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Video interview with Dr. Florian Sutter: 

IbexTSdoubleflex SMLWell, I basically developed it for myself. I was not completely happy with the IOLs available in the market. So, I started to learn about IOL manufacturing and finally decided to have an IOL produced according to my own specific ideas.


I think we need to look at the basics first. It is a hydrophobic IOL. I prefer the hydrophobic material over the hydrophilic because of it’s clarity and surface quality. Hydrophilic IOLs are lathe cut. The original material is hard and the curvature of the optic is shaped by a computer guided tool. Therefore, the surface is not perfectly smooth but somewhat irregular. Some IOLs actually show ringlike micro-structures on their surface as a result of this cutting process. In order to smooth these irregularities, the IOLs are so called “tumble polished”: simplified they are put in a bottle full of glass dust and then the bottle is “tumbled” for several hours or days. This smooths the surface irregularities, but also make the surface somewhat “dull”. Also the exact optical power is subject to uncertain an uncontrollable effects during the tumble polishing process.

Hydrophobic IOLs, on the other hand, are cast molded. The molds are stainless steel high precision tools and the optics do not have to be polished or “improved” in any way. Therefore the optic quality of hydrophobic IOLs is superior.

By the way, not all IOL manufacturers are able to control the cast molding process. Some apply the lathe cutting and tumble polishing technology also to hydrophobic IOLs by freezing the material for the cutting process… So one really has to look deep into the manufacturing process to select the optimal IOLs…


Hydrophobic material is also stiffer than hydrophilic material, so the IOLs sit more stable in the eye, once they are implanted successfully. The incidence of PCO is lower and there are less often scratch marks and damages to the surface of the IOL due to the implantation process.


In my eyes, the only downside of hydrophobic IOLs, really, is the more challenging implantation process. We basically want small incisions for a cataract procedure and the same size hydrophobic IOL requires a larger incision than a hydrophilic model. Or when we look at it from the other perspective: the only advantage of hydrophilic IOLs – in my opinion – is that they are dead easy to implant through small incisions.


B3As I said I want my IOLs to be the optimal solution once they are inside the eye. I do not mind if the implantation process is challenging. This problem can be solved and the correct implantation process can be learned.

So the next factor of the optimal IOL is the size. I am convinced that IOLs should be as large as possible for a specific eye.


First, I want the IOL to re-establish the iris-lens-diaphragm as good as possible. It should stretch out the capsular bag nicely, but not too much. We do not want the periphery of the IOL to interfere with the ciliary ring.

Second, we want 100% overlap between the rhexis and the optic of the IOL. Of course this can be achieved in a small IOL as well by tailoring the rhexis small, but then capsular phimosis may be a problem. Therefore, I like to make a large rhexis and was looking for a large IOL. Also, I believe that IOLs should come in different sizes for myopic, emmetropic or hyperopic eyes, because the size of the anterior segments and the capsular bags vary depending on the axial length and the white-to-white measurements.


The doubleflex IOL comes in 3 sizes and the M size for diopters between 17.00 and 22.50 is 7.0mm in optic diameter and 13.35mm total diameter.


B4The reason who almost all IOLs out there are 6mm in optic diameter is again the implantation process. Surgeons want small, astigmatism-neutral, watertight incisions. The industry offers phaco handpieces and phaco needles that enable the removal of the lens through incisions of 1.6mm or even smaller. There are especially small hydrophilic IOLs that can be implanted through this type of incisions, but I my opinion they do not meet the criteria of an IOL that I want to implant into the eyes of my patients. I think an incision of 2.2 or 2.3mm is optimal. These incisions are de facto astigmatism neutral; phacoemulsification is very efficient and a high quality IOL can be implanted.


This is where the Ergoject Injector by Medicel comes into play. Before I started to develop the Doubleflex IOL I had a cooperation with Medicel to develop this very special single handed screw injector. This injector has an unusually large loading chamber and a very efficient and controlled advancing mechanism for the IOL. In the process I realized that with this injector a significantly larger IOL can be implanted through 2.2 or 2.3mm.


