Secret Contacts Codes – What do the Numbers on the Package mean?

Have you ever wondered what all the abbreviations, numbers and letters mean on your contact lens prescription or package? Are the secret codes on the contact lens package part of the big contacts conspiracy? You don’t need to speculate anymore.We’re here to reveal all the secrets of your contact lens prescription. Even though it’s not magic, it’s good to understand the standard terms. That’s especially true if you are ordering your contacts online or from a different provider than the one who prescribed your lenses!

Before we get down to the nitty-gritty of contacts codes, it’s worth mentioning that your eyeglass prescription and your contact lens prescription are not the same. In addition to the power, a contact lens prescription provides information about the size, material and curvature of the lens. The power may also be different owing to the fact that  contact lenses sit directly on the cornea where as eyeglasses sit around 12 mm from it ‒ the eyeglass prescription must account for that distance. Mild astigmatism is usually not corrected in the contact prescription. In this case, you get a spherical equivalent number. Where as, with your glasses prescription you get both spherical and cylinder numbers in your glasses prescription.

Common codes on your contacts package

Sph/PWR = This refers to the refractive power (or sphere) of the lens.This is the amount of correction, measured in diopters, that is needed to bring your vision to your maximum visual acuity.

Dia = Diameter, measured in millimeters. This number is usually between 13 and 14.5.

BC = Base Curve refers to the back curvature of the contact lens. This number is usually between 8 and 10.

Exp = The expiration month of the unopened contact lens package.

Toric contacts:

Cyl = Cylinder value in toric lenses – this is the amount of power needed to correct your astigmatism.

Ax/Axis = The orientation of the cylinder value on the lens. This number is displayed in degrees between 0 and 180°.

Multifocal contacts:

ADD: Add Power – the added magnifying power in portions of the lens to help with seeing up close (in diopters)

Contact lens packaging may include the brand name, lens material, possible UV-blocking quality and the water content. If the lenses are tinted, the color information is included as well.

Whatever the “recipe” of your contact lens prescription is, don’t forget to check your eyesight with them with the easee eye test!