ABO NOCE Basic Opticianry Dispensing Instrumentation 4 — Questions and Answers
Question 1: An optician uses a digital caliper during the dispensing process primarily to:
- Measure corneal curvature
- Precisely measure lens thickness, frame dimensions, or segment heights in millimeters (Correct answer)
- Determine the optical center of a lens
- Measure pupillary distance
Correct answer: Precisely measure lens thickness, frame dimensions, or segment heights in millimeters
Digital calipers provide precise millimeter measurements of lens thickness, frame component dimensions, and other critical physical parameters during dispensing.
Question 2: When using a hand-held magnifier or loupe during frame inspection, an optician is most likely looking for:
- The patient's PD
- Surface defects, scratches, or coating imperfections on the lens (Correct answer)
- The base curve of the lens
- The segment power of a bifocal
Correct answer: Surface defects, scratches, or coating imperfections on the lens
A loupe or magnifier is used to closely inspect lens surfaces for scratches, coating defects, inclusions, or other quality issues before dispensing.
Question 3: The primary purpose of a lens clock (Geneva gauge) in dispensing is to:
- Verify the prescription power written by the doctor
- Measure the sagittal curve (base or front curve) of a lens surface (Correct answer)
- Mark the optical center for edging
- Check the frame's pantoscopic tilt angle
Correct answer: Measure the sagittal curve (base or front curve) of a lens surface
The lens clock measures the sagittal depth of a lens surface to determine its curvature (base curve), which is useful for matching replacement lenses.
Question 4: An optician uses a protractor or angle gauge during frame adjustment to measure:
- The optical center position
- Pantoscopic tilt and face form (wrap) angle of the frame (Correct answer)
- The reading addition power
- The segment height
Correct answer: Pantoscopic tilt and face form (wrap) angle of the frame
A protractor or angle gauge measures pantoscopic tilt (vertical frame angle) and face form wrap angle to ensure proper optical alignment.
Question 5: When verifying a plano lens on a lensometer, the mires should appear:
- With a strong spherical shift requiring correction
- Clear and focused at zero power with no cylinder (Correct answer)
- Rotated to the 90° axis
- Split and unfocused regardless of the wheel setting
Correct answer: Clear and focused at zero power with no cylinder
A plano lens has no refractive power, so the lensometer mires should focus clearly at zero on the power drum with no cylinder present.
Question 6: Which instrument measures the near interpupillary distance (near PD) by accounting for the convergence of the eyes at a close working distance?
- A standard lensometer
- A pupillometer set to near mode or a near PD ruler with vergence compensation (Correct answer)
- A distometer
- A seg height gauge
Correct answer: A pupillometer set to near mode or a near PD ruler with vergence compensation
A pupillometer in near-mode or a calibrated near PD card accounts for the convergence of the eyes at near working distance, typically 40 cm.
Question 7: A screwdriver used in optical frame repair should have which tip to avoid stripping tiny eyeglass screws?
- A large flat-blade screwdriver tip
- A Phillips #3 head
- A precision flat-blade or JIS tip sized specifically for optical screws (Correct answer)
- An Allen (hex) key
Correct answer: A precision flat-blade or JIS tip sized specifically for optical screws
Optical screws are very small and require precision flat-blade or JIS screwdrivers matched to the screw head size to avoid stripping.
ABO NOCE Basic Opticianry Dispensing Instrumentation 4
An optician uses a digital caliper during the dispensing process primarily to: