You just finished your annual eye exam and with prescription in hand, you're thinking about what kind of cool eyeglasses to try. Have you ever looked at all those numbers and letters and wondered what exactly do they mean? Whether you’re a longtime glasses wearer or a newbie, knowing how to decipher your prescription will give you a better understanding of what the eyeglass prescription could say about your vision and overall health.
Your eyeglass prescription is typically written in a grid like the one below, using a combination of terms, abbreviations, and numbers.
Usually you’ll see these abbreviations along the left side:
O.D. stands for oculus dexter, meaning right eye.
O.S. stands for oculus sinister, meaning left eye.
Then along the top, you may see this lingo. These abbreviations reflect the measurements of specific aspects of your vision, and can be pretty confusing at first.
SPH (or Sphere) indicates the eyeglass prescription power, or how strong your lenses need to be to correct your vision.
CYL (or Cylinder) indicates astigmatism, a condition where the cornea is irregularly shaped causing blurred or distorted vision. It also tells the lens strength needed to fix it.
AXIS describes the degree and direction of your astigmatism.
ADD is added magnifying power in the lower part of a multi-focal lens. It’s used to correct presbyopia which is the inability to focus on close objects. If you need a bifocal or progressive lens, there will be an ADD.
Your glasses prescription includes a number for every aspect of your vision that needs correction. When learning how to interpret your prescription, keep in mind that usually the further from zero the numbers are, the more correction you need.
A plus or minus sign in front of your glasses prescription number is shorthand for near or farsightedness.
+ means you’re farsighted or have trouble seeing things close up. - means you're nearsighted, or struggle with seeing far away.
IS YOUR RX (PRESCRIPTION) SINGLE VISION OR MULTI FOCAL?
Single and multi-focal eyeglass prescriptions will look different.
If your vision correction is single vision, that means your lens power corrects for nearsighted or farsighted, but not both. The ADD column (which stands for additional magnifying in a multi-focal Rx) is +2.00 in the sample Rx above. If you’ve got an eyeglass prescription for bifocal or multi-focal/progressives, your lens power corrects for near, far, and sometimes intermediate range vision. You’ll have a number in the ADD column.
No matter what your eyesight numbers are, or whatever kind of vision correction you need, it's good to have your eyes examined about once a year to make sure your prescription for eyeglasses or contact lenses is up to date.