ABO NOCE Basic Opticianry ANSI Z80.1 Standards and Tolerances 3

Question 1

A finished single-vision lens is measured and found to have 0.40Δ of unwanted horizontal prism at the MRP. According to ANSI Z80.1, this lens:

Accepted Answer

Exceeds tolerance for prescriptions ±3.37 D or less

Answer

ANSI Z80.1 allows only 0.33Δ of horizontal prism at the major reference point for prescriptions up to ±3.37 D, so 0.40Δ exceeds tolerance.

Question 2

For a bifocal lens, ANSI Z80.1 specifies the vertical prism imbalance between the two segment optical centers should not exceed:

Accepted Answer

0.50Δ

Answer

ANSI Z80.1 allows up to 0.50Δ of vertical prism imbalance between the two segments of a bifocal lens.

Question 3

What does ANSI Z80.1 define as the 'major reference point' (MRP) on a finished lens?

Accepted Answer

The point where prism and power are verified

Answer

The MRP is the verification point on the lens where the specified prism and power are measured and confirmed.

Question 4

According to ANSI Z80.1, what is the allowable tolerance for base curve on an uncut lens?

Accepted Answer

±0.75 D

Answer

ANSI Z80.1 allows a base curve tolerance of ±0.75 D for uncut finished lenses.

Question 5

Under ANSI Z80.1, what is the tolerance for vertical prism at the MRP when the prescription includes no prescribed prism?

Accepted Answer

0.25Δ

Answer

ANSI Z80.1 limits unwanted vertical prism to 0.25Δ at the MRP when no prism is prescribed.

ABO NOCE Basic Opticianry Practice Test