If you look at the haptics of the IOL you realize that they are very large and very slim. I would call them “elegant”, but that was not the goal of the design, rather the result. We wanted the haptics to stretch out the capsular bag in an optimal way in order to avoid the so called “stress folds” on the posterior capsule. This is why we designed them very large and also the total diameter is larger than usual. But at the same time they need to be flexible to snuggle nicely into the periphery of the bag and to allow some degree of capsular bag contraction. It is important not to overstretch the bag. Overstretching the bag leads to lose zonules, because the volume inside the bag is reduced compared to the preop situation. This interferes with stable refractive outcomes. In extreme situations, the equator of the overly stretched bag can tilt behind or in front of the ciliary ring.


For the same reason there are the two notches in the haptics. We call them “designated flex points” because the haptics will flex at these to points when being implanted into the bag. My team is convinced that this design will contribute to exact and stable refractive outcomes of the doubleflex IOL. At these flex points, the remaining material is very thin. During the design process we were worried that the haptics may break here during the implantation. But this is absolutely not the case. At the first flexpoint closer to the “shoulder” of the haptic, the minimal width of the haptic is just a little bit larger than the thickness of the material. This flexpoint is a little bit stiffer than the second one and allows for the general adaptation to the overall size of the capsular bag. At the second flexpoint, the minimal width of the haptic is even smaller than the thickness. This flexpoint allows the haptic to snuggle perfectly into the capsular bag. During possible capsular bag contraction, both flex points will be able to adjust, but more flexibility is granted at the second point. As the material at this point is narrower than thick, and flexing will take place exactly in the plane of the IOL. We are convinced that this contributes to the refractive outcome. If a haptic without this design is flexed over it’s flexibility, the result will be a deviation out of the plane, leading to a refractive change due to the IOL being pushed forward or backward or being tilted.


B7Looking at the optic, the doubleflex is a standard IOL. The optic is monofocal and aspherical neutral. We plan to offer a toric version soon and maybe an multifocal one. But this is not the focus. I believe this IOL is of specific value in the myopic and highly myopic range. We currently have diopters from zero to thirty in half diopters, above thirty can be produced if ordered and we are evaluating to even offer IOLs in the negative diopter range soon. The myopic range is where I believe the Doubleflex IOL has a the largest benefits over a “normal» IOL with an optic diameter of 7.25mm and a total diameter of 14mm.


B8We would really like to label the doubleflex for sulcus implantation. For this, however, a prospective trial is need and such a trial is difficult to plan since a sulcus implantation is only done in the rate event of a complication. But we may look into that.


For a sulcus implantation, the total diameter is not the only factor to look at. We also need to consider the thickness of the haptics in the sulcus. That’s why generally single-piece IOLs are not recommended for sulcus implantation. Phyiol once had a single piece IOL on the market that was labeled for sulcus implantation and there are some add-on IOLs with that label, so it seems to be possible. I think in the myopic range, there may be enough space, but in the hyperopic range one has to look into that very carefully. But I am definitively not encouraging that. For the time being, the label is for in the bag implantation only.


B9Our IOL is “minimally yellow” or “naturally yellow”. In my opinion there is no evidence for the macular protective effect of the blue light blocking IOLs. On the other hand some of my patients complain that their subjective color perception is very “cold” after the implantation of a completely clear IOL. Minimally yellow gives you a somewhat “warmer” color perception. This is the reason for the blue light filter in our IOL. But if patients are worried about the macula, they may feel reassured by having the potential effect.


No, I totally agree. In general, patients do not notice, even if one eye has a clear IOL and the other eye a yellow IOL. But a small minority of my patients mention in the early phase after surgery, that the light and the colors are “like in an ice skating hall”… Later that complaint is not a problem any more. I only remember some artists like painters or photographers mentioning that change in color perception for a longer period. With a minimally yellow IOL that problem disappears in my experience. But I agree: these are individual cases that do not show up in a larger study. The yellow tint of the doubleflex is also really minimal. One needs to hold two IOLs next to each other under the microscope to see which one is yellow and which one is not.


B11Yes. As you see there are two numbers on the box indicating the optical power. One is the “nominal” optical power, but of course there is always some variability in the manufacturing process. We therefore measure the true power of every IOL individually and print his on the box as well. Of course, we are aware that this small deviation from the average is not important in most cases, but in some patients the biometry lies between two half diopter steps. In these cases, it is a “nice-to-have” feature.