Contact lens packaging and cases are printed with various letters and numbers, such as “PWR,” “BC,” “DIA,” “CYL,” “AXIS,” and “ADD.”
Have you ever wondered, “What do these numbers mean?” or “Which one is my contact lens power?”
In this article, we will explain the representative symbols found on contact lens packaging and cases in a clear and easy-to-understand manner.
What Is Printed on Contact Lens Packaging and Cases?
Contact lens packaging displays essential information indicating the lens power, size, curvature, and specifications.
While notations vary slightly by manufacturer, the most common symbols include:
- ・PWR / SPH / D: Lens power
- ・BC: Base curve
- ・DIA: Lens diameter
- ・CYL: Cylinder power (astigmatism power)
- ・AX / AXIS: Cylinder axis (astigmatism axis)
- ・ADD: Addition power (for multifocal lenses)
Let’s look at what each of these symbols represents.
① PWR / SPH / D | Contact Lens “Power”
- ・What is PWR / SPH / D?
“PWR,” “SPH,” and “D” all denote the lens power. Although the notation differs depending on the brand, they all indicate the prescription power measured in D (Diopters).
- ・− (Minus): Indicates nearsightedness (myopia)
- ・＋ (Plus): Indicates farsightedness (hyperopia)
For example, a marking of “-3.00” indicates a lens designed for myopia.
Please note that a contact lens prescription is not always identical to an eyeglass prescription. Due to vertex distance differences, the optimal prescription for glasses and contact lenses can vary, particularly for stronger prescriptions.
② BC | Contact Lens “Base Curve”
- ・What is BC?
“BC” stands for Base Curve, which represents the curvature of the inner surface of the contact lens, measured in mm (millimeters).
- ・Smaller value: Steeper curvature
- ・Larger value: Flatter curvature
The BC is a crucial parameter that determines how comfortably and securely the contact lens fits the shape of your eye.
③ DIA | Contact Lens “Diameter”
- ・What is DIA?
“DIA” stands for Diameter, representing the overall diameter of the contact lens itself, measured in mm.
For instance, “DIA 14.0mm” means the physical diameter of the lens is 14.0 millimeters.
Note for Colored Contact Lens Users: The “Graphic Diameter” (colored section) on colored contact lenses is different from “DIA.”
- ・DIA: The total diameter of the entire lens
- ・Graphic Diameter: The diameter of the portion containing color pigments Be careful not to confuse the two when purchasing colored lenses.
- ④ CYL | “Astigmatism Power” for Toric Contact Lenses
Lenses designed for astigmatism (toric lenses) often include the symbol “CYL.”
“CYL” stands for Cylinder, indicating the power used to correct astigmatism, measured in D (Diopters).
Toric lenses feature specialized power corrections in addition to standard spherical myopia/hyperopia power.
- ⑤ AX / AXIS | “Astigmatism Axis” for Toric Lenses
“AX” or “AXIS” represents the direction or angle of astigmatism.
Expressed in degrees (°) ranging from 0° to 180°.
For toric contact lenses, both CYL (astigmatism power) and AXIS (astigmatism angle) are required.
For example,
CYL −1.25 / AXIS 180 means an astigmatism power of −1.25 D and an axis of 180°.
- ⑥ ADD | “Addition Power” for Multifocal Lenses
Multifocal contact lenses feature the symbol “ADD.”
“ADD” stands for Addition, which represents the extra magnifying power added on top of your distance prescription to assist with near vision.
As presbyopia makes reading close up difficult with age, multifocal contact lenses serve as an effective option to clear up both distance and near vision.
Contact Lens Symbol Summary Table
| Symbol | Meaning | Unit / Format |
|---|---|---|
| PWR / SPH / D | Lens Power | D |
| BC | Base Curve | mm |
| DIA | Lens Diameter | mm |
| CYL | Cylinder Power (Astigmatism) | D |
| AX / AXIS | Cylinder Axis (Astigmatism) | ° |
| ADD | Addition Power (Multifocal) | D |
| Symbol | Meaning | Unit / Format |
|---|---|---|
| PWR / SPH / D | Lens Power | D |
| BC | Base Curve | mm |
| DIA | Lens Diameter | mm |
| CYL | Cylinder Power (Astigmatism) | D |
| AX / AXIS | Cylinder Axis (Astigmatism) | ° |
| ADD | Addition Power (Multifocal) | D |
Your Contact Lens Details Matter During ICL Evaluations!
During an initial ICL suitability exam at our clinic, we review the specifications of the contact lenses you currently wear.
Details such as your current lens type, prescription strength, and wearing habits provide vital baseline data when evaluating your comprehensive eye exam results.
If you are considering ICL surgery, we strongly recommend bringing your contact lens packaging or blister packs with you to your appointment.
Rather than relying on memory (“I think my prescription is around this number”), bringing the original packaging allows our clinical team to verify your precise parameters.
Summary | Keep Your Contact Lens Packaging for Reference
Contact lens packaging holds valuable optical information that is easy to overlook. Knowing what “PWR,” “BC,” and “DIA” mean helps you better understand your eyes and provides essential reference data when evaluating ICL surgery.
Please keep your contact lens boxes or foil lids and bring them along to your visit.
If you are interested in ICL, book an initial suitability consultation with our specialists to determine if ICL is right for your eyes and lifestyle!