With a broad array of new, simpler, safer procedures and advanced new devices with which to accomplish them, the stars are better aligned than ever for glaucoma surgery. Although our therapies are still not perfect, we are now able to intervene earlier, produce better outcomes, improve patients' lives and actually save the health care system money. For surgery facilities, I see tremendous current and future opportunity in glaucoma treatment. If your facility hosts eye procedures but you are not offering a full range of glaucoma treatments, I urge you to investigate the possibilities.

Trabeculectomy improvements

When many of us think about glaucoma surgery, we think about trabeculectomy. Until about 15 years ago, that was our bread-and-butter approach. Glaucoma occurs because the channels that allow aqueous to flow out of the eye become less efficient. This procedure, like most, is aimed at correcting that problem. Trabeculectomy involves opening the conjunctiva, dissecting the sclera and then making an incision under a scleral flap, into the anterior chamber and removing a piece of the peripheral iris to allow fluid to flow out. Our "Gold Standard" procedure is about as elegant as drilling a hole in the side of a bathtub and placing a bucket next to it to collect the water.

When it works, it can work well, but sometimes pressure drops too much, resulting in a potentially devastating condition called hypotony. The conjunctival bleb can scar down, stopping outflow. Also, because there's an open communication, these patients are at lifelong risk for endophthalmitis. Trab-eculectomy patients also take as long as 3 months to heal.

In the early 2000s, Optonol (later bought by Alcon) introduced the Ex-Press, a tiny stainless steel shunt that made trabs somewhat better. Instead of relying on a passageway made of tissue, the Ex-Press allows us to channel the fluid through a 50 or 200 ? shunt. The Ex-Press helps prevent hypotony, but the other disadvantages of trabeculectomy remain. Physicians continue to use this procedure for patients who are failing other therapies, but it has been slowly declining in popularity.

That could change with a new device on the horizon, the InnFocus by Santen. It bears resemblance to the Ex-Press in that it allows fluid to escape and drains into the sub-conjunctival space and involves an ab externo incision, but no flap is required and the stent is longer so hypotony is even less common. Moreover, it's made out of SIBS, the same material used for some coronary stents. It's very biocompatible and cellular material doesn't stick to it.

Micro Invasive Glaucoma Surgery (MIGS)

In 2012, a renaissance began in glaucoma treatment. That's when the FDA approved the first of 3 new stents that could be implanted ab interno, or from the inside of the eye. These new devices offered many advantages. For one thing, they didn't require time-consuming conjunctival manipulation. For another, they promised robust but well controlled outflow. Implanting them required surgical skill, but they were straightforward enough that trained general ophthalmic surgeons could implant them.

The first approved, called the iStent, is simply a microscopic titanium tube that the surgeon inserts through the trabecular meshwork and into the canal of Schlemm. Once implanted, it creates a patent, controlled outflow channel for aqueous. Rather than drilling a hole in the bathtub, here you are bypassing the obstruction in the drain with a stent, restoring natural function. It's approved for use during cataract surgery, and when you do both procedures together, you can expect a significant eye pressure drop. For patients who are well-controlled on 1 to 2 medications, this device often lowers pressure enough to stop medications. That is a huge benefit, because medications are expensive, patients sometimes don't have the manual dexterity to instill them or they have trouble remembering. Studies show that compliance with glaucoma medications is only about 50%.

The iStent has been a big hit. Four years after its introduction, there were about 3 times as many iStent procedures annually as trabeculectomies.

A year ago the iStent got a competitor, Alcon's CyPass. This stent is 6.3 mm long and used to bypass the canal of Schlemm outflow pathway and carry aqueous directly to the suprachoroidal space, where it can exit via the sclera and choroidal blood vessels. At the distal end, the tube is fenestrated so that the aqueous fluid gets diffused evenly. The CyPass is also approved for use during cataract surgery. In a pivotal U.S. clinical trial, among those who responded, 93% of patients were able to stop their medications.

Most recent is the Xen, from Allergan. This cross-linked gelatin stent uses the same general aqueous egress pathway as a trabeculectomy, Express and InnFocus, with one major exception: It starts at the anterior chamber and ends under the conjunctiva. This device allows an ab-interno approach, meaning that we don't have to do the extensive dissection and suturing as we do with a trabeculectomy. The stent, made of porcine material, is 6mm long, so the blebs these devices form are large, flat and positioned more toward the back of the eye — all good qualities. Because of its 45 ? diameter as well as its 6mm length, outflow is predictable. Clinical trials have shown it to reduce IOP by about 7 mmHg. Significantly, the FDA approval for this stent does not require that it be done in conjunction with cataract surgery. You can do it under topical/intracameral lidocaine. I believe once this procedure starts to gain traction, the number of trabeculectomies will decline precipitously.

