Anyone changed PD slightly for differentials?

Has anyone slightly changed their PD for their differentials? I’m curious about this, as I have slight discomfort at near distance and wonder if this is worth a try. The biggest potential problems would probably be that looking into the distance would create prism/distortion of the type that I don’t need, and I wouldn’t be able to reuse the glasses as normalized later on.

Opticians apparently debate things like this among themselves, and there are multiple schools of thought, with arguments for and against both ways.

I’m just thinking, I have an intensive, full-day electronically administered exam in my future, and am trying to get the glasses sorted out well beforehand to minimize fatigue and maximize performance.

At -2.50 SPH, and close working distances, 1mm could conceivably make a difference to both near (good) and distance (bad effect) vision and comfort. All compromise and no free lunch.

Also, @Johnn, any thoughts/experience on this, or anything from Antonia Orfield?

@jakey, any personal experience?

Disclaimer: everyone is different and there is no one size fits all; you have to try things. But I’m doing my homework first.

If anyone thinks this is a bad idea, please say why.

One nice thing about needing no correction for computer work - no issues with PD. :slightly_smiling_face:

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@Ursa, I think it’s going to take 2 diopters of progress before I feel right doing that all the time…under -2.

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I have been doing that for many years with -3, but very close to the screen. Now that my right eye is at -1.5 , I can work comfortably at a screen distance of between 65 and 70, giving me a range of blur challenge, and no challenge if my eyes get tired. This is on the strength of my right eye only. The left may catch up in a few years’ time. :anguished:

Yes, I do it for short periods without glasses, but it never feels quite right even though the vision is fine if I’m close enough. Neither do any differentials I’ve ever tried, either, including some prescribed by an eye doctor long before EM existed, unfortunately. My slightly weak normalized feel best, but I know it’s not good to use them for long durations for computer and writing. Trying to sort that out now and find something that will work. Hopefully the slight power bump and possible PD narrowing do the trick on the next pair. I should probably just get two pairs and try both, one with the modified PD. But there is still a slight uncertainty about the exact power, as well…I might need a 0.50 increase as I seem to like my differentials on the stronger side now that I’ve gone through the blur adaptation reversal process…but I am not buying 4 pairs at once if I can help it. I think I need a test lens kit. Too bad I no longer have access.

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Two thoughts. Could you get someone to help you measure pd at near (while looking at the object dx)?

Are you in the US? I have two test lens kits and looking to dump at least one.

My ODs over the last ~40 years have bounced my PD between 62 and 60 mm. Antonia toggled my distance Rx from 62 to 60 mm. She didn’t offer any particular rationale. That was her response to my complaining about a feeling of “unreality-despite-clarity” I felt from most all glasses for decades.

When I started Endmyopia a year ago I ordered two pairs to the same spec except for the PD – one at 60 and one a 62. After wearing both under every circumstance for a couple months I didn’t see any difference between them. Since then I have ordered all my Zennies at 61 mm and had no trouble.



Agreed. Mine ranges from 59 to 61, including a dual pd of 30, 30.5.

I’m just passing thru while my AL shortens up. The discomfort is temporary.

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Thanks for the feedback. I may have to just get two pairs, with 1mm difference, and see which works better. I was professionally measured at 64.5 in the past for distance. I basically order all of my glasses as 64 up to this point. I tried 65 once, but it didn’t feel quite right. At near, I feel like I’m fighting the current differentials…they’re too weak, and the distance PD might not be helping.

Guidance is usually 2mm less for near pd

Please remember to post your findings when you have tried both pairs. I’m sure other people will benefit from your experience

My current differentials will eventually be used as my normalized when my eyes improve to that point. Just a cost savings measure for me so I don’t have to purchase another pair. So I have not changed my PD. I use the far PD for all glasses. It probably makes it a little off but if just using for the computer I have had no major issues.