NOCE Spectacle Dispensing Procedures 4 — Questions and Answers
Question 1: A hyperopic patient requires +4.00 lenses. To minimize lens thickness, the dispenser should recommend:
- A frame with a large eye size and high base curve
- A frame with a small eye size and a high-index lens material (Correct answer)
- A rimless frame with a standard CR-39 lens
- A wrap frame with a flat base curve
Correct answer: A frame with a small eye size and a high-index lens material
Small eye sizes reduce center thickness in plus lenses, and high-index materials reduce thickness further by requiring less curvature for the same power.
Question 2: Which adjustment corrects a frame that causes the lenses to appear tilted nasally downward on the patient's face?
- Increase face form angle symmetrically
- Spread the left nose pad and close the right nose pad (Correct answer)
- Adjust the left temple to be longer than the right
- Bend both temples outward equally
Correct answer: Spread the left nose pad and close the right nose pad
Unequal nose pad adjustment (spreading one side, closing the other) levels and rotates the frame front to correct a nasal tilt.
Question 3: When measuring monocular PDs for progressive lens fitting, the measurement is taken from the center of which anatomical structure?
- The outer canthus to the pupil center
- The nasal bridge midline to each pupil center (Correct answer)
- The limbus edge to the frame center
- The inner canthus to the pupil center
Correct answer: The nasal bridge midline to each pupil center
Monocular PD is measured from the bridge midline (root of the nose) to the center of each pupil independently.
Question 4: A patient presents with a prescription of OD +2.00 –1.50 × 90 and OS +1.75 –1.25 × 85. When verifying on the lensometer, the optician should verify the cylinder axis is within what ANSI Z80.1 tolerance for this power?
- ±1°
- ±2°
- ±3° (Correct answer)
- ±5°
Correct answer: ±3°
ANSI Z80.1 allows ±3° axis tolerance for cylinder powers between 0.25 D and 0.50 D (up to 1.50 D cyl), and tighter for higher cylinders.
Question 5: A patient fitted with a new single vision Rx reports blurry vision in primary gaze but clear vision when they tilt their head. This most likely indicates:
- Incorrect cylinder axis
- Optical centers placed too high or too low relative to the pupils (Correct answer)
- Incorrect sphere power
- Insufficient pantoscopic tilt
Correct answer: Optical centers placed too high or too low relative to the pupils
When OCs are vertically misplaced, the patient involuntarily tilts their head to bring the pupil into alignment with the OC.
Question 6: What is the purpose of the 'fitting cross' marked on a progressive lens before edging?
- Marks the optical center of the distance zone
- Marks the pupil alignment point used to set fitting height (Correct answer)
- Identifies the near add power location
- Indicates the corridor width
Correct answer: Marks the pupil alignment point used to set fitting height
The fitting cross is placed at the patient's pupil level to set the lens' intermediate corridor in the correct vertical position.
Question 7: Which of the following frame materials has the lowest density (lightest weight per unit volume)?
- Zylonite (cellulose acetate)
- Titanium
- Beryllium
- TR-90 nylon (Correct answer)
Correct answer: TR-90 nylon
TR-90 is an ultra-lightweight thermoplastic nylon with one of the lowest densities of all spectacle frame materials.
NOCE Spectacle Dispensing Procedures 4
A hyperopic patient requires +4.00 lenses.
To minimize lens thickness, the dispenser should recommend: