Understand Your Prescription
Sometimes prescriptions can be confusing, so we’ll explain the most common formats. Your prescription might look like these examples:
Sphere (SPH)
Indicates the strength of your prescription. Distance prescriptions will usually have a (-) before the number. Reading prescriptions will usually have a (+) before the number. Below you can find the sphere details marked in blue.
Cylinder (CYL)
This indicates the amount of lens power for astigmatism. If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.
Axis (AXIS)
This describes the lens meridian that contains no cylinder power to correct astigmatism. The axis is defined with a number from 1 to 180. The number 90 corresponds to the vertical meridian of the eye, and the number 180 corresponds to the horizontal meridian.
Prism
Prism is prescribed to correct a muscle imbalance between the two eyes so it should help make your vision more comfortable.
ADD
magnification power for Bi-focals & progressives. The Additional Value (ADD) is commonly used for bifocal or progressive lenses as well as for reading glasses.
* It may be written in the near vision (N.V.) or “ADD” section of the prescription.
* Sometimes your doctor will write the “ADD” once - it will be equal for both eyes. Just insert the same number twice when ordering.
* If your prescription has an “ADD” and you only want single vision distance glasses - simply leave the “ADD” off of your prescription when ordering.
* If you're buying reading glasses, be sure to leave the ADD on your prescription!



Prescription Values explanations
Sphere (SPH)
Indicates the strength of your prescription. Distance prescriptions will usually have a (-) before the number. Reading prescriptions will usually have a (+) before the number. Below you can find the sphere details marked in blue.
Cylinder (CYL)
This indicates the amount of lens power for astigmatism. If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.
O.S Left Eye
Axis (AXIS)
This describes the lens meridian that contains no cylinder power to correct astigmatism. The axis is defined with a number from 1 to 180. The number 90 corresponds to the vertical meridian of the eye, and the number 180 corresponds to the horizontal meridian.
Prism
Prism is prescribed to correct a muscle imbalance between the two eyes so it should help make your vision more comfortable.
O.D Right eye.
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