Because all 3 stents have different mechanisms of action, I sometimes use more than one to get the amount of pressure lowering I need. Occasionally that can cause a reimbursement issue, but if the patient is willing to pay for the procedure privately it's not a problem.

We could see more stents soon: Glaukos's iStent Supra, which strongly resembles the CyPass, and also the iStent Inject and Infinity. The first employs 2 stents with cataract surgery and the second features 3 stents as a standalone procedure.

Canaloplasty and goniotomy/trabeculotomy

Since 2008, surgeons have also been able to use canaloplasty to clean out and expand Schlemm's canal. This procedure might be akin to using a roto-rooter to clean out a sluggish drainpipe underneath the shower. A medical analogy would be angioplasty.

When this procedure started out, we used a tedious external approach that was supremely difficult and time consuming. It was not considered minimally invasive. Since then surgeons have discovered that they can also do this procedure with an ab interno approach, which is more efficient and can be classified as MIGS. To do the newer technique, the surgeon makes an incision as one would for cataract surgery, using a surgical gonioprism to visualize the angle anatomy, dissects an opening into the canal and then feeds an ultra-thin catheter all the way around the circumference of the canal back to the opening to fill the canal with viscoelastic. The iTrack device from Ellex includes a lighted tip so that you can see your progress. This can also be done with a device called VISCO360 from SightSciences. The iTrack was designed for ab externo use and was not originally indicated for ab interno, but has been effectively used in an ab interno fashion for a few years now. The VISCO360 is on label for an ab interno indication and was designed from its inception as such.

Another approach is to unroof the canal by removing part or all of the trabecular meshwork that covers it. This can be done with a suture, or more reliably with the iTrack catheter mentioned above or another device from Sight Sciences called the TRAB360. These devices remove the entire 360 degrees of canal, lowering IOP by about 2-3 mmHg more than if you only remove part of the meshwork. However, removing only part of the meshwork is also effective. Two techniques that partially remove the trabecular meshwork include the Kahook Dual Blade (New World Medical) and the Trabectome device (Neomedix). The latter has the disadvantage of a large capital cost. However, the device offers the distinct advantage of being able to inject and aspirate saline to maintain the anterior chamber. Finally, the FDA has just approved a new device from SightSciences called the OMNI system that essentially does both VISCO360 and TRAB360 at the same time. The approval is for both indications, so the surgeon and facility are able to bill for both goniotomy (65820) and canaloplasty without stent (66174) while also being in compliance with FDA labeling and Medicare billing regulations.

Laser procedures

In addition to invasive glaucoma surgery, there's a relatively new development in non-invasive laser surgery. It's called micropulse transscleral cyclophotocoagulation. It mimics a procedure we do called endocyclophotocoagulation. The difference is that you can do this procedure with a diode laser from outside the eye with no incision.

I usually do this in my ASC with sedation, without a nerve block, since there is little post-op pain and the sedation lasts as long as the laser treatment. The surgeon applies the laser energy in a painting motion along one hemisphere at a time, avoiding the ciliary plexus at 3:00 and 9:00. The laser, called the Cyclo G6 from Iridex, applies pulsed energy to the ciliary processes. These are the vascular folds on the inner surface of the ciliary body that produce aqueous humor. In one study, the treatment lowered IOP by about 30%, and let patients drop a medication. The same laser can also do a more aggressive type of treatment using a "G-Probe" that treats the same area with a higher amount of energy that is not pulsed.

If these developments come to pass, we'll be doing surgery on an even greater percentage of glaucoma patients.

An alternative treatment is endoscopic cyclophotocoagulation, or ECP. This lasers the same area, but does it through a cataract incision and allows you to see the ciliary processes on a monitor. Really, ECP is the first MIGS procedure in that it lowered IOP safely through a small incision.

The future

Some exciting new technologies are on the horizon. I'm especially hopeful about devices that feed glaucoma medication into the eye over the long term, without the need for drops. Glaukos is in Phase II with the iDose, a microscopic canister containing anti-glaucoma medication. You inject the canister into the anterior chamber and it elutes medication. I will be presenting one-year data for the iDose at the upcoming meeting of the American Glaucoma Society. Ocular Therapeutix is testing an intracanilicular device that similarly releases medication for 90 days. That company is also testing an intracameral device that accomplishes the same thing. It could be that we'll implant these items along with cataract surgery or stent surgery. If these developments come to pass, we'll be doing surgery on an even greater percentage of glaucoma patients.

Glaucoma threatens the sight of around 60 million people in the world, with 3 million of those in the United States. As 10,000 Baby Boomers are joining the ranks of Medicare every day, this disease will become more prevalent. In the past, a large number of these patients would have been destined for low or no vision, but it's now possible and economically feasible to prevent that fate for most of these patients. OSM