How to Read a Prescription for Contact Lenses

 Read your contact lens prescription to know exactly what you're wearing. In order to wear contact lenses you must first obtain a prescription from your eye doctor. If you are an eyeglasses wearer switching to contacts, you are probably accustomed to seeing your prescription written a certain way. Contact lens prescriptions, however, appear different from what you are used to and will contain some abbreviations that are unfamiliar. In addition, according to Oregon Health and Science University, because they are worn on your eyes, the correction will likely be different from the one you may have seen for your glasses.

Difficulty:Moderately Easy1
Look at the "OD" and "OS" on your prescription. The OD is an abbreviation for oculus dexter, which means right eye in Latin. All of the information that is written in this column or row will pertain to the right eye. The letters OS will appear either in the column beside the OD or in the row beneath it. The OS stands for oculus sinister, or the left eye. As with the right eye, all of the information that is written following the OS will be for that eye.
2
Go to the word "Power" or "Pwr". Read the numbers in this section for each eye. This is the degree of correction for the contacts. If you are hyperopic, or farsighted, there will be a plus symbol in front of this number. If you are nearsighted, or myopic, there will be a minus symbol. For example, the power on your prescription may read +1.75 if you are hyperopic or -1.75 if you are myopic.
3
Move to the section that reads "Cyl" or "Cylinder". These numbers indicate the astigmatism correction, and it will be filled in only if you have astigmatism. The plus symbol indicates hyperopic astigmatism, while the minus means myopic astigmatism.
4
Read the number that is written under "Axis". This number relates directly to the cylinder and signifies the orientation of the cylinder correction.
5
Look for the letters "BC" or "Base Curve". The BC indicates the measurement for the inner curve of the contact lenses for each eye. For example, a base curve measurement might be written on the prescription as 8.6.
6
Read the "Diameter" or "Dia" number. The diameter of the contact lenses is the actual size or width of the lens. The wrong diameter can result in a contact lens that is too big or too small for your eye. An example of a diameter measurement is 14.0.
7
Go to the space for "Brand" to read what brand of contact lens your doctor is prescribing. Although there are many different name brands for contact lenses, the names of some of the brands may end with the word "Toric" to indicate that they are for astigmatism. Other brands may end with some notation or abbreviation, such as 1-Day or EW for extended wear, to indicate how long they can be worn before they are replaced.
If the letters "PL" are written for power there is neither near or farsighted correction needed. In some cases you may have "PL" power, but still have an astigmatism correction.
Some prescriptions for contact lenses will include an "Add". This is meant for bifocal contacts and it indicates the level of reading correction that is needed. If you do not need bifocals this will be left blank.