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Questions and Answers
What is a comitant deviation?
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?
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?
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?
What are the two causes of non-comitant deviations?
What are the three most common causes of noncomitant deviations in adults?
What are the three most common causes of noncomitant deviations in adults?
What are the three most common causes of noncomitant deviations in children?
What are the three most common causes of noncomitant deviations in children?
What symptoms/complaints do you expect in an adult patient with recent onset noncomitant deviations?
What symptoms/complaints do you expect in an adult patient with recent onset noncomitant deviations?
What symptoms/complaints do you expect in a child with recent onset noncomitant deviation?
What symptoms/complaints do you expect in a child with recent onset noncomitant deviation?
Patients will normally turn their head ___ (away from; towards) the paretic muscle to eliminate diplopia. What is this condition called?
Patients will normally turn their head ___ (away from; towards) the paretic muscle to eliminate diplopia. What is this condition called?
Why would a patient turn their head away from the paretic muscle (happens rarely)?
Why would a patient turn their head away from the paretic muscle (happens rarely)?
What muscles are possibly involved in a patient with a head turn?
What muscles are possibly involved in a patient with a head turn?
What muscles are possibly involved in head/chin elevation or depression?
What muscles are possibly involved in head/chin elevation or depression?
What symptom is a head tilt attempting to compensate for?
What symptom is a head tilt attempting to compensate for?
What is a congenital torticollis?
What is a congenital torticollis?
What test can we do to tell the difference between Ocular and Congenital Torticollis?
What test can we do to tell the difference between Ocular and Congenital Torticollis?
A patient who has a congenital deviation is often diplopic.
A patient who has a congenital deviation is often diplopic.
A patient who has an acquired deviation is often diplopic.
A patient who has an acquired deviation is often diplopic.
A patient who has a congenital deviation is often not aware of their abnormal head position.
A patient who has a congenital deviation is often not aware of their abnormal head position.
A patient who has an acquired deviation is often aware of their abnormal head position.
A patient who has an acquired deviation is often aware of their abnormal head position.
What would cause the underacting muscle itself to be paretic?
What would cause the underacting muscle itself to be paretic?
What are the possible mechanical causes of underacting muscles?
What are the possible mechanical causes of underacting muscles?
What are the possible innervational causes of underacting muscles?
What are the possible innervational causes of underacting muscles?
What are the three causes of an overacting muscle?
What are the three causes of an overacting muscle?
What are the objective tests we can use to evaluate Comitancy?
What are the objective tests we can use to evaluate Comitancy?
What are the subjective tests we can use to evaluate Comitancy?
What are the subjective tests we can use to evaluate Comitancy?
What do you look out for when observing a patient?
What do you look out for when observing a patient?
What is the purpose of the Physiological H pattern?
What is the purpose of the Physiological H pattern?
We use a double H to test primary up and downgaze for A and V patterns.
We use a double H to test primary up and downgaze for A and V patterns.
What is Hering's Law of Equal Innervation?
What is Hering's Law of Equal Innervation?
In a right lateral rectus (RLR) paresis, the primary deviation is when you have the left eye fixating. Why?
In a right lateral rectus (RLR) paresis, the primary deviation is when you have the left eye fixating. Why?
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 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?
What is Sherrington's Law?
What is Sherrington's Law?
What is Version Testing?
What is Version Testing?
When quantifying severity of a version test, what does a 4+ signify?
When quantifying severity of a version test, what does a 4+ signify?
When quantifying severity of a version test, what does a 4- signify?
When quantifying severity of a version test, what does a 4- signify?
If we see an UA or OV after Version testing, what do we then do?
If we see an UA or OV after Version testing, what do we then do?
If we see an UA after Duction testing, what should we ask?
If we see an UA after Duction testing, what should we ask?
What test do we do to differentiate a severe innervational or mechanical cause of UA?
What test do we do to differentiate a severe innervational or mechanical cause of UA?
How is Forced Duction Testing performed?
How is Forced Duction Testing performed?
What does a positive Forced Duction Test indicate?
What does a positive Forced Duction Test indicate?
With which eye fixating is the Cover Test (CT) worse if its secondary deviation and the paretic eye fixating will have the greater CT?
With which eye fixating is the Cover Test (CT) worse if its secondary deviation and the paretic eye fixating will have the greater CT?
In which field of gaze is the Cover Test (CT) largest?
In which field of gaze is the Cover Test (CT) largest?
What muscle is the UA muscle in the context of the Cover Test with the right eye fixating?
What muscle is the UA muscle in the context of the Cover Test with the right eye fixating?
In the context of the Cover Test with the left eye fixating, what is the muscle that is the UA muscle?
In the context of the Cover Test with the left eye fixating, what is the muscle that is the UA muscle?
What is the purpose of the Maddox Rod/Red Lens Testing?
What is the purpose of the Maddox Rod/Red Lens Testing?
Uncrossed diplopia is (eso or exo)?
Uncrossed diplopia is (eso or exo)?
Crossed diplopia is (eso or exo)?
Crossed diplopia is (eso or exo)?
The Maddox rod is over the right eye so the left eye is seeing the (rod or dot)?
The Maddox rod is over the right eye so the left eye is seeing the (rod or dot)?
In the context of the Red lens test, which eye will see the laser if the lens is over the right eye?
In the context of the Red lens test, which eye will see the laser if the lens is over the right eye?
Each square in testing represents how many PD?
Each square in testing represents how many PD?
In the context of visual field testing, which eye muscle is UA and which is OA in the enclosures?
In the context of visual field testing, which eye muscle is UA and which is OA in the enclosures?
What are the Park's 3 Step Test questions?
What are the Park's 3 Step Test questions?
What is the point of the Hess Lancaster test?
What is the point of the Hess Lancaster test?
If you are wearing red/green glasses and you project a red laser, which eye will see the laser?
If you are wearing red/green glasses and you project a red laser, which eye will see the laser?
If you are wearing red/green glasses and you project a green laser, which eye will see the laser?
If you are wearing red/green glasses and you project a green laser, which eye will see the laser?
Which filter will be able to see the grid with red print and white background?
Which filter will be able to see the grid with red print and white background?
Green eye is (fixating light or testing light)?
Green eye is (fixating light or testing light)?
Red eye is (fixating light or testing light)?
Red eye is (fixating light or testing light)?
Which eye muscle is UA and which is OA?
Which eye muscle is UA and which is OA?
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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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