Key Takeaways
- Your glasses prescription is a written order from your eye doctor for your lenses.
- OD means your right eye, OS means your left eye, and OU means both eyes.
- A minus sign points to nearsightedness, and a plus sign points to farsightedness.
- Numbers further from 0 mean stronger lenses.
- A contact lens prescription is a separate document from your glasses prescription.
You leave your eye exam with a slip of paper full of letters, numbers, and plus and minus signs, and it can look like a secret code. Our team at Eyes on Westlake is always happy to walk you through it, and this guide can help you read it at home too.
Your prescription tells you which eye each number belongs to, how strong your lenses need to be, and whether you need extra help for astigmatism or close-up reading. Once you know what the letters stand for, you can bring fresh questions to your next comprehensive eye exam. You can also browse the optical boutique with a clearer idea of what your lenses need.
What Is a Glasses Prescription?
A glasses prescription is a written order from your eye doctor for your lenses. It shows up as a small grid of short letters and numbers, often with one row for each eye.
Your 2 eyes can have different numbers.
You might see well with your left eye and need a stronger lens on the right. The grid shows those differences side by side.
What Do OD, OS, and OU Mean?
These letters come from Latin, and each one tells you which eye a row belongs to. Here’s what each label means:
- OD stands for oculus dexter and means your right eye.
- OS stands for oculus sinister and means your left eye.
- OU stands for oculus uterque and means both eyes.
What Do SPH, CYL, Axis, and Add Mean?
Sphere and Your Plus or Minus Sign
The sphere (SPH) column shows the main lens power for each eye. The sign in front of the number tells you what kind of help your eyes need:
- A minus sign means you’re nearsighted, so road signs and other faraway things look blurry.
- A plus sign means you’re farsighted, so a book or your phone screen looks blurry up close.
- PL or Plano means your eye doesn’t need any sphere power.
Cylinder and Axis for Astigmatism
The cylinder (CYL) number shows the lens power used to correct astigmatism. The Axis is a degree from 1 to 180 that shows the direction of your astigmatism.
Blank CYL and Axis boxes mean you don’t have astigmatism in that eye.
Add and Prism
The Add number is extra power placed in the lower part of your lens for bifocals or progressives. It often helps with reading for people over 40, like when the print on a restaurant menu starts to look smaller.
Prism shows up less often. It can help some people with double vision.
How Strong Is Your Prescription?
What Diopters Tell You
Lens strength is measured in diopters. A 0 means your eye needs no correction, and the further your number sits from 0, the stronger your lenses get.
A higher plus number, like +4.00 compared to +2.50, means more help for close-up vision. A higher minus number, like -7.00, means more help for distance vision.
A Sample Prescription
Here’s how a full prescription might look on paper:
- The right eye, OD, has SPH -2.50, CYL -1.00, and Axis 180.
- The left eye, OS, has SPH -3.00, CYL -0.50, and Axis 90.
- An Add of +1.50 gives extra power for close-up tasks like reading.
This person is nearsighted in both eyes, with a little more power on the left. Both eyes show some astigmatism, and the Add helps with reading.
Contact Lens Prescriptions and Frame Numbers
Why Contact Lens Prescriptions Differ
Contacts sit right on your eye, so a contact lens prescription is its own document. It includes size and brand details for your lenses, and it needs a separate contact lens fitting.
What the Numbers on Your Frames Mean
Look inside the arm of your glasses, and you’ll often find a row of 3 numbers. Each one is a measurement in millimeters:
- The first number is the lens width.
- The second number is the bridge width between the lenses.
- The third number is the temple arm length.
These numbers can help you find frames with a similar fit when you shop for a new pair.
Questions to Bring to Your Eye Doctor in Westlake
Your appointment is a great time to talk through your numbers. These questions can help you get clear answers:
- Ask what each number means for your family’s vision.
- Ask what changed between your old and new prescriptions.
- Ask how your Add or astigmatism numbers affect your lens choices.
Your optometrist in Westlake can explain each number in plain, simple terms. You and your kids can leave the office feeling informed, not puzzled.
Visit an Optometrist in Westlake for Your Family’s Eye Care
Your prescription is a short set of instructions for your lenses, and now you know how to read it. At Eyes on Westlake, Dr. Blythe McPherson and our team take time to answer your questions in a way that’s easy to follow, whether it’s your own exam or your child’s first visit.
Once you have your numbers, you can explore quality eyewear and handcrafted frames in the calm, welcoming optical boutique. Book your family’s next eye exam with Eyes on Westlake today and see your prescription come to life in a pair you love.
