Perhaps you already picked out the perfect pair of Felix Gray prescription computer glasses. The Nash frame, the Hopper, the Turing, the Jemison? The bridge looks right. The color is amazing, and you can’t wait to try out the Blue Light filtering technology in front of your computer and phone screens.
But first, you need to place your Rx order, and part of that means understanding pupillary distance (or PD).
What is PD?
Pupillary distance (or PD) is the distance between your pupils and it’s measured in millimeters (mm). Remember, your pupils are the dark circles located within the colored iris of your eye. The aim of PD is to line up the center of your lenses with the exact center of your eyes. Makes sense, right? Without a good pupillary distance measurement, your prescription glasses might do more harm than good. You could experience blurriness, headaches, double vision, nausea, or other eyesight issues if the measurement is off.
Make sure to request that your doctor includes your pupillary distance (PD) with the prescription. Having your pupillary distance (and the exact measurement in millimeters!) allows our team to locate the optical center of your lenses so that your prescription is correctly placed. With this pupil detection and location we’re able to offer you the best prescription glasses solution.
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Reading PD on your prescription
A standard prescription eyeglasses includes several common terms - sphere, cylinder, axis, ADD. What is pupillary distance? Where can you find it?
Let’s start with a few of the basics. When you look at your prescription, you’ll see several numbers under “OS” and “OD”. These are abbreviations from the Latin oculus sinister for the left eye and oculus dextrus for the right eye. You may also see “OU” on your prescription which pertains to both eyes, or oculus uterque.
When you find the PD, you may see either one number or two numbers depending on the type of prescription you have (single-vision or progressive/bi-focal) and how the PD measurement was taken. At this time we at Felix Gray only offer spherical value (SPH) between -6.00 and +4.00 up to a -/+2.00 cylinder (CYL) and at the moment don’t offer bifocals for ADD powers, prisms, multifocal lenses, progressive lenses, or high myopia outside of our current range.
There are two primary ways eye doctors measure PD, binocular and monocular. A binocular PD is the distance from the center of one pupil to the center of the other eye pupil. A monocular PD is the distance from the center of one pupil to the center of the face. In this case, there are two PD numbers reported, one for the right eye and one for the left. It’s used when the eyes are not set symmetrically, such as having one eye closer to the nose than the other.
If you have a bi-focal or progressive prescription, you might have two numbers reported, one for reading and one for distance. The reading PD is often 3 mm less than the distance PD.
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How to measure pupillary distance
At the eye doctor’s office, PD is measured using a pupillometer device, though there are a variety of techniques that optometrists or opticians use to get an accurate measurement. The PD is an important part of your prescription (can be for your myopia prescription or hyperopia prescription), but it may not appear on your written prescription. If your eye doctor didn’t include the PD measure, there are a few things you can do to measure pupillary distance.
Felix Gray offers an online PD measurement tool. To use it, you will just need to follow the directions and snap a quick photo from an arm’s length distance with a standard size credit card under your nose. This helps us get an accurate millimeter measurements so we can correctly place your prescription into the lens. Once you send us the photo we take care of the rest!
Request the PD measurement from your optometrist. Most eye doctor offices are familiar with patients requesting the PD to order their own eyewear, though some are hesitant to provide it if they fear you won’t purchase from them. Keep in mind, some states such as Alaska and Massachusetts, require the PD measurement on prescriptions.
Visit an eye care provider (ECP or eye care professional) to have your pupillary distance measured. Some ECPs may not charge you at all or may charge a small fee.
How to measure PD with a friend or in the mirror
As a last resort, you can measure your PD with a millimeter ruler (or a PD ruler!). The best option is to have a very astute friend help you, but you can also look into a mirror and try on your own.
First, stand about 8 to 10 inches from a mirror and hold a ruler horizontally up against your brow or directly under your eyes. The best bet is to use a ruler with millimeter measures, or you can use centimeters and multiply your results by 10.
Close your left eye and line up the zero end of the ruler to the middle of your right pupil. Open your left eye and close your right. Read the measurement that lines up to the middle of your left pupil. This is your PD. If you measure your own PD, we still recommend using our PD measurement tool to ensure the most accurate measurement for your prescription glasses.
What is a normal pupillary distance?
Once you have your numbers, you may wonder if you are on the right track. One way to double check is to make sure you fall somewhere in the typical PD glasses range. The average pupillary distance for adults is between 54 and 74 mm. For kids, the average is between 41 and 55 mm. Remember, these are averages so your number may not fall within these parameters, but should land somewhere between 41 and 80 mm.
You can look through our site and check out our assortment of Blue Light filtering glasses to help make Digital Eye Strain (also known as Computer Vision Syndrome), glare, and blurred vision a thing of the past. We offer non-prescription glasses, prescription glasses, reading glasses, and sunglasses in a variety of different frames and colors. If you have myopia (or nearsightedness) and need glasses to improve your distance vision, you can either wear contact lenses with our non-Rx lenses or you can opt for our prescription glasses.
Once you learn your PD, you can pick out the pair of glasses you want and then add them to your cart. You’ll be prompted to provide your glasses prescription (and PD!) information once you start checking out. If you already placed your Rx order you can send us an email at hel[email protected] with your order number and we’ll make sure to get everything on it’s way. We try and make ordering glasses online as easy as possible so feel free to reach out if you still have questions. We’re always here to help. Contact us today.
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