Figuring out a doctor’s note with notoriously cryptic handwriting is no simple task. Asking from people to understand a prescription for glasses (especially multifocal prescriptions) can be even trickier.
As the ancient joke goes –
A man goes to see his doctor.
“Someone decided to graffiti my house last night!” he said in rage.
“So why are you telling me?” the doctor asked.
“I can’t understand the writing,” I replied. “Was it you?”
But struggling to read your glasses prescription isn’t a joking matter, especially if you’re not buying your glasses straight from your doctor/optometrist (who charge too much for glasses). Online options provide the same quality of prescription eyeglasses, at much better prices. But you usually need to fill out the eye prescription on your own. Some people find it intimidating.
It shouldn’t be. In this article, we’ll go over the different values in an eye prescription, so next time you won’t have any problems figuring out what each number represents, and how multifocal prescriptions differ from single vision ones.
(This is an online prescription fill-in segment from GlassesUSA.com)
(Generic Rx. note for eyeglasses)
OD & OS: Sometimes appear as O.D. and O.S. (oculus dexter and oculus sinister). In the prescription, the information on your right eye (OD) will always appear before the info on your left eye (OS).
OU appears in some prescriptions. It means both eyes. Some doctors avoid latin and use RE and LE for each eye.
SPH: Sphere, the power of your prescription. Can appear as PWR as well. If the numbers in this column have a minus (-), this means you are nearsighted (myopia). If it’s a plus (+), you are farsighted (hyperopia). The value is measured in diopters.
CYL: Cylinder. The amount of lens power for astigmatism. A minus before the number in this column is for nearsightedness, a plus for farsightedness. If you have no or very slight astigmatism, nothing will appear in this column. The value is measured in diopters.
Axis.: Or shows up as Ax. Like CYL, it applies to astigmatism, so if there’s not CYL, there will be no number under AX. It’s measured in degrees/angles, and the number will be between 1 and 180.
Add: Only used for multifocals. Added magnifying power to correct presbyopia, which means adding power to the distance Rx in order to create reading-only Rx. Usually, it will range between +0.75 to +3.00. Some prescriptions from a doctor will mention PAL, which means you’ll need a different addition to progressive adjusted lens compared to bifocal multifocal lenses.
Prism: Prismatic power added to compensate for eye alignment problems. A small percentage of prescription glasses include a prism.
PD (pupillary distance) is also an important part of the prescription, referring to the distance between the center of your pupils.
Two final (and important) reminders
1. An eyeglasses prescription is not a prescription for contact lenses. Contacts prescriptions are obtained in a contact-lens specific fitting, and they include additional information (base curve, lens diameter and more) and the prescription power is often different because glasses have a small distance from the eye, while contacts sit right on the eye.
2. Something some people don’t know is that the prescription is yours to keep. What does it mean? A doctor cannot condition giving you your prescription on you agreeing to purchase glasses from them. A copy of any prescription that includes a refraction, whether multifocal prescriptions or single-vision, must be given to the patient after the exam, without charging extra.