What is MIGS Glaucoma Surgery?

A novel technique called microinvasive glaucoma surgery (MIGS) aims to lower the risks connected with conventional glaucoma surgery. As opposed to standard glaucoma surgery, MIGS involves smaller incisions in the eye, precise lasers, and minuscule implants, all of which promote quicker healing and visual recovery.

When a patient has both visually significant cataracts and glaucoma, some MIGS operations are done as an independent procedure, whereas others are done during cataract surgery.

Although MIGS is a promising new treatment option for certain individuals with glaucoma, it does require a skilled glaucoma surgeon because this area is always developing and improving. When patients consider the advantages and disadvantages of various alternatives, they must consult with a glaucoma surgeon who is knowledgeable about all of them.

Scientists and ophthalmic researchers have long looked for new surgical treatment methods that can reduce intraocular pressure (IOP) quickly and effectively while maintaining a safety profile and utilizing ab-interno techniques that cause less tissue stress and have a quicker recovery time. These operations are referred to as minimally invasive or microinvasive glaucoma surgery (MIGS).

MIGS function by ciliary body ablation, uveoscleral outflow, trabecular meshwork bypass, enhanced aqueous outflow through Schlemm’s canal, and aqueous shunt through subconjunctival space.

With little tissue damage, a good post-operative recovery, and increased patient satisfaction, MIGS has completely changed the treatment of glaucoma. With encouraging outcomes, the MIGS choices have opened up a plethora of new possibilities for glaucoma doctors. The ability to combine MIGS with phacoemulsification to shorten surgery times is another benefit. To improve patient care, this activity addresses the numerous MIGS choices that are now available, as well as their design, effectiveness, insertion technique, and safety profile.

What’s so great about MIGS?

Major operations are required for standard glaucoma procedures like as trabeculectomy and ExPRESS shunts, which are external tube shunts like the Ahmed and Baerveldt types. They have a lengthy list of possible side effects, even though they are frequently successful in reducing ocular pressure and stopping the progression of glaucoma.

To lessen some of the difficulties associated with the majority of routine glaucoma procedures, the MIGS series of operations was established recently.

Microscopic instruments and small incisions are used in MIGS operations. They lessen the likelihood of problems, but in exchange for greater safety, they also give up some efficacy.

MIGS Categories

The operations within the MIGS group are classified into many categories:

• Trabeculectomy in miniature form
• Trabecular bypass techniques
• Suprachoroidal or entirely internal shunts
• Versions of laser photocoagulation that are less invasive.

Classification of Minimally Invasive Glaucoma Surgery (MIGS)

There are four primary methods that MIGS uses to lower IOP.

1. Increasing Schlemm Canal and Trabecular Meshwork Aqueous Outflow
2. The Stent
3. Hydrous Stent Injection
4. iStent Micro-Bypass Trabecular Stent

The smallest implanted instrument authorized for use within the human body is the iStent. The device is made of titanium and is inserted into the front of the eye at two distinct locations to provide two bypasses that improve the outflow of ocular fluid via the natural drainage system of the eye. Usually, the iStent is implanted at the same time as cataract surgery. At 23 months, most patients in the next-generation iStent Inject clinical trials were drug-free. Because the stent is composed of titanium, you may have MRI examinations done without running the danger of getting a metal implant.

Removal of Tissue

GATT stands for gonioscopy-assisted transluminal trabeculotomy.

These include:

• Dual-bladed goniotomy Kahook
• System Trabectome TRAB 360
• Laser trabeculectomy with excimer

For instance, the Trabectome, an electrocautery device authorized by the FDA in 2006, removes a portion of the meshwork that is a part of your eye’s natural drainage system for intraocular fluid. This operation increases your eye’s natural outflow channel, which lowers internal eye pressure by making a wider opening in the meshwork.

By way of Schlemm Canal

Ab Interno canaloplasty (ABiC) with the iTrack microcatheter system and the VISCO360 device

Two methods are used by the iTrack to restore the eye’s natural drainage system: First, a channel through the obstructed natural drainage canal (called Schlemm’s canal) of the eye is bored using a micro-catheter. After the material has been removed from the canal, a viscoelastic gel is injected into it and expands, making the canal diameter two to three times larger than it was before. Reduced ocular pressure and increased fluid outflow are the overall effects.

Greater Outflow of Uveoscleral Fluid via Suprachoroidal Space

CyPass micro-stent

They were initially used in 2016 and received FDA approval for the treatment of glaucoma. The stent is 6.35 mm by 510 um and is made of polyamide. It is flexible, fenestrated, and has a lumen of 300 um. This comes pre-loaded with a guidewire that verifies the sclera’s form to facilitate dissection and insertion between the suprachoroidal space and anterior chamber. The gadget was taken off the market in 2018 because it causes a greater rate of endothelial cell death.

Shunt’s through Subconjunctival Space

Implant Xen

This is a stent, the size of an eyelash, constructed of a soft gel substance. Without making an incision in the conjunctiva, it is inserted through the eyewall (the transparent membrane protecting the white of your eye). It is intended to remain in your eye indefinitely. To redirect extra ocular fluid from within your eye to a region immediately under the conjunctiva, or the transparent outer membrane covering the white of your eye, the XEN stent is positioned in the front of your eye.

Ablation of the Ciliary Process with a Decrease in Aqueous Outflow

Endocyclophotocoagulation

Endocyclophotocoagulation, sometimes referred to as ECP, uses a tiny camera inserted into the eye to see the ciliary body cells, which are the cells responsible for creating ocular fluid. After that, a highly focused laser beam is applied to these cells to reduce their activity in producing fluid, which lowers intraocular pressure. Patients with open-angle or closed-angle glaucoma can benefit from ECP, which takes around five minutes for each eye.

