If you recently had a vision exam and received a prescription for eyeglasses from your doctor, it may be difficult to read. While it might look like gibberish now, this cryptic mixture of numbers and letters represents important details that will ensure your prescription is filled accurately. You can learn more about the different terms included in your prescription from the guide below. 

Eyeglasses Prescriptions: Terms to Know 

OD, OS & OU 

As you scan your prescription, you may notice the letters “OD” and “OS.” These stand for oculus dexter and oculus sinister, latin names which refer to the right and left eye. These names explain what type of adjustments you will need for each lens. If you see “OU” on your prescription, this indicates both eyes. In some cases, your eye doctor may use the modernized version, “RE,” “LE,” and “BE” to indicate the right eye, left eye, and both eyes. 

SPH & CYL

You will also see the term “SPH,” which refers to the power of the prescribed lens. SPH is measured in diopters and indicates common eye conditions like near and farsightedness. A minus sign in this section will mean you are nearsighted, while a plus sign indicates you are farsighted. The higher the number, the more help you will need to see.

The cylinder (CYL) section of the prescription indicates whether the lens needs to correct astigmatism. If you have a number in this section, you have been diagnosed with the condition. The absence of a number means no correction is needed. 

Add & Prism 

“Add” means you have multifocal lenses, so the magnification type for the bottom of the lens is indicated here. “Prism” expresses the prismatic power of each lens, which helps with eye alignment. In the prism section, you will see “BU,” “BD,” “BI,” and “BO,” which refers to base up, base down, base in, and base out. These terms provide the correct fit for the eyeglasses, whether you need them moved closer to your ears or nearer to your nose. 

By memorizing the key terms in your order, you will be more knowledgeable about your glasses and eye health. The Whitefish Eye Center diagnoses eye conditions, provides prescription glasses, and helps patients understand their prescriptions. To make an appointment for an eye exam or prescription eyeglasses, call their office in Whitefish, MT, at (406) 862-2020. You can also learn more about their services by visiting their website. For eye care tips, follow them on Facebook.