Understanding Your Eyeglasses Prescription

When you get your prescription eyeglasses in North Syracuse, NY, the technician will get the prescription filled with the eyeglass frames of your choice. All you have to worry about is what kinds of frames you want and whether you want certain lens coatings or other features. Since you’ll have the prescription for about a year, it’s helpful to understand the abbreviations and numbers that appear on it.

OD and OS

These are abbreviations that derive from the Latin, meaning “oculus dexter” and “oculus sinister.” They mean right eye and left eye, respectively. If your prescription also has an abbreviation, OU, that pertains to both eyes.

Sphere, or SPH

This indicates the amount of lens power, and it’s a measurement used by the optometric lab that will be fabricating your lenses. Measured in diopters (D), if the number has a minus sign (-), it means you’re nearsighted, while a plus sign (+) indicates farsightedness.

Cylinder, or CYL

You’ll only see this if you have astigmatism. Otherwise, the field for CYL will be left blank. A minus sign means nearsighted astigmatism, while a plus sign indicates farsighted astigmatism.


The axis defines the orientation of the astigmatism; in other words, the direction the astigmatism is occurring. It will appear as a number anywhere between 0 and 180.


If you’re getting bifocals or trifocals, you’ll see this number, which is the added magnifying power applied to multifocal lenses, and it’s used to correct presbyopia. This number is always understood to be a “plus” power, even if it’s not explicitly stated.


Less common; this is a measurement used to correct alignment problems in the eyes. The number indicates the amount of power that’s used to compensate for any eye alignment issues you may have, and it’s measured in prism diopters, which may appear as “P.D.”

If all of this sounds complicated, that’s because it is. Your eye doctor works very hard to ensure the accuracy of all these measurements so you get the best possible eyeglasses. You can trust your optometrist in North Syracuse, NY when it comes to correcting your vision as much as possible. Contact us today to book your eye exam for prescription eyeglasses in North Syracuse and surrounding areas.

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