How To Read Your Eye Prescription
Overview
Reading your eye prescription is easier than it looks once you understand a few key abbreviations. Each value indicates a specific vision requirement and ensures your lenses are made with the precision needed for comfortable, accurate sight.
Understanding your glasses prescription
Your prescription may be digital or printed. It includes measurements for each eye that outline whether you’re nearsighted, farsighted, have astigmatism or need reading support.
Eye prescription chart abbreviations
OD / R: right eye
OS / L: left eye
PD (Pupillary Distance): the distance between your pupils, used to centre your lenses
SPH (Sphere): how much correction you need for nearsightedness (-) or farsightedness (+)
CYL (Cylinder): lens power needed to correct astigmatism
Axis: angle of astigmatism correction
Other eye prescription abbreviations
- Prism: used to correct double vision.
- ADD: extra lens power for reading, found in bifocals or progressives.
Notes: The type of Rx glasses you need for vision correction may be noted on a glasses prescription, such as DV (Distance Vision/nearsightedness) and NV (Near Vision/reading).
Nearsighted prescription
If you’re nearsighted (myopia), meaning you see close-up objects clearly but struggle with distance vision, your SPH number will have a minus sign (–). This indicates you need help seeing things far away.
Farsighted prescription
If you’re farsighted (hyperopia), meaning you see distant objects clearly but have trouble focusing on things up close, your SPH number will have a plus sign (+). This shows you need help with near vision tasks.
Astigmatism prescription
Astigmatism, which causes blurry or distorted vision at all distances due to an irregularly shaped cornea or lens, is corrected with CYL and Axis values. If these sections are blank, your prescription likely doesn’t include astigmatism correction.
How strong is my eye prescription?
There’s no such thing as a “good” or “bad” prescription. Some are simply stronger than others. Higher numbers (like -5.00 or +5.25) indicate stronger correction needs.
EXPERT'S TIP!
“If you squint, feel eye strain or get headaches, even with mild numbers, properly fitted lenses can make a big difference in comfort and clarity.”
Maria Horan, Certified Optician
How often does your eye prescription change?
Changes take place within two years, and sometimes even within a year, due to lens opacity, health changes or new medication.
How long is your eyeglass prescription good for?
Prescriptions are typically valid for two years, depending on local regulations. The issue and expiration dates will be listed on your prescription.
Understanding your vision correction needs
Once you know what each abbreviation means, reading your prescription becomes simple.
These details guide lens specialists in creating accurate, comfortable eyeglasses tailored to your needs and make ordering glasses online more straightforward. You’ll also feel more confident choosing the right lenses and options for your lifestyle.
Still unsure? reach out to our optical experts for any doubts.