Spectacle Dispensing and Fitting 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 Spectacle Dispensing and Fitting flashcards as text
The term 'seg height' in progressive addition lenses refers to the measurement from:
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.
A patient requests a frame with a very small B measurement. Which lens type will be most problematic to fit in this frame?
Answer: Progressive addition lens
Progressive addition lenses require adequate B measurement (vertical height) to accommodate the full progressive corridor from distance to near.
When a patient's glasses cause a red mark on the nose, the best immediate adjustment is to:
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.
Pantoscopic tilt is best described as:
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.
For every 2 degrees of pantoscopic tilt added, the optical center should be moved:
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.
Which measurement is used to determine the minimum blank size needed to cut a lens for a given frame?
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.
A patient with a high plus prescription is fitted with a frame where the optical centers are decentered outward. What optical problem results?
Answer: Base-in prism
Decentering plus lenses outward places the optical center temporally, inducing base-in prism, which is typically unwanted.