|What are Minimally Invasive Glaucoma Surgeries (MIGS)?
By Anita Campbell, MD
Grene Vision Group
When patients are experiencing symptoms from visually significant cataracts, it is an excellent time to address both the cataract and glaucoma conditions simultaneously. If a patient is on one or more eye medications for glaucoma, a glaucoma procedure should be performed at the time of cataract surgery. There are options of traditional glaucoma surgeries or the newer glaucoma surgeries called Minimally Invasive Glaucoma Surgery (MIGS).
The goal of glaucoma surgery is to lower intraocular pressure. This is either performed by decreasing aqueous fluid inflow or increasing aqueous fluid outflow. Historically, invasive procedures such as trabeculectomy and tube shunt implantation, which created new outflow passages made of either the patient’s natural tissue or via a silicone tube, respectively, were the only surgical options available. Due to higher risks, these procedures were not routinely performed at the time of cataract surgery. If patients had uncontrolled intraocular pressure, these surgeries would be performed during a separate visit to the operating room.
In the last 20 years, several new glaucoma procedures termed Minimally Invasive Glaucoma Surgery (MIGS) have emerged. Each of these MIGS procedures is typically performed in conjunction with cataract surgery. After the cataract is extracted and the intraocular lens is implanted, a gonioscopy lens is used to visualize the trabecular meshwork. These have the advantage of using micro-incisions through the cornea that cause less trauma and scarring to the surrounding conjunctival and scleral tissues. These procedures do not exclude the possibility of traditional surgeries in the future if needed. MIGS include endocyclophotocoagulation (ECP), an endoscopic laser to the ciliary body that decreases aqueous inflow. MIGS also include procedures that increase aqueous fluid outflow, such as trabectome, iStent implantation, Cypass implantation, and Xen 45 gel stent implantation.
iStent implantation involves placing a 1mm titanium stent in the trabecular meshwork, which allows direct flow to Schlemm’s canal. Xen 45 gel stent is a 6mm implant designed to enter the subconjunctival space via the anterior chamber, sparing the conjunctiva for other traditional surgeries. The Cypass implant is a 6mm polyimide stent that allows flow into the supraciliary space, a unique space that has not been accessed successfully in the past. During Trabectome surgery, endocautery is applied to the trabecular meshwork to remove this site of drainage obstruction and allow direct flow into Schlemm’s canal. These new tools to our glaucoma surgery armamentarium have drastically fewer risks than traditional glaucoma surgery.
Employing a MIGS procedure concurrently with cataract surgery may mean decreasing intraocular pressures to goal levels for some patients or it may allow other patients to stop using one or more eye drops. If glaucoma is treated during cataract surgery, it may help avoid the need for a separate glaucoma surgery in the future. With new advents in glaucoma surgery, having cataract surgery can be an excellent opportunity for improved glaucoma control.