How to Read Your Eye Prescription

You’ve gone to the optometrist,  had your eye exam, and now it’s time to get your prescription. When you look at it, though, you’re perplexed—what do all these letters and numbers mean? How do they tell you what kind of glasses you should get?

Eye Prescription Abbreviations

OD: Your right eye. OD stands for oculus dexter, which is “right eye” in Latin. 

OS: Your left eye. OS stands for oculus sinister, which is “left eye” in Latin. 

NV: Near vision (seeing things close-up).

DV: Distance vision (seeing things far away).

PD: Pupillary distance. It is the distance between the centers of your pupils. It is measured in millimeters. The measurement ensures that when you get your glasses, you are looking through the right spot in your lenses. It is possible to take this measurement on your own if your eye care professional does not provide it. The average number is 62mm for women and 64mm for men. However, it can range from 58 to 68mm;

Diopters: Any numbers you see in the “Sphere” or “Cyl” column of your eye prescription stand for diopters.  diopters measure the refractive power of a lens. 

SPH: Sphere. It describes the amount of lens measured in diopters needed for good vision. The term means that the correction for your sight is spherical. If you are shortsighted, the number under the abbreviation will include a (-) sign. The number will have a (+) sign if you are long-sighted. If your prescription has the word Plano, PI, or an infinity sign, it means that you do not have distance problems. You may, however, have astigmatism. Most values will be 0.00 to +/-20.00.

CYL : Cylinder. It represents the amount of lens power you need for astigmatism. If you do not have astigmatism, you may not have anything indicated in this column. The value may be a plus or a minus, and in most cases, the value will be between +/-0.25 to +/-4.00.

AXIS:  Axis is the lens meridian that has no cylinder power to correct astigmatism. The axis number helps your eye care professional know the direction in which they should position a cylindrical power in the lenses of your glass. For example, the number may be between 1 and 180, where 90 represents the vertical position while 180 represents the horizontal one. The numbers only describe the position of astigmatism; they do not explain the strength of your prescription. The Axis can be present if there is a CYL value.

ADD: Add stands for Addition. It stands for the additional correction that you need for reading. It is used in bifocal glasses, reading glasses, or varifocal glasses. It represents the additional power over the distance prescription. It only appears once in your prescription because the additional power is the same for both eyes. The value is typically between +0.50 to +3.50. 

Negative Numbers: If you see a minus sign in front of a number, that indicates nearsightedness, or myopia. 

Positive Numbers: If you see a plus sign in front of a number, that indicates diopters that will correct hyperopia. 

Prism –A prism corrects lazy eyes. In addition, it may correct mild conditions, including particular eye disorders and conditions that need the image in focus to change its position. A prism is measured in Prism Dioptre. They come with directions such as UP, DOWN, IN, and OUT. The value may go up to ten.