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Eyeglass prescriptions are intimidating. They use lots of obscure abbreviations and puzzling numbers that have the capacity to improve your vision. And that, if we’re being honest, might as well be witchcraft. But fear no more! We put together a short guide that should help you decipher your very own optic magic spell. Understanding the basics of your prescription It is very common (and perfectly normal!) for each eye to have different corrective needs. That is why your prescription has to specify which eye is in question. The left eye is identified as OS and the right eye as OD (from the Latin Oculus Sinister and Oculus Dexter). Farsighted, nearsighted, or astigmatic? The sphere (SPH) refers to the degree of power required for distance or reading glasses. This type of power is distributed evenly all over the lens, and the number will be accompanied by a plus or a minus sign to indicate, respectively, hyperopia (farsightedness) and myopia (nearsightedness). If your prescription needs to correct farsightedness in addition to nearsightedness, it will be marked as ADD, as in “add power”. Pretty straightforward, right? The cylinder (CYL) refers to the power required to correct astigmatism. Different degrees of power will be assigned to different areas of the lens, along an AXIS. The number associated with the axis refers to the degree of rotation necessary to distribute power with precision. What is pupillary distance? The pupillary distance (PD) is the measured distance between pupils. This information is necessary to align the centre of your lenses with the centre of your eyes. If you’d like to learn more about pupillary distance, we’ve got a post for that! What is prism correction? Finally, some prescriptions include a power ..... Continue Reading
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