NOCE Ophthalmic Products and Materials 2

Question 1

Which lens material has the highest Abbe value, indicating the least chromatic aberration?

Accepted Answer

Crown glass

Answer

Crown glass has an Abbe value of approximately 59, the highest among common ophthalmic materials, meaning it produces the least chromatic aberration.

Question 2

A patient needs lenses with maximum impact resistance for safety eyewear. Which material is the BEST choice?

Accepted Answer

Polycarbonate

Answer

Polycarbonate is the most impact-resistant ophthalmic lens material and is the standard for safety eyewear and ANSI Z87.1 compliance.

Question 3

What is the primary advantage of Trivex over polycarbonate for ophthalmic lenses?

Accepted Answer

Higher Abbe value and better optical clarity

Answer

Trivex has an Abbe value of about 45 compared to polycarbonate's 30, providing significantly better optical clarity and less chromatic aberration.

Question 4

Which anti-reflective coating layer is responsible for bonding the AR stack to the lens surface?

Accepted Answer

Adhesion layer

Answer

The adhesion layer (base layer) chemically bonds the AR coating stack to the lens substrate, ensuring durability of the entire coating system.

Question 5

A photochromic lens that does not darken adequately in a car is most likely because:

Accepted Answer

UV light is blocked by the windshield

Answer

Modern automotive windshields block UV radiation, which is required to activate photochromic dye molecules, preventing the lenses from darkening inside a vehicle.

NOCE - National Opticianry Competency Examination Practice Test

NOCE - National Opticianry Competency Examination Practice Test

NOCE Ophthalmic Products and Materials 2