ANSI Z80.1 Standards and Tolerances Flashcards

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:

Answer: Exceeds tolerance for prescriptions ±3.37 D or less

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.

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

Answer: 0.50Δ

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

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

Answer: The point where prism and power are verified

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

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

Answer: ±0.75 D

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

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

Answer: 0.25Δ

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

When ANSI Z80.1 refers to 'surface quality,' which defect is specifically addressed?

Answer: Scratches, bubbles, and inclusions visible under diffuse light

ANSI Z80.1 surface quality standards address cosmetic defects such as scratches, bubbles, and inclusions that could affect optical performance or appearance.

A lens with a prescription of -9.00 D sphere: what sphere power tolerance does ANSI Z80.1 apply?

Answer: ±0.18 D

For lens powers exceeding ±6.50 D, ANSI Z80.1 applies a tolerance of ±2% of the prescribed power; 2% of 9.00 D = 0.18 D.