Pupillary Protest

‘Pupillary Distance’ is an ophthalmic term. It means, quite simply, the distance between your pupils. If you wear glasses, then you may remember the optician putting a strange metal frame on you and rotating some markers on the top of it before you have a pair made. This is how they measure your pupillary distance (hereafter, ‘PD’).

The PD is an important measurement, because the curvature of the lens must be centred around your pupil in order for you to see through your glasses without distortion and without potentially becoming cross-eyed.


Opticians in the UK must give you a paper prescription after you have an eye-test. The reason for this is to separate out the process of eye-testing with the process of buying a pair of glasses. Before then, you would have had to buy glasses from whomever tested your eyes – somewhat of an unfair practice.

So the paper prescription allows you to go into any optician to have a pair of glasses made. However, the one thing that opticians are not legally required to put on a prescription is the PD.

This was fine about 15 years ago, because you’d have to go somewhere in person to get glasses made anyway. But ever since the internet gave consumers the power of more information and greater choice, you no longer have to go anywhere in person to buy something.

Therefore, it makes sense to include the PD on the prescription for complete freedom of choice. This creates a more competitive market, removing power from a handful of large opticians and driving down prices for glasses (which are absurdly expensive in most places).

Optician Hostility

The established opticians see this as a threat to them making the absurd profit margins that they currently do. Therefore, they will blanketly refuse to give you your PD if you ask for it, and can sometimes become quite hostile at the mere suggestion that you want them to give you a PD measurement.

In fact, if you look on the internet for optician magazine articles and blogs, the only story that seems to be headline news for them is the PD issue. They celebrate any form of victory (moral or legal) that allows them to hold back their precious PD measurement, and bemoan a failed system and ignorant customers if they are forced to give the measurement.

Their argument is centred around the fact that people who are buying glasses online without the correct PD measurement are risking damage to their eyes (very true), which then the opticians seem to get the blame for, or end up having to ‘pick up the pieces’. This is a shame for 2 reasons:

  1. Buying glasses is a completely separate transaction from having your eyes tested. The optician should bear no responsibility for glasses choice, unless you bought your glasses from them… but,
  2. None of this would be a problem for opticians if they put the PD on their prescriptions in the first place!
My Experience

Last year, I was in the market for some prescription sunglasses. After browsing every major high street optician, I couldn’t find the type that I wanted. However, a look online led me to the excellent sports eyewear website www.rxsport.co.uk. This was where I first became aware of the whole PD issue.

There are tools online to help you measure your own PD using a mirror and ruler/measuring tape, but I wanted to be absolutely sure. Luckily, Rxsport have the option for you to send in some old glasses so that they can gauge your PD from them. This is what I eventually did, but first, I wanted to see how helpful the opticians were feeling.

I firstly went out to visit the optician that made my current glasses (a large high street chain in the UK). Their response was a polite, but firm, “no, we do not give out PD measurements”, after going in the back, presumably to check with the ophthalmologist or manager who subsequently must have said something along the lines of “tell him to piss off!”.

I didn’t expect much from them, but I thought I’d have a little more luck with the optician who actually tested my eyes (another large UK high street chain, but franchised). This was a much longer and more amusing experience!

I showed them my prescription and told them I couldn’t find my PD on it. The boy behind the counter looked at me and asked “So you want to buy glasses online, huh?”. I had no reason to lie so I said yes. Upon which, he scurried back to find the head honcho. He ended up giving me a speech as to how his son (another ophthalmologist at that branch) went to university for years to become highly skilled at what he does, and so he deserves to make money out of me. This may be true, but as I mentioned before, buying glasses and getting an eye test are (or should be viewed as) two entirely separate things.

He then persuaded me that the selection in store was as good as online. Anyone who has bought anything from the internet knows just how wrong that statement was.

I ended up buying my sunglasses from Rxsport, who got my prescription bang on, and sent me 4 different styles that I was interested in so that I could try them on first. And I didn’t have to pay the obscene amounts of money that I would have otherwise.

What can be done?

Firstly, keep buying glasses online! When it becomes impossible for physical opticians to compete, they will either have to lower their price or start selling glasses on the internet themselves. Note that there is nothing stopping them from selling glasses on the internet as well! But clearly, they have no incentive to as long as they can scare consumers into thinking that only the optician can provide the ‘missing link’ – the PD – in order for the proper fitting of glasses.

Secondly (and most importantly in the long run) this is a competition issue that the government needs to address in order to fully separate out the buying of glasses from eye-tests and prescription provision.

Once the optician is made to give the PD on the paper prescription after an eye test, people will be able to get their glasses from anywhere. This was actually the case before the internet took hold anyway, because you had to go in personally to an optician to buy glasses. There was no need to have a PD because it would be measured on the spot. But now that you can purchase glasses virtually, the PD is a natural addition to prescription information.

Including it will drive down prices for the consumer; will increase choice; and fully separate the markets of eye testing (a medical procedure) from the buying of glasses (a consumption decision).

To help send the message, there is an online petition available at:


as well a vast amount of information regarding the PD in relation to legislation and opticians.

Let’s do something about it!

2 thoughts on Pupillary Protest

  1. Do you have any information on the number of people who wear contact lenses? as these are (at least I think) becoming increasingly popular, and so PD isn’t an isssue. Personally, I wear contact lenses, and buy “regular” sunglasses, after trying them on of course.

    • This may be true. However, it doesn’t detract from the fact that the large number of people who choose to wear glasses are being subject to an implicit case of collusive behaviour on part of high street opticians. Also, it’s not only sunglasses. It is glasses in general.

Leave a comment

Time limit is exhausted. Please reload CAPTCHA.