The abbreviations and numbers on your eyeglass prescription describe the type and strength of lenses you need, and the degree of nearsightedness, farsightedness, or astigmatism in each of your eyes.
Regular eye exams are an important part of keeping your eyes healthy and your vision sharp.
At your eye exam, an eye doctor will check for any signs of eye disease. If your vision needs to be corrected, you’ll be given a prescription for eyeglasses or contact lenses.
Eye prescriptions can be hard to decipher, though. They usually contain an assortment of numbers and letters that can be confusing if you don’t know what they mean.
We’ll help you make sense of the abbreviations and numbers that may be included in your eye prescription while explaining how prescriptions vary depending on your vision issues.
What do eye prescription abbreviations mean?
Your eyeglass or contact lens prescription will contain various abbreviations, many of which will be followed by numbers.
Here’s a summary of what these abbreviations mean:
A glossary of eye prescription abbreviations
- ADD stands for the additional lens power needed to make it easier for you to read. This number is seen on prescriptions for reading glasses or the lower portion of bifocal or progressive lenses.
- Axis is a number between 1 and 180. It indicates exactly where the astigmatism appears on your eye.
- BO, BI, BU, BD stand for base out, base in, base up, and base down. These abbreviations tell the eyeglass manufacturer exactly where to position the prism on eyeglasses to correct double vision.
- CYL stands for cylinder, or the amount of astigmatism in your eye. The cylinder and axis together help correct astigmatism.
- DV is an abbreviation for distance vision. This number indicates whether you have nearsightedness or farsightedness.
- NV stands for near vision and indicates how well someone can read or see up close. Doctors typically use a handheld card containing letters or numbers to determine this measurement.
- NVO stands for near vision only. Doctors use this for read-only lens prescriptions (bifocal or progressive) to make reading easier.
- OD means oculus dexter, or your right eye.
- OU stands for oculus uterque, or both eyes.
- OS is oculus sinister, or your left eye.
- PD stands for pupillary distance. Monocular PD is the distance from your pupil to the middle of your nose. Binocular PD is the distance from one of your pupils to the other pupil.
- Prism is used if you have double vision. It indicates the amount of prismatic power your glasses need to correct for differences in the alignment of your eyes.
- SPH means sphere, or the power of the lens that will correct your eyesight.
