MIGS continues to be a surgery option for glaucoma and is a key technology disrupter in ophthalmology.
Reviewed by Michele C. Lim, MD
Minimally invasive glaucoma surgery (MIGs) represents one of the most exciting innovations in ophthalmology, according to Michele C. Lim, MD. Dr. Lim is professor of ophthalmology and vice chair and medical director of the University of California Davis Eye Center, Sacramento, CA. With MIGS becoming more commonplace among glaucoma surgeons, Dr. Lim reviewed the literature to provide a summary of safety and efficacy findings.
MIGS study guidelines
FDA guidelines for study design of MIGS devices recommend that the primary endpoint be the percentage of subjects with at least 20% reduction in mean diurnal IOP from baseline and that the secondary endpoint should be the mean diurnal IOP change from baseline. These guidelines were followed in some of the studies Dr. Lim discussed during the American Glaucoma Society annual meeting earlier this year. MIGS procedures in which an implant is placed in Schlemm’s canal include the iStent Trabecular Micro-Bypass Stent, the newer iStent inject (both from Glaukos), and the Hydrus microstent (Ivantis). The MIGS literature is “robust” regarding both the iStent and iStent inject, a dual-stent system approved by the FDA in 2018, Dr. Lim said.
Focusing on the iStent inject, she discussed two prospective studies in which the system was combined with cataract surgery. In a study by Arriola-Villalobos et al. (n = 20), 86% of patients reached the primary effectiveness endpoint, as did 78% in a study by Hengerer et al. (n = 81).
However, in both studies the mean IOP remained in the mid-teens at follow-up visits 3 to 4 years postoperatively. Dr. Lim also described two studies of the iStent inject implanted as a standalone procedure. Fea et al. reported that 95% of patients (using no medications) reached the primary endpoint versus 92% of patients taking two medications.
In a noncomparative study, Voskanyan et al. found that 72% of patients (using no medications) achieved the primary endpoint. The mean IOP reduction at 12 months was –13 mm Hg for patients in the iStent cohort and –13.2 mm Hg for those using medication in the Fea et al. study and –14.7 mm Hg in the Voskanyan study. The most common adverse events reported in these studies were that the iStent was not visible (1% to 13%), the iStent was obstructed (1% to 3%), or that the IOP was elevated (10%).
Michele C. Lim, MD
E: [email protected]
This article was adapted from Dr. Lim’s presentation at the 2019 meeting of the American Glaucoma Society. Dr. Lim is a speaker for Alcon Laboratories and an investigator for Santen.