NOCE Ophthalmic Products and Frames 3 — Questions and Answers
Question 1: A rimless mounting uses which component to secure the lens to the bridge and endpiece?
- A screw through a drilled hole in the lens (Correct answer)
- An epoxy adhesive bonded to the lens edge
- A metal channel crimped around the lens bevel
- A nylon cord seated in a groove around the lens
Correct answer: A screw through a drilled hole in the lens
Rimless (drilled) mountings use a screw or post that passes through a hole drilled in the lens to attach it to the bridge and endpiece hardware.
Question 2: What is the recommended minimum lens thickness at the drill point for a rimless mounting to prevent cracking?
- 1.0 mm
- 2.0 mm (Correct answer)
- 3.0 mm
- 0.5 mm
Correct answer: 2.0 mm
A minimum of 2.0 mm of lens material at the drill site is generally recommended to provide sufficient structural integrity and prevent cracking.
Question 3: A frame is described as having a 'keyhole bridge.' What does this describe?
- A bridge with a very narrow, elongated opening that contacts the nose on both sides (Correct answer)
- A bridge that adjusts for different nose widths via a sliding mechanism
- A rigid saddle bridge with no nose pads
- A bridge designed exclusively for high-minus prescriptions
Correct answer: A bridge with a very narrow, elongated opening that contacts the nose on both sides
A keyhole bridge has a narrow elongated shape, making contact on the sides of the nose, and is typically used on vintage or classic frame styles.
Question 4: Which frame adjustment increases the distance between the lens back vertex and the cornea?
- Increasing pantoscopic tilt
- Spreading the nose pads farther apart
- Extending the temple length
- Moving the nose pads forward to push the frame away from the face (Correct answer)
Correct answer: Moving the nose pads forward to push the frame away from the face
Moving nose pads forward on their arms pushes the frame away from the face, increasing vertex distance between the lens and the cornea.
Question 5: When fitting a high-plus power lens, which frame characteristic is MOST important to consider?
- A large eye size to maximize field of view
- A small eye size to minimize lens thickness and weight (Correct answer)
- A high wrap angle for better peripheral vision
- A rimless mounting to reduce lens weight
Correct answer: A small eye size to minimize lens thickness and weight
For high-plus lenses, a smaller eye size minimizes the center thickness and overall lens weight, improving comfort and cosmetics.
Question 6: What is the purpose of the 'A' measurement in the boxing system?
- The vertical height of the lens aperture
- The horizontal width of the lens aperture (Correct answer)
- The distance between lens geometric centers
- The overall frame front width
Correct answer: The horizontal width of the lens aperture
In the boxing system, the 'A' measurement is the horizontal width of the lens aperture (eyewire opening), measured across the widest point of the bounding box.
Question 7: A patient selects a frame with a very high base curve (e.g., 8 base). Which lens type is BEST suited for this frame?
- Standard flat-top bifocal lenses
- Wrap-designed or atoric lenses corrected for the tilt (Correct answer)
- Conventional spherical lenses with no modification
- High-index 1.74 lenses with a standard front curve
Correct answer: Wrap-designed or atoric lenses corrected for the tilt
Highly curved wrap frames require specially designed wrap or atoric lenses that compensate for the optical distortions introduced by the frame's tilt and curve.
NOCE Ophthalmic Products and Frames 3
A rimless mounting uses which component to secure the lens to the bridge and endpiece?