How to Read a Prescription for Glasses

Having a hard time figuring out your prescription so you can order glasses online?

Reading Prescriptions for Glasses

Eyeglasses prescriptions can be pretty hard to look at if you’ve never had to read one before, and entering your information online can be nerve-wracking if you’re not sure you’re doing it right.

If you want to learn how to read a prescription for glasses, there are a few basic components that you can dissect it into:

  • First, there is your “distance” prescription, which is generally a grid on the top of your prescription. This grid should have two rows labeled “OD” and “OS”.
  • OD stands for right eye, and OS stands for left eye. Each eye should have spaces labeled for Sphere (or SPH), Cylinder (or CYL), and Axis. While each eye does not have to have numbers for all of these, there should be at least one number for each eye; these make up your distance prescription, or your prescription for seeing far away.
  • This distance prescription area may have “SPH” written in a Cylinder area. This means there is no cylinder, or cylinder is zero. Also, you can have sphere without cylinder or axis, but you cannot have cylinder without axis or axis without cylinder. Cylinder and axis work together.
  • The numbers for your cylinder and axis are either positive (+) or negative (-) and always have two numbers after the decimal place. In other words, if your doctor writes, “-025” for your sphere, that means “-0.25,” “+300” means “+3.00,” and so on. Axis is a number between 0 and 180 that isn’t marked positive or negative.
  • Second, there is your bifocal prescription, which should be just below your distance prescription. This is only for people who have a separate prescription for near and far viewing. This will generally be labeled as, “ADD,” “Bifocal,” or “Addition,” and it will be another number with two numbers after the decimal place, such as “+1.25.” It will ALWAYS be positive.
  • Third, there is your pupil distance. This may be in any number of places on the prescription, either at the top, in the middle, at the bottom, or on the back of the page. Sometimes the doctor does not mark it. It is typically labeled PD” or “Pupil Distance.
  • If your pupil distance is not marked on your prescription, you can often call your doctor for it or measure it yourself. PD is the distance between your pupils while you’re looking straight ahead, and it’s measured in millimeters.

These are the basic components necessary to be able to read your prescription and enter the information into a form online to order prescription glasses.

If you’re still confused about how to read your prescription for glasses, don’t feel bad. Many people contact us regularly to ask how to understand their prescription while entering it in online.

If you need more help with your glasses prescription, you can give us a call or leave a comment below. Thanks for reading, and happy shopping!

  1. Ava Fala says:

    I’m confused. I had an eye exam & they gave me my papers & said glasses prescription. It’s says my OD IS -0.75 & OS is -1.00. That’s it. No other numbers . What does that mean ?!

    • b.kotian says:

      Hi Ava Fala,

      The numbers -0.75 and -1.00 indicate the degree of nearsightedness for your right and left eyes respectively in your glasses prescription.

  2. Mia Evans says:

    It’s interesting to know that each eye doesn’t have to have numbers, but they would need to have at least one number for each eye. I can imagine how important it is to have a professional when getting prescription glasses to ensure that the right measurement would be recorded. It will give the user peace of mind that they will get the right glasses without getting headaches while wearing them in the long run.

    • SanMartin says:

      Hi Mia,

      Yes, you should always get exanimated for a professional to get your right prescription.

  3. Geri says:

    If my spherical od is pl and my os is +0.25, do I need bifocals.

    • Ryan Phillips says:

      Hi Geri,

      If you require a bifocal, it would be listed on your prescription as ADD. It sounds like the PL and the +0.25 are your sphere corrections, which indicate whether you are nearsighted or farsighted.

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