Ophthalmic Products and Materials Flashcards

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

Answer: Crown glass

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

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

Answer: Polycarbonate

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

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

Answer: Higher Abbe value and better optical clarity

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

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

Answer: Adhesion layer

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

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

Answer: UV light is blocked by the windshield

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

Which lens treatment is MOST effective at reducing glare from wet roads for a driver?

Answer: Polarized lenses

Polarized lenses eliminate horizontally polarized light that creates glare from flat reflective surfaces like wet roads, water, and snow.

A scratch-resistant coating on a CR-39 lens primarily increases the lens's resistance to scratching by:

Answer: Applying a hard silicone-based layer

Scratch-resistant (hard) coatings typically use silicone-based compounds applied via dip or spin coating to create a harder surface layer on plastic lenses.