your glasses prescription doesn’t have to feel like solving a puzzle

Let’s break it down so you can understand what all those numbers and letters mean! A Simple Guide to Understanding Your Glasses Prescription Reading

Key Terms

1. OD (Oculus Dexter): Refers to the right eye.
2. OS (Oculus Sinister): Refers to the left eye.
3. OU (Oculus Uterque): Refers to both eyes (used less commonly).
4. Sphere (SPH): Indicates the strength of the lens needed to correct nearsightedness or farsightedness.
   What Does SPH Do?
   SPH tells you how much lens correction you need to bring your vision back to normal. It’s measured in diopters (a unit of lens strength) and addresses general spherical correction for your sight.
   Positive or Negative?
   • Negative (-) SPH: This corrects nearsightedness (you see better up close but struggle with far distances).
   • Positive (+) SPH: This corrects farsightedness (you see better far away but struggle up close).
   • 0.00 or Plano (Pl): Lucky you—this means no distance vision correction is needed!
   • The higher the SPH number, the stronger your prescription is, explains the American Academy of Ophthalmology (AAO).
5. Cylinder (CYL): Indicates the degree of astigmatism (if present). If blank, no astigmatism correction is needed.
6. Axis: Specifies the orientation of astigmatism correction (measured in degrees, 0–180).
7. Add (Addition): Represents additional magnification for reading or near vision (used in bifocal or progressive lenses).
8. PD (Pupillary Distance): Measures the distance (in millimeters) between the centers of your pupils, ensuring lenses are properly aligned.
   How to Read Each Part?
   1. Right Eye (OD) and Left Eye (OS):
      • For example:
        • OD: -2.50 SPH, -1.00 CYL x 90
        • OS: -1.75 SPH, -0.50 CYL x 180
      • Interpretation:
        • For the right eye: A sphere of -2.50 corrects nearsightedness, and a cylinder of -1.00 corrects astigmatism at an axis of 90°.
        • For the left eye: A sphere of -1.75 corrects nearsightedness, and a cylinder of -0.50 corrects astigmatism at an axis of 180°.
   2. Add (for Presbyopia):
      • Example: +2.00.
      • This means an additional 2.00 diopters of power is needed for near vision.
   3. Pupillary Distance (PD):
      • Example: 63 mm.
      • This ensures lenses are centered correctly in front of your pupils.

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   Common Abbreviations

   • Plano (PL): No prescription needed for that eye (0.00 SPH).
   • DS (Diopters Sphere): No astigmatism correction required (only SPH value is provided).
   • NV (Near Vision): Indicates prescription for reading glasses.

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   Example Prescription

   • OD: -2.00 SPH, -0.75 CYL x 120
   • OS: -1.50 SPH, -1.00 CYL x 90
   • Add: +1.50
   • PD: 64 mmInterpretation:
     • The right eye (OD) needs correction for mild nearsightedness (-2.00 SPH) and moderate astigmatism (-0.75 CYL) at an axis of 120°.
     • The left eye (OS) also requires correction for mild nearsightedness (-1.50 SPH) and moderate astigmatism (-1.00 CYL) at an axis of 90°.
     • The “Add” of +1.50 is for reading or near vision.
     • PD of 64 mm ensures the lenses align with the eyes.

       Making Sense of Your Glasses Prescription – What You Need to Know

       Not every prescription will include all the abbreviations and numbers you’ve heard about—only what’s relevant to your specific eye needs. Your prescription is unique to you, and here’s what to keep in mind:

       It’s Personalized

       Your prescription reflects your eyes’ individual requirements, so the details will vary. Some abbreviations, like SPH or CYL, may appear if you need correction for nearsightedness, farsightedness, or astigmatism. Others, like ADD, show up only if you need help with close-up tasks.

       Each Eye May Be Different

       It’s common for the numbers to differ between your right and left eyes—they’re not always identical!

       Prescriptions Change Over Time

       As your vision evolves, so does your prescription. Scheduling regular eye exams is the best way to ensure your glasses stay effective and comfortable.

       Your glasses prescription is a helpful tool to keep your vision at its best, so keeping it updated is essential. If you’re ever unsure about your prescription, your optometrist is always ready to help!

       If you have any specific prescription you’d like help interpreting, feel free to share!

       link to American academy of Ophthalmology