How to Read Prescription

【How to Read and Enter Your Eyeglass Prescription】

It is quite easy to place an order at FitGlasses.com even you don’t understand how to read your eyeglass prescription. We have provided assistance with how to read and enter your prescription in the following information. If it still does not work for you, you can email us your eyeglass prescription to Info@fitglasses.com together with your name or member ID, or provide your doctor’s information so that we can contact your doctor directly and get your correct prescription.

Below are examples of what a prescription looks like and how it would be entered into our website.

Sample A: Single Vision

Single Vision prescriptions are for patients who have trouble seeing either near or far (but not both). Check the example below. As you can see, the prescription has no value in the ADD column.

The numbers are diopters, the units of focusing power needed to correct vision. The higher the diopter number, the more vision correction the patient needs. A plus sign indicates farsightedness, while a minus sign indicates nearsightedness.

Sample B: Bifocal /Progressive (Assume PD=62MM for distance)

As you can see, the prescription has a value in the ADD column. You will only have an ADD measurement if you wear bifocal/progressives lenses.

Sample C: Single Vision with Prism

【How do I know if my prescription is single vision, bifocal, or progressive?】

First of all, you need to get your eyes properly examined by

your optometrist or ophthalmologist to know about the lenses that you may require to correct your vision. Then you will be able to confirm which kind of lens your are opt for. Your prescription would also help you decide whether you need glasses for long/near distance or for reading. 

Related Eyeglass Prescription Abbreviations

OD - Oculus dexter which refers to the right eye.

OS - Oculus sinister which refers to the left eye.

OU - Oculus uterque which refers to both eyes. If you see this, please enter the same prescription for both eyes.

Sphere or Power - SPH or PWR - this is written in 0.25 increments. If the field has 'SPH', 'PL', 'PLANO', or '00', your should enter 00 as prescribed.

Plano - PL - This indicates there is no spherical correction in this eye. A plano lens would have no focusing power or correction to it.

Pupilary Distance - PD - This is the distance between your right pupil and left pupil. A more detailed explanation of Pupillary Distance can be found in our How to measure PD by yourself? page.

Balance - This indicates there is no vision correction in this eye. It's a non-prescription lens and is used when only one of your eyes requires vision correction

Cylinder - CYL - This indicates the amount of astigmatism, and is written in 0.25 increments. Not all prescriptions have a cylinder correction, and some prescriptions have a cylinder correction in only one eye. If you don't have an astigmatism correction then your doctor may leave this field blank, or they may put 'SPH', 'DS', 'Plano', or '00' in this field. This means you do not have an astigmatism correction in one or both eyes.

 Axis - AX or X - This is also part of the astigmatism correction, and is written in increments of 1 (one). If there is no cylinder, then there should be no axis. Since it's a degree/angle, it will be represented as a value between 1 and 180. If there is no cylinder, it's possible that the doctor might enter 0, but this would just indicate that there is no axis.

 ADD - This is a value that is commonly used for bifocal or progressive lenses, as well as reading glasses. It indicates how much power gets added to the distance Rx to create the reading-only Rx;

Prism or Base or Base Curve - A prism is used when both eyes are not properly aligned and they need a prism to re-align them. The Base is the rotation of the prism. There are two separate parts to a Prism correction. The first part is the diopter strength (e.g. 1.0) and the second is the direction (e.g. BI). There are four different directions. Base-Up (BU), Base-Down (BD), Base-In (BI), and Base-Out (BO).

Segment Height or Seg Height - SH - This is the vertical measurement from the bottom of the lens to[6]  the beginning of the progressive addition on a progressive lens, or the top line of a lined bifocal. Segment height does not apply to Single Vision lenses. You will need the frame in order to measure segment height because you can only measure it while the glasses are on your head.

Near Vision or Near Vision Only - NV or NVO - This is written when your doctor is recommending reading-only glasses. (This is also known as farsighted)

Distance Vision or Distance Vision Only - DV or DVO - This is written when your doctor is recommending distance-only glasses. (This is also known as nearsighted)

Astigmatism - An optical condition that can cause blurry vision. This is corrected by a Cylinder and Axis correction on a prescription.

Binocular - A term used to describe the simultaneous use of both eyes at the same time.

Monocular - Refers to only one eye.

Progressive Additive Lens - PAL - The ADD value specifically for progressive lenses.