Decode Your Vision: How to Read Your Glasses Prescription like a Pro!

Your vision is as unique as you are, and understanding your glasses prescription is the key to achieving crystal-clear clarity. If those numbers and symbols on your prescription have always seemed like hieroglyphics, fear not! In this guide, we’ll walk you through the secrets of decoding your glasses prescription like a pro, so you can choose the perfect eyewear for your eyes. Let’s dive in!

1. Understanding the Basics: First things first, let’s break down the components of your glasses prescription. It usually consists of two main parts: the prescription for your Right eye (OD) and your Left eye (OS).

2. Sphere (SPH): The sphere measures the overall lens power needed to correct your vision. A negative (-) value indicates nearsightedness, while a positive (+) value signifies farsightedness. For example:

  • OD: -2.50
  • OS: +1.75
  • Nearsightedness: You can only see things up close (-)
  • Farsightedness: You can see far away, but have trouble seeing up close (+)
-Illustration courtesy of Essilor International-

3. Cylinder (CYL) and Axis: These parameters apply if you have astigmatism, which means your eye’s curvature is irregular or slighty ovalish instead of round. The cylinder indicates the additional power required to correct astigmatism, while the axis denotes the orientation (places the angle) of the cylinder. For example:

  • OD: -1.25 CYL @ 180 Axis
  • OS: -0.75 CYL @ 70 Axis

Eye Exam Tips:

  • If your doctor verifies you do not have an Astigmatism then there will be no numbers written under Cyl or Axis.
  • If your doctor verifies you do not have an astigmatism but recommends a slight Cyl correction (e.g. -0.25), that is perfectly normal and is becoming more frequent when experts realize the correction can help with other day to day issues!     *For this reason it is common to see a Cyl correction written for glasses and not for contacts!
  •  Most contact brands do not make very low powered Cyl contacts and colored contact brands do not cater to astigmatism/ toric users yet!
  • You Must have a Cyl to have an Axis and a Cyl does not work with out its Axis! You need both to make the prescription work.

4. Add (ADD): If you have difficulty seeing up close due to presbyopia (common with age), your prescription may include an “ADD” value to aid near vision. This is an indicator that you need Bifocals or Progressive lens. For example:

  • ADD: +2.00

Examples of Reading a Prescription:

  1. Single Vision Prescription:

    • OD: +3.00
    • OS: +2.75
    • PD: 62
  2. Bifocal Prescription:

    • OD: -2.25 -1.00 x 180
    • OS: -2.50 -1.25 x 170
    • ADD: +2.00
    • PD: 63
Eye Prescription with eye power
    • 5. Pupillary Distance (PD): The PD is the distance between your pupils, vital for accurately aligning the lenses in your glasses. The average adult PD is around 63 mm, but it can vary. It is often written as a single number or two separate values (e.g., 31/32).
  •  There is usually 2 PD measurements written on a prescription.
  • Bigger number is your distance
  • Smaller number is your reading!
  • The whole purpose is to Pinpoint where your eyes sit on the lens
  • The closer the pupil is to the center of the lens the better!!
     -PD: 63/60    (*Higher number is your main PD)
     -63 Dived by 2 (because everyone has 2 eyes) = 31.5
     -Your PD will now be 31.5/31.5 representing per eye
* Some people are more comfortable with whole numbers
         and can round up or down by .5 to get the same PD of 63 (or
         your own prescribed PD)

6. Visit a Licensed Optometrist: Remember, always visit a licensed optometrist to get an accurate and up-to-date prescription. They will conduct comprehensive eye exams to ensure you get the perfect prescription for your unique vision needs.

Key Takeaways:

  • Sphere (SPH): Corrects nearsightedness (-) or farsightedness (+).
  • Cylinder (CYL): and Axis: Corrects astigmatism; CYL indicates power, Axis denotes orientation.
  • Add (ADD): For presbyopia, helps with near vision.
  • Pupillary Distance (PD): The distance between your pupils, necessary for accurate lens alignment.
Understanding your glasses prescription empowers you to make informed choices about your eyewear. Armed with this knowledge, you can confidently explore a wide range of frames and lens options to suit your unique style and vision requirements.
Remember, every eye is unique, so share this knowledge with friends and family, and let’s help the world see a bit more clearly!