ABO NOCE Basic Opticianry Ophthalmic Lenses and Materials 2

Question 1

Which lens material has the highest Abbe value among commonly used ophthalmic plastics?

Accepted Answer

CR-39 (Allyl diglycol carbonate)

Answer

Polycarbonate

Answer

Trivex

Answer

High-index 1.74

Question 2

A patient's prescription is -8.00 DS. Which lens material would BEST minimize edge thickness?

Accepted Answer

High-index 1.74

Answer

CR-39 (n=1.50)

Answer

Polycarbonate (n=1.586)

Answer

High-index 1.67

Question 3

What is the primary optical disadvantage of polycarbonate lenses compared to CR-39?

Accepted Answer

Lower Abbe value causing chromatic aberration

Answer

Lower impact resistance

Answer

Lower refractive index

Answer

Higher specific gravity

Question 4

An aspheric lens design primarily reduces which aberration compared to a spheric lens?

Accepted Answer

Marginal astigmatic error (oblique astigmatism)

Answer

Chromatic aberration

Answer

Petzval field curvature only

Answer

Prismatic effect at the optical center

Question 5

What does the term 'specific gravity' indicate about a lens material?

Accepted Answer

Its density relative to water, affecting lens weight

Answer

Its resistance to scratching

Answer

Its ultraviolet light absorption capability

Answer

Its ability to be tinted

Question 6

Which coating is applied FIRST directly to the lens substrate during the manufacturing process?

Accepted Answer

Hard coat (scratch-resistant coating)

Answer

Anti-reflective coating

Answer

Mirror coating

Answer

Anti-fog coating

Question 7

Which lens type would you recommend for a patient who needs both distance and near correction but refuses bifocals for cosmetic reasons?

Accepted Answer

Progressive addition lenses (PALs)

Answer

Single vision distance lenses with reading glasses

Answer

Flat-top bifocal with invisible segment

Answer

Lenticular lens design