Assessing Comitancy Quiz
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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?

<p>Paretic (neurogenic) and mechanical restriction (myogenic).</p> Signup and view all the answers

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

<p>Trauma, vascular problems, neoplasm.</p> Signup and view all the answers

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

<p>Congenital, trauma, acute viral infection.</p> Signup and view all the answers

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

<p>Diplopia, discomfort.</p> Signup and view all the answers

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

<p>Maybe no complaints; head turn, tip or tilt may be noted.</p> 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?

<p>towards</p> Signup and view all the answers

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

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

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

<p>Lateral Rectus (LR), Medial Rectus (MR).</p> Signup and view all the answers

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

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

What symptom is a head tilt attempting to compensate for?

<p>Torsional and vertical diplopia.</p> Signup and view all the answers

What is a congenital torticollis?

<p>Sternocleidomastoid muscle fibrosis - tightened or shortened.</p> Signup and view all the answers

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

<p>Patch one eye.</p> Signup and view all the answers

A patient who has a congenital deviation is often diplopic.

<p>False</p> Signup and view all the answers

A patient who has an acquired deviation is often diplopic.

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

What would cause the underacting muscle itself to be paretic?

<p>Trauma.</p> Signup and view all the answers

What are the possible mechanical causes of underacting muscles?

<p>Faulty insertions, tendon abnormalities.</p> Signup and view all the answers

What are the possible innervational causes of underacting muscles?

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

What are the three causes of an overacting muscle?

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

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

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

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

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

What do you look out for when observing a patient?

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

What is the purpose of the Physiological H pattern?

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

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

<p>True</p> Signup and view all the answers

What is Hering's Law of Equal Innervation?

<p>Contralateral synergists are equally innervated.</p> 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?

<p>Because this is the eye that is normally fixating.</p> 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?

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

What is Sherrington's Law?

Signup and view all the answers

What is Version Testing?

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

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

<p>Overactivity (OA).</p> Signup and view all the answers

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

<p>Underactivity (UA).</p> Signup and view all the answers

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

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

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

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

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

<p>Forced Duction Testing.</p> Signup and view all the answers

How is Forced Duction Testing performed?

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

What does a positive Forced Duction Test indicate?

<p>Mechanical restriction.</p> 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?

<p>Right eye (RE).</p> Signup and view all the answers

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

<p>To the right.</p> Signup and view all the answers

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

<p>Right Lateral Rectus (RLR).</p> 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?

<p>Left Superior Oblique (LSO).</p> Signup and view all the answers

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

<p>Help confirm underacting muscle observed on version testing.</p> Signup and view all the answers

Uncrossed diplopia is (eso or exo)?

<p>Eso.</p> Signup and view all the answers

Crossed diplopia is (eso or exo)?

<p>Exo.</p> Signup and view all the answers

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

<p>Dot.</p> 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?

<p>Eye with the red filter.</p> Signup and view all the answers

Each square in testing represents how many PD?

<p>8 PD.</p> 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?

<p>UA Lateral Rectus (LR), OA Medial Rectus (MR).</p> 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?

<p>Identify affected muscle and determine magnitude of change in each field of gaze.</p> 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?

<p>Eye with the red filter.</p> 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?

<p>Eye wearing green filter.</p> Signup and view all the answers

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

<p>Green filter.</p> Signup and view all the answers

Green eye is (fixating light or testing light)?

<p>Fixating light.</p> Signup and view all the answers

Red eye is (fixating light or testing light)?

<p>Testing light.</p> Signup and view all the answers

Which eye muscle is UA and which is OA?

<p>Underacting: Right Superior Oblique (RSO), Overacting: Left Inferior Rectus (LIR).</p> 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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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.

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