How to Read Your Contact Lens Prescription

How to Read Your Contact Lens Prescription

Understanding your contact lens prescription might feel overwhelming, especially if you're new to wearing contact lenses. In this blog, we’ll break down the different components and guide you through the basics of reading contact lens prescriptions. By the end, you'll have the knowledge and confidence to make well-informed choices that perfectly suit your needs.

One of the first steps to understanding your contact lens prescription is knowing the common abbreviations and terminology that come with it. Often, people need specific prescriptions for each eye, so you may see different abbreviations according to the lens. Below are the most common abbreviations/terms that you will most likely see on every prescription:

  • OD: Oculus dexter, or your right eye

  • OS: Oculus sinister, or your left eye

  • SPH/PWR: These two abbreviations stand for sphere and power and are often used interchangeably. Sphere and Power describe the strength of your prescription. A positive number indicates farsightedness, while negative numbers indicate nearsightedness.

*When ordering your lenses from Blue Planet Optics, each of the abbreviations above is listed, so you can easily match them to your prescription while shopping!

  • CYL: Cylinder measures the amount of astigmatism, if present, in your eyes. This value will be listed as zero if you do not have astigmatism. 

  • DIA: The diameter value accounts for the full width of your contact lens. This number often falls in the range of 14-14.5. 

  • BC: The base curve value is always between 8 and 9. Why is this important? The base curve of your lens is important because it should align well with the curvature of your eye. Ill-fitting lenses may lead to irritation.

  • AXIS: The axis value corresponds to the orientation of the astigmatism in your eye. This value is represented in degrees and always falls between 0 and 180. 

  • ADD: This stands for addition or additional magnification. This value represents the additional power required for your vision. ADD is often listed in terms such as “Add Power” or “Extra Strength.” 

  • D/N: This stands for dominant or non-dominant eye. Sometimes, lenses have different levels of correction, so it is important to be able to differentiate the two. 

*Fun fact! We all have one dominant eye and one non-dominant eye! 

  • Multifocal lenses correct distance vision in your dominant eye, whereas your non-dominant eye is corrected for near vision. 

Provided below is an example of what a contact lens prescription may look like:

A contact lens prescription is typically valid for one to two years but can vary. Online contact lens marketplaces should not accept prescriptions that are expired. Follow up with your eye care professional regularly to ensure your prescription remains up-to-date. 

By familiarizing yourself with the key terminology and values, you can make informed decisions about your contact lenses and seek appropriate vision correction. Remember to consult your eye care professional for any further questions or concerns regarding your prescription, as they are best equipped to provide personalized guidance for your eye care needs. 

See you soon!

-Kristi Skov
Marketing Intern at Blue Planet Optics
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