MIGS Surgery (Minimally Invasive Glaucoma Surgery)
A family of small-incision procedures that improve the eye's natural drainage with a much faster recovery than traditional glaucoma surgery — often performed at the same time as cataract surgery.
What Is MIGS?
Minimally invasive glaucoma surgery (MIGS) refers to a family of small-incision procedures and devices designed to improve the eye's natural drainage with far less tissue disruption, faster recovery, and a better overall safety profile than traditional glaucoma surgery. Most MIGS procedures are performed through the same tiny incision used for cataract surgery, and several are specifically designed to be combined with it. Below, we describe the four devices we use most, in the order they're typically considered, followed by a note on a few other options.
Explore Each MIGS Procedure in Detail
Each of the main MIGS procedures we perform has its own dedicated page explaining the anatomy of the surgery, which glaucoma it treats, and its specific benefits and risks.
iStent (Trabecular Bypass)
A microscopic titanium stent that bypasses the trabecular meshwork into Schlemm's canal — typically combined with cataract surgery.
Learn More →Goniotomy (KDB, GATT)
Opens or removes the diseased trabecular meshwork — using the Kahook Dual Blade, GATT, OMNI, or Trabectome — leaving no implant behind.
Learn More →Canaloplasty (OMNI, iTrack)
Reopens and stretches Schlemm's canal 360° with the OMNI system or iTrack microcatheter to restore natural drainage.
Learn More →XEN Gel Stent
A soft implant that creates new subconjunctival drainage to reach lower target pressures — a bridge between MIGS and filtering surgery.
Learn More →iStent
The iStent (and its newer version, iStent inject W) is a tiny, heparin-coated titanium device implanted directly through the trabecular meshwork into Schlemm's canal, creating a permanent bypass around the eye's main point of resistance to outflow. It is one of the smallest medical devices ever approved for implantation in the human body. In the United States, iStent is FDA-approved specifically for use at the time of cataract surgery in patients with mild-to-moderate open-angle glaucoma, and the newer inject W version places two stents for a broader area of bypass.
Ab-Interno Canaloplasty
Ab-interno canaloplasty uses a fine microcatheter (systems such as OMNI or iTrack) inserted through a small incision to thread around and viscodilate all 360 degrees of Schlemm's canal — gently stretching the canal open with a viscous fluid to reduce resistance to outflow along its entire circumference, rather than at a single point. This is frequently combined with a trabeculotomy (cutting open a strip of trabecular meshwork) performed with the same device, and can be done alone or combined with cataract surgery.
Hydrus Microstent
The Hydrus Microstent is a small, flexible, nitinol (a springy, shape-memory metal) scaffold that is inserted into Schlemm's canal, where it spans roughly 90 degrees of the canal's circumference — both dilating that segment of the canal and bypassing the trabecular meshwork at the point of insertion. It is approved for use either alone or combined with cataract surgery, and clinical trial data (the HORIZON trial) demonstrated sustained pressure reduction and reduced medication use through multiple years of follow-up.
Xen Gel Stent
The Xen Gel Stent takes a different approach: a soft, flexible gelatin tube is placed through a tiny incision to create a new drainage channel from inside the eye directly to the space under the conjunctiva (the clear membrane covering the white of the eye), forming a filtering bleb similar in concept to a traditional trabeculectomy, but through a far less invasive, ab-interno approach. Because it creates a bleb, Xen tends to achieve a lower target pressure than the other MIGS devices described here, though it also carries some of the bleb-related monitoring considerations seen with trabeculectomy, just to a lesser degree. It can be performed alone or combined with cataract surgery.
Standalone vs. Combined With Cataract Surgery
Many patients considering MIGS also have a visually significant cataract, and combining MIGS with cataract removal in a single surgery is extremely common — it adds relatively little time or risk to the cataract procedure itself, while addressing both conditions at once. That said, several MIGS devices, including Hydrus and Xen, are also approved for standalone use in patients who don't yet need cataract surgery, whenever a lower-risk surgical option makes sense before considering trabeculectomy or tube shunt surgery.
Risks & Side Effects
- ✓Temporary blood reflux into the front chamber of the eye (hyphema), most common with canaloplasty/trabeculotomy techniques and typically resolving on its own
- ✓Transient eye pressure spikes in the early post-operative period
- ✓Device malposition or, rarely, need for repositioning or removal
- ✓With Xen specifically, bleb-related considerations similar to (though generally milder than) trabeculectomy, including the possibility of needing a bleb needling procedure
- ✓As with any eye surgery, a small risk of infection or inflammation
Other MIGS Options
A few additional MIGS techniques are worth knowing about: the Trabectome uses electrocautery to ablate a strip of trabecular meshwork from inside the eye; the Kahook Dual Blade is a specialized goniotomy blade that excises a strip of meshwork with two parallel blades; and gonioscopy-assisted transluminal trabeculotomy (GATT) uses a suture or catheter to open the meshwork around a larger portion of the angle's circumference, similar in spirit to ab-interno canaloplasty. Each has its own ideal patient profile, and we're glad to discuss whether any of these fits your situation.
MIGS is generally reserved for mild-to-moderate glaucoma, or as an early step before considering more IOP-lowering (but higher-risk) options. For more advanced or uncontrolled glaucoma, see our Trabeculectomy and Tube Shunt Surgery pages.
Frequently Asked Questions
Can MIGS be done on its own, without cataract surgery?
Yes. Several MIGS devices, including Hydrus and Xen, are approved for standalone use in phakic (non-cataract) eyes. Others, like iStent, are FDA-approved specifically in combination with cataract surgery in the United States.
How does MIGS compare to trabeculectomy or tube shunt surgery?
MIGS generally lowers pressure less dramatically than trabeculectomy or tube shunt surgery, but with a substantially better safety profile and faster recovery, making it a good fit for mild-to-moderate glaucoma. More advanced or uncontrolled glaucoma often still needs traditional surgery — see our Trabeculectomy and Tube Shunt Surgery pages.
Will MIGS eliminate my need for eye drops?
Many patients reduce their drop burden after MIGS, and some eliminate it entirely, but this isn't guaranteed for everyone. Your specialist will set realistic expectations based on your specific glaucoma severity and the device used.
Are there other MIGS options besides these four?
Yes. Other devices include the Trabectome, Kahook Dual Blade, and gonioscopy-assisted transluminal trabeculotomy (GATT), which all work by directly opening or removing a strip of trabecular meshwork. We're happy to discuss whether any of these are a good fit for your specific situation.
See a glaucoma specialist. Dr. Robert Gunzenhauser is Harvard-educated and UCLA fellowship-trained in glaucoma, providing expert diagnosis and treatment for MIGS Surgery at Inland Glaucoma Center in Upland, CA.