Learn About Your Prescription: What Does It Actually Mean

How to understand and read your prescription for eyeglasses

You're not the only one who has ever looked at your prescription and thought it had more confusing acronyms that a text conversation between two teens. We are here to help you understand your prescription.

 

One-time or ongoing prescriptions

Prescriptions generally fall into one of two categories: progressive or single. Let's take a look at each.

 

Single Vision Prescription

One-vision prescriptions correct for only one field of vision, either near or immediate. This lens type corrects nearsightedness and farsightedness.

 

Progressive Vision Prescription

Progressive-vision prescriptions correct multiple fields of vision, usually near, intermediate, and close/reading. Progressive lenses can be multi-focal and have three viewing areas, with no visible lines connecting them.

 

Prescriptions for Prism

A prism prescription is possible if you have problems with vision alignment, difficulty focusing, poor depth perception and double vision.

 

Your prescription for eyeglass lenses

These are the basics

 

OD, OS = Right eye, left eye

You can read more about it here

OD = Oculus Devixter (the right side of the eye).

OS = Oculus Sinister (the left side of the eye).

OU = Oculus Uterque (both eyes)

 

PD = Pupillary Distance

Pupillary distance (PD) is the distance between your pupils. Prescription glasses have a pupillary distance (PD). This is the area where prescription glasses are placed.

 

SPH, AXIS, CYL = Sphere, Cylinder, and Axis.

Three measurements make up an eye prescription: the sphere, cylinder and axis. These numbers will also help you determine the type of vision correction that you require.

 

SPH = Sphere

The number in the sphere indicates whether you are nearsighted or farsighted. This measurement is done in a unit called a diopter, or "D". If you're nearsighted, the measurement will be a negative with a (-) symbol. This measurement will be a negative number with a symbol ( - ). If you are farsighted, it will usually be a positive number with an (+ ) symbol. The correction will be stronger if the number is higher than the original.

 

CYL = Cylinder & Axis

A cylindrical curve lens is required for astigmatism, which is a condition that causes a slightly oval-shaped cornea. This prescription comes with a cylinder and an "axis number" (1deg-180deg), that tells the lens maker where the correction should be placed in the lens. Take this example:

 

Segment Height

This measurement allows you to precisely place your progressive power lenses. This is the distance between the bottom of your lens and the center of the pupil while wearing the glasses. This value is required for all progressive orders.

 

Add Value

This measurement allows you to precisely place your progressive power lenses. This is the distance between the bottom of your lens and the center of the pupil while wearing the glasses. This value is required for all progressive orders.

Now that you are able to read your prescription accurately, you can easily update your glasses from anywhere in the world.