EyeWorld India March 2012 Issue

March 2012 11 EW FEATURE continued on page 12 is most important for us, we don’t really need to go that deep into fragmentation—you can easily manage the phaco part with a standard chop. GB: As I understand it, part of the problem leading to nuclear prolapse is the creation of a seal around the rhexis edge, which might have led to a build up of pressure during hydrodissection. Is that one of the rationales for not using hydrodissection? CE: Yes. When we were undergoing training, that was one of the first things they warned us about. They explained that the air bubbles were still there posteriorly, so when you added fluid, the air bubbles and fluid together would push the nucleus up, producing a capsular block syndrome that could lead to rupture of the posterior capsule. We were advised to release the bubbles from beneath the nucleus first by splitting it—usually with the phaco tip and a second instrument—and only then could you go ahead and hydrodissect. This, however, involved having to come out with your phaco needle and reentering after hydrodissection is completed. Since we found that the nucleus was mobile enough even without hydrodissection, we did away with this altogether. On the issue of the laser actually producing the posterior capsule rent: One thing you have to be careful with, and we noticed this during our learning period, is that sometimes when you dock the interface, the lens is tilted. And when the lens is tilted, you have to be careful where you set your posterior treatment zone. You might be approaching the posterior capsule at one end, and you might just cut it. Another thing we have to be careful about, whoever is setting the machine—the technician or the surgeon—is that when you set your distances or the ends of your Maltese cross, they shouldn’t be close to your anterior capsulorhexis edge, because it can nick the anterior capsule edge, which can then extend into a tear. KRP: My comment on this is that rhexis first and fragmentation next will make the energy dissipation and the air bubbles seep into the anterior chamber. This will not put any pressure on the posterior capsule. As I would always make a 5.5-mm rhexis followed by a 4-mm crosscut, the edge of the crosscut is 1.5 mm away from the edge of the rhexis and there has never been an issue of edge tear with a laser—about 4 mm from the edge is what we do. CE: Yes, but it’s all set in the program anyway. If they want to make the software foolproof, once you set your capsulorhexis opening, the radial extent of the four cuts should be automatically adjusted so that it has enough clearance from the edge of the rhexis. GB: So you think this represents teething problems? Over a thousand cases, do you think you would have about the same number of complications or fewer? CE: I think we’ll have fewer complications. CSP: Do you think the type of interface is important? Could a flat interface cause more problems because of pressure on the cornea, compared to a liquid or curved interface? CE: Well that’s a technological issue. The point as far as we’re concerned when making a good capsulorhexis is, we just want the machine to be able to deliver the energy accurately on the proper plane. As long as you have the capsule steady and not moving about, then you’ll be able to get a complete cut. Right now, the technology is really built on that limitation, where you have to applanate the cornea and induce a certain amount of pressure in the eye. GB: One of the nuances— perhaps the most critical—of femtosecond laser cataract surgery is that it demands the use of certain skills familiar to refractive surgeons, specifically docking. If you’re an experienced LASIK surgeon, there’s going to be a short learning curve because you’re accustomed to docking, but docking is not an inconsequential or necessarily easy maneuver—it requires skill. You’re adding to every cataract surgery an additional phase of the operation. I think the type of docking interface may become a point of differentiation between the different machines. KPR: I think this is a very important point. Docking with the victus machine is the easiest thing and there is no learning curve at all. I had issues with my IntraLase docking early on, but later I found it very easy, but there is a learning curve for anyone. The victus machine that I am using has an Intelligent Pressure Control or IPC system; apart from the fact that docking itself is easy, the IPC helps you to dock without putting too much pressure on the cornea so that you don’t get get corneal folds. I’ve found that my junior colleagues adapted to docking quite easily, and I’ve found it quite easy in comparison. CE: We didn’t really have problems with the LenSx. Actually, I found it a lot easier than the docking required for LASIK. GB: Have there been suction losses? CE: Yes, but only in huge pterygia and very loose conjunctiva. This may be at least minimized if we can get a smaller interface for Asian eyes. GB: What’s the consequence of losing suction? CE: You won’t be able to go through with the corneal incisions which are done last. Depending on how much suction you lose and how soon, you might still be able to get away with capsulorhexis and the nuclear treatment. You can stop any time if you decide that it is risky to continue—although, with the present software, you have to do this manually, so you have to be paying attention to the procedure all the time. With the LenSx, docking is visual, guided by an indicator on the monitor that tells you when you have just the right amount of applanation for suction to be applied. The critical thing there is to have good exposure. If the interface touches the speculum, good docking and good suction will not be achieved. We’ve had problems with small eyes, but just by manipulating the head we were able to proceed and complete treatment. A smaller interface— better sized for Asian eyes—which we hear will be available next year, should make this less problematic. KPR: Or not use a speculum at all. I do not use a speculum at all on my IntraLase mchine, while docking. CE: Yes, eventually that might be the way to go—just use your hand to keep the eye open and dock. GB: I have heard from some centers that those who adjust to femtosecond surgery most easily are those who come from a LASIK background, whereas surgeons who have never done LASIK find the procedure more challenging. Economics, ergonomics GB: This is expensive technology and, beyond that, there are also the ergonomics and economics of a longer procedure. In our system today, the femto procedure is done in a central suite, and then the patient is taken across to the operating room, and by the time you sit down with the patient to actually perform phaco, an experienced surgeon like Prof. Chee using standard cataract surgery might already be removing her last quadrant. Is this going to be an issue? CE: It depends on how heavy your practice is. In our practice, we have a list of about 12 to 15 cases in an afternoon. What we’re thinking of doing is to perform femto and phaco in batches of two or three, after which they undergo phaco in turn. Another way we’re looking at it is that someone else will do the femto while the surgeon waits inside the operating room. GB: Would you let someone do half your operation? CE: If done by someone you have absolute confidence and trust in—why not? But it will eventually depend on how patients accept it. GB: Are there not problems with pupillary constriction? CE: Only if you place your rhexis close to the pupil. We’ve had a few such problems when we didn’t have a fully dilated pupil and the rhexis was close to it. It may also be due to the escape of the bubbles that would trigger the contraction of the pupil. We