Learning how to read and understand your eye prescription is critical. The symbols, numbers and abbreviations you get after a vision test can help you determine whether you are farsighted, nearsighted or have astigmatism — and to what degree. Having an accurate prescription can help you choose effective eyeglasses to correct your vision and ensure comfort.
In this guide, we'll discuss how to read your eye prescription, the differences between contact lens and eyeglass prescriptions and how to explore the full scope of your vision health.
Understanding the Basics of Eye Prescriptions
Whether on paper or digital, your eye prescription often looks like a chart or grid with rows, columns and cells. It will have a mix of abbreviations, positive and negative numbers and symbols. Knowing their meaning can help you make sense of your prescription and get the right eyeglasses for your vision needs.
Prescription Symbols and Their Meanings
Eye prescriptions include specific symptoms and abbreviations indicating the parameters of corrective lenses required for each eye. Common symbols include:
- OD: Short for “oculus dexter," the Latin phrase means “right eye.”
- OS: This stands for the Latin “oculus sinister,” meaning “left eye.”
- OU: Short for “oculus uterque,” which means “both eyes.”
- Sphere (SPH): This abbreviation indicates the amount of power needed to correct nearsightedness or farsightedness.
- Cylinder (CYL): This specifies the amount of lens power to correct astigmatism, with the number indicating the degree of correction needed.
- Axis: This indicates the orientation of the astigmatism correction, measured in degrees from one to 180.
- Prism: If present, prism indicates the amount of power needed to correct eye alignment problems.
- Base: The base refers to the direction of the base of the prism, typically noted as “in,” “out,” “up,” or “down.”
- NV (N): This abbreviation includes Near Vision, the power needed for near vision in multifocal prescriptions.
- DV (D): This letter represents Distance Vision or the power needed for distant vision in multifocal prescriptions.
Understanding Prescriptions: Sphere (SPH), Cylinder (CYL), and Axis
Sphere, cylinder and axis values are important for accurately correcting vision issues like nearsightedness, farsightedness and astigmatism.
- Sphere: Sphere (SPH) on your prescription denotes the right power you need to see correctly. A minus symbol (-) beside this abbreviation means you are nearsighted, while a plus (+) symbol refers to a prescription for correcting farsightedness.
- Cylinder: The cylinder (CYL) number indicates the lens power required to correct astigmatism. The higher the number, the more significant the astigmatism. A blank column means you do not have astigmatism.
- Axis: You'll also see an axis number if you have an astigmatism, denoting the angle of the lens needed without a cylinder power to correct the astigmatism.
Prescription Scale and Numbers Explained
Your prescription's scale and numbers are critical in specifying the type and amount of corrective lenses needed to optimize your vision.
Diopters (D): Diopters (D) measure the refractive power of the lens needed to correct your vision.
- Positive values: Positive values indicate hyperopia, or farsightedness. For example, let's say your prescription reads OD +1.50 SPH and OS +2.00 SPH. This would mean both eyes have farsightedness, with the right eye needing a +1.50 diopter correction and the left eye needing a +2.00 diopter correction.
- Negative values: A minus sign indicates nearsightedness — or myopia. For example, a prescription of -2.00 SPH for the right eye and -2.50 for the left would mean you have nearsightedness in both eyes. The right eye requires a -2.00 diopter correction, and the left eye needs a -2.50 diopter correction.
Other Abbreviations Used in Eye Prescriptions
You might see additional abbreviations on your prescription, such as:
- Intermediate (INT): For multifocal prescriptions, this abbreviation specifies the power needed for intermediate vision, typically computer use.
- Pupillprescriptioary Distance (PD): The PD is the distance between the centers of your pupils. The number — measured in millimeters — ensures the optical centers of the lenses correctly align with your eyes to provide the most accurate vision possible.
- Addition (ADD): This abbreviation denotes the additional magnifying power required for the reading portion of the lens in multifocal prescriptions like progressive or bifocal lenses.
How to Read Your Own Eyeglass Prescription
The following step-by-step guide can help you understand your prescription easier:
- Identify eye measurements: Look for OD, OS and OU labels to distinguish between the key eye measurements.
- Locate sphere, cylinder and axis: Note the Sphere value for nearsightedness — the minus symbol, and for farsightedness — the plus symbol. Also, take note of the Cylinder value for astigmatism correction and the Axis value for the orientation of the astigmatism correction.
- Interpret additional values: Check for additional values like Add, Prism or PD. You can use your PD measurement to ensure your glasses are clear and comfortable for your eyes.
- Understand the prescription format: Your prescription format will usually include OS and OD values for each eye, alongside the necessary corrections for up close, faraway or intermediate vision.
- Consult with an eye care professional: If you have trouble understanding your prescription, consult with an eye care provider for clarification.
Based on your prescription, you can choose the right frames and lenses to meet your needs and lifestyle. If you feel like your prescription is incorrect or you're experiencing vision changes or discomfort, reach out to your eye care provider.
Get Started With Eyemart Express Today
Understanding your eye prescription can help you get the correct and accurate eyewear while ensuring your comfort. Start your journey to a better vision with Eyemart Express. We are committed to affordable, quality eyewear and vision health, offering over 2,000 frames and eyeglasses prepared as quickly and carefully as possible.
Stop by for an eye exam, or browse our frames online or in person. We've partnered with optical experts across the country to ensure you get the correct prescription and fit no matter where you live. Whether you need a prescription update or you're getting glasses for the first time, our eye exams serve to help you experience every moment with clear vision.
Find an Eyemart Express near you or browse our frames online today.
