Comparing MIGS Procedures
Understanding Minimally Invasive Glaucoma Surgery
MIGS stands for minimally invasive glaucoma surgery. It is a group of procedures that use tiny devices to lower eye pressure. These devices create new paths for fluid to drain out of the eye. MIGS fills the gap between eye drops and larger, more involved surgeries like a full filtering procedure.
Older glaucoma surgeries cut through more tissue and need longer healing times. MIGS uses small tools placed through the inside of the eye. This means less tissue damage, a faster return to daily life, and fewer office visits after surgery. The risk of serious problems is also lower with MIGS.
MIGS works best for people with mild to moderate open-angle glaucoma. It is a good choice when eye drops are not enough on their own. Many MIGS devices are placed at the same time as cataract surgery. People with more advanced glaucoma may still need a larger filtering procedure to reach their pressure goal.
MIGS devices are grouped by the path they use to drain fluid. The three main types are:
- Trabecular bypass stents, which push fluid through the natural drain tissue into the outflow canal
- Canal scaffolding devices, which prop open part of the outflow canal so it drains better
- Gel stents for bleb-based filtration, which move fluid from the front of the eye to a pocket under the outer layer of the eye
Trabecular Bypass Stents
A trabecular bypass stent is a tiny tube placed through the drain tissue at the front of the eye. It allows fluid to flow straight into the outflow canal. This skips the clogged meshwork that slows drainage in glaucoma. The stent is placed through the same small cut used for cataract surgery.
Studies show that these stents lower eye pressure when added to cataract surgery. At 12 months, 72% of stent patients had eye pressure at or below 21 mmHg without drops, compared with 50% of those who had cataract surgery alone (AAO EyeWiki, 2024). The stent adds a clear benefit on top of what cataract removal does by itself.
Cataract removal alone lowers eye pressure for most people. That makes it hard to tell how much of the drop comes from the stent. Research suggests about two-thirds of the pressure drop in a combined case comes from removing the cataract, and about one-third comes from the MIGS device (AAO EyeWiki, 2024). Surgeons keep this in mind when planning each case.
Trabecular bypass stents work best when the rest of the drain system is still healthy. The collector channels and veins beyond the canal must be open for the stent to help. People with mild to moderate glaucoma and a wide, open angle on exam tend to do well. Those with scarring in the angle or blocked collector channels may not get enough benefit.
Canal Scaffolding Devices
Canal scaffolding devices are curved implants that sit inside the outflow canal. They hold a large section of the canal open so it does not collapse. One type of scaffolding device props open about 90 degrees of the canal (AAO EyeNet, 2024). This helps fluid drain through a wider area than a single-point bypass.
A major trial compared canal scaffolding plus cataract surgery to cataract surgery alone. At 24 months, 77% of patients in the scaffolding group had a clear drop in pressure without drops, versus 58% in the cataract-only group (AAO EyeNet, 2024). The extra drainage from the device made a real difference.
Data from everyday clinical use back up the trial findings. At three years, 67% of eyes met all success targets, and average pressure fell 26.5% from 18.9 mmHg to 13.9 mmHg (AAO EyeNet, 2024). These numbers show that the benefit holds up over time in typical patients.
Five-year data from the same major trial showed lasting results. Patients with the scaffolding device kept lower pressure, used fewer drops, needed fewer follow-up surgeries, and had less risk of lasting vision field loss (AAO EyeNet, 2024). These long-term results matter most for younger patients who will live with glaucoma for decades.
Not every eye is a good match for canal scaffolding. The canal must be wide enough to hold the device safely. Eyes with average or narrow canal width face a higher chance of the device shifting out of place (AAO EyeNet, 2024). Imaging and angle exams before surgery help the surgeon decide if the canal is the right size. People with other types of glaucoma, such as those caused by new blood vessel growth or swelling, are usually not good candidates.
Bleb-Based Gel Stent Filtration
Gel stent filtration is the strongest type of MIGS. A soft, flexible tube is placed from inside the eye to route fluid under the outer eye layer. This forms a small fluid pocket called a bleb, much like a traditional filtering surgery but through a much smaller device. One common gel stent is 6 mm long with a 45-micrometer opening (AAO EyeNet, 2024).