The apparatus consists of a diode laser probe unit. Using a video camera imaging system, helium-neon laser, and 175 W xenon light, the wave energy is released at a wavelength of 810 nm. The signals are sent by a fiber optic system inside the probe. The probe can be straight or curved, and it can be introduced through a transparent corneal incision. The endoscopic vision is made possible by the video display, and the surgeon can use the foot pedal to shoot the laser. The laser power is calibrated to observe blanching, ranging from 0.2 to 0.25 watts. A 200–300 degree angle is handled at a time.

What is the trabecular meshwork?

The spongy tissue that is situated close to the cornea and allows aqueous fluid to exit the eye is called the trabecular meshwork. Eighty to ninety percent of aqueous humor enters circulation through the trabecular meshwork and its related structures, which are located at the drainage angle. Scientists and ophthalmologists agree that the area of the trabecular meshwork that is most resistant to aqueous humor outflow is a specific portion of it. The ocular pressure will progressively rise in the presence of greater outflow resistance.

Various MIGS methods of action

IOP is lowered by minimally invasive glaucoma surgery through changes to the dynamics of the aqueous humor. In MIGS, the trabecular meshwork can be omitted. By employing a stent, the backup of aqueous outflow is avoided. By facilitating direct aqueous passage from the anterior chamber to Schlemm’s canal, the stent lowers intraocular pressure.

Goniotomy or trabeculectomy is the second method to get over the resistance of the trabecular meshwork. Better aqueous drainage through Schlemm’s canal is made possible by surgically altering tissue by incision or excision. Another strategy is to use viscoelastic dilating of the Schlemm canal to increase the natural physiological aqueous outflow.

The uveoscleral outflow is increased as the following MIGS approach. It is possible to implant a microstent in the suprachoroidal region. If this isn’t feasible, a little incisional ab interno technique can be used to circumvent aqueous and enter the subconjunctival area.

The last method uses ciliary body ablation to decrease the amount of fluid produced by ciliary processes. Endocyclophotocoagulation is the method used to do this, in which the ciliary body is ablated by inserting an endoscopic laser via a transparent corneal incision.

When It’s Best to Use MIGS?

The idea of employing MIGS as the initial surgical intervention in the treatment of glaucoma is a relatively novel one.

In the last ten years, MIGS has become more popular as a minimally invasive surgical technique for lowering intraocular pressure. Nonetheless, trabeculectomy has been the primary surgical procedure used throughout the previous 50 years.

According to some studies, MIGS is not a suitable substitute for traditional operations such as trabeculectomies. They think MIGS won’t be able to remove fluid from the eye as well over the long haul. On the other hand, trabeculectomies have shown to be long-lasting, safe, successful, and reasonably priced operations.

Traditional glaucoma surgery opponents claim that the procedures are frequently fraught with problems and that the outcomes are not always consistent. Different outcomes may be obtained in each eye by the same clinician using the same procedure on the same patient.

MIGS proponents think they are adequate and effective replacements for more invasive glaucoma operations. According to patient-centered care, the majority of patients favor the least intrusive procedures that are offered. MIGS provides minimum post-operative care, a brief recovery period, little risk, and a brief hospital stay. 

Summary

Better safety appears to be possible with several novel glaucoma surgical techniques. Like with any new surgery, more research and time will be needed to determine which methods would be most beneficial in the long run for glaucoma patients.

FAQ’s

How long does it take to recover from MIGS surgery?

You can easily get back to work and get back to your regular routines. Throughout your recuperation, you will need follow-up visits where you have intraocular pressure checked. The recuperation period is between one to four weeks, as opposed to two to three months for conventional glaucoma surgery.

Which glaucoma procedure has the highest rate of success?

About 7 out of 10 patients can have their ocular pressure lowered with a trabeculectomy, according to research. Those without a history of eye trauma or previous eye surgery may find it most effective.

How painful is surgery for glaucoma?

Local anesthetic usually prevents discomfort during surgery for most patients. ALT and LPI may cause mild burning or stinging. Some patients say that these treatments cause them a little discomfort. Compared to laser treatments, incisional glaucoma operations typically result in more pain following the procedure.

References

Gurnani, B. (2023, June 20). Minimally Invasive Glaucoma Surgery. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK582156/

MIGS for Glaucoma: The Best Surgical Option in 2022? | NVISION. (2023, August 30). NVISION Eye Centers. https://www.nvisioncenters.com/glaucoma/migs-surgery/

The Eye’s Drainage System, the Trabecular Meshwork & Glaucoma | BrightFocus Foundation. (2021, July 7). https://www.brightfocus.org/glaucoma/article/glaucoma-and-importance-eyes-drainage-system#:~:text=What%20is%20the%20Trabecular%20Meshwork,flows%20out%20of%20the%20eye.

Minimally Invasive Glaucoma Surgery (MIGS). (n.d.). Assil Gaur Eye Institute. https://assileye.com/library/minimally-invasive-glaucoma-surgery-migs

Stamper, R. L. (2022, December 21). What is MIGS? | glaucoma.org. glaucoma.org. https://glaucoma.org/what-is-migs/

Minimally Invasive Glaucoma Surgery (MIGS) | Stiles Eyecare Excellence. (2019, August 19). Stiles Eyecare Excellence. https://www.stileseye.com/glaucoma/minimally-invasive-glaucoma-surgery-migs/