AOC Amblyopia Management and Treatment 2 — Questions and Answers
Question 1: Eccentric fixation in amblyopia is defined as:
- The amblyopic eye habitually fixating with a retinal locus other than the fovea (Correct answer)
- Alternating fixation preference between the two eyes during distance viewing
- Inability to maintain steady fixation in either eye under monocular conditions
- Use of peripheral vision by the fellow eye to compensate for the amblyopic eye
Correct answer: The amblyopic eye habitually fixating with a retinal locus other than the fovea
Eccentric fixation occurs when the amblyopic eye consistently uses a non-foveal retinal point for fixation, indicating that the fovea has been suppressed and a parafoveal preferred retinal locus has developed.
Question 2: How does atropine penalization of the fellow eye treat amblyopia in a hyperopic child?
- It dilates the pupil of the amblyopic eye to increase retinal illumination
- It paralyzes accommodation in the fellow eye, blurring near vision and forcing use of the amblyopic eye (Correct answer)
- It directly stimulates visual cortex cells corresponding to the amblyopic eye
- It relaxes the ciliary muscle of the amblyopic eye to sharpen its retinal image
Correct answer: It paralyzes accommodation in the fellow eye, blurring near vision and forcing use of the amblyopic eye
Atropine instilled in the better-seeing eye inhibits accommodation, blurring near vision in that eye and compelling the child to rely on the amblyopic eye for near visual tasks, thereby stimulating its development.
Question 3: Why is deprivation amblyopia generally considered the most severe form?
- It is caused by inherited mutations affecting retinal photoreceptors
- Complete visual deprivation during the sensitive period eliminates patterned input, causing profound vision loss (Correct answer)
- It always involves both eyes simultaneously with equal severity
- It is uniquely resistant to atropine penalization therapy
Correct answer: Complete visual deprivation during the sensitive period eliminates patterned input, causing profound vision loss
Deprivation amblyopia results from complete blockage of patterned visual stimulation during the critical period (e.g., congenital cataract), leaving the visual cortex without the input needed for normal development and producing the most severe acuity loss.
Question 4: According to PEDIG classification, which best-corrected visual acuity range defines moderate amblyopia?
- 20/25 to 20/40
- 20/50 to 20/80 (Correct answer)
- 20/100 to 20/200
- Worse than 20/200
Correct answer: 20/50 to 20/80
The Pediatric Eye Disease Investigator Group classifies amblyopia severity as mild (20/25–20/40), moderate (20/50–20/80), and severe (20/100 or worse) based on best-corrected visual acuity in the amblyopic eye.
Question 5: PEDIG studies on patching for moderate amblyopia (approximately 20/80) found that prescribing how many hours of daily patching produced outcomes comparable to full-time occlusion?
- 1 hour per day
- 2 hours per day
- 6 hours per day (Correct answer)
- 10 hours per day
Correct answer: 6 hours per day
PEDIG randomized trials demonstrated that 6 hours of daily patching achieved visual acuity outcomes similar to full-time patching for moderate amblyopia while offering better compliance and fewer psychosocial challenges.
Question 6: What is the most common cause of deprivation amblyopia in infants?
- High bilateral refractive error left uncorrected in the first year
- Congenital or infantile cataract obstructing the visual axis (Correct answer)
- Large-angle infantile esotropia with dense suppression
- Severe unilateral ptosis without corneal exposure
Correct answer: Congenital or infantile cataract obstructing the visual axis
Congenital or infantile cataract is the leading cause of deprivation amblyopia because the lens opacity blocks all patterned visual input to the developing retina and visual cortex during the critical period.
Question 7: The CAM (Cambridge) vision stimulator was designed to treat amblyopia by:
- Occluding the fellow eye with a standardized translucent filter during near tasks
- Presenting rotating high-contrast sinusoidal gratings to stimulate cells in the amblyopic eye's visual cortex (Correct answer)
- Delivering pulsed-flash photostimulation to activate foveal photoreceptors
- Providing controlled binocular visual input to force cortical fusion cells to fire
Correct answer: Presenting rotating high-contrast sinusoidal gratings to stimulate cells in the amblyopic eye's visual cortex
The CAM stimulator presents rotating sinusoidal grating patterns of varying spatial frequencies to the amblyopic eye, theoretically activating spatial-frequency-tuned cortical cells that are underresponsive due to the amblyopia.
AOC Amblyopia Management and Treatment 2
Eccentric fixation in amblyopia is defined as: