CO Ocular Motility Evaluation & Binocular Vision Assessment 2 — Questions and Answers
Question 1: Which test best quantifies the angle of deviation in a patient who cannot fixate with either eye?
- Hirschberg test
- Krimsky test (Correct answer)
- Maddox rod test
- Four-prism diopter base-out test
Correct answer: Krimsky test
The Krimsky test uses prisms over the deviating eye to center the corneal light reflex, estimating the angle when fixation is poor.
Question 2: During the cover-uncover test, the covered eye moves outward when uncovered. This indicates:
- Esotropia (Correct answer)
- Exotropia
- Hypertropia
- Hypotropia
Correct answer: Esotropia
An outward refixation movement on uncovering means the eye was deviated inward (esotropia) under the cover.
Question 3: Which cyclovertical muscle is tested by asking the patient to look down and in?
- Superior oblique (Correct answer)
- Inferior oblique
- Superior rectus
- Inferior rectus
Correct answer: Superior oblique
The superior oblique's primary depressor action is greatest when the eye is adducted, so looking down and in isolates it.
Question 4: A patient with a positive Worth 4-dot test showing 5 lights at near but fusion at distance most likely has:
- Monofixation syndrome
- Alternating exotropia
- Intermittent exotropia with divergence excess (Correct answer)
- Consecutive esotropia
Correct answer: Intermittent exotropia with divergence excess
Intermittent exotropia with divergence excess pattern shows fusion at near (smaller deviation) but suppression/diplopia at distance (larger deviation).
Question 5: The Maddox rod test dissociates the eyes by:
- Occluding one eye with an opaque paddle
- Converting a point light source into a streak seen only by one eye (Correct answer)
- Introducing a vertical prism before one eye
- Polarizing light differently for each eye
Correct answer: Converting a point light source into a streak seen only by one eye
The grooved glass converts the white dot of light into a red streak, preventing fusion and revealing the phoria.
Question 6: Parks three-step test is used to identify which type of muscle palsy?
- Horizontal rectus palsy
- Cyclovertical muscle palsy (Correct answer)
- Bilateral superior oblique palsy
- Internuclear ophthalmoplegia
Correct answer: Cyclovertical muscle palsy
The three-step test (hypertropia, gaze position, and Bielschowsky head tilt) systematically isolates a single weak cyclovertical muscle.
Question 7: A negative stereoacuity on the Randot test with normal Worth 4-dot fusion most likely represents:
- Monofixation syndrome (Correct answer)
- Total suppression of one eye
- Anomalous retinal correspondence
- Normal binocular vision
Correct answer: Monofixation syndrome
Monofixation syndrome produces peripheral fusion (positive W4D) but absent or severely reduced central stereopsis.
CO Ocular Motility Evaluation & Binocular Vision Assessment 2
Which test best quantifies the angle of deviation in a patient who cannot fixate with either eye?