An eyeglass prescription is a short table of numbers. Once you know the abbreviations, entering it online is simple.
| Term | Meaning |
|---|---|
| OD | Oculus dexter — your right eye |
| OS | Oculus sinister — your left eye |
| OU | Both eyes |
| SPH (sphere) | Main lens power in dioptres. Minus for nearsightedness, plus for farsightedness. |
| CYL (cylinder) | Extra power for astigmatism. Can be blank if none. |
| AXIS | Orientation of the cylinder, from 1 to 180 degrees. Only present when CYL is present. |
| ADD | Additional magnifying power for reading, used in progressive, bifocal and reading lenses. |
| PD | Pupillary distance in millimetres. |
| Prism / Base | Corrects eye alignment. Only some prescriptions include it. |
Things to check
- Values usually move in steps of 0.25.
- Note whether each value is positive (+) or negative (−). The sign matters.
- Check the expiry date. Many regions require a current prescription.
- A contact lens prescription is different from a glasses prescription and cannot be used for glasses.
We cannot interpret or change a prescription. If anything is unclear, contact the professional who issued it.
See how lenses are matched to your prescription.
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