The first thing you need is a copy of your valid prescription. Most written prescriptions follow a specific format which will look something like this:
Each prescription will have a left and right value for the correction of your vision within the following boxes:
"SPH" (sphere). The correction for long or short sightedness.
"CYL" (cylindrical). The correction for an Astigmatism.
"AXIS" The axis that the correction for the Astigmatism needs to be set at.
SPH (spherical) will consist of a + or – power in 0.25 steps. EG, -0.25, -0.50, -0.75, -1.00, -1.25 and so on..
CYL (cylindrical) may consist of a + or – power in 0.25 steps. EG, -0.25, -0.50, -0.75, -1.00, -1.25 and so on..
Axis will consist of a numerical value from 0 to 180, BUT, only when you have a CYL value.
Note: Usually opticians will write the "-" sign above the value and the "+" sign next to the value.
Sometimes an Add or Addition, always "+" value is included for us to decipher your reading prescription, but only if you require glasses for both distance and for reading. ADD / Addition Will only consist of a + value as is it is what it says on the tin, an "addition". We add this value to your distance prescription if you need reading glasses as well as distance or for bifocals.
