How to Read Your Glasses Prescription

An eyeglass prescription can look like a compact table of abbreviations, plus and minus signs, and decimal numbers. Each field has a specific job. Understanding the layout makes it easier to enter the information accurately when ordering glasses online.

This guide explains the most common fields. It does not interpret whether a prescription is right for you; that is a clinical decision for your eye care professional.

First: confirm that it is an eyeglass prescription

Eyeglass prescriptions and contact lens prescriptions are different. A contact lens prescription may include a base curve, diameter, lens brand, or other fitting information. Those values should not be entered as an eyeglass prescription.

Use an up-to-date prescription written specifically for eyeglasses.

OD and OS: right eye and left eye

OD stands for the right eye, and OS stands for the left eye. Some prescriptions use plain-language labels such as “Right” and “Left” instead.

Always enter the values from each row into the matching eye. Even when the numbers look similar, do not assume they are interchangeable.

SPH: sphere power

SPH, short for sphere, is the main corrective power of the lens. It is usually written in increments such as 0.25.

• A minus sign generally appears with a prescription for nearsightedness.
• A plus sign generally appears with a prescription for farsightedness or certain near-vision needs.

The sign is part of the prescription. For example, +2.00 and -2.00 are not variations of the same value.

CYL and AXIS: astigmatism correction

CYL, or cylinder, describes the amount of astigmatism correction. AXIS describes the orientation of that correction and is expressed as a number from 1 to 180.

CYL and AXIS work together. If your prescription includes a CYL value, it will normally include an AXIS value for the same eye. If the CYL field is blank or marked “DS” or “SPH,” an axis may not be required.

Different prescribers can write cylinder values in plus-cylinder or minus-cylinder format. Enter the prescription exactly as written rather than converting it yourself.

ADD: additional near power

ADD is additional magnifying power used for near vision. It commonly appears on prescriptions for progressive, bifocal, or other multifocal lenses.

At JoyeGlasses, an ADD value is required when configuring progressive lenses. If you believe you need progressive lenses but no ADD appears on your prescription, contact your eye care professional before ordering.

PD: pupillary distance

PD is the distance between the centers of your pupils, measured in millimeters. It helps position the optical centers of your lenses.

PD may be written in one of two formats:

• Single PD: one total measurement between the centers of both pupils, such as 63 mm.
• Dual PD: separate measurements from the center of the nose to each pupil, such as 31.5/31.5 mm.

PD is not always printed on the same document as the prescription. If it is missing, ask whether your eye care provider has the measurement available.

Prism and base

Some prescriptions include prism and base values. These are specialized fields used to address certain binocular vision needs. Do not omit or estimate them.

If your prescription includes prism, base values, or any field that the online form does not clearly support, contact us before ordering so we can confirm whether the prescription can be processed online.

Example prescription layout

A prescription may be arranged like this:

This example shows the structure only. It is not a recommendation or a prescription to use.

Five checks before submitting your prescription

1. Confirm that OD and OS are not reversed.
2. Check every plus and minus sign.
3. Enter CYL and AXIS as a pair when both are prescribed.
4. Include ADD when ordering progressive lenses.
5. Confirm whether your PD is a single or dual measurement.

Never change a prescription to make it fit an online form. If the available fields do not match the document, pause and ask for help.

View the Prescription Guide

Frequently asked questions

What does “PL” or “Plano” mean?

Plano generally indicates zero corrective power in that field. Enter it only as supported by the form and as written on the prescription.

What if my prescription has no CYL or AXIS?

Not every prescription includes astigmatism correction. Leave fields blank only when that matches the prescription and the ordering form allows it.

Can I transpose a plus-cylinder prescription myself?

Do not convert or transpose prescription values unless a qualified professional has provided the converted prescription. Enter the document exactly as written.

Is PD the same as SPH?

No. SPH is lens power. PD is a physical measurement used to position the lenses in the frame.

This article is general educational information and is not a substitute for an eye examination or advice from a qualified eye care professional.

