How to read your eye prescription
SPH, CYL, AXIS and ADD, explained in plain language β and exactly what to send us.
A prescription looks like a code, but you only need four numbers to order lenses.
OD and OS
OD is your right eye, OS your left. Some clinics write R and L instead.
SPH (sphere)
The main strength. A minus number means short-sighted (distance is blurry); a plus number means long-sighted (close work is blurry). It is measured in dioptres, in steps of 0.25.
CYL and AXIS
These two go together and only appear if you have astigmatism. CYL is how much correction is needed, AXIS is the angle it sits at, from 1 to 180. If one is filled in, we need both.
ADD
Extra power for reading, used in bifocal and progressive lenses. If your prescription has an ADD value, tell us β the lens is made differently.
PD (pupillary distance)
The distance between your pupils in millimetres. It is not always printed on the prescription, but it is what centres the lens correctly. Ask your optician, or measure it with a ruler in a mirror.
What to send us
A photo of the prescription is easiest. If you are typing it, send it like this: R -1.75 / L -2.00, PD 62. We confirm every prescription by phone before any lens is cut.
