ABO NOCE Basic Opticianry Ophthalmic Products and Materials Questions and Answers 3

Question 1

Which lens treatment blocks the highest percentage of UV radiation for uncoated lenses without additional coating?

Accepted Answer

Polycarbonate lenses

Answer

Polycarbonate inherently blocks nearly 100% of UV radiation up to 380nm without any additional UV coating.

Question 2

A scratch-resistant coating on a plastic lens primarily adds hardness by:

Accepted Answer

Depositing a thin layer of silica-based compound

Answer

Scratch-resistant (hard) coatings use silica-based or similar inorganic compounds applied in thin layers to harden the plastic surface.

Question 3

What is the main advantage of Trivex over polycarbonate for ophthalmic use?

Accepted Answer

Higher Abbe value (less chromatic aberration)

Answer

Trivex has an Abbe value of approximately 45 compared to polycarbonate's 30, resulting in better optical clarity with less chromatic aberration.

Question 4

A hydrophobic coating on an ophthalmic lens is designed to:

Accepted Answer

Repel water and make the lens easier to clean

Answer

Hydrophobic (water-repellent) coatings cause water to bead up and roll off, making the lens surface easier to clean and maintain.

Question 5

Which frame material is known for its shape memory properties and returns to its original shape after bending?

Accepted Answer

Memory metal (Flexon/titanium alloy)

Answer

Memory metal frames (such as Flexon) are made from titanium-nickel alloys that spring back to their original shape after bending.

ABO NOCE Basic Opticianry Practice Test