OSN Technology and Equipment Workshop presentation: Tecnis Multifocal IOL

Y. Ralph Chu

The following excerpt is from a presentation by Ralph Chu, MD, at the 2009 OSN Technology and Equipment Workshop on the Tecnis Multifocal IOL.

Y. Ralph Chu, MD: When I first submitted the talk, we were going to talk about the diffractive lens, so I will actually share our experience with the Tecnis Multifocal IOL. And then I will share a couple of other technologies that I was asked to speak on that I have experience with. I am a consultant to AMO. I will be speaking about the Whitestar Signature phaco system and the Tecnis 1-Piece lens (Abbott Medical Optics).

We are one of the clinical investigative sites for the Tecnis Multifocal. I think we all know the benefits of the aspheric surface, but I think it's important to understand that not all aspheric surface lenses are created equal. We know that the patent on the Tecnis lens gives us the largest amount of aspheric correction, -0.27, while the IQ (Alcon) lens gives a -0.7, so there is a residual spherical error. And then you can see if you don't correct spherical error, you still get some blur around the letters. I think the quality of vision is different.

That's one of the myths, that all aspheric diffractive lenses are the same. I don't think that's true, and we have experience with all of the available lenses.

The study parameters are standard FDA clinical trial protocol. Eighty-eight percent of the subjects are 20/20 or better distance-corrected, and what this shows is that you don't lose a lot of distance-corrected. One of the drawbacks of a diffractive multifocal lens is loss of distance clarity. So, you might see that slightly, especially with the diffractive/refractive design. I think you see that less with this full posterior surface diffractive lens. That's one of the design differences between, say, the ReSTOR Aspheric (Alcon) and the Tecnis Multifocal.

With distance-corrected vision at near, 94% were 20/30 or better. This is the best reading lens out there. We use Crystalens HD (Bausch & Lomb). We've had experience with the multifocal IOLs. In terms of getting good near acuity, this is the best reading lens available, especially for the multifocal lens.

When you look at simultaneous vision, 93% 20/25 or better at distance and 20/30 or better up close. And one of the key things to note in the FDA clinical trial results is no astigmatism correction. We were not allowed to enhance residual astigmatism. And some of these patients were supposed to have 1 D or less, but then it was up to 1.25 D. And we all know that getting under 0.75 residual astigmatism is important.

It is a diffractive multifocal lens. So, you are going to have a slight drop-off in intermediate. But one of the other myths out there is: Is this going to be the same drop-off that I have had, say, with my ReSTOR aspheric patients? Our experience is different. There is more intermediate range with the Tecnis Multifocal. And I think it's a design difference. When you look at that central zone, that little clear zone in the middle, the Tecnis Multifocal has a larger clear zone centrally. It's about 1 mm versus the 0.7 mm of the ReSTOR design. And this is not being critical of either lens. I think there is a place possibly for each. But, really, you get more depth of focus through that 1 mm clear central zone of the Tecnis Multifocal, better intermediate vision. To me, that's the second myth.

So, 84% of patients report never wearing glasses. I never liked this statistic, because it really doesn't necessarily apply to your clinical day practice. Essentially, these patients are very happy with their up-close. There are a few that will need some intermediate reading glasses. And anecdotally, we didn't get a significant complaint of visual symptoms at night. So, one of the possibilities is, with a full diffractive posterior surface, you can get more glare and halo.

When you look at the package inserts from the ReSTOR and the Crystalens, the Tecnis Multifocal FDA clinical data actually reports less glare and halo than even the Crystalens, which was actually very positive and sort of surprising. But really, there was not significant reports of night vision problems long-term. So you are not going to see a big bump-up with this lens compared to, say, the ReSTOR aspheric.

In the laboratory, we know that the full diffractive posterior surface gives us pupil independence. One of the complaints that we had with the diffractive/refractive design was in a dimly lit room; when the pupil dilated, the reading vision went down. But you do not see that, and you should not see that, with the Tecnis Multifocal. So, people will be able to read in many different lighting conditions.

When you compare the aspheric ReSTOR to the Tecnis Multifocal, in a smaller pupil size there is not a huge difference between the two lenses. When you get to larger pupil sizes, for sure there is a significant difference in quality of vision. That, again, is the first myth, which is, not all quality of vision, not all aspheric multifocals, are the same.

Our experience has been excellent with the Tecnis Multifocal lens. I think in our practice now, there will be two tracks to get a presbyopia-correcting IOL. There will be an accommodating IOL track and there will be the multifocal track, which is the Tecnis Multifocal. And we'll probably see a larger percentage of patients getting a combination of Tecnis and Crystalens to give them spectacle independence. We hope that plays out as the Tecnis becomes available on the market.

The other technologies that we have experience with are also Advanced Medical Optics products, but these are things that we use. I like to talk about things that we do use.

I just bought a surgery center this last year, and one of the reasons we chose to outfit it with a Whitestar Signature was the combination of a Venturi-peristaltic pump. It's the only system out there that has the combination pump. I think all three systems have represented significant forward advances. I think they are all much better than their previous generations. I think you could do well with either one, but I like the combination of Venturi and peristaltic.

As anterior segment surgeons, we like the peristaltic because of the safety. But the weakness of the peristaltic really is cortical cleanup and a vitrectomy. And so having the combination gives you that flexibility. Up until now, even with, say, the Infiniti (Alcon) and the Stellaris (Bausch & Lomb), you can choose one or the other. The Stellaris has the combination, but you can't do it on the fly; you actually have to set it up as a Venturi and then set it up as a peristaltic. This one is all-in-one pump, all-in-one system within the same case. You can switch between the two on the fly in a serial fashion. This is similar to the other systems out there where the new pumps give you higher vacuum, better flow rates, more control. But the dual pump is unique to the Signature, the Whitestar.

It's a true combination pump. What I do is, I set my nuclear removal on peristaltic; I set my cortical removal and viscoelastic cleanup on Venturi. And if there is a vitrectomy that's needed, you can actually have that Venturi programmed in. The retinal surgeons love Venturi. It gives you more control when you are removing the vitreous, and we found that to be true with this. It's also an electrical-driven Venturi. So, you don't need to have a big can of nitrogen sitting in your OR, and it's electric. You just plug this cassette in, and the cassette switches back and forth on the fly.

The combination is something to actually take a look at and see if that would fit into your way of doing cataracts. With the new presbyopic IOLs, I found that was important. I think cortical cleanup is actually more important, for a good result, than actually even removing the nuclei. It's the harder part of the surgery. More vitreous is lost during cortical cleanup than nuclear fragmentation. Getting good cortical cleanup is important to minimize PCO, which we all know affects multifocal quality outcomes as well as accommodating IOL outcomes, and actually preventing IOP spikes. If you do a lot of co-management, or even if you didn't, again it helps improve your outcomes, minimizing any hassles - not really significant complications, but hassles.

It's really the fluidics that have advanced. This chamber stability is critical within the system. The new software represents a significant advance. I think you really have to try it in your hands to believe this, but you can actually see this when you try the machine. The fluidics are improved. The combination of the Venturi and peristaltic is critical. We have a setting on our Signature that is actually a floppy iris setting that's unbelievable. We have a low flow, high vacuum and incredibly stable chambers. It really turns basically potentially disastrous cases into a routine case.

Our monofocal IOL of choice has really switched from a Tecnis three-piece lens to the Tecnis 1-Piece lens. I really love the three-piece lenses. I like the stability that they have. I like the fact that if there are capsular problems during surgery you can put the three-piece lens into the sulcus. But I find that my technicians and myself love the one-piece acrylic lens design. And the reason we switched was, we were one of the investigational sites for this new platform and found that the quality of the vision was incredible. So, this is the first lens that we actually had the "wow" factor with a monofocal lens. When I agreed to do the study, I was just like, "Sure, we'll put the monofocal lens in. It's no problem." It was a monocular lens trial, so we had regular monofocals in one eye and the study lens in the other eye. And patients actually came to us and said, "I like the lens in my study eye," which I would not have expected from a multifocal platform.

And as we did more investigation into it, I think a lot of things came into play. It wasn't just this haptic design. It wasn't the 360 posterior edge that protects against lens cell migration that you see here that minimizes PCO. We actually found that the acrylic material is better than the other available acrylic materials out there. The manufacturing process minimizes glistenings. And you actually have something called the Abbe number, which optical scientists understand as chromatic aberration. So, this material has the least amount of chromatic aberration, which actually helps improve quality of vision. We know that spherical aberration reduction helps improve quality of vision. You couple that with chromatic aberration reduction and you actually get this augmented effect. And I think that's why our patients are saying, "Wow!" This monofocal lens, the same refraction between the eyes, is 20/20 vision. They like this lens better than other monofocals that we're using at the time.

So, you have the design aspects. You have the lens offset from the plane of the haptic, so it gets good capsular bag contact, which helps minimize PCO. We also learned from the Crystalens that getting close to that nodal point helps quality of vision. So, I think this lens has some things that the other single-piece lenses out there that are one-piece acrylics don't. They are very similar, but we like the Tecnis. Again, that quality of vision, that "wow" factor with the chromatic aberration being decreased, as well as the spherical aberration, I think matters.

We did a little post-approval trial. With 123 subjects, at 1 year postop, 91.5% were 20/40 or better uncorrected at distance, which is actually excellent statistics for a multicenter trial. So, that was pretty impressive. That's what we were seeing in the clinic when these patients came in. They were very, very happy, with their visual results. At 1 year postop, 100% were 20/40 or better best corrected distance. You would expect that in a study where you had to choose patients with healthy maculas.

So, excellent visual quality with the Tecnis 1-Piece. The same ease of insertion that you have with the Alcon AcrySof lens. But really, I think the material is different and there are differences in this line that help improve the quality of vision. So, that's why we chose this lens as our monofocal lens of choice at this stage.

Thanks very much.

The OSN Technology and Equipment Workshop is a showcase of the clinical benefits of new surgical and diagnostic equipment, surgical instruments, software, vision testing and contrast sensitivity testing systems. Step beyond the brochures, bring the products in the exhibit hall to life, and hear surgeons' clinical impressions of the newest equipment and instrumentation. This workshop will allow attendees to interact with surgeon users and manufacturers.