What Does Near Addition Mean On Glasses Prescription

What Does Near Addition Mean On Glasses Prescription 1

What Do The Values On Your Prescription Mean?

The values that appear in your glasses prescription are classified as SPH, CYL, AXIS, and occasionally as ADD, PRISM, & BASE

SPH (Sphere)

It is a value that represents the nearsightedness (-) or farsightedness (+) of a person in 0.25 steps.

Whenever no correction for SPH is needed, the optometrist will write “Plano”, “∞”, “0.00” or just leave the space blank.

CYL (Cylinder)

If you suffer from astigmatism, you will also have a corresponding “AXIS” value (see below). CYL is a value that represents a plus or minus 0.25 steps.

It is common for opticians to leave the box blank when astigmatism correction is not required. They may also abbreviate the box with the abbreviation “DS” (Dioptre Spheres).


In your prescription, you will find an AXIS value if a CYL value is also present for that eye. The AXIS value is a number between 0 and 180 that is used to correctly orient the cylinder correction when making your eyewear.


In addition to being called ADD, it is also known as a “Near Addition” or “Reading Addition” and is always a “+” value in 0.25 steps, and refers to the amount of magnification needed to correct your near vision in comparison to the “SPH” value in your distance prescription.

A value called INTER ADD may also be used for tasks such as reading music or operating a computer from a distance.


A prism can be a metric or fraction value, for example, “1.5” or 112. A prism should also be accompanied by a directional value.


Base refers to the direction of a PRISM value, and it will only be displayed if the prescription includes a PRISM value. It is displayed as BU, BD, BI, IN or BO, depending on the direction of PRISM.

Common Abbreviations That Appear on Your Prescription.

  • OD / R: Oculus Dexter, or Right Eye

  • OS / L: Oculus Sinister, or Left Eye

  • SPH: Spherical, indicating nearsightedness or farsightedness

  • CYL: Cylindrical, indicating astigmatism

  • AXIS: Angle of astigmatism, in degrees

  • ADD: Added magnification for reading prescriptions

  • PD: Pupillary Distance, distance between your pupils

Variations to Note:

  • In some prescriptions, “R” is used to indicate the right eye and “L” for the left eye instead of “OD” and “OS”.

  • When reading prescriptions, the term “NV” or “Near Vision” may be used rather than “ADD”.

  • There is a possibility that your prescription will not contain CYL and AXIS values if you do not have astigmatism.

  • An eye alignment issue may be corrected with a prism value included in some prescriptions.

You should contact your optometrist or the professional who provided you with your prescription if you are still unsure about any aspect of your prescription.