ABO NOCE Practice Test

For sphere power greater than 6.50, what is the tolerance percentage?

1. 1%

2. 3%

3. 2%

4. 4%

The correct answer is: 2%

When considering sphere power greater than 6.50 diopters, the correct tolerance percentage is 2%. This tolerance is established based on the varying level of precision required in optical fittings, particularly for higher prescription lenses. Higher sphere powers introduce a greater optical challenge, and thus, the acceptable margin of error, or tolerance, is generally set at 2%. This percentage ensures that lenses with higher powers maintain visual clarity and comfort for the wearer. While other percentages are listed, they do not adequately reflect the standards set for higher sphere power prescriptions in optical practice. For instance, a 1% tolerance would be unreasonably strict for such high powers, and higher percentages (like 3% or 4%) would not typically align with the precision required in this range, which helps in accurately correcting vision for those with significant refractive errors.