How to Read a Contact Lens Rx

Contact Lenses Direct is a replacement contact lens supplier only. We are not responsible for customers who order contact lenses without a valid contact lens prescription.  Please do not order contact lenses unless you know what brand, power, base curve, and diameter you require.  Please do not order contact lenses to “try on”. 

You will find most of the following prescription information on your current box of contact lenses. 

O.D. Designation for the Right eye.
O.S. Designation for the Left eye.
O.U. Designation for Both eyes.

BC: Designates the Base Curve, or inside curve of your contact lens. Base curve values are typically 8.0 through 9.2.

DIA: Designates the Diameter, or size of your contact lens. Diameters are represented with a numeric value usually between 13.0 and 15.0mm.

PWR: Designates the Power, or strength of your lens.  Examples of Power are -1.00, -3.00, +1.50, +1.75, etc.

Remember, it is important that you specify the (+) or (-) power of your lens.

Toric Contact Lenses

Toric Lens Wearers: Have these additional values in their prescription.

CYL: Designates the Cylinder, or strength of your astigmatism.  Examples of Cylinder measurements are -0.75, -1.00, -1.25, -1.50, -1.75.  Generally between -0.75 and -4.00.

AXIS: Designates the Axis, or the location of your astigmatism on your eye.  Examples of Axis measurements are 180, 170, 160, 090, 080, etc.  Axis is generally between 001 and 180 degrees.

Colored Contact Lenses

Color will also be included in the prescription.  This may include an enhancement or opaque tint – i.e. Blue, Aqua, or Amethyst. 

Bifocal Contact Lenses

ADD power will be included as a numeric value between +0.75 and +3.00.  This second power of the bifocal lens is in addition to the normal power measurement.

By Marion Evans