According to ANSI standards, which statement is correct for a lens ordered as 45.00 (7.50) -4.00 8.7 but received as 45.50 (7.42) -4.25 8.7?

In this scenario, the lens ordered had specific parameters including power and base curve measurements. According to ANSI (American National Standards Institute) standards, there are established tolerances for both power and base curve measurements that must be adhered to.

When examining the power, the initial order was for -4.00D, but the lens received was -4.25D. This represents a change of 0.25D, which typically exceeds the allowable tolerance for power in prescription lenses. ANSI standards generally allow a tolerance of ±0.13D for spherical power, meaning the difference here is beyond what is acceptable.

For the base curve, the ordered value was 7.50mm, and the lens received had a base curve of 7.42mm. This reflects an adjustment of 0.08mm. ANSI standards typically permit a slightly larger tolerance for base curves, but the specifics can vary based on the lens design. In many instances, adjustments in the base curve that are beyond the acceptable range also cannot be overlooked, especially when the primary spherical value has already exceeded tolerances.

Given that both the power and base curve adjustments do not fall within acceptable tolerances, it is concluded that neither the power nor the base curve meets ANSI standards