Glaucoma Treatments – Surgeries and Procedures
Surgeries and Procedures for Moderate and Advanced Glaucoma
Glaucoma is a group of diseases that can damage your eye’s optic nerve and result in vision loss and blindness. When medications are not effective enough in lowering the pressure in the eye or have intolerable side effects, surgery may be the next best option. Surgery is another way to treat glaucoma by facilitating aqueous fluid drainage. There are now many good treatment options available to protect the vision. Which option is most appropriate for you will depend on the severity of your glaucoma and the comfort of your surgeon with the available glaucoma treatment options.
Glaucoma Surgery Categories
There are a number of different types of surgeries and techniques, which can be split into (roughly) three using this categorical criteria.
- Non-invasive (i.e. laser)
- Minimally invasive – a whole new type of glaucoma surgery (i.e. Canaloplasty)
- Penetrating or the standard glaucoma surgery (i.e. Trabeculectomy and glaucoma drainage devices)
Clearly, of those three most people would prefer to avoid that last one.
We can also think of glaucoma surgery in terms of a MNEMONIC – SEA
- Shunts, which is essentially creating a non-physiologic pathway from the anterior chamber into usually subconjuctival space but it could be something else too.
- Enhance, which is to take the natural pathway of anterior chamber through the trabecular meshwork into Schlemm’s canal and then out the collector channel system into the venous system.
- Ablate. Destroy.
There are now multiple glaucoma treatment options that can be performed to lower intraocular pressure and prevent further vision loss.
Currently Available Glaucoma Surgical Treatments
Laser Trabeculoplasty (Non-Invasive – Enhance)
Argon Laser Trabeculoplasty
It works well for open-angle glaucoma. It can be performed in one to two sessions but the problem is it does still result in microscopic scars and also may limit future surgeries. So surgeries that involved opening up that Schlemm’s canal, can actually be problematic because the scars essentially seal the canal, so surgery such as Canaloplasty and potentially some of the newer surgeries that are not yet available could be limited by Argon Laser Trabeculoplasty.
Selective Laser Trabeculoplasty
More recently in the 1990s, Doctor Latina developed Selective Laser Trabeculoplasty. It’s called Selective Laser Trabeculoplasty because the laser is selectively absorbed by pigment. So, the melanin granules in the trabecular meshwork. It only uses 1 percent of the energy of Argon Laser Trabeculoplasty. Selective Laser Trabeculoplasty doesn’t cause any coagulative damage, it doesn’t limit future surgeries. And because it doesn’t cause any Damage it can actually be repeated. So it works about seventy percent of the time. Works about as well as a drop, which is also about as well as Argon Laser Trabeculoplasty work so it’s not really any better in terms of how of effective it is but it’s its repeatable and it doesn’t close future doors.
Micropulse Laser Trabeculoplasty
Micropulse Laser Trabeculoplasty (MLT) essentially segments the pulses into these tiny little super-fast pulses and by doing so you don’t get the Heat. You don’t get the increase in temperature. So you don’t get coagulative damage and there’s less damage in scarring but you get the same kind of result as you would with SLT or Argon Laser Trabeculoplasty (at least according to the company documents) but there just aren’t as many good studies on this.
Trabeculectomy Glaucoma Surgery (Penetrating – Shunt)
Trabeculectomy is traditionally offered to patients who have failed drops, failed SLT, and they’re advancing their glaucoma. Traditionally the glaucoma has to be pretty severe – at least moderate to severe. Trabeculectomy isn’t offered to somebody with mild glaucoma or just ocular hypertension because Trabeculectomy – there’s no other way to say it, pretty barbaric: You’re creating a fistula in the eye.
The oldest of modern glaucoma surgeries, trabeculectomy rapidly decreases intraocular pressure by punching a hole in the eye . A flap is left in place in order to control the amount of fluid that percolates under the thin surface layer of tissue (called the “bleb”).
Due to the invasive nature of the procedure, there is the danger of severe bleeding, bleb failure due to sudden decompression post operatively as well as formation of scar tissue. Moreover, trabeculectomy places the eye at increased lifetime risk for infection.
Glaucoma Drainage Devices (Penetrating – Shunt)
Also known as aqueous shunts or drainage implants, these plate-shaped devices must be sutured onto the surface of the eye beneath the conjunctiva. The hollow tube which connects to the plate is either inserted through the cornea or sclera at the time of initial surgery or at a later date. Once the tube has been properly inserted these implants function by draining fluid from the inside of the eye into a reservoir around the plate and underneath the conjunctiva.
Placement of a glaucoma drainage device is the preferred surgery in congenital glaucoma that fails to respond to goniotomy or trabeculotomy, glaucoma that has resulted from injuries to the eye, and neovascular glaucoma. They are also used to treat glaucoma patients who have no lens in the eye (this is called ”aphakia”) and those who have undergone corneal transplant surgery. Its most common indication, however, is in patients who have failed other glaucoma surgeries such as trabeculectomy and canaloplasty.
Endoscopic Cyclophotocoagulation (Minimally Invasive – Ablate)
This procedure uses a small laser probe to heat up and destroy the ciliary body (the tissue that produces fluid in the eye). As with Trabectome, the IOP after ECP is generally in the upper teens. Although a fast procedure, it does result in significant inflammation after surgery which can be both uncomfortable for the patient as well as temporarily blurring the vision.
The real issue with ECP is that there aren’t that many studies out so we really don’t know how well it works. It seems to be pretty effective for mild to moderate glaucoma.
