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Part 9 of 14 of “Adjusting the Faucet or Opening the Drain – Currently Available Methods to Treat the Plumbing Problem of Open Angle Glaucoma” | A San Gabriel Valley Optometric Society (SGVOS) Continuing Education Dinner Event – 2 hours CE | Featured Speaker: Dr. David Richardson, MD | April 12, 2017
Currently Available Incisional Treatments for Glaucoma (Lower Risk Surgeries)
Ab-Interno or Minimally Invasive Glaucoma Surgery (MIGS)
So moving on to the minimally invasive glaucoma surgeries, which is really an exciting area right now—but the question is, “are they also minimally effective?”
So the ones we’re going to go over are the ones that are FDA-approved: Ab-interno Canaloplasty (ABiC)—so this is Canaloplasty from the inside of the eye, Trabeculotomy, iStent®, Cypass®, Xen Gel Stent, and Cataract Surgery. And you may say, “well, why’s cataract surgery up there?” We will get to that.
So interestingly enough, with the Ab-Externo Canaloplasty (coming from the outside) they separated the results in those that had the stent and those that didn’t have the stent. And what they saw was that, although they generally did better with the stent (even if you couldn’t get the stent in) the pressure is still dropped. And you can see in this here three-year results of those with Ab-Externo Canaloplasty but without the suture the average pressure dropped from 25.2 mmHg to 16.2 mmHg. This is a pretty decent reduction and the mean number of medications from 2.1 to 1.1— so by one medication on average.
So, Dr. Mark Gallardo in El Paso Texas thought, “well this is interesting. Is there a way that we could do this from the inside of the eye without making the incision from the outside the eye, which would make it much less complex of a surgery and also a much faster surgery. And it turns out you can and the neat thing about it is that by doing this you treat the trabecular meshwork—because you create an opening in the trabecular meshwork, you open Schlemm’s canal, you potentially dilate the collector channels— so you get better aqueous outflow, and there’s no permanent stent or implant. And that’s the key point of the Ab-Interno Canaloplasty— no permanent stent or implant.
What we’ll do here is I’m going to take us through—this here, so essentially this is after cataract surgery. So, what’s going to be done is— you can see over here that…here’s—the catheter is being inserted into the anterior chamber and it’s basically being rested against the angle here. Then what happens is a gonio lens is placed on the eye—and here again you can see that the catheter is resting there so you’re looking at the angle of the eye—and either a blade or Cystitome is used to actually pierce the trabecular meshwork, opening up into Schlemm’s canal, which also—which often results in a little blood reflux—so you can see a little blood there. And then this is what is so cool about this procedure—micro forceps are used to thread this catheter through and you can see the tip of the catheter (it’s a blinking red catheter), you’re going to see it coming around here in a moment—so these—he’s threading it around to the Schlemm’s canal. So he’ll thread it all the way around and then place another instrument in the eye to essentially hold the catheter up against the angle and he pulls it back through. As it’s being pulled back through, viscoelastic is being injected into the canal—dilating the canal.
So how does it work? Well, the initial studies, looking one year out basically showed—there’s two: one was by Dr. Khiami, showed a reduction of from 19.5mmHg to 13.9mmHg. The reduction of average medications from 2 to 0. Dr. Gallardo, showed a reduction of 18.6mmHg to 12.9 mmHg. You get 12.9 mmHg! I mean, that is in the range of what the Trabeculectomy studies are showing, right? And mean reduction from 2 medications to 1. And if you actually combine the studies—mean IOP from 19 mmHg to 13.3 mmHg, 2 meds to 1. You know these are very impressive results for very safe and very fast surgery.
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Currently Available Methods to Treat Open Angle Glaucoma Series:
- Currently Available Methods to Treat Open Angle Glaucoma
- Beta-blockers, Selective Alpha Adrenergic Agonist, CAIs
- Prostaglandin Analogs, Cholinergic Receptors Agonists, Fixed Combination Agents
- Carbonic Anhydrase Inhibitors (CAIs)
- Laser Trabeculoplasty
- Continuous Wave and Micropulse® Cyclophotocoagulation
- Trabeculectomy and Glaucoma Drainage Devices
- Ab-Externo Canaloplasty
- Ab-Interno Canaloplasty
- IStent®, Cypass® Microstent, Xen® 45 Gel Stent, Cataract Surgery
- Next-Generation Glaucoma Medications and Surgeries
- iStent Supra®, Hydrus™ Microstent, and InnFocus MicroShunt®
- Canaloplasty with Stegmann Canal Expander