Regulating agencies such as the ANSI set specific standards for the performance of eyewear products, and each feature is allowed a tolerable range that must be adhered to in order to be approved. The following table lists the various tolerances for a sampling of contact lens parameters, established by ANSI, to ensure consistency in contact lens products.
Abbreviated Table of ANSI Standards for Contact Lenses
| Abbreviated Table of ANSI Standards for Contact Lenses | ||||
| PMMA | Rigid Gas Permeable | Flexible (Silicone Elastomer) | Soft Hydrogel (10-69% water) | |
| Overall Diameter (± mm) | 0.10 | 0.10 | 0.20 | 0.20 |
| Base Curve Radius (± mm) | 0.025 | 0.05 | 0.10 | 0.20 |
| Center Thickness | 0.02 | 0.02 | 0.02 | uses a percentage formula |
| Spherical Refractive Power (± diopters) | ||||
| 0.00 to 5.00 D | 0.12 | 0.12 | 0.25 | 0.25 |
| 5.12 to 10.00 D | 0.18 | 0.18 | 0.25 | 0.25 |
| 10.12 to 15.00 D | 0.25 | 0.25 | 0.50 | 0.50 |
| 15.12 to 20.00 D | 0.37 | 0.37 | 0.50 | 0.50 |
| Over 20.00 D | 0.50 | 0.50 | 0.50 | 1.00 |
ANSI standard Z80.20 – 2016 (R2021)
Z80 committee standards for contact lenses (soft and rigid).
ANSI Publications of Interest To Contact Lens Fitters
Below we have listed the two publications of interest to the contact lens fitter. You may purchase them directly from the American National Standards Institute at the following address:
American National Standards Institute
25 West 43rd Street
4th Floor
New York, NY 10036
(212) 642-4900
- Contact Lens Care Products: Vocabulary, Performance, Specifications, and Test Methodology ANSI Z80.20-2010
- Ophthalmics – Contact Lenses – Standard Terminology, Tolerances, Measurements, and Physicochemical Properties ANSI Z80.18-2010
You will most likely be required to know the abbreviated table of ANSI Standards for contact lens tolerances. However, to be completely prepared, we recommended purchasing both texts. You can also purchase the most current version of the Z80 committee standards for contact lenses: Z80.20-2016 (R2021)
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