# Optical Forums > Progressive Lens Discussion Forum >  The truth about Camber

## ThatOneGuy

Does anyone remember when progressive lenses used to be sold on the merits of their design? "This lens will give you wider intermediate," "That lens provides you with the most add power," "The other lens wont work with a seg over 17," etc.

Does anyone remember when a new lens hit the market, it would be availble in one or two lens materials only? Other materials and photochromics and polarized versions would come out "eventually."

The promise of freeform lenses was that we would have better correction for unwanted astigmatism and all materials available on all lens designs immediately. Period. That was the promise.

The more complex the design gets on the front surface OF A FRONT SIDE MOLDED PRODUCT, the more limitations you have in product availability and advancement. Also, the SIGNIFICANTLY higher overhead costs to labs who must stock the various complex options available.

Can someone explain to me why camber lenses are being presented as a huge step FORWARD? I fail to see based on any information presented that camber is any improvement over, say, a Hoya lens, or the physio 360. No one lens design works best for everyone, and yet the camber lens seems to present a one size fits all lens via its elephant trunk molded lens. At least the Individual 2 adjusts corridor lengths based on many perameters, and Autograph offers multiple fixed corridor lengths.

So said another way, I guess I'm asking if anyone can explain how camber isn't just a front molded progressive with backside optimization.

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## Tallboy

Because it is a plano blank not one with a molded add.  It is different because of this.  Any number of progressive designs could be cut on the backside in theory.  The blank would have a different base curve for the DV rx and the NV RX, all on the same plano blank.  In theory optimizing this - especially for hyperopes.  I've had meh results though others (such as Craig on here) have said they have great results.  I think it comes down to what designs are being used - I probably used the wrong labs who chose poor designs (cheaper?)

I haven't been won over by it for the same reasons of higher overhead / lack of extra "wow" results.  However labs would only have to stock "camber blanks" in base curves not base curves AND adds.  But yeah.

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## ml43

All other front side molded PAL's besides the Camber have areas of converging and diverging curves(front to rear relative).

The Camber is converging across the entire surface, and is horizontally spherical.

It's not a front side molded PAL, it's just a special aspheric lens, that was designed to help optimize free form PAL optics.

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## Craig

It is our lens of choice.  We only offer the Camber and use another if we have no choice but the compensation and zones are our favorite.  
Best Lens Made and only one the is actually an improved design of the blank!

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## hyperoptic

Camber is a step forward because it helps address many of the concerns found in single vision frontside Digital PAL's, it allows for flatter curves in plus powers, better thickness profiles, and wider fields of view.  By combining the two surfaces (the front is a continuously variable surface not a PAL) together patients experienced easier adaptation, better near visual performance, and overall better comfort (these were the results of our wearer trial)  Advantages for the ECPs are availability and flexibility, the designs can be decentered, its available in materials from CR-1.67 polarized, Trans, and clear.  The principals behind it are not new, they are based in science that is well accepted in practice, we just applied the Tscherning ellipse to a digital platform.  Camber lens technology can be used with 4 different lens designs each developed for lifestyle selection in mind, with corridors in one MM steps with a minimum fitting height of 14.  If you'd like more information give me a call and I will send you some more information and answer all your questions.  Kurt Gardner 336.529.9284 (Im with IOT)

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## Robert Martellaro

> Can someone explain to me why camber lenses are being presented as a huge step FORWARD?


Flatter moderate plus lenses with a full backside PAL surface for hyperopic absolute presbyopes without a positive ocular curve or the use of high refractive index low Abbe lens materials.

No royalty fees to Zeiss. 




> Camber is a step forward because it helps address many of the concerns found in single vision frontside Digital PAL's, it allows for flatter curves in plus powers, better thickness profiles, and wider fields of view.  By combining the two surfaces (the front is a continuously variable surface not a PAL) together patients experienced easier adaptation, better near visual performance, and overall better comfort (these were the results of our wearer trial)  Advantages for the ECPs are availability and flexibility, the designs can be decentered, its available in materials from CR-1.67 polarized, Trans, and clear.  The principals behind it are not new, they are based in science that is well accepted in practice, we just applied the Tscherning ellipse to a digital platform.  Camber lens technology can be used with 4 different lens designs each developed for lifestyle selection in mind, with corridors in one MM steps with a minimum fitting height of 14.  If you'd like more information give me a call and I will send you some more information and answer all your questions.  Kurt Gardner 336.529.9284 (Im with IOT)


Hello Kurt. I have a few questions.

Is Camber optimized for position of wear with full Rx optimization over the entire lens? 

If true, is there design optimization (zone configuration, periphery design, corridor length, etc.)

Is there an Rx tweak at the distance and near reference points? If so, I would expect to see a compensated Rx.

What are the maximum plus powers (max distance plus near) for Trivix and 1.60?

Best regards,

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## hyperoptic

> Is Camber optimized for position of wear with full Rx optimization over the entire lens? 
> 
> If true, is there design optimization (zone configuration, periphery design, corridor length, etc.)
> 
> Is there an Rx tweak at the distance and near reference points? If so, I would expect to see a compensated Rx.
> 
> What are the maximum plus powers (max distance plus near) for Trivix and 1.60?
> 
> Best regards,


Camber is a compensated lens using Digital Ray Path Technology (www.digitalray-path.com) we are maximizing the fields of view along the entire surface of the lens using default or provided POW measurements, we take the personalization further by allowing the selection of a design that can be matched to a persons lifestyle, (Larger distance, balanced, larger reading zone, and a softer design for first time PAL wearers)  This will mean that you will get a compensated Distance Rx and add power.

Maximum powers can vary slightly and we are always trying to make a lens more efficient, I would contact your Camber lens provider (if you dont have one visit camberlens.com for a list) and they can let you know their power restrictions.

Thanks

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## Robert Martellaro

> Camber is a compensated lens using Digital Ray Path Technology (www.digitalray-path.com) we are maximizing the fields of view along the entire surface of the lens using default or provided POW measurements, we take the personalization further by allowing the selection of a design that can be matched to a persons lifestyle, (Larger distance, balanced, larger reading zone, and a softer design for first time PAL wearers)  This will mean that you will get a compensated Distance Rx and add power.


Thank you. 

I see that the inset is calculated for work distance as well as IPD, vertex distance, and Rx. I would expect to see that from a FBS PAL; there's no reason not to implement that calculation unless it's a low end design. After all, some of the premium semi-finished lenses have some degree of inset and corridor length optimization for base curve and add power.

A couple more questions if I may. 

If we map a plano sphere +2.50 add PAL, and a +1.50 -3.00 x 45 PAL, many PAL design cylinder plots take on a significantly deformed appearance. Does the  Digital Ray-Path® technology modify the PAL optics so that the intended PAL design is reasonably true  across a very wide range of RXs and fitting parameters? If so, is it calculated in real-time? 

WRT the distance, balanced, and near designs, could you describe the tradeoffs made when going from one design to another, specifically the distance and near zone widths and their associated corridor lengths.  




> Maximum powers can vary slightly and we are always trying to make a lens more efficient, I would contact your Camber lens provider (if you dont have one visit camberlens.com for a list) and they can let you know their power restrictions.


I'll do that (Walman is my primary lab). I understand that it's hard to pin this down unless we know a little about the frame shape, size,and decentration, primarily with plus powers.

Best regards,

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## hyperoptic

> Thank you. 
> 
> I see that the inset is calculated for work distance as well as IPD, vertex distance, and Rx. I would expect to see that from a FBS PAL; there's no reason not to implement that calculation unless it's a low end design. After all, some of the premium semi-finished lenses have some degree of inset and corridor length optimization for base curve and add power.
> 
> A couple more questions if I may. 
> 
> If we map a plano sphere +2.50 add PAL, and a +1.50 -3.00 x 45 PAL, many PAL design cylinder plots take on a significantly deformed appearance. Does the  Digital Ray-Path® technology modify the PAL optics so that the intended PAL design is reasonably true  across a very wide range of RXs and fitting parameters? If so, is it calculated in real-time? 
> 
> WRT the distance, balanced, and near designs, could you describe the tradeoffs made when going from one design to another, specifically the distance and near zone widths and their associated corridor lengths.  
> ...


It has been our experience that not as many modern designs to actually vary the inset, or if they are now it is a recent development, the same goes for design decentration.  

The maps we typically see are the Plano with a 2 or 2.50 add when we make the Rx more complex the power map changes, that will happen with a compensated or non compensated lens because the lens is now taking into consideration a more complex Eye Lens system, so using a power map they will look different but the way the patient perceives light would be consistent.  I hope that made sense...All Camber (and IOT for that matter) designs are calculated in realtime at the local lab, even something like changing the frame or Seg can cause slight changes in the calculation (usually .010 or less but still a change) 

I am happy to describe the difference between the designs, essentially we have designs that put focus on different focal lengths, the Distance focused design will be clear above the 180 line, but that forces the remaining unwanted astigmatism down and creates a slightly smaller reading zone, the near focused PAL does the same but in reverse.  Its important to note that a person wearing the distance will still be able to comfortably read a book, or computer, or whatever else, and the near focused wearer can still safely function out doors.  What having these choices allow the ECP is the ability to fine tune the wearer experience so that for the patient who says "I wish I had just a little more reading" can have it, and vice versa for the distance wearer.  

If by width you are referring to the width of the intermediate, this is one of the ideas that is more marketing than science, look at the Minkwitz Theorem, essentially the width is proportional to the length, the longer the corridor the wider the intermediate will be.

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## Robert Martellaro

> It has been our experience that not as many modern designs to actually vary the inset, or if they are now it is a recent development, the same goes for design decentration.


Not many, but as stated, the premium designs are more capable. Ovation from the late 90's modified the corridor length by base curve, so not so much of a recent development. No doubt, we usually get what we pay for.




> The maps we typically see are the Plano with a 2 or 2.50 add when we make the Rx more complex the power map changes, that will happen with a compensated or non compensated lens because the lens is now taking into consideration a more complex Eye Lens system, so using a power map they will look different but the way the patient perceives light would be consistent.  I hope that made sense...All Camber (and IOT for that matter) designs are calculated in realtime at the local lab, even something like changing the frame or Seg can cause slight changes in the calculation (usually .010 or less but still a change)


See the image below. It's from http://www.opticampus.com/files/prog...presbyopia.pdf 

My question is, if the intended design is the first image, and a complex Rx is introduced, do I get a map that's closer to the second image, or closer to the third image?




> I am happy to describe the difference between the designs, essentially we have designs that put focus on different focal lengths, the Distance focused design will be clear above the 180 line, but that forces the remaining unwanted astigmatism down and creates a slightly smaller reading zone, the near focused PAL does the same but in reverse.


Thank you, that's what I was looking for, the redistribution of the unwanted astigmatism.




> Its important to note that a person wearing the distance will still be able to comfortably read a book, or computer, or whatever else, and the near focused wearer can still safely function out doors.  What having these choices allow the ECP is the ability to fine tune the wearer experience so that for the patient who says "I wish I had just a little more reading" can have it, and vice versa for the distance wearer.


Right. However, if I order a balanced design for example, a myope will need a shorter corridor than a hyperope, especially with the higher dioptric powers. Do we manually reduce the corridor length, or does the software make any contribution? 




> If by width you are referring to the width of the intermediate, this is one of the ideas that is more marketing than science, look at the Minkwitz Theorem, essentially the width is proportional to the length, the longer the corridor the wider the intermediate will be.


No, as stated, the distance and near zone widths, but specifically the distance zone. IMO, from personal wearing tests and several manufacturer's trials, a good PAL design should first and foremost have a generous distance zone, with options for a higher near zone without upsetting to any significant degree the distance functionality.

Thank you for taking the time and effort to answer my questions. I can't promise I'll try your lens, being a moderate myope, but emmetropes through high plus with strong adds should take a strong look at what Camber brings to the table, another tool in our toolbox of solutions.

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## rdcoach5

I'm wearing the camber. It's better for near but is it worth the cost? I can't justify the increase.

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## ThatOneGuy

> I'm wearing the camber. It's better for near but is it worth the cost? I can't justify the increase.


worth the cost compared to what?

I'll respond to the other posts when I have more time...sorry been crazy busy...thank you everyone for the replies thus far.

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## Robert Martellaro

> I'm wearing the camber. It's better for near but is it worth the cost? I can't justify the increase.


Better how? Compared to what? What is the Rx? Include additional details if you have time. Thanks.

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## Sphinxsmith

We've been using Camber lenses from Identity in IL and have been very happy with them. In fact they are appreciably less expensive than the conventional lens we had been using. 
They've been extremely versatile and I'm not having to hop around from lens to lens and lab to lab to get just the right product. 

cs

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## rdcoach5

> worth the cost compared to what?
> 
> I'll respond to the other posts when I have more time...sorry been crazy busy...thank you everyone for the replies thus far.



My Rx -9.50 +1.00 x 115  +2.75 add  
                   -9.25 + 1.25 x155
 Previous wore Ind 2 and  another IOT design and GT2 3D

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## Jason H

Dunno, I've had as many hits as misses with camber. It makes so much more sense from a surfacing standpoint for hyperopes instead of myopes. Interesting stuff, but better? Physics has laws instead of guidelines for a reason.

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## Robert Martellaro

> My Rx -9.50 +1.00 x 115  +2.75 add  
>                    -9.25 + 1.25 x155
>  Previous wore Ind 2 and  another IOT design and GT2 3D


Thanks rdcoach5. We've both been around long enough to know that there's no single design that's optimal for all RXs and individuals.




> Dunno, I've had as many hits as misses with camber. It makes so much more sense from a surfacing standpoint for hyperopes instead of myopes.


Yup. Working the steepest curve makes the most sense, and that's why a spherical front with the progressive optics on the back works better with minus, but hard to do with plus (expensive to work both surfaces). Camber looks like a nice in-between work around, that is, only a moderate increase in cost, due to the proprietary blanks, without significant optical compromises compared to surfacing the progressive optics on the front of the lens.

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## Sphinxsmith

This was a nice breakdown on the tech.
http://www.2020mag.com/ce/TTViewTest...essonId=111613

cs

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## Robert Martellaro

> This was a nice breakdown on the tech.
> http://www.2020mag.com/ce/TTViewTest...essonId=111613
> 
> cs


Anyone else having a problem with the statement that non-camber FBS PAL designers use up their design tools to correct optical problems created by a single vision front surface?

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## Jason H

Again, minus curves ought to be on the concave surface.

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## Jason H

And a -5.00 with a +2.00 add is still minus all the way around

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## Craig

> Anyone else having a problem with the statement that non-camber FBS PAL designers use up their design tools to correct optical problems created by a single vision front surface?


He is speaking of prioritizing the design and it makes sense to me.  I learned that the diopter drop is 2 from the distance and actually 1 above the MSRP; did not know that.

We use this lens 100% if we can and all wear it as well.

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## ThatOneGuy

> Anyone else having a problem with the statement that non-camber FBS PAL designers use up their design tools to correct optical problems created by a single vision front surface?


Yes. It is grossly apparent that the person writing the article has never been involved in 3D modeling or calculations. There is no such thing as "using up" design tools.

I'll write more later.

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## optical24/7

I glanced over the above 20/20 article. What I didn't see was how the Camber lens addresses the vertical cyl induced outside the umbilic by increasing the BC from top to bottom. Maybe Kurt could tell us here.

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## Robert Martellaro

It's vertically oriented, something that Essilor showed to be less upsetting to the wearer than an oblique orientation. 

I hope they don't have to use up all of their design tools compensating for the more complex aspheric surface though. :Smile:

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## optical24/7

> I hope they don't have to use up all of their design tools compensating for the more complex aspheric surface though.


Now that's funny!


I'll be putting the Camber through my own blind vetting process with my persnickety engineer patient base with next year's "Exploratory Budget".

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## ml43

> Yes. It is grossly apparent that the person writing the article has never been involved in 3D modeling or calculations. There is no such thing as "using up" design tools.
> 
> I'll write more later.


depends on what you define as a "design tool"

if we are talking about zernike coefficients to optimize a conic, after about the 10th term, things get a little messy, especially from a manufacturing/metrology stand point.

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## MakeOptics

"Using up the design tools", aspherics and deformed conicoids have their limits; if you are using these back side methods to cleanup the front surface created issues then the back surface becomes far to complex to compensate for additional errors.  By moving the progression to the front and making it continuous across the front surface, the design can focus on the actual patient parameters on the back.  Also the marginal astigmatism created by a PAL design isn't all about the diopter value, sometimes it is more dis-jarring to look through a lens that has less marginal astigmatism but is oriented obliquely than a design that has more marginal astigmatism but is oriented vertically, horizontally, or aligned with the patient prescription.  This true distortion can cause floors to seem warped or shapes to look funny.

The Camber and the old Omnifocal have a lot of similarities, the Omnifocal went away because of the cost/complexity in production, that no longer exists so the Camber lens is a vintage design that may have been greater than the Varilux design which replaced it in the 60's, every design after looked more like the Varilux design, now we are actually seeing an older yet possibly better lens design reemerging.  Time will tell if the design is better, just the fact that many are talking about it means that the lens is obviously a contender in the marketplace.

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## Uncle Fester

> This was a nice breakdown on the tech.
> http://www.2020mag.com/ce/TTViewTest...essonId=111613
> 
> cs





> *DISCUSSION: WEARER TEST*
> 
>  IOT, in association with the University of Madrid, designed and  conducted a double-blind wearer trial comparing a Camber finished lens  with one processed from a single vision blank. Both used the same  contemporary IOT back-surface progressive design technology. Both  prescriptions were made from the same material, same central base curve,  in the same frame, and worn for one week each. The only difference  between the two pairs of eyewear was the lens blanks they were processed  from: Camber versus single vision. Wearers and testers were unaware of  which lens was which. After trying them both, wearers were then asked to  compare lenses.
>  When asked, "Which lens do you prefer the most?" wearers preferred  Camber 2 to 1. Regarding ease of adaptation, 8 of 10 reported that  adaptation to Camber seemed easier. Nine of 10 reported better near  vision. Considering all factors, 55 percent (a majority) found Camber  better, 39 percent found it to be equal.
>  Wearer trials like this are not very common today because it is very  tough to show significant differences in wearing experiences. Test  subjects find it difficult to differentiate and express their  preferences. Additionally, the trials are very expensive and  time-consuming to perform. Therefore, these reported results are  significant.


 I'd like to see the powers of the 6% who did not feel the lens was better or as good.

Did they randomly vary or were they specific to higher plus/minus or cylinder powers?

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## Robert Martellaro

> I'd like to see the powers of the 6% who did not feel the lens was better or as good.


People are strange.

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## ThatOneGuy

> It's vertically oriented, something that Essilor showed to be less upsetting to the wearer than an oblique orientation.


I always saw their claims about that as disinformation to try and combat Zeiss' horizontal symmetry patent from the 80s.

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## ThatOneGuy

> "Using up the design tools", aspherics and deformed conicoids have their limits; if you are using these back side methods to cleanup the front surface created issues then the back surface becomes far to complex to compensate for additional errors.  By moving the progression to the front and making it continuous across the front surface, the design can focus on the actual patient parameters on the back.


Far to complex? I'm wondering if you can restate this in a way I can understand. The design isn't being customized with a tool...these are 3d math operations and tooling instructions that of course have their limits, but those limits exist regardless of base curve. 

Has the progression been moved to the front with camber? I argue yes. Others seem to be trying to argue no, while saying yes in their explanations.

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## ThatOneGuy

> I'd like to see the powers of the 6% who did not feel the lens was better or as good.
> 
> Did they randomly vary or were they specific to higher plus/minus or cylinder powers?


My interpretation of the wearer test was that they were comparing IOT vs IOT. The limitations are in their math, and I would be curious to see how those same 6% feel about Hoya vs Seiko vs Shamir vs Zeiss designs.

Additionally, I wonder how long the patients wore each product.

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## Robert Martellaro

> I always saw their claims about that as disinformation to try and combat Zeiss' horizontal symmetry patent from the 80s.


Horizontal symmetry is related to how the unwanted astigmatism is distributed from the nasal to the temporal portions of the lens, with a symmetric distribution providing the best binocular balance.

Essilor's contribution was to show that the orientation of the initial bands of astigmatism on either side of the umbillic played a factor in wearer comfort, with a vertical orientation being the most comfortable. 

http://www.icarelabs.com/wp-content/...LVAR200836.pdf

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## lensgrinder

> Far to complex? I'm wondering if you can restate this in a way I can understand. The design isn't being customized with a tool...these are 3d math operations and tooling instructions that of course have their limits, but those limits exist regardless of base curve.


If you were to take a cone and cut it in half with the cut being parallel to the base you would have a circle, cut it at an angle to the base you have an ellipse.  These, along with the parabola and hyperbola, are conic sections.  They are plane curves.  If you were to rotate these curves around the axes of symmetry you create the conicoids.

