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How To Read an Eyeglass Prescription

So, you’ve been to your eye doctor and received your prescription via a piece of paper with a variety of seemingly foreign numbers and letters scribbled on it. And, you may be wondering: What do they all mean?

Here, we decipher the array of characters for you, helping you to learn just how to read an eyeglass prescription — and pinpoint the important numbers you need to know when discussing your eyewear choice with your optician.


The Components of an Eyeglass Prescription

Your prescription will be written on a piece of paper with your doctor’s name and address printed on it plus your name and the prescription’s expiration date (typically one or two years from the date of your exam). Your doctor’s signature will also appear at the bottom.


Now, for all those characters in between:

OD vs. OS

These are abbreviations for oculus dexter and oculus sinister, which are Latin terms for right eye and left eye.



This indicates the amount of lens power correction required for nearsightedness—noted with a minus (-) sign—or farsightedness—noted with a plus (+) sign.



This indicates the amount of lens power required to correct an astigmatism (if you have one) that is cylinder shaped.



This indicates the amount of lens power required to correct an astigmatism (if you have one) that is spherical.



If you have presbyopia (requiring correction for reading), this is the added magnifying power required.



This is the amount of prismatic power required to correct eye alignment problems. Base can also be noted with Prism; it is the location of the thickest edge of the prism.


How is a Contact Lens Prescription Different?

Your eyeglass prescription can only be used for the purchase of eyeglasses. A contact lens prescription, which is also written by your doctor, will contain additional information—such as base curve, lens diameter, and the specific brand and maker of the contact lens.

In addition, instead of OD and OS, some eye-care providers use RE (right eye) and LE (left eye) for contact lens prescriptions.