Eyeglass Prescription Terms With Abbreviations

What Are Prescription Glasses?

Prescription glasses are best compared to medicines intended to target a specific illness. For example, if you are suffering from inflammation, you are prescribed non-steroidal anti-inflammatory drugs to help reduce the inflammation.

The concept is almost similar to the prescription glasses-the lens of this eyewear is specifically intended to correct your vision problems. These glasses are designed to make your vision clearer and more accurate.

The eyeglass prescription is usually from an optometrist, containing the specific values required for the right and left eye. The values indicated in the prescription will be based on the refraction conducted during the eye examination.

How Do Prescription Glasses Work?

Prescription eyeglasses work by either adding or subtracting the focus power to your cornea and lens. These glasses allow your eyes to focus light on the right spot of your cornea. If, without glasses, everything is almost blurry, with prescription glasses with the correct power, you should be able to make out the images clearer.

The lenses on your glasses will bend the light as it enters or passes through your eye, allowing your retina to focus better and providing clearer visuals.

These prescription glasses usually have a timeline of one to two years; after that, you need to get refracted again to make the necessary adjustments to your glasses lenses.

Eyeglass Prescription Terms With Abbreviations

When doctors give your eyeglasses with a prescription, you will automatically notice some terms and abbreviations that don't make sense. Even without any eye problems, you need to do a double take and figure out what those details in your prescription mean.

So, here's a list of the most common prescription glasses terms with corresponding abbreviations to give you an idea of what your optometrist and ophthalmologist mean.

1. OD And OS

OD stands for the right eye, and OS for the left eye. Derived from Latin terms, OD stands for oculus dexter, which in Latin means right eye, while OS is the abbreviation for oculus sinister or left eye. Both eyes are sometimes referred to as oculus uterque or OU.

Most doctors use OD, OS, and OU, but some opt for RE for the right eye, LE for the left eye, and both for both eyes.

2. Sphere Or SPH

This is indicative of whether you are nearsighted, farsighted, or both. Usually, a positive or a negative sign follows this, then a number pointing to the lens power you need to correct your vision.

If the number that comes with SPH has a negative sign before it, it means that you have nearsightedness, while a positive sign indicates farsightedness. 

Some prescriptions based on your eye examinations may have negative and positive symbols, which means that you are suffering from both nearsightedness and far-sightedness and need vision correction specific to each eye and condition.

3. Plano Or PI

When your prescription has the word "Plano," an abbreviation of "PI," or even the infinity symbol, it means you are not suffering from any distance problems. Nearsightedness or farsightedness has been ruled out, but this doesn't guarantee that you don't have astigmatism.

4. Pupillary Distance or PD

This measures the distance between the pupils of your eyes and is measured in millimeters. Not all prescriptions include this abbreviation, but online tools and video tutorials are available to help you find the pupillary distance of your eyes at home. The value for PD can be anywhere between 58 mm to 68 mm, with women having an average PD of 62 mm and men having an average of 64 mm.

5. Axis

This is measured in degrees and indicates the exact location of astigmatism on your eye's cornea. If your doctor concludes that you have astigmatism, you'd see additional abbreviated terms like CYL on your prescription, and it would have a specific value or number next to it.

This number will guide your eye care doctor to determine where the cylindrical power should be set in your eyeglass lenses. Note, though, that axis is only associated with the position of your astigmatism and has no bearing on the strength or power of the lenses you need to correct your vision problem.

6. Cylinder Or CYL

If you see CYN on your prescription, you have astigmatism, and if a number comes before or after the abbreviation, your vision problem can be corrected. 

Again, the number would have a positive or negative symbol before it, which dictates the lens power you need to correct your condition. The larger the number is, the more severe your astigmatism is.

7. Addition or Add

This term is only occasionally present on eyewear prescriptions. The term "add" indicates the magnifying power added to the lower portion of your progressive or multifocal lens to correct presbyopia. 

This is an additional visual treatment for reading and is commonly applied to reading glasses. Note that this extra power will always be the same for both eyes.

8. Distance Or Dist, Intermediate Or Inter, And Near

The distance that is indicated pertains to the prescription that is required to correct your vision problem. Your eyeglasses with a prescription must suit all your activities, especially essential ones like walking and driving.

Intermediate is for those who need to have their immediate vision corrected. At the same time, near-prescription eyeglasses are intended for those diagnosed as being near-sighted and those whose job includes attention to detail and numbers.

Start a conversation with your optometrist once you have your prescription. Most of the time, these professionals will explain bits and pieces about what the numbers mean and how to resolve your visual problems. But you can always ask questions.

 It also pays to shop around, especially when purchasing your lenses' frame. You'd want it to be able to hold and keep up with your lenses by checking eyeglasses online. Or you can also get feedback from your doctor on what they think are among America's best eyeglasses, so you just need to shortlist the brands and review the feedback.