An eyeglass prescription can look like a compact table of abbreviations, plus and minus signs, and decimal numbers. Each field has a specific job. Understanding the layout makes it easier to enter the information accurately when ordering glasses online.

This guide explains the most common fields. It does not interpret whether a prescription is right for you; that is a clinical decision for your eye care professional.

First: confirm that it is an eyeglass prescription

Eyeglass prescriptions and contact lens prescriptions are different. A contact lens prescription may include a base curve, diameter, lens brand, or other fitting information. Those values should not be entered as an eyeglass prescription.

Use an up-to-date prescription written specifically for eyeglasses.

OD and OS: right eye and left eye

OD stands for the right eye, and OS stands for the left eye. Some prescriptions use plain-language labels such as “Right” and “Left” instead.

Always enter the values from each row into the matching eye. Even when the numbers look similar, do not assume they are interchangeable.

SPH: sphere power

SPH, short for sphere, is the main corrective power of the lens. It is usually written in increments such as 0.25.

• A minus sign generally appears with a prescription for nearsightedness.
• A plus sign generally appears with a prescription for farsightedness or certain near-vision needs.

The sign is part of the prescription. For example, +2.00 and -2.00 are not variations of the same value.

CYL and AXIS: astigmatism correction

CYL, or cylinder, describes the amount of astigmatism correction. AXIS describes the orientation of that correction and is expressed as a number from 1 to 180.

CYL and AXIS work together. If your prescription includes a CYL value, it will normally include an AXIS value for the same eye. If the CYL field is blank or marked “DS” or “SPH,” an axis may not be required.

Different prescribers can write cylinder values in plus-cylinder or minus-cylinder format. Enter the prescription exactly as written rather than converting it yourself.

ADD: additional near power

ADD is additional magnifying power used for near vision. It commonly appears on prescriptions for progressive, bifocal, or other multifocal lenses.

At JoyeGlasses, an ADD value is required when configuring progressive lenses. If you believe you need progressive lenses but no ADD appears on your prescription, contact your eye care professional before ordering.

PD: pupillary distance

PD is the distance between the centers of your pupils, measured in millimeters. It helps position the optical centers of your lenses.

PD may be written in one of two formats:

• Single PD: one total measurement between the centers of both pupils, such as 63 mm.
• Dual PD: separate measurements from the center of the nose to each pupil, such as 31.5/31.5 mm.

PD is not always printed on the same document as the prescription. If it is missing, ask whether your eye care provider has the measurement available.

Prism and base

Some prescriptions include prism and base values. These are specialized fields used to address certain binocular vision needs. Do not omit or estimate them.

If your prescription includes prism, base values, or any field that the online form does not clearly support, contact us before ordering so we can confirm whether the prescription can be processed online.

Example prescription layout

A prescription may be arranged like this:

This example shows the structure only. It is not a recommendation or a prescription to use.

Five checks before submitting your prescription

1. Confirm that OD and OS are not reversed.
2. Check every plus and minus sign.
3. Enter CYL and AXIS as a pair when both are prescribed.
4. Include ADD when ordering progressive lenses.
5. Confirm whether your PD is a single or dual measurement.

Never change a prescription to make it fit an online form. If the available fields do not match the document, pause and ask for help.

View the Prescription Guide

Frequently asked questions

What does “PL” or “Plano” mean?

Plano generally indicates zero corrective power in that field. Enter it only as supported by the form and as written on the prescription.

What if my prescription has no CYL or AXIS?

Not every prescription includes astigmatism correction. Leave fields blank only when that matches the prescription and the ordering form allows it.

Can I transpose a plus-cylinder prescription myself?

Do not convert or transpose prescription values unless a qualified professional has provided the converted prescription. Enter the document exactly as written.

Is PD the same as SPH?

No. SPH is lens power. PD is a physical measurement used to position the lenses in the frame.

This article is general educational information and is not a substitute for an eye examination or advice from a qualified eye care professional.