I have a confession...

[Barry Santini]

Well, after all the discussion here, and both Bill W. & TLG's comments, I decided to order a current set of POW-optimized progressives (brand will NOT be disclosed) with my recorded and found pantoscopic tilt of -3 degrees.

Guess what?

HA!

The lab called to clarify the "-3" number, and when I verified it, they said that number "could not be entered".

So I defaulted to "0" again.

Interestingly, in this case, the recorded negative panto (retro?) was somewhat compounded by the client's habitual, slightly head-back posture.

So, I ask: How much does/should posture enter into the compentations for POW optimization here?

I'm not sure. I need the help of all Optiboarder's.

Barry

[obxeyeguy]

Interestingly, in this case, the recorded negative panto (retro?) was somewhat compounded by the client's habitual, slightly head-back posture.

So, I ask: How much does/should posture enter into the compentations for POW optimization here?

Barry

I am far from your level on this Barry, but sounds to me like you should blow some smoke in front of a mirror when dispensing these.

If the actual panto is -3, and they can't enter it, and it's accurate based on patients head posture, what't the point?

So it's a Point of wear, based on what we feel is a point of wear, not you, the fitter.:hammer:

Back at you.:cheers:

[Laurie]

Hey Barry,

Fun being a pioneer, eh?

It is my understanding that only the fitting height should be taken in regard to head positioning.

Pantoscopic Tilt should be measured with the eyes/head positioned straight ahead.

I cannot imagine anyone wearing a frame with negative panto (or retro), and still be able to see through the bottom of the lenses.

?

: )

Laurie

[Barry Santini]

Laurie:

I dont know much about a Pioneer, but I do think you are as close to correct as I can see:

Determine Pantiscopic tilt with the client's head "plane" in the "orthodox" position.

Yet, if this revealed a pantoscopic tilt of say, 3 degrees, *and* they habitually tilted their head forward, increasing the "as worn" pantoscopic tilt to say, 9 degrees, what should one do?

Alternately, I'm wondering just what the actuall difference is between the orthodox-determined tilt, and the factoring of head posture on the effect of the same.

Seems to smack of similarity to the thread on Prism ground vs. prism by decentration. In that prism case, it was determined to be no different.
What about in the case of posture induced panto vs. the found panto in a headplane/orthodox position?

Lot's of theory. I need help, here Optiboarders...

drk, Harry C., Darryl M., Robert M, etc., want to chime in?

Barry

[Uilleann]

According to most standard logic and optical ray tracing when compared against normal natural human eye placement and movement patterns, both pantoscopic tint and positive face form should always give the best vision. When the lenses are further optimized using digital lens processing and taking into account vertex as well, this *should* be the pinnacle of optical progress in custom eyewear available today.

But there's always those very very few patients who despite all we've been taught over the years, and indeed all we "know" to be true....will go against all logic and reason, and will prefer the opposite of what *should* work.

Barry, you are certainly in the very top percentile of dispensers in taking such detailed and accurate measurements - every time. It's alarming to me how many times I've heard fellow opticians and even speakers in C.E. classes decry the usefulness of such measurements. I do believe as many here have already stated, that you are well ahead of the curve, and that your standard will likely become the ultimate standard of care in dispensing in the next decade or so.

At least we can hope...

Best!

Brian~

:cheers::cheers::cheers:


Edited to add:

P.S. I'm gonna put my neck out on the block for this one, but isn't panto completely irrespective of neck/back posture? The frame and lenses are held at the same angle relative to the cornea regardless of head/neck/back positioning, assuming a given frame adjustment and lens placement correct? The OC may change relative to the geometry of the frame perhaps, but even then I'm not seeing how that would relate to panto and face form and the like. Chop away! hehe

[Laurie]

Hey Barry,

To reiterate what you mentioned in regard to the web seminar with Eddy D,

Pantoscopic Angle: Relationship to the frame front and the temple angle

Pantoscopic Tilt: Relationship to the patients cheeks and temple tilt, when in a straight ahead gaze.

An upward tilt of the head will affect the fitting height, but will not affect the relationship to the tilt towards the cheeks. I'm with others, in that I would not dispense eyewear with negative panto/retro... with retro in relation to the cheeks, the patient will look below the frame, not using the lenses at all!

