How to Read Your Glasses Prescription

After you finish your eye exam, the doctor should provide you with a written prescription for corrective lenses. With all the rows and blocks of numbers and letters, it can be tough to determine exactly what each of these things means for you. An eyeglass prescription doesn't need to be confusing. If you wear glasses, it’s useful to be able to read your prescription – especially if you want to order new specs from an online retailer.

In your eye prescription, you will see numbers under different abbreviations.

In simple terms, higher the numbers, the poorer the eyesight. A plus (+) in front of the number means you are farsighted (hyperopia), and a minus (-) means you are nearsighted (myopia).

Eye prescription chart abbreviations

Look for O.D. or O.S. to determine which eye is which. Most prescriptions will include at least two rows of numbers, one labelled “O.D.” and the other labelled “O.S.” O.D. is short for “oculus dexter,” which is Latin for “right eye.” O.S. is short for “oculus sinister,” which is Latin for “left eye.”

SPH Value

SPH stands for “spherical.” The numbers in this column indicate how strong your lens must be to correct for nearsightedness or farsightedness. The numbers represent diopters, a unit of measurement used to describe the corrective strength of a lens.

• A negative number, such as -4.00, indicates nearsightedness (difficulty seeing far away).
• A positive number, like +2.50, indicates farsightedness (difficulty seeing up close).

CYL and Axis

CYL and Axis (cylinder & axis) indicate astigmatism. CYL indicates the lens power needed to correct it, and Axis the curvature of your cornea. In simple terms, the axis column contains a number that corresponds to the angle of your astigmatism.

• The numbers in the CYL column will be either positive i.e., +1.00 or negative i.e., -0.50 depending on whether your astigmatism corresponds to farsightedness or nearsightedness.

If CYL and Axis are left empty, it means that there is no astigmatism.

ADD Value

ADD values indicate the additional correction you may require for reading, which is used in progressives, reading glasses, or multifocal glasses.

Pupillary Distance

PD (Pupillary Distance) indicates the distance between the centers of your pupils. This value ensures the center of the lens is in the right place.

Progressive Glasses

Progressive lenses correct vision at all distances, completely eliminating the need to switch between reading and distance glasses throughout your day. Update: We’ve upgraded our standard option for even wider fields of view!

Nearsighted prescriptions

A nearsighted prescription will feature a number with a minus (-) symbol in the ‘sphere’ box. This means your lenses will be customize to improve your distance vision.

 

Farsighted prescriptions

A prescription for someone who is farsighted will feature a number with a plus (+) symbol in the ‘sphere’ box. This indicates that your lens should be customize to correct near vision.

 

Astigmatism prescriptions

If you have an astigmatism, you will have a number in the ‘cylinder’ column of your prescription that indicates the lens power needed to correct the astigmatism. There will also be a number in the ‘axis’ column that’s needed for astigmatism correction.

Progressive prescriptions (multifocal)

A progressive prescription will include an ADD value, sometimes marked as NV. This indicates the required strength for the near prescription in your lens.