How to Read a Glasses Prescription

Your eyeglass prescription may be difficult to decipher, but there are a few simple tricks you can use to help you decipher what the numbers and letters mean.

First and foremost, take note of the Latin abbreviations for oculus dextrus (right eye) and oculus sinister (left eye). Your vision prescription may also include a column marked OU which denotes "oculus uterque," or both eyes.


Your glasses prescription is a comprehensive collection of information about your eyes. It uses terms and abbreviations like OD (left eye) or OS (right eye), with possible inclusion of OU for both eyes.

Your prescription's sphere power, indicated by SPH (Sphere Power Hours), indicates how much lens power you require for clear vision. A minus sign next to this number indicates nearsightedness while a plus sign signifies farsightedness. To find out about the different models of prescription glasses, you can visit the Optical Center website.

Cylinder power, often written as CYL on your prescription, is the amount of lens power necessary to correct astigmatism. It always follows sphere power in a glasses prescription and may include either a minus or plus sign to indicate what type of correction is needed.


One of the most essential components of a glasses prescription is its axis. This number tells your optician which direction they must position any cylindrical power in your lenses (required for those with astigmatism).

Axis numbers are usually between 1 and 180 degrees, with 90 being vertical position and 180 being horizontal.

A higher number does not indicate your prescription is stronger; rather, it simply indicates the position of your astigmatism. However, if this number is higher than usual, you might want to consider getting an axis correction lens for better vision - especially if you are nearsighted or farsighted with astigmatism.


Your prescription is composed of Latin abbreviations, numbers and mathematical symbols that help opticians and eyeglass lens makers determine which type of lenses you require. By understanding these numbers, ordering glasses online becomes faster and easier.

When reading your prescription, three numbers are essential to comprehend: the sphere (SPH), cylinder (CYL) and, where applicable, an axis number.


When visiting an optometrist or ophthalmologist for an eye exam, they typically hand you a copy of your prescription. With so many letters and numbers, it may be difficult to decipher what all the data pertains to.

Your prescription will often feature the Latin abbreviations OD and OS, representing oculus dexter (right eye) and oculus sinister (left eye). Sometimes you'll also see OU, standing for oculus unitas (both eyes).


An eyeglass prescription is a document that clearly specifies the type of spectacles you require. Unfortunately, reading one can be daunting if you don't know what to look for.

After your eye exam, an optometrist or ophthalmologist will issue you a prescription for glasses or contact lenses. This prescription includes Latin abbreviations, numbers and mathematical signs that describe your eyes' shape and how vision needs to be corrected.

Your prescription's initial number indicates whether you require distance correction (needs near correction) or nearsightedness (needs distance correction). It is usually written with either a plus sign (+) or minus sign (-).


Your glasses prescription will display the abbreviations OD and OS for right and left eyes respectively. These Latin abbreviations stand for oculus dexter (OD) and oculus sinister (OS).

Your prescription diopters (eyeglass lenses) indicate how much correction is necessary to see clearly. The more diopters you have, the stronger your vision will need to be corrected.

Your prescription will also have a number called the axis, which indicates where the CYL correction will be applied on the lens. This number ranges from 0 to 180 degrees.