ABO NOCE Basic Opticianry General Practice 4 — Questions and Answers
Question 1: A frame has an A measurement of 50 mm and a DBL of 20 mm. The patient's monocular PD is 31 mm. How much decentration is required per lens?
- 4 mm nasal decentration (Correct answer)
- 4 mm temporal decentration
- 2 mm nasal decentration
- No decentration needed
Correct answer: 4 mm nasal decentration
Frame geometric center to lens center = (A + DBL)/2 = (50+20)/2 = 35 mm; decentration = 35 − 31 = 4 mm nasally.
Question 2: Segment height for a flat-top bifocal is typically measured from the lowest rim of the frame to:
- The lower margin of the pupil (Correct answer)
- The center of the pupil
- The upper margin of the pupil
- The geometric center of the frame
Correct answer: The lower margin of the pupil
Flat-top bifocal seg height places the segment top at the lower pupil margin for standard fitting.
Question 3: Which lens treatment provides the greatest blockage of UV radiation?
- Photochromic lenses in their darkened (activated) state (Correct answer)
- Untreated CR-39
- Clear polycarbonate with AR coat only
- 80% gray tint on CR-39
Correct answer: Photochromic lenses in their darkened (activated) state
Fully activated photochromic lenses block essentially 100% of UVA and UVB radiation.
Question 4: A metal frame sits too low on the patient's nose. The optician should:
- Increase the splay angle of the nose pads (open them outward) (Correct answer)
- Decrease the splay angle of the nose pads
- Increase pantoscopic tilt
- Narrow the temple spread
Correct answer: Increase the splay angle of the nose pads (open them outward)
Opening the nose pads outward (increasing splay) raises the frame by changing the pad contact position on the nose.
Question 5: The Maddox rod test is used primarily to:
- Detect and measure phorias (latent muscle imbalances) (Correct answer)
- Measure vertex distance
- Determine pupillary distance
- Assess corneal topography
Correct answer: Detect and measure phorias (latent muscle imbalances)
The Maddox rod dissociates the eyes by converting a point light into a streak, revealing latent phorias.
Question 6: A lens requires a minimum finished diameter of 70 mm and 4 mm of total decentration. What minimum blank diameter is needed?
- 78 mm (Correct answer)
- 74 mm
- 70 mm
- 82 mm
Correct answer: 78 mm
Minimum blank size = finished diameter + (2 × decentration) = 70 + 8 = 78 mm.
Question 7: Which US federal regulation requires impact resistance for all ophthalmic dress eyewear lenses?
- FDA 21 CFR 801.410 (Correct answer)
- ANSI Z87.1
- ANSI Z80.1
- ISO 8980-1
Correct answer: FDA 21 CFR 801.410
FDA 21 CFR 801.410 mandates impact-resistant lenses for all prescription and non-prescription dress eyewear sold in the US.
ABO NOCE Basic Opticianry General Practice 4
A frame has an A measurement of 50 mm and a DBL of 20 mm.
The patient's monocular PD is 31 mm.
How much decentration is required per lens?