How to Read My Glasses Prescription?

How to Read My Glasses Prescription?

Have you ever gotten an eye exam and wondered, what do all these numbers mean on my prescription? We are here to help clear up any confusion and explain how you can figure out your prescription range. Once you understand what each number and abbreviation means, you’ll have a better understanding of what type of frames can hold your prescription and what vision type best suits your needs.

gunnar prescription explained


What does OD and OS mean on my prescription?

The OD and OS simply refers to your right and left eye. OD is the abbreviation for your right eye while OS is for your left eye. OD comes from the Latin phrase “oculus dexter”, which means right eye. OS comes from the Latin phrase “oculus sinister”, which means left eye.

In some instances, your doctor may abbreviate the eye column with OU. OU comes from the Latin phrase “oculus uterque”, which means both eyes.

What does Sphere (SPH) mean on my prescription?

If you need lenses to correct nearsightedness or farsightedness then a power will be listed under this section. The Sphere number indicates the lens power prescribed to correct one of those two vision needs. If the number under Sphere has a (+) sign then you are farsighted. Vice versa if the number under Sphere has a (-) sign then you are nearsighted.

What does Cylinder (CYL) mean on my prescription?

Cylinder tells you the amount of power needed in the lens to correct the astigmatism in either your right or left eye. Like the Sphere, if your Cylinder has a (+) sign then you need correction for nearsighted astigmatism. If you have a (-) sign then you need a correction for farsighted astigmatism.

Sometimes you will see the doctor leave this section blank indicating your astigmatism is not too strong and doesn’t need to be corrected.

What does the Axis mean on my prescription?

If your prescription has a Cylinder power listed then it will always have an axis value. Essentially, the axis describes the lens meridian needed to correct your astigmatism. The axis will contain a number between 1 to 180. This number indicates in which direction the Cylinder power must be placed on your lenses. 90 indicates the vertical position while 180 is the horizontal position.

What does Add mean on my prescription?

The Add you will see on your prescription stands for the “added magnifying power”. This is only applied to the bottom of the lens for progressive or multifocal lenses to correct presbyopia. Presbyopia is the natural farsightedness that comes when your eyes get older. The add power will always be a (+) power and it will range from +0.75 to +3.00.

What does Prism mean on my prescription?

The Prism correction you might see on your prescription is to help correct diplopia, also known as double vision. This is when someone looks at an image and sees two of it. The Prism helps align those two images and ensure you only one.

Only a small amount of people needs a Prism correction on their prescription lenses. Prism will be listed in two different ways. Either as a metric (0.5) or a fraction (1/2). Then the direction of the Prism on the lens will be on the thickest edge. The four abbreviations you may see are BD (Base down), BU (Base up), BO (Base out), or BI (Base in).

  Sphere Cyl Axis Add Prism Base
OD -1.25 -1.50 68 +2.00 0.5 down
OS -2.75 -1.25 170 +2.00 0.5 up

What is the Rx range for my prescription?

how to read glasses prescription


When reading your prescription it's important to understand what the total power is. Many prescription dealers, including GUNNAR, will list the prescription range for each individual frame. For example, the popular GUNNAR Intercept has a prescription range of -6 to +5. Let’s see if the example prescription above would work for the Intercept.

When reading a prescription, you combine the Sphere and CYL to get your total power for each eye. So, in the example above the Right Eye: (-1.25) plus (-1.50) equaling a -2.75 Total Power. The Left Eye: (-2.75) plus (-1.25) equaling a -4.00 Total Power. This prescription would work with the Intercept since it does not exceed the -6 range.

How long does it take to adjust to new glasses?

Now that you better understand what your prescription means, the next step is actually getting your new glasses. You can likely purchase glasses at the same place where you had your eye exam or you can order glasses online.
Once you receive your glasses, it’s usually smooth sailing. It generally only takes a few days to adjust to a new pair of prescription glasses, although some people take up to two weeks to fully adjust.

What might you experience when getting used to new glasses?

While some people don’t notice anything except better vision when adjusting to a new prescription, many people will go through an adjustment period. During this time, you may experience some (or all) of the following symptoms:

  • Dizziness
  • Nausea
  • Blurred vision
  • Visual distortions
  • Issues with depth perception
  • Headaches
  • Eyestrain

While these symptoms might be a bit alarming at first, don’t worry! Temporary, mild symptoms are normal and suggest that your eyes and brain are learning to process images differently. This is a good thing and means your vision is in the process of correcting itself. This process can put a bit of strain on your eyes and lead to the above symptoms, but they won’t last long.

It can also take some time to get used to the frames themselves, especially if these are your first pair of glasses. The feeling of having something new on your face can be weird and a bit uncomfortable. Rest assured that any odd or awkward feelings will go away within a couple of weeks as you grow accustomed to your new facial accessory. Soon enough, you won’t even notice they’re there!

How to get used to new glasses

The biggest factor in getting used to your new glasses is simply time, however, there are some things you can do to make the process more pleasant:

  • Keep your glasses clean: Dirty lenses can make your vision blurry, adding to any blurriness you may already be experiencing. Most new glasses come with a cleaning cloth, so make sure to use it!
  • Practice the 20-20-20 rule: If you spend a lot of time looking at screens, practice the 20-20-20 rule to give your eyes a rest. This rule suggests that for every 20 minutes spent looking at a screen, you should look at something 20 feet away for 20 seconds.
  • Wear blue light blocking glasses when using screens: To prevent further eye strain, wear blue light blocking glasses when using digital screens. GUNNAR’s blue light glasses are available with or without prescriptions, so you can wear your prescription GUNNAR blue light blocking glasses when using digital devices and your regular glasses when out and about.

Are there things you should avoid while getting used to your glasses?

When you’re getting used to your new glasses, there are few things you should avoid. Because your balance and vision might be a bit off, we don’t recommend driving long distances, operating machinery, or engaging in strenuous activities for the first few days after getting a new prescription. Instead, take advantage of this time to relax as you give your eyes time to adjust to the new prescription. Stick to low-key activities that don’t require visual acuity and good balance.

Are new glasses supposed to be blurry?

While a new prescription can make your vision a bit blurry as your eyes are adjusting, your vision should not stay blurry for more than a few days, or two weeks at the most. You may have a longer adjustment period if you’re using glasses for the first time or if there’s a big prescription change. If you’re experiencing headaches, blurred vision, eye strain, or any of the other above-mentioned symptoms after two weeks of regularly wearing your new glasses, it’s time to contact your eye doctor. Your doctor will discuss your concerns, examine you, and determine what is causing your persistent symptoms.

The bottom line

Adjusting to new glasses can be an annoying and sometimes uncomfortable process, but take heart: it won’t last forever. Your eyes and brain are working hard to allow you to see clearly, so just take it easy and give it some time. Soon enough, you’ll be rocking your new lenses with confidence and clarity!

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