Either they need to choose a better frame, or I need to improve the adjustment.

And, it goes without saying (I think) that the proper amount of pantoscopic tilt should be in place prior to taking this measurement.

...and the beat goes on...

: )

[Barry Santini]

Thnaks for your help, Laurie.

For those of you measuring panto now, can you *really* eyeball the difference between 5 degrees and 8 degrees?

Following, do you agree that the above is a small range, arguably what orthodox panto should lie within (this is the default range for most designs).

If you agree, then if we're willing to accept a 3-4 degree range as being "within" what the lens deisgner intended/expected...

And...if true orthodoxy with pantoscopic tilt is *always* referenced to the exam room, i.e., Zero (0) pantoscopic tilt..

Then why would that same, measly 3 degrees now, when "minus", mean the difference between "seeing" and "not seeing" out of the bottom of the frame/lens?

I want to have a debate/discussion about what pantoscopic tilt threshold value should not be crossed, and why.

Curious....

Barry

[Barry Santini]

I just rec'd a reply from a major, high-quality, POW optimized, FF lensmaker, who will accept a pantoscopic value range from -5 to 20 degrees!

So...if the normal range is between zero and, say 10 degrees, what do you say about the orthodoxy of fitting a frame with a 20 degree pantoscopic tilt?

Yeah, I gettin' lost. But I'm in for the count...

Barry

[Barry Santini]

What say you about Harry C.'s stated preference for *reverse* face form?

He says: "That's the way I like it!"
("I wear my glasses with negative faceform, but my lenses have negative decentration as well. I wear a -4.75 and I like thin edges, so when I pick a frame out I go for a little negative decentration and negative tilt to compensate. It's amazing how often I hear my glasses are wrong or out of adjustment, but they're right on to me. )

Who here wants to argue with Harry C. over this...

Reverse face form, to me, seems more at odds with conventional/optimal ophthalmic lens fitting and theory than 3-4 degrees of measely retroscopic tilt.

Discussion...

Barry

[Barry Santini]

What's Visually Better:

1. 8 degrees of pantoscopic tilt with NO proper attention or adjustment in vertical placement of the "OCs" on spherical-base, corrective curve lenses.

Or....

2. Zero pantoscopic tilt, and the "OC" of the same lenses placed smack dab in front of the pupil

and...

in either of the above, say the Rx is -4.75, high index on the proper curve, and in the case of #1, the client suffers reduced acuity straight ahead...

or

In the case of #2, the client encounters wild prism, tilt, chromatic aberration and olblique astigmatism when looking down in the lenses.

??????

Barry

[Robert Martellaro]

So, I ask: How much does/should posture enter into the compentations for POW optimization here?

Barry,

Posture will affect where one looks through the lens, but I wouldn't think it would influence the tilt on the straight ahead gaze. We can check that by marking the lens at the pupil center on the primary gaze, and then marking the lens with the head tilted back (or down for retro) so that the lens is perpendicular to the floor- the difference, times two, should be the tilt.

And...

Probably #1 for most folks at that power. #2 if there is significant (more than 1 D) anisometropia.

[jpways]

So the problem as I reading it is you can't order it with the proper amount of retro, how about the proper amount of vertex distance?

As best as I can picture this (though I'm not that good with the theoretical part of the field, so there may be a feasibility issue I'm missing) you order the job with 0 tilt and the desired vertex distance, once you add the retro you should still have the proper distance correction. In the case of a multifocal, you'll probably need to decrease the add due to the effective power gain with having the reading further away, but I'd be more concerned with proper distance correction than optimal reading correction.

To explain the picture in my mind so someone can tell me if this is possible or not. I'm picturing the center of the distance at a constant distance away from the front of the eye, regardless of the amount of pantoscoptic tilt. So that you can reposition the lens from a neutral tilt to a retroscoptic tilt, without otherwise effecting the distance optics.

