Minimally-invasive glaucoma surgery, or MIGS, refers to a type of glaucoma treatment that involves five main principles, according to the American Academy of Ophthalmology’s EyeWiki:

1. Highly safe, with a low risk of serious complications
2. No major alterations to the eye’s anatomy
3. Performed “ab interno” (to decrease intraocular pressure, or IOP, by increasing aqueous outflow)
4. High level of efficacy (significant lowering of IOP)
5. Quick recovery (minimal downtime) for patients

There are multiple MIGS procedures available, so it’s important to understand what this type of surgery generally entails and the differences between each procedure.* While there are clearly defined benefits to this type of surgery, clinicians still do not have enough data on the long-term safety and effectiveness of MIGS. 

Invasive vs. minimally invasive surgeries

Glaucoma surgery is performed to lower IOP by improving the outflow of eye fluid. Common surgeries for glaucoma patients include trabeculectomy or tube shunt surgeries, which are performed on the outside of the eye. These surgeries are especially effective for people with advanced glaucoma who need to significantly lower their IOP.

MIGS are different in that they are performed from inside of the eye. Types of MIGS include Trabectome, iStent, and Xen. To be considered minimally invasive, these surgeries must avoid:

• Surgical manipulation of the sclera, or the thick white wall of the eye. Trabeculectomy involves extensive cutting of the sclera, including trabeculectomy modified with the Ex-PRESS shunt surgeries.
• Major manipulation of the conjunctiva, or the transparent outermost layer of the eye. Trabeculectomy and tube shunt procedures involve extensive cutting of the conjunctiva.

Types of MIGS devices and procedures

The following MIGS procedures are currently approved by the U.S. Food and Drug Administration (FDA), all of which are known to be safer than traditional trabeculectomy or tube shunt surgeries. 

Trabectome

The Trabectome, or trabeculectomy ab-interno, is performed on the inside of the eye. This procedure was approved by the FDA in 2006. It involves an electrocautery device that removes part of the trabecular meshwork, which opens up the outflow channels of the eye and, thus, lowers your IOP. 

The most common complication of this procedure is the presence of blood in the front of the eye after the procedure is performed. Typically, this is limited and clears quickly, but in some cases, scarring can occur. A Trabectome can be performed with cataract surgery. 

iStent

The iStent is a titanium device that is implanted from inside of the eye into the trabecular meshwork. This allows the trabecular meshwork to be bypassed so that aqueous humor, or eye fluid, can drain, or flow, with ease. 

iStents are usually implanted during cataract surgery, and in some cases, more than one iStent is implanted. The iStent has a higher safety profile, but it doesn’t have the ability to as significantly lower IOP as a traditional trabeculectomy. 

Xen

Xen is a MIGS device that uses a gel microstent to create a trabeculectomy inside of the eye. No incisions need to be made in the conjunctiva; the stent is placed through the eyewall and under the conjunctiva using a less-invasive approach. Similar to a traditional trabeculectomy, anti-scarring medications are often prescribed with Xen. This type of MIGS can require more post-operative procedures because scarring does occur.

Discontinued procedures and new clinical trials

A micro-stent called CyPass® was voluntarily removed from the market by its manufacturer in 2018. There are, however, other MIGS devices and procedures that are currently being tested in clinical trials, such as the MINIject by iSTAR Medical. 

The MINIject is a biocompatible implant that is made of “a soft and flexible, medical-grade silicone with a micro-porous, multi-channel geometry” that “enhances natural eye drainage,” “flexibly conforms to the eye anatomy,” “allows surrounding tissues to bio-integrate into the material,” and “enables a natural flow speed, reducing the incidence of fibrosis and minimising scarring,” according to an April 2020 press release.

Is a MIGS right for you?

MIGS procedures are believed to be best suited for people with mild-to-moderate glaucoma. In contrast, traditional surgeries may be considered for those with advanced glaucoma. 

Other instances when MIGS may be appropriate include:

• When glaucoma patients are intolerant of, or noncompliant with, IOP-lowering drops
• When glaucoma patients do not require a very low target IOP
• For those who are also undergoing cataract surgery

When looking for the best surgeon and best procedure for your eye health needs, be sure to ask your eye doctor the following questions at your appointment:

• How many MIGS procedures have you performed and what types, if any?
• Do you have a financial interest in a company that produces a MIGS device? Do you have any other conflicts of interest?
• Would you undergo this procedure or recommend a family member to undergo it?

*Ou, Y. (2020, Aug. 20). Glaucoma Surgery Series: Minimally-Invasive Glaucoma Surgeries (MIGS). BrightFocus Foundation. https://www.brightfocus.org/glaucoma/article/glaucoma-surgery-series-minimally-invasive-glaucoma-surgeries-migs

Any sources from outside of Prevent Blindness do not imply an endorsement from Prevent Blindness. The contents of the material used are the responsibility of the authoring organization, Responsum Health.