EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78721
February 2011 January 2012 EW GLAUCOMA 49 That's the nature of this disease. I don't think we've hit the nail on the head in terms of a perfect surgery. Until that time, canaloplasty is a great way to avoid complications." ECP ECP is a surgical glaucoma proce- dure typically used in conjunction with cataract surgery for glaucoma patients with controlled IOP. How- ever, in recent years it's also been safely done as a standalone proce- dure in combination with a pars plana vitrectomy. If a patient has al- ready been implanted with a tube or had a failed trabeculectomy, a proce- dure called ECP Plus is an option. "There's a paper by Brian Francis, M.D., that looked at pa- tients who had a barbell tube and questioned if we want a second tube or an ECP," said Robert Noecker, M.D., vice chair, ophthalmology de- partment, University of Pittsburgh Medical Center Eye Center. "What he showed was that ECP was a good alternative to doing a second tube in those patients who failed one tube already." The paper, published in the October/November 2011 issue of the Journal of Glaucoma (20:523–527), reported the results of a prospective, non-randomized clinical trial that included 25 eyes of 25 consecutive glaucoma patients with a previous tube shunt and uncontrolled IOP. Patients had a pre-op IOP greater than 21 mm Hg. "At 12 months, the mean IOP dropped from 24.02 to 15.36 mm Hg," the report stated. "The mean of the differences was −7.77 mm Hg (−30.8%). The mean number of medications was 3.2 before laser and 1.5 at 12 months (P<0.001). The suc- cess rate at 12 months (n=18) was 88% and remained at that level until the end of the follow-up period of 2 years (n=11, P<0.00005). There were no serious complications." "The results were excellent, with about 80% success at 1 year and be- yond," said Dr. Francis. "With this procedure we avoid the possible complications of a second tube such as strabismus (with a superior nasal tube) or erosion (with an inferior tube)." Dr. Francis walked away with some other pearls from the study. "Be prepared to cause and treat in- flammation," he said. "We use IV steroids, intracameral preservative- free steroids, as well as frequent topi- cal and sometimes PO steroids. Some patients have very disrupted anatomy with limited access to the ciliary processes, especially via a standard anterior approach. For some, we recommend a pars plana approach combined with complete or partial vitrectomy." Finally, he said, "Use caution when treating NVG or uveitic glau- coma. Some of these patients get in- flammation that is chronic and may get hypotony." According to Dr. Noecker, the great thing about the ECP/cataract surgery combination is that the cataract incision is already made and the ECP probe simply goes into that incision. "What we do is try to ablate the ciliary body as much as we can from the front side," he said. "The good and bad thing about that approach is the most we can treat is about 50% of the ciliary body. We can't overtreat because we can't get to it all. The only thing worse than high pressure is low pressure. At the same time, it's limited. The best you can do is get a pressure into the mid- and upper teens." For patients with mild glau- coma, that pressure reduction may be enough. Furthermore, for patients who are on multiple glaucoma med- ications, it's realistic to expect that ECP will get them off the medica- tion. There is a learning curve to the procedure, however, which may frustrate and deter some surgeons. "Most of the problems come from overtreating and inexperience in recognizing it," said Dr. Noecker. "If you overtreat, what happens is you basically cause too much heating in one area and you get an explosion. That will cause inflamma- tion." Experienced surgeons will do more of a painting and continuously move across the ciliary body. That way they aren't in one spot too long, causing a burn. What a sur- geon should be doing is treating the whole area, but that comes with ex- perience. "Some people get frustrated be- cause they undertreat and don't get enough IOP lowering, so it's not ef- fective," he said. "Then they'll overtreat and get these explosions. In the past, the procedure has been oversold as really easy, but to get the optimum results, it takes some fi- nesse." The EX-PRESS Glaucoma Filtration Device The EX-PRESS Glaucoma Filtration Device (Alcon, Fort Worth, Texas) is a biocompatible, stainless steel, non- valved device placed under a partial thickness scleral flap to drain the aqueous humor from the anterior chamber to the subconjunctival space. It forms a traditional filtration bleb after a standard trabeculectomy. The IOP control with this device is reported to be comparable to that of a standard trabeculectomy. The major difference though, said Sarwat Salim, M.D., associate professor of ophthalmology, and di- rector of the glaucoma service, Uni- versity of Tennessee, Memphis, is the complication rates. Post-op com- plications from the EX-PRESS are similar to that of a trabeculectomy and include hyphema, hypotony, shallow or flat anterior chamber, choroidal effusions, and on rare oc- casions, suprachoroidal hemorrhage, but are much less overall. "Fewer complications with the EX-PRESS device are attributed to more controlled aqueous humor flow through a consistent lumen size unlike trabeculectomy where sclerotomies made with a punch or scissors may be of different sizes and translate into unpredictable aqueous flow and outcomes," wrote Dr. Salim in her article "EX-PRESS Glaucoma Filtration Device Surgical Technique and Outcomes" (Int Ophthalmol Clin 2011 Summer; 51:83-94). Complications unique to the de- vice include erosion and extrusion, which have been minimized but not eliminated by placing the EX-PRESS under a partial thickness scleral flap. "From my clinical experience I have noticed thinning of the sclera over the device in some cases," said Dr. Salim. "There is a possibility that these cases may erode with time, and a longer follow-up will help us better understand this potential complication." The most common device-re- lated complication in one large ret- rospective study was occlusion of the lumen, which was not visible on clinical exam. "When you examine the tip of the device in the anterior chamber during the slit lamp exam, you don't see the blockage," she said. "But the reason you know it's blocked is be- cause the bleb is flat and IOP is high." To alleviate the obstruction, Dr. Salim suggested liberating the fibrinous particles or debris with a Nd:YAG laser, which restores aque- ous outflow through the device and results in an elevation of bleb height and a lowering of IOP. Benefits of the EX-PRESS include a rapid learning curve, less inflam- mation since there is no tissue re- moval, predictable outcomes related to consistent lumen size and con- trolled flow, lower intraocular pres- sures post-op, and fewer post-op complications. "Although the current literature reports favorable outcomes, the long-term safety and efficacy of this device have yet to be determined," wrote Dr. Salim in her paper. "The ongoing prospective, randomized clinical trial, XVT, will elucidate ad- ditional information comparing this latest modification to the standard trabeculectomy." iStent The iStent Trabecular Micro-Bypass (Glaukos, Laguna Hills, Calif.) is the first ab interno micro-bypass im- plant for the treatment of glaucoma. It's currently CE marked and avail- able for use in select countries in Europe and was approved for use in Canada. However, the device is still awaiting FDA approval in the U.S. and has been for some time. continued on page 50 EyeWorld factoid Glaucoma accounts for slightly more than 12% of all global blindness Source: World Health Organization