Prescription Parameters Values
What are the Prescription values mean?
For each eye you need values for some or all of the following prescription parameters:
Sphere (SPH)
Represents the strength of each eye (in diopters)
-
Plus (+) values used for farsighted
-
Minus (-) value used for nearsighted
Cylinder (CYL)
Represents strength of astigmatism
Axis (AX)
When you have Cylinder (CYL) you must have Axis indicating the location of sphere and cylinder powers
Near Addition (ADD)
Represents additional refractive power to be combined to the distance power to achieve the ideal near power
Pupillary Distance (PD)
Represents the distance between pupil centers
Ocular Centre Height
Represents the vertical positioning of pupils behind each of their respective lenses.
Additional terminology you may see at typical prescription
-
OD (oculus dexterous) - simply indicates right eye
-
OS (oculus sinister) - simply indicates left right
For further reading you can visit Wikipedia