ABO NOCE Basic Opticianry Ophthalmic Lenses and Materials Questions and Answers 2

Question 1

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

Accepted Answer

CR-39

Answer

Polycarbonate

Answer

Trivex

Answer

High-index 1.74

Question 2

A lens with a base curve of +6.00 D and a front surface power of +6.00 D has what back surface power if the lens is -2.00 D?

Accepted Answer

-8.00 D

Answer

+4.00 D

Answer

-6.00 D

Answer

+8.00 D

Question 3

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

Accepted Answer

Greater optical clarity (higher Abbe value)

Answer

Higher refractive index

Answer

Lower cost

Answer

Greater thickness reduction

Question 4

In a progressive addition lens, the 'corridor' refers to which region?

Accepted Answer

The channel of usable power between distance and near zones

Answer

The reading zone at the bottom

Answer

The distance zone at the top

Answer

The peripheral blending area

Question 5

Which coating reduces glare from light sources at night and is especially beneficial for driving?

Accepted Answer

Anti-reflective (AR) coating

Answer

UV-absorbing coating

Answer

Mirror coating

Answer

Photochromic tint

Question 6

What does 'sagitta' (sag) describe in ophthalmic lens geometry?

Accepted Answer

The depth of a curved surface measured from its chord

Answer

The lens diameter

Answer

The optical center location

Answer

The edge thickness of the lens

Question 7

A patient requires +3.00 DS lenses. Which material would produce the thinnest lens for a typical frame?

Accepted Answer

High-index 1.74

Answer

CR-39 (n=1.50)

Answer

Polycarbonate (n=1.586)

Answer

High-index 1.67