JAN 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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48 EW GLAUCOMA February 2011 January 2012 Alternatives to trabeculectomy by Faith A. Hayden EyeWorld Staff Writer An overview of what's available I t's no secret that trabeculec- tomy, the so-called "gold standard" of glaucoma surgery, has been called some pretty nasty things of late by glau- coma surgeons. Everyone, it seems, is desperate for an alternative to the procedure, which was first consid- ered contemporary when Lyndon B. Johnson was in office. It may be the most effective glaucoma surgery for lowering intraocular pressure, but it also comes with the highest risk of complications. So what are the alter- natives? And can any usurp tra- beculectomy from its battered and beleaguered throne? EyeWorld spoke to experts on the Trabectome, canaloplasty, endo- scopic cyclophotocoagulation (ECP), the EX-PRESS, and the iStent to gar- ner a closer look at what makes each alternative tick, as well as some of the scientific data backing up their efficacy. Trabectome The Trabectome procedure (NeoMedix, Tustin, Calif.) gained FDA approval in 2004 for the treat- ment of open-angle glaucoma, and it's best suited for mild to moderate cases. According to a comprehensive article on Trabectome by Steven D. Vold, M.D., founder and chief exec- utive officer, VoldVision, Springdale, Ariz., the procedure has a number of safety advantages over trabeculec- tomy, such as no bleb creation, which eliminates blebitis and other related complications; no require- ment for using mitomycin-C or 5- fluorouracil; and it does not require the dissection of the conjunctiva or sclera, leaving the door open for future glaucoma surgeries (Interna- tional Ophthalmology Clinics, 51:65- 81). During the operation, a surgeon makes a 1.6-1.7 mm temporal clear corneal incision with a keratome. Dr. Vold suggested injecting viscoelastic to help stabilize the anterior cham- ber. The surgeon then ablates the tra- becular meshwork and Schlemm's canal, while maintaining irrigation throughout the ablation process, thus minimizing the risk of thermal dam- age to surrounding tissues. Post-op photos for a patient with the EX-PRESS in the anterior chamber with superior bleb Source: Sarwat Salim, M.D. "Failure is probably the first complication you need to talk about," said Dr. Vold. "It doesn't work in everyone. Hyphema has to be minimized. There's talk of if we should use anticoagulants or not. I personally think that in this proce- dure it's best to stop anticoagulants if possible for a small period of time, just to prevent a large hyphema at the time of surgery. Some people use viscoelastic to tamponade the sur- gery to minimize blood. That's a rea- sonable option. I think pressurizing the eye at the conclusion of the case is an important thing." Although there haven't been many peer-reviewed, prospective, randomized trials of the Trabectome, case study data has been encourag- ing thus far. A pilot study, for exam- ple, involved 37 patients who had the procedure at CODET Eye Insti- tute, Tijuana, Mexico (Ophthalmol- ogy, 2005; 112:962-967). After the surgery, patients had a 40% drop in IOP levels overall. Mean IOP de- clined from pre-op levels of 28.2±4.4 to 16.3±2.0 mm Hg (n=15) at 12 months post-op, and medication use decreased from 1.2±0.6 (n=34) to 0.4±0.6 at 6 months post-op (n=25). "All hyphemas cleared within 6.4±4.1 days," stated Dr. Vold's paper. "Other complications in- cluded peripheral anterior synechiae (24.3%), corneal injury (16.2%), focal iris adhesion to spur or poste- rior meshwork (13.5%), and pressure spike (post-op IOP >5 mm Hg above baseline) (5.4%). Vision loss did not exceed 2 Snellen lines in any pa- tient. No serious, vision-threatening complications were observed." The two biggest benefits of the Trabectome, said Dr. Vold, are its safety profile and the fact that the procedure spares the conjunctiva. Furthermore, it does not negatively impact the results of a future tra- beculectomy, should the Trabectome fail. "It's a growing procedure," he said. "It's picking up some steam in the U.S. I think the whole space of minimally invasive glaucoma surger- ies, where we're doing conjunctive sparing surgeries, is an area that's about to explode. Moving from a fil- tration surgery to surgeries that do not create a bleb is going to be the wave of the future." Canaloplasty Canaloplasty is a non-penetrating and minimally invasive procedure for open-angle glaucoma that works by dilating and stenting Schlemm's canal, stretching the trabecular meshwork, and opening up De- scemet's membrane, allowing fluid to flow through the window out. The procedure will not work on patients with angle-closure glau- coma and is best suited for open- angle patients who need a pressure in the mid- to high teens. "If patients are losing vision with a pressure of 40, canaloplasty works well," said Richard A. Lewis, M.D., cataract surgeon and glau- coma specialist, Sacramento, Calif. "If they're losing vision with a pres- sure of 18, then you might not get as much pressure reduction as you would with a trabeculectomy. Our studies show that the average pres- sure ends up around 15. If you want the pressure down to 12, it's hard to do that predictably with this proce- dure." Dr. Lewis and colleagues pub- lished 3-year follow-up results on the procedure in the April 2011 issue of the Journal of Cataract & Refractive Surgery (2011; 37:682-690). "Canaloplasty led to a signifi- cant and sustained IOP reduction in adult patients with open-angle glau- coma and had an excellent short- and long-term postoperative safety profile," it stated. Early complications included a 12.1% incidence of microhyphema and a 0.6% incidence of hypotony. No patients had flat/shallow anterior chambers or choroidal detachment. Late complications were infrequent and included four observed blebs at 36 months with no long-term bleb- related issues. According to Dr. Lewis, naysay- ers criticize the procedure as being too difficult to do. "They think it's too hard and are skeptical of the way it works," he explained. "It's not that hard, but the perception is that it is. It takes some practice getting the skill set. We have to put the catheter stent in the canal, and many who are critical have not taken the course. But they take the course and learn how to do it." Dr. Lewis is impressed with the 3-year results he and his colleagues recently published. "It's held up pretty well," he said. "Every glau- coma procedure presents problems in long-term follow-up—all of them. An example of a canaloplasty Source: Richard A. Lewis, M.D.

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