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

CR-39 has the highest Abbe value (~58) among common plastics, meaning it produces the least chromatic aberration.

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

Back surface power = total power − front power = -2.00 − (+6.00) = -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

Trivex has an Abbe value around 45 compared to polycarbonate's ~30, resulting in better optical clarity.

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 corridor (or progressive zone) is the narrow channel connecting the distance and near portions where power gradually increases.

Question 5

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

Accepted Answer

Anti-reflective (AR) coating

Answer

AR coatings eliminate surface reflections, significantly reducing glare and halos around lights during nighttime driving.

ABO NOCE Basic Opticianry Practice Test