MIGS Vs. Traditional Glaucoma Surgery

Minimally invasive glaucoma surgery refers to a group of procedures that use microscale devices or tiny incisions inside the eye to improve the natural drainage of fluid. Because these procedures work through the same small incision used during cataract surgery, they cause less tissue disruption and carry a lower risk of serious complications. MIGS is generally best suited for patients with mild to moderate open-angle glaucoma who need a modest reduction in eye pressure or who want to reduce their dependence on daily eye drops. One of the major advantages of MIGS is that many devices can be implanted during cataract surgery with little to no additional surgical time or risk, allowing patients to address both conditions in a single visit.

Devices such as the iStent inject and the Hydrus Microstent are placed directly into Schlemm's canal, the eye's natural drainage channel, to bypass the trabecular meshwork where fluid outflow is often restricted. These tiny implants restore a more normal drainage pathway and are frequently placed at the time of cataract surgery. Clinical studies have shown that the Hydrus may offer slightly greater pressure lowering and higher rates of drop-free glaucoma control compared to the iStent, though the differences are modest. Other MIGS techniques use instruments such as the Kahook Dual Blade or the OMNI Surgical System to remove or cut through the trabecular meshwork itself, allowing fluid direct access to Schlemm's canal without leaving a permanent implant in the eye.

The XEN Gel Stent works differently from other MIGS devices by creating a small drainage channel from inside the eye to the space beneath the conjunctiva, similar in concept to a trabeculectomy but through a much smaller approach. Because it drains fluid to the subconjunctival space, the XEN can achieve a greater pressure reduction than canal-based MIGS devices, making it an option for patients with moderate to advanced glaucoma. A minor follow-up procedure called needling is sometimes needed if the drainage bleb scars over time. The XEN bridges the gap between canal-based MIGS and traditional surgery, offering more filtration than a stent with less invasiveness than a full trabeculectomy.

Traditional glaucoma surgery includes procedures like trabeculectomy and tube shunt implantation. These operations create entirely new pathways for fluid to leave the eye, which typically results in a greater and more sustained drop in eye pressure. A trabeculectomy creates a small flap in the sclera that allows excess fluid to drain into a filtering bleb beneath the conjunctiva, while tube shunt surgery involves placing a small silicone tube connected to a plate on the outside of the eye. Cyclophotocoagulation (CPC) is another option that uses laser energy to reduce fluid production inside the eye and is typically reserved for advanced or refractory glaucoma. Because of their stronger pressure-lowering effect, traditional surgeries are often recommended when glaucoma is more advanced, progressing quickly, or not adequately controlled by less invasive treatments.