Minimally Invasive Glaucoma Surgery (MIGS) Guide
What Is Minimally Invasive Glaucoma Surgery?
Minimally invasive glaucoma surgery, commonly known as MIGS, represents a significant advancement in how glaucoma is treated surgically. These procedures use microscopic devices and tiny incisions to lower intraocular pressure (IOP), the primary risk factor for glaucoma progression, while offering a gentler recovery than traditional surgical approaches. At Greenwich Ophthalmology Associates, our glaucoma specialists in the greater NY/CT region help patients understand whether MIGS may be an appropriate next step in their treatment plan. This guide covers the types of MIGS procedures available, how they work, and what you can expect as a patient considering this approach.
MIGS refers to a group of surgical procedures designed to reduce eye pressure through smaller, safer interventions than traditional glaucoma operations like trabeculectomy or tube shunt surgery.
Unlike conventional glaucoma surgeries that create larger openings to drain fluid from the eye, MIGS procedures use micro-sized devices and an ab interno approach, meaning the surgeon operates from inside the eye rather than through the outer surface. This internal approach reduces tissue disruption and lowers the risk of complications such as infection, prolonged inflammation, and dangerously low eye pressure (hypotony). Most MIGS procedures take only a few minutes to perform and can often be done at the same time as cataract surgery.
Glaucoma develops when the eye's natural drainage system cannot move aqueous humor, the clear fluid inside the eye, out efficiently, causing pressure to build. MIGS devices work by creating new pathways or improving existing ones so that fluid can drain more freely. Depending on the specific device, this may involve bypassing a clogged trabecular meshwork, opening a channel into the suprachoroidal space, or directing fluid beneath the conjunctiva (the clear membrane covering the white of the eye).
Traditional glaucoma surgeries like trabeculectomy can achieve very low eye pressure targets but carry higher complication rates and require more intensive postoperative care. MIGS procedures generally provide a moderate reduction in eye pressure with a much more favorable safety profile. For patients with mild to moderate glaucoma, MIGS often strikes the right balance between effectiveness and a faster, more comfortable recovery. You can explore these differences in greater detail in our resource on how MIGS compares to traditional glaucoma surgery.
How MIGS Procedures Are Performed
All MIGS procedures share certain features that set them apart from older surgical methods for glaucoma.
MIGS procedures are typically performed in an outpatient surgical center under topical or local anesthesia. You remain awake but comfortable throughout the procedure, which usually lasts between 5 and 20 minutes depending on the device being placed and whether it is being combined with another procedure such as cataract removal.
During MIGS, the surgeon uses a specialized microscope and a goniolens (a mirrored contact lens placed on the eye) to visualize the eye's internal drainage structures. The device is then inserted through a tiny corneal incision already created for cataract surgery or through its own micro-incision. Because no external incision through the conjunctiva is needed for most MIGS approaches, the eye's outer tissues remain intact for potential future procedures if needed.
You will receive numbing drops and possibly a mild sedative to keep you relaxed. After the procedure, a protective shield is placed over the eye. Most patients notice only mild discomfort, slight blurriness, or a gritty sensation in the first day or two. Your surgeon will prescribe anti-inflammatory and antibiotic eye drops to use during your recovery. Follow-up appointments are typically scheduled within the first week and again at one month to monitor your eye pressure and healing.
Types of MIGS Devices and Procedures
Several FDA-approved MIGS devices are available, and each targets a different part of the eye's drainage system to lower pressure.
The iStent, iStent inject W, and Hydrus Microstent are among the most widely used MIGS devices. These tiny implants are placed directly into the trabecular meshwork, the eye's natural drain, to create a bypass that allows aqueous humor to flow more easily into Schlemm's canal. These devices are approved for use alongside cataract surgery in patients with mild to moderate open-angle glaucoma. Clinical studies have shown they can reduce eye pressure by approximately 15 to 30 percent and decrease the number of glaucoma medications patients need.
The XEN Gel Stent takes a different approach by creating a drainage pathway from inside the eye to the subconjunctival space beneath the outer membrane of the eye. This mechanism is similar in concept to trabeculectomy but involves a much smaller, gel-based implant inserted through an ab interno approach. The XEN stent may be appropriate for patients with moderate to more advanced glaucoma and can be performed as a standalone procedure or combined with cataract surgery.
Procedures such as goniotomy and trabectome remove or cut away a portion of the trabecular meshwork rather than implanting a device. Gonioscopy-assisted transluminal trabeculotomy (GATT) is another technique that opens 360 degrees of the drainage canal. These tissue-based approaches can lower eye pressure effectively without leaving a permanent implant inside the eye. They may be offered as alternatives for patients who prefer a device-free option or for whom stent placement is not ideal.
