Glasses prescriptions

How to read your glasses prescription

If you wear glasses, you've probably seen that piece of paper with a series of numbers and abbreviations that your optometrist hands you after your eye exam. Understanding your glasses prescription is crucial for ensuring you get the right lenses to correct your vision. In this article, we'll provide a comprehensive guide on how to read your glasses prescription, breaking down the numbers and terminology so you can confidently choose the perfect pair of glasses.

Understanding your glasses prescription

  1. OD and OS - Right and Left Eyes: Your prescription is typically divided into two parts, with the right eye labeled as "OD" (oculus dexter) and the left eye as "OS" (oculus sinister). Sometimes, you may also see "R" and "L" instead of OD and OS. Occasionally, if the prescription is the same for both eyes, you'll find "OU" (oculus uterque) or "BOTH."

  2. Sphere (SPH): The sphere, or SPH, indicates the main lens power needed to correct your vision. A positive number (+) signifies farsightedness (hyperopia), and a negative number (-) represents nearsightedness (myopia). The higher the number, the stronger the prescription.

  3. Cylinder (CYL): If you have astigmatism, your prescription will include a cylinder value (CYL). This measures the degree of astigmatism and is written as a negative or positive number.

  4. Axis (AXIS): The axis indicates the angle in degrees at which the cylinder power should be oriented to correct astigmatism.

  5. Addition (ADD): The addition value (ADD) is relevant for bifocals or progressive lenses and represents the additional power required for reading or close-up tasks. This is usually a positive number.

  6. Prism and Base (PRISM and BASE): Prism and base values are specified if you have eye alignment issues, such as double vision. The prism value indicates the displacement of the image, and the base tells the direction of the displacement (up, down, in, or out).

  7. Pupillary Distance (PD): The PD is the distance between the centers of your pupils and is crucial for ensuring that your lenses are correctly centered in your frames.

  8. Example Glasses Prescription:

    1. OD (Right Eye): -2.00 SPH, -0.75 CYL, 75 AXIS
    2. OS (Left Eye): -1.75 SPH, -1.25 CYL, 110 AXIS
    3. ADD: +2.25

    How to Choose the Right Frames

    Once you've deciphered your prescription, it's time to select your new glasses. Here are a few tips:
    1. Frame Size: Ensure that the frames are the right size for your face and fit comfortably. Your optician can help you find the best fit.

    2. Lens Type: Depending on your prescription, you might need single-vision lenses for near or distance vision, or multifocal lenses for both. Discuss your needs with your optometrist.

    3. Lens Material: The material of your lenses affects their thickness and weight. High-index lenses are thinner and lighter, which can be more comfortable for stronger prescriptions.

    4. Coatings: Consider adding anti-reflective, anti-scratch, or blue light blocking coatings to enhance the durability and functionality of your glasses.

    5. Style: Choose frames that suit your style and face shape. There's a wide range of frame designs to match your preferences.

    Reading your glasses prescription may seem complex at first, but with this guide, you can confidently understand the numbers and terminology. Remember to visit your optometrist for an accurate and up-to-date prescription. Armed with the knowledge of your prescription, you'll be better equipped to choose the right frames and lenses to improve your vision and express your personal style.