Long-term data show that gel stents keep pressure lower for years. Average pressure dropped from 19.1 mmHg before surgery to 14.9 mmHg at 36 months (AAO EyeNet, 2024). The main success rate was 66%, and the total success rate, counting eyes that needed extra steps, reached 90% (AAO EyeNet, 2024). These numbers rival those of larger filtering surgeries.
Cutting down on daily eye drops is a key goal of glaucoma surgery. Drops can irritate the eye surface and are easy to forget. After gel stent surgery, the average number of glaucoma drops fell from 2.1 before surgery to 0.2 after (AAO EyeNet, 2024). Most patients in this group were able to stop nearly all their drops.
Because a gel stent creates a bleb, it carries risks more like those of a larger filtering surgery. Common issues include bleeding during surgery (9.4%), blood in the front of the eye after surgery (5.6%), needling to open a scarred bleb (23.4%), and bleb scarring (21.4%) (AAO EyeNet, 2024). Close follow-up helps catch these issues early so the surgeon can act quickly.
Gel stents can be placed on their own, without cataract surgery at the same time. However, the status of the lens affects how well the device works. Success rates were higher in eyes that had already had cataract surgery (73%) than in eyes with a natural lens (53%) or eyes having both surgeries at once (55%) (AAO EyeNet, 2024). The surgeon uses this data to decide the best timing for each patient.
Choosing the Right Procedure
Each MIGS type offers a different level of pressure drop. Trabecular bypass stents give a mild, steady reduction that fits mild glaucoma. Canal scaffolding devices offer a moderate drop with strong data out to five years. Gel stent filtration gives the largest drop and can come close to what a full filtering surgery achieves. The right choice depends on how low the target pressure needs to be.
All three types of MIGS cut down on the number of daily eye drops. Bypass stents may allow patients to stop one or two drops. Canal scaffolding devices cut drop use over several years. Gel stents bring many patients close to using no drops at all. Fewer drops means less eye surface irritation and easier daily routines.
Most MIGS patients heal quickly. Bypass stents and canal scaffolding placed during cataract surgery follow the same recovery plan as cataract surgery alone. Patients can usually get back to normal tasks within days. Gel stent patients may need more follow-up visits because of bleb care, and some may need a needling procedure in the weeks after surgery.
After any MIGS procedure, call your eye doctor right away if you notice a sudden change in vision, sharp eye pain, new redness, or the feeling that something is in your eye. A sudden burst of floaters or flashes of light also needs prompt attention. Keep all follow-up visits so your doctor can check your pressure, look at the device, and adjust your drops if needed.
Common Questions About Glaucoma MIGS
Some MIGS devices, mainly gel stents, can be placed on their own. Bypass stents and canal scaffolding devices are most often placed during cataract surgery. Your eye doctor will look at your lens, your pressure level, and your overall eye health to decide if a standalone or combined approach is best.
MIGS devices are meant to stay in the eye for the long term. They are made from materials the body handles well. Studies going out five years or more show that these devices keep working and stay in place. Removal is rare but possible if a problem comes up.
Many patients cut back on or stop their drops after MIGS, but results vary. Some people still need one or more drops to keep pressure in a safe range. The type of MIGS and the stage of glaucoma both play a role. Your doctor will adjust your drops based on your pressure readings after surgery.
Most MIGS done along with needed cataract surgery are covered by medical plans. Standalone procedures may need separate approval. Check with your plan and ask the surgery team about any costs you may owe before your procedure date.
If pressure stays too high after MIGS, the doctor has other tools. Drops can be started again or changed. Laser treatments can be tried. In tough cases, a larger filtering surgery can still be done. A prior MIGS device does not block future surgical options.
There are no strict age cutoffs. MIGS is most common in adults over 40 with open-angle glaucoma. Younger people with certain types of glaucoma may also qualify. The doctor looks at each person's disease, eye shape, and health to make the call.
Schedule a Glaucoma Evaluation
If you have glaucoma or think your eye pressure may be high, an in-depth exam can help find the right next step. Contact our office to book a visit with a glaucoma specialist who can go over your options and build a care plan just for you.