EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/407647
EW FEATURE 40 Combined procedures for glaucoma November 2014 by Ellen Stodola EyeWorld Staff Writer AT A GLANCE • The term MIGS was coined in 2009 by Dr. Ahmed. • It was originally known as "minimally invasive" but has since evolved to "microinvasive." • Some procedures are similar to MIGS but do not quite fit the original description. • The iStent is the only MIGS device currently approved in the U.S. Defining MIGS glaucoma surgery," he said. "I felt that it was important to distinguish that class of procedures to better understand what their roles would be in the glaucoma treatment algorithm." A new definition also helps patients to better understand and differentiate one procedure from another. In the past few years, MIGS has evolved, but Dr. Ahmed said that when he initially came up with the concept, there were 5 cardinal features of MIGS. These were an ab interno procedure, biocompatibility with minimal disruption of normal anatomy/physiology, very high safety profile, efficacy of IOP lowering, and quick recovery time. The ab interno procedure uses small incisions without making conjunctival incisions. But invasiveness is not just incision size—it also means to what extent a procedure "invades" or disrupts normal anatomy and physiology of the tissue at hand. "We're altering tissue minimally and keeping the eye relatively untouched," Dr. Ahmed said. MIGS procedures are safer because of their less invasive nature and offer modest efficacy. Finally, the function of the eye returns quickly with these procedures, and MIGS is amenable to do in conjunction with other surgery. Definition "There certainly are a lot of defini- tions, and it's a catchy phrase," Dr. Lewis said. "It's a bit of a marketing phrase describing a new generation of glaucoma surgeries that are microincisional procedures." Dr. Kahook said that MIGS was originally known as minimally invasive glaucoma surgery, and it encompasses "a group of IOP-lower- ing surgeries that avoid disruption of the conjunctiva by leveraging an ab interno approach through a clear cornea incision." He noted that it is usually combined with cataract surgery and can target the aqueous outflow sys- tems or the aqueous inflow pathway with minimal collateral damage. How is having a term like MIGS helpful? "The term MIGS allows physicians to instantly recognize the level of in- tervention that is being discussed," Dr. Kahook said. "While there might be some minor differences in how we perceive MIGS, it is universally understood that this group of in- terventions does not involve a bleb and often denotes procedures that are safer than traditional glaucoma surgeries." Generally, MIGS procedures are used for mild to moderate glaucoma. Every specialty, even outside of ophthalmology, has its own version of MIGS, Dr. Lewis said. This refers to safer, smaller procedures. "MIGS seems like it's been around for a long time, but it's only been 3 or 4 years," he said. "Its usefulness is to explain to non- glaucoma people what the value of these newer procedures are." MIGS-like procedures with different features There are some procedures that are similar to MIGS; however, they may have some different features than what initially qualified under the MIGS definition. "In my book, Trabectome [NeoMedix, Tustin, Calif.] and endoscopic cyclophoto- coagulation (ECP) still fall under the banner of MIGS," Dr. Kahook said. "These procedures fit my definition and are focal treatments that are ab interno and often coupled with cataract surgery." The main difference is that neither of these involves a device staying in the eye, which Dr. Kahook sees as an advantage. "If you can achieve IOP lowering without leaving hardware in the eye, all else being equal, it is preferable," he said. Is there an appropriate term to call those procedures that are close to MIGS? Dr. Kahook sees no reason to have a sub-category of MIGS. "Procedures can either be MIGS or not MIGS," he said. "If, in the future, an entire new group of inter- ventions are identified that justify new nomenclature, then we can address it." Dr. Ahmed said that when he coined the term, there were ini- tially a lot of questions about the definition. Originally, he used the term "minimally invasive" but later switched to "microinvasive." He thought this would better reflect the level that these surgeries were truly working on in the eye versus in general surgery where the term "minimally invasive" is also used. MIGS is often referred to as both "minimally invasive" and "micro- invasive" by different surgeons—but essentially means the same thing. Procedures like canaloplasty are advances in glaucoma surgery, Dr. Ahmed said, but he does not think they qualify as traditional MIGS. He would prefer referencing these procedures as non-penetrating or bleb-less surgeries. Although proce- dures like ECP share MIGS features, they are questionable due to the Coined by Iqbal "Ike" K. Ahmed, MD, the term has become a major part of the glaucoma discussion R ecently, microinvasive glaucoma surgery (MIGS) has become a hot topic not just in glaucoma surgery but across ophthalmology. "The term MIGS has focused the attention of all ophthalmology on glaucoma surgery for the first time," said Reay H. Brown, MD, founding partner of Atlanta Ophthalmology Associates. "It has created a market- ing buzz by giving a catchy name to a movement that has been smolder- ing for some time, but has finally reached a critical mass." Currently, the only approved MIGS device in the U.S. is the iStent (Glaukos, Laguna Hills, Calif.), but there are several more in the pipeline. Ultimately, before these are approved, companies must show both safety and efficacy in results. Iqbal "Ike" K. Ahmed, MD, assistant professor of ophthalmolo- gy, University of Toronto, and head of ophthalmology, Trillium Health Partners, Mississauga, Ontario, Canada; Malik Kahook, MD, Slater Family Endowed Chair in Ophthalmology, and professor of ophthalmology, University of Colorado School of Medicine, Aurora, Colo.; and Richard A. Lewis, MD, Grutzmacher, Lewis & Sierra, Sacramento, Calif., discussed the definition of MIGS and the evolution of the term. Dr. Ahmed coined the term in 2009. "We were coming upon a new generation of procedures that were clearly different than traditional Iqbal "Ike" K. Ahmed, MD "We were coming upon a new generation of procedures that were clearly different than traditional glaucoma surgery. I felt that it was important to distinguish that class of procedures to better understand what their roles would be in the glaucoma treatment algorithm. " –Iqbal "Ike" K. Ahmed, MD