Reading an eyeglass prescription can feel like reading a foreign language. And while it looks intimidating at first, the good news is that it’s easy to decipher once you know how it works. Here’s a quick breakdown of an eyeglass prescription along with examples and how to read it.
Latin abbreviations
Latin class is in session! “Latin abbreviations are often used in optometry and ophthalmology as a short-hand way to indicate how often to take a prescription or which eye we are examining or treating,” says Dr. Nate Lighthizer, OD, FAAO, and EyePromise Scientific Advisory Board Member. “For example, taking an antibiotic drop QID OD means taking that drop four times per day (QID) in the right eye (OD).” Dr. Dagny Zhu, MD, Harvard trained and board-certified ophthalmologist, explains what different Latin abbreviations mean:
OD stands for “oculus dexter” which is Latin for the right eyeOS stands for “oculus sinister” which is Latin for the left eyeOU stands for “oculi uterque” which is Latin for both eyes
What do the numbers mean?
Eyeglasses and contact lens prescriptions come in either positive numbers or negative numbers, Lighthizer says. Positive numbers indicate far sightedness, something eye doctors term hyperopia. Negative numbers indicate near sightedness, or myopia. The second number of a prescription indicates the amount of astigmatism of the eye, and the third number of a prescription is the axis or orientation of the astigmatism. Dr. Yuna Rapoport, MD, MPH, board-certified and fellowship-trained ophthalmologist, explains the definition of these common terms: Sphere, cylinder, axis, and ADD.
Sphere
This is the main number of your prescription and measures how near or far-sighted you are.
Cylinder
The cylinder is the number of your astigmatism and basically shows by how much your eye is shaped more like a football, rather than a basketball.
Axis
The axis shows in what direction the astigmatism makes your eye more steep.“There are sometimes other numbers if you have other medical issues going on like if your eyes turn in or out,” says Dr. Rapoport. “For example, PD stands for Prism Diopters and shows how much prism is in your lens to make your eyes work straight.”
ADD
The “add” of a prescription is the amount of reading power needing in a prescription. The “add” is typically only needed once a patient reaches age 40-45 and above and requires multifocal lenses, Dr. Lithizer states. For example, a prescription that reads -2.50 -1.00 x 180 with +1.50 add means a patient is 2.50 diopters nearsighted with 1.00 diopter of astigmatism orientated at axis 180 degrees with a 1.50 diopters of a near add.
Example eyeglasses prescription
Dr. Brad Brocwell ODand Vice President of Clinical Operations for Now Optics, shares what a typical prescription looks like, using all the terms mentioned above: SPHCYL AXISADD ODPL-1.00 180+2.00 OS-1.50 SPH+2.00
Additional abbreviations you should know about
There are many more abbreviations, but most of them are medical and less optical, says Dr. Rapoport.
Additional optical abbreviations:
SVD = Single Vision Distance SVN = single vision near
Additional medical abbreviations:
IOP = intraocular pressure C/D = cup to disc ratio BID = bis in die (Latin for twice a day) TID = ter in die (Latin for three times a day) QID = quater in die (Latin for four times a day) RAPD = relative afferent pupillary defect VA = Visual Acuity Next, read up on everything you need to know about dry, itchy eyes. Sources:
Dr. Yuna Rapoport, M.D., M.P.H, board-certified and fellowship-trained ophthalmologistDr. Dagny Zhu, Harvard trained and board-certified ophthalmologistDr. Brad Brocwell, O.D. & Vice President of Clinical Operations for Now OpticsNate Lighthizer, D., F.A.A.O and EyePromise Scientific Advisory Board Member
