What do OD, OS, SPH, CYL and AXIS represent on the prescription?

OD = Right eye

OS = Left eye

SPH  = Sphere: This indicates the amount of lens power, prescribed to correct farsightedness or shortsightedness.   Plus sign (+) indicates farsighted; Minus sign (–) indicates shortsightedness.

CYL = Cylinder: This indicates the amount of lens power for astigmatism. For CYL there is also a (+) or (-) sign in front of the value. If you do not have astigmatism, this value will be zero.

AXIS: This measurement is in degree and will only be mentioned if there is a CYL value or astigmatism correction required. The axis is defined with a number from 1 to 180.

PD = Pupillary distance: It is the distance between the two pupils and the measurements are in millimeters (mm).

All the information can be obtained from your optometrist or doctor. In the event where your PD is not given, you can measure it yourself. Just follow the steps in the link.

Should you require more information, please do not hesitate to drop us an email at