Does the Diameter of a Contact Lens Change Its Strength?

Contact lens prescriptions are based in part on the diameter of the lens and the strength. These are mutually exclusive items, and the diameter of the lens does not affect the strength of prescription.

Strength

The strength of your prescription is called the power of the lens. This is the amount the lens corrects your vision. Contact lens power is measured in diopters.

Diameter

Diameter is how wide your lens is. It is sometimes called Overall Diameter, or OAD, and is measured in millimeters at the widest point of the lens. This measurement can differ among people, although there are sizes that are more common than others.

Relationship

Changing the diameter of a lens will not change the strength. The different diameters offered by contact companies can be made in any strength, and vice versa. It is not the size of the lens that affects the vision correction it offers, but rather the strength of your prescription measured by a professional eye exam.

References

• Contact Lens.com: Help
• Art Optical: Glossary