ABO Low Vision & Rehabilitation 3 — Questions and Answers
Question 1: Which condition is characterized by a ring scotoma that most severely affects mobility and orientation rather than fine reading tasks in early stages?
- Age-related macular degeneration
- Retinitis pigmentosa (Correct answer)
- Diabetic macular edema
- Central serous chorioretinopathy
Correct answer: Retinitis pigmentosa
Retinitis pigmentosa causes progressive peripheral field loss (ring scotoma) that impairs mobility and night vision while central acuity for reading is preserved until late stages.
Question 2: The contrast sensitivity function (CSF) in low vision patients is clinically important because it
- Predicts intraocular pressure better than tonometry
- Often explains functional difficulty even when Snellen acuity appears relatively preserved (Correct answer)
- Measures the absolute scotoma size directly
- Is the primary predictor of refractive error progression
Correct answer: Often explains functional difficulty even when Snellen acuity appears relatively preserved
Patients can have near-normal Snellen acuity yet severely reduced contrast sensitivity, explaining difficulties with face recognition, mobility in low contrast environments, and reading low-contrast print.
Question 3: For a patient with hemianopia following a stroke, which non-optical rehabilitation strategy can most directly expand the usable visual field for reading?
- Fitting a Fresnel prism to shift images from the blind field
- Training compensatory saccadic eye movements toward the blind field side (Correct answer)
- Prescribing a high-plus reading add to magnify text
- Using yellow-tinted lenses to improve contrast
Correct answer: Training compensatory saccadic eye movements toward the blind field side
Saccadic training (scanning therapy) teaches patients to make larger, more deliberate eye movements into the blind field, effectively increasing the functional reading field.
Question 4: A low vision specialist is evaluating an 8-year-old with albinism and acuity of 20/200. Which device would be most appropriate as an initial near aid for classroom reading?
- A 20D handheld magnifier used monocularly
- A closed-circuit television (CCTV) system placed on the student's desk (Correct answer)
- A 4× stand magnifier
- Prescribed bifocal spectacles with high-plus adds
Correct answer: A closed-circuit television (CCTV) system placed on the student's desk
A CCTV (video magnifier) allows the child to use both hands, adjust magnification as needed, and work at a comfortable posture, making it practical for sustained classroom use.
Question 5: What is the primary advantage of a head-mounted electronic magnification device (e.g., OrCam, eSight) over optical magnifiers for patients with moderate low vision?
- They provide higher magnification than any optical system
- They allow hands-free use, variable magnification, and often have additional features like text-to-speech (Correct answer)
- They completely restore normal acuity to 20/20
- They are always covered by Medicare Part B
Correct answer: They allow hands-free use, variable magnification, and often have additional features like text-to-speech
Head-mounted electronic devices offer hands-free operation, adjustable magnification across tasks, and supplemental features such as OCR/text-to-speech that optical aids cannot provide.
Question 6: When counseling a low vision patient on lighting, the clinician recommends 'task lighting.' Which lamp type provides the most color-accurate rendering for reading and fine detail tasks?
- Incandescent bulbs (2700K)
- High color-rendering index (CRI ≥90) LED or fluorescent lamps (Correct answer)
- Standard cool-white fluorescent (CRI ~60)
- Sodium vapor lamps
Correct answer: High color-rendering index (CRI ≥90) LED or fluorescent lamps
High-CRI lamps render colors accurately, which improves contrast perception and reduces eye strain during prolonged reading or detail work.
Question 7: A patient with Stargardt disease has been referred for low vision rehabilitation. Which statement about this condition is most accurate for counseling purposes?
- It is an age-related condition unlikely to progress further after age 60
- It is an autosomal recessive inherited dystrophy causing progressive central vision loss typically beginning in childhood or young adulthood (Correct answer)
- It primarily affects peripheral vision and has no impact on reading
- It is caused by elevated intraocular pressure and can be treated with eye drops
Correct answer: It is an autosomal recessive inherited dystrophy causing progressive central vision loss typically beginning in childhood or young adulthood
Stargardt disease is the most common inherited macular dystrophy, autosomal recessive (ABCA4 mutation), causing central scotoma and progressive acuity loss usually before age 20.
ABO Low Vision & Rehabilitation 3
Which condition is characterized by a ring scotoma that most severely affects mobility and orientation rather than fine reading tasks in early stages?