How to read your prescription.
SPH, CYL, AXIS, ADD – what the numbers mean, and how to enter them when you choose your lenses.
What they mean
SPH · Sphere
The main lens power. Minus (–) means short-sighted, plus (+) long-sighted.
CYL · Cylinder
Corrects astigmatism. Empty box? Then you have no astigmatism – choose 0.00.
AXIS
From 1 to 180. It belongs to the cylinder and is only needed when CYL has a value.
ADD · Addition
Extra reading power for progressive and bifocal lenses.
OD is right, OS is left
OD (oculus dexter) is your right eye, OS (oculus sinister) your left – some prescriptions just write R and L. Your PD, the distance between your pupils, is often on the prescription too. If not, measure it at home.
Don’t want to type it?
When you choose your lenses, upload a photo or PDF of your prescription instead – or send it after you order. Our opticians check every value before your lenses are made.
Reading a prescription
Knowing how to read an eyeglass prescription is essential! While you likely know whether you’re nearsighted, farsighted or have astigmatism, determining that from your prescription slip is another thing entirely. That’s why we’ve put together a short guide to help you learn how to read a glasses prescription so you can get to ordering your new set of eyeglasses as quickly as possible.
If you complete an eye exam and find your eyes’ needs have changed, you need to order a new prescription as soon as possible. That’s where your new prescription from your optometrist or ophthalmologist comes in.
Most online retailers ask you to read and input your prescription into their order form, but if you don’t know how to read your prescription, that process can get complicated.
What do all these letters and numbers mean?
The numbers on your eyeglass prescription describe precisely how your glasses lenses should be cut. Keep your prescription up to date so these numbers can accurately reflect your visual needs. Typically, you’ll see several abbreviations and words labeling all of the important data on your prescription. See below to learn the meaning of SPH, CYL Axis, Prism, PD, and more.
OD vs. OS Eye
OD is short for the Latin term oculus dexter which means right eye.
OS is an abbreviation of the Latin oculus sinister which means left eye. You’ll often see this terms on eyeglass prescriptions.
Sphere, Cylinder, and Axis on Eye Prescriptions
Sphere: The sphere (SPH) on your prescription indicates the lens power you need to see clearly. A minus (-) symbol next to this number means you’re nearsighted, and a plus (+) symbol means the prescription is meant to correct farsightedness.
Cylinder: The cylinder (CYL) number indicates the lens power needed to correct astigmatism. If this column is blank, it means you don’t have an astigmatism.
Axis: An axis number will also be included if you have an astigmatism. This number shows the angle of the lens that shouldn’t feature a cylinder power to correct your astigmatism.
Talk to us.
Write to service@igioo.com – we answer within 24 hours on weekdays and 48 hours at weekends.
