How To Read Your Prescription

Staring at your prescription and seeing a grid of confusing numbers and abbreviations? Don't worry, you are not alone. While it looks like a secret code, reading your prescription is actually quite straightforward once you know the key terms.

Here is a simple breakdown to help you enter your details correctly and order your perfect pair of glasses.

The Latin Abbreviations: OD vs. OS

First, let’s identify which eye is which. Doctors use Latin abbreviations:

  • OD (Oculus Dexter): This is your Right Eye.

  • OS (Oculus Sinister): This is your Left Eye.

  • OU (Oculus Uterque): This means Both Eyes.

Decoding the Numbers

Your prescription is usually divided into a few key columns. Here is what they mean:

1. SPH (Sphere)

This indicates the strength of your lens power to correct nearsightedness or farsightedness.

  • (-) Minus Sign: You are Nearsighted (you have trouble seeing things far away). Example: -1.25.

  • (+) Plus Sign: You are Farsighted (you have trouble seeing things close up). Example: +2.50.

  • Note: The further the number is from zero, the stronger the prescription.

2. CYL (Cylinder)

This number indicates the amount of Astigmatism (shaped like a football rather than a basketball).

  • If this column is blank, you do not have astigmatism.

  • If there is a number, it will also have a minus (-) or plus (+) sign.

3. Axis

If you have a number in the CYL column, you must have an Axis number.

  • The Axis is a number between 1 and 180.

  • It tells the lab exactly where to position the astigmatism correction on your lens.

  • Note: This is not a measure of strength, just an angle.

4. ADD (Addition)

This is primarily for Bifocals or Progressive lenses.

  • It indicates the added magnifying power needed for reading.

  • It is almost always a positive (+) number (e.g., +1.75).

  • Note: If you are ordering "Single Vision" glasses for distance only, you can usually ignore this.

⚠️ Common Mistakes to Avoid

  • Confusing Plus (+) and Minus (-): A -2.00 is very different from a +2.00. Please double-check the signs before entering them!

  • Mixing up OD and OS: Ensure you enter the Right Eye numbers in the Right Eye field.

Still unsure? You can simply upload a photo of your prescription at checkout, and our opticians will take care of the rest!