ABO NOCE Basic Opticianry Spectacle Dispensing and Fitting 3 — Questions and Answers
Question 1: The term 'seg height' in progressive addition lenses refers to the measurement from:
- The top of the lens to the optical center
- The bottom of the frame to the fitting cross or pupil center (Correct answer)
- The distance PD to the near PD
- The lens edge to the bifocal segment top
Correct answer: The bottom of the frame to the fitting cross or pupil center
Seg height (fitting height) for progressive lenses is measured from the lowest point of the frame to the patient's pupil center or the fitting cross.
Question 2: A patient requests a frame with a very small B measurement. Which lens type will be most problematic to fit in this frame?
- Single vision distance
- Flat-top 28 bifocal
- Progressive addition lens (Correct answer)
- Plano sunwear
Correct answer: Progressive addition lens
Progressive addition lenses require adequate B measurement (vertical height) to accommodate the full progressive corridor from distance to near.
Question 3: When a patient's glasses cause a red mark on the nose, the best immediate adjustment is to:
- Widen the nose pad spread (Correct answer)
- Increase the pantoscopic tilt
- Tighten the frame front
- Lower the temples
Correct answer: Widen the nose pad spread
Widening the nose pad spread distributes the frame weight over a larger area, reducing pressure that causes red marks.
Question 4: Pantoscopic tilt is best described as:
- The horizontal angle of the frame front relative to the face
- The downward tilt of the bottom of the lens relative to the top (Correct answer)
- The angle formed between the temples and the frame front
- The wrap of the frame around the face
Correct answer: The downward tilt of the bottom of the lens relative to the top
Pantoscopic tilt is the vertical angle where the bottom of the frame front tilts toward the face, typically 8–12 degrees for optimal optical performance.
Question 5: For every 2 degrees of pantoscopic tilt added, the optical center should be moved:
- 1mm upward
- 1mm downward (Correct answer)
- 0.5mm upward
- 0.5mm downward
Correct answer: 1mm downward
For every 2 degrees of pantoscopic tilt, the optical center should be lowered by 1mm to maintain proper optical alignment with the pupil.
Question 6: Which measurement is used to determine the minimum blank size needed to cut a lens for a given frame?
- Effective diameter (ED) (Correct answer)
- Distance between lenses (DBL)
- Boxing system A + DBL
- Pupillary distance
Correct answer: Effective diameter (ED)
The effective diameter (ED) of the frame, combined with decentration, determines the minimum blank size required to fully fill the frame with the correct PD.
Question 7: A patient with a high plus prescription is fitted with a frame where the optical centers are decentered outward. What optical problem results?
- Base-in prism (Correct answer)
- Base-out prism
- Vertical prism
- No prism effect
Correct answer: Base-in prism
Decentering plus lenses outward places the optical center temporally, inducing base-in prism, which is typically unwanted.
ABO NOCE Basic Opticianry Spectacle Dispensing and Fitting 3
The term 'seg height' in progressive addition lenses refers to the measurement from: