The whole point of the individual i thought was to accommodate for variations in frame position. No?
The whole point of the individual i thought was to accommodate for variations in frame position. No?
Im not doubting that.Originally Posted by Robert_S
My issue was, that dead on pupil with the 3d and up lenses, which all have that 6mm drop, were causing pt's to look well above level before intermediate kicked in, and also made the reading way to low and struggled to get to it.
The individual will adjust the design to maximize performance of the lens with various frame positions, but there are still better frame positions to shoot for that provide maximum comfort and performance. Said another way, the frame should still be fit properly to have the best performing lens, but if it is not fit properly, then the individual will squeeze the most performance out of the lens that is possible.
There is no direct relationship between the distance from the fitting point and prism reference point (drop), and the corridor length and/or power rate. Short corridors can have large drops, and long corridors can have zero drop.
Good advice. I can get better results with a budget PAL that's placed in a optimally fit frame, compared to the most expensive, optimized lens in a poorly fit frame.
This is one of many reasons why online eyeglass merchants will only capture a very small percentage of the presbyopic eyeglass market.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
GRRRRRRRRRRRRRRR
yet again, zeiss lens design is wacked.
pt had a 17mm seg, they ordered a indiv 2 for him, and to read he had to put the frame into view to be able to read. since Z did the whole job there so there should be NO reason to hang most of the read off the bottom of the frame no?( re dotted lens and was perfectly on his pupil.
Id like to know how the read is positioned when its a variable corridor... I would have thought 100% would be avail not 50%
Slim,
Are you measuring the fitting point to the bottommost edge of the lens (see diagram below)?
During dispense, is the fitting cross center pupil when the client is sitting and standing?
Are your examples moderate to high myopes?
Are they advanced presbyopes?
Are the RXs from the same doctor?
Less then 1% of my PAL fittings have a height lower than 18mm. It doesn't explain why your clients are lifting their chin to see J1, but it does imply that something unusual is going on here that may be relevant to your problem.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
I measure from where the lens surface stops, not the bevel. My edger goes off of that method so its what I have always used.
lemme see if I can find this pt's info... cant remember off hand but Im sure he was a good -2.50 or so.
We should include the bevel in our lens measurements. Usually about .5mm to .75mm. Measure to the bevel apex. Use the boxing system.
Do not measure from the pupil center to directly below the pupil as discussed in the previous post. If you do (unless the frame is perfecting round with no decentration), the fitting height will be too low.
Most folks with that distance power will take their eyeglasses off for near tasks and wonder why the reading zone is so small (low and narrow) with their PALs.lemme see if I can find this pt's info... cant remember off hand but Im sure he was a good -2.50 or so.
Any other examples?
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
The lenses are designed for fitting at pupil center. If you feel that your patients will need more reading utility than the Individual 2 Balanced design can provide, I'd recommend ordering the Individual 2 Near design, instead of "fudging" the fitting height upward. I should also add that the new Individual 2 also uses a shorter corridor length with more reading utility in most prescriptions than the original Individual lens.
Well stated. The optics of the lens design are fine-tuned for the fitted position of the frame, either way, but some frame fitting geometries are still preferable to others. The optical field of view produced by the optimized lens design can still be limited by the mechanical field of view produced by the size and fit of the frame. This is analogous to getting a wider field of view through a keyhole the closer you are to it.
Consequently, a close vertex distance, a bit of face-form wrap, and at least 8 degrees of pantoscopic tilt will ensure a wide mechanical field of view as the eyes rotate to see peripheral and near objects. The optics of the Individual 2 lens design will still be corrected for whatever position you measure, but the wearer can still run out of available lens area more quickly than necessary in a poorly fitting frame.
Keep in mind that, even for a variable-corridor product like Individual 2, the wearer will not have as much near zone area available in shorter fitting heights, below 18 or 19 mm. Although the corridor length is decreased in order to keep a minimum amount of near zone inside the frame, the lens design must still provide sufficient distance and intermediate utility as well.
As the frame becomes smaller and smaller, there is no way to avoid completely the optical compromises associated with the optics of a short-corridor progressive lens, although the design of Individual 2 is adjusted to make maximum use of the available lens area for all three viewing zones as the corridor length becomes shorter. If the wearer prefers more reading vision, however, Individual 2 Near is always an option.
Best regards,
Darryl
Darryl J. Meister, ABOM
Thanks for the info Darryl. Does switching to the Individual 2N narrow the intermediate more than the regular Individual 2?
The corridor length of Individual 2 Near will be about 1 mm shorter than Individual 2 Balanced, resulting in a slightly narrower progressive corridor. For "far" mid-range viewing distances, such as a desk top monitor at 60 cm, this will narrow the field of view slightly. For "near" mid-range viewing distances, such as a lap top at 50 cm, the higher near zone may actually widen the field of view slightly, because the wearer is often using the top of the near zone and bottom of the corridor to read.
Best regards,
Darryl
Darryl J. Meister, ABOM
I found out that I'm not a Zeiss "fitter" always had problems whit them rodenstock same problem. I'm Essilor and Shamir man works every time.
if you don't have a choice. then stay whit the GT2 that lens works well.
but stay away from Individual, i believe Zeiss have hired SATAN ti Lick them
before they leave the factory. Don't know what wrong whit them but something is.
best regards
Peter
The individual has the highest wow factor but the highest rejection rate in my experience.
