Decoding Your Glasses Prescription: A Step-by-Step Guide

Decoding Your Glasses Prescription: A Step-by-Step Guide

Understanding your glasses prescription may seem like a daunting task with all the abbreviations and numbers. However, with a little guidance, you can easily decode your prescription and understand exactly what each term means for your vision. In this article, we will provide a simple guide to help you understand your glasses prescription.

Breaking Down the Prescription Terms

The first step in understanding your glasses prescription is becoming familiar with the common terms and abbreviations. Here’s a quick rundown of the basic optometrist acronyms and abbreviations you will encounter:

  • OD: It stands for “oculus dextrus,” which is Latin for right eye.
  • OS: This is short for “oculus sinister,” meaning the left eye in Latin.
  • SPH (Sphere): This indicates the amount of lens power, measured in diopters (D), prescribed to correct nearsightedness or farsightedness. If the number has a minus sign (-), you are nearsighted; if it has a plus sign (+), you are farsighted.
  • CYL (Cylinder): This number indicates the amount of lens power for astigmatism. If this column is blank, you have no astigmatism, or it’s so slight that it need not be corrected.
  • Axis: This describes the degree and direction of your astigmatism.
  • Pupillary Distance (PD): This is the distance between your pupils, which helps in aligning your glasses correctly.

You can learn more about these terms and their meanings by visiting our detailed guide on Understanding Eye Prescriptions.

Understanding the Numbers

Decoding Your Glasses Prescription: A Step-by-Step Guide

Photo by Karolina Grabowska

After you’ve familiarized yourself with the terms, the next step is to understand how to read the numbers in your glasses prescription. Each term will be followed by a number that represents a specific aspect of your vision correction.

  • SPH: The sphere number in your prescription is followed by a ‘+’ or ‘-‘ sign. A ‘-‘ sign indicates nearsightedness, meaning you have trouble seeing far away. A ‘+’ sign indicates farsightedness, meaning you have trouble seeing up close. The higher the number, the stronger your prescription.
  • CYL and Axis: If you have astigmatism, you’ll see a cylinder number and an axis number. The cylinder number indicates the severity of your astigmatism, while the axis number (between 1 and 180) indicates the orientation of the astigmatism.
  • PD: The pupillary distance is measured in millimeters and ensures that your lenses are positioned correctly. It can be one number (like 60), or two (like 30.0/30.0), the latter representing the distance for each eye from the center of the bridge of your nose.

Choosing the Right Glasses

Now that you understand your glasses prescription, choosing the right glasses becomes a much easier task. You can explore different types of lenses such as progressive lenses or reading glasses based on your prescription and lifestyle needs. Moreover, with the correct pupillary distance, you can ensure the lenses are perfectly aligned for your eyes, providing clear and comfortable vision.

Remember, regular eye checkups are essential to maintain updated prescriptions and eye health. If you notice any significant changes in your vision, schedule an appointment with your eye care provider immediately.

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Dr. Steven Liem

Dr. Steven Liem, O.D., F.A.A.O. is an optometrist based in Pasadena, California. After obtaining his doctorate from UC Berkeley’s School of Optometry, he completed his residency in Pediatrics, Vision Therapy & Rehabilitation and became a Fellow of the American Academy of Optometry. When he isn’t busy streaming or making Youtube videos about video games, Dr. Liem aims to broaden accessibility to vision health through his involvement in optometric industry and tech.