When you use an aspheric lens you are using a form of conicoid knows as an ellipsoid(flatter than a circle) and there are different types of ellipsoids.
We use these types of curves to reduce aberrations associated with off-axis viewing(i.e. looking into the add of a progressive).  

There is a limit to what these surfaces can do.   




> Has the progression been moved to the front with camber? I argue yes. Others seem to be trying to argue no, while saying yes in their explanations.


A progressive decreases the radii of curvature as the rotates downward, so in that sense it is a progressive.  The progressive optics, Pow, etc still have to be ground on the back surface.  I would say it is not a front surface progressive in the traditional sense.

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## ml43

> Far to complex? I'm wondering if you can restate this in a way I can understand. The design isn't being customized with a tool...these are 3d math operations and tooling instructions that of course have their limits, but those limits exist regardless of base curve. 
> 
> Has the progression been moved to the front with camber? I argue yes. Others seem to be trying to argue no, while saying yes in their explanations.


If we assume that the front and rear surfaces can be made perfectly(which they can't), then splitting the "3d math operations" between the front and rear surfaces, reduces the amount of corrections you need. 
Normally in the form of Zernike polynomials, or some other type of higher order polynomial and/or exponential.


This is the primary argument that was/is used against digitally generated back side PAL's versus traditionally ground PAL's.
Because they both have a surface that is spherical, they will still display aberrations caused by the spherical surface.
If you can mold a front PAL surface and conventionally grind the rear spherical surface to the same accuracy and design as a digitally generated back side PAL, 
then from a design/metrology standpoint, they are equal in terms of performance/amount of aberration.  


The camber has a base curve variation on the front(horizontally spherical across the entire front surface), not a focusing power variation like molded PAL's(not spherical across any axis below the PRP).

If you had a SF molded PAL, such as a GT2 or a physio.  You could use it as is, and it would perform like a plano distance, with an add equal to the molded add, and still have a usable corridor.

A SF Camber blank will not focus light, the whole lens will be blurry, and it does not have a corridor.

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## sharpstick777

In short, the variation of front curve full add traditional progressive lens goes like this:

Distance > Convex
L Soft Focus Area, or Junk:
    >Steeper Convex
    >Very Steep Concave
    >Moderate Convex
Reading > Steep Convex
R Soft Focus Area
   >Moderate Convex
   >Very Steep Concave
   >Steeper Convex

Back to Distance > Convex

Note: Mix of vary steep concave and convex curves.

Compare that to the Camber:

Distance  > Convex
Soft focus or Junk  >  Steeper Convex
Reading  >  Steep Convex
Soft focus or Junk  > Steeper Convex
Back to Distance > Convex

note: All Convex

A traditional design goes back and forth, effectively sending any focal point over a very wide area in multiple directions, which by definition is distortion. 

The Camber by contrast will keep that focal point in a smaller range, because the front lacks the horrible mix of Concave and Convex Curves present on traditional lenses.  These curves exist in theory on the Camber, but well off the surface of the lens and way from a patient field of view.  Its simply a magnification of the tiny entry zone of a front add progressive, say a 5 mm circle, and using and expanding that for the entire front of the lens.

I had the exact same idea about 12 years ago, and should have patented it then.










> Does anyone remember when progressive lenses used to be sold on the merits of their design? "This lens will give you wider intermediate," "That lens provides you with the most add power," "The other lens wont work with a seg over 17," etc.
> 
> Does anyone remember when a new lens hit the market, it would be availble in one or two lens materials only? Other materials and photochromics and polarized versions would come out "eventually."
> 
> The promise of freeform lenses was that we would have better correction for unwanted astigmatism and all materials available on all lens designs immediately. Period. That was the promise.
> 
> The more complex the design gets on the front surface OF A FRONT SIDE MOLDED PRODUCT, the more limitations you have in product availability and advancement. Also, the SIGNIFICANTLY higher overhead costs to labs who must stock the various complex options available.
> 
> Can someone explain to me why camber lenses are being presented as a huge step FORWARD? I fail to see based on any information presented that camber is any improvement over, say, a Hoya lens, or the physio 360. No one lens design works best for everyone, and yet the camber lens seems to present a one size fits all lens via its elephant trunk molded lens. At least the Individual 2 adjusts corridor lengths based on many perameters, and Autograph offers multiple fixed corridor lengths.
> ...

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