A Dispensing Optician’s Guide to Reading Eyeglass Prescriptions

Anyone who has seen an eyeglass prescription knows that they can be quite tricky to read. While it is true that doctors are known for their chicken-scratch handwriting, even a clearly printed prescription requires dispensing optician training.

Eyeglass prescriptions contain a series of numbers and abbreviated terms. To the untrained eye, the abbreviations OS, OD, SPH and CYL may look like call signals for airports, but to an optician these terms actually indicate various parts of a prescription.

If you are planning to pursue a dispensing optician career, you will be required to read and interpret prescriptions in order to help customers select appropriate eyewear. Read on to learn more about some of the most common items found on prescriptions.

Dispensing Opticians Understand Left & Right Eye Abbreviations

A few common terms that you will definitely come across during your dispensing optician career include “OS” and “OD.” These are abbreviations for the Latin terms; oculus sinister (left eye), and oculus dextrus (right eye). While most eyeglass prescriptions contain a column for each eye, others may have a single column marked “OU.”Experts know that this is the Latin abbreviation for oculus uterque, which means both eyes.

During your dispensing optician courses, you might learn that information regarding the right eye (OD) typically comes before information on the left eye (OS). This is because when an optometrist is facing a patient, he or she will assess the right eye first and the left eye afterwards.

The Small Symbols that Make a Big Difference in Eyeglass Prescriptions

Plus (+) and minus (-) signs will always be found before a number on any eyeglass prescription. They may seem small and insignificant, but any expert holding a dispensing optician diploma knows that these symbols play a huge role in determining the type of lens a patient requires.

A plus sign before a number represents farsightedness and a minus sign means nearsightedness. The numbers featured on every prescription represent dioptres, which are the units of measurement used in optometry. Usually, the higher the dioptre is, the thicker the lens will be. However, if the number follows a minus sign, the lens will appear thicker in along the edges, whereas if it follows a plus sign, the center of the lens will be the thickest area.

Certified Opticians Recognize All Terms on an Eyeglass Prescription

Industry professionals know that prescriptions are full of abbreviations and other terms. Here is a breakdown of what some of these terms actually mean:

SPH refers to the sphere. This particular section indicates the amount of lens power, measured in diopters.

CYL refers to the cylinder. The cylinder represents the amount of lens power needed for astigmatism. In some cases, optometrists will leave this area blank, since not all patients have astigmatism.

Axis It’s important to note that anytime there is a cylinder indicated on a prescription, there will be an axis value. The axis described the position of the astigmatism and is defined with a number from 1 to 180.

Are you interested in learning more by enrolling in dispensing optician courses? Check out our online diploma program for more information or to speak with an advisor.

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Have Questions?

Ask a Program Advisor!

Do you live outside of Canada? Inquire on our international website!

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