What Does My Eyeglass Prescription Mean?

An eyeglass prescription can look like a grid of unfamiliar numbers and abbreviations. Here’s a simple guide to the most common terms so you can better understand what’s written on your prescription.

OD and OS

These abbreviations identify each eye:

• OD means the right eye.
• OS means the left eye.
• OU, if listed, means both eyes.

SPH or Sphere

Sphere describes the main lens power used to correct nearsightedness or farsightedness. A minus sign generally indicates nearsighted correction, while a plus sign generally indicates farsighted correction.

CYL or Cylinder

Cylinder is the amount of correction for astigmatism. This field may be blank if your prescription doesn’t include cylinder correction.

AXIS

Axis describes the orientation of the astigmatism correction. It’s written as a number from 1 to 180 and appears when a cylinder value is included.

ADD

Add is extra lens power for near vision, often used in bifocal or progressive lenses. It’s commonly the same for both eyes, but your prescription will show what applies to you.

PRISM

Prism may be prescribed to help the eyes work together by adjusting how light is directed through the lenses. If your prescription includes prism, it may list an amount and a base direction.

A note about your prescription

Every prescription is specific to the person it was written for, and the numbers are meant to be read together. This guide is for general information; it doesn’t replace advice from your eye-care provider. If you have questions about your prescription or whether it’s still current, contact the provider who issued it.

Bring your prescription to a Specs location and our team can help you understand the eyewear options available for it.