Exact same reaction from a co-worker. Similar RX, with more cyl. She is in love...she's also a very skeptical person, a real hard sell to every new product.
Exact same reaction from a co-worker. Similar RX, with more cyl. She is in love...she's also a very skeptical person, a real hard sell to every new product.
11
Originally Posted by Verunica
I am pretty sure like most digital lenses this is surfaced using a single vision blank. That would explain the clarity you saw on the unsurfaced uncut he showed you....
I do not believe it is a single vision lens. From all the information Essilor provided to us, it utilizes dual optix technology, meaning they are utilizing both sides of the blank.
I ordered a second pair of S-4D yesterday in a different frame (slightly shorter B) and bumped the add a quarter for the extra small stuff on the phone that's getting harder and harder to see these days. :) Not expecting much difference of course, but will see if the 'redesign' of the new frame measures and add translate into any discernible visual difference between pair A and B here.
It is not dual *surfaced*. It's a cast front/digital back design. As stated earlier, you can't have Transitions on a dual surfaced design. (fronts surfaced also.)
Right.
Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA
“As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein
Very well described.
So which progressive is NOT offered in transitions on account of true front and back cnc milling?
The original Hoya iD, and the present day 1.74 index of refraction Zeiss Individual (PAL & SV?), in the higher powers.
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.
Thank you Robert, that is very informative, I didnt know that. The lens reps seem to imply that the front surfaces are milled as well and I guess it makes sense that if the product is available in Transitions (which is a front surface-applied coating I think) than it cannot be front-surfaced. I notice that a "sun sensor" treatment is available where transitions isnt (Hoya My Id lifestyle) isn't= I guess this is an in-the-mass treatment? Great to learn new things, thanks.
I probably missed a few, but your most welcome. There are advantages, economically and performance-wise, to placing the progressive optics on the front (better for some Rxs), or on the back. In either case, 99% of the time it will be the back surface that is worked on a free-form manufacturing platform, with results that will vary greatly by the complexity and quality of the software and manufacturing know-how, and not by where the progressive optics are placed.
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 agree with this 100% Robert. My rule of thumb is that I won't use total back side PAL designs when the patient is hyperopic or doesn't have enough minus Rx to overcome the add power. ( In these cases you are creating a bi-convex reading area)
Anyone else getting back some odd compensated rx's with the S4d? Anyone having great success with this lens? So far I have dispensed around a dozen and have only had one "Wow", a few "Meh's" and the rest not enjoying them as much. The latest compensated RX I have received from the lab today is ;
RX ordered +1.00 -0.25 x 96 +2.00 Add
PL -0.25 x 117 +2.00 Add
Compensated RX from the lab
+1.02 - 0.23 x97 +1.05 Add
-0.07 -0.22 x 118 +1.23 Add
I know they take into consideration vertex, panto and all of those measurements, but with that little RX could it change the add that much (almost cut in half?) If someone can give me more information on how they calculate the compensation RX and what might change the add this much it would be greatly appreciated. So far the only answers I can get from Essilor is that is what the computer spits out. Do we just trust these compensations? Thanks for your time and replies.
burke110,
I cannot come up with a reason for that kind of compensation on the add power with that low of a prescription. Do you have the vertex/faceform/panto that you sent in to have the 4Ds produced?
Ultimately it is up to you if you are willing to trust the compensations without having a better understanding of why it is doing this. For me, the answer is no.
It seems that the only way to keep the back concave on these high plus backside PALs is to use a really steep base curve, not very desirable cosmetically (or optically), considering it's probably a premium product.
One possibility is that there are only two add powers, I'm guessing a +.75, and a +1.75, with the rest on the back. That way they only have to produce 16 semifinished blank configurations (two adds and eight or so base curves).
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 thought about that too. Essilor has always put the total add in the compensated add, and don't normally split.
Only in the higher plus powers, about +6-7 total by my math. Its why Zeiss chooses that number to move some of the add to the front as the back gets flatter. Using Minkwitz, you reach a point of diminshing returns as plus powers increase. Backside Add works better in most cases to reduce TPD. The key factor is that a front side add creates a concave curve against a convex lens, which sky rockets distortion. Only until the ability to compensate on the back reaches that distortion point will a front side add make sense.
I just got my first pair of Varilux S lenses mounted, so this is my initial report. I have to admit, this is the most unusual lens I have ever worn. It’s both brilliant and confusing, and it has the remote possibly of being even dangerous.
Initial impressions are awesome. When I put the lens on it was the first progressive that did completely feel like single vision. There are very low geometric distortions and the “soft focus” areas have been moved very far away from the foveal cone to appear almost invisible when looking through the center. The corridors seem very wide and looking around the room, the entire lens seems mostly usable. If I didn’t give the lens a deeper look I would be convinced it’s the best lens made.
But…
The first issue that when I turned my head, the lens feels like it has negative face form. I don’t know if you remember CRT tube TVs as we went Flat Screen. If you went back and forth between the 2 technologies everything seems bent. The Varilux S bends everything just a little bit like an old CRT screen does. Although in most lenses in my low RX = (-1.25 -.50 x80 /-1.00 -.50 x81/ +1.50) I actually see better without Point of Wear measurements, this is the first lens that is much better with them. I would not order this lens without the vertex and face-form measurements in any RX. It feels like my BC is off by 2D. The S Fit reduces this to 1D, but doesn’t eliminate it entirely. It still feels weird.
As a result, it’s the first progressive I have ever worn that ever gave me a headache, and I had to take off after less than 2 hours. The second day I could only wear it for 6 hours before I got uncomfortable and fatigued. I have never once had to remove a progressive lens before.
The second issue is the reading zone. Although it feels huge at first when not focusing on anything small, when I go to the fine print it’s only perfectly clear in the very center. Reading a pill bottle clearly required bringing the object very close and low in the lens. The zone left to right of the reading was OK for a long distance, but there was a slight fuzziness that caused my eyes to tire quickly. If you’re not focused on text it looks completely clear for a very long way, but when you get down to the fine print I could read much better without my glasses on. The effective reading zone was very low in the corridor; I had to tilt my head up farther to get it than any other progressive I have ever worn.
The intermediate is wide, and more usable for text. The declination angle of the intermediate definitely favors a laptop/tablet/cel over a PC. On a PC Monitor it was slightly fuzzy although wide, and I would find eyestrain sooner. Strangely, reading through the intermediate was clearer than the reading zone. Over all text looks slightly strange, there is a very slight glow on one side that makes it look like chromatic aberrations or contrast is too high or my monitor is dying.
Distance Vision: But here is the real deal killer for this lens in my RX, the S lens induces a large amount of unwanted vertical cylinder/prism in the top portion of the lens, and it increases toward the peripheral. It’s enough that at night it’s almost like the old ghosting you get with VHF television antennas. As a result Freeway signs were only readable at about 140 feet away at night, 180 in day. With my Seiko lenses, I can make out small freeway lettering clearly at 240 feet. My DVA/OU with the Varilux S is 20/20 -1, with the Seiko’s I am 20/15 -2, the loss of a almost full line. That’s a substantial difference. I drive about 40K -50K miles a years so for me that extra 100 feet of usable clarity is important. That’s a large loss in potential reaction time of about 1.2 seconds.
The biggest problem with this is the potential to push the cyl only a tiny amount my DVA would drop dramatically, I am right on the edge. What if some of these lenses come off the line with a tiny bit more of unwanted cyl? This lens could very easily become unsafe simply because of normal power variations in a few extreme cases. We are right at the edge of what most people could tolerate, dropping DVA to 20/30 quickly.
I think that Essilor is on to something significant with the S lens series. In many uses and walking around it functions beautifully. It really is a lens that feels like SV with little perceptible distortion or geometric distortions. Text and fine detail is another matter. Heavy readers, computer users, and people who drive a lot with definitely notice the slight degradation that occurs in almost all zones, but especially the loss in reading freeway signs. The goal of the S is to keep the foveal cone clear, counter-balance spacial distortion so its less noticeable, and push out the crud so it can be cut off. In most things it’s successful, but for me I cannot consider this a truly great lens since it reduces both my distance and near VA so substantially.
Some guesses on the Technology (Essilor is being very tight lipped, so I could be completely wacked). The front uses a reverse aspheric design that varies across differing axis to balance parallax deviations in the lower zones. The transitional curves are incredibly soft enabling large areas to appear more clear. Where most progressives can be delineated as a 4 zone lens, this is really an 8 zone lens. The gentler delinations allow for an appearance of reduced total distortion. In realty TDP is spread all over the lens a little, resulting in it looking better than it really is. The power at 90 to the umbilic through the corridor bends down and out, not up and in like most progressives. The result is that the distorted transitional zones are moved farther way from central fields of view, the downside is that the peripheral reading starts to become the intermediate zone quickly, reducing effective reading area. It also allows that transitional zone between reading and distance to be longer, and softer, creating a perception of usefulness. It also reduces unwanted prism and cyl in the near zone. Combined they create the perception of less distortion to the wearer. Anytime we can move distortion out we can at some point cut more of it off.
