Tips for reading your eyeglass prescription
If you’ve ever received a copy of your eyeglass prescription and wondered what to do with it, you’re not alone. Millions of Americans have turned to the Internet to buy glasses online, but many stop short of buying because the confusion lies in what their prescription actually means. It’s not hard to take the guesswork out of your recipe, but many people get lost during the first few steps. Here are some points to know as you read your recipe.
Every doctor writes their prescription differently, but 99 percent of all prescriptions have a few abbreviations to look for: OD, OS, SPH, CYL, and Axis. OD, in layman’s terms, means your right eye while OS is your left eye. In his recipe, even if you don’t see OD and OS written, you can infer that his right eye will always be written as the top set of numbers reading left to right, and his left eye is the bottom set of numbers.
The following set of abbreviations is found at the top of your recipe as you read from left to right. SPH stands for Sphere; CYL means cylinder; and Axis is alone. Sometimes the Axis will be shown with an ‘X’ mark instead of the word. The dial represents the amount of correction you need in diopters to help you see near or far, and the number is usually presented in quarter increments. The number on your dial will always have a plus (+) or minus (-) sign before the number itself. Also, your doctor may leave the area blank, enter two zeros (00), write the word flat, or write the infinity sign – all this means that there is no prescription on the dial for that particular eye. When inserting your prescription online, follow the site’s recommendations on how to complete this number.
Your cylinder and axis always go together and indicate that you have astigmatism. Not everyone will have marks in these sections, but if you have a prescription for astigmatism correction, both the CYL and Axis will be filled in. Just like your sphere, your cylinder will have a similar looking number. The number will be in quarter increments and will have a plus or minus sign in front of it. If you have a number for your CYL, you will also have a number for your Axis and that number will always be an integer. The CYL in one of your eyes can be left blank, have two zeros, the word flat or the infinity symbol written instead. This just means that a specific eye does not need astigmatism correction. Your doctor may also write SPH in the CYL field; is the same as saying flat.
Reading your prescription, even if the fields aren’t indicated with SPH, CYL, and Axis, it’s safe to assume that your sphere will come first, then your cylinder, then your axis.
Another thing to look for in your prescription is the PD or pupil distance. Pupil distance sounds exactly like it should: it’s the distance from the center of one pupil to the center of the other pupil. The measurement is in millimeters and can appear as a whole number, such as 63, or as a set of numbers, such as 32/31.5. It can also look like this: 63/61, which means that the PD for your distance prescription is 63mm and the PD for your near prescription (for near vision) is 61mm. If you see two sets of numbers for your DP, don’t add them together! Simply insert them where prompted.
Understanding your eyeglass prescription isn’t that difficult, but a little extra knowledge can make your online eyeglass shopping experience much easier! Remember, if you’re still stuck and confused, just ask a customer service representative for help!