How to Read Your Prescription
Your prescription is a small grid of numbers and abbreviations. Once you know what each cell means, you can order glasses online from anywhere with confidence. Here's the entire vocabulary in plain language.
| SPH | CYL | AXIS | ADD | PD | |
|---|---|---|---|---|---|
| OD (right) | −2.25 | −0.75 | 180 | +1.50 | 62 |
| OS (left) | −2.50 | −0.50 | 175 | +1.50 |
OD (oculus dexter) is your right eye. OS (oculus sinister) is your left eye. Some prescriptions just write "R" and "L". Every line applies to that specific eye. The two eyes often differ.
The strength of the lens that corrects nearsightedness (negative numbers, e.g. −2.25) or farsightedness (positive, e.g. +1.75). Measured in diopters. The further from 0, the stronger the correction.
If the cornea is not perfectly spherical, this can result in astigmatism, a common, harmless, and easily correctable condition. CYL indicates the strength of the cylindrical lens needed to correct it and is usually paired with AXIS. If both CYL and AXIS are left blank on your prescription, no astigmatism correction is required.
A number between 1 and 180 that indicates the orientation of the cylindrical correction. It tells the lab the angle at which the CYL correction should be positioned. AXIS is only required when a CYL value is prescribed.
A positive number (e.g. +1.50) added to your distance prescription to provide the additional power needed for the reading portion of bifocal or progressive lenses. It is commonly prescribed for people over 40 and is typically the same for both eyes.
The distance in millimeters between the centers of your two pupils. Lets the lab center the optical zone of each lens directly in front of each eye. Adult range 54–74 mm. Critical for online orders.
Rare. Used when your eyes have trouble aligning. Comes with a direction (BU/BD/BI/BO). If your prescription has no PRISM column, you can ignore it. Most people don't need it.
How Recent Should Your Prescription Be?
A one-year-old prescription is often still usable, but it depends on whether your vision has changed. Adults with stable vision can usually rely on a prescription for one to two years. Children, teens, and anyone with changing vision may need an exam more often.
Consider a fresh eye exam if you notice any of these
- More blurry vision
- Headaches or eye strain
- Squinting more often
- Trouble driving at night
- Dizziness with your glasses
- Difficulty reading or focusing
Upload Your Prescription
On any product page, click "Buy Glasses + Free Thin Lenses" to enter the SPH, CYL, AXIS, and PD values from your prescription, or upload a clear photo of it. Online orders are available for Single Vision lenses only, not for Progressive or Prism lenses. Your lenses are cut and quality-checked within 1–5 business days before shipping, subject to stock availability.
Don't have a prescription? Get a free eye refraction test at any of our stores, no appointment needed. A full written prescription is provided with proof of purchase.