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PD (Pupillary Distance) measurement has been one of the most common threads in the 20 months that GlassyEyes has been around. Dispensing opticians appear to see it as a key to continued profits, and hold this very simple number (at least in a traditional single vision script) over our heads in order to over pay in their stores.

PD measurements aren't difficult to obtain as has been discussed over and over. There is nothing magical about them and optometrists themselves have debated over the accuracy of machines designed expressly to provide PD. I did my own. I measured my wife's uncle and he's thrilled with the result. There are many different ways to do it and you'll see each of them employed in professional environments as well as in bedroom and bathroom mirrors around the world.

Forum regular, IMQ came across a thread at the beloved Optiboard ( that has a number of interesting comments from supposed health care providers concerned more with profit over providing accurate (and complete) prescriptions.

"LeighLee" starts things off with an alert to all opticians:

Our OD called the Georgia Society of Optometry, and was told that we HAD to give the PD as part of the prescription if we do a refraction as part of the exam... We have never included PD as part of the refraction before. So we have never included a PD along with the RX that is handed to the patient... I am concerned that if we are forced to give the PD, more and more of our optical patients will go elsewhere, like ONLINE!!

"Fezz" would just as soon be snarky when providing the PD:
Write it down in inches and forget about it!

"MarcE" sees providing the PD as a big problem:
Yes Fester, including a PD on an Rx is terribly shortsighted.
This is not a small issue - it could be our biggest problem going forward.

"Against the Rule" makes the only solid point in the thread thus far:
If giving out PD's is going to bankrupt your practice, your practice ain't gonna be around long anyway.

I find all of this very disconcerting. I think, as a group, the people who use and contribute to this site are VERY concerned with their overall eye health. One thing is certain, I'm much more able to afford to get my eyes checked regularly now that I'm not going to have to tack on $400 for a new pair every time I get them checked. I'm also not wearing old, weak prescriptions any longer. Why would I? I can spend as little as $8 and get something that allows me to see the way I should be seeing when things change. I don't have to budget for this any longer. When I feel like things are starting to get a bit blurry, I'm in (paying these people who seem to want to inconvenience me) to get an updated prescription and make sure my eyes are healthy.

I think the real winners when everything shakes out in this field are going to be those professionals who actually act as professionals should. Give me what I've paid for and I'll keep coming back. If you can figure out a way to get the prices down on the glasses in your store (yes, I'll even wait a week or two), I'd gladly give you a shot.

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At July 2, 2008 at 8:50 AM Anonymous said...

Here's how I measure my PD. It works great, and is easily repeatable.
Take two post-it notes. With a pin create a tiny pin hole in the lower left corner of one and the lower right of the other.
Now affix them to something solid so you can look through the pin holes like glasses (I used a cd case).
Either with your glasse on, or off if you can see, look at something far away, and adjust the pinholes closer or farther away from each other until you seem to be looking through one hole.
Now measure the distance between the pinholes. That is your PD.
Try it again for something close, like reading a book, you'll notice that it is less.
Now take the post-it's off and do it again, you should get the exact same results every time.

I learned this from the forum here. I tried the marker on the glasses thing but got different results each time. This Post-it trick seemed SOOOO much easier.

At July 2, 2008 at 1:29 PM Unknown said...

I love your site as it is, but if you were going to add only one feature a "Friendly Opticians" list would be excellent. I want my husband to order new glasses, but I don't know where to send him since the place I went to didn't disclose PD.

It would also be nice to give a boost to Opticians without dispensaries.

At July 3, 2008 at 2:01 PM Anonymous said...

Thank you. I'm glad this is a concern for other people. I just went through this yesterday. I was at my eye doctor for a medical reason and asked for them to give me my prescription. They gave it no problem, but then I noticed the Pupillary Distance wasn't there so I asked about that. The person I was talking to was about to check it for me but then came back with another person and they looked at me kind of funny and said that "they should be able to do that" wherever I go for glasses. It became a little awkward so I just went with it. At that point I wasn't about to tell them I was going to buy glasses from a web site for much cheaper.

At July 3, 2008 at 2:33 PM Unknown said...

Man, I had no idea this was such an issue for people. I just looked straight ahead in a mirror, marked where my pupils were with a dry erase pen, then measured the distance between the dots. Just to double-check, I had a friend mark my pupils for me (THIS IS EXACTLY THE SAME WAY THEY DO IT AT MY EYE DOCTOR'S OFFICE) and got the same result. I did it a few times both ways and got a slightly different result each time, but they were all within 63-65mm. I've gotten several pairs of glasses from several different websites with a 64mm PD and had no problems.

