Part 10 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)
Micro-invasive Suture Trabeculotomy (MIST)
What else can we do? Well one thing we can do is dilate the canal, the other thing we can do is say, “well, if trabecular meshwork is the primary area of restriction, why don’t we just rip it out or tear it open?” And so, we can do that. It turns out that if you’ve had a patient who’s had Ab-externo Canaloplasty and at some point the pressure is no longer controlled— if they’ve had the Stent — so, if they’ve had the suture placed in the canal, you can go in with micro-forceps or another instrument and pull the suture through. Pulling the suture through rips open the Trabecular meshwork— that’s called Micro-invasive Suture Trabeculotomy. And in a two year study it showed a 45% reduction in intraocular pressure. So, low-risk procedure.
Basically, the main risk you have is hyphema (system bleeding in the front of the eye as you open up the trabecular meshwork). That generally goes away on its own. There’s very low risk with any of these angle procedures of cyclodialysis, which can result in hypotony. That’s pretty low risk. So you know the nice thing about canaloplasty is that you can potentially get a double benefit: you can get the initial opening of the canal and then if you need to you can you know pull the suture through the trabecular meshwork.
Gonioscopy-Assisted Transluminal Trabeculotomy (GATT)
So, there’s also if you’ve got somebody who has not had Canaloplasty you can perform what’s called Gonioscopy-Assisted Transluminal Trabeculotomy. That’s essentially taking that catheter we saw before but instead of just dilating the canal you move the catheter or some people will use a aid…a suture if you want to (you know) get really cheap you don’t want to use an instrument that’s been designed for this it can be done it’s a bit more challenging but in any case you move the suture around the canal and then you take the two end of the suture and you pull through and you rip through the trabecular meshwork. And it also shows a pressure reduction around 40% at two years.
You can get more sophisticated and a whole lot more expensive; Ab-Interno Trabeculotomy has been done using a device called a Trabectome, which has to be done with or after cataract surgery. As with all of the Trabeculotomies, they do limit the potential for future canal-based surgeries but the most—the biggest issue with Trabectome is it’s just—it’s darn expensive.
This is the instrument here. And it’s a pretty cool looking instrument… it has a foot plate to protect the posterior wall of the canal and essentially it’s got these electrodes that produce plasma and then it sucks up the trabecular meshwork tissue as it opens up the canal there. So it’s about a fifty-thousand-dollar instrument and then they make you purchase each of the hand pieces so it’s not been that popular when you’ve got these other less expensive options.
Kahook Dual Blade Trabeculotomy
And one of the more interesting, less expensive options is the Kahook Dual Blade. Basically, it’s like a poor man’s Trabectome. But instead of using a plasma blade, it’s got this neat (I’ll show you) this really neat, design of this blade. There we go… that allows you to safely remove the trabecular meshwork as kind of a strip. So it strips it off. And here you can see the tip of the blade there and it’s got a kind of foot plate and then these two side blades, so you get a sharp tip to get into the trabecular meshwork. And boy, don’t I wish the trabecular meshwork looked that clear and easy to find. Angle base surgery is technically challenging. There’s a high learning curve but once you’ve got it, it can be quite fast and really gentle in terms of the patient experience.
So this is a video of the Trabeculotomy using the Kahook dual blade. And you can see the blades in the angle—It’s getting in the trabecular meshwork. Now is going to come around from the other way and it’s pretty you actually end up with this little strip of trabecular meshwork that if you were interested in it for research or other purpose you can actually take it and send it to pathology. So you can see there’s a little strip on the edge of it. They’ll actually remove that in second.
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