COT Ocular Motility Testing 3 — Questions and Answers
Question 1: Which cranial nerve innervates the superior oblique muscle?
- CN III
- CN IV (Correct answer)
- CN V
- CN VI
Correct answer: CN IV
The trochlear nerve (cranial nerve IV) is the sole innervator of the superior oblique muscle.
Question 2: A Krimsky test uses prisms in which of the following ways?
- Over the fixing eye to center the light reflex in the deviating eye (Correct answer)
- Over the deviating eye to center the light reflex in the fixing eye
- Alternately over each eye to measure the total deviation
- Base-down over the higher eye to measure vertical deviation
Correct answer: Over the fixing eye to center the light reflex in the deviating eye
The Krimsky test places prism over the fixing eye until the corneal reflex centers in the deviating eye, neutralizing the deviation.
Question 3: When performing versions, which movement is described as both eyes rotating to the right?
- Dextroversion (Correct answer)
- Levoversion
- Supraversion
- Infraversion
Correct answer: Dextroversion
Dextroversion is a conjugate movement of both eyes to the right.
Question 4: Which test is most useful for detecting small vertical deviations and cyclotropia simultaneously?
- Hirschberg test
- Prism and alternate cover test
- Double Maddox rod test (Correct answer)
- Krimsky test
Correct answer: Double Maddox rod test
The double Maddox rod test is used to quantify cyclodeviation by having the patient align two perceived lines, one seen by each eye.
Question 5: Innervation of the inferior oblique muscle is supplied by which branch of the oculomotor nerve?
- Superior division
- Inferior division (Correct answer)
- Nasociliary branch
- Parasympathetic branch only
Correct answer: Inferior division
The inferior division of CN III innervates the inferior oblique, medial rectus, and inferior rectus muscles.
Question 6: A patient's left eye drifts up under cover during the cover-uncover test, and returns down when uncovered. This finding indicates:
- Left hypotropia
- Left hypertropia
- Left hyperphoria (Correct answer)
- Left hypophoria
Correct answer: Left hyperphoria
A latent upward drift of the left eye that corrects with fusion is called left hyperphoria (a phoria, not a tropia, since it requires cover to disrupt fusion).
Question 7: The Parks three-step test is specifically designed to identify which type of muscle palsy?
- Horizontal rectus muscle palsy
- Cyclovertical muscle palsy (Correct answer)
- Bilateral lateral rectus palsy
- Duane syndrome
Correct answer: Cyclovertical muscle palsy
The Parks three-step test systematically isolates which of the eight cyclovertical muscles is paretic by evaluating hyperdeviation in primary gaze, side gaze, and head tilt.
COT Ocular Motility Testing 3
Which cranial nerve innervates the superior oblique muscle?