I think it's pretty crappy that optometrists won't give out this information, but it's not like you need any special tools or training to do it yourself. If you have a dry erase pen, a friend and/or mirror, and a metric ruler, you have all the tools you need. Sheesh.

At July 10, 2008 at 4:55 PM Anonymous said...

After measuring w/ a ruler and becoming frustrated and then realizing that PD is different for near and far, I nearly gave up. Then I found this page through a google search:

which in part reads:

"You should also be able to get your PD from your previous eyeglass supplier, this figure does not expire with age,they have to give it to you by federal law as well as your full prescription, it is your property."

I called the three places where I bought glasses over the last eight years. All three gave me the numbers; only one chain store was grumpy about it. The final one--great guys in Vermont--had measured both my near and far PDs and gave me both. That allowed me to get my glasses online. (Which came in today and appear to be the wrong prescription, but that's another story!)

At July 10, 2008 at 11:01 PM Anonymous said...

Due to a few medical conditions I seen a eyedoctor once a year at a local ophthalmology hospital. The last time I was there I was telling him about zennioptical & how I had to figure out my PD. He said the avg person is about a 62/63, so there ya go.
BTW I now have 5 pairs from them and a pair of prescription sunglasses.

At July 15, 2008 at 7:38 PM Anonymous said...

I am amazed and saddened to hear that some optometrists/opticians/opthamologists/etc. would try to create vendor-lock with something as petty as withholding pupil distance.

My eye doctor is actually located in a local "discount" optical chain, and had no problem when I asked for my PD. He was actually interested, and asked me to stop by and let him know what my experience was like ordering online for the first time.

At July 15, 2008 at 9:54 PM Anonymous said...

The only PD concern I really have is that I'm trying to buy a pair of prescription sunglasses and an extra pair of glasses for my 2 year old (who has an rx of -10.00!) and it seems pretty much impossible to get that measurement since he has no idea what I'm doing and is more interested in whatever else is going on the room.

I guess I'll try calling the place where we got his first pair of glasses and seeing if they'll give it to me. I kind of spied on the lady who was measuring it and made a mental note of what it was. That note is long gone. I hope they dont give me a hard time.

At July 16, 2008 at 8:17 PM Unknown said...


I use the same method with the post-its, and it works perfectly. My first pair I was off by 1mm because I tried to use a pen and measure with dots on old glasses. Ever since the post-it method it's been perfect!

At July 20, 2008 at 7:27 AM Anonymous said...

Is there a difference between distance pd and reading pd? If there is, how can I obtain the reading pd?

At July 21, 2008 at 9:01 PM Unknown said...

I just went to Costso in Fairfax, VA this week for an eye exam. I explained what i needed (PD) and they had *no* problem with it. Yay!

At August 5, 2008 at 8:53 PM Anonymous said...

I've had trouble with more than just finding out my PD. I went to a local discount chain (ValuVision) and got my exam. All smiles, of course. Then I drop the bomb: I want my prescription.zbx

Suddenly, it takes about twenty minutes for the doctor to find my prescription (I had barely left the exam room!) and give it to me. I take it home, and discover what?

He only gave me half of it.

I'd laugh at the audacity if I weren't so annoyed at it.

At August 27, 2008 at 8:31 PM moocifer said...

Here's an idea: Try using your digital camera to derive a measurement.

I haven't tried this, but it seems like it should work, especially with small children, because you could get him/her to focus on different things while you take several pictures, and check the distances later).

a) mark a 2 cm line on a sticky label.

b) put it on your forehead (or your child's forehead

c) stand in front of your child the necessary distance (people are saying 40 inches away, but whatever the appropriate distance is that the eyes should be focused on.

ask the child to focus way behind you in the distance if that's what the pupillary measurement protocol calls for.

snap a digital photo or 5 of them.

blow them up on your computer screen and measure the distance on the screen between the centers of the pupils.

proportion the measurement to the known distance of the 2 cm mark on the forehead. (if the mark measures 7.3 mm on the screen, and the measured pupillary distance is x, the actual(derived) pupillary distance will be (length of measured pupillary distnance on the screen) / (length of forehead mark as measured on screen/2).

you get the idea.

What do you think??

At August 27, 2008 at 10:50 PM Ira said...


The logic works for me. One of these days, I'm going to line up all of the home versions of PD measurements and have some uninitiated run the tests and compare against a known value.

At August 28, 2008 at 10:24 AM Unknown said...

I have followed a couple of the threads re buying glasses on-line and measuring your own PD with interest. I was an Optician (state licensed) for 20 years and worked with everyone from discount chains to small boutique Opthomology practices. While I never refused to give a person their PD when asked I generally did not volunteer the measurement unless asked. It is a business - there is overhead, payroll, etc. Opticians for the most part are not highly paid. However, that's not why I write. If a person wants to take their own fine.
I do however strongly disagree with the mother of the 2 year old with a -10.00 doing this herself. The PD DOES matter! Especially with a script like that. Plus your child has grown, and they will be moving around. The stronger the script the more prism you will induce with a PD that is off! As well as vertex distance and paralax(sp?)For heaven's sake have a professional do it. If they balk offer them $10 bucks or so. You want to play around with your vision its one thing, but this is your child! BTW - not in the business anymore - after 20 years decided to go to law school and fight the health insurance companies.

At August 28, 2008 at 9:59 PM Anonymous said...

PD is VERY important if you are ordering glasses with progressive lenses because the in-focus portion of the lenses is a narrow column down the middle of each lens and you want both eyes to be in focus when looking straight ahead. I measured my own PD in a bathroom mirror that went up to the corner of a wall. I rested my head against a door frame to fix the position, closed the right eye and marked the middle of my left eye reflection on the mirror with a felt point marker, then repeated on the right and measured the distance between the marks. Repeat once or twice to make sure you get the same measurement.

At August 29, 2008 at 8:02 AM Unknown said...

Yes Anonymous, PD is important w/ a PAL. I did not state that it was not. What I said was that w/ a -10.00 in a 2yr old you need to, not should, you need to make sure the measurements are as accurate as possible - unless you really are willing to trade your child's vision for a $10.00 savings. That includes PD, vertex, OC height, overall fit, material. If you are not comfortable with the person you are dealing with go somewhere else, shop around - however, we are talking about a 2 yr old. They can't verbalize whether the vision is crystal clear or not. Heck, they don't even know that they can't see. How much is your child's accurate vision worth to you?

At October 22, 2008 at 3:12 PM Anonymous said...

The post it trick really works well. For an even easier time I find that coloring on and around the pinhole area with a black marker makes seeing an object even easier. Try it!

At November 23, 2008 at 8:38 AM Anonymous said...

I used a large needle to poke 2 holes in some black construction paper. I started with the PD given to me by my OD. It turned out to be my NEAR PD not my FAR. Adding 5mm to the 69mm got me to 74mm. Perfect PD for 20+ feet. Be sure the holes are at the same distance from your eyes as your glasses will be.


At November 23, 2008 at 9:42 AM Ira said...


I didn't like where this was going at all from the start -- "I used a large needle to poke 2 holes in..."

Imagine my relief when it turned out to be paper. ;-)

At December 4, 2008 at 7:02 PM Anonymous said...


Too funny!

I've just ordered a pair of progressives from EyeBuyDirect using the 50% off coupon and spec'd with my measured PD's --- will report back when they get in.


At January 6, 2009 at 1:38 PM Anonymous said...

My eye glass guy just gave me my PD which he said was "f 33.0/32.5 N 30.5/29.5" Can someone tell me what this translates to on an online order form where I need to select between 50-75? Thanks!

At January 6, 2009 at 2:12 PM Ira said...


That's 65.5 for the far and 60 for the near.

If it were me, I'd go 65 for the far -- but you can, and should, certainly add the actual numbers as you've entered them here in the order comments.

Good luck.

At March 20, 2010 at 11:57 AM David A. Carlson said...

When I told my optemtrist that I wanted my pd to buy glasses online, he walked out with me when the exam was done to the eyeglass selling portion of the clinic and directed one of the sellers to measure it with their high tech thingy and put it down on the script he just gave me (the full version as I am moving to bifocals - I like that kind of service - probably why the 4 eye glass wearers in my family will be back to him for years and years

At April 11, 2010 at 2:01 PM Anonymous said...

I too am having trouble obtaining my PD from the optician/optometrist at Target in Washington State, it outrages me that they are so selfish over this trying to strong arm me into purchasing from them. Does anyone know where i can go online to get proof that they MUST give it to me? i would just love to waltz back in there with documentation from the Attorney General and see what they say then!!


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