At Berkeley Eye Center, our eye doctors write hundreds of eyeglass prescriptions each year. The information on the prescription tells the lab exactly what type of lenses you’ll need to have the best vision possible.
While the meaning of all those abbreviations, acronyms, initials and numbers are very clear to the folks in the lab, to many of our patients the prescription seems to be written in some kind of secret code.
There are many different eyeglasses prescription formats — grid, blank, vertical, etc. — they will all contain the same basic information.
Let’s take a look at your typical grid form eyeglasses prescription:
Columns on the Left of Your Eyeglasses Prescription
In the left hand column, you’ll see the initials OD and OS right beneath the Rx symbol. These are abbreviations for Latin terms that describe which eye the doctor is referring to:
- OD stands for “Oculus Dexter”, which means your right eye.
- OS stands for “Oculus Sinister”, which means your left eye.
In some instances you may see the initials OU, which stands for “Oculus Uterque”, referring to both eyes. Also, an eye doctor may substitute RE (Right Eye) for OD and LE (Left Eye) for OS.
Rows Along the Top
The top row consists of six abbreviations. Depending on your vision problem, all or some of the boxes under these headings will be filled out.
SPH (Sphere) is the lens power needed to correct your vision problem.
CYL (Cylinder) is the lens power needed to correct an astigmatism, which is the term used to describe an irregularly shaped cornea.
These numbers represent diopters, units of measurement that describe the optical power of a lens. A plus (+) sign in front means you are farsighted; a minus (-) means you are nearsighted. These numbers will always have a “+” or “-” in front. They’re listed in increments of .25. (For instance, if your prescription says -1.25, you have 1.25 diopters of nearsightedness.) The further away from zero these numbers are, the worse your vision problem is and the stronger your lenses will have to be to correct it.
AXIS explains the degree and direction of your astigmatism. This number is expressed in angle degrees.
PRISM refers to the amount of prismatic power needed to correct double vision, amblyopia (lazy eye), and other eye alignment problems. This number is also expressed in diopters.
BASE indicates the direction of a prism. BU means “Base Up”, BD means “Base Down,” BI means “Base In” and BO means “Base Out.”
In addition, you may also see:
PD measures the distance from the center of one pupil to the center of the other.
ADD refers to the “added” magnifying power applied to the bottom of the lens in multifocal (progressive/bifocal) lenses.
PAL is used in some cases by eye doctors when the ADD for progressive lenses is different compared to bifocals.
Don’t hesitate to ask your eye doctor if you have any questions about the information that appears on your eyeglass prescription. If you’re prescription needs to be renewed, schedule an appointment with Berkeley Eye Center today!