Eyewear Guidance

How to Read Your Eyeglass Prescription

Those rows of abbreviations and numbers are simpler than they look. A plain-language guide to what your prescription is actually saying about your eyes.

Published August 19, 2026/5 minute read

A Prescription Is a Map, Not a Mystery

After an eye exam, most people leave with a small card full of abbreviations and numbers, nod politely, and never look at it again. But that card is a precise description of how each of your eyes focuses light, and understanding it helps you make better decisions about lenses, frames, and when it is time for an update.

Every eyeglass prescription describes, for each eye, the lens power needed to bring your vision into clear focus. The layout varies slightly between providers, but the vocabulary is universal.

The Abbreviations, Translated

Here is what the standard terms on a prescription mean:

• OD and OS: oculus dexter (right eye) and oculus sinister (left eye). Some prescriptions use RE and LE instead.
• SPH (sphere): the main lens power. A minus number corrects nearsightedness; a plus number corrects farsightedness.
• CYL (cylinder) and Axis: present when you have astigmatism, describing how much correction is needed and at what angle.
• ADD: the extra magnifying power added for reading in bifocal or progressive lenses, common after age 40.
• PD (pupillary distance): the millimeters between your pupils, used to center the lenses correctly in your frames.
• Prism: a less common value that corrects eye alignment issues such as double vision.

What the Numbers Say About Your Vision

Lens power is measured in diopters, and the further the number is from zero, the stronger the correction. A prescription of -1.00 describes mild nearsightedness, while -6.00 is a strong correction that benefits from thinner, high-index lens materials. For astigmatism, the CYL value matters as much as the SPH: even a moderate amount can cause headaches and blur if the lens is not aligned to the Axis value during fabrication.

This is also where PD becomes critical. An accurate PD places the optical center of each lens directly in front of your pupil. A PD that is off by even a few millimeters can produce eye strain that feels like a wrong prescription, which is one reason we measure it carefully for every pair made through the boutique.

How Long a Prescription Stays Valid

In Florida, eyeglass prescriptions are generally valid for a period set by your prescriber, often one to two years. Vision changes gradually, so a prescription can feel fine long after your eyes have shifted. If you are squinting at your phone, getting end-of-day headaches, or holding menus at arm’s length, it may be time for a new exam rather than a new frame. Our services page explains how we work with outside prescriptions.

Bring your prescription card to your next visit and we will walk through it together. Understanding your numbers makes choosing lenses, from everyday single vision to progressives, a far more confident experience.

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