PD for reading glasses

[Jaka]

Ok here is the thing. I have heard many times that some opticians/optometrist mostly German use distance PD for reading glasses.

At first sight this is complete nonsense but when i dig deep it makes sense. Im curious about your opinion + any reference site about this topic would be great.



So lets say we have a myopic patient. Most of them are wearing glasses for years before they come to presbiopic age. When a they look at near they "create" prism base IN witch help them to converge and on the other hand their own convergence may become weaker after some time. If you make reading glasses with deducted PD it will be something unknown for them and they might have trouble adapting or might not adapt at all couse there is no prism helping them.


On the other hand we have hyperop. If they are wearing glasses for quite some time they are use to converge because of base OUT prism (when looking at near objects) so why to change that ?
If they are not used to wear glasses their convergence should be fine and therefore they are able to converge if we make base out prism.
The only time when you should use near PD (only in hyperop) is when they have insufficient convergence or they are wearing glasses at the end of their nose...


I would realy like to hear some comments about this topic since i cant find anything about it on the internet and here on the forum but I heard about it many times from my felow optometrists.

[Barry Santini]

Ok here is the thing. I have heard many times that some opticians/optometrist mostly German use distance PD for reading glasses.

At first sight this is complete nonsense but when i dig deep it makes sense. Im curious about your opinion + any reference site about this topic would be great.



So lets say we have a myopic patient. Most of them are wearing glasses for years before they come to presbiopic age. When a they look at near they "create" prism base IN witch help them to converge and on the other hand their own convergence may become weaker after some time. If you make reading glasses with deducted PD it will be something unknown for them and they might have trouble adapting or might not adapt at all couse there is no prism helping them.


On the other hand we have hyperop. If they are wearing glasses for quite some time they are use to converge because of base OUT prism (when looking at near objects) so why to change that ?
If they are not used to wear glasses their convergence should be fine and therefore they are able to converge if we make base out prism.
The only time when you should use near PD (only in hyperop) is when they have insufficient convergence or they are wearing glasses at the end of their nose...


I would realy like to hear some comments about this topic since i cant find anything about it on the internet and here on the forum but I heard about it many times from my felow optometrists.

Supports my case for a revised "Rx" format that tells a fulfiller more of what they need to know to make proper eyewear for a specific individual

B

[uncut]

I agree, Barry.

I am also in firm belief of the fact that personalization of eyewear is what creates the perfect visual experience, or the "wow" factor.

The best eyewear is made by a "one on on" relationship with a ECP.

@op, jaka:

Welcome to the forum! Add to your discussion the fact that myopic presbyopes may have started to remove their glasses to read, or are possibly increasing the vertex distance to induce "less minus".....which gives you an even more complex divergent prism to calculate. A emmetropic presbyope may have purchased OTC readers, which may have a specific centering, depending on the manufacturer, and the hyperope may have discovered magnification, by placing their distance eyeqear at the end of their schnozz.

The human eye system is adaptive.......it is reactive, in that, given the "wrong" centering, a positioning change will create comfort. The greater the error, the shorter the comfort time frame experienced, IMO.

[Robert Martellaro]

One of the reasons we should use the DPD for readers is to assure that the principal axis is intersecting the center of roation of the eye, minimizing oblique astigmatism and power error, especially with aspheric/atoric designs and/or higher powers.

WRT to induced prism, I use the DPD for myopes, and a compromise or NPD for older hyperopes, who most likely have less robust fusional reserves, and spherical lens designs. I suspect that using the DPD with a little base-in prism might be a better solution for hyperopes though, resulting in improved on and off-axis vision and visual comfort, allowing use of aspheric/atoric surface designs without compromise.

Does anyone make a free-form generated, optimized for Rx, POW, and work distance SV near only lens?

[Barry Santini]

One of the reasons we should use the DPD for readers is to assure that the principal axis is intersecting the center of roation of the eye, minimizing oblique astigmatism and power error, especially with aspheric/atoric designs and/or higher powers.

WRT to induced prism, I use the DPD for myopes, and a compromise or NPD for older hyperopes, who most likely have less robust fusional reserves, and spherical lens designs. I suspect that using the DPD with a little base-in prism might be a better solution for hyperopes though, resulting in improved on and off-axis vision and visual comfort, allowing use of aspheric/atoric surface designs without compromise.

Does anyone make a free-form generated, optimized for Rx, POW, and work distance SV near only lens?

Rodenstock used to. Now discontinued.

B

[Jaka]

One of the reasons we should use the DPD for readers is to assure that the principal axis is intersecting the center of roation of the eye, minimizing oblique astigmatism and power error, especially with aspheric/atoric designs and/or higher powers.

WRT to induced prism, I use the DPD for myopes, and a compromise or NPD for older hyperopes, who most likely have less robust fusional reserves, and spherical lens designs. I suspect that using the DPD with a little base-in prism might be a better solution for hyperopes though, resulting in improved on and off-axis vision and visual comfort, allowing use of aspheric/atoric surface designs without compromise.

Now that's the answer i was looking for. Strange i cant find any article about this on the web.


@uncut Thx. I agree with you about adaptation but i also wanna make sure that i do anything in my power for adaptation to be as easy and "painless" as possible.

[drk]

And now we find that the optimal front curve for near correction is different for distance correction!

Makes this prescribing/filling stuff more complex!

[Robert_S]

Interesting topic