Understanding Your Prescription

Making Sense of Your Glasses Prescription

So you've completed your eye exam and you now have a copy of your prescription for glasses. Trying to understand it can be confusing. It can look like a hodgepodge of strange words, abbreviations, and numbers. While it isn't necessary to earn a degree in optometry to interpret it, it's a good idea to have a general understanding. 

Fortunately, with a little explanation it will begin to make sense. The following article will provide a simple breakdown of basic terms, abbreviations, and numbers. 

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Understanding Key Terms and Numbers

The following key terms and abbreviations are found on standard glasses prescriptions, starting with the columns from left to right:

  • RX/Eye- Both terms are used interchangeably.
    • OD: This refers to your oculus dexter, or right eye, as seen from the vantage of the optometrist when he assesses you. 
    •  OS: The oculus sinister refers to the left eye.
    • OU: Oculus uterque refers to both eyes.
  • Sphere (SPH): The term used to describe the overall lens power required to correct your vision. A plus ( + ) sign refers to distance corrections for farsightedness (hyperopia),  whereas the minus ( - ) sign is for nearsightedness (myopia). Lens power is measured by diopters. Ex. In the OS row,  + 4.00 means that the left eye needs 4 diopters of correction for farsightedness.
  • Cylinder (CYL): The next column addresses the cylinder number which indicates how much eye curvature you have. Not everyone has this condition, which is also known as astigmatism. The eye shape of people with astigmatism is sometimes likened to the general shape of a football, as opposed to the basketball-shaped eyes of those with no curvature.

Common Questions

They will not. Contact lenses have a different prescription because of how they are measured (fitted) to match the precise size and diameter of your eye.
Multifocals: These feature multiple focal points in the lens for different aspects of vision, such as distance vision, intermediate, and reading. Bifocals: These types of glasses have two prescriptions in the lenses. The top part is for regular vision, and the bottom is for reading. Bifocals are also multifocal. Progressive Lenses: These are also a type of multifocal glasses with the added advantage of them not having lines separating the sections. These glasses gradually shift their functions from the top of the lens to the bottom, allowing the wearer a more harmonious integration of the different features.
Opticians are professionals who offer services such as helping patients choose glasses or contact lenses, fitting lenses into frames, and polishing and cleaning contact lenses. They cannot conduct eye exams, write prescriptions for glasses or contact lenses, or treat or diagnose eye conditions like optometrists.
Understanding Your Prescription
Dr. Zurcher cartoon

Reading Your Prescription

Understanding how to read a glasses prescription can seem daunting at first. As we have hopefully shown you in this article, once you understand the basic meaning of key terms and abbreviations, it makes a lot more sense. Always speak with your optometrist if you have any questions or concerns about your current prescription.


Such a nice optician. My grandson is only 4 and needs glasses. We were so sad, but he explained the issues, and we will follow up as he suggested.

Anna P.

I had such a good experience with the clinic. Very friendly staff and doctor, did not have to wait for long to be called, and was treated respectfully. Thanks, American Family.

June S.

Dr. Zurcher has gone above and beyond what any other eye doctor has ever done to figure out what is going on with my eyes. Very happy with American Family Vision.

Christine R.

Family Vision Clinic changed our lives! My daughter was frequently car sick, and she was getting headaches every day, often painful enough that they brought her to tears. We saw a string of doctors and therapists, but we made no progress. Finally, we found Dr. Levi Zurcher and his eye therapist Rain. After ten weeks of eye therapy my daughter no longer gets headaches, and she no longer gets car sick. Daily tears are a thing of the past. I really can’t say enough about this clinic. It was fascinating to watch Dr. Zurcher work. For the first time, someone who knew what they were doing was intently studying my daughter, really trying to figure out all of her eye issues, and his therapist Rain is one of the most patient and lovely people that I’ve ever had the good fortune to meet. We’re finished with eye therapy—yay!—and I have switched to American Family Vision Clinic for all of my family’s other eye health needs.

Lars Wulff

Very professional, yet kind and helpful. They do what they can to make the appointment comfortable. I was running a bit late, I made sure ti call. They were able to switch me with a patient who was already there, they treated me with respect, and helped my son have confidence by getting him the eye care he needed that day. Thank you so much! Would recommend to anyone. It's a blessing that they care enough to work with people who have all different types of insurance from work to state coverage.

Justin E.

The staff is friendly. The Doc is very knowledgeable. The office is family friendly and everyone is so patient with the little ones.

Amy Fagerness
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