Understanding abbreviations on a glasses prescription can be confusing. Many people encounter terms like “OD” and wonder what they mean. This article clarifies “OD” and explains the various components found on an eyeglass prescription, helping individuals understand their vision correction needs.
Understanding OD, OS, and OU
“OD” on an eyeglass prescription comes from the Latin “oculus dexter,” meaning “right eye.” It indicates the vision correction measurements for your right eye. Similarly, “OS” stands for “oculus sinister,” referring to the left eye and its specific corrective needs.
These Latin abbreviations are used by eye care professionals to distinguish between the two eyes. The abbreviation “OU” may also appear, meaning “oculus uterque” or “both eyes.” This term is used when prescription values are identical for both eyes.
Decoding Your Glasses Prescription
Beyond OD and OS, an eyeglass prescription lists specific corrective powers for each eye. “Sphere,” often abbreviated as SPH, indicates the main lens power needed to correct nearsightedness or farsightedness. A negative sign before the SPH value signifies nearsightedness, meaning distant objects appear blurry, while a positive sign indicates farsightedness, where near objects may be unclear.
“Cylinder,” or CYL, specifies the lens power required to correct astigmatism, a common condition where the eye’s cornea has an irregular shape. If you do not have astigmatism, this column may be left blank or contain “SPH” or “Plano.” The “Axis” value, measured in degrees from 1 to 180, accompanies the CYL and indicates the precise orientation on the lens where the astigmatism correction should be applied.
For individuals needing help with close-up tasks, a value labeled “Add” (short for Addition) may be present. This number represents the additional magnifying power needed for reading or other near vision activities. The “Pupillary Distance” (PD) is another measurement, representing the distance in millimeters between the centers of your pupils. This measurement ensures the optical centers of your new lenses align correctly with your eyes.
The Importance of Knowing Your Prescription
Understanding the details of your glasses prescription offers several practical advantages. It enables you to accurately order new eyewear, whether from an optical store or an online retailer. Knowing the specific values for each eye helps ensure you receive lenses that precisely match your vision needs.
Familiarity with your prescription also allows for more effective communication with eye care professionals regarding changes in your vision or specific concerns. This knowledge can empower individuals to monitor their eye health and make informed decisions about their eyewear. Having the correct and up-to-date prescription is important for clear vision and can help reduce eye strain and discomfort.