Ocular Motility Flashcards
Define versions.
Binocular conjugate eye movements
Both eyes move in the same direction
Dextroversion-right
Levoversion- left
Supra/infraversion- up and down
Define ductions.
Eye movement tested under monocular conditions
ADduction, AB, incyclo, Supra
Define incomitant strabismus.
Strabismus where angle of deviation varies with angle of gaze
Define comitant strabismus.
Strabismus where angle of deviation is independent of angle of gaze
Define paralysis, paresis, palsy, contracture.
Paralysis: complete loss of muscle function
Paresis: partial loss of muscle function
Palsy: partial or complete loss of nerve function
Contracture: inability of contracted muscle to relax fully
Define primary and secondary angle of deviation.
Primary angle of deviation: deviation when fixating with unaffected eye
Secondary angle of deviation: deviation when fixating with affected eye
Incomitant deviations may be due to:
Paresis due to trauma
Mechanical restriction
Innervational deficiencies (3, 4 and 6)
What is the innervation and primary movement of medial rectus?
3
Adduction
What is the innervation and primary movement for lateral rectus?
6
Abduction
What is the innervation and primary, secondary and tertiary movement for inferior rectus?
3
Depression
Excycloduction
Adduction
What is the innervation and primary, secondary and tertiary movement for superior rectus?
3
Elevation
Incycloduction
Adduction
What is the innervation and primary, secondary and tertiary movement for inferior oblique?
3
Excycloduction, elevation, abduction
What is the innervation and primary, secondary and tertiary movement for superior oblique?
4
Incycloduction
Depression
Abduction
What angle does the superior and inferior rectus make with the median plane? How can this be used to test the function of these muscles?
23 degrees
Abduct by 23 degrees elevate to test superior, depress to test inferior. This can indicate normal function or a problem with the muscle
What angle does the superior and inferior obliques make with the median plane?
55 degrees (51-55 for IO)
ADduct by 55 degrees depress for superior oblique, elevate for IO to test for normal function
How can we test medial and lateral recti?
Adduction and abduction
What is defined as the diagnostic action field (DAF)?
The direction in which you have to look in order to test the muscle
DAF for RSR is up and to the right
When is the deviation caused by the restricted muscle the greatest?
When you look towards the DAF
Describe Sherrington’s Law.
Contraction os a muscle is accompanied by simultaneous and proportional relaxation of its antagonist
SO contracts, IO relaxes
Describe herring’s law of equal innervation. What are contralateral synergists?
Contralateral synergist are equally innervated when a movement is executed by both eyes (extra innveration is sent to the abnormally functioning muscle, overaction of contralateral synergist)
Contralateral synergists are pairs of muscles with the same DAF (RSR and LIO up and right)
What are the secondary sequelae of a muscle restriction (RLR)?
Overaction of the contralateral synergist (LMR)
Contracture of the direct antagonist (RMR)
Secondary inhibitional palsy of the contralateral antagonist (LLR)
2 overacting (LMR, RMR)
2 underacting (RLR, LLR)
What are developmental anomalies contributing to the etiology of incomitant strabismus?
Aplasia (incomplete development)
Paradoxical or anomalous innervation
Musculo-facial anomalies:
Incomplete differentiation of muscle sheaths
Malinsertions
Defective muscle attachments
Defective muscle sheaths
Fibrotic muscles
What is the acquired etiology of incomitant strabismus?
Trauma affect nerve or muscle
Vascular lesions affecting nerve
Space occupying lesion
Infective
Demyelinating disease
Myasthenia gravis (fatigue)
Metabolic disorders (diabetes, thyroid)
Iatrogenic (surgery, retinal detachment)
What muscle are commonly affected by entrapment?
IO or IR
What are the most common causes of nerve palsy for patient under 25 years of age and over 50 years of age?
Under 25: MS, Tumor, infection/inflammation
Over 50: vascular disease, diabetes, tumor
What are the effects of internal carotid artery swelling?
Can press on 3, 4, 6
Life threatening if it bursts
What muscles within the superior orbital fissure are within the tendinous ring of Zinn? Outside?
Inside: superior and inferior 3, 6
Outside: 4
In a palsy in what direction so we experience binocular single vision? In what direction do we have abnormal head posture (AHP)?
Binocular single vision away form DAF
AHP patient turns eyes away from DAF but turns head TOWARDS DAF to maintain straight ahead vision
What are some common causes of abnormal head posture?
Abnormal neck muscles
Restricted visual field
Unilateral deafness
Shyness
Habit
Asymmetric hair style
Sending subliminal messages
What are characteristic of a total right 3 nerve palsy?
Eye is depressed (LH), abducted (exo), and intorted
ptosis
No binocular single vision
No AHP
What are commone causes of specific nerve palsies 3, 4, and 6?
3- aneurysm
4- trauma
6- tumor, trauma, vascular accident
When is a CT or MRI required for a ocular motility issue?
3 nerve palsy involving the pupil
Can be structural or compressive lesion such as tumor or aneurysm
Study slide 65 ocular motility
65
Define past pointing.
If patient is asked to point to object in DAF of the parotid muscle while normal eye is covered their finger will point past the object towards the DAF
Excess innvervation effects egocentric localization
How can we use the 9 positions of gaze to identify a deviation?
Quantify deviation in 9 positions of gaze using prism
Identify where the deviation is largest (DAF)
Use deviation (exo/eso) to identify which muscle of that DAF are deviated
What are the steps of the Parks-3-step test
Start with step 3, the affected muscle is a superior muscle on that side or an inferior muscle on the other side
Step 2, whatever the answer to step 2, the affected muscle is a rectus muscle on that side or an oblique on the other side
Step 1, the affected muscle is a depressor on that side or an elevator on the other side
- Superior
- Rectus
- Depressor
Describe a basic A-pattern.
Patient is more convergent (less divergent) on upgaze and more divergent on downgaze
4 exo
7 exo
11 exo
Describe a basic V pattern.
Patient is more convergent on downgaze and more divergent on upgaze
11 exo
7 exo
2 exo
Describe an also pattern.
A patient who is more convergent in upgaze with same deviation in primary and downgaze
4 exo
7 exo
7 exo
Describe an Aexo pattern.
Patient who is more divergent in downgaze, same deviation in primary and upgaze
7 exo
7 exo
11 exo
Describe a Veso pattern.
A patient who is more convergent in downgaze but has the same deviation in primary and upgaze
3 eso
3 eso
8 eso
Describe a Vexo pattern.
Patient who is more divergent in upgaze but has same deviation in primary and downgaze
11 exo
7 exo
7 exo
Describe the role of SR in AV patterns.
Overaction of SR will lead to A eso
Under action will produce V exo
Describe the role of IR in AV patterns.
Overactive IR- V eso
Under active IR- A exo
Describe the role of SO in AV patterns.
Overaction- A exo
Under action- V eso
Describe the role of IO in AV patterns.
Overaction- V exo
Under action- A eso
