How to read your eyeglass prescription

Eyeglass prescriptions can be written in various ways but generally, they are either printed or handwritten on a table.

Like most people, looking at these values can seem like reading a foreign language but its actually quite easy to follow once you understand the key terms.

This guide will outline all the key terms in your prescription, what the numbers really mean in terms of your vision correction and how to enter them when you order glasses online.

Prescription Terms

O.D./RE/R

Indicates the right eye’s prescription. O.D. is Latin for oculus dexter. RE stands for “right eye” and R stands for “right”.

OS/LE/L

Indicates the left eye’s prescription. O.D. is Latin for oculus sinister. LE stands for “left eye” and L stands for “left”.

Sphere

Specifies the lens power prescribed to correct your vision correction. It’s expressed as either a (+) for farsightedness/hyperopia or (-) for nearsightedness/myopia value.

Cylinder & Axis

Indicates an astigmatism correction for the eye. The “Cylinder” will indicate the strength of correction needed and the Axis will determine the angle of correction. Both values are required to make your prescription lenses.

ADD/Addition

Applies for reading, intermediate, anti-fatigue, bifocal and progressive prescriptions. It specifies the magnifying power needed to correct issues for near vision.

Pupillary Distance (PD)

The exact measurement, in millimetres (mm), between the center of your pupils. The PD measurement acts as a guide to make sure the lenses have been centred according to the position of your pupils.

Prism

Indicates eye alignment issues. The values specify the amount and direction needed for correction. Prescriptions with prism will also include additional terms like:

  • BO - Base Out
  • BU - Base Up
  • BI - Base In
  • BD - Base Down

What do the numbers on my prescription mean?

The values in your prescription can identify the type of vision correction you need. The numbers will determine how your prescription lens will be cut, depending on the strength and type of corrective power.

Myopia/Nearsightedness

Myopic or nearsighted prescriptions can be identified with a minus (-) symbol in the “sphere” section of your prescription.

These prescriptions mean that you are able to see things clearly up close but have trouble seeing things from far away, hence the name nearsighted.

Hyperopia/Farsightedness

Hyperopic or farsighted prescriptions can be identified with a plus (+) symbol in the “sphere” section of your prescription.

These prescriptions mean that you are able to see things clearly at a distance but have trouble seeing things up close, hence the name farsighted.

Astigmatism

Astigmatic corrections are identified anytime there are values present in the “cylinder” section of your prescription. There should also be a value present in the “axis” section of your prescription that is related to the astigmatism correction.

Simply put, astigmatism is a problem associated with how your eyes focus light.

If you are diagnosed with astigmatism, it means that your eye is unable to equally focus light on the retina leading to blurred or distorted vision.

Presbyopia

Presbyopia is an age-related condition where your vision becomes blurry when you’re trying to see things up close. It’s a gradual process and occurs naturally as you age. You may start to notice symptoms of presbyopia around the age of 40 and above.

Prism

Prescriptions with prism indicate that there are alignment issues with your eyes. The values listed on the prescription specify the amount and direction needed to correct these alignment issues.

How do I enter my prescription for glasses online?

Now that you have an understanding of what the key terms mean in your eye prescription, you should have no problems with entering these values online.

If you’re looking at your prescription and see that some of the cells in the table may not be populated or aren’t even listed, that’s okay.

Depending on your prescription, some of these terms may not apply. Simply input the numbers in the correct sections and disregard areas that are not applicable to your prescription.

Special notes and additional information

In some cases, you may find a section for notes or additional information listed on your prescription. These notes are often suggestions to specific lens designs, lens coatings or comments listed from your optometrist.

Lens Designs

The lens design can be broad or specific depending on your optometrist. It can be as simple as the type of corrective lens you will need like a single vision, bifocal or progressive lens.

Some optometrists may also include the lens index that best suits your prescription from a low-index, a mid-index, to a high index lens.

Occasionally your optometrist may recommend a specific brand depending on their knowledge and experience on that specific lens.

Lens Coatings

Lens coatings are special treatments to the lens that enhance the aesthetic and visual acuity of your prescription lenses. Here’s a list of some of the lens coating suggestions you may see:

  • Anti-reflective coating - eliminates glare that’s reflected on the lens. It allows more light to pass through and makes your lenses look much better.
  • UV Protection - filters harmful UV rays that are emitted by the sun.
  • Photochromic/Transitions - light adaptive lenses that are clear indoors and darken when exposed to UV light, or when you’re outside.
  • Blue Light Blocking/Filtering - protects your eyes from blue light emitted by LED screens (phones, tablets, computers and other mobile devices) and artificial light sources.