ABO ABO Industry Standards 4 — Questions and Answers
Question 1: Under FDA 21 CFR 801.410, dress ophthalmic lenses must pass the 'drop-ball test' using a steel ball of what diameter?
- 5/8 inch
- 1 inch (Correct answer)
- 5/16 inch
- 1/2 inch
Correct answer: 1 inch
The FDA drop-ball test requires that a 1-inch (25.4 mm) diameter steel ball dropped from 50 inches does not fracture the lens.
Question 2: What is the ANSI Z80.1 tolerance for cylinder axis in lenses with cylinder powers from 0.25D to 0.50D?
- ±3°
- ±5°
- ±7° (Correct answer)
- ±14°
Correct answer: ±7°
For cylinder powers between 0.25D and 0.50D, ANSI Z80.1 permits an axis tolerance of ±7°.
Question 3: In spectacle dispensing, 'pantoscopic tilt' refers to:
- The horizontal angle of the frame front relative to the face
- The vertical angle of the lens plane relative to vertical (Correct answer)
- The wrap angle of the frame temples around the head
- The angle between the two lenses in the frame
Correct answer: The vertical angle of the lens plane relative to vertical
Pantoscopic tilt is the vertical angle at which the lower edge of the lens is tilted toward the cheek relative to a vertical plane.
Question 4: Which of the following lens materials has the highest impact resistance, making it preferred for children's and safety eyewear?
- CR-39 plastic
- Crown glass
- Polycarbonate (Correct answer)
- High-index 1.67 plastic
Correct answer: Polycarbonate
Polycarbonate has the highest impact resistance of all common ophthalmic lens materials, making it the standard for safety and children's eyewear.
Question 5: When measuring the fitting height for a progressive addition lens, the measurement is taken from:
- The pupil center to the top of the frame
- The pupil center to the lowest edge of the frame (Correct answer)
- The pupil center to the datum line
- The lower limbus to the bottom of the frame
Correct answer: The pupil center to the lowest edge of the frame
PAL fitting height is measured from the center of the pupil vertically down to the lowest point of the lens aperture (bottom of the frame).
Question 6: The 'datum line' of a spectacle frame is defined as:
- The horizontal line connecting the optical centers of both lenses
- The horizontal line dividing the lens aperture into equal upper and lower halves (Correct answer)
- The line connecting the geometric centers of both lens apertures
- The line along the top edge of the frame front
Correct answer: The horizontal line dividing the lens aperture into equal upper and lower halves
The datum line is a horizontal line that bisects the lens aperture into two equal halves of the same vertical depth.
Question 7: According to ANSI Z80.1, what is the maximum allowable decentration for a single vision lens with no prescribed prism?
- 1.0 mm
- 2.0 mm
- 2.5 mm
- The Prentice rule determines if prism is within tolerance (Correct answer)
Correct answer: The Prentice rule determines if prism is within tolerance
ANSI Z80.1 does not specify a fixed decentration limit; instead, the induced prism at the reference point must fall within the allowable prism tolerance using Prentice's rule.
ABO ABO Industry Standards 4
Under FDA 21 CFR 801.410, dress ophthalmic lenses must pass the 'drop-ball test' using a steel ball of what diameter?