On an eyeglass or contact lens prescription:
- OD = Oculus Dexter → Right eye
- OS = Oculus Sinister → Left eye
- OU = Oculus Uterque → Both eyes
These are Latin abbreviations still commonly used by eye doctors.
You’ll usually see them in a prescription table like this:
| Term | Meaning |
|---|---|
| OD | Right eye |
| OS | Left eye |
| OU | Both eyes |
Other common prescription terms:
| Abbreviation | Meaning |
|---|---|
| SPH | Sphere power (nearsighted/farsighted correction) |
| CYL | Astigmatism correction |
| AXIS | Direction of astigmatism |
| ADD | Extra magnification for reading/progressive lenses |
| PD | Pupillary distance |
How to interpret SPH values:
- Negative number (e.g. -2.00) → Nearsightedness
- Positive number (e.g. +1.50) → Farsightedness
Example prescription:
| Eye | SPH | CYL | AXIS |
|---|---|---|---|
| OD | -2.00 | -0.75 | 180 |
| OS | -1.50 | -0.50 | 170 |
Meaning:
- Right eye is slightly more nearsighted
- Both eyes have some astigmatism
A common point of confusion:
- “Right” and “left” are from the wearer’s perspective, not someone looking at you.
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