Fitting tips: This lens will work best for general purpose non-demanding wearers who don’t depend on the sharpest vision near or distance. It will also work best on type B personalities. This lens will not work well for engineers, perfectionists, lawyers, type A people, photographers or those who use the computer, read or drive more than 2 hours a day; there are better lenses for those people for a lot less money. You will gain an advantage offering the S Fit to EVERY patient over the S Design using the Panto, Face-form and Vertex. It’s ungainly without them. I would be very hesitant to fit the lens on a patient who has base curve sensitivities. If a rock star pops into your practice though, it would be a perfect choice as long as someone else is driving the tour bus.
Because of the acuity issues in mine, I would verify your patients DVA before you allowed them to leave your practice with the . There is a chance acuity could be low enough in some rare cases/powers to make driving unsafe.
This is very close to being a great lens, and it’s by far the first decent Essilor Free-form lens. Frankly, after so many mediocre Essilor lenses lately I was hoping for more. I am hopeful that Essilor will improve the VA far and near, most lenses undergo improvements after launch even if their never announced. Until then, I cannot recommend this lens yet because I put a greater weight on patient safety than I do comfort, and comfort is everything the S is about. It’s strangely a progressive lens for people who don’t really need a progressive lens. It has great potential, but with the loss in clarity in multiple zones it steps away from being the best in everything except reducing spacial or geometric distortions. There it still excels.
I posted my review here, i had a big MEH as well. Pls let me know if my experience parralells yours at all.
When we put an add on the front, the Progressive transitional curve moves through from the front distance curve, which is convex, to the transtional curve, which is steep concave, back to the add, which is again, steep convex. So we go >Convex (dist)> Steep Concave > Steep Convex (reading) > Steep Concave > Convex (distance). Back and forth.
In a backside add lens, it runs: Steep concave (distance) > Moderate Concave (transitional) > Flat Concave (reading) > Moderat Concave > Steep Concave. Inherantly, the curves diverge less in a backside add power reducing Total Potential Distortion about about 40% in reality. All Concave to varying degrees. This is the curve at 90 deg to the umbilic. We cant optomize the umbilic as effectively so their is still some inherant distortion.
The add power location has an enormous affect on distortion. Its why most FF lenses have the add on the back.
In higher plus powers the gap narrows, so we get a decreasing rate of return as the back gets too flat to compensate effectively.
I'm pretty sure that's related to corrected curve theory, not the Minkwitz theorem.
There's a grievous flaw in the design, fit, or the manufacturing. My guess is the latter since this has not been reported elsewhere.
Distance and near? That's a pretty small market!Fitting tips: This lens will work best for general purpose non-demanding wearers who don’t depend on the sharpest vision near or distance.
I'm not sure that I follow you. I would agree that a high plus, high add backside PAL can have a S shaped geometry on the back surface, unless the base curve is very steep.
From what I've read, the CW seems to be only slight optical advantages with the backside placement of the progressive optics; i.e. 10% increase in field of vision, slight reduction in skew distortion. Probably insignificant from the wearer's perspective. There are disadvantges. The only significant advantage is reduced cost due to reduced inventory requirements.The add power location has an enormous affect on distortion. Its why most FF lenses have the add on the back.
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.
My office is a big Varilux office and we have the machine for the 4D S lens.
Am I understanding this right- there is very low level distortion over the whole lens? And that this allows the lens to have clearer periphery vision but slightly less clear straight ahead vision?
The issue I see is in the Nanoptix Technology. Nanoptix is like taking a bunch of paper toilet rolls and putting them together side by side to create a honeycomb structure, except with nanoptix this is done on a microscopic level and this mesh is filled in with different refractive materials, with the walls of each tube/pixel having a coating that absorbs visible light. If you were to take a tube and tilt it slightly while looking down the middle you will start to notice that you see more of tube walls. The advantage is they have discretized the optics of a lens surface to be comprised of multiple cells that theoretically are optimized for their position. This means that each point can have a consistent merit function applied across the surface of the lens (distortion in this case). The problem is that these cell walls/tubes introduce a known defect, they cause diffraction which scatters light and the absorption of the walls also means reduced transmittance. They reduce this effect by making the walls super thin and by making the mesh work thin as well but I still believe that the lens experiences some loss of contrast and clarity as an expense of reduced distortion.
I would share the patents but I made a promise.
http://appft1.uspto.gov/netacgi/nph-...ux+AND+essilorFor add power prescriptions below +3.00D, the invention typically keeps the unwanted astigmatism to a maximum of approximately 1.00D or less. For certain high add power prescriptions such as +3.00D, +3.25D, and +3.50D, the invention typically keeps the unwanted astigmatism to a maximum of approximately 1.50D.
I assume that this is the only way to significantly reduce unwanted astigmatism and swim, a low add PAL combined with electro-active elements. The "Varilux S" probably has low levels of astigmatism, but can it be less than 1.50 DC on a +2.00 add PAL?
Where's the beef?
Last edited by Robert Martellaro; 11-04-2012 at 11:51 AM.
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.
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