How to read and understand your eye prescription

 Understanding Your Eye Glasses Prescription

As we all know, getting an eye glasses prescription is a crucial step in ensuring clear vision and overall eye health. But when you receive your prescription from your eye doctor, it can be overwhelming to decipher all the numbers, abbreviations and terms. In this guide, we will break down every aspect of your prescription and help you understand what each measurement means.

OD vs OS

The first thing you’ll notice on your prescription are the abbreviations OD and OS. These stand for “oculus dexter” (right eye) and “oculus sinister” (left eye) respectively. This is simply to differentiate between the measurements for each eye.

Sphere (SPH)

The sphere measurement on your prescription indicates the amount of lens power needed to correct your vision. If you have a minus sign (-) in this section, it means you are nearsighted and require lenses for distance vision. A plus sign (+) indicates farsightedness and the need for lenses to improve close-up vision.

Cylinder (CYL)

Cylinder measures the level of astigmatism present in your eyes. This is a common condition where the cornea is not perfectly shaped, resulting in blurred or distorted vision. The number in this section indicates how much correction is needed for astigmatism.

Axis

The axis measurement works hand-in-hand with cylinder and  indicates the direction of the astigmatism. This number ranges from 0 to 180 degrees and helps your optometrist determine the correct placement for the lens.

Addition (ADD)

If you are over the age of 40, you may see an “ADD” measurement on your prescription. This is used to correct presbyopia, a condition where the eye loses its ability to focus on close objects. The higher this number, the more correction is needed for near vision.  

H Prism and V Prism

Prism measurements are used for individuals with muscle imbalances in their eyes, causing double vision or eye strain. The “H” stands for horizontal prism and the “V” for vertical prism. These measurements help determine the amount of movement needed to align both eyes.

V base and H base

These measurements refer to the placement of the prism on the lenses. “H” stands for horizontal base and “V” for vertical base. These are important for ensuring the correct orientation of the lenses when they are made.

Pupillary Distance (PD)

Your PD is an important measurement that determines how far apart your eyes are in order to properly center your lenses. This is usually measured in millimeters and can be done by your optometrist or at home using a ruler and mirror.

  

Pupil Distance (PD)

The pupil distance measurement is simply the distance between your pupils in millimeters. This is important information for accurately fitting your lenses to your face and ensuring proper vision correction.

Understanding Your Prescription

It’s important to understand that each prescription is unique to an individual's eyes and may vary from person to person. Your optometrist will take into account various factors such as your current visual

Prism

Prism measurements are written in prism diopters (p.d.) and are used to correct eye alignment issues such as double vision or lazy eye. This is often indicated with a base direction (up, down, in or out) and a number denoting the strength of the prism.

Pupillary Distance (PD)

The pupillary distance is the measurement between your pupils and helps ensure that your lenses are properly aligned with your eyes. This measurement may not always be included on your prescription as it can also be measured by an optician during the fitting process.

Additional Notes

Your prescription may also include additional notes or abbreviations such as "NV" for near vision only, "Plano" to indicate no correction needed, or "OU" for both eyes. It's important to discuss any questions or concerns about these notes with your eye care professional.

In addition to understanding the numbers and measurements on your prescription, it's important to also communicate any specific vision needs or concerns with your eye care professional. They can work with you to find the best eyewear solution for your individual needs and lifestyle. Remember to also regularly schedule comprehensive eye exams to monitor any changes in your vision and update your prescription as needed. Your eyes are a valuable asset, so make sure to take care of them by following proper eyewear recommendations and maintaining regular eye health check-ups.  So, don't hesitate to reach out to your optometrist if you have any questions or concerns about your prescription or vision. They are there to help you maintain healthy eyes and clear vision.   

 

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