CPOA Diagnostic Testing 5 — Questions and Answers
Question 1: When assessing stereopsis with the Randot or Titmus test, the patient must wear polarized glasses because:
- Each eye must see a slightly different image to simulate depth perception (Correct answer)
- The test requires the patient to see in 3D without glasses
- Polarized lenses neutralize the patient's refractive error
- The test measures color discrimination between eyes
Correct answer: Each eye must see a slightly different image to simulate depth perception
Polarized filters present slightly disparate images to each eye simultaneously, creating the retinal disparity needed to measure stereoscopic depth perception.
Question 2: The potential acuity meter (PAM) is used preoperatively to predict visual outcomes after cataract surgery by:
- Projecting a Snellen chart through a pinpoint of light directly onto the retina bypassing the cataract (Correct answer)
- Measuring macular function using electroretinography
- Assessing contrast sensitivity with a series of gratings
- Determining corneal clarity with specular reflection
Correct answer: Projecting a Snellen chart through a pinpoint of light directly onto the retina bypassing the cataract
The PAM projects a miniaturized acuity chart through an intact portion of the optical media onto the retina, allowing estimation of macular function independent of lens opacity.
Question 3: In a 24-2 visual field test, the '24' refers to:
- The test extends 24 degrees from fixation (Correct answer)
- 24 stimulus presentations per quadrant
- The test takes 24 minutes to complete
- 24 decibel maximum stimulus intensity
Correct answer: The test extends 24 degrees from fixation
The 24-2 pattern tests points within 24 degrees of fixation (plus two points beyond), making it sufficient to detect most glaucomatous defects while being faster than the 30-2 pattern.
Question 4: During keratometry, the 'mires' that the technician aligns are reflections of:
- The illuminated rings or targets reflected off the anterior corneal surface (Correct answer)
- Light from the retina passing through the cornea
- The slit beam projected onto the limbus
- Polarized light refracted through the crystalline lens
Correct answer: The illuminated rings or targets reflected off the anterior corneal surface
A keratometer measures the radius of curvature of the anterior cornea by analyzing the size and separation of illuminated mire reflections from the corneal surface.
Question 5: A patient undergoing visual evoked potential (VEP) testing has electrodes placed on their scalp to measure:
- Electrical responses in the visual cortex in response to visual stimuli (Correct answer)
- Electroretinographic responses from retinal photoreceptors
- Intraocular pressure fluctuations during the blink reflex
- Pupillary diameter changes in response to patterned stimuli
Correct answer: Electrical responses in the visual cortex in response to visual stimuli
VEP records cortical electrical activity from the occipital lobe in response to visual stimuli, helping evaluate the integrity of the visual pathway from retina to cortex.
Question 6: When using a Burton lamp (UV/black light) during a contact lens fitting, sodium fluorescein glows to show:
- The tear film pattern beneath the contact lens, revealing fitting characteristics (Correct answer)
- Areas of corneal neovascularization
- Presence of foreign bodies embedded in the conjunctiva
- Corneal endothelial cell density
Correct answer: The tear film pattern beneath the contact lens, revealing fitting characteristics
Under UV illumination, fluorescein pooling under a rigid lens appears bright green — thick pooling indicates lens clearance, while black (dark) areas indicate lens bearing.
Question 7: A dilatation log or record must be maintained that includes the drop used, concentration, time of instillation, and:
- The patient's signature of informed consent, initial pupil size, and the time the patient is cleared to drive (Correct answer)
- The patient's insurance information for billing the dilation procedure
- The name of the contact lens manufacturer if applicable
- The refraction results obtained before dilation
Correct answer: The patient's signature of informed consent, initial pupil size, and the time the patient is cleared to drive
Dilation records should document consent, baseline pupil assessment, medication details, and when the patient is safe to drive, ensuring both clinical and medicolegal requirements are met.
CPOA Diagnostic Testing 5
When assessing stereopsis with the Randot or Titmus test, the patient must wear polarized glasses because: