The $1.99 ruler that measures pupillary distance (so you can order eyeglasses online)

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After you’ve ordered glasses on-line for the first time the vendor usually drops one of these in with your order to encourage future purchases.


In Texas and many other states, when getting an eye exam a doctor is required to make certain wellness checks. These wellness checks work best against an established baseline. So yes, you can sit in front of an auto refractor and get a prescription. There is a descent chance that prescription may be wrong, but workable. (Misdiagnosed astig, night vision issues, headaches)

But guess what it will not see the stroke you had or may be about to have. It will not see the slight bulge that becomes a full detachment when you ride a roller coaster or hit a pothole. It will not reveal you eye strain is not tired eyes, but pre-glaucoma. Eye examines can reveal diabetes, cancer, and many other issues.

Going full political - I do not have vision insurance, so I understand it is an annoying cost that may never be realized (for those that cannot calculate risk). This mentality that I can ignore basic upkeep but have a right to healthcare in the aftermath is enabling the “greed” that is so derided in our society. So if you get your medical devices in the cheapest, least value added way possible, try not to be a whiny mess when it hits the fan. Your failure to prepare does not constitute and emergency for others (or at least it should not).

I am going to grab some BBQ sauce for the coming roasting.


You make some good points, but those kinds of thorough wellness checks are not usually done when someone is getting an eye exam in-store from an optician (which people absolutely should do instead of using an app, preferably from someone with a doctorate). It’s telling about retail-store opticians that they’re usually very reluctant (frequently to the point of hostility) to give out pupil distance along with the prescription.


I usually ask the doctor doing my eye exam to measure my PD, at which time they act perplexed as to why I’d want my prescription to be self-contained and complete, then reluctantly get out the manual ruler which they rarely use. It’s strange that for all the fancy gadgets to measure eye health and refraction the one thing they don’t have is a pupilometer like the opticians use for easier measuring of pupil distance, especially given that PD is a key metric. Seems really weird to leave that up to opticians.

In all states, doctors are required to give you a copy of your prescription. Unfortunately, what is required to be on that prescription is up to the individual states, so doctors don’t necessarily have to put the PD on the script, even if you ask, depending on your state. :frowning: But, so far, no doctor has refused my request to include PD, even Lenscrafter’s affiliated EyeExam doctors. For all that, I’ve never actually mail ordered glasses. Costco services have be relatively reasonable and convenient, leaving me with insufficient motivation to go mail order since trying on frames is pretty critical for me.


I just went through this! Ordered glasses online from Zenni, they arrived a week later & the lenses distorted my vision, due to a problem with the pupil distance. After a lot of back-and-forth with customer service on the phone, the rep agreed to give me “one-time only 100% credit” so I could re-order & try again, re-filing my prescription on their online form. I suspect this happens often with first-time customers. Unfortunately the refund did not cover shipping cost or some extras, so I’m out $10. And I have no confidence that the second try will work any better.

I have had success ordering online with Warby Parker; at that time they required a scan of my prescription, rather than allowing me to fill out a form myself. But I can’t afford them these days. And unfortunately the optometrist/optician I used to go to no longer accepts Medicare.

Meanwhile I’m stuck with glasses broken at the bridge, wrapped together with copper wire. Something about the plastic used for eyeglass frames resists any glue I have tried, & I’m afraid to try punching holes with a hot needle to tie the two sides together.


I needed one of these a while back.

I did not want to go driving around looking for something like this so I made do with a piece of letter sized paper and used Algebra to derive the measurement.

Who says you are never going to use math?


I’ve always had good luck with Zenni, for over a decade. And the optical chain (Pearle) doctor has checked them and verified that they were properly made. (At least on the cheaper ones, the frame quality is about halfway between optician and dollar-store readers.) If you don’t tell them the correct PD, that’s your screwup, not theirs. They do throw a (cardboard) ruler in with an order. But when I couldn’t find one, I measured with a good ruler in the mirror, standing back about 3 feet to minimize the effects of being too close (parallax and crossed eyes). If your eyes were different distances from the center, you’d really want an IP ruler to measure the offset, though.

I expect these rulers are plastic, and more durable than cardboard.


It’s actually $5.49 as they charge $3.50 for shipping.

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Yyyyyyyeah, so, at the risk of being accused of gasp disappointment, this is pretty bassackwards advice.

You definitely can make one of these yourself and save $5.49 plus a few grams of carbon emissions. (Or you can hold a ruler up to the bridge of your nose and have someone else read off the measurement. It feels like it shouldn’t work, but it did for me.)

You definitely should not skip out on your eye exam if at all possible, whether you think your old prescription is fine or not. Yeah, it’s a hassle, and yeah, medicine is all a corrupt racket, but the optometrist has a non-trivial chance of catching things that will extend the useful lifetime of your eyeball or your body as a whole. Besides which, the price of that app is in the vicinity of the low end of a sliding-scale vision checkup if money is the issue.


In the UK at least, high street opticians are required by law to give you a copy of your prescription once you’ve paid them for an eye test.
But they are NOT required to give you your pupillary distance or other physical measurements; and plenty will hold these measurements to ransom so that you ‘have’ to buy your glasses from them at a brutal markup, and not online. It’s a shitty practice. I’m all for paying fair whack for eye tests (my RX is strong and complex, and I’ve worn glasses since I was five); but measuring my face and then refusing to tell me the answer is miserable cough David Clulow cough.


It is one of the issues that comes up for Optometrists (opticians cannot prescribe glasses they just fit them.) MD and DO cannot (if I remember correctly) fill their own prescriptions this was due to an inherent (and often exploited) conflict of interest. Someone further down mentioned their low quality glasses are broken. OD often have to deal with these patients coming it to fix them or complain that their glasses built from the OD’s prescription are not right (so of course the OD messed up.) The OD is encouraged to keep the patient in house, but independent OD’s are infinitely less pushy about this. In Texas, if the dispensary is in the OD’s office they are “independent” if you have to leave their office and go next door then they are not independent and are hire by the “retail” to feed people to the lense store (big box store, lens crafters/masters).

Your PD is part of your medical record (not prescription), in Texas. And someone has pointed out it is just a metric ruler, you do not need and special version.

I’m sure that’s true. I also am sure that most DOs working out of an eyeglass retailer’s shop (as many if not most in the U.S. do to save on expenses) have no problem with the conflict of interest inherent in not providing PD (vital to grinding the lenses and ensuring that the prescription, y’know, works) and fitting measurements unless the patient promises to buy from said shop.

It’s a BS business practise that has nothing to do with medicine and that needs to stop.

That’s an understatement.

Would you buy or order prescription glasses without specifying the PD? If not the practical distinction between medical record and prescription in this case is non-existent. In any case it takes 30-seconds for the OD to do anyone the courtesy of doing the measurement and writing it down on the prescription form (which usually has a space ready for it).

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Every DO covered by my insurance works out of an eyeglass retailer shop, or is attached to it, and the last three I’ve gone to have flat-out refused to give me my PD. But at this point I’ve been using Zenni for about four or five years, and whatever PD I’m using works great.


Biometric monitoring. Probably WiFi enabled.

I was just explaining some of the various forces and considerations that affect this situation. The reason the PD not being part of the prescription is important is that in Texas the PD is not required to be done. If it is done they do not have to automatically provide it. Since it is part of the medical record it has to be provided to you if you ask (and pay relevant fees).

Also OD are optometrists and Do are doctors of osteo-something like MD’s.

The doctors that are employed by opticals are often ones that are newer or just don’t want to deal with retail. Some don’t like medical as they see more correction usually. Technically they are not employees just leasees and cannot force anyone to use a specific diapensary.

Some of that comes down to the client/customer focus. My eye doctor would do and give the PD if asked, but they are independent and develop client not serve one off customers (or at least that is their mentality).

If you are in the states, they may be breaking the law. This is managed by state though the medical record law may be federal.

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In most states (I think), doctors aren’t required to measure PD or put it on scripts, so even if they have to give you your script to leave with by Federal law, or a print out of your medical records, they don’t have to measure your PD in the first place, and don’t. It certainly seems ridiculous, and assume this state of affairs was lobbied for by the traditional retail optical dispensing industry.


Partly it is that measuring PD is the responsibility of the fitting party. It is not even a medical process. I get it is annoying though and my doctor does it and moves on. It is better to do than alienate clients. Though they get pretty annoyed when people bring in their busted up discount frames and want her optical to service them or explain the poor build out.

I have a family member optometrist who is the proud new owner of a sight shop. My son ordered his glasses online, and I asked him about the pupilary distance measurement. He said that young folks’ brains can often compensate for an aproximate measurement, but not the rest of us.

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