Spectacle Dispensing Procedures 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 Procedures flashcards as text
Vertex distance is the measurement from the:
Answer: Back surface of the lens to the corneal apex
Vertex distance is measured from the back vertex of the lens to the front surface of the cornea (corneal apex), typically 12–14 mm.
Which adjustment corrects a frame where one lens sits higher than the other when the patient wears it?
Answer: Adjust the nose pad heights unequally to level the frame
Uneven nose pad heights can compensate for facial asymmetry or unequal ear heights, leveling the frame in front of the patient's eyes.
For a prescription with +5.00 D sphere, changing vertex distance from 12 mm to 14 mm will effectively:
Answer: Reduce the effective plus power reaching the eye
Moving a plus lens farther from the eye reduces its effective power at the corneal plane, so a longer vertex distance weakens the effective plus power.
The minimum fitting height for a standard progressive lens is typically:
Answer: 18 mm
Most standard progressive lenses require a minimum fitting height of approximately 18 mm to accommodate the full progression corridor.
When a patient's bifocal segment top appears to float in and out of vision, the most likely cause is:
Answer: Segment height set too low
If the segment top is positioned too low, the patient must tilt their head or look down excessively, making the segment difficult to use consistently.
During frame adjustment, acetate frames should be heated using:
Answer: Hot sand or an air-bead frame warmer
Hot sand or an air-bead frame warmer provides even, controlled heat appropriate for softening acetate without scorching or melting the material.
The term 'face form' (wrap) describes:
Answer: The curve of the frame front from temporal to temporal to follow face curvature
Face form is the horizontal curvature of the frame front that matches the natural curvature of the face from one side to the other.