NOCE Ophthalmic Products and Frames 5 — Questions and Answers
Question 1: Which frame measurement describes the total horizontal width of the frame front, from the outermost edge of one endpiece to the other?
- Eye size (A measurement)
- DBL (bridge size)
- Frame PD
- Total frame width (A + DBL + A) (Correct answer)
Correct answer: Total frame width (A + DBL + A)
The total frame width equals the sum of both eye sizes plus the DBL (A + DBL + A), spanning the full width of the frame front.
Question 2: A patient chooses polarized lenses. In which situation would polarized lenses be LEAST beneficial?
- Driving on wet roads
- Fishing on a clear lake
- Skiing on a bright sunny slope
- Looking at a car's LCD instrument cluster (Correct answer)
Correct answer: Looking at a car's LCD instrument cluster
Polarized lenses can make LCD screens appear dark or produce a black-out effect at certain angles, making instrument clusters or phone screens difficult to read.
Question 3: What is the primary optical purpose of a progressive addition lens (PAL)?
- To correct astigmatism with a cylindrical correction only
- To provide a seamless gradient of power from distance at the top to near at the bottom (Correct answer)
- To reduce chromatic aberration across the entire lens
- To increase the field of view in the peripheral zones
Correct answer: To provide a seamless gradient of power from distance at the top to near at the bottom
A PAL provides a continuous, invisible progression of plus power from the distance zone at the top to the reading zone at the bottom, eliminating the visible segment line.
Question 4: A patient's frame is made of memory metal (beta-titanium or Flexon). What is the key advantage of this material for active patients?
- It is completely non-conductive and safe in MRI machines
- It returns to its original shape after bending, reducing breakage (Correct answer)
- It has the highest Abbe value of any frame material
- It cannot be adjusted after manufacture
Correct answer: It returns to its original shape after bending, reducing breakage
Memory metal alloys (beta-titanium) are superelastic and return to their original shape after bending, making them very durable for active patients.
Question 5: When measuring a patient for frame fitting, the 'vertex distance' is measured from which two reference points?
- The front of the cornea to the back surface of the lens (Correct answer)
- The front of the cornea to the front surface of the lens
- The pupil center to the optical center of the lens
- The bridge of the nose to the back of the frame front
Correct answer: The front of the cornea to the back surface of the lens
Vertex distance is the distance from the front surface of the cornea (apex) to the back vertex (posterior surface) of the ophthalmic lens.
Question 6: What is the function of a 'skull temple' (also called a 'library temple') on an eyeglass frame?
- It wraps completely around the ear for maximum retention
- It rests straight back over the ear with a slight curve at the tip for light retention
- It is spring-loaded to grip the head firmly
- It extends straight back with no curve and is used primarily for reading glasses (Correct answer)
Correct answer: It extends straight back with no curve and is used primarily for reading glasses
A skull (library) temple extends straight back with little to no downward bend, resting lightly on the ear and allowing glasses to be slipped on and off easily.
Question 7: Which of the following correctly describes the role of the 'seg height' measurement in a lined bifocal fitting?
- The horizontal distance from the frame's optical center to the segment
- The vertical distance from the lowest edge of the lens to the top of the bifocal segment (Correct answer)
- The angle at which the reading segment is positioned relative to the frame
- The total width of the bifocal segment flat-top line
Correct answer: The vertical distance from the lowest edge of the lens to the top of the bifocal segment
Seg height is the vertical measurement from the bottom edge of the lens (or frame) to the top of the bifocal segment, ensuring the add power aligns with the patient's near vision posture.
NOCE Ophthalmic Products and Frames 5
Which frame measurement describes the total horizontal width of the frame front, from the outermost edge of one endpiece to the other?