How to Read Your Eyeglass Prescription
Your prescription looks like a table of numbers, but each one has a simple meaning. Once you know them, ordering glasses online is easy.
OD and OS
OD (oculus dexter) is your right eye. OS (oculus sinister) is your left eye. Some prescriptions say RE and LE instead. OU means both eyes.
SPH (sphere)
The main power of the lens. A minus sign (−) means you are nearsighted: you see well up close but blurry far away. A plus sign (+) means you are farsighted.
CYL and AXIS
CYL corrects astigmatism, an uneven curve of the eye. AXIS (a number from 1 to 180) tells the lab the direction of that correction. If CYL is empty, you have no astigmatism and AXIS is not needed.
ADD
Extra power for reading, usually from +0.75 to +3.00. It appears when you need bifocals or progressives, often after age 40.
PD (pupillary distance)
The distance in millimeters between the centers of your pupils, for example 63. It centers the lenses in front of your eyes. Sometimes it is written as two numbers, one per eye (31.5 / 31.5).
Example
OD: SPH −2.25, CYL −0.50, AXIS 180
OS: SPH −2.00, CYL −0.75, AXIS 175
PD: 63
This person is nearsighted in both eyes with mild astigmatism, and needs single-vision lenses.
Frequently asked questions
Is my contact lens prescription the same?
No. Contact lens prescriptions include other measurements and can have different powers. Use a glasses prescription.
What if my prescription has no PD?
Many do not include it. You can measure it at home; see our PD guide.
What does "plano" or "PL" mean?
It means zero power for that value: no correction needed.
Related guides
This guide is for information only and does not replace an eye exam. If you have eye pain, sudden vision loss or flashes of light, see a doctor right away.