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How to read prescription

How to read your eye prescription so you can order your perfect glasses at ease


If you've ever looked closely at your eyeglass prescription, you've probably wondered how to make sense of all those numbers and symbols. Some prescriptions can be written for viewing in distance, others – for reading, office or progressive lenses.


Here's a look at a sample eyeglass prescription and a walk-through on how to read it. Below are examples of alternative prescription formats. Look through these to get a general feel, but don't worry if yours still looks different – so long it has all the essential information, you are good to go!

Each optometrist or ophthalmologist will have their own format for writing a prescription, so yours may not look exactly like the one pictured, but that's nothing to worry about. The essential information should be there, and it should always begin with your full name.

The prescription, written by your ophthalmologist in your eye clinic, will have the same information as the one written in a salon. So understanding it won’t be difficult. Follow our guide “prescription terms”.

Typed prescriptions are generally quite easy to understand, it's mostly handwritten ones that cause problems.


To be easily interpreted worldwide,  eyeglass prescriptions  are written in a standardized format with common notations. Look below to learn more about your SPH, CYL, Axis, Prism, PD, and more.
  • OD (Oculus Dexter – Latin abbreviation) - means the right eye.
  • OS (Oculus sinister) -  means the left eye. 
  • SPH - Sphere this indicates the amount of lens power measured in diopters (in 0.25 steps)
  • (-) - Stands for near-sighted (difficult to see things that are far away).
  • (+) - Stands for far-sighted (difficult to see things at close distances).
  • PD - Pupillary distance (PD): The distance between the center of each pupil, measured in millimeters. It tells the optician where to put the optical center on each lens
  • Cyl/CYL - Cylinder. Only for astigmatism. The amount of astigmatism that is caused by an irregularly shaped cornea, measured in diopters (in 0,25 steps). If there is no cylinder, your eyes are perfectly spherical.
  • ACH/A - Axis only for astigmatism. The direction of astigmatism, measured in degrees (0-180).
  • ADD - Addition. If you are over 40, you are likely to see ADD on your prescription – that's the difference between near and far values. Often the same for both eyes. For multifocal glasses.
  • Prism - Often prescribed when your eyes don't work well as a pair. Not common.
  • Base - Tells the opticians where to put the prism in your lenses.


  • Register for the comprehensive eye examination at an eye clinic.
  • Use the prescription you have.

How recent does my prescription have to be?

It's recommended that your eye prescription is no older than one year. Recommended intervals between eye tests vary depending on your age and health.