AOC AOC Binocular Vision and Strabismus 1 — Questions and Answers
Question 1: Which term describes a manifest deviation of the eyes that is present without any occlusion?
- Heterophoria
- Heterotropia (Correct answer)
- Esophoria
- Exophoria
Correct answer: Heterotropia
A heterotropia is a manifest, constant or intermittent strabismus visible without covering either eye.
Question 2: The Hirschberg test estimates angle of strabismus by observing the position of which structure?
- Iris edge
- Corneal light reflex (Correct answer)
- Pupil margin
- Limbus
Correct answer: Corneal light reflex
The Hirschberg test uses the position of the corneal light reflex relative to the pupil center to estimate the angle of deviation.
Question 3: In the cover-uncover test, movement of the uncovered eye upon covering the other eye indicates which condition?
- Tropia (Correct answer)
- Phoria
- Amblyopia
- Nystagmus
Correct answer: Tropia
Movement of the uncovered eye during a cover-uncover test reveals a tropia (manifest strabismus).
Question 4: An esotropia where the angle is larger for near fixation than for distance is called which type?
- Basic esotropia
- Divergence excess esotropia
- Convergence excess esotropia (Correct answer)
- Divergence insufficiency esotropia
Correct answer: Convergence excess esotropia
Convergence excess esotropia presents with a significantly larger angle at near compared to distance fixation.
Question 5: Which prism test measures the full magnitude of a strabismic deviation including the motor fusion component?
- Krimsky test
- Prism cover test (Correct answer)
- Maddox rod test
- 4-diopter prism test
Correct answer: Prism cover test
The prism cover test dissociates fusion and measures the total deviation, including both manifest and latent components.
Question 6: Amblyopia secondary to strabismus is caused primarily by which mechanism?
- Retinal degeneration
- Cortical suppression of the deviating eye (Correct answer)
- Optic nerve atrophy
- Lens opacity
Correct answer: Cortical suppression of the deviating eye
The brain actively suppresses the image from the strabismic eye during the critical period, leading to reduced visual acuity.
AOC AOC Binocular Vision and Strabismus 1
Which term describes a manifest deviation of the eyes that is present without any occlusion?