How do you find out the ocular center when ordering glasses online?

I also want to cut down on the cost of glasses by buying online. Between my daughter and me, we may need a total of 70 pairs of glasses (from -5 myopia).
But without putting a frame on my face, how can I know the ocular center? (I got near and far pupillary distances from the optometrist.)

If this is your first time getting glasses online, you will first have to make sure that you get the right size frame. You can measure your existing frames and see if any of the models offered are the same size. Most sites will show you which measurements to take. If you are ordering diffs, use the near pupillary distance given by the opto and put that into your order prescription. If you are ordering norms, use the far PD. There is not much you can do about pupillary height, and this is a bit of a gamble. If you have a fairly standard nose, this is likely to be close to correct.

You are probably going to order diffs first, and this will give you experience with the frames. If they fit well and give you a good optical centre, stick with them for the whole journey. You can have a mark put into the inside of the arm to differentiate your reductions. D1, D2, D3, etc. for reduced diffs and N1, N2, N3 etc. for reduced norms. Zenni does this, but I am not sure about other suppliers. If not, make the marks yourself.

Some people like to play around with different frames, but this could be a bit of a gamble each time.

Good luck on the start of a long (and rather expensive) journey for the two of you.


@Ursa Thank you so much for your detailed advice! We got our first pairs at Costco because we obtained reduced prescriptions from the optometrist (she promised to google EndMyopia). But I will switch to online for future pairs.
I am eager to make progress because I want to convince people around me that myopia is reversible so that they can join us and avoid surgery or getting worse. I’ve introduced EndMyopia to a few people considering surgery or getting first glasses; but they are still reading.


Pupillary hight is a gamble. I asked several online sellers about how they estimate the correct height and the last one wrote back “we put in the height where it makes sense”. That gave me a laugh :wink: Another seller told me that if the height is off they will change it for me. Another said i can go to an affiliated optician in my town and they will mark the height in the glass and send it to the factory for correction.
Just make sure you can return the glasses free of cost if they dont have a solution.

Oh and another tip: If you by any chance now the pupillary height of your current glasses you can give the online seller the size of your glasses, pupillary heigh, PD and they might be able to use this to put in the correct height.

@Dlskidmore tried to find an online seller who customize height, without any success. For now she tries to just create her own frames instead, because it seems to be easier :sweat: DIY Frames for Precut lenses

one would think it would be possible to customize height via webcam or augmented reality :wink:

… I found one who will do this. So it seems to be an option, but you will have to inquire individually.

Names? I really want custom PH differentials.

Haven’t gotten far on that. Currently waiting on mail order nose pads, I need the ph to move up, might be able to work with that.

What do you guys think of this way to measure your PD from old glasses?

This method works on ph as well as pd, but it’s easy to measure directly if you have the frames and plano lenses.

Ph isn’t a standard measurement like pd, it is relative to a particular pair of frames and how they sit on your face.

For example Ace & Tate does this (order online and then can go to one of their real-life stores if there’s a problem).
And for only online retailers: I think it could work if you could find out the PH in your current glasses - together with measurements of the glass it seems to be possible to also work in the correct PH in a new glass, even if the measurements of the glass are somewhat different. I know that optos can find out the PH in your glasses with one of their measurement tools, so it would be totally possible to get those infos. Sometimes I feel like a detective since starting this journey…

I think the fit of the frame on the nose is too big a factor here to just compare to old glasses. Especially for those using plastic frames.

@Dlskidmore is lucky in that she needs the frames to sit higher to raise the optical center. She can add material, but removal to lower the center probably isn’t going to work.

If you want an optimal fit 100% there is no way around going in and have somebody measure it on your face and mark the position on the glass. That would be best… If that is not a possibility, then I do think that comparing it to old glass will hopefully give the technicians who cut them to fit a better estimate-at least that is what they told me. It would surely be likewise beneficial to choose a new frame that has the same or very similar dimensions as the old one in terms of size of glass, frame and that part that sits on the nose. That would, at the least, leave you with a better chance of getting well fitting glasses.

I have also had the experience that the centre is too low down in the glass and “building up” with material didn’t work for me because it tilts the glass at the same time (I would have had to build up the ear-things as well to keep them level). Though the effect that this leaves you with is less annoying when just sitting at a desk working, but when walking it gives me vertigo.

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We make prescription lenses with a sphere (SPH) up to -10.00 or +10.00

I need -14…

I’ve contacted three places so far, none of them will offer that service.

Bah… Well ear pieces are meant to be adjustable, and it’s no loss at this point if I break these frames.


@Jane @Dlskidmore @halmadavid @Kevin.L Thank you all for sharing! I’ll see how it goes when I order online :slight_smile: (I don’t even order shoes online any more–the size is always off.)

I make my own shoes to get a good fit.

Stopped making my own clothes when Chinese stuff became so cheap, but DIY offers customization only the rich can afford.

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oh no -.- i forgot they only go to 10 :frowning: