CO Diagnosis & Management of Strabismus and Amblyopia 2 — Questions and Answers
Question 1: A 4-year-old has 20/200 vision in the left eye with no structural abnormality. Best initial treatment after refractive correction is:
- Patching the amblyopic eye
- Patching the fellow (sound) eye (Correct answer)
- Atropine penalization of the amblyopic eye
- Surgery to correct any strabismus first
Correct answer: Patching the fellow (sound) eye
Occlusion therapy for amblyopia involves patching the sound (fellow) eye to force use of the amblyopic eye.
Question 2: Which of the following best describes anisometropic amblyopia?
- Amblyopia caused by equal high refractive error in both eyes
- Amblyopia resulting from unequal refractive error between the two eyes (Correct answer)
- Amblyopia due to strabismus alone
- Amblyopia from lid ptosis blocking the visual axis
Correct answer: Amblyopia resulting from unequal refractive error between the two eyes
Anisometropic amblyopia results from a significant difference in refractive error between the two eyes, causing chronic blur in one eye.
Question 3: The Krimsky test is used to measure:
- Accommodative convergence/accommodation ratio
- Angle of deviation using prisms and the corneal light reflex (Correct answer)
- Stereoacuity at near
- Fusional vergence amplitudes
Correct answer: Angle of deviation using prisms and the corneal light reflex
The Krimsky test measures the angle of strabismus by centering the corneal light reflex with a prism placed over the deviating eye.
Question 4: A child with esotropia shows a larger deviation on alternate prism cover test than on simultaneous prism cover test. This finding is most consistent with:
- Paralytic strabismus
- Monofixation syndrome (Correct answer)
- Consecutive exotropia
- Microtropia
Correct answer: Monofixation syndrome
In monofixation syndrome, the APCT reveals a larger deviation because it breaks down any peripheral fusion, unmasking the full angle.
Question 5: In intermittent exotropia, the deviation is typically best controlled:
- At distance fixation
- At near fixation (Correct answer)
- During monocular viewing
- Under bright lighting conditions
Correct answer: At near fixation
Near fusion is usually stronger than distance fusion in intermittent exotropia, so the deviation is better controlled at near.
Question 6: Atropine penalization for amblyopia works by:
- Stimulating the amblyopic eye directly
- Blurring near vision in the sound eye to promote use of the amblyopic eye (Correct answer)
- Dilating the amblyopic eye to improve retinal sensitivity
- Correcting accommodative esotropia
Correct answer: Blurring near vision in the sound eye to promote use of the amblyopic eye
Atropine cyclopleges the sound eye, blurring near vision and forcing the child to use the amblyopic eye for close tasks.
Question 7: Which measurement is critical when planning strabismus surgery for an incomitant deviation?
- Stereoacuity in primary gaze only
- Deviation measurements in all nine diagnostic positions of gaze (Correct answer)
- Cover test results at near only
- Color vision testing
Correct answer: Deviation measurements in all nine diagnostic positions of gaze
Incomitant deviations vary by gaze position, so measurements in all nine positions are needed to plan appropriate muscle surgery.
CO Diagnosis & Management of Strabismus and Amblyopia 2
A 4-year-old has 20/200 vision in the left eye with no structural abnormality.
Best initial treatment after refractive correction is: