Something might be missing if you decided to take the prescription from your last vision exam and shop online for glasses. The website you chose to order glasses from will ask for your pupillary distance (PD). This measurement is critical for ensuring the lenses in your new glasses line up correctly with your eyes in order to improve your vision.
If you’re new to buying glasses online, you probably didn’t know to get your pupillary distance measurement from your eye doctor while you were there. Since this is a pretty common scenario, people have invented some. . . creative ways to come up with this measurement for themselves.
One Ruler to Rule Them All
Step one: get out your millimeter ruler. What do you mean you haven’t touched one of those since middle school and that math problem about the triangles? Fine. Step zero: go buy a millimeter ruler. You could print one out online as well, just make sure your printer is set to “actual size.”
Anyway, now that you have your millimeter ruler (or piece of paper) in hand, you also need a friend. Hopefully you’ve gotten one of these more recently than that ruler you used in math class. Have them stand about an arm’s length away from you.
Then, they need to measure the distance between your pupils. For best results, they should be wearing their own glasses so they can eyeball (no pun intended) where exactly the ruler starts, right at the center of one pupil, and read the measurement directly at the center of the other pupil. Ideally, they are holding the ruler (or paper) perfectly still over the bridge of your nose as this is being read. Holding your breath might help with this. As they do this, focus your eyes on some spot about 10 feet off in the distance. Staring directly at your friend might creep them out and will mess up your measurement.
Repeat this about three times and average them out to account for either (or both) of you moving. If you’re concerned about the accuracy but don’t want to give up on your online glasses shopping experience yet, there is another way you can try.
Mirror Mirror on the Wall
If you’re more of a lone wolf type, you can actually measure your own pupillary distance, no friend required. You just need to replace “friend” with “mirror.” While balancing the ruler on the bridge of your nose, stand about arm’s length away from the mirror and read the measurement.
What if you can’t see yourself at arm’s length in order to read the ruler (let alone those tiny numbers)? After all, you are doing this in order to purchase a pair of glasses.
Luckily, poor eyesight isn’t an excuse to not know your pupillary distance. You just need a highlighter as well. This time, look at yourself in the mirror and use the highlighter to dot where your pupils are on the lenses of your glasses. Then, you can take the glasses off and read the measurement by putting the ruler as close to your eyes as you need.
So, how to clean highlighter off your lenses? You did use an old pair of glasses, right? Oh well, you’re shopping for new ones anyway.
Or Just Use Technology?
However, the desire for people to measure their own pupillary distance has also resulted in some successful and simple methods as well. There are various ways which use technology to create an objective measurement. Unsurprisingly, measuring your own pupillary distance with the assistance of technology turns out to be both more accurate and way easier than relying on a combination of a friend, mirror, and millimeter ruler.
At the rate technology is advancing in this area, there might be even easier methods of measuring your pupillary distance right on the horizon.
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by Joyce Handzo