DEC 2013

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

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30 EW GLAUCOMA December 2013 February 2011 Device focus Diode lasers not just for end-stage treatments by Michelle Dalton EyeWorld Contributing Writer Some glaucoma specialists believe lasers have a place much earlier in the treatment paradigm T ransscleral cyclophotocoagulation (TCP) applies laser treatment to the ciliary body with an aim of lowering the pressure by decreasing aqueous production. Surgeons have used the 810-nm wavelength in both transscleral and endocyclophotocoagulation (ECP), the latter of which is typically used in combination with cataract surgery to lower IOP and reduce dependence on glaucoma medications. Earlier cyclodestruction methods included cyclectomy, diathermy, ultrasonic energy, and cryotherapy, but the potential side effects—including relatively high rates of hypotony and vision loss—offset the gains in IOP reduction. Although TCP and ECP use the same wavelength laser, and both lower IOP by decreasing ciliary endothelium function, they differ widely in their approach and, to some extent, the types of patients who are best served by each. Some clinicians believe all uses of ciliary ablation are for end stage cases, said Steven R. Sarkisian Jr., MD, glaucoma fellowship director, Dean McGee Eye Institute, and clini- cal associate professor, University of Oklahoma, Oklahoma City. "However, ECP is best performed in early to moderate glaucoma, and TCP is best after other procedures have failed," such as trabeculectomy filtering surgery or tube surgery. In TCP, the surgeon uses a contact G-probe (Iridex Corp., Mountain View, Calif.), which Dr. Sarkisian deemed a "game changer" over cyclo-cryoablation because it helped surgeons better target the end-organ tissue. "In terms of effectiveness, a trabeculectomy, a tube shunt, and TCP typically achieve more IOP lowering than ECP, but they also have higher complication rates," said Parag Parekh, MD, in private practice, Laurel Eye Clinic, Brookville, Pa. "With ECP, I usually get a moderate effect—somewhere between 0 and 10 mm Hg; I average around 5-7 mm Hg. ECP is very convenient and safe to do in conjunction with cataract surgery, so phaco-ECP has become my go-to surgery for phakic patients with glaucoma." Comparing transscleral to ECP Endoscopic cyclophotocoagulation showing treated and untreated ciliary body on the monitor and the laser unit Source: Marty Uram, MD Dr. Parekh said with the advent of ECP and other MIGS procedures such as the iStent, he will rarely perform a trabeculectomy as a first line surgical procedure for primary open angle glaucoma, at least not before giving phaco-ECP and/or iStent a chance to be effective. "If it was my own eye, I'd want to give the least invasive procedures a try first," Dr. Parekh said. ECP is "totally different from transscleral," Dr. Sarkisian said. "TCP treats the entire ciliary body, and also affects any nerves that happen to be in the way." Because the laser emits the energy onto the sclera the procedure is "far more inflammatory" than ECP and, therefore, comes with higher potential complications and risks. Dr. Parekh recommended surgeons "go gingerly" when using TCP. "Titrate it to where you need the pressure to be. If you overdose on the laser, you could end up with hypotony; it's better to have to do a 'light diode' twice than overdoing it on the first round. It's a quick procedure—20 shots at 2 seconds each after a retrobulbar block; it's low-risk overall and with no real risk of infection. Furthermore, follow-up is simple for the patient," he said. Dr. Parekh has begun using TCP more in earlier stage patients—particularly those in whom he believes are too frail or who have exhibited poor compliance or are unlikely to have a successful trab. "I have a fair number of 90-year-olds who have excellent acuity but IOP that was elevating out of control. I didn't think they could handle a tube or a trab, so I performed a 'light diode TCP'. Afterward, their vision remained excellent, IOP came under control, and they even came off a few of their drops, and were very grateful for their outcome," Dr. Parekh said. Dr. Sarkisian said he's performed "gentle" or "limited" TCP on patients with vision better than 20/80 and "none have lost vision." If, however, patients are overtreated, vision loss after TCP is a risk. With TCP, the high risk of macular edema and inflammation need to be weighed against the improvement in pressure. ECP, on the other hand, produces little risk of macular edema beyond what cataract surgery can produce, Dr. Sarkisian said. Dr. Parekh added, "Let's not forget that the data shows that trabeculectomy and tube shunt patients often have decreased vision after those procedures as well. All of our 'heavy duty' glaucoma procedures risk at least some vision loss." Optimizing use Some highly informed patients who truly understand the pros and cons of trab and tubes may request TCP earlier than most glaucoma specialists would recommend it. "ECP is less effective than TCP, but it has an outstanding safety profile," Dr. Parekh said. "The biggest downside is if there's not enough pressure lowering. There are very few true adverse events or complications. "TCP may be more effective, and I think it has fewer side effects than most people think," Dr. Parekh said. Dr. Sarkisian said phaco-ECP is a reasonable first-line procedure but continues to reserve TCP after patients have failed other treatments. "When you've run out of conjunctiva, TCP is the way to go," he said. "Or when patients have very continued on page 32

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