EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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80 EW FEATURE February 2011 Combined glaucoma and cataract surgery October 2013 Trabectome in combined surgery by Maxine Lipner EyeWorld Senior Contributing Writer AT A GLANCE • Surgeons find the Trabectome is a natural for glaucoma patients and even enables premium lens implantation. • In addition to mild-to-moderate glaucoma cases, some are using the Trabectome in more advanced and even end-stage cases. • While some reserve the Trabectome to treat just a few clock hours, others are using it on up to 180 degrees of trabecular meshwork. Latest techniques and expectations W hile many have heralded the call of the iStent (Glaukos, Laguna Hills, Calif.) for mild-to-moderate glaucoma patients with cataracts, some are reaching for the Trabectome (NeoMedix, Tustin, Calif.) instead. Garry P. Condon, MD, associate professor, College of Medicine, Drexel University, Pitts- burgh, is one such surgeon. "Right now the Trabectome is the only form of microinvasive glaucoma surgery that I'm doing," Dr. Condon said. Others are also opting for the Trabectome in different cases. Here's where the technology stands. Nils A. Loewen, MD, assistant professor of ophthalmology, University of Pittsburgh Medical Center (UPMC), Pittsburgh, describes the Trabectome as a plasma surgery technique. "It creates at the tip something called pico lightning, and it ablates the structure that guards the drainage system of the eye," Dr. Loewen explained. "There's a strainer tissue, the trabecular meshwork, and this little plasma bubble that the device creates at its tip essentially disintegrates the strainer so there is a free flow into the drainage system." The Trabectome technique, according to Ronald L. Fellman, MD, Glaucoma Associates of Texas, and associate clinical professor emeritus, University of Texas Southwestern Medical Center, Dallas, is an outgrowth of the old trabeculotomy procedure, which would cleave open Schlemm's canal and the trabecular meshwork. Unfortunately, success with the procedure was short lived for adults. "In adults postoperatively, those little scrolls, or lips or leaflets, would reapproximate and the operation would gradually fail over a period of months," Dr. Fellman said. However, this is not so with the Trabectome, which Dr. Fellman explained removes a strip of tissue, instead of cleaving it open, making it impossible for it to reapproximate. Cataract surgery contenders Dr. Fellman finds the Trabectome, which allows practitioners to use an ab interno approach without violating the conjunctiva or the sclera, to be a particularly good match in conjunction with cataract surgery. "It goes through the same incision as cataract surgery," Dr. Fellman said. Cataract surgery itself he views as almost like a miracle allowing the patient to see right away. "If possible you don't want to do any glaucoma operation that messes that up," he said. During the irrigation and aspiration phase of the cataract procedure, it is possible to check on what he terms the "episcleral venous fluid wave" in the area hopefully just opened up by the Trabectome. After first taking your foot off the phacoemulsification pedal, during which time the vein fills up because the pressure in the eye goes down to zero, you then do the opposite. "You put your foot on the (phacoemulsification) pedal and all of a sudden the fluid rushes down into the anterior chamber—you can actually see it go into the collectors," Dr. Fellman said. This confirms intraoperatively that you have already increased the flow and its likely a good prognostic sign that the patient is going to do well. Dr. Loewen agreed that the Trabectome is a natural with cataract surgery, noting that you might have better vision than with classical surgeries since it doesn't induce any significant astigmatism. "You can predict the small amount of astigmatism that any anterior segment surgery induces and because of this you can implant so-called premium lenses to neutralize astigmatism," he said. "No one would put in the toric lens at the time of trabeculectomy or tube shunt surgery simply because continued on page 82 Meeting continued from page 79 geons during the first few uses of the lens when implanting iStents, Dr. Hill said. Dr. Hill has a few pearls to share for use of the lens. 1. Aim for excellent visualization of the trabecular meshwork. "Most people don't tilt the head or operating microscope over far enough. If you can't see the meshwork, you can't put the lens in easily," he said. 2. Practice before doing MIGS. "At the end of cataract surgery, roll a patient over and put the lens on the eye or touch the meshwork with a Sinskey hook or something similar to get used to the dimensionality of the lens," he advised. 3. A coupling viscoelastic can help visualize the anterior chamber angle and prevent air bubbles in the lens corneal interface. 4. Lower IOP to allow reflux of blood into Schlemm's canal to improve visualization with faintly pigmented trabecular meshwork. Using endoscopy for iStent implantation Nathan M. Radcliffe, MD, assistant professor of ophthalmology, Weill Cornell Medical College, New York, faced a problem that other surgeons have likely encountered. He had two gonio lenses, but he had three scheduled surgeries in one day that would require use of those lenses. He asked someone in the OR if they could sterilize one of the lenses for later use—but found out the sterilization process would take longer than he had hoped. Dr. Radcliffe had already used endoscopic cyclophotocoagulation (ECP) with some of his iStent cases, which gave him an idea to use the endoscopy camera with that additional case. "I did ECP and had a beautiful view of the angle through the main incision with a 20-gauge curved endoscopy probe, then I slid the injector for the iStent in the wound right next to it. On my first attempt, I put the iStent into the trabecular meshwork," he said. Since then, Dr. Radcliffe has used the endoscopy camera to achieve successful iStent placement in about six cases. The main advantage has been excellent visualization. "The field of view is narrower so you don't see the whole eye. You're looking at 3 clock hours, but visualizing details of the meshwork anatomy is fabulous," he said. The approach can also save a few minutes of surgical time. Still, it can be more technically challenging to have both the endoscope and the iStent sometimes pushing against each other, he said. He noted that he attempted but was unable to implant the iStent endoscopically in about three cases. That said, Dr. Radcliffe said he performs a lot of endoscopy and will most likely use this approach again in cases where he is performing both ECP and iStent implantation. He also imagines situations where he takes a traditional surgical approach but might decide to switch to use of the endoscope for better visualization. Although he has obtained a few more gonioscopic lenses, the use of the endoscope also may come in handy if he is once again in a surgical crunch, with a certain number of iStent cases but not enough gonio lenses on hand to accommodate them all. EW Editors' note: Dr. Hill is the inventor of the Ocular Hill Surgical Gonioprism and a founder of Glaukos. Dr. Vold has financial interests with Glaukos, NeoMedix, Transcend Medical (Menlo Park, Calif.), and other ophthalmic companies. Dr. Radcliffe has no financial interests related to this article. Contact information Hill: 714-542-0111, ocg@mac.com Radcliffe: 646-962-2020, nmr9003@med.cornell.edu Vold: 479-442-8653, svold@cox.net