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How do I read my prescription?


Do you ever feel like your glasses prescription looks like a different language? To most people it does, but in fact, these numbers are very important and explain a lot about how your eyes see the world around you. 

Whether you are nearsighted, farsighted, have astigmatism or need bifocals, your prescription is unique and made just for your eyes.

The first terms you should see on your prescription are OD and OS. These are abbreviations for the Latin terms oculus dexter and oculus sinister, which mean right eye and left eye, respectively.


Farsighted means that your OD or OS prescription has a positive power (i.e. +4.00), this means you can see objects far away but not close up. 

Nearsighted means that your OD or OS prescription has a negative power (i.e. -4.00), this means you can see objects close up but not far away.

The larger the number, the stronger your prescription power is. 

Some people have identical OD and OS powers while other people can have different powers for each eye. These eye conditions are extremely common. 

Other terms you may see on your glasses prescription may include the following: 

Sphere (SPH). This number indicates the amount of lens power measured in diopters (D), prescribed to correct your nearsightedness or farsightedness. 

Cylinder (CYL). This number indicates the amount of lens power for astigmatism. If nothing is listed in this column, it means you either have no astigmatism or that your astigmatism is so slight that you do not need a corrective lens to fix it.

AXIS. This number describes the lens meridian that contains no cylinder power to correct your astigmatism. The axis is defined with a number from 1-180 and 90 corresponds to the vertical meridian, while 180 corresponds to the horizontal meridian.  

ADD. This number is the added magnifying power applied to the bottom part of multifocal lenses to correct presbyopia. The number that appears in this section is always positive, even if it is not preceded by a plus sign. ADD will generally range from +0.75 to +3.00 D and it will be the same power for both eyes. 

Pupillary Distance (PD). This number measures the distance in between your 2 pupils in millimeters.

For more information on how to read your prescription, check out our helpful video.