EyeWorld India March 2012 Issue

March 2012 9 EW FEATURE continued on page 10 femto technology, do you think we are going to be able to objectively demonstrate a significant difference in outcomes? KPR: Let me tell you about my personal experience with Crystalens. I was doing Crystalens implantation, and suddenly I got this Z-syndrome in one patient. After about 3 months, he developed capsular contraction. He went to the U.S. for a second opinion, and that doctor said I shouldn’t have put the lens in at all. That contradictory statement put me in trouble … When I analyzed why this happened, it’s because of the small rhexis I made … the rhexis definitely played a part, and at that point I slowed down my Crystalens practice, slowed it down because I wanted a better capsulotomy. I could not make a good enough rhexis for the lens. But now that with the femtosecond laser, my confidence has returned, and I’ve started doing more Crystalens implants again and I’m so happy with the results I get with the lens. When you come to the multifocal lenses, getting the 5.5- mm rhexis bang-on correct, and getting that rhexis edge on top of the optic edge again plays an important role in clinical outcomes. GB: Dr. Reddy, this is your gut feeling, but do you think that in a large series of cases, you’re going to see more predictable refractive outcomes with the femtosecond rhexis? There’s a lot of noise in the system as far as predicting refractive outcome; even our lenses are only labeled in half-diopter increments. When we refract, our limit is about plus/minus a quarter of a diopter. So I would be somewhat doubtful that a comparative study would be able to document better refractive outcomes. Perhaps that doesn’t matter—is your intuition as a surgeon enough? KPR: I couldn’t agree more. Yes, we need to do a study, I think. CE: It’s going to be very hard to prove because, as you say, there is a lot of noise. Comparing a well- made, properly centered manual rhexis that overlaps 360-degrees of the optic with a femtosecond- created capsulorhexis—it’s going to be difficult to prove that the difference will be significant. But I think the appeal here is avoiding a rhexis that is slightly off-center, that may not be exactly round, that may contract and shift the lens slightly off-center in the long run. The assurance of being able to do that every time I think is the major appeal. GB: Yes, and, particularly with a multifocal or a lens like Crystalens, that small difference may make a difference. Prof. Chee, as a teacher, are you concerned that if you start performing femtosecond rhexis routinely, the dexterity that has taken so many years to achieve will diminish? Are we going to dumb down our skills as surgical professionals? CSP: I’m sure that will happen. It’s just like doing an extracapsular cataract extraction [ECCE] today. When I think of the lack of control in an ECCE as compared to phaco, that especially worsens when you lose practice, I shiver the night before operating on such a case that may require ECCE for one reason or another. You will definitely lose the skill of capsulorhexis without practice, and I’m sure we will lose it when we start performing femtosecond laser cataract surgery routinely. Our younger surgeons may never even learn to perform a rhexis. Coming back to your earlier points about the significant difference in outcomes, in Singapore, we have many high myopes with big eyes and well- dilating pupils. When we look at the eye without the aid of a guide, very often the challenge is knowing precisely what a measurement such as 5.5-mm is, and it’s only after the lens is in the bag that you realize that the rhexis isn’t properly sized for the optic, and you end up with a patient with a refractive surprise. So the challenge I always face is how do I know that I have the correct size rhexis, especially in cases of high myopia. These myopic patients are coming into the operating theaters earlier and earlier, because of the demands of lifestyle. Furthermore, these tend to be post-LASIK cases. With everything put together, these are very difficult cases to manage. So I would really want a rhexis that is nicely overlapping the optic just in case I have to go back and perform a lens exchange. I wouldn’t want part of the rhexis sticking to the posterior capsule. Thus, I really see that in my practice at least, with so many high myopes, precision rhexis with the femtosecond laser is a definite plus. GB: As you say, there are more economical ways to determine the rhexis size, but I think there’s no doubt that femtosecond cataract surgery will help us achieve greater precision than we have so far. Precision incisions GB: Let’s talk about incisions. Incision construction is important with regard to wound security. Have you seen in your experience so far a benefit in terms of wound security? CE: Most of the mistakes made with a blade or diamond knife in incision creation have more to do with the length rather than the width. Some surgeons tend to enter too early and have a short tunnel, which would leak more. But with the laser, that variable is gone. The laser-created incision is precise to the length, shape and width that you set it at. That’s the advantage of the femtosecond-created incision: precise, perfectly created and positioned, repeatable. GB: I guess one of the main difficulties of a long tunnel is that it can make performing a rhexis technically more difficult, but of course with a femto that’s no longer an issue. There’s been a lot said about the use of stromal LRIs for small correction. Dr. Reddy, is this just people looking for a reason to use this technology? Do you really think that LRIs whether they’re made by a blade or by a femtosecond laser will challenge toric lenses? KPR: Personally, I don’t have any experience with LRIs, and I do so many multifocal and accommodative IOLs for refractive purposes, for presbyopia. I find that at 3 months … I have to go back treat any residual powers as they are extremely sensitive to these residual powers, and when I had an excimer laser to do the job, I never looked at LRIs in the past. But now I have the femtosecond laser, it’s something that I would like to try. However, I still feel that when you have an excimer laser as a solution, I don’t think it is really necessary to use the femto laser to perform an LRI. GB: So you prefer post-cataract LASIK or PRK as a more predictable approach? What about when used with toric IOLs? Dr. Espiritu, do you think these incisions will add additional benefit? CE: Yes, definitely, it’s something we want and it’s already programmed in the software. I never had a good experience with LRIs before, which I stopped doing about 6 or 7 years ago. I just didn’t have the consistency and the predictability with the procedure. We have had very good experience with the toric IOLs, both the monofocal and the multifocal variety. But right now, especially when you use multifocal lenses, and you don’t want the patient to spend the extra bucks for toric multifocals, the arcuate incisions created by the femto really come in handy. Then you also have the option of not opening it up on the table. You can do that after the surgery at the slit lamp if you need to correct more of residual astigmatism. The advantage of the laser-created arcuate incision is its precise architecture and depth which, at least theoretically, should translate to more predictable results compared to manually created ones. GB: It’s a precise depth but LRIs are inherently unpredictable. I must say I’m personally skeptical about LRIs—unless, perhaps, for small amounts of pre-existing astigmatism. CSP: We don’t really know how these incisions behave. Wound healing is a factor as well. Say you wanted to open one of these incisions 2 weeks after surgery, I’m unsure how well these will stay open. So I’m uncertain of their efficacy. But I think all of these questions as to whether we should go use a toric lens or whether we should be doing all these corneal procedures really beg the question as to where astigmatism is best corrected—where can we achieve better visual quality, by correcting astigmatism at the lens plane or the corneal plane? GB: Theoretically it’s the