Get a prescription paper written specifically for eyeglasses. Note: The prescription for contacts CANNOT be used for eyeglasses. Let’s take the following data as an exmaple: SPH CYL Axis ADD Prism Base R (OD) +1.00 -0.50 179 +1.50 2 Up L (OS) -0.50 -1.25 003 +1.50 2 Down PD 64 – OR – R 32 / L 32 OD Right eye, latin for Oculus Dexter OS Left eye, latin for Oculus Sinister OU Both eye, latin for Oculus Uterque SPH Abbr. of Sphere, the degree of correction, it corrects your near or farsightedness. CYL Abbr. of Cylinder, it corrects your astigmatism, it will be 0 if you don’t have astigmatism Axis It indicates the orientation of astigmatism, measured in degrees from 1 to 180. It must follow with CYL. NO CYL, NO AXIS ADD or NV Addition or Near Vision, it is calculated for getting the correction for reading or near vision, it can be used for bifocal or multifocal progressive glasses. Prism Prismatic value, it is needed to compensate for any alignment problems in your eyes. Base The direction of a prism. There are 4 directions, up, down, in, out. PD Pupillary Distance. It’s the distance in millimeters between the center of one pupil to the center of the other. How to measure my PD? Now that you know what these terms mean, you know how to read a glasses prescription, which is the most important part of learning how to buy prescription glasses online. Now you can shop online.