Suprachoroidal MIGS devices direct fluid from the front of the eye into the suprachoroidal space, a natural potential space between the outer wall of the eye and the choroid. While the CyPass Micro-Stent was previously available for this approach, it was voluntarily recalled due to long-term endothelial cell safety concerns. Newer suprachoroidal devices continue to be developed and studied. Our glaucoma specialists stay current with the latest approved options to offer patients the safest and most effective choices. For a broader look at all available approaches, visit our overview of minimally invasive glaucoma surgery.
Who Is a Candidate for MIGS?
Not every glaucoma patient will benefit equally from MIGS, so a careful evaluation is essential to determine whether these procedures are the right fit.
MIGS is generally most effective for patients with mild to moderate open-angle glaucoma who need additional pressure lowering beyond what eye drops or laser treatments can achieve. Patients who have difficulty using or tolerating daily eye drops due to side effects, forgetfulness, or physical challenges with drop instillation are also strong candidates. Many patients are first introduced to MIGS when they are already planning cataract surgery, since several devices are approved for placement at the same time as lens replacement.
Patients with advanced glaucoma who need very low target pressures may require more aggressive procedures such as trabeculectomy or tube shunt implantation. Our glaucoma specialists evaluate each patient's disease severity, pressure goals, medication burden, and overall eye health to recommend the most appropriate glaucoma treatment approach. In some cases, MIGS can serve as a stepping-stone that delays or reduces the need for more invasive surgery later.
Before recommending MIGS, your doctor will perform a thorough glaucoma workup including eye pressure measurement, optic nerve assessment, visual field testing, and optical coherence tomography (OCT) imaging. These tests help establish a clear picture of your glaucoma severity and how it has changed over time. Understanding your complete surgical options and their associated risks allows you to make an informed decision alongside your care team.
Frequently Asked Questions
Most patients experience a measurable reduction in eye pressure within the first few weeks after surgery. Studies show that MIGS devices can lower pressure by 15 to 50 percent depending on the device and individual factors. Many patients are able to reduce the number of daily glaucoma drops they use, and some can stop drops entirely. Your specific outcome will depend on the type of device, the severity of your glaucoma, and how your eye responds to the implant.
While one of the goals of MIGS is to reduce medication burden, not all patients can discontinue their eye drops completely. Clinical data suggests that a meaningful percentage of patients are able to stop at least one medication after MIGS, and some become drop-free. Our glaucoma specialists will monitor your pressure closely after surgery and adjust your medication regimen as your healing progresses.
MIGS procedures carry a lower risk profile than traditional glaucoma surgery, but no surgical procedure is entirely without risk. Possible complications include temporary blood in the front of the eye (hyphema), mild inflammation, a transient spike or dip in eye pressure, and, rarely, device malposition. Serious complications such as infection or significant vision loss are uncommon. Your surgeon will discuss the specific risk profile of the recommended device before your procedure.
Recovery after MIGS is typically faster and more comfortable than after trabeculectomy or tube shunt surgery. Most patients return to normal daily activities within a few days, and visual recovery is often rapid since the procedure involves minimal tissue disruption. Traditional surgeries may require weeks of restricted activity and more frequent follow-up visits during the healing period.
Yes, many MIGS devices are specifically designed to be implanted during cataract surgery. Combining the two procedures allows patients to address both conditions in a single visit to the operating room, reducing overall recovery time and anesthesia exposure. The iStent, iStent inject W, and Hydrus Microstent are all FDA-approved for combined use with cataract removal. If you have both glaucoma and cataracts, this combined approach may be an efficient option to discuss with your care team.
If your current glaucoma treatment is not achieving your target eye pressure, if you are experiencing side effects from eye drops, or if you are considering cataract surgery and also have glaucoma, it may be a good time to discuss MIGS. Even if your glaucoma is well controlled, understanding your future surgical options can help you feel more prepared. Lifestyle factors such as caffeine intake and its effects on eye pressure are also worth discussing during your next appointment.
Explore Whether MIGS Is Right for You
Minimally invasive glaucoma surgery offers a gentler, effective path toward better eye pressure control for many patients living with glaucoma. At Greenwich Ophthalmology Associates, our fellowship-trained glaucoma specialists in the greater NY/CT region bring decades of combined experience evaluating and performing these advanced procedures. We are here to help you understand your options, weigh the benefits and risks, and find the approach that fits your vision goals and lifestyle. Schedule a consultation to learn whether MIGS may be an appropriate step in your glaucoma care.
We encourage you to bring your questions and concerns to your next appointment so we can develop a care plan that addresses your goals and lifestyle.
Learn More About Related Topics
To further your understanding, explore our resources on Enhance Your Vision With Minimally Invasive Glaucoma Surgery, Glaucoma Surgery Combined with Cataract Surgery, and MIGS and Traditional Glaucoma Surgery.
You may also find these pages helpful: Childhood and Congenital Glaucoma: A Guide for Parents, Glaucoma Eye Drops: Complete Medication Guide, and Glaucoma Laser Surgery.
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