ABO NOCE Basic Opticianry Dispensing Instrumentation Questions and Answers 5 — Questions and Answers
Question 1: Which type of pliers is preferred for adjusting metal frame temples to avoid surface damage?
- Flat-jaw steel pliers
- Smooth-jaw or nylon-tipped pliers (Correct answer)
- Chain-nose jewelry pliers
- Round-nose pliers
Correct answer: Smooth-jaw or nylon-tipped pliers
Smooth-jaw or nylon-tipped pliers prevent scratching and marring of metal frame surfaces during temple and bridge adjustments.
Question 2: When using a digital centration device (e.g., Essilor Visioffice or Rodenstock DNEye), the system captures:
- Only the monocular PD while the patient reads a chart
- 3D eye and facial measurements with the frame in place for full fitting data (Correct answer)
- The base curve of the frame's demo lens only
- The vertex distance without the frame on the patient
Correct answer: 3D eye and facial measurements with the frame in place for full fitting data
Digital centration systems photograph or video the patient wearing the chosen frame and calculate comprehensive fitting data including PD, heights, pantoscopic tilt, and vertex distance simultaneously.
Question 3: The primary purpose of a frame-warmer's temperature setting in dispensing is to:
- Sterilize the frame before patient fitting
- Heat plastic frames to a workable temperature without burning or discoloring them (Correct answer)
- Expand metal hinges for easier lens insertion
- Dry moisture from nylon supra frames
Correct answer: Heat plastic frames to a workable temperature without burning or discoloring them
Frame warmers maintain a controlled temperature—typically around 120–140°F—so zyl plastic becomes pliable without scorching or color change.
Question 4: In the context of dispensing instrumentation, a seg height stick is used to mark:
- The optical center on a finished distance-only lens
- The desired bifocal or progressive fitting height on the uncut lens or frame (Correct answer)
- The prism base direction on a prescribed lens
- The horizontal position of the near zone in a bifocal
Correct answer: The desired bifocal or progressive fitting height on the uncut lens or frame
A seg height stick or ruler is placed against the patient's face with the frame on to mark where the segment top or corridor start should be positioned.
Question 5: When a lensometer reading shows the sphere power is –2.00 D and the cylinder power is –1.00 D, the total power in the minus cylinder meridian is:
- –1.00 D
- –3.00 D (Correct answer)
- –2.00 D
- –0.50 D
Correct answer: –3.00 D
The total power in the most-minus meridian equals sphere plus cylinder: –2.00 + (–1.00) = –3.00 D.
Question 6: The purpose of an optical cross drawn from lensometer readings is to:
- Record the prism base direction for lab orders
- Graphically display the power in each major meridian for transposition and verification (Correct answer)
- Show the segment height relative to the optical center
- Map the progressive lens corridor length
Correct answer: Graphically display the power in each major meridian for transposition and verification
An optical cross illustrates the dioptric power at 90° and 180° (or the two principal meridians), making transposition between plus and minus cylinder forms straightforward.
Question 7: Which instrument reading confirms that a lens has been correctly decentered to produce a prescribed amount of prism by position rather than by grinding?
- A distometer showing the correct vertex distance
- A lensometer reading showing the prescription power with the target displaced by the corresponding prism amount (Correct answer)
- A Geneva lens clock showing the correct base curve
- A PD ruler showing the correct interpupillary distance
Correct answer: A lensometer reading showing the prescription power with the target displaced by the corresponding prism amount
When a lens is decentered to induce prism, the lensometer confirms the correct sphere/cylinder power while the displaced target position verifies the induced prism amount.
ABO NOCE Basic Opticianry Dispensing Instrumentation Questions and Answers 5
Which type of pliers is preferred for adjusting metal frame temples to avoid surface damage?