ABO NOCE Basic Opticianry Optical Instrumentation Use Questions and Answers 3 — Questions and Answers
Question 1: When using a pupillometer to measure monocular PDs, what is the correct patient fixation target?
- The examiner's left eye for both measurements
- The instrument's internal fixation light for each eye separately (Correct answer)
- A distant object on the wall
- The examiner's nose bridge
Correct answer: The instrument's internal fixation light for each eye separately
The patient fixates on the internal fixation light while each eye is measured separately to obtain accurate monocular PDs.
Question 2: Which of the following best describes the function of a frame warmer (frame heater)?
- It sterilizes frames before fitting
- It softens plastic frames for adjustment without cracking (Correct answer)
- It measures the bridge size of frames
- It stretches metal frames to fit larger faces
Correct answer: It softens plastic frames for adjustment without cracking
A frame warmer uses heat (salt pan, hot air, or infrared) to soften plastic acetate frames so they can be safely adjusted without cracking.
Question 3: An auto-lensometer differs from a manual lensometer primarily in that it:
- Cannot measure prism
- Automatically determines sphere, cylinder, axis, and prism without manual wheel adjustments (Correct answer)
- Only measures single vision lenses
- Requires the patient to be present
Correct answer: Automatically determines sphere, cylinder, axis, and prism without manual wheel adjustments
An auto-lensometer (focimeter) electronically measures and displays all lens parameters automatically when the lens is placed on the lens stop.
Question 4: When verifying lenses with a lensometer, the cylinder power of a –2.00 –1.50 × 090 lens is measured by:
- Reading only when all target lines are clear simultaneously
- Noting the difference between the two drum readings when each set of lines clears (Correct answer)
- Setting the drum to –3.50 and reading prism
- Measuring the sphere and doubling it
Correct answer: Noting the difference between the two drum readings when each set of lines clears
Cylinder power equals the algebraic difference between the two drum readings (first meridian minus second meridian) when each set of lines sharpens.
Question 5: A keratometer (ophthalmometer) is used to measure:
- Intraocular pressure
- The curvature of the anterior corneal surface (Correct answer)
- The thickness of the crystalline lens
- The refractive power of the entire eye
Correct answer: The curvature of the anterior corneal surface
The keratometer measures the radius of curvature of the anterior corneal surface, typically used for contact lens fitting.
Question 6: When using an ultrasonic cleaner for eyewear, frames with which type of lens treatment should be cleaned with caution or avoided?
- Standard CR-39 lenses
- Anti-reflective (AR) coated lenses (Correct answer)
- Trivex lenses
- Photochromic lenses
Correct answer: Anti-reflective (AR) coated lenses
Ultrasonic cleaners can delaminate or damage anti-reflective coatings, so manufacturer guidelines should be followed for AR-coated lenses.
Question 7: On a lensometer, the axis scale reads in degrees from 0 to 180. When the axis drum shows 045, the cylinder axis is:
- 45 degrees from horizontal (Correct answer)
- 45 degrees from vertical
- Perpendicular to the 135-degree meridian
- The same as the 135-degree axis
Correct answer: 45 degrees from horizontal
An axis of 045 means the cylinder axis is oriented 45 degrees measured from the 0-degree (horizontal) meridian using the standard ANSI notation.
ABO NOCE Basic Opticianry Optical Instrumentation Use Questions and Answers 3
When using a pupillometer to measure monocular PDs, what is the correct patient fixation target?