Reading glasses prescription: numbers and symbols

If you've ever looked closely at a prescription for glasses, you've probably wondered how to decipher all of these numbers and symbols. Eyeglass prescriptions are written in a standardized format with common indications so that they can be interpreted around the world. Here is an example of an eyeglass prescription and a step-by-step guide to reading it.

Latin abbreviations

You must first take a little Latin lesson to understand eyeglass prescription. Latin abbreviations are often used in health care to write prescription and eyeglass prescriptions. These cuts are becoming less common as state and federal rules and regulations begin to lessen reliance on them.

Get medical information / Alex Dos Diaz

Recipe example

Outside diameter : -2.00 – 0.50 x 180

SO : +1.00 DS

ADD : +1.75 OU

Abbreviations used:

  • OD means "oculus dexter" and represents the right eye.
  • OS stands for Evil Eye and stands for Left Eye.
  • The letters OU stand for "oculi uterque" and refer to both eyes.


Eyeglass prescriptions contain numbers, many, many numbers. That is what they mean.


In our example above, the first number to the right of the OD is -2.00. This is considered the "spherical" part of the recipe. The number on the dial indicates myopia or hyperopia :

  • Typically, a minus sign (-) indicates a negative diopter power lens used to correct myopia.
  • A positive sign (+) indicates a positive power lens used to correct farsightedness.


The next number on the sample eyeglass prescription is -0.50. This number represents the "cylindrical" part of the prescription that measures the degree of astigmatism, which represents the difference in curvature and power between two points on the eye separated by 90 degrees .


The next number is x 180, read as "axis 180". This number indicates the angle in degrees from 0 to 180 that represents the position of the most positive meridian in the eye that has astigmatism when written as a negative cylinder, as in the example above.

For the left eye, you will notice that the "sphere" number is plus one (+1.00) DS. The letters DS refer to the "diopter sphere" and indicate that the correction for the left eye is completely spherical in nature without astigmatism. In other words, the cornea of the right eye is likely to be slightly elongated in shape, while the shape of the left cornea is very close to perfectly round.

Typically, instead of the astigmatism number, they write SPHERE or DS as a placeholder so the prescription reader knows that the doctor has not accidentally forgotten to write down the balloon or astigmatism correction.

Add a number

Finally, the ADD number +1.75 represents the power that must be "added" to the distance prescription to give the patient a clear near vision for near reading and action.

This number is usually not found on eyeglass prescriptions for young men. Although some young people may develop problems focusing close and require additional strength, this generally indicates that the patient needs bifocal strength as they begin to lose the ability to focus close (a problem that usually begins to develop in their 40s)

Many people mistakenly believe that +1.75 is the force required to buy over-the-counter reading glasses. However, you will have to do a bit of algebra to calculate the total power required for single vision glasses.

In the example above, this is -2.00 +1.75 = -0.25. Therefore, the reading glasses prescription for the right eye would be -0.25 – 0.50 x 180. For the left eye, the calculation would be +1.75 +1.00 = + 2.75 SD.

Note that most people have prescriptions, unlike the example shown above, and they generally have the same numbers for both eyes. This example was chosen to show the difference between myopic and hyperopic prescriptions and how these numbers affect the calculations commonly performed by opticians, optometrists, and ophthalmologists.

More cuts

Here are some more abbreviations you may find on a prescription for glasses:

  • SVD – Single Shot Distance (Long Range Glasses Only)
  • SVN : Unified Near Vision (read-only glasses)
  • Sphere : The spherical force has the same force in all the meridians.
  • Cylinder : The cylinder force corrects for astigmatism and represents the difference between the strongest eye force and the weakest eye force, generally 90 degrees apart.
  • Axis : indicates the angle (in degrees) between the two meridians of the astigmatic eye.
  • PS : pupillary distance, or the distance between the centers of two pupils between the eyes. This measurement is necessary to create glasses that are comfortable to wear and optically perfect.
  • Prism : Usually a prism is not prescribed. Usually, a makeover in a specific direction is prescribed in patients with strabismus (strabismus) or other eye muscles or focusing disorders .

Reading a prescription for glasses can be confusing. However, with a little study and practice, you should be able to read your glasses prescription like a pro if you ever need to.

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