CPOA Diagnostic Testing 3 — Questions and Answers
Question 1: Which test specifically evaluates a patient's sensitivity to contrast rather than high-contrast letter acuity?
- Contrast sensitivity testing (e.g., Pelli-Robson chart) (Correct answer)
- Snellen visual acuity chart
- Pinhole acuity test
- Potential acuity meter (PAM)
Correct answer: Contrast sensitivity testing (e.g., Pelli-Robson chart)
Contrast sensitivity testing, such as with the Pelli-Robson chart, evaluates how well patients detect differences in luminance, which can reveal visual deficits not shown on Snellen testing.
Question 2: The Amsler grid is used primarily to detect abnormalities in which area of the visual field?
- Central 20 degrees (macular area) (Correct answer)
- Far peripheral visual field
- Superior nasal visual field
- Temporal crescent
Correct answer: Central 20 degrees (macular area)
The Amsler grid tests the central 20 degrees of vision and is commonly used to detect metamorphopsia or scotomas from macular disease.
Question 3: During a slit lamp examination, the technique used to view the anterior chamber angle structures is called:
- Gonioscopy (Correct answer)
- Biomicroscopy
- Specular microscopy
- Pachymetry
Correct answer: Gonioscopy
Gonioscopy uses a special contact lens to redirect light and allow direct visualization of the trabecular meshwork and anterior chamber angle.
Question 4: A patient has a B-scan ultrasound ordered. This test is most useful when:
- The ocular media is opaque and the posterior segment cannot be directly viewed (Correct answer)
- Measuring corneal endothelial cell density
- Assessing tear film break-up time
- Evaluating pupil response to light
Correct answer: The ocular media is opaque and the posterior segment cannot be directly viewed
B-scan ultrasonography creates a cross-sectional image of the eye and is especially valuable when a dense cataract or vitreous hemorrhage prevents direct posterior segment examination.
Question 5: The Hirschberg light reflex test is used to estimate:
- The magnitude of a strabismic deviation (Correct answer)
- The degree of anisocoria
- The pupillary near response
- The corneal curvature
Correct answer: The magnitude of a strabismic deviation
The Hirschberg test estimates ocular alignment by noting the position of a penlight corneal reflex; each 1 mm of decentration equals approximately 15 prism diopters of deviation.
Question 6: In automated perimetry, a 'false positive' response occurs when:
- The patient presses the button when no stimulus was presented (Correct answer)
- The patient fails to respond to a bright stimulus
- The patient looks away from the fixation target
- The patient responds inconsistently to the same stimulus
Correct answer: The patient presses the button when no stimulus was presented
A false positive is recorded when the patient responds during a 'catch trial' with no stimulus, indicating trigger-happy behavior that reduces test reliability.
Question 7: Which dye is instilled in the eye to evaluate tear film quality and measure tear break-up time (TBUT)?
- Sodium fluorescein (Correct answer)
- Rose bengal
- Lissamine green
- Indocyanine green
Correct answer: Sodium fluorescein
Sodium fluorescein is used with cobalt blue illumination to measure the time for the tear film to break up after a blink, with a TBUT under 10 seconds suggesting dry eye.
CPOA Diagnostic Testing 3
Which test specifically evaluates a patient's sensitivity to contrast rather than high-contrast letter acuity?