NOCE Ophthalmic Products and Frames 2 — Questions and Answers
Question 1: Which frame material is most resistant to chemical solvents and is often recommended for patients who work in laboratory environments?
- Zyl (cellulose acetate)
- Nylon (polyamide) (Correct answer)
- Titanium
- Monel
Correct answer: Nylon (polyamide)
Nylon (polyamide) frames are highly resistant to chemical solvents and heat, making them suitable for laboratory or industrial environments.
Question 2: A patient's frame has a bridge size of 18 and an eye size of 52. Using the boxing system, what is the distance between lenses (DBL)?
- 18 mm (Correct answer)
- 52 mm
- 70 mm
- 34 mm
Correct answer: 18 mm
In the boxing system, the bridge size (DBL) is the measurement between the two lenses, which in this case is 18 mm.
Question 3: What is the primary advantage of a frame with a comfort cable temple compared to a standard skull temple?
- Better cosmetic appearance
- Greater retention behind the ear for active patients (Correct answer)
- Lighter overall frame weight
- Easier lens insertion
Correct answer: Greater retention behind the ear for active patients
Comfort cable temples wrap around the ear, providing greater retention, which is ideal for children and physically active patients.
Question 4: Which of the following lens materials has the highest Abbe value, indicating the least chromatic aberration?
- Polycarbonate (Abbe ~30)
- CR-39 (Abbe ~58) (Correct answer)
- High-index 1.74 (Abbe ~33)
- Trivex (Abbe ~43)
Correct answer: CR-39 (Abbe ~58)
CR-39 has an Abbe value of approximately 58, the highest among common ophthalmic plastics, meaning it produces the least chromatic aberration.
Question 5: A patient wants photochromic lenses but spends most of their time driving. What should you advise?
- Photochromics are ideal because car UV activates them fully
- Photochromics may not darken adequately inside a car because most windshields block UV (Correct answer)
- Photochromics darken faster in cars due to the greenhouse effect
- All photochromic brands work equally well behind glass
Correct answer: Photochromics may not darken adequately inside a car because most windshields block UV
Most car windshields are UV-laminated and block the UV light needed to activate standard photochromic lenses, limiting their darkening inside vehicles.
Question 6: What does the term 'base curve' refer to on an ophthalmic frame?
- The curvature of the front frame along the horizontal plane (Correct answer)
- The angle of the pantoscopic tilt
- The width of the bridge
- The distance from the front plane to the temple hinge
Correct answer: The curvature of the front frame along the horizontal plane
Base curve on a frame refers to the curvature of the front eyewire, measured in diopters, which determines how wrap-around the frame appears.
Question 7: Which coating is applied to lenses FIRST during the manufacturing process to serve as a foundation for other coatings?
- Anti-reflective coating
- Hard coat (scratch-resistant coat) (Correct answer)
- UV coating
- Mirror coating
Correct answer: Hard coat (scratch-resistant coat)
Hard coat (scratch-resistant coating) is typically applied first to provide a smooth, durable substrate for subsequent coatings such as anti-reflective layers.
NOCE Ophthalmic Products and Frames 2
Which frame material is most resistant to chemical solvents and is often recommended for patients who work in laboratory environments?