Eyeglasses Prescription Primer

So you’ve gone to the eye doctor to make sure you’ve taken advantage of your flexible spending account (FSA) funds before the end of the year, and she’s given you a prescription for eyeglasses—now what? That piece of paper she handed you says a lot about your eyes, but can you read it? Today we’re going to go over the basics of how to read an eyeglass prescription to help you better understand what it says.

The Basics

An eyeglass prescription is unique, and can be uniquely hard to read as a result. Understanding the abbreviations and numbers will help you make sense of your doctor’s prescription.

  • The Latin abbreviation OD stands for “oculus dextrus” and OS for “ocular sinister”, which mean right eye and left eye, respectively; if you see a notation for OU (oculus unitas), it indicates something involving both eyes.
  • C” or cylinder refers to astigmatism. Astigmatism occurs when light is not focused evenly on the retina, causing blurring or distorted vision. The number in this section of your prescription can be either positive or negative.
  • The axis is measured between 0 and 180 degrees, and describes the orientation of the astigmatism for that eye.
  • S” or sphere refers to the degree of near- or farsightedness as indicated by the “OD” and “OS” portion of the prescription; a minus sign in front of the OD or OS indicates nearsightedness, a plus sign indicates farsightedness.
  • Pupillary distance (PD) measures the distance between the centers of the pupil in each eye, making it a critical measurement for preparing and making your prescription eyeglasses.

More Vocabulary

When we use the term farsighted we mean someone who has trouble seeing things up close, and sees things better at a distance; nearsighted means someone who has trouble seeing things at a distance, but sees well up-close.

When you have astigmatism, your vision is blurred or distorted due to an unsymmetrical cornea or lens, which interfere with your eye’s ability to focus properly.

Eye Chart


Make sure your eyeglass prescription is up-to-date—and that you’ve taken advantage of your FSA funds—before the end of the year! We accept CareCredit! Stop in to either Eye Elegance location, and don’t forget to connect with us on Facebook, Twitter, Instagram, Google+, Pinterest, and YouTube.




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