GLAUCOMA EWAP SEPTEMBER 2023 49 If an endothelial transplant is needed, Dr. Greenwood said, in the setting of a tube or trab, the difficulty is getting the air bubble to stay inside the eye. “It’s a battle between how well your glaucoma device is working versus keeping the gas inside the eye,” he said. “There is a little bit more education on the front end and guiding expectations.” He also said these eyes are at higher risk for pressure spikes, so heavy steroids might be used, but then you’re at risk for the glaucoma procedure to fail. “There are a couple of steps, so it may not be on optimization of the eye, but education and the aftercare gets quite detailed,” he said. Dr. Sivaraman also said that graft adherence can be more difficult in the presence of a filtering bleb or tube, and in general, the lifetime of these grafts is shorter than in an otherwise anatomically normal eye. It is important for patients to be aware that they may need repeat endothelial keratoplasty in the future. EWAP Editors’ note: Dr. Greenwood practices at Vance Thompson Vision, Fargo, North Dakota. Dr. Sivaraman practices at Cincinnati Eye Institute, Cincinnati, Ohio. Neither disclosed any relevant financial interests. (ABiC). This involves piercing the trabecular meshwork and inserting a catheter into Schlemm’s canal from which, as the surgeon removes the catheter, they dilate the canal with a bolus of viscoelastic every few clock hours, which is why it’s also called viscocanaloplasty. “The art of ABiC is when you’re injecting the viscoelastic, you can’t stay in one area and keep on injecting. That could detach Descemet’s membrane,” Dr. Harasymowycz said. Theoretically, Dr. Harasymowycz said that ABiC works by not only stretching the canal, but also the trabecular meshwork next to it. “So even if the pores are clogged, we’re increasing the size of Schlemm’s canal and dilating the outflow system, but we’re also creating micro-openings through the trabecular meshwork as well. You are addressing two things here,” he said. One advantage of ABiC compared to goniotomy, according to Dr. Harasymowycz, is that it leaves the trabecular meshwork intact and reduces the potential for blood reflux in the event there is increased episcleral venous pressure at some point. “The advantage of having a trabecular meshwork system intact is that our collector channels drain through the vessels of the eye, but if we increase episcleral venous pressure, blood can reflux into the eye. Some patients who have had trabecular excision with goniotomy, when they do exercise, even years later, have a reflux of blood into the anterior chamber,” he explained. Dr. Harasymowycz said that longer-term data is showing a lasting effect from ABiC. A retrospective, non - randomized study published in 2017 that included 277 eyes showed a mean IOP reduction from 19.7 mm Hg at baseline to 14.3 mm Hg, 14.0 mm Hg, and 15.2 mm Hg, at 1, 2, and 3 years, respectively. 1 Medication use was 0.4 drops, 0.5 drops, and 0.6 drops at these time points, down from 2.1 drops preop. Dr. Grover considers the data on viscodilation somewhat limited. He said many of the studies published are comprised of a relatively small number of patients with limited follow-up despite the fact that viscodilation and canaloplasty have been around for several years. He also said that these studies show a modest effect and usually are combined with some type of goniotomy or trabeculotomy. “There are some studies showing that goniotomy with viscodilation works moderately well. I think a great study would be goniotomy compared to goniotomy with viscodilation to truly evaluate the additive effect of viscodilation. I think the benefit of canaloplasty alone is hard to study definitively,” Dr. Grover said, adding later that he thinks “the theory of canaloplasty sounds very appealing. You’re expanding the eye’s outflow system. … It sounds like it would work, and I look forward to seeing more data evaluating the efficacy of canaloplasty. Now that there is a device available that can perform ab interno canaloplasty with a minimal goniotomy, I expect to see more pure canaloplasty data published.” Dr. Gooi said he thinks the pros of ABiC are that it’s potentially repeatable and it can provide real-time aqueous venography. The cons are that it has less IOP-lowering potential if performed without goniotomy, and it is slightly more challenging to set up in the OR. EWAP Reference 1. Khaimi MA, et al. An analysis of 3-year outcomes following canaloplasty for the treatment of open-angle glaucoma. J Ophthalmol. 2017;2904272. Editors’ note: Dr. Gooi practices at Cloudbreak Eye Care, Calgary, Canada, and has interests with Alcon, Allergan, Bausch + Lomb, Glaukos, and Santen. Dr. Grover is Attending Surgeon and Clinician, Glaucoma Associates of Texas, Dallas, Texas, and has interests with Allergan, CATS Tonometer, iStar Medical, New World Medical, Nova Eye Medical, Olleyes, Reichert, Sanoculis, and Versant Health. Dr. Harasymowycz is Associate Professor, University of Montreal, Quebec, Canada, and has interests with New World Medical and Nova Eye Medical. Making...for Navigating - from page 43
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