I agree with Robert_S, fantastic results with the Individual, and now the Individual 2 lenses. I have not had a problem with rejection though, less than a 1% non adapt rate.
Mr. Powers, I recall seing one of your threads earlier about how you (asking others how they) fit progressives. If I recall, you fit them very low. That may be the issue with fitting the Zeiss lenses you seem to have a problem with here in this thread. Might try fitting per manufacture guidlines???
Just my 2 cents to add to the discussion.
Nope did it by the book whit my RVT my personal friend was sales rep at that time
Yes, fitting ZEISS progressive lenses "low" (that is, below the recommended guidelines that all lens manufacturers currently use, which is to pupil center) will unnecessarily compromise intermediate and near zone utility by causing the wearer to have to depress his or her eyes more to reach the necessary add power.
While fitting some progressive lenses low may improve wearer satisfaction with the distance zone utility, ZEISS progressive lenses already provide a very large, clear distance zone, so fitting the lenses incorrectly in order to compensate for a poorly conceived optical design is not necessary with ZEISS lenses.
Best regards,
Darryl
Darryl J. Meister, ABOM
RVT? Would you mind clarifying the time period are you referring to in your post? ZEISS Individual has improved quite a bit over the years. For that matter, we actually use a slightly different design in North America compared to Europe, with a slightly greater emphasis on near zone utility.
Best regards,
Darryl
Darryl J. Meister, ABOM
4 years ago
Your past experiences in Europe with the original ZEISS Individual may not really be indicative of what current users of ZEISS Individual 2 should expect in North America, due to differences between the two designs. In fact, even the European version was improved in meaningful ways with the launch of Individual EyeFit about 3.5 years ago.
I would recommend trying a few pairs of the newest Individual lens in order to see whether you experience better results with your patients. Just keep in mind that the lenses are still designed to fit at pupil center. Also, if you have patients with greater near vision or mid-range demands, remember that there are additional lens design options available now.
Best regards,
Darryl
Darryl J. Meister, ABOM
Still hear the same complaints from Zeiss shops the day to day they like the GT2 but individual is a problem lens. that don't bring anything on the table that GT2 can't.
My personal opinion it that since backsurface progressive lenses came on the marker, its only technical that the new lenses are better not in real life.
i like the old shotgun story i think its try)
Sorry for my bad english .......... I'm only a Dane
Best Regards
Peter
The basic "fingerprint" of semi-finished ZEISS GT2 relies upon the same lens design platform as free-form ZEISS Individual, so I would certainly not expect any more issues with ZEISS Individual compared to semi-finished GT2. Individual would simply preserve the intended optics of GT2 for more wearers.
Although the original ZEISS Individual was not quite as successful in North America, probably because the market wasn't quite ready for it, we have actually had a great deal of success with the latest iterations of the product here.
In fact, ZEISS Individual FrameFit won the Optical Laboratory Association's Award of Excellence for Best Lens Design in 2009, which is a fairly prestigious award in the United States for spectacle lenses.
I cannot necessarily speak to the results of the Individual lens as used in Europe, but we actually have a great deal of objective evidence in support of the efficacy of Individual lenses in North America:
First, we track the return rate of progressive lens returns through our Rx laboratories. Our semi-finished lenses like ZEISS GT2 typically run at just under 1.5%. However, the last audit I ran of ZEISS Individual returns for the same period was at 0.5%, or less than half as many:
Second, we are the only optical company I am aware of that has actually had a wearer trial of our free-form lenses against standard lenses conducted by an independent university, the School of Optometry at the University of California Berkeley, with the results published in a peer-reviewed journal:
Clinical assessment of a customized free-form progressive add lens spectacle
I have heard only positive feedback from my colleagues in Europe as well.
Nevertheless, I would be happy to try to put someone from our European offices in touch with you, if you would like to discuss with them some of the issues that you've been experiencing and how those issues might be resolved.
Please feel free to message me with your contact details.
Best regards,
Darryl
Last edited by Darryl Meister; 01-08-2014 at 02:22 PM. Reason: Fixed link
Darryl J. Meister, ABOM
Not to rude, Darryl
But you always talk technical , how they work in the real life is another story.
Wenn i was younger i had a friend, that was very in to cars, he dint had i drivers license,
after many years defending "peugoet" he finally got his drivers license, sad down i one.
he changes his mind, on paper they where the best cars, but wen he started to drive them,feel them..... it felt wrong.
you comments, in this forum often reminds me of his arguments before he got the license.
Best Regards
Peter
No offense taken, Peter.
While I do frequently speak to the technical aspects of ophthalmic optics, my previous post presents independent data for how the lenses have actually performed in real life, including the results of a large-scale wearer trial, Rx return rates for thousands of lenses, and the overall market acceptance that earned it the Award of Excellence by optical laboratories.
I believe that a large set of objective data representing actual wearers is the most accurate reflection of the real performance of this (or any) lens. I have no doubt, however, that a small number of wearers may prefer other lens designs in some cases, for whatever reason. This is, after all, the main reason that we have so many different progressive lenses to choose from today.
Best regards,
Darryl
Darryl J. Meister, ABOM
"I believe that a large set of objective data representing actual wearers is the most accurate reflection of the real performance of this (or any) lens"
I Rest My case ;-)
Darryl is right, though, and the sentence you quoted is far from 'technical'.
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