[Video Credit: EndoOptiks Animation of Basic ECP (Endoscopic Cyclophotocoagulation) [Internet]. 2015 [cited 2016 Feb 4]. Available from: https://youtu.be/CET-5kyofWo]
Trabectome (Minimally Invasive – Ablate/Enhance)
This procedure uses a small instrument that opens a section of the trabecular meshwork (the small filter inside the eye that can get “clogged” resulting in high IOP). Once the meshwork is open the fluid in the eye should be able to get to the “collector channels” thereby reducing the IOP. In general, this procedure (when combined with cataract surgery) can lower the IOP into the high teens. Often there is bleeding inside of the eye that can blur vision after Trabectome but it generally resolves in a week or two.
This is another one of those procedures that is generally only done with cataract surgery or after cataract surgery. The major downside of this surgery is that once it is done other glaucoma surgeries such as Canaloplasty and placement of an iStent cannot be done. In other words, this procedure “closes doors” on the ability to use other promising glaucoma treatments.
iStent Trabecular Micro-Bypass Device (Minimally Invasive – Enhance)
The iStent is the first FDA approved “trabecular microbypass device.” It is a 1.0mm long snorkel-like device made out of medical grade titanium. It is, in fact, the smallest medical device approved for implantation in the human body. Weighing only 0.000002 ounces and with a price tag of roughly $1,000 this makes it one of the most valuable items on Earth by weight. An ounce of these little devices would set you back roughly a half billion dollars!
The long end of the snorkel is tapered. Using a specially designed inserter, the surgeon presses the tapered end through the trabecular meshwork and lodges it into the canal of Schlemm. This allows aqueous fluid to flow out of the anterior chamber directly into Schlemm’s canal.
[Video Credit: Ahmed I. iStent Trabecular MicroBypass Implantation Ike Ahmed [Internet]. 2013 [cited 2016 Feb 4]. Available from: https://youtu.be/ocTZJYifvQ0]
If you happen to have ocular hypertension or mild glaucoma that is well-controlled on one or two drops and your cataract is ready to be surgically removed and your insurance covers placement of an iStent or you happen to be obscenely wealthy and just like the idea of having a piece of microscopic titanium eye jewelry then this might be a reasonable option for you to consider.
If, on the other hand, your glaucoma is moderate or severe, poorly controlled, your insurance doesn’t cover placement of an iStent, or you are likely to need additional glaucoma surgery in the future, then the iStent is likely to disappoint.
Canaloplasty (Minimally Invasive – Enhance)
Canaloplasty is a non-penetrating (wall of the eye is not cut all the way through) glaucoma surgery developed by Dr. Robert Stegmann in 2008 with origins dating as far back 1968! It is an advanced surgical treatment for glaucoma which uses the world’s smallest microcatheter to dilate and open the eye’s natural drainage system – reestablishing the normal flow of fluid out of the eye. Because it is safer than the more traditional glaucoma procedures and more effective than the other procedures listed already, it occupies the “sweet spot” of surgical glaucoma treatments in that it is both low risk and effective. After Canaloplasty the IOP can be reduced by up to 40% resulting in an IOP in the low-to-mid teens for most patients. Additionally, many patients who have canaloplasty are off all of their glaucoma medications after surgery!
Ab Externo Canaloplasty
Canaloplasty uses a micro-catheter to open the eye’s natural drainage system (“Schlemm’s canal”). This canal is then opened using a sterile, gel-like material (“viscoelastic”). The iTrack® micro-catheter is then removed while a suture is threaded through Schlemm’s canal. The suture is then tied down resulting in tension on the inner wall of the canal – just as you might pull on the strings of a “hoodie” to close the hood over your face. The suture placed in the eye’s drainage canal can keep the canal stretched open for years. Once this canal is opened, the eye’s fluid can exit through a more natural process allowing the pressure in the eye to drop to a more normal level.
- It uses the eye’s natural drainage system
- It is a “non-penetrating” procedure that does not create a permanent fistula in the wall of the eye
- It does not require a bleb (a blister-like fluid collection)
- Provides long-term reduction in IOP (see three year results below)
- Reduces the need for medications to keep the IOP controlled
- Is a good option for those patients who are not yet ready for more trabeculectomy or tube shunts
- Is safer than traditional glaucoma surgeries (Canaloplasty vs Trabeculectomy)
Ab Interno Canaloplasty
Canaloplasty uses an iTrack™ microcatheter to open the eye’s natural drainage system (“Schlemm’s canal”). Whereas, with traditional Canaloplasty, the Micro-catheter is inserted from an external approach: cutting through the conjuctiva and sclera, with Ab-Interno Canaloplasty, the Micro-catheter is inserted from an internal approach: through either a clear corneal or a limbal micro-incision, then through a small opening in the Trabecular Meshwork, and into the Schlemm’s canal. With Ab-Interno, the eye tissue is preserved and not cut – no more flaps!
- Similar benefits as traditional canaloplasty
- Similar IOP-lowering as tried and true traditional Canaloplasty.
- Restoration of the eye’s natural drainage channels.
- No permanent placement of foreign body – prolene suture, stents or implants, in the eye!
- Future surgery is not compromised
- Easier and quicker 15 minutes Procedure!
- Preserves tissue. No deep cuts or creation of flaps needed!
- Potentially offer better clinical outcomes than any other currently available MIGS procedure.