[Barry Santini]

And he clarified pantoscopic tilt and POW compensation:

1. Panto tilt is determined just as Laurie stated - with the client's head/facial plane in an upright/orthodox position.
2. One needs to keep in mind that noticeable postural anomlies should be allowed to be factored in to the determination.
3. POW compensations would generally not be made if the chosen base curve and OC position is in compliance with corrected curve theory for the chosen index.
4. But- today, we prefer flatter, thinner aspheric lenses, so this departure from CC orthodoxy requires compensation. Also, if the design pole of the lense is not intersecting the eye's CR, you need compensation.
5. Sometimes the ff, pow software will provide an apparent compensatory reading for focimeter verification.

That's a wrap for me...

Barry

[DC Optix]

What are y'all using to measure panto? I've seen a simple little dial type gauge that Zeiss had out a few years ago, but are there other tools?

[HarryChiling]

................

[Robert Martellaro]

I just rec'd a reply from a major, high-quality, POW optimized, FF lensmaker, who will accept a pantoscopic value range from -5 to 20 degrees!

Barry,

I found this at Rodenstock's Candian site. This was from the Impression Hyperop.

http://www.rodenstock.ca/rodenstock/...ct%20Sheet.pdf

Individual parameters:
PD: 15 to 40 mm
CVD: 7 to 50 mm
FFA: –10° to +15°
PT: –10° to +20 °

So...if the normal range is between zero and, say 10 degrees

I would think normal would be eight to twelve, and is probably the default value if the panto tilt is not given.

...what do you say about the orthodoxy of fitting a frame with a 20 degree pantoscopic tilt?

I had one like this recently where I needed to get the bottom of the frame from being right in the middle of the page when reading. A deeper frame was called for but my hands were tied (POF).

[sharpstick777]

Wow!

I just found these cool blue calipers that measure the width of someone's head! What I can do is code all the frames on the boards to match the calipers and let the patients do their own frame selects. That way they can take thier own blame for going home with crappy looking eyewear.

Amazing.

[Robert Martellaro]

Wow!

I just found these cool blue calipers that measure the width of someone's head! What I can do is code all the frames on the boards to match the calipers and let the patients do their own frame selects. That way they can take thier own blame for going home with crappy looking eyewear.

Amazing.

I've heard that Lenscrafters, back in the US Shoe days, used similar devices and methods for choosing the frame size. Not sure what this has to do with using free-form technology and the appropriate software to optimize lenses with negative or extreme tilt values.

[eyemechs]

I'm 13 years out, but this forum is a treasure trove. I'm facing quite a similar problem with a px's postural idiosyncrasies.

Has the optics/ophthalmic realm changed it's tenor since B Santini's post?

And he clarified pantoscopic tilt and POW compensation:

1. Panto tilt is determined just as Laurie stated - with the client's head/facial plane in an upright/orthodox position.
2. One needs to keep in mind that noticeable postural anomlies should be allowed to be factored in to the determination.
3. POW compensations would generally not be made if the chosen base curve and OC position is in compliance with corrected curve theory for the chosen index.
4. But- today, we prefer flatter, thinner aspheric lenses, so this departure from CC orthodoxy requires compensation. Also, if the design pole of the lense is not intersecting the eye's CR, you need compensation.
5. Sometimes the ff, pow software will provide an apparent compensatory reading for focimeter verification.

That's a wrap for me...

Barry

[drk]

This is a great thread. Barry at his best.

[Prentice Pro 9000]

When I'm taking POW measurements for either personalized or wrap SV and progressive lenses...

And I find I'm reading a NEGATIVE Pantoscopic tilt (away from the cheeks and toward the brows)...

I find myself LOATHED to write the same down on my lens order form. I usually reduce the value to "0" (zero).

Why is that?

I'm especially loathed to write down a value such as I obtained for sunwear today...

-10 degrees pantoscopic tilt.

Anyone share my (secret) aversion to writing down negative pantoscopic tilt?

Discussion, please.

Barry

I never knew you could enter in a negative value for Panto. In most cases, wouldn't you just adjust it out?

Also, this makes me think back to the few occasions(maybe twice) that somebody claimed they were more comfortable with a crazy amount of retro-tilt. I wonder what was up with that.

[Robert_S]

Some optical software allow for negative panto now. I think that's due to it becoming more common nowadays

[Robert Martellaro]