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How to Read Your Eyeglass Prescription | Step-by-Step Guide

Mar 19, 2026
How to Read Your Eyeglass Prescription | Step-by-Step Guide

Introduction

Understanding your prescription is the first step to getting the perfect pair of glasses online. A prescription is a written document from an optometrist that contains the optical power needed to correct your vision. Whether you’re renewing old glasses or buying first-time online, this guide will help you decode every number and symbol with confidence.

Key Abbreviations & Meanings

1.1 Right & Left Eyes

  • R / OD (Oculus Dexter): Right Eye
  • L / OS (Oculus Sinister): Left Eye
    Note: Always double-check that you haven’t mixed up the left and right lenses.

1.2 SPH (Sphere) — Ball Correction

  • What it is: Corrects myopia (nearsightedness) or hyperopia (farsightedness).
  • The Numbers:

◦ Minus (-): Nearsighted. Example: -3.50 means 350 degrees nearsighted.

◦ Plus (+): Farsighted. Example: +1.25 means 125 degrees farsighted.

◦ 0.00: No vision correction needed for this eye.

1.3 CYL (Cylinder) & AXIS — Astigmatism Correction

  • CYL: Corrects astigmatism (blurry vision caused by an irregular cornea).

A value of 0.00 or — means no astigmatism.

  • AXIS: Specifies the direction of the astigmatism (ranges from 0 to 180 degrees).

Critical: If you have CYL, you must include the AXIS for online ordering.

1.4 PD (Pupillary Distance) — The Most Important Measurement

  • What it is: The distance (in millimeters) between the centers of your pupils.
  • Why it matters: An inaccurate PD causes eye strain, headaches, and blurred vision.
  • Typical range: Adults usually range from 58mm to 64mm.

1.5 Optional Advanced Metrics

  • ADD: Addition power for reading glasses or progressive lenses (often seen in the lower section).
  • VA (Visual Acuity): Your visual sharpness (e.g., 20/20 is normal vision).

Example Prescription Breakdown

Let’s decode a typical prescription:

  • Right Eye (R): SPH -2.75 | CYL -0.50 | AXIS 180
  • Left Eye (L): SPH -3.00 | CYL -0.75 | AXIS 165
  • PD: 63mm

Translation:
Right eye: 275 degrees nearsighted with 50 degrees astigmatism at axis 180.
Left eye: 300 degrees nearsighted with 75 degrees astigmatism at axis 165.
Pupillary distance: 63mm.

Pro Tips for Online Ordering

  • Check the Date: Your prescription is usually valid for 12 months. Avoid using old data.
  • Astigmatism Caution: If your CYL is above -0.75, please ensure your AXIS is precise to prevent discomfort.
  • Single Vision PD vs. Monocular PD: For premium fitting, we recommend a monocular PD (measured separately for each eye).
  • Shop The Right Lenses.Ready to order? Upload your prescription and choose from our premium range of blue light blocking lenses, photochromic lenses, or high-index lenses for the sharpest vision possible.

FAQs

Q: Can I use a computer-generated refraction sheet?
A: We highly recommend using the final prescription from your eye doctor’s handwritten note. Computer printouts are initial estimates and may not be accurate.

Q: My PD is slightly different on two visits. Which one do I use?
A: Use the latest measurement. If the difference is significant (over 3mm), consult your optometrist again.

Q: How can I measure PD at home?
A: You can follow our detailed PD Measurement Guide or visit a local optical store for a quick check.

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