The S refers to the "spherical" portion of the prescription, which is the degree of nearsightedness or farsightedness discussed above. The C refers to the "cylinder" orastigmatism, and can be a negative or a positive number. It measures in diopters the degree of astigmatism that you have....
Surprise! Here’s another eye abbreviation you might see on your prescription. OU is an abbreviation foroculus uterque, which is Latin for “both eyes.” Glossary of Eyeglass Prescription Abbreviations and Terms In addition to OD and OS, your eye prescription is bound to feature several other ...