AOC AOC Binocular Vision and Strabismus 2 — Questions and Answers
Question 1: Which type of strabismus is characterized by outward deviation of one or both eyes?
- Esotropia
- Hypertropia
- Exotropia (Correct answer)
- Cyclotropia
Correct answer: Exotropia
Exotropia refers to a manifest outward (divergent) deviation of one or both eyes.
Question 2: The alternate cover test primarily measures which type of deviation?
- Manifest deviation only
- Latent deviation only
- Total deviation including phoria and tropia (Correct answer)
- Cyclodeviations only
Correct answer: Total deviation including phoria and tropia
By alternately covering each eye and dissociating fusion, the alternate cover test reveals the total deviation (tropia plus phoria).
Question 3: Which surgical procedure on an extraocular muscle increases its effective length, thereby weakening its action?
- Resection
- Tucking
- Recession (Correct answer)
- Advancement
Correct answer: Recession
A recession moves the muscle insertion posteriorly, lengthening its effective moment arm and reducing its pulling force.
Question 4: The Krimsky test estimates angle of deviation using which technique?
- Placing prism before the deviating eye until corneal reflexes are symmetric (Correct answer)
- Measuring the subjective diplopia angle
- Performing alternate cover with prisms
- Using a synoptophore
Correct answer: Placing prism before the deviating eye until corneal reflexes are symmetric
The Krimsky test places prisms before the deviating eye until the corneal light reflex is centered, providing an estimate of deviation.
Question 5: Stereopsis testing such as the Randot or Titmus fly test evaluates which visual function?
- Color vision
- Contrast sensitivity
- Binocular depth perception (Correct answer)
- Peripheral visual field
Correct answer: Binocular depth perception
Stereopsis tests measure binocular depth perception by presenting slightly disparate images to each eye requiring fusion.
Question 6: Dissociated vertical deviation (DVD) is characterized by which finding?
- Constant hypertropia of the fixating eye
- Upward drift of the non-fixating eye when it is occluded or inattentive (Correct answer)
- Bilateral horizontal tropia
- Fixed vertical deviation measured by prism cover test
Correct answer: Upward drift of the non-fixating eye when it is occluded or inattentive
DVD presents as an upward slow drift of the non-fixating or occluded eye that is not explainable by a simple hypertropia.
AOC AOC Binocular Vision and Strabismus 2
Which type of strabismus is characterized by outward deviation of one or both eyes?