How To Read Your Eyeglass Prescription

Dec 14, 2017


Welcome to Baron Rick W Dr, your trusted source for eye health information. In this article, we will guide you through the process of understanding and interpreting your eyeglass prescription. We understand that navigating through the world of eye care can be overwhelming, but with our detailed breakdown, you'll be able to make informed decisions about your vision correction needs.

Understanding the Terminology

Before we dive into the details of your eyeglass prescription, let's familiarize ourselves with the terminology commonly used by eye care professionals:

  • OD: This stands for "oculus dexter" and refers to the right eye.
  • OS: This stands for "oculus sinister" and refers to the left eye.
  • Sphere (SPH): This indicates the lens power required to correct nearsightedness (-) or farsightedness (+).
  • Cylinder (CYL): This refers to the lens power needed to correct astigmatism.
  • Axis: This measures the orientation of the cylinder's correction for astigmatism.
  • Add (ADD): This specifies the added magnifying power for bifocal or progressive lenses.
  • Prism: This is prescribed for eye alignment issues and is usually accompanied by a direction and measurement.
  • Base: This describes the direction of the prism correction.
  • Pupillary Distance (PD): This measures the distance between your pupils and is important for ensuring the correct positioning of lenses in your eyeglass frames.

Deciphering Your Prescription

Now that you have an understanding of the terminology, let's dive into the various components of your eyeglass prescription:

Sphere (SPH)

The sphere power, indicated in diopters (D), determines the lens power required to correct your vision. A negative number (-) signifies nearsightedness, while a positive number (+) indicates farsightedness. The higher the number, the stronger the prescription.

Cylinder (CYL) and Axis

If you have astigmatism, your prescription may include cylinder and axis values. The cylinder power corrects the astigmatism, while the axis determines the orientation of the cylinder's correction. Both are measured in diopters (D).

Add (ADD)

The addition power (ADD) is relevant for individuals requiring multifocal lenses, such as bifocals or progressive lenses. It represents the additional magnifying power required for near vision tasks.

Prism and Base

A prism is prescribed to address eye alignment issues. If your prescription includes a prism, it will be accompanied by a measurement and a base direction (e.g., up, down, in, or out).

Pupillary Distance (PD)

Your pupillary distance (PD) is the measurement of the distance between your pupils. The accurate PD is crucial for ensuring that your lenses are properly centered within your frames, providing optimal visual clarity and comfort.

Tips for Interpreting Your Prescription

While understanding the prescription is important, it is also essential to keep the following tips in mind:

Consult an Eye Care Professional

While this guide aims to provide you with a basic understanding of your prescription, it is essential to consult your eye care professional for personalized advice. They will have comprehensive knowledge about your specific eye health needs and can address any concerns you may have.

Ask Questions

Don't hesitate to ask your eye care professional if you have any questions or need clarification. They are there to help you and ensure that you have a thorough understanding of your vision correction needs.

Regular Eye Exams

Keep in mind that your eyeglass prescription may change over time, so it's important to schedule regular eye exams. Your eye care professional will assess any changes in your vision and update your prescription accordingly.


Understanding your eyeglass prescription is an important step towards optimal vision correction. With this comprehensive guide, we hope to have provided you with the knowledge necessary to decode your prescription accurately. Remember, when in doubt, always consult your trusted eye care professional at Baron Rick W Dr for personalized guidance and recommendations tailored to your specific needs.

For more information about eye health and vision correction, visit Baron Rick W Dr.

Larry Gilmore
Informative and helpful!
Nov 8, 2023