able to see the grid with red print and white background?

Green filter. Signup and view all the answers

Green eye is (fixating light or testing light)?

Fixating light. Signup and view all the answers

Red eye is (fixating light or testing light)?

Testing light. Signup and view all the answers

Which eye muscle is UA and which is OA?

Underacting: Right Superior Oblique (RSO), Overacting: Left Inferior Rectus (LIR). Signup and view all the answers

Study Notes

Comitant vs. Non-Comitant Deviation

Comitant deviation: angle of deviation remains within 5∆ across all gaze positions.
Non-comitant deviation: angle of deviation varies with different gaze fields or eye fixation.

Clinical Significance

Recent onset non-comitant deviations can indicate life-threatening conditions.
Longstanding non-comitant deviations are generally less urgent.

Causes of Non-Comitant Deviations

Two primary causes:
- Paretic (neurogenic)
- Mechanical restriction (myogenic)
Most common causes in adults: trauma, vascular issues, neoplasms.
Most common causes in children: congenital factors, trauma, acute viral infections (tumor must be ruled out).

Symptoms and Patient Behavior

Adults with recent non-comitant deviations may experience diplopia and discomfort.
Children might not complain but may show head tilting or turning.

Head Position and Strabismus

Patients typically turn their head towards the paretic muscle to alleviate diplopia, a condition called ocular torticollis.
Rarely, some may turn away to suppress the double image.

Muscle Involvement

Significant muscles involved include lateral rectus (LR), medial rectus (MR), and vertically acting muscles (e.g., superior oblique (SO), inferior oblique (IO), superior rectus (SR), inferior rectus (IR)).

Torticollis

Congenital torticollis is caused by sternocleidomastoid muscle fibrosis.
Testing for torticollis involves patching one eye; head straightening indicates ocular torticollis, while remaining tilted suggests congenital causes.

Diplopia Awareness

Patients with congenital deviations are typically not aware of their abnormal head position and do not experience diplopia due to lifelong adaptation.
Those with acquired deviations are often aware of their head position and may experience diplopia.

Testing Procedures

Multiple tests can be employed to assess comitancy, including observation, version testing, duction testing, cover tests, and specific tests like Park's 3-step test.
Hering's Law: contralateral synergistic muscles are equally innervated during movements.

Forced Duction Testing

Used to differentiate between mechanical and innervational causes of underacting muscles.
A positive result indicates mechanical restriction.

Diplopia Types

Uncrossed diplopia corresponds to esotropia.
Crossed diplopia corresponds to exotropia.

Hess Lancaster Test Purpose

Identifies affected muscles and determines the magnitude of change in each gaze field.

Filters in Testing

The green filter is used for fixating light, while the red filter is utilized for testing light.
The enclosing squares in tests represent the underacting (UA) and overacting (OA) muscles, aiding in visual field analysis.

Severity and Measurement

Quantify the severity of manifestations during version testing with ratings indicating overaction (OA) or underaction (UA).
Each square in testing represents 8 prism diopters (PD) for calculation.

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Description

Test your understanding of comitant and noncomitant deviations in eye movement. This quiz covers definitions and the implications of recent versus longstanding non-comitancy. Perfect for students studying optometry or related fields.