Eyeworld

70 | EYEWORLD | JULY 2023 G UCOMA Contact Gooi: patrick.gooi@gmail.com Grover: dgrover@glaucomaassociates.com Harasymowycz: pavloh@cliniquebellevue.com 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. Relevant disclosures Gooi: Alcon, Allergan, Bausch + Lomb, Glaukos, Santen Grover: Allergan, CATS Tonom- eter, iStar Medical, New World Medical, Nova Eye Medical, Olleyes, Reichert, Sanoculis, Versant Health Harasymowycz: New World Medical, Nova Eye Medical see the angle is abnormal. In those cases, we excise the tissue, and we find the outflow works well. Juvenile ones would often respond well to trabecular removal as well." Surgically, Dr. Harasymowycz said there are different instruments that can perform goniot- omy. Even a bent 27-gauge needle can be used, which he said is a money saver. Dr. Gooi also said it's cost effective to perform a goniotomy with a 5-0 polypropylene suture. One of the cons of the procedure, Dr. Gooi said, is the potential for postoperative hyphema, especially if a more than 180-degree goniotomy is performed. He also said that it doesn't treat outflow pathways outside of the trabecular meshwork. Canaloplasty Dr. Harasymowycz said there is still traditional canaloplasty, which is performed ab externo, but it's more common now to do ab interno canaloplasty (ABiC). This involves piercing the trabecular meshwork and inserting a cathe- ter 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 visco- canaloplasty. "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 out- flow system, but we're also creating micro-open- ings through the trabecular meshwork as well. You are addressing two things here," he said. One advantage of ABiC compared to goni- otomy, 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 pres- sure 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 viscodi- lation somewhat limited. He said many of the studies published are comprised of a relatively small number of patients with limited fol- low-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 gonioto- my compared to goniotomy with viscodilation to truly evaluate the additive effect of visco- dilation. 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 ex- panding the eye's outflow system. … It sounds like it would work, and I look forward to seeing more data evaluating the efficacy of canaloplas- ty. 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. continued from page 69

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