How to Read Contact Lens Prescription

July 28, 2023

Reading a contact lens prescription may seem daunting at first, but it's actually straightforward once you understand the different components. Here's a step-by-step guide on how to read a contact lens prescription:how to read contact lens prescription

  1. OD and OS: The prescription will typically start with "OD" and "OS," which stand for "oculus dexter" (right eye) and "oculus sinister" (left eye), respectively. Sometimes, you might also see "OU" for "oculus uterque," indicating the prescription applies to both eyes.

  2. Sphere (SPH) or Power (PWR): This is the main part of the prescription and represents the lens power in diopters (D). If you have nearsightedness (myopia), the number will be preceded by a minus sign (-), and if you have farsightedness (hyperopia), it will be preceded by a plus sign (+). The higher the number, the stronger the prescription.

  3. Cylinder (CYL): If you have astigmatism, this value will be present in your prescription. It indicates the amount of astigmatism in diopters and can have a plus or minus sign.

  4. Axis: If you have a cylinder value, you will also have an axis value. The axis specifies the orientation of the astigmatism correction, represented in degrees from 1 to 180.

  5. Addition (ADD): This value is typically found in prescriptions for multifocal or bifocal lenses. It indicates the additional power needed for close-up vision in diopters.

  6. Base Curve (BC): This is the curvature of the contact lens, which is matched to the shape of your eye. It's usually represented as a number between 8.0 and 9.0.

  7. Diameter (DIA): The diameter of the contact lens is given in millimeters and determines how large the lens is.

  8. Brand and Manufacturer: Your prescription may include the brand and manufacturer of the prescribed contact lenses.

Remember, contact lens prescriptions are specific to the individual and should not be used by others. Always consult with an eye care professional to ensure you have the correct prescription for your eyes.

Additionally, it's important to have regular eye exams to check for any changes in your prescription and ensure the health of your eyes while using contact lenses.