ABO NOCE Basic Opticianry Verification of Progressive Lenses 3

Question 1

The near reference point (NRP) of a progressive lens is typically located how far below the fitting cross?

Accepted Answer

12 mm

Answer

The near reference point is typically located approximately 12 mm below the fitting cross, though this varies slightly by lens design.

Question 2

A progressive lens has visible engraving marks at the 135° and 45° positions. What do these marks primarily indicate?

Accepted Answer

The nasal and temporal lens identification marks used to locate the PRP and other reference points

Answer

The permanent engravings at roughly 135° and 45° are manufacturer identification marks used to locate the PRP and decode the lens design and reference points.

Question 3

When verifying add power of a progressive lens, you read +1.75 D through the near reference point but the Rx calls for +2.00 D add. This is:

Accepted Answer

Outside ANSI tolerance and the lens must be reordered

Answer

The difference of 0.25 D equals the ANSI tolerance limit, but since this reading is at the boundary and below the prescribed add, it is outside acceptable tolerance and requires reorder.

Question 4

A patient's progressive lenses are verified and the monocular PDs are each 1.5 mm wider than prescribed. What visual complaint would this most likely cause?

Accepted Answer

Base-in prismatic effect causing convergence difficulty for near tasks

Answer

When the lenses are placed too far apart (wider PD), a base-in prism effect is induced, causing the eyes to over-converge for near vision.

Question 5

What is the ANSI Z80.1 standard for horizontal prism imbalance between OD and OS at the distance reference point of a progressive lens?

Accepted Answer

0.67 prism diopters

Answer

ANSI Z80.1 allows up to 0.67 prism diopters of horizontal imbalance between the two lenses at the distance reference point.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Verification of Progressive Lenses 3