ABO NOCE Basic Opticianry Dispensing Instrumentation Questions and Answers 2 — Questions and Answers
Question 1: When using a lensometer to verify a progressive addition lens, where should the distance power be confirmed?
- In the near zone at the bottom of the lens
- In the upper portion of the lens through the distance corridor (Correct answer)
- At the geometric center of the lens
- At the segment line midpoint
Correct answer: In the upper portion of the lens through the distance corridor
The distance power of a progressive lens is verified through the upper distance zone of the lens on the lensometer.
Question 2: Which instrument is used to measure the base curve of a finished spectacle lens?
- Pupillometer
- Geneva lens clock (lens gauge) (Correct answer)
- Lensometer
- Distometer
Correct answer: Geneva lens clock (lens gauge)
The Geneva lens clock (lens gauge) measures the surface curvature, allowing the base curve of a spectacle lens to be determined.
Question 3: A pupillometer is primarily used to measure:
- The optical center height of finished lenses
- The binocular and monocular pupillary distances (Correct answer)
- The vertex distance of the frame
- The segment height of bifocal lenses
Correct answer: The binocular and monocular pupillary distances
A pupillometer measures the distance between a patient's pupils, both binocularly and monocularly, to ensure accurate lens centration.
Question 4: When neutralizing a lens with a lensometer, a spherical lens is confirmed when:
- Both lines of the target are clear at two different drum readings
- Both lines of the target are clear simultaneously at the same drum reading (Correct answer)
- One line is clear while the other is blurred at all settings
- The mires rotate as the drum is adjusted
Correct answer: Both lines of the target are clear simultaneously at the same drum reading
A pure sphere shows both target lines simultaneously in sharp focus at one drum reading, confirming no cylinder power.
Question 5: The distometer (or Rodenstock depth gauge) is used to measure:
- Lens thickness at the optical center
- Vertex distance between the back surface of the lens and the cornea (Correct answer)
- Pupillary distance under monocular conditions
- Frame bridge size
Correct answer: Vertex distance between the back surface of the lens and the cornea
A distometer measures the vertex distance, the space between the back surface of the spectacle lens and the anterior corneal surface.
Question 6: On a lensometer, the axis wheel is used to:
- Adjust the sphere power reading
- Rotate the eyepiece for observer focus
- Align the cylinder axis of the lens being measured (Correct answer)
- Change the add power reading
Correct answer: Align the cylinder axis of the lens being measured
The axis wheel rotates the target, allowing the dispenser to align the cylinder axis of the lens with the axis scale on the instrument.
Question 7: Which frame adjustment tool applies heat to allow reshaping of plastic (zyl) frames?
- Frame aligner
- Salt pan or frame warmer (Correct answer)
- Pliers with smooth jaw inserts
- Geneva lens clock
Correct answer: Salt pan or frame warmer
A salt pan or frame warmer heats plastic frames so they become pliable and can be reshaped without cracking or breaking.
ABO NOCE Basic Opticianry Dispensing Instrumentation Questions and Answers 2
When using a lensometer to verify a progressive addition lens, where should the distance power be confirmed?