Dispensing Instrumentation Flashcards
7 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Dispensing Instrumentation flashcards as text
On an automated lensometer, what advantage does it offer over a manual lensometer for verifying a progressive addition lens (PAL)?
Answer: It automatically maps the entire lens power distribution and identifies the corridor
Automated lensometers can map the full power profile of a PAL, displaying the distance, intermediate, and near zones along with the corridor.
The Geneva lens clock (lens gauge) is calibrated assuming a refractive index of:
Answer: 1.523
The Geneva lens clock is calibrated based on a refractive index of 1.523 (standard crown glass), so readings for high-index lenses must be corrected.
Which tool is used to mark the optical center and axis of a spectacle lens before edging?
Answer: The lensometer with a marking device
The lensometer is used to locate the optical center and axis of a lens, and a marking device (dotting system) places ink dots on the lens surface before it is edged.
A frame ruler (millimeter ruler) used in dispensing most commonly measures which parameters?
Answer: Eye size, bridge width, and temple length from frame markings
A frame ruler is used to read or verify the three-part frame size (eye size × bridge + temple length) inscribed on the frame.
A seg height gauge is used to measure:
Answer: The vertical distance from the bottom of the frame to the top of the bifocal segment
The seg height gauge measures the vertical placement of the bifocal segment top relative to the frame's lowest point, ensuring proper fitting for the patient's near vision needs.
Which type of pliers is specifically designed to make precise bends in metal eyeglass frames without marring the surface?
Answer: Round-nose forming pliers with nylon tips
Nylon-tipped pliers protect the metal frame surface from scratches and dents while allowing controlled bending during adjustments.
A prescription calls for 2.00 prism diopters base-in OD. When verifying this on the lensometer, the optical center dot should be displaced:
Answer: Nasally (toward the nose) on the lens
Base-in prism deviates light toward the base (inward), so the optical center must be displaced nasally (inward